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Application of reverse phase ion-pair partition chromatography to drugs of forensic interest.
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A method is described for determining a wide range of abused drugs by using 1 column, a single isocratic system, and a fixed wavelength (254 nm) ultraviolet detector. Paired-ion chromatography is performed on a reverse phase muBondapak C18 column. Acidic, basic, and neutral drugs, including their corresponding salts, can be determined without prior cleanup. A counter ion, 1-heptane sulfonate, is dissolved in the aqueous organic mobile phase to give a final pH of approximately 3.5. This technique is applicable to ergot alkaloids, phenylethylamines, opium alkaloids, local anesthetics, barbiturates, and other drugs of forensic interest. Five major opium alkaloids in gum opium, namely, morphine, codeine, thebaine, narcotine, and papaverine, can be separated in approximately 20 min.
| 19,415
|
Metabolism of 6-aminonicotinic acid in Escherichia coli.
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A late-log-phase culture of an Escherichia coli nadB pncA double mutant took up 6-[7-14C]aminonicotinic acid and excreted 6-[14C]aminonicotinamide. This mutant also accumulated intracellularly several radioactive compounds which have been tentatively identified as 6-amino analogs of compounds in the pyridine nucleotide cycle. It is concluded that 6-aminonicotinamide and 6-aminonicotinic acid probably exert at least a portion of their bacteriostatic effects by being metabolized, by the enzymes of the pyridine nucleotide cycle, to 6-aminonicotinamide adenine dinucleotide and 6-aminonicotinamide adenine dinucleotide phosphate. These compounds are not electron acceptors and are known inhibitors of some pyridine nucleotide-linked dehydrogenases.
| 19,420
|
Cyclic adenosine 3',5'-monophosphate regulation of membrane energetics in Escherichia coli.
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Mutants of Escherichia coli K-12 lacking functional adenylate cyclase (cya) or the cyclic adenosine 3',5'-monophosphate (cAMP) receptor protein (crp) were compared with their wild type to evaluate the role played by the cAMP-cAMP receptor protein complex in regulating this organism's membrane-associated bioenergetic functions. Both mutants were found to be equally defective in carrying out various electron transport activities. In particular, their capacity for synthesizing a functional oxygen-linked transhydrogenase system was totally repressed, and their content of flavin adenine dinucleotide was reduced by approximately 85%. In addition, it was found that the mutant strains had a decreased ability to generate a protonmotive force and to use this chemiosmotic force to generate adenosine 5'-triphosphate. All these membrane-associated dysfunctions were completely restored to the wild-type state when the cya cells were grown in the presence of exogenous cAMP. As would be expected if these controls were operating at the transcriptional level, the crp cells retained the mutant character even when grown in the presence of this cyclic nucleotide.
| 19,422
|
Alteration of the Bacillus subtilis glutamine synthetase results in overproduction of the enzyme.
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A mutational leading to glutamine auxotrophy was located near a 5-fluorouracil resistance marker in the citB-thyA region of the Bacillus subtilis chromosome. This mutation resulted in a glutamine synthetase with altered kinetic and feedback properties. The specific activity of manganese-stimulated glutamine synthetase activity in crude extracts was 18-fold higher, and the magnesium-stimulated activity was about 30% that of the wild type. Quantitation of the enzyme by precipitation with antibody prepared against pure enzyme confirmed the presence of high enzyme levels in the mutant. This mutation is very closely linked (recombination index of 0.03) to another glutamine auxotroph containing enzyme with altered electrophoretic and heat sensitivity properties. Mutations in the structural gene for glutamine synthetase may result not only in altered catalytic and regulatory properties but also in altered production of the enzyme.
| 19,424
|
Dihydrodipicolinate reductases from Bacillus cereus and Bacillus megaterium.
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Dyhydrodipicolinate reductases were purified 100-fold from crude extracts of B. cereus and B. megaterium and their properties were compared with those of the reductase from B. subtilis. The molecular weights of the reductases of B. cereus and B. megaterium were fount to be 155,000 and 150,000, respectively. These reductases were shown to be free of flavin, unlike the B. subtilis enzyme, which contains flavin. Both NADPH and NADH acted as coenzymes for these two reductases. NADPH being three or four times more effective than NADH. The Km values for NADPH and dihydrodipicolinate were 8 micrometer and 62 micrometer, respectively, with B. cereus reductase, and 13 micrometer and 59 micrometer with B. megaterium reductase. The pH optima of the enzymes from B. cereus and B. megaterium were pH 7.4 and 7.2, respectively. The reductases were inhibited by dipicolinate noncompetitively with respect to dihydrodipicolinate and the Ki values were 85 micrometer and 140 micrometer, respectively. Lysine and diaminopimelate were not inhibitory. The properties of the reductases from B. cereus and B. megaterium were similar, but they differed considerably from those of the B. subtilis enzyme. However, all three Bacillus reductases were markedly inhibited by dipicolinate, unlike the enzyme from E. coli.
| 19,431
|
Accumulation of phosphoenolpyruvate in red cells incubated with the phosphate ester in an acidified isotonic sucrose medium.
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Accumulation of exogenous phosphoenolpyruvate against the concentration gradient was observed when human red cells were incubated in an acidified isotonic sucrose medium. Fluoride increased the apparent accumulation by inhibition of the intracellular metabolic interconversion of the phosphate compound. The accumulation appeared to be specific for phosphoenolpyruvate and the accumulation rate for 3-phosphoglycerate, which has a molecular size and pKa similar to those of phosphoenolpyruvate, was less than one-tenth of the rate of phosphoenolpyruvate. Red cells incubated in the acidified sucrose medium tended to adhere to each other when examined with a scanning electron microscope.
| 19,438
|
A sensitive substrate for the clotting enzyme in horseshoe crab hemocytes.
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An endotoxin-activated hemocyte lysate from horseshoe crab (Tachypleus and Limulus) was found to hydrolyze specifically BZ-Ile-Glu-Gly-Arg-p-nitroanilide, which was recently introduced as the substrate for assay of the blood coagulation factor, Factor Xa. Further, this amidase activity increased by increasing the concentration of bacterial endotoxin (Salmonella minnesota R595) added to the lysate. Thus, the measurement of the amidase activity in the hemocyte lysate can be very useful to detect and determine the endotoxin.
| 19,439
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A correlation between the secondary structure of DNA and the reactivity of adenine residues with chloroacetaldehyde.
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The rate of reaction of chloroacetaldehyde (0.039 M) with the "free" adenine residue in deoxyadenosine-5'-phosphate (dAMP) at pH 6.5 has been found to be nearly equal to that at pH 4.5. Practically 100% of the adenine is converted to a fluorescent product (epsilon-adenine residue) on incubation for 60 h at 37 degrees C and pH 6.5. Of the adenine residues in "single-stranded" DNA, however, only 14% react with chloroacetaldehyde (0.039 M) under the same incubation conditions. The reaction rate of this 14% is nearly equal to that of dAMP, but the fluorescence of the product is appreciably quenched; the quantum yield is only 0.45 times that of the "free" adenine residue. In "double-helical" DNA, on the other hand, no adenine residue has been found to react with chloracetaldehyde. Possible application of these findings to structural studies of DNA is suggested.
| 19,443
|
Interaction of thiolsubtilisin with Streptomyces subtilisin inhibitor, SSI.
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Subtilisin BPN' was chemically converted to thiolsubtilisin and the interaction of this modified enzyme with Streptomyces subtilisin inhibitor (SSI) was examined. SSI competitively inhibited the esterolytic activity of thiolsubtilisin toward p-nitrophenyl acetate with a K1 value of 1.3 X 10(-5) M at pH 7.5 Spectrophotometric analysis of the interaction between SSI and the modified enzyme yielded a Kd value of 4 X 10(-5) M at pH 9.7. These values are about 10(5)-fold greater than the Kd value (less than 10(-9) M at pH 7.5) for the native enzyme. This indicates that the small change in the active site structure of subtilisin (Ser221 to Cys221) leads to a considerable decrease in the binding affinity (by about 6-7 kcal/mol) to SSI.
| 19,450
|
Properties of soluble rat brain histone lysine methyltransferase.
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Histone-lysine methyltransferase has been solubilized from rat brain chromatin by repeated extraction with distilled water. The enzyme was further purified by chromatography on DEAE-cellulose and gel filtration. With chromosomal-bound histones as substrates, the enzyme methylated only the lysyl residues in histones H3 and H4. The ratio of N epsilon-mono-: N epsilon-di-: N epsilon-trimethyllysine in histone H3 was 1.8:1.0:0.45 and the ratio of N epsilon-mono-: N epsilon-dimethyllysine in histone H4 was 0.7:1.0. The enzyme loses specificity with soluble histones as substrates; however, histones H3 and H4 were still the best methyl acceptors. The pH optima for the enzyme with soluble histones H3 and H4 as substrates were 8.2 to 8.7 and 7.2 to 8.0, respectively. S-Adenosyl-L-homocysteine, one of the products of the reaction, was a competitive inhibitor with respect to S-adenosyl-L-methionine.
| 19,459
|
Purification from hamster cells of the multifunctional protein that initiates de novo synthesis of pyrimidine nucleotides.
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Carbamyl-P synthetase (EC 2.7.2.9), aspartate transcarbamylase (EC 2.1.3.2), and dihydro-orotase (EC 3.5.2.3), the first three enzymes of the de novo pathway for synthesis of pyrimidine nucleotides, have been co-purified as a single oligomeric protein from a mutant line of hamster cells selected for its ability to resist N-(phosphonacetyl)-L-aspartate (PALA), a potent and specific inhibitor of aspartate transcarbamylase. All three enzymes overaccum,late in the mutant cells (Kempe, T.D., Swyryd, E.A., Bruist, M., and Stark, G.R. (1976) Cell 9, 541-550) and the oligomer represents nearly 10% of the total cellular protein. Tens of milligrams of oligomer have been purified to homogeneity by a simple and rapid procedure, with recovery of about 50% of all three activities. The pure protein contains only one size of polypeptide, Mr approximately 200,000, as revealed by electrophoresis in danaturing gels. All three enzyme activities are associated with this polypeptide, indicating that it is multifunctional. Further evidence for a multifunctional protein is provided by titration of the oligomer with radioactive PALA, which reveals that the number of PALA binding sites approximately equals the number of polypeptide chains. The isolated multifunctional protein is a mixture of trimers and hexamers.
| 19,472
|
Effects of sugars on melanogenesis in cultured melanoma cells.
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A permanent cell line C2M of mouse melanoma B16 was highly melanized in a modified Eagle's MEM supplemented with 10% calf serum, when the medium contained 1 mM galactose and 10 mM pyruvate instead of 5.5 mM glucose. The activity of the key anzyme for melanogenesis, tyrosinase (EC 1.14.18.1), of living cells cultured in the galactose-pyruvate medium was consistently 27 times higher than that of cells in normal MEM. This high level of tyrosinase activity was maintained in the stationary phase, in contrast to the activity of cells in normal medium, which decreased sharply in the stationary phase. It seems likely that tyrosinase activity is suppressed by the presence of glucose rather than stimulated by galactose. This modified medium should be useful obtaining a high level of tyrosinase activity in living cells in culture and in cell-free extracts.
| 19,484
|
Comparison of bumetanide and hydrochlorothiazide on renal potassium and hydrogen ion excretion.
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The purpose of this study was to compare the renal electrolyte excretion pattern of bumetanide with that of hydrochlorothiazide in dogs anesthetized with pentobarbital. In bumetanide-treated animals, mean sodium excretion rose to 12 per cent of the filtered load, while hydrochlorothiazide increased sodium excretion to 4 per cent of the filtered load. After bumetanide, urine pH fell from 6.1 to 5.1 and net hydrogenion excretion increased significantly. After hydrochlorothiazide, urinary pH went from 6.4 to 7.4, and there was no change in net hydrogen ion excretion. Potassium excretion rose to 106+/-22 muEq/min with bumetanide and to 99+/-17 muEq/min with hydrochlorothiazide. These changes in electrolyte excretion occurred despite lack of changes in arterial blood gases, arterial blood pressure, and glomerular filtration rate. In addition, bumetanide did not exert an inhibitory effect on potassium excretion under conditions of potassium loading. It is concluded that bumetanide produces a higher urinary Na+:K+ ratio with a lower pH than hydrochlorothiazide and that renal potassium ion excretion in response to sulfamoyl diuretics is not solely dependent on the rate of sodium excretion.
| 19,505
|
Immune responses during measles infection in immunosuppressed Rhesus monkeys.
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Rhesus monkeys immunosuppressed with horse anti-human thymocyte gamma-globulin (ATG) were infected with measles and simultaneously inoculated with sheep erythrocytes (SRBC), a thymus-dependent antigen, and with pneumococcal polysaccaride type III (SSS-III), a thymus-independent antigen. ATG treatment alone suppressed SRBC antibody production, had no effect on SSS-III antibody production, and effectively eliminated circulating T cells compared to nonsuppressed monkeys. ATG treatment of measles-infected monkeys resulted in delayed virus clearance and delayed antibody production compared to nonsuppressed infected monkeys. After cessation of ATG treatment, measles antibodies and T cells reached normal levels, and measles virus was eliminated. Thus, immune clearance of measles virus is T cell-dependent, but the relative roles of cellular- and humoral-mediated immunity in vivo could not be clearly separated. Also, measles infection was associated with a decreased T cell mitogen responsiveness of circulating lymphocytes but not of lymph node lymphocytes, suggesting an altered circulating pattern of the cells responsible for delayed hypersensitivity. Also, measles infection had no effect on T-dependent antibody production to SRBC.
| 19,536
|
Relations between ameboid movement and membrane-controlled electrical currents.
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We have studied the pattern of electrical currents through amebas (mainly Chaos chaos) with an ultrasensitive extracellular vibrating probe. Amebas drive both steady currents and current pulses through themselves. Relatively steady current with an average surface density of 0.1-0.2 muA/cm2 enters the rear quarter of an ameba and leaves its pseudopods. Streaming reversals are preceded by changes in this current pattern and the region with the largest new inward current becomes the new tail. Ion substitution studies suggest that some of the steady inward current is carried by calcium ions. Characteristic stimulated pulses of current sometimes follow the close approach of the vibrating probe to the side of an advancing pseudopod. Such a pulse enters the cytoplasm through a small patch of membrane near the probe (and seems to leave through the adjacent membrane), is usually followed by hyaline cap and then by pseudopod initiation, is calcium dependent, lasts about 5-10 s, and has a peak density of about 0.4 muA/cm2. Spontaneous pulses of similar shape and duration may enter or leave any part of an animal. They are much less localized, tend to have higher peak densities, and occur in physiological salt solutions at about 0.2-4 times per minute. Retraction of a pseudopod is always accompanied or preceded by a spontaneous pulse which leaves its sides.
| 19,555
|
Temperature-dependent changes of chloride transport kinetics in human red cells.
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Chloride self-exchange in human red cells was studied between 0 degrees C and 38 degrees C. At higher temperatures the flow-tube method was used. Although the general features of chloride transport at 0 degrees C and 38 degrees C are similar, the following differences were found: (a) the maximum pH of chloride self-exchange flux was lowered 0.6 pH unit from 7.8 to 7.2 when temperature was increased from 0 degrees C to 38 degrees C; (b)the apparent half-saturation constant increased from 28 mM at 0 degrees C to 65 mM at 38 degrees C; (c) chloride transport at body temperature is slower than predicted by other investigators by extrapolation from low-temperature results. Chloride transport increased only 200 times when temperature was raised from 0 degrees C to 38 degrees C, because the apparent activation energy decreased from 30 kcal mol(-1) to 20 kcal mol(-1) above a temperature of 15 degrees C; (d) a study of temperature dependence of the slower bromide self-exchange showed that a similar change of activation energy occurred around 25 degrees C. Both in the case of Cl(-) (15 degrees C) and in the case of Br(-) (25 degrees C), critical temperature was reached when the anion self-exchange had a turnover number of about 4x10(9) ions cell (-1)s(-1); (e) inhibition of chloride transport by DIDS (4,4'- diisothiocyano-stilbene-2,2'-disulfonate)revealed that the deflection persisted at 15 degrees C at partial inhibition (66 percent) presumably because DIDS inactivated 66 percent of the transport sites. It is suggested that a less temperature- dependent step of anion exchange becomes rate limiting at the temperature where a critical turnover number is reached.
| 19,556
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The effect of temperature on the tensile strength and disintegration of paracetamol and oxytetracycline tablets.
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The tensile strengths and disintegration times of paracetamol and oxytetracycline tablets at room temperature are higher when they have been prepared at high temperatures, e.g. 85 degrees, than at room temperature or below, e.g.--20 degrees. The activation energies of the two materials, 3 and 1 k cal mol-1 (13 and 4kJmol-1) respectively, were derived from plots of log tensile strength and log disintegration time versus the reciprocal of the absolute temperature. The results have been explained in terms of sintering theory and the formation of welded bonds between particles.
| 19,574
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Fluorometric determination of nadolol in human serum and urine.
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To determine nadolol, a new beta-adrenergic blocking agent, in serum and urine, the drug is extracted into n-butyl acetate or ether from alkaline potassium chloride saturated samples. After back-extraction into 0.1 N HCl, the drug is oxidized with periodic acid; the resulting aldehyde is coupled with o-phenylenediamine to produce a fluorescent compound. The method can measure as little as 0.01 microgram of nadolol/sample.
| 19,616
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An in vivo assay for the analysis of the biological potency and structure-activity relationships of narcotics: serum testosterone depletion in the male rat.
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An in vivo method for the assessment of the agonistic-antagonistic activities and structure-activity relationships of the narcotics is described. The method, which is based on the depletion of serum testosterone levels by the narcotics in the male, satisfies all of the criteria necessary for a valid narcotic assay: 1) The ability of the narcotics to deplete serum testosterone levels is stereospecific; 2) naloxone competitively inhibits their effects; 3) and the relative potencies of the drugs in depressing serum testosterone levels parallels their activity in inhibiting electrically induced contractions of the guinea-pig ileum, the binding of [3H]opiates to "receptors" in rat brain homogenates and their relative effectiveness as analgesics. Although only rats were used in the current studies, the method can be easily adapted for use in any species, including man.
| 19,620
|
[Constitutive synthesis of cellulase by Trichoderma lignorum].
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The induction of cellulase synthesis by lactose was studied in the resting cells of Trichoderma lignorum OM 534. The effect depended on the concentration of lactose, pH, and the age of the mycelium. The induction of the enzyme synthesis by lactose is supressed by glucose and its metabolites. The repression by glucose is partly eliminated by Cyk 3'-5'-AMP, theophylline, and coffeine. The induction of cellulase by lactose is regarded as a derepression of the synthesis of this enzyme as a result of slow assimilation of the disaccharide. The synthesis of cellulase in T. lignorum is presumed to be constitutive.
| 19,684
|
The role of mineral surfaces in the origin of life.
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Adsorption of nucleoside phosphates on the surfaces of volcanic rocks has been studied. Differences in the absorption of some nucleoside phosphates on the surface of basalt cinder have been found. Differences in the adsorption of similar molecules on different mineral surfaces have also been shown. Different adsorptive capacities may have served as a mechanism for the selection of organic molecules during prebiotic evolution.
| 19,721
|
An automatically balancing isolation amplifier for the decoupling of measuring systems with high impedances.
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It is theoretically shown that different conditions of coupling and grounding cause error voltages with the simultaneous use of two high-impedance measuring systems (e.g. pH electrodes). By the use of special amplifiers using optical transmission systems these error voltages are prevented. The transmission characteristics of the couplers are sensitive to changes in temperature due to the incorporation of infrared emitters in the system. An amplifying equipment with high d. c. stability was developed. The temperature drift was suppressed by the use of a special chopper stabilisation.
| 19,727
|
Rates of formation and thermal stabilities of RNA:DNA and DNA:DNA duplexes at high concentrations of formamide.
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The thermal stabilities of RNA:DNA hybrids are substantially greater than those of DNA:DNA duplexes in aqueous electrolyte solutions containing high concentrations of formamide. Association rates to form DNA:DNA duplexes and DNA:RNA hybrids have been measured in these solvents. There is a temperature range in which DNA:DNA rates are negligible and RNA:DNA rates close to optimal.
| 19,730
|
The properties of native and denatured DNA in buoyant rubidium trichloroacetate at neutral pH.
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Aqueous RbTCA is generally suitable as a buoyant solvent for both native and denatured DNA at neutral pH and room temperature. Native PM-2 DNA II, for example, is buoyant at 3.29 M salt, 25 degrees C; whereas the denatured strands band together at 4.52 M. Two properties of the solvent make this system uniquely useful for separations based upon the extent of secondary structure. First, the melting transition temperature for chemically unaltered DNA is depressed to room temperature or below. Second, the buoyant density increase accompanying denaturation is extraordinarily large, 174 mg/ml for PM-2 DNA II. This value is three times that found in aqueous NaI and ten times that for CsCl. The properties of the RbTCA buoyant solvent presented here include the compositional and buoyant density gradients and the buoyant density dependence upon base composition. The DNA remains chemically unaltered after exposure to RbTCA as shown by the absence of strand scissions for closed circular DNA and by the unimpaired biological activity in transformation assays. Intact virion DNA may be isolated by direct banding of whole virions in RbTCA gradients without prior phenol extraction. Strongly complexed or covalently bound proteins may be detected by their association with the buoyant polymer in the denaturing density gradient.
| 19,731
|
Electrophysiological experiments on the mechanism and accuracy of neuromuscular specificity in the axolotl.
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The supracoracoideus muscle of the axolotl shoulder girdle is innervated by two nerves, the supracoracoideus nerve (SC) supplying most of the muscle and the posterior supracoracoideus (PSC) supplying the posterior corner. All the muscle fibres are multiply innervated and at the border between the two innervations many muscle fibres, when penetrated by a microelectrode, show junction potentials from both nerves. In such cases one junction potential is often very small, below the threshold for exciting muscle contraction, the other large and effective at exciting the muscle. If the SC nerve is cut, the territory of the PSC nerve expands over several weeks. Upon regrowth of the cut nerve it reinnervates its old muscle fibres and removes the previous foreign innervation, the borderline between the two nerve territories being established exactly as before. This depends upon two processes, sprouting of nerves and a competitive repression of transmission from nerves ending on foreign muscle fibres.
| 19,787
|
Negative naloxone effects in schizophrenic patients.
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On the basis of the hypothesis that the opiate-like neuropeptides, such as beta-endorphin, may be involved in the etiology of schizophrenic symptoms, naloxone 1,2 mg and placebo were administered intravenously to 8 schizophrenic patients, using a double-blind, crossover design. Naloxone was not found to be different from placebo in effecting schizophrenic symptoms, including hallucinations and delusions.
| 19,807
|
[Effect of methionine sulfone on the growth of Citrobacter intermedius C3 (author's transl)].
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Specific activity of glutamate dehydrogenase (GD) and glutamate synthase (GtS) has been determined in the wild strain C3 and on a non excreting pro- mutant strain. Methionine sulfone shows inhibitory effects on their growth. The addition of alpha-ketoglutarate to the medium prevents the inhibitory effect and increases the GtS specific activity in both strains. The physiological effect of methionine sulfone and its suppression by alpha-ketoglutarate is discussed.
| 19,817
|
Red cell lysis coupled to the peroxidation of liver microsomal lipids. Compartmentalization of the hemolytic system.
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As a contribution to the understanding of the mechanisms by which addition of erythrocytes to liver microsomes incubated in the NADPH dependent system results in hemolysis, experiments are presented here in which the system containing actively peroxidizing microsomes was separated from the system containing the red blood cells by a dialysis membrane. It is shown that when liver microsomes were incubated with NADPH, lipid peroxidation, as measured by the formation of malonic dialdehyde (MDA), rapidly took place. The MDA concentration tended to equilibrate across the dialysis membrane. After a lag phase of 60 min, lysis of erythrocytes contained in the dialysis tube, started. It reached its maximal level (more than 80%) at 110 min of incubation. These results strongly suggest the possibility that toxic products originating during the course of lipid peroxidation induce pathological effect at distant loci. Furthermore, the accomplishment of a compartmentalization of the two systems involved in the reaction, may offer an approach to the recognition of the toxic factors.
| 19,823
|
[Thermal inactivation and storage behavior of technologically important enzymes. IV. Spinach lipid-acyl-hydrolase].
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The thermal reaction of a lipid-acyl-hydrolase which seems to be important for the quality preservation of vegetable foods, was investigated in spinach. The authors applied a simple in-situ method using thin-layer chromatography which had been developed for the enzyme determination, to follow the thermal inactivation of the lipid-acyl-hydrolase by measuring the decomposition of lecithin, mono- und digalactosyl diglycerides. According to the inactivation curves, the enzyme is relatively little resistant to heat. Since the D- and z-values resulting from the inactivation curves for phospholipase, mono- and digalacto-lipase activities are almost the same, it can be assumed that the lipid-acyl-hydrolase is a multi-function enzyme in spinach.
| 19,886
|
[Thermal inactivation and storage behavior of technologically important enzymes. I. Horseradish and spinach peroxidase].
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The thermal inactivation and storage behaviour for horseradish and spinach peroxidases were investigated in defined systems, in spinach also within its natural environment. The inactivation curves of either enzyme show a sharp bend which is clearly visible at low, but not at higher temperatures. The D-values were taken from the inactivation curves. z-values resulting from the D-values were 25.5 degrees C for horseradish peroxidase, 13 degrees C for isolated peroxidase and 18 degrees C for peroxidase in spinach extract. Horseradish peroxidase was relatively heat-resistent at pH 6.0, spinach peroxidase at pH 5.0-6.0; both enzymes were found to be highly susceptible to heat at pH 4.0. Peroxidase isolated from spinach responded differently to heating than the enzyme in spinach extract or suspension. This discrepancy indicates that certain model experiments cannot be transferred to foods. Heated peroxidase from horseradish and spinach were found to regenerate during storage; the extent of regeneration depended on the pH.
| 19,887
|
[Several indices of the methylation process in schizophrenic patients].
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The paper deals with a study of 83 patients with different forms of schizophrenia and 15 normals where the methylating activity in converting nicotinamid into methylnicotinamid was determined and the activity of catechol-methyltransferase. In schizophrenic patients there is an increase of the methylating activity which significantly correlated with hallucinatory symptoms in the clinical picture. In patients with cataono-paranoid, paranoid syndromes and simple forms of schizophrenia the methylating activity is seen significantly less frequently. The disappearance of alleviation of hallucinations, due to neuroleptical drugs is accompanied by normalization of the methylating activity. Any significant differences in the excretion of isdarin as an index of cathechol-o-methyltransferase activity in normals and schizophrenic patients was not established.
| 19,907
|
Peripheral haemodynamics in essential hypertension.
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Previous studies have indicated the existance of haemodynamically important structural vascular changes in patients and animals with hypertension. Possible pathophysiological implications of these changes are discussed. Two studies dealing with the question of reversibility of the structural changes on long-term blood pressure lowering therapy are described. The results indicate that the changes are partially but not completely reversible.
| 19,929
|
Prolactin release inhibiting and stimulating factors in the hypothalamus.
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Catecholamines, especially norepinephrine and dopamine, as well as GABA extracted from porcine hypothalamic tissue, were found to possess PIF activity in vitro. However, more work is needed to determine whether or not the effects of GABA or catecholamines on prolactin release are physiological or pharmacological. Until such studies are completed and until the chemical nature and biological roles of other substances with PIF activity found in the hypothalamus are clarified, no conclusion as to the nature of the physiological inhibitor of prolactin release should be made.
| 19,952
|
[Action of dibencozide on nitrogen metabolism in immediate and long-term postoperative resuscitation].
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The catabolic orientation of the immediate post-aggression phase is aggravated in neurosurgery by the almost routine prescription of corticosteroids. This emphasises the value of any treatment which might limit this orientation. The authors report their experience with the use of dibencozide, with its known facilitating action upon nitrogen assimilation, in the absence of any side effects.
| 20,005
|
Extrinsic neural influences on gastrointestinal motility.
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The gastrointestinal tract is capable of carrying on all its major functions after all extrinsic nerves have been cut. This automaticity is due to the local nervous mechanisms in the walls of the gastrointestinal tract and the inherent properties of the smooth muscles in its walls, and gastrointestinal hormones. All levels of the central nervous system have been shown, by stimulation and ablation studies, to influence the motility of the entire gastrointestinal tract. Throughout many cerebral areas there are loci which, on stimulation, exert both inhibitory, and less often, excitatory influence on gastrointestinal motility. These influences are mediated by sympathetic and parasympathetic visceral efferent nerves, as well as humoral agents from the neurohypophysis. Thus, they impose an influence of higher control on the automatically efficient intrinsic motility. They are guided by information received from visceral, cranial, and somatic afferents, as well as intracerebral, or psychic inputs. Under normal circumstances they only influence gastrointestinal activity as will best afford the optimal functioning of a performance done automatically with efficiency and finesse.
| 20,014
|
Transovarial transmission of Rickettsia-like microorganisms in mosquitoes.
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The wolbachiae found in Culex pipiens and the Tafahi strain of the A. scutellaris group are small rickettsia-like symbionts of the gonads. They are extrachromosomal self-replicating units that are vertically transmitted through the ovaries. Their presence in the only two groups of mosquitoes known to exhibit incompatibility, the fact that they are found in only the Tafahi strain, and the loss of incompatibility after removal of Wolbachia in C. pipiens are compelling evidence for the role that Wolbachia plays in incompatibility.
| 20,018
|
Generalized glycogenosis in beef shorthorn cattle--heterozygote detection.
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A preliminary study of acidic alpha-glucosidase in a variety of tissues was carried out in an attempt to develop a test which might be used to detect individuals heterozygous for the genetype associated with generalized glycogenosis in beef Shorthorn cattle. Of the tissues readily available peripheral lymphocytes were chosen as being likely to be the most suitable. It was concluded that, when coupled with genealogical information, assays of alpha-glucosidase in extracts of lymphocytes were useful for identifying heterozygous individuals with a reasonably high degree of probability.
| 20,072
|
The effect of mental arithmetic in normotensive and hypertensive subjects, and its modification by beta-adrenergic receptor blockade.
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1 The effects of a 5-min period of sustained mental arithmetic upon blood pressure and heart rate were determined in several groups of healthy subjects and hypertensive patients. 2 The arithmetic produced significant increases in heart rate and blood pressure (both systolic and diastolic) in both normotensive and hypertensive subjects. 3 The blood pressure changes were neither attenuated nor enhanced by the prior administration of basis. 4 In subjects habituated to the test the heart rate increase was unaffected by the drugs, but in those less familiar with the test it was usually attenuated. 5 Although the beta1-adrenoceptor selective blocker, metoprolol, caused decreases in baseline values for blood pressure and heart rate similar to those observed with the use of the two non-selective blockrs, it was shown in a double-blind crossover comparison with propranolol that the haemodynamic changes provoked by the mental arithmetic were not less in the presence of beta1-receptor blockade than when both beta1- and beta2-receptors were blocked. 6 These findings suggest that, during beta2-adrenoceptor blockade, the haemodynamic effects of minor mental stress are not exaggerated because of uncompensated alpha-receptor mediated vasoconstriction, such as occurs following adrenaline infusion.
| 20,124
|
Magnetic resonance investigation of ionizable residues at the active site of thermolysin.
|
The details of the pH dependence of the thermodynamic and magnetic interactions of the active-site region of thermolysin in which manganese has replaced the active-site zinc atom and the inhibitor N-trifluoroacetyl-D-phenylalanine have been examined. These show a number of ionizable groups in the active-site region. A cooperative displacement of manganese at the catalytic site is observed as pH is lowered. This appears to be the result of the protonation of histidine-142 and -146 which act as metal ligands. The metal is 50% displaced at pH 6.0. At higher pH values, the environment of the bound manganese changes as a result of the ionization of at least two groups of approximate pKa = 8.5 and 9.5. These values are assigned to tyrosine-157 and to the water molecule which acts as a metal ligand at the active site. The binding behavior of the inhibitor strongly suggests that two molecules of inhibitor bind to the enzyme. The weaker site is competitive with the synthetic substrate FAGLA (furylacryloylglycyl-leucinamide), while the strong site has no effect on FAGLA hydrolysis. This second site is in the vicinity of the active site with a distance of 8 A or less between the trifluoromethyl group and manganese bound at the active site.
| 20,127
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Dissociation of growth hormone and prolactin response to levodopa during pyridoxine administration.
|
500 mg of levodopa was administered orally to 8 normal subjects and induced an increase of growth hormone (GH) and a decrease of prolactin (PRL) secretion. The levodopa-induced GH release was inhibited by an intravenous infusion of pyridoxine; on the contrary, the PRL response to levodopa was enhanced by pyridoxine infusion. This dissociation of GH and PRL responses to levodopa during pyridoxine infusion appears to be mediated by peripheral acceleration of the conversion of levodopa to dopamine. Since dopamine does not penetrate the blood-brain barrier, the enhanced PRL decrease observed during pyridoxine infusion might be explained only on the basis of a mechanism of action exerted by dopamine on extra blood-brain barrier sites.
| 20,170
|
The uptake and overflow of radiolabelled beta-adrenoceptor blocking agents by the isolated vas deferens of the rat.
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1. A comparison of uptake into and overflow from the isolated vas deferens of the rat has been made between [3H]-noradrenaline ([3H]-NA), [14C]-D-sorbitol and three radio-labelled beta-adrenoceptor blocking agents, [14C]-practolol, [14C]-(+/-)-propranolol and [3H]-penbutolol. 2. The accumulation of [3H]-NA after 30 min incubation was reduced by desmethylimipramine (DMI) 1 X 10(-8)M and was also reduced in vasa from rats pretreated with 6-hydroxydopamine (6-OHDA). This was not so with [14C]-D-sorbitol. 3. 6-OHDA pretreatment of the rats reduced the uptake of [3H]-penbutolol after 30 min incubation but not that of [4C]-propranolol or [14C]-practolol. DMI 1 X 10(-8)M did not alter the tissue uptake of [14C]-propranolol, [14C]-practolol or [3H]-penbutolol. 4. Electrical stimulation of vasa preloaded with [3H]-NA caused a significantly greater increase in [3H]-NA overflow than during the resting, unstimulated periods. No such increase in overflow was observed with [14C]-sorbitol or any of the three beta-adrenoceptor blocking agents use. 5. The beta-adrenoceptor blocking agent penbutolol was shown to possess adrenergic neurone blocking activity in the isolated vas deferens of the rat. 6. It is concluded that any effect that practolol or (+/-)-propranolol have on noradrenergic neurones is brought about without the need for these drugs to gain access to the interior of the neurone.
| 20,192
|
Proximal-distal absorptive gradients in the in vivo intestine of normal and infected (Hymenolepis diminuta: Cestoda) rats.
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Using a single-pass perfusion technique, H2O, Na+, Cl-, HCO3-, and glucose absorption were studied in the jejunum and proximal and distal ileum of rats either uninfected or infected with a tapeworm parasite (Hymenolepis diminuta). The effect of parasitization, region of the intestine, type of buffer, and concentration of glucose in the perfusion fluids on the transport data were analyzed by univariate and multivariate techniques. Proximal-distal flux gradients were observed for water and all the solute species studied, as well as for glucose- and bicarbonate-stimulated salt and water transport; there was a decreasing sensitivity to low pH proceeding distally. The major regional differences occurred between the proximal and distal ileum, with the fluxes in the jejunum being similar to those in the proximal ileum. Na+, H2O, and glucose transport decreased, while Cl- absorption increased, proceeding distally. The parasites diminished the rates of absorption of glucose, salt, and water, and altered the flux gradients, particularly the Na+ and HCO3- transport gradients. The differences in the gradients between control and infected animals were related to differential sensitivity of the different transport systems in the various regions of the gut to parasitism.
| 20,212
|
Adult height of patients treated in childhood for undescended testes.
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101 patients successfully treated for undescended testes with human chorionic gonadotrophin (HCG) or with HCG followed by surgery reached normal adult heights. Deviations from normal growth in individual patients did not appear to be related either to their earlier undescended testes or to the successful therapy, but rather to their genetic background. Therefore, apart from patients with chromosomal abnormalities and other primary causes for maldescent of the testes, boys with undescended testes show a normal distribution for height and do not represent a different population with regard to growth.
| 20,309
|
Adult metachromatic leukodystrophy. I. Clinical manifestation in a female aged 44 years, previously diagnosed in the preclinical state.
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In a 5-year follow-up of a case of adult metachromatic leukodystrophy, already diagnosed in the preclinical stage, the development of the symptoms of this disease could be studied in detail: initially, lack of drive, emotional lability and depressive mood. At the same time, pain in the arms and beginning gait disturbance. Later, impairment of memory and concentration, disorientation, inadequate behavior and progression of gait disturbance. Finally spastic atactic gait with small steps and dyspractic components, coordination disturbances with writing dysfunction, fast dysarthric speech, hyperkinetic activity, compulsory emotional outbursts and progressive dementia. Only minor neurological signs such as reflex abnormalities. In the EEG, slight slowing of frequencies compared to earlier tracings. Increasing diminution of nerve conduction velocity in the lower limbs. Only minor increase of CSF protein (51 mg%). In spite of normal vision, evoked visual potentials abnormal, response of optical and electrical blink reflexes delayed. Imperfect filling of gallbladder. No significant quantitative changes of the biochemical parameters compared with the findings made 5 years earlier (excretion of urinary sulfatides, diminished activity of arylfulfatase A in urine and leukocytes).
| 20,310
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The problem of sea urchin egg fertilization and its implications for biological studies.
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The analysis of sea urchin egg fertilization shows that several phenomena common to other biological systems are involved: cell recognition, cell fusion, exocytosis and initiation of mitotic activity. Both the role of calcium ions in cell fusion and exocytosis and the function of the cell surface in the initiation of mitotic activity appear to have general applicability. The study of fertilization can contribute to the elucidation of these processes and, reciprocally, progress in this field can help to advance our understanding of the mechanisms of fertilization in sea urchins and other organisms.
| 20,321
|
The clinical efficacy of the repeated transcervical instillation of quinacrine for female sterilization.
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The safety and efficacy of the repeated transcervical instillation of quinacrine hydrochloride in a suspension of 5 ml of 2% Xylocaine was evaluated in 200 patients. All instillation procedures were performed during the proliferative phase of the menstrual cycle: the second instillation was made in the first menstrual cycle following the initial instillation and the third and last instillation at 6 months after the first. None of the patients used any adjunctive contraceptives. Follow-up visits were scheduled at 6-month intervals after the last instillation. The potentially serious complications following the instillation were four cases of cortical exitation, and one case of acute adnexitis. The second instillation was not performed for 16.0% and the third instillation was not performed for 16.7% of the patients, for medical and/or personal reasons. Fifty-one pregnancies were reported, 41 (80.4%) before completion of the three instillations. The results of this study show that the instillation schedule used is unsatisfactory for widespread use. Additional studies are currently being conducted to evaluate the use of an adjunctive contraceptive up to the time of the third instillation in order to reduce the high pregnancy rate.
| 20,347
|
Interrelationships between histamine, prostaglandins, and cyclic AMP in gastric secretion: a hypothesis.
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Based on the current experimental evidence, a model is proposed for mutual interactions of histamine, prostaglandins, and cyclic AMP in regulation of gastric secretion and pathogenesis of peptic ulcer. Histamine acting on H2-receptor-associated adenylate cyclase stimulates cyclic AMP formation and consequently secretion of hydrochloric acid in oxyntic cells. Prostaglandins (mainly E type) in another cell population stimulate cyclic AMP formation which may lead to formation of glycosaminoglycans and glycoproteins. Glycosaminoglycans and glycoproteins may have antisecretory and cytoprotective properties. In addition to this effect, prostaglandin endoperoxides may inhibit histamine-stimulated cyclic AMP formation in oxyntic cells.
| 20,385
|
Gastric adenosine triphosphatases: a review of their possible role in HCl secretion.
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In the search for gastric ATPases that might be related to the mechanism of HCl secretion, an interesting and rather unique K+-stimulated ATPase has been discovered. This enzyme is isolated from oxyntic cells and has been associated with the apical plasma membrane and/or tubulovesicular system. Membrane vesicles containing the K+-stimulated ATPase transport H+ into the vesicular lumen under the appropriate conditions of ATP, Mg2+, and KCl. This process can be measured by pH electrode, binding of certain metachromatic dyes to "energized" sites, or accumulation ratios of substances with appropriate pK values. Vesicular interior can be acidified to pH 3.5 or below. At the present time, it is difficult to distinguish between an electrogenic H+ pump and an electroneutral H+/K+ exchange mechanism. A hypothetical scheme for the gastric H+ secretory mechanism is proposed which fits much of the data from studies on the K+-ATPase, vesicular transport, and intact gastric mucosa.
| 20,386
|
[Drug effects on blood pressure and heart rate in unanesthetized animals. (1). Effects of beta-blocking agents (author's transl)].
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beta-Blocking actions of orally administered Kö 1400 and tiprenolol, new beta-blocking agents, were studied in unanesthetized rats and dogs, using a fall of blood pressure and an increase in heart rate produced by isoproterenol as a measure of beta-receptor activation. Blood pressure was recorded from the aorta of the dog and the caudal artery of rat via indwelling catheter, and heart rate of the dog was recorded by a cardiotachometer triggered by R waves of the lead II electrocardiogram. Mean resting blood pressure was 116 mmHg in rats and 93 mmHg in dogs, and heart rate was 99 beats/min in dogs. Isoproterenol (0.5 microgram/kg) was injected via indwelling venous catheter. Kö 1400, tiprenolol and propranolol inhibited the hypotension and tachycardia induced by isoproterenol at an oral dose level of 2 mg/kg or more. beta-blocking action in these preparations was found to be tiprenolol greater than Kö 1400 greater than propranolol. Pharmacological half life of tiprenolol was longer than that of propranolol, whereas that of Kö 1400 was shorter. No selectivity of beta-blocking actions was observed with all three beta-blockers. These findings are in agreement with the results obtained in isolated atrial and tracheal preparations of the guinea pig.
| 20,392
|
Mixed lymphocyte culture responses in infertile couples.
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Twenty couples suffering from unexplained infertility have been tested in mixed leucocyte culture to determine if the wives were preimmunized against their husbands. The wives were tested against their husbands and four unrelated persons, and thymidine incorporation was measured on the third and fifth days of culture. No evidence was found that would indicate a preimmunization of the wife against her husband as an explanation for their infertility. A slight MLC stimulatory capacity was found in sera from infertile women.
| 20,410
|
The contractile basis of amoeboid movement. V. The control of gelation, solation, and contraction in extracts from Dictyostelium discoideum.
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Motile extracts have been prepared from Dictyostelium discoideum by homogenization and differential centrifugation at 4 degrees C in a stabilization solution (60). These extracts gelled on warming to 25 degrees Celsius and contracted in response to micromolar Ca++ or a pH in excess of 7.0. Optimal gelation occurred in a solution containing 2.5 mM ethylene glycol-bis (beta-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA), 2.5 mM piperazine-N-N'-bis [2-ethane sulfonic acid] (PIPES), 1 mM MgC1(2), 1 mM ATP, and 20 mM KCI at ph 7.0 (relaxation solution), while micromolar levels of Ca++ inhibited gelation. Conditions that solated the gel elicited contraction of extracts containing myosin. This was true regardless of whether chemical (micromolar Ca++, pH >7.0, cytochalasin B, elevated concentrations of KCI, MgC1(2), and sucrose) or physical (pressure, mechanical stress, and cold) means were used to induce solation. Myosin was definitely required for contraction. During Ca++-or pH-elicited contraction: (a) actin, myosin, and a 95,000-dalton polypeptide were concentrated in the contracted extract; (b) the gelation activity was recovered in the material sqeezed out the contracting extract;(c) electron microscopy demonstrated that the number of free, recognizable F-actin filaments increased; (d) the actomyosin MgATPase activity was stimulated by 4- to 10-fold. In the absense of myosin the Dictyostelium extract did not contract, while gelation proceeded normally. During solation of the gel in the absense of myosin: (a) electron microscopy demonstrated that the number of free, recognizable F- actin filaments increased; (b) solation-dependent contraction of the extract and the Ca++-stimulated MgATPase activity were reconstituted by adding puried Dictyostelium myosin. Actin purified from the Dictyostelium extract did not gel (at 2 mg/ml), while low concentrations of actin (0.7-2 mg/ml) that contained several contaminating components underwent rapid Ca++ regulated gelation. These results indicated : (a) gelation in Dictyostelium extracts involves a specific Ca++-sensitive interaction between actin and several other components; (b) myosin is an absolute requirement for contraction of the extract; (c) actin-myosin interactions capable of producing force for movement are prevented in the gel, while solation of the gel by either physical or chemical means results in the release of F-actin capable of interaction with myosin and subsequent contraction. The effectiveness of physical agents in producting contraction suggests that the regulation of contraction by the gel is structural in nature.
| 20,447
|
Early effects of hypervitaminosis A on gluconeogenic activity and amino acid metabolizing enzymes of rat liver.
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In an earlier report from this laboratory, one of the early manifestations of hypervitaminosis A was shown to be a marked stimulation of hepatic gluconeogenesis. In the present study, effects of feeding 30,000 IU of retinyl palmitate to young rats (80-100 g), once daily, for 2 days on the incorporation of 14C-labeled precursors into glucose and glycogen by liver slices, levels of amino acids in blood and tissues, and activities of some important amino acid catabolizing enzymes in the liver were investigated. A stimulation of hepatic gluconeogenesis in hypervitaminosis A was indicated by the increased incorporation of 14C-labeled alanine and bicarbonate into glucose and glycogen by liver slices. Excessive intake of retinol caused a marked increase in the activities of hepatic alanine aminotransferase and ornithine aminotransferase and a decrease in that of tryptophan pyrrolase, without affecting those of tyrosine aminotransferase and serine dehydratase. The ratio of NADH:NAD in the livers of rats fed excess retinol was significantly increased. It is suggested that enhancement of glucoeogenesis in hypervitaminosis A is caused by a stimulation of gluconeogenic activity of the liver.
| 20,486
|
Specific binding sites for a parvovirus, minute virus of mice, on cultured mouse cells.
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The early interactions between parvoviruses and host cells have not been extensively described previously. In this study we have characterized some aspects of viral binding to the cell surface and demonstrated the existence of specific cellular receptor sites for minute virus of mice (MVM) on two murine cell lines that are permissive for viral growth. The interaction had a pH optimum of 7.0 to 7.2, and both the rate and extent of the reactions were slightly affected by temperature. Mouse A-9 cells (L-cell derivative) had approximately 5 X 10(5) specific MVM binding sites per cell, and Friend erythroleukemia cells had 1.5 X 10(5) MVM sites per cell. In contrast, the nonpermissive mouse lymphoid cell line L1210 lacked specific viral receptors. Also, cloned lines of A-9 cells resistant to viral infection have been isolated. One of these lines lacked the "specific" virus attachment sites but exhibited low levels of nonsaturable virus binding. Based on these examples, infectivity is correlated with the presence of specific viral receptors on the cell surface.
| 20,517
|
[Oospora lactis strain actively producing lipase].
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Morphological, cultural and physiological properties of the fungus Oospora lactis producing lipase are described. The activity of lipase depends on the composition of a growth medium, pH, temperature, the duration of cultivation. Optimum conditions for lipase biosynthesis by the fungus have been found. The strain produces extracellular and endocellular lipases during submerged cultivation in the optimum growth medium at a high rate.
| 20,556
|
[Determination of acid-base parameters by means of programmable pocket calculators (author's transl)].
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The possibility to calculate parameters of acid-base status derived by common laboratory devices without built-in computers is described. The calculation is carried out faster and more exactly than it is possible by nomograms, which is especially suitable when a great quantity of dates occurs. The number of programmable steps in some inexpensive pocket calculators is sufficient for this purpose; this type of "microcomputers" offers advantages of economy and small size so that calculations can be carried out immediately at the site where measurements are taken.
| 20,561
|
Aminoacyl-tRNA synthetases from calf liver: optimized assay conditions and kinetic properties.
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Kinetic studies have been performed on the "family" of aminoacyl synthetases from calf liver. All assays were based on the esterification of amino acids to tRNA. Optimized reaction conditions for each synthetase are reported. Most of the synthetases show hyperbolic kinetics with respect to both amino acid and tRNA concentration, however a few show sigmoidal kinetics with respect to one substrate. Arginine, methionine and proline synthetases show sigmoidal kinetics with respect to mixed tRNA solutions and have Hill coefficients of 1.30, 1.10 and 1.20 respectively. Alanine and isoleucine synthetases show sigmoidal kinetics with respect to amino acid concentration and have Hill coefficients of 1.21 and 1.40 respectively.
| 20,569
|
The role of the AT pairs in the acid denaturation of DNA.
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It has been determined previously that the protonation of the GC pairs induces a DNA conformation change which leads to a "metastable" structure. The role of the AT pairs, however, is no well known because the protonation does not modify their spectral properties. By means of an indirect method based on the binding of proflavine, it has been determined that the AT pairs are protonated before the acid-induced denaturation and that they seem to be unable to assume a conformation change when protonated. These results would indicate that the protonated AT pairs may be responsible for the induction of the acid denaturation and not the GC pairs as it was thought previously.
| 20,604
|
Kinetics of drug decomposition. Part 45. Logk--pH profile for rolitetracycline degradation.
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UV spectrophotometry and fluorometry were applied for an examination of rolitetracycline (RT) degradation at pH's ranged from ca 0-8 to 13-0. It was demonstrated that these methods enable to follow the rate of degradation of tetracycline formed in the course of RT hydrolysis. However, they do not allow to monitor the hydrolysis of RT to tetracycline. Application of the so-called "subtraction technique" permits to calculate the rate constants for the total, reversible epimerization reaction and for the subsequent degradation of the resultant products. A rate equation derived for RT degradation in an alkaline medium beginning at pH 10-5 contains a term second-order in the hydroxide ion. Such a relationship was not yet observed in the course of an antibiotic degradation.
| 20,611
|
Purification and properties of a ribonuclease in human urine that hydrolyses polycytidylic acid.
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Human urine RNase was purified about 2000-fold. The preparation is free from phosphatase, phosphodiesterase and DNase activities. On electrophoresis through polyacrylamide gel at pH 8.3, it migrates toward the anode and stains with periodic acid-Schiff reagent, suggesting that it is acidic and glycoprotein in nature. Its isoelectric point is at pH 4.1. It has a molecular weight of about 21,500. It is thermostable at pH 4.2 and thermolabile at pH 8.5. It has a pH optimum at 6.5. It exhibits highest preference for cytidine 3'-phosphate linkages. Its activity on poly (C) is endonucleolytic. It cleaves poly (C) via intramolecular transphosphorylation. It has no action on cytidine 2': 3'-cyclic phosphate or uridine 2':3'-cyclic phosphate. Its rate of hydrolysis of poly (U) is less than 2% of that of poly C). Poly (A) and poly (G) are totally inert to its action. Its action on poly (C) is inhibited by poly (G), poly (A) and poly (U). It differs from bovine pancreatic Rnase A in its physical, chemical and catalytic properties. It is, however, similar to human serum and pancreatic RNase in all its properties, suggesting that pancreas is its likely source.
| 20,615
|
Stimulation of human platelet guanylate cyclase by unsaturated fatty acid peroxides.
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Guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2] activity of human platelet homogenates was stimulated by the addition of phospholipase A2 or unsaturated fatty acids such as oleic, vaccenic, linoleic, linolenic, eicosenoic, eicosadienoic, and arachidonic acids. The addition of lipoxidase potentiated the fatty acid-induced stimulation of guanylate cyclase purified by DEAE-cellulose column chromatography. The extent of the stimulation was dependent on the concentration of the oxidized form of these fatty acids (peroxides). Saturated fatty acids such as stearic and arachidic acids had no effect on the guanylate cyclase activity in the presence or absence of lipoxidase, indicating that human plateletguanylate cyclase is stimulated by unsaturated fatty acid peroxides rather than by fatty acids. Hemoglobin prevented the enzyme stimulation produced by low concentrations of fatty acid peroxides, but enhanced stimulation of the enzyme activity with high concentrations of fatty acid peroxides. 2-Mercaptoethanol, dithiothreitol, and N-ethylmaleimide inhibited the guanylate cyclase activities both in the presence and absence of unsaturated fatty acidperoxide. The stimulation of guanylate cyclase activity by unsaturated fatty acid peroxidesis attributed to oxidation of sulfhydryl residues of the enzyme protein.
| 20,630
|
[The effect of sympathomimetric drugs on exocrine pancreatic function. Studies in the isolated cat pancreas (author's transl)].
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This study reports on effects of beta-sympathomimetic drugs on the exocrine function of the isolated cat pancreas. The injection of these drugs resulted in an increase of pancreatic protein and enzyme secretion, the excretion of calcium into the juice and the rate of volume output were not changed. The enzyme secretion was inhibited by different adrenolytic drugs (phenoxybenzamine, practolol, butoxamine), by tetracain, hemicholinium, and atropine. The pancreatic function of cats pretreated by reserpine or 6-hydroxydopamine was not altered. It is concluded, that beta-sympathomimetic drugs influence the pancreatic protein and enzyme secretion in a cholinergic way. These results are consistent with those of other investigators showing a suppressibility of the isoproterenol-induced pancreatic amylase secretion by atropine.
| 20,653
|
[Characteristics of the ecology of the eastern equine encephalomyelitis virus in the Republic of Cuba].
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Virologic and serological surveys of wild vertebrates carried out in various provinces of Cuba demonstrated definitely that birds were the main hosts of eastern equine encephalomyelitis (EEE) virus in this territory. Fifteen strains of this virus were isolated from 8 species of birds belonging to 5 orders. Isolation of EEE virus from the blood of the endemic genus of iguanas indicates a certain role of cold-blooded animals in the ecology of this agent. Active EEE virus foci have been found in 4 provinces of the Republic of Cuba: Pinar del Rio, Havana, Matanzas and Las Villas. Isolation of a number of EEE virus strains from sick horses during an epizootic in the latter province confirmed the importance role of this agent in the infectious pathology of domestic animals in Cuba. The experimental results suggest that in Cuba there occur at least two types of foci of this infection: forest and water-littoral (fresh-water swamps and lakes, and sea coast with mangrove forests).
| 20,693
|
Gamma-radiolysis of aqueous solution of histidine.
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The dependence of Gi(-M) values of histidine on the concentration of irradiated 10(-4) - 10(-1)M solutions, pH and the presence of O2, N2O and sec-butyl alcohol was investigated. In oxygen-free medium the maximum radiation sensitivity of histidine was found at pH 5--8; in oxygenated solutions it was shifted to the 6--1 pH range. The formation of radiation products was also studied. The course of radiation decomposition of histidine depends on the presence of oxygen and on the pH of irradiated solution.
| 20,705
|
Diazepam and flunitrazepam as induction agents for cardiac surgical operations.
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Diazepam and flunitrazepam were compared in equipotent doses as induction agents for premedicated patients having cardiac surgery. Both drugs caused a significant fall in arterial blood pressure, a rise in Paco2 and a fall in Pao2. There was no significant difference between the two drugs in onset time of anaesthesia, cardiovascular or respiratory depression, or quality of induction. There was also no significant difference from induction with thiopentone in these respects. Diazepam, over a 0.2 to 0.6 mg/kg range of doses showed no difference in toxicity, although induction was clinically smoother with the higher dose.
| 20,727
|
Protected proteins in ruminant nutrition. In vitro evaluation of casein derivatives.
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Chemical treatment of proteins in feeds can, by crosslinking protein chains or other chemical effects, decrease their solubility and microbial degradation in the rumen. A need exists to modify proteins systematically under well-defined conditions with inexpensive reagents and to evaluate the treated products nutritionally for possible beneficial effects on wool growth and quality as well as production of meat and milk. As a first step toward this goal we evaluated many derivatives of casein treated at pH 9-10 with various acylating and alkylating agents. Initial tests indicate that all treatments decreased protein digestion by rumen microorganisms. Potentially crosslinking reagents are usually more effective than similar ones that cannot crosslink. A few treatments gave ruminal protection that approached or exceeded that obtained with formaldehyde. This result shows that systematic evaluation of ruminal in vitro digestibility of protein derivatives may disclose new products deserving tests of post-ruminal digestibility and practical nutritive value.
| 20,754
|
[Continuity of life situation and "successful" aging (author's transl)].
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The determinants of "successful" aging have been a main concern in social gerontological research. The Continuity Hypothesis suggests that there is a relationship between an older person's life satisfaction and the similarity of his social life situation in middle adulthood and in old age. The old person is the more likely to score low in life satisfaction the less similar his old age situation to his life situation in middle adulthood. This hypothesis has been tested in summer 1973 in Cologne with a sample of 406 people aged 65 and over. Findings indicate that continuity of life situation may be an important variable accounting for life satisfaction in old age. Moreover, it could be shown that the various negatively experienced life changes since adulthoood formed a complex of interacting variables, thereby increasing the negative effect on the old person's life satisfaction. Health proved to be one of the most important variables. The continuity hypothesis as stated here represents a modified version of activity theory.
| 20,790
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[Importance of space analysis of U-moment-vectors concerning ageing people and chronical heart and blood circulation diseases (author's transl)].
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U-vectors are a stabil component of electric activity of the heart repolarisation. The examinations of the space sizes and direction of the U-moment-vectors give an idea about the character of repolarisation of Purkinje's fibres and papillar muscles in old age and in chronical heart and blood circulation diseases. Pathological alteration of the U-vectors appear sooner and are more explicit than the T-vectors.
| 20,802
|
[Morphological changes of the female urinary bladder in the elderly. Chronic infections of the urinary tract; the importance of their intensive treatment as preparatory measure for rehabilitation (author's transl)].
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The urinary bladder of the elderly is showing a reduced adaptability on account of morphological changes; it is therefore more prone to infections. The morphological changes consist in a reduction of muscle fibres and in an increase of collagen fibres and in elastosis, furthermore in a sklerosis of the intramural arteries. 58% of our chronically - ill patients prove to have a chronic infection of the urinary tract.
| 20,805
|
Experimental cryptorchidism in adult male rats: histological and hormonal sequelae.
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Mature male rats were rendered cryptorchid and followed for up to nine weeks during which serial blood specimens were obtained for multiple hormonal analyses; serial testicular samples were obtained as well. In contrast with control animals, cryptorchid rats showed transient rises in FSH which returned to normal at the end of the study; estrogen levels were high in the final weeks. Plasma testosterone levels were unchanged and LH levels changed little. Light and electron microscopic studies of testicular biopsy specimens showed prompt disruption of spermatogenesis which became more extensive with time. Sertoli cells underwent multiple changes including increased lipid storage and phagocytosis of spermatozoa. Comparisons are made between the sequence of hormonal changes and that of histological changes. In addition, questions are raised concerning the ways in which Sertoli cells are affected by experimental cryptorchidism.
| 20,820
|
Cilioinhibitory effect of phenothiazines in vitro and its antagonism by Ca++.
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The inhibition of ciliary beating in vitro by physiologic concentrations of chlorpromazine (CPZ) and prochlorperazine (PCP) was demonstrated in two experimental systems. CPZ had a greater cilioinhibitory effect than PCP on the rotational velocity of tissue explants from the frog palate in amphibian Ringers, and on the frequency of ciliary beating in rat tracheal rings in culture medium. Addition of calcium acetate in equal molarity to CPZ, within a time limit dependent on the drug concentration, reversed this inhibition, while dibutyryl cyclic AMP did not. Simultaneous addition of Ca++ and CPZ slowed down, but did not stop, this ciliostasis, while priming with Ca++ or cyclic AMP prior to drug addition had less of an effect. These data lend support to a prevalent theory that CPZ exerts its actions by displacing calcium ions from membrane sites.
| 20,858
|
The effect of inorganic phosphate on cyanogenesis by Pseudomonas aeruginosa.
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The biosynthesis of hydrogen cyanide (HCN) by a strain of Pseudomonas aeruginosa is found to be significantly influenced by inorganic phosphate. Optimum HCN production occurs when the phosphate concentration is between 1 and 10 mM. Above and below this concentration the amount of HCN produced decreases sharply and at 0.1 and 100 mM phosphate low HCN production occurs. If a culture growing at 0.1 mM phosphate and producing low HCN is shifted to 10 mM phosphate, HCN biosynthesis resumes. Experiments with chloramphenicol indicate that de novo-protein synthesis is required for the process.
| 20,863
|
An NADP-linked acetoacetyl CoA reductase from Zoogloea ramigera.
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Zoogloea ramigera I-16 M was found to contain two stereospecific acetoacetyl CoA reductases; one was NADP+-linked and D(-)-beta-hydroxybutyryl CoA specific and the other was NAD+-linked and L(+)-isomer specific. The NADP+-linked enzyme, purified approximately 150-fold, had a pH optimum for the reduction of acetoacetyl CoA at 8.1, but no definite pH optimum for the oxidation for beta-hydroxybutyryl CoA. The apparent Michaelis constants for acetoacetyl CoA and NADPH were 8.3 and 21 micrometer, respectively. The enzyme was markedly inhibited by acetoacetyl CoA at concentrations higher than 10 micrometer. The incorporation of [1-14C]acetyl CoA into poly-beta-hydroxybutyrate (PHB) by bacterial crude extract (containing beta-ketothiolase, acetoacetyl CoA reductases, enoyl CoA hydratases and PHB synthases) or by a system reconstituted from purified preparations of beta-ketothiolase, acetoacetyl CoA reductase and PHB synthase, was observed only in the presence of NADPH, but not NADH. Among various enzymes involved in PHB metabolism, only the specific activity of glucose 6-phosphate dehydrogenase was elevated 5-fold within 2 h after the addition of glucose to the cells grown in the basal medium. These findings suggest that, in Z. ramigera I-16M, acetoacetyl CoA is directly reduced to D(-)-beta-hydroxybutyryl CoA by the NADP+-dependent reductase, and PHB synthesis is at least partially controled by NADPH availability through glucose 6-phosphate dehydrogenase.
| 20,866
|
[Determination of the KM-value of the fumarase (E.C. 4.2.1.2) with bencyclan-hydrogenfumarate as the substrate (author's transl)].
|
The Michaelis-Menten constant for fumarase (E.C. 4.2.1.2) has been determined by measuring the enzyme activity by the spectrophotometric method of Racker, which depends on the formation or disappearance of the double bond of fumaric acid. When using Na2-fumarate or bencyclan hydrogenfumarate (Fludilat), respectively, as a substrate, a KM-value of 1.3 X 10(-3) M was found for both substances. In a linked assay where the formation of NADH in the reaction of fumarate leads to malate leads to oxaloacetate was used as a parameter for the reaction rate, a KM-value of 1.35 X 10(-3) M was found.
| 20,899
|
A spectrofluorometric method for the determination of ajmaline in plasma.
|
1 Ajmaline was found to have maximum fluorescence at neutral pH with 300 nm excitation and 365 nm emission wavelengths (corrected). 2 The fluorescence intensity had a linear relationship to concentration up to 50 microgram ml-1 and the recovery of ajmaline after extraction from plasma was 92.5 +/- 3%. 3 Extraction of drug-free plasma and of samples containing known concentrations of ajmaline showed that drug levels in the range found clinically could be measured accurately by fluorimetry. 4 Serial plasma ajmaline concentrations were measured in a subject after intravenous injection of ajmaline (50 mg). The rates of plasma clearance of the drug were found to be similar to those obtained in previous studies.
| 20,915
|
Site of bicarbonate effect in Hill reaction. Evidence from the use of artificial electron acceptors and donors.
|
Using artificial electron donors and acceptors, it is shown here that the major HCO3- effect in the Hill reaction is after the "primary" electron acceptor (Q) of Photosystem II and before the site of action of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (at the plastoquinone pool). Chloroplasts in the presence of both 3-(3',4'-dichlorophenyl)-1,1-dimethylurea, which blocks electron flow from the reduced primary acdeptor Q- to the plastoquinone pool, and silicomolybdate, which accepts electrons from Q-, show no significant bicarbonate stimulation of electron flow. However, a 6-7 fold stimulation is clearly observed when oxidized diaminodurene, as an electron acceptor, and dibromothymoquinone, as an inhibitor of electron flow beyond the plastoquinone pool, are used. In the same chloroplast preparation no measurable effect of bicarbonate is observed in a Photosystem I reaction as monitored by electron flow from reduced diaminodurene to methyl viologen in the presence of 3- (3',4'-dichlorophenyl)-1,1-dimethylurea. The insensitivity of the bicarbonate effect to uncouplers of photophosphorylation and the dependence of this effect on the presence of a weak acid anion and on external pH are also reported.
| 20,948
|
Resonance Raman study of the pH-dependent and detergent-induced structural alterations in the heme moiety of Rhodospirillum rubrum cytochrome c'.
|
The resonance Raman spectra and the structures of the heme moiety of Rhodospirillum rubrum cytochrome c' were investigated for its five states characterized by absorption spectra; Types-a and -n of the reduced form and Types-I, -II, and -III of the oxidized form. The frequency of the ligand-sensitive Raman line suggested the coordination of lysine (Nepsilon) at the sixth position of the heme iron of Type-n. The sixth ligand of Type-III was deduced to be either lysine or histidine but would not be methionine. Type-a and Type-II gave the Raman spectra of rather normal high spin type but Type-I was unusual in the sense that the frequencies of the Raman lines associated primarily with methine-bridge CC-stretching vibrations were relatively high in comparison with those of other high spin hemoproteins. Type-I was converted directly to Type-III upon the addition of SDS or 2-propanol but the conversion occurred via Type-II when pH was increased. Structural difference between the high spin hemes of Type-I and Type-II was discussed in detail.
| 20,977
|
[Functional role of parvalbumins in regulating Ca2+ in the contraction--relaxation cycle of vertebrate skeletal muscles].
|
On the basis of parvalbumin property to change Ca2+-binding constant within the pH-region from approxim-tely 7 to approximately 8 a hypothesis that parvalbumins are pH-regulated Ca2+-depot in muscles has been stated. The addition of parvalbumin to native actomysin complex at pH approximately 7 in the presence of ATP and Ca2+ results in partial inhibition of its superprecipitation. The change of pH up to approximately 8 leads to the restoration of actomyosin superprecipitation.
| 20,987
|
[Effects of nucleophils on kinetic parameters of peroxidase-catalyzed oxidative reactions].
|
The effect of imidazole on the kinetic parameters of reactions of potassium ferrocyanide and o-dianizidine peroxidation by hydrogen peroxide within a wide range of pH was studied. It was shown that imidazole activates the reaction of o-dianizidine peroxidation at pH greater than or equal to 6.5, but does not affect the oxidation of potassium ferrocyanide. It was also found that imidazole causes a similar increase in the kkat and Km, i. e. non-competitive activation occurs. The data obtained suggest a possible mechanism of the activator effect. Differences in the mechanism of interaction of various substrates uith peroxidase are discussed.
| 20,996
|
[Proteins of Bacillus thuringiensis delta-endotoxin crystals].
|
Pure crystals (at least 99% purification) of sigma-endotoxin were isolated from Bac. thuringiensis var. galleriae. The complete dissolution of crystals might be achieved by the increase of pH up to 12 and higher or by a combined action of S = S-reducing and denaturing agents. Electrophoresis of the solubilized crystal proteins in 5% polyacrylamide gels containing 0,1% sodium dodecyl sulfate and 8 M urea reveals two major bands corresponding to molecular weights of 120000--140000 (65%) and 65000 (8-10%), and some minor components whose molecular weights varied from 65000 to 340000. Urea (3--8 M) causes to partial dissolution of the crystals; the component with molecular weight of 65000 is mainly found in the solution (component A). In dithioerythritol extracts at pH 9 the major component of the crystal is the protein with molecular weight 120000--140000 (component B). The crystals, alkali-soluble components and proteins isolated from crystals by selective extraction (3--8 M urea or 0.01 M dithioerythrytol, pH 9) were found toxic for the larvae of Galleria mellonella.
| 21,000
|
Attitude change during behavioural treatment of sexual inadequacy.
|
Attitudes towards 'self' and 'partner' were studied in couples undergoing three different behavioural treatments for sexual inadequacy: systematic desensitization with counselling; guided practice with counselling; and practice with minimal counselling. Factor analysis of semantic differential scales identified five components--general evaluation, anxiety, and three factors relevant to sexual evaluation designated as 'loving', 'sexually attractive' and 'easy to arouse'. Differences in derived factor scores were found which related to sex of rater, identity of complainant, and treatment received; with the treatment combining guided practice with counselling being followed by significantly greater attitude changes.
| 21,015
|
Clinical usefulness of alkaline phosphatase isoenzyme determinations.
|
1. We report on the clinical usefulness of alkaline phosphatase isoenzyme determinations using a combined chemical inhibition method on 731 patient serum specimens exhibiting elevated (greater than 350 U/L) alkaline phosphatase (AP) activity. 2. The relative percentages of the organ-specific alkaline phosphatase activities were computed on the basis of three independent assays: total activity, activity in the presence of 10 mMl-phenylalanine, and activity in the presence of 3.1 M urea. 3. Gamma-glutamyl transferase (GGT) activity assays were also performed on the same specimens. Using an upper reference limit of 30 U/L for GGT and comparing the GGT results with the percent liver AP, we found that the GGT results were 91% sensitive and 60% specific. 4. We conclude that AP isoenzyme determinations are very useful in identifying the organ source(s) responsible for elevated AP values. 5. The reference ranges for several age groups in relation to the adult population and their significance are presented.
| 21,038
|
Prostatic binding protein. A steriod-binding protein secreted by rat prostate.
|
Rat prostatic cytosol contains a high concentration of a prostatic binding protein with peculiar steroid-binding properties. Indeed, in spite of a relatively low affinity, charcoal adsorption can be used for its measurement. Furthermore, the binding is not specific for particular steroids and increases very strongly after delipidation. In delipidated cytosol the concentration of the binding site is 3.1 micronmol/g protein and the apparent affinity for pregenolone 1.7 X 10(6) M-1. The high concentration of prostatic binding protein in prostatic fluid shows that this substance is secreted by the prostate. Prostatic binding protein has the following physicochemical characteristics: it is precipitated by ammonium sulfate between 50 and 70% saturation; the elution position from a Sephadex G-100 column corresponds to a molecular weight of 51000; it sediments in sucrose density gradients at 3.7 S and is eluted from DEAE-cellulose columns at about 0.25 M KCl. On polyacrylamide gel electrophoresis the binding activity coincides with the major cytosolic protein band. This band has the same mobility as serum albumin in 7% gels, but a higher mobility in more concentrated gels.
| 21,076
|
A new factor from enteric bacteria of rats amplifying induction of liver enzyme by glucocorticoid. 2. Mechanism of action.
|
1. An amplifier of the action of glucocorticoid was purified from Proteus mirabilis as described previously. It was found that it amplified the induction of liver tyrosine aminotransferase by dexamethasone markedly with doses of dexamethasone that caused minimal enzyme induction, but had little effect with doses that caused maximal induction. Thus the amplification may represent a saving of glucocorticoid. The amplification of enzyme activity was brought about by increase in amount of enzyme. 2. The amplification was observed when the amplifier was administered before or with dexamethasone, but not when it was given 2 h after dexamethasone. These results and the finding that actinomycin D inhibited the amplification indicate that the amplifier does not act on the translational level of enzyme induction. 3. It was found that the amplifier increased both incorporation of [3H]dexamethasone into the cytosol and binding of [3H]dexamethasone of cytosol protein and that it decreased decay of the [3H]dexamethasone-protein complex.
| 21,084
|
Ionization behaviour of native apolipoproteins and of their complexes with lecithin. 1. Calorimetric and potentiometric titration of the native apoA-I protein and of the apoA-I protein-dimyristoyl lecithin complex.
|
The ionization behaviour of native apoA-I protein is compare to that of its complex with synthetic dimyristoyl lecithin in studies using calorimetric, potentiometric and spectrophotometric titration. In the presence of phospholipids, 10 out of 21 lysines together with 22 acidic residues are masked in the complex. All tyrosines remain accessible to titration below pH 13. The apparent ionization enthalpy of the 11 lysine residues is not affected by the presence of phospholipids. These data are consistent with discrete binding sites located in the apoprotein helical segments as suggested by the model of Segrest et al. [FEBS Lett. 38, 247-253 (1974)]. A tentative localisation of lysine, arginine, aspartic acid and glutamic acid residues directly involved in phospholipid binding is suggested, assuming that such helical regions are involved in apoprotein-phospholipid association.
| 21,089
|
The structure and function of ribonuclease T1 XXIV. Preparation and properties of a stable water-insoluble polyacrylamide derivative of ribonuclease T1.
|
Ribonuclease T1 [EC 3.1.4.8] was coupled to a water-insoluble cross-linked polyacrylamide (Enzacryl AH) by the acid azide method. The immobilized enzyme exhibited about 45% and 77% of the original activity toward yeast RNA and 2', 3-cyclic GMP, respectively, as substrates. Although the specific activity was lowered by the coupling, the immobilized enzyme was found to be far more stable to heat and extremes of PH than the native enzyme. The immobilized enzyme was active toward RNA even above pH 9 (at 37 degree C) or above 60 degree C (at pH 7.5), where the native enzyme was inactive. The immobilized enzyme retained much of its activity as assayed at 37 degree C after incubation in the range of pH 1 to 10 at 37 degree C, or after heating at 100 degree C (at pH 7.5) under conditions where the native enzyme was inactivated to a considerable extent. The enzyme derivative could be repeatedly recovered and reused without much loss of activity. The active site glutamic acid-58 in the immobilized enzyme appeared to be nearly as reactive with iodoacetate as that in the native enzyme.
| 21,179
|
Studies of the beta-galactoside transporter in inverted membrane vesicles of Escherichia coli. I. Symmetrical facilitated diffusion and proton gradient-coupled transport.
|
Facilitated diffusion of [14C]lactose into inverted membrane vesicles of Escherichia coli was measured using HgCl2 as a stopping reagent and polylysine to flocculate the vesicles for filtration. Equilibration of lactose between the internal and external volumes required expression of the y gene of the lac operon and was inhibited by thiodigalactoside or by prior incubation with N-ethylmaleimde or HgCl2. The initial rate of uptake was saturable, with a Kt of 0.95 mM. Counterflow of [14C]lactose was demonstrated in either direction. ATP hydrolysis or respiration drove the efflux of internal lactose. The effect of ATP required addition of F1 coupling factor (ATPase) from E. coli when lactose transport was studied in F1-deficient inverted vesicles. Accumulation of lactose against a concentration gradient was achieved by forming an artificial electrochemical proton gradient consisting of a membrane potential negative inside or a pH gradient basic inside. Addition of ATP inhibited this proton driven uptake showing that it occurred in inverted vesicles. It was concluded that the lactose-proton co-transport protein (M protein) is qualitatively symmetrical with respect to the facilitated diffusion of lactose and the coupling of proton and lactose transport.
| 21,183
|
Nicotinamide adenine dinucleotide-specific glutamate dehydrogenase of Neurospora. IV. The COOH-terminal 669 residues of the peptide chain; comparison with other glutamate dehydrogenases.
|
A sequence is presented for the COOH-terminal 669 residues of the NAD-specific glutamate dehydrogenase of Neurospora crassa. Comparison of this sequence with those of the vertebrate glutamate dehydrogenases of chicken and bovine liver and with the NADP-specific enzyme of Neurospora shows some similarities in sequences around residues previously identified as important for the function of these enzymes. These are: (a) the reactive lysine residue of low pK in the NADP and the vertebrate enzymes; (b) the tyrosine residue of the NADP enzyme that is readily nitrated by tetranitromethane with inactivation, a residue protected by NADP or by NMN; and (c) the arginine residue of the NADP-enzyme that is reactive with 1,2-cyclohexanedione with inactivation. Despite these similarities, comparison of the sequence of the NAD-enzyme with those of the other glutamate dehydrogenases of known sequences revealed relatively little overall homology as determined by computer analysis.
| 21,191
|
Adsorption of horseradish peroxidase, ovomucoid and anti-immunoglobulin to colloidal gold for the indirect detection of concanavalin A, wheat germ agglutinin and goat anti-human immunoglobulin G on cell surfaces at the electron microscopic level: a new method, theory and application.
|
A method is described for the adsorption of selected macromolecules to colloidal gold which is then used as an electron dense marker for the indirect detection of specific cell surface molecules. Membrane bound concanavalin A, which binds specific sugars on horseradish peroxidase, and wheat germ agglutinin, which binds specific sugars on ovomucoid are detected indirectly with gold labeled horseradish peroxidase and ovomucoid, respectively. Goat anti-human IgM on blood lymphocytes is detected with gold labeled rabbit anti-goat IgG. In the preparation of colloidal gold labeled proteins, the problems of flocculation of colloidal gold by proteins and nonadsorption of proteins to colloidal gold, are solved through a combination of concentration of protein and pH variable adsorption isotherms, which allows one to determine the conditions for adsorption of proteins to colloidal gold. Adsorption is pH dependent, the pH conditions correlating with the isoelectric point(s) of the major protein fraction(s); adsorption is influenced by interfacial tension, solubility and by the electrical charge on the molecules. Colloidal gold is inexpensive and preparation of a useful label is rapid, reproducible and the results easily quantitated from electron micrographs.
| 21,217
|
A comparison of the dissolution rates of caffeine tablets in a rotating-basket with those in a Sartorius dissolution tester.
|
Uncoated caffeine tablets of four different hardnesses were tested for dissolution rate by the Sartorius (S.S. method) and by the rotating basket method of the U.S.P. XVIII. In both methods the dissolution rate decreased with increasing hardness, and the rate obtained with the S.S. method was always less than that by the U.S.P. method. This result cannot be explained as being due only to the difference in the volume of dissolution medium. Also it was difficult to ensure that the characteristic changes in the process of dissolution paralleled the curves obtained from a plot of % caffeine dissolved vs time. Accordingly, the dissolution rate constants were calculated from the slope of each straight line in a plot of ln W infinity/(W infinity --W) vs time.
| 21,235
|
Biochemical and pharmacological studies on amineptine (S 1694) and (+)-amphetamine in the rat.
|
The pharmacological activities of amineptine (S 1694) and (+)-amphetamine and their interaction with biogenic amines have been examined in rats. The locomotor activity, stereotyped behaviour and hypothermia induced by amineptine were similar to but not as marked as those produced by (+)-amphetamine, and there was little or no anorectic action. Amineptine does not modify the concentrations of brain noradrenaline or acetylcholine which are respectively reduced and increased by (+)-amphetamine. Moreover, amineptine does not affect significantly the decrease of brain noradrenaline induced by an intraventricular injection of 6-hydroxydopamine, an effect significantly antagonized by (+)-amphetamine. On the other hand, like amphetamine, amineptine significantly reduces the effect of 6-hydroxy-dopamine on brain dopamine. Both drugs increase the striatal concentrations of homovanillic acid and show a cross tolerance in this action. Therefore they could act similarly on the striatal dopaminergine system. Amineptine thus appears to be a new type of antidepressant with a brain biochemical profile differing from that of other drugs used in depressive disorders.
| 21,261
|
Monoamine oxidase and catechol-O-methyl transferase activity in Tetrahymena.
|
Tetrahymena pyriformis strain HSM was found to have monomine oxidase (MAO) and a catechol-3-methyl transferase-like (COMT) activity. As in mammalian tissues, the MAO activity is predominantly localized in the mitochondrial pellet and COMT in the cytosol. The COMT-like activity was present in amounts comparable to several mouse tissues and was inhibited by tropolone. MAO activity was much lower than in any of the mouse tissues tested, and its activity varied greatly from preparation to preparation. The substrate preference of Tetrahymena MAO was tryptamine greater than serotonin greater than dopamine, and activity increased with increasing pH from pH 6.5 to pH 7.8, as does that of mouse liver MAO. Teh Km of Tetrahymena MAO for tryptamine was approximately 4 micrometer, an order of magnitude lower than that of mouse liver MAO. Sensitivity of inhibition by MAO inhibitors was variable. In some preparations, no inhibition was observed. In others clear inhibition was obtained, harmine and clorgyline being among the most potent inhibitors.
| 21,289
|
Synthesis and pharmacological activity of some N-alkyl-substituted 9alpha-ethyl-2'-hydroxy-5-methyl-6,7-benzomorphans.
|
A series of N-substituted 9alpha-ethyl-2'-hydroxy-5-methyl-6,7-benzomorphans was synthesized and evaluated for their narcotic analgesic and antagonistic activities. Compounds 2a and 22 were as potent as morphine in the writhing (PPQ) and hot-plate tests, while a number of compounds demonstrated antagonistic activities greater than nalorphine. Generally, the compounds in this series show activities somewhat greater than the comparable compounds in the 5,9alpha-dimethyl-6,7-benzomorphan series for analgesic effect and similar or slightly less antagonistic potency.
| 21,291
|
Bilateral seminoma 34 years after orchiopexy.
|
A case of bilateral seminoma in a 59-year-old patient who had undergone bilateral orchiopexy 34 years previously is presented. To our knowledge this is the longest interval between an orchiopexy and diagnosis of bilateral malignancy.
| 21,310
|
[Evaluation of antireflux effect of fundic patch operation by withdrawal pH curve (author's transl)].
|
With the use of gastroesophageal withdrawal pH curve, pathophysiology after various surgical procedures for achalasia of the esophagus was investigated experimentally from the view point of postoperative reflux. A total of 68 dogs were divided into four groups and were prepared with proximal gastrectomy with end-to-end esophagogastrostomy, Wendel procedure, Heller procedure and Fundic patch operation, respectively. In the group with Fundic patch operation, efficacy of the flap valve, mucosal valve and fundoplication was also evaluated preparing them in various sizes. The results obtained may be summarized as follows: 1) Withdrawal pH measurement is a sentive mean to detect the gastroesophageal reflux. 2) Proximal gastrectomy with end-to-end esophagogastrostomy and Wendel procedure yielded worst results with severe gastroesophageal reflux. On the contrary, Fundic patch operation best controlled the gastroesophageal reflux. 3) Gastroesophageal reflux could be prevented by the Fundic patch operation with the flap valve 6 cm in length and fundoplication enclosing around 1/2 to 2/3 circumference of the distal esophagus.
| 21,321
|
Arginine esterase and lysosomal hydrolases in liver from cystic fibrosis subjects.
|
The total activity and isoelectric focusing patterns of arginine esterase, cathepsin B1, and several lysosomal hydrolases were normal in liver from two patients with cystic fibrosis. No abnormalities were observed in values for pH optimum, Km, and Vmax for arginine esterase and cathepsin B1 in liver from cystic fibrosis patients compared to those values for liver from the control subject. Soybean trypsin inhibitor at concentrations up to 100 microgram/ml had no effect on liver arginine esterase or cathepsin B1.
| 21,378
|
[Septicemia in the elderly (author's transl)].
|
Out of 1,251 patients above 65 years of age staying at the Charles Foix Hospital (prolonged hospitalization) and the St. Joseph Hospital (acute cases), 168 had one or more positive blood cultures. Urinary tract infection is a major source of septicemia due to gram negative bacilli. It is important to stress cases of septicemia due to pneumococcal pneumoniae, eschars, and other skin lesions. Mortality varies between 33 and 36%, depending upon the hospital. Collapse, although infrequent, still portends a grave prognosis (61% of cases of collapse led to death at Charles Foix Hospital). The combination of more than two risk factors considerably worsens the prognosis. Hypoproteinemia and dementia are every bit as grave as diabetes and cancer. A better isolation of the microorganisms involved in cases of septicemia in the elderly will lead to a more judicious choice of antibiotics. The administration of chemotherapy immediately after the samples were obtained remains the main guarantee of successful therapy.
| 21,383
|
Gastro-oesophageal acid reflux in patients with symptomatic hiatus hernia and effect of a modified Belsey MK IV repair on acid reflux.
|
Twelve-hour continuous recording of pH at the distal end of the oesophagus was carried out in 59 patients with sliding hiatus hernia and symptoms suggestive of gastro-oesophageal reflux, and the results were compared with those obtained in normal subjects. Mean duration of pH less than or equal to 2.3, pH less than or equal to 3, pH less than or equal to 4 and pH less than or equal to 5, expressed in percentages of the total time of recording, was longer in patients than in normal subjects. There was no difference in mean number of reflux episodes between patients and normal subjects. The clearest separation between the two groups was obtained by the variable 'duration of pH less than or equal to 5'. Irrespective of the variable used, the results did not seem to be related to the degree of severity of the symptoms. Individual sensitivity of the oesophageal mucosa, the content of bilious components in the refluxed material, and the semi-quantitative character of the investigation may, in part, account for the results. Furthermore, the same investigation was carried out before and three months after a modified Belsey MK IV repair in 39 patients with hiatus hernia and symptoms indicating surgical treatment. The operation was followed by a reduction in the tendency to acid reflux, probably as a result of an increase in the competence of the gastro-oesophageal region.
| 21,444
|
Deuterolysis of amino acid precursors: evidence for hydrogen cyanide polymers as protein ancestors.
|
Deuterolysis experiments suggest that hydrogen cyanide polymers rather than aminoacetonitriles are major precursors of alpha-amino acids obtained from spark reactions and other studies on chemical evolution. These results are consistent with the hypothesis that the original heteropolypeptides on the earth were synthesized spontaneously from hydrogen cyanide and water without the intervening formation of alpha-amino acids.
| 21,452
|
Splenic-gonadal fusion and adrenal cortical rest associated with bilateral cryptorchism.
|
A patient with bilateral cryptorchism had ectopic splenic tissue adherent to his left testicle and an adrenal cortical rest adherent to his right testicle. The embrylogic basis for these disorders is discussed and the literature reviewed.
| 21,481
|
[Role of autoimmune processes in the pathogenesis of post-vaccinal lesions of the nervous system].
|
Subcutaneous sensitization of guinea pigs with -vaccine, and also an intracardiac injection of smallpox or measles vaccine induced production of brain autoantibodies, whereas subcutaneous or intradermal immunization of the animals with liver viral vaccines was not accompanied by the formation of autoantibodies and development of the pathological processes in the nervous system tissue. tthe greatest changes in the brain tissue in the form of circulatory disturbances and inflammatory-dystrophic phenomena in combination with high autoantibody titres in the blood were noted in intracardiac injection of smallpox vaccine and in subturbancessensitization with AK-Vaccine and the least (short-term circulatory disturbances, transitory signs of serous meningitis and neuron dystrophy against the background of low blood auto anitbody content)--in intracardiac injection of measles vaccine. Administration of live viral vaccines into the circulation of animals against the background of their sensitization with -vaccine led to reduction of blood autoantibody level coinciding in time with the periods of marked pathomorphological changes in the brain tissue.
| 21,500
|
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