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PubMed1977

[Cytochemical studies of ultrathin frozen sections of blood platelets].

Results obtained by conventional techniques and freeze-ultramicrotomie have been compared. Ultrathin frozen sections of platelets, which are fixed by glutaraldehyde, freeze-protected by polyvinyl-pyrrolidone and encapsulated in gelatin show a well preserved fine structure after staining with buffered OsO4, phosphotungstic, phosphomolybdic or ammoniummolybdic acid. The preservation of polysaccharides or mucopolysaccharides depends on a suitable fixation, that of glycogen in certain cases depends on a double fixation (glutaraldehyde and OsO4). Cytoplasmic nucleoproteins like ribosomes are visible only after drying of sections and staining with uranyl-acetate. Lipids, both membrane lipoproteins as well as lipids in the matrices of cell organelles, are well preserved. For example the zinc-iodide osmiumtetroxide reaction yields positive results in frozen sections contrary to such obtained by conventional methods. Furthermore, the extraction of altered lipids after staining with dyes like acridine orange does not take place with this method. For this reasons the freeze-ultramicrotomy seems to be an useful alternative method.

Animals↗
PubMed1973

Evaluation of a simple preservative for bacteriological tests on urine.

A urine preservative containing NaCl and polyvinyl-pyrrolidone has been in general use at this hospital for three years. It enables the specimen to be held at room temperature for 48 hours or more without appreciable change in the content of viable bacteria. The results of bacteriological tests performed on 2452 preserved urine specimens are compared with those from a control series examined before the method was introduced. A marked improvement in accuracy is demonstrated. The preservative can be very easily and cheaply prepared in any laboratory.

Bacteriological Techniques↗
PubMed1975

Coagulation, hemostasis, and plasma expanders:a quarter century enigma.

Despite more than 2 decades of research, the explanation of the long-known hemostatic failure consequent to the use of some natural and synthetic macromolecular agents as plasma substitutes remains obscure. Conventional clotting parameters are not significantly affected in vivo or in vitro. Dextran, hydroxyethyl starch, and many other colloid macromolecules precipitate Factors I and VIII, fibrin monomer, and perhaps v. W. (von Willebrand) factor(s) from plasma, rendering at least the first three insoluble, in relation to the molecule size and concentration of the colloid, and for dextran, its intrinsic viscosity. The precipitate, rich in Factors VIII and I, redissolves on warming, and reprecipitates on cooling, behaving as a cryo-Factor I. In composition it closely resembles the cryoprecipitate obtained by slow-thawing of plasma. Both clot faster with thrombin than the parent plasma. The amount precipitated from plasma by dextran or hydroxyethyl starch varies very widely from individual to individual. Cryo- of dextran-precipitable material can be obtained by interacting purified Factor I with a miniscule amount of thrombin. Dextran, hydroxyethyl starch, polyvinyl pyrrolidone, some forms of gelatin, and several polyamino acids accelerate thrombin clotting of normal plasma, several dysfibrinogenemic plasmas, or Factor I. Albumin, hemoglobin, some modified gelatins do not. Poor platelet thromboplastic function appears some hours after dextran infusion, associated with morphologic capillary abnormalities that strikingly resemble those in v. W. disease. We postulate that the hemostatic defect associated with the use of plasma substitutes is a form of induced v. W. disease or disseminated intravascular clotting, ensuing from precipitation and removal of v. W. factor(s), Factors VIII and I, microcirculatory abnormality, and platelet malfunction. The latter two supervene some time after administration of dextran. It reported antithrombotic activity is perhaps referable to the same action.

Adolescent↗
PubMed1973

Mechanisms of interhemispheric transfer of visual information in rats.

Pattern discrimination learning in functionally hemidecorticate rats leads to formation of memory traces in the intact hemisphere. The interhemispheric transfer (IHT) of such lateralized engrams is more efficient when the untrained eye rather than the trained eye is used during interdepression training (10 trials) preceding the retention test with the contralateral hemisphere, probably because the untrained hemisphere is indispensable for readout in the first case (imperative IHT) but can be completely bypassed in the second case (facultative IHT). Monocular acquisition of a pattern discrimination habit induces a strong primary engram in the contralateral and a weak secondary engram in the ipsilateral hemicortex. The primary trace is further improved with overtraining while the secondary engram is abolished. During interocular transfer, the primary trace is at first read out through commissural fibers while a secondary trace is rapidly transferred to the untrained hemisphere. Pretraining administration of 2-pyrrolidone acetamide (Piracetam, 100 mg/kg) improves the secondary trace acquired during monocular pattern discrimination learning almost to the level of the primary trace, and facilitates the imperative IHT. Uncrossed optic projections and subcortical storage may contribute to IHT of brightness but not of pattern discrimination. It is concluded that IHT of visual engrams is mainly due to transcommissural encoding activated during learning or by transcommissural readout of lateralized traces.

Animals↗
PubMedDate not supplied

[Dopaminergic component in the mechanism of action of gamma-aminobutyric acid derivatives and structural analogs].

In experiments on rats and male mice the GABA derivatives fenibut, fepiron and the organosilicon compound N-methyl (3-trimethylsilil)pyrrolidone (IA) antagonized apomorphine sterotypy and aggressiveness. Fenibut and IA potentiated haloperidol catalepsy. Fenibut, fepiron, sodium hydroxybutyrate and IA also antagonized the effects of phenamine. The biochemical investigations have shown that fenibut and IA produce acceleration of the intraneuronal synthesis and catabolism of DA. It is suggested that the behavioral effects of the GABA derivatives are partly relative to inhibition of the dopamin--ergic system.

Amphetamine↗
PubMed1979

Simultaneous investigation of the cerebral circulation and cortical bioelectrical activity in dogs under the influence of piracetam.

By means of the methods of local cerebral rheoencephalography (REG) and electroencephalography (EEG) the effect of piracetam (1-acetamide-2-pyrrolidone, Pyramem) on cerebral circulation and brain bioelectrical activity was studied in acute experiments on dogs. The following REG parameters were assayed: anacrotic section of the curve and its relative part, amplitude and dicrotic index. The influence of the preparation on the spontaneous EEG was studied by means of surface electrodes, pH, pO2, and pCO2 were determined in blood samples from femoral artery and superior sagittal sinus and arterio-venous differences of O2 (AVD-O2) and CO2 (AVD-CO2) were calculated. The arterial pressure and ECG were followed continuously. The results showed that after piracetam administration (100 mg/kg i.v.) an improvement of the REG parameters is observed: increase of the amplitude and decrease of the values of the relative part and dicrotic index. The changes observed indicated cerebro-vascular resistance decrease and increase of the cerebral blood volume. The AVD-O2 increased and the negative AVD-CO2 decreased. The EEG data indicated an improvement in the functional state of the brain cortex. Suggestions as to mechanism of piracetam effect and the usefulness of the methods were made.

Animals↗
PubMed1981

5-Oxo-L-prolinase (L-pyroglutamate hydrolase). Studies of the chemical mechanism.

Rat kidney 5-oxo-L-prolinase catalyzes the endergonic hydrolysis of 5-oxo-L-proline (L-pyroglutamate, L-2-pyrrolidone-5-carboxylate) to form L-glutamate; the reaction is driven by and dependent on the stoichiometric concomitant hydrolysis of ATP to ADP and inorganic phosphate. The present studies are concerned with the mechanism by which the free energy of ATP hydrolysis is conserved and made available for 5-oxoproline hydrolysis. Studies with 18O-labeled substrates showed that (a) all three oxygen atoms of 5-oxoproline are recovered in the product glutamate, and (b) the two water molecules consumed in the reaction contribute one oxygen atom to inorganic phosphate and one oxygen atom to the gamma-carboxyl group of glutamate. It was shown that the enzyme also catalyzes the intrinsically exergonic hydrolysis of alpha-hydroxyglutarate lactone, a reaction that is ATP-dependent. Intermediates in the 5-oxoprolinase reaction were not detected by exchange experiments with radioactive ADP and phosphate, nor were they trapped by adding hydroxylamine. In the presence of very high glutamate concentrations, a slow reversal of the 5-oxoprolinase reaction was demonstrated by measuring ATP formation. The findings are consistent with a mechanism in which 5-oxo-L-proline is phosphorylated by ATP on the amide carbonyl oxygen and the resulting intermediate is subsequently hydrolyzed to yield gamma-glutamyl phosphate; the latter is hydrolyzed to glutamate and inorganic phosphate.

Adenosine Diphosphate↗
PubMed1984

[Effect on helper activity of synthetic polyelectrolytes introduced into an in vitro system of interacting macrophages and thymus cells].

Our experiments have shown that the joint incubation of thymocytes and syngeneic macrophages in vitro for 60 minutes is accompanied by a certain increase in the helper activity of thymocytes. The presence of polyacrylic acid or the copolymer of acrylic acid and N-vinyl-pyrrolidone, containing 56 mol% of acrylic acid, in this system ensures a considerable increase in the helper activity of thymocytes, incubated jointly with marrow cells and sheep red blood cells and then transferred into a cell culture in vivo.

Acrylic Resins↗
PubMedDate not supplied

Pharmacological inhibition of calmodulin-sensitive phosphodiesterases.

Two cyclic nucleotide phosphodiesterases sensitive to calmodulin were partially purified from bovine brain and bovine aorta. The enzyme from bovine brain exhibited the properties of the "high Km phosphodiesterase", with a higher Km for cyclic AMP than for cyclic GMP. The enzyme from bovine aorta hydrolyzed both cyclic AMP and cyclic GMP with similar kinetics. The hydrolysis of cyclic AMP by the brain enzyme was selectively inhibited by papaverine and 2' deoxy cyclic AMP. The hydrolysis of cyclic GMP by this enzyme was selectively inhibited by cyclic IMP, 2' deoxy cyclic GMP, 1-methyl-3-isobutyl-xanthine, ICI 74917 and M & B 22948. All these inhibitors were identically potent on the hydrolysis of both substrates by the aorta enzyme. Ro-20 1724, an imidazolidinone, and ZK 62711, a pyrrolidone, two compounds known to be potent inhibitors of cyclic AMP phosphodiesterase insensitive to calmodulin, were inefficient inhibitors of both calmodulin-sensitive phosphodiesterases.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Pharmacology and regional variations of quinolinic acid-evoked excitations in the rat central nervous system.

A physiological and pharmacological investigation of a novel endogenous excitant, quinolinic acid, was carried out in male rats using conventional iontophoretic techniques. It was established that quinolinic acid responses were preferentially reduced by antagonists acting at the N-methyl-D-aspartate (NMDA) preferring receptor, such as (+/-)-2-amino-7-phosphono-heptanoic acid and 1-hydroxy-3-amino-pyrrolidone-2. Glutamic acid diethyl ester reduced responses to quinolinic acid, quisqualic acid and NMDA with no clear specificity. Streptomycin, thought to act at the quisqualic acid receptor, largely spared quinolinic acid responses, being more effective against quisqualic acid evoked excitations. It is therefore suggested that quinolinic acid acts primarily at the NMDA receptor. In addition, the sensitivity of various components of the neuraxis to quinolinic acid was assessed and compared with glutamate and NMDA. Neurons in the spinal cord and cerebellum were largely unresponsive to quinolinate, whereas cells in the neocortex, striatum and hippocampus responded to this agonist to a similar degree as glutamate. In the cortex quinolinate was about one-fifth as active as NMDA, which together with quinolinic acid was much less active in the spinal cord and cerebellum. It is concluded that the possibility that quinolinic acid has a neurotransmitter type function at central "amino acid" receptors merits further investigation.

Animals↗
PubMedDate not supplied

[Neurochemical control of cerebral blood circulation].

A neurochemical approach to a study of the mechanisms by which cerebral circulation is controlled made it possible to discover the capability of GABA, GHBA, gamma-butyrolactone and pyrrolidone-2 to enhance cerebral circulation, to relax and enlarge an isolated flap of the cerebral arteries. GABA and specific GABA-receptors were found in the tissues of the walls of the cerebral arteries. Glutamate decarboxylase and GABA-transaminase were discovered in the cerebral vessels, with the endothelial and muscle layers of the arterial walls showing the highest GABA-transaminase activity. It is evident that as regards certain biochemical characteristics there is a definite similarity between GABA-ergic neurons and tissues of cerebral artery walls, which may ensure similar and undirectional neurochemical reactions in the brain and in the walls of its arteries. The latter circumstance is responsible for the mechanisms that control the functioning of the cerebral vessels.

4-Butyrolactone↗
PubMed1984

Stabilization and polysaccharide storage in group A Streptococcus pyogenes.

Water-shock treatment of group A Streptococcus pyogenes released a mixture of nucleotide-like substances and small amounts of protein. The amount of protein was much less than found with osmotic shock of Gram-negative bacteria. In group A S. pyogenes the osmolytes released exhibited as much as a 6-fold change in respect to different growth phases. Osmolyte release was dependent on the stabilization agent used and independent of cellular metabolic activity. The released osmolytes were found to be required for optimal intracellular iodophilic polysaccharide (IPS) storage. Stabilization of washing solutions, and IPS storage medium with metabolically inert non-ionic organic compounds prevented osmolyte loss and enhanced IPS storage. Polyvinyl pyrrolidone and polyethyleneglycol (MW greater than 1000) exhibited the same protective effects as found with calf serum. Smaller non-ionic organic compounds provided similar protective action but the bacteria were more susceptible to osmotic stress.

Maltose↗
PubMed1984

On the use of oxytetracycline in reducing the incidence of metritis in dairy cows.

50 dairy cows were alternately either given no perinatal treatment or were given an intramuscular injection of oxytetracycline in a 2-pyrrolidone base at a dosage rate of 20 mg/kg body mass. The incidence of metritis in the untreated (control) group was 46 out of 120 cows (38,3%), while in the treated group there were 30 metritis cows out of 130 (23%)--a statistically significant difference.

Animals↗
PubMed1977

Effects of carrageenan on immune responses. Studies on the macrophage dependency of various antigens after treatment with carrageenan.

Carrageenan, a sulfated polygalactose having macrophage toxic properties, elicited a marked suppression of IgM response to T cell-dependent antigens such as sheep red blood cells (SRBC), dinitrophenylated bovine serum gamma-globulin (DNP-BGG), and trinitrophenylated concanavalin A (TNP-Con A). In contrast, carrageenan did not inhibit antibody responses to such T cell-independent antigens as trinitrophenylated DEAE-dextran (TNP-DEAE-dextran), trinitrophenylated polyvinyl pyrrolidone(TNP-PVP), and trinitrophenylated Ficoll (TNP-Ficoll). Compared to total spleen cells, spleen cells from which macrophages had been removed by adhesion to plastic Petri dishes had less effect on the production of antibody against T cell-dependent antigens, but no change or a rather stimulated effect was observed in in vitro antibiody synthesis against T cell-independent antigens. These results strongly suggest that macrophages are involved in antibody responses to T cell-dependent antigens but not in those to T cell-independent antigens. However, the antibody response to trinitrophenylated lipopolysaccharide (TNP-LPS), a T cell-independent antigen, was inhibited by carrageenan treatment, suggesting that the response is macrophage dependent. Moreover, antibody response to higher doses of dinitrophenylated phytohemagglutinin (DNP-PHA), a T cell-dependent antigen, was shown to be macrophage independent by carrageenan treatment, although the antibody response to low doses of the antigen was macrophage dependent. Considering all these results, carrageenan treatment seems to be a very useful method to determine whether immune response to various antigens are macrophage dependent or not.

Animals↗
PubMed1983

Primary structure of human plasma fibronectin. The 29,000-dalton NH2-terminal domain.

The complete amino acid sequence of the NH2-terminal domain obtained after trypsin digestion of human plasma fibronectin has been determined. It contains residues 1-259 and has a Mr of 29,000. The 29-kDa fragment was isolated from the other major tryptic cleavage products of 200, 180, and 31 kDa by affinity chromatography on gelatin- and heparin-Sepharose columns. The two high Mr fragments bound to gelatin and were easily removed; the 31-kDa fragment failed to bind to heparin while the 29-kDa fragment did and was eluted with 0.15 M NaCl. The 29-kDa domain has a blocked NH2-terminal (pyrrolidone carboxylic acid) which was removed by digestion with pyroglutamate aminopeptidase, and the amino acid sequence of the first 36 residues was obtained. The sequence showed a glutamine residue at position 3 which is probably the acceptor site for transglutaminase as reported for bovine fibronectin. Extensive trypsin digestion of the completely reduced and alkylated 29-kDa fragment yielded twenty-four peptides which were separated and purified by high performance liquid chromatography; their amino acid composition and amino acid sequence has been determined and the arrangement of peptides was achieved by comparison with the sequence recently reported for bovine fibronectin. The sequences in human and bovine fibronectin were nearly identical with only nine amino acid differences which can all be explained by single base substitutions. Apparently this domain is highly conserved in the two species studied thus far.

Alkylation↗
PubMed1984

A simple experimental model for hydrophobic interactions in proteins.

The compound N-cyclohexyl-2-pyrrolidone contains a substantial apolar region as well as a peptide bond-like moiety. This solvent, therefore, provides a useful model for protein interiors. Under certain conditions of temperature and salt concentration, cyclohexylpyrrolidone forms a two-phase system with water. This permits partition coefficients and subsequent free energies of transfer of amino acid side chains from cyclohexylpyrrolidone to water to be simply determined. Free energies of transfer measured in this manner for 21 amino acids are found to be substantially less than those obtained from the commonly used ethanol/water solubility model. This suggests less of a contribution of hydrophobic interactions to the stabilization of protein structure than is conventionally assumed.

Amino Acids↗
PubMed1984

Clearance and organ localization of particles and soluble complexes in mice with circulating complexes.

The clearance and organ localization of a number of substances cleared by either Fc-dependent or -independent mechanisms was studied in normal mice and in mice with endogenously produced persistent circulating complexes. Clearance of covalent dimers of mouse IgG, chicken IgG and ovalbumin were no different between the two groups of mice. By contrast, hepatic and splenic uptake of dimeric mouse IgG (but not of chicken IgG or ovalbumin dimer) was impaired in the mice with persisting complexes. Surprisingly the rate of clearance of sheep red blood cells (SRBC) was increased in mice with persisting complexes as was hepatic uptake of polyvinyl pyrrolidone. It is suggested that the mononuclear phagocytes of mice with persistent circulating complexes are non-specifically stimulated while their ability to take up soluble complexes by Fc-dependent attachment is selectively impaired.

Animals↗
PubMed1983

A new opine derived from nopaline.

Nopaline (N-[4-[(aminoiminomethyl)amino-]-1S-carboxybutyl]-2R-aminopentanedioic acid and isonopaline (N-[4-[(aminoiminomethyl)amino-1S-carboxybutyl]- 2S-aminopentanedioic acid) have been synthesized and separated by crystallization. In addition, a derivative of each of these compounds that forms spontaneously from the parent compounds under the usual crystallization conditions was isolated and characterized. The chemical properties, elemental analysis, 1H-NMR spectrum, and electrophoretic behavior of the derivative from nopaline are consistent with N-[4-[ (aminoiminomethyl)amino]-1S-carboxybutyl]-2-pyrrolidone-5R-carboxylic acid, also called pyronopaline. The presence of pyronopaline in crown gall tumor tissue and the catabolism of it by the bacterium A. tumefaciens establish it as a new opine.

Arginine↗