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At least 739 records · Page 41Linked to original sources
PubMedDate not supplied

Metabolism of dibasic esters by rat nasal mucosal carboxylesterase.

Inhalation exposure of rats to dibasic esters revealed lesions of the nasal olfactory epithelium similar to those observed with other ester solvents. Female rats are more sensitive to these effects than are male rats. It has been proposed that carboxylesterase conversion of inhaled esters within nasal tissues to organic acids may be a critical biochemical step in converting these chemicals to toxic substances. These experiments measured the kinetic parameters Vmax, KM, Ksi, and V/K for the hydrolysis of the dibasic esters in the target nasal tissue, olfactory mucosa, and nontarget tissue, respiratory mucosa. It was determined that under the conditions of these experiments, diacid metabolites are not formed. Esterase activity was inhibited by pretreatment with bis p-nitrophenyl phosphate. Vmax values for the three dibasic esters were 5- to 13-fold greater in olfactory mucosa than respiratory mucosa for male or female rats. V/K values were 4- to 11-fold greater in olfactory mucosa than respiratory mucosa for male or female rats. V/K was similar between male and female olfactory mucosa when dimethyl glutarate was used as the substrate. With dimethyl succinate or dimethyl adipate as the substrate, V/K for female olfactory tissue was 0.5- or 2-fold that of males, respectively. Differences in V/K were mainly due to decreases in KM associated with increasing carbon chain length. Substrate inhibition was observed at dibasic ester concentrations greater than approximately 25 mM, which are unlikely to be achieved in vivo. These results lend further support to the hypothesis that organic acid accumulation in the target tissue, olfactory mucosa, plays a significant role in the pathogenesis of dibasic ester-induced nasal lesions. This mechanism may be applicable to a wide range of inhaled esters.

Adipates↗
PubMedDate not supplied

[Mechanical lysis of human erythrocytes. Membrane stabilization by plasma proteins].

Mechanical properties of erythrocyte membranes play an important role in red cell functions. Stability of human erythrocytes under deforming mechanical tensions which occur in the rapidly moving fluid is studied. The activation energy of the mechanical hemolysis determined by the temperature dependence of the hemolysis rate is 55 + 7 kJ/mol. The fragility of erythrocytes rises sharply as the salt concentrations increase. Glutaric dialdehyde forms a certain number of interprotein bonds which increase the fragility of erythrocytes. The mechanical stability of the erythrocyte membrane falls at high (0.5 M) ethanol concentrations. Blood plasma proteins, particularly human serum albumin, have a pronounced stabilizing effect. The hemolysis occurring during the rapid mixing is not probably associated with an osmotic mechanism since high sucrose concentrations do not prevent this process. The mechanical hemolysis depends both on the deforming tension arising in the membrane and on the state of the erythrocyte membrane.

Biomechanical Phenomena↗
PubMed1991

[Inborn errors of lysine metabolism].

A wide variety of inborn errors of lysine catabolism have been described. They include: abnormalities of the mitochrondrial catabolism via the "saccharopine pathway", abnormalities of the peroxisomal catabolism via the pipecolic pathway, and "lysine intolerance with periodic ammonia intoxication" linked to urea cycle pathway. These inborn errors are associated with a wide variety of clinical symptoms and biochemical profiles as persistent hyperlysinemia, saccharopinuria, "amino and ketoadipic aciduria, and glutaric aciduria.

2-Aminoadipic Acid↗
PubMedDate not supplied

[Study of oligohemoglobin solutions in vitro and in vivo].

Solutions of oligohemoglobins (OHb) with middle molecular mass 100 x 10(3) = 400 x 10(3), obtained after polycondensation of hemoglobin with glutaric aldehyde as well as oligohemoglobin modified with pyridoxal-5-phosphate, were studied in vivo and in vitro (plethoric administration, isovolemic metabolic substitution, hemorrhagic shock; at a dose of 0.5-1.8 g/kg of body mass; dogs, rabbits, rats). With increase of the OHb molecular mass period of its circulation in blood was elevated; blood plasma protected OHb from autooxidation; half-life of OHb was about 12-18 hrs in isovolemic metabolic substitution and in hemorrhagic shock and about 5 hrs--in plethoric administration. During circulation molecular mass selection of OHb occurred, where low molecular fraction decreased and high molecular fraction--accumulated; sign and value of human erythrocyte charge were similar both in OHb solutions with concentration up to 5% and in physiological solution.

Animals↗
PubMed1990

[The evaluation of the size variations in alginate subjected to the sterilizing action of glutaraldehyde].

The work takes into consideration the changes of dimension undergone by alginate submitted to the sterilizing action of aldehyde glutarate, after the impression. Trough the use of computerized analyser of images, samples of sterilized alginate have been compared with control samples. The results obtained can give a useful contribution to the prophylaxis of the crossed transmission of infection in the dental field.

Alginates↗
PubMed1990

Development of urease-chitosan membrane.

Urease was covalently immobilized on glutaraldehyde-pretreated chitosan membrane. The optimum immobilization conditions were determined with respect to glutaraldehyde pretreatment of membranes (concentration and pH of glutaraldehyde solution, time of membrane-glutaral-dehyde reaction) and to reaction of glutaraldehyde-pretreated membranes with urease (concentration and pH of urease solution). The obtained membrane has high enzymatic activity, and can be applied for enzymatic removal of urea e.g. in the treatment of chronic or acute uraemia.

Animals↗
PubMed1989

Inhibition of sorbitol formation in human erythrocytes by calcium dobesilate.

The effects of calcium dobesilate (Doxium, a drug already known to prevent or reverse the retinal microvascular lesions of diabetes mellitus) on sorbitol formation in human erythrocytes was studied, and compared with the effects of tetramethylene glutaric acid (TMGA), a specific aldose reductase inhibitor. Both compounds inhibited sorbitol formation. In a 29 mmol/l glucose medium, calcium dobesilate in concentrations of 2 and 10 mmol/l caused, 50 and 100% inhibition of sorbitol formation, respectively, whereas TMGA completely inhibited sorbitol formation at a concentration of 0.1 mmol/l. These results suggest that calcium dobesilate may exert, at least in part, its beneficial effect on diabetic microangiopathy by inhibiting the formation of sorbitol. The inhibition of sorbitol synthesis may be mediated by an inhibitory action of calcium dobesilate on aldose reductase.

Aldehyde Reductase↗
PubMed1989

[The role of phosphorylase kinase subunits in interaction with glycogen].

The interaction of rabbit skeletal muscle phosphorylase kinase with CNBr-activated glycogen results in the formation of a covalent complex. The non-bound kinase was removed by chromatography on DEAE-cellulose and phenyl-Sepharose. The amount of the bound protein increased with an increase in the number of activated groups in the glycogen molecule; the enzyme activity was thereby decreased. The kinase covalently and non-covalently bound to glycogen exhibited a higher affinity for the protein substrate (phosphorylase b) as well as for Mg2+ and Ca2+ than did the kinase in the absence of glycogen. Electrophoresis performed under denaturating conditions showed that the gamma-subunit of phosphorylase kinase is responsible for the enzyme binding to CNBr-glycogen. The effect of cross-linking reagents (glutaric aldehyde, 1.5-difluoro-2.4-dinitrobenzene) on the binding of phosphorylase kinase subunits was studied. Glycogen afforded protection of the gamma-subunit from the cross-linking to other enzyme subunits. An analysis of the subunit composition of phosphorylase kinase covalently bound to CNBr-glycogen and of the enzyme treated with cross-linking reagents in the presence of glycogen-revealed that the gamma-subunit is involved in the specific binding of phosphorylase kinase to glycogen.

Animals↗
PubMed1989

[Transport of monosaccharides in model systems: inhibition of sugar transport in frog muscle fibers, treated with glutaraldehyde].

The entry of D-xylose, a permeable non-metabolizing glucose analog, in the frog muscle fibers was examined. The sugar transport system activity was established in the frog muscle fibers treated by 0.3% glutaraldehyde. The basal transport as well as insulin activated D-xylose transport was seen preserved. Sugar transport inhibitors, phlorizin, phloretin and cytochalasine B reduce the rate of D-xylose transport in this "glutar model" of a muscle fiber. A long treatment by glutaraldehyde (3.5 hours at 4 degrees C, and 1 hour at 20 degrees C) leads to a 40% decline in the entry rate of D-xylose.

Aldehydes↗
PubMed1989

The distribution of aldose reductase and aldehyde reductase II in different regions of bovine lens.

The distribution of aldose reductase and aldehyde reductase II in the epithelium, cortex and nuclear regions of the bovine lens has been studied. The levels of the two enzymes in different regions of the bovine lens were determined after partial purification by DEAE-cellulose (DE-52) column chromatography. Aldose reductase was present in all the three regions of the lens, whereas aldehyde reductase II was present mainly in the epithelium and cortex. The activity of the enzymes, expressed per mg protein, was 10-15 fold higher in lens epithelium as compared to cortex and when expressed per g tissue wet weight, was approximately 2 fold higher. Substrate specificity of aldose reductase purified from all three regions of the lens was comparable, but the susceptibility to inhibition by various aldose reductase inhibitors was significantly different. As compared to the enzyme of cortex and nucleus, the epithelial aldose reductase was less (30-40%) susceptible to inhibition by aldose reductase inhibitors such as sorbinil, tolrestat, statil and tetramethylene glutaric acid. The substrate specificity and characteristics of inhibition of aldehyde reductase II purified from epithelium and cortex were similar.

Alcohol Dehydrogenase↗
PubMed1985

Use of proton nuclear magnetic resonance spectroscopy in detection and study of organic acidurias.

We used high-resolution proton nuclear magnetic resonance spectroscopy to detect, identify, and study the major normal and abnormal organic acid metabolites in urine from patients with propionic acidemia, methylmalonic aciduria, branched-chain ketoaciduria, isovaleric acidemia, and glutaric aciduria type I. Characteristic and diagnostic spectra were obtained at 400 MHz for each disorder in all the patients studied and neutral and basic compounds, including amino acids and acylcarnitines, were also detected. The technique is rapid (10 min) and requires small samples (0.5 mL) and no preliminary extraction or derivative preparation. We believe that it is particularly suitable for the rapid and acute diagnosis of inborn errors of metabolism, especially the organic acidurias, and for acute pediatric clinical care, when rapid monitoring of major metabolic alterations is required in a time scale suitable to influence directly and immediately the therapy of the patients concerned.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

[Modification of the radiosensitivity of bacteria by glutaraldehyde].

A study was made of the combined effect of ionizing radiation and various concentrations of glutaric aldehyde (0.00125, 0.0025, 0.5, and 1 per cent) on viability of bacteria differing in a cell wall structure, radiosensitivity, and activity of DNA repair system. The combined effect of the two factors was shown to produce an effect of superadditive enhancement of bacterial cell death. The synergism was more pronounced in highly radiosensitive bacteria.

Aldehydes↗
PubMed1980

[Oligomerization of integral membrane proteins under lipid peroxidation].

Using polyacrylamide gel electrophoresis in the presence of Na-SDS, the oligomerization of membrane proteins of the retinal rod outer segments of the frog and the wall-eyed pollock and of rabbit skeletal muscle sarcoplasmic reticulum was studied. It was shown that under storage of the retinal rod outer segments the rhodopsin oligomerization is inhibited by the lipid peroxidation inhibitor--ionol. Similar oligomerization was observed under induction of lipid peroxidation in the membranes; the accumulation of the lipid peroxidation product--malonic dialdehyde--was accompanied by disappearance of the rhodopsin monomeric form in the outer segments. The cross-linking agent--glutaric dialdehyde--also causes oligomerization of the rhodopsins. Similar aggregation is also characteristic of the major protein of the sarcoplasmic reticulum fragments, i. e. Ca2+-dependent ATP-ase. Thus, one of the main changes in the protein content of biomembranes under lipid peroxidation is the oligomerization of integral proteins due to their interaction with bifunctional reagents, i. e. lipid peroxidation products.

Animals↗
PubMed1995

[Effect of electrostatic interactions on formation and properties of soluble heteroprotein conjugates based on proteolytic enzymes].

The regularities of directed polycondensation of proteins with opposite charges by glutaric aldehyde were studied using serum albumin and proteolytic enzymes (urokinase, trypsin, alpha-chymotrypsin) as models. The electrostatic interaction of oppositely charged protein macromonomers in the polycondensation process was shown to facilitate the selective synthesis of soluble heteroprotein conjugates with molecular mass from 2 x 10(5) to 9 x 10(5); these conjugates have controlled component composition, high enzyme content (up to 3 to 4 molecules of an enzyme per one albumin molecule) and completely retain the enzyme catalytic activity. The dependence of rate constants and activation parameters of thermal inactivation of the heteroconjugates upon their composition, molecular mass and the degree of modification of the protein amino groups was investigated. Heteroconjugates of electrically asymmetric proteins, in particular, trypsin and serum albumin, were found to be several hundred times more stable than the starting enzymes at 38-60 degrees C.

Catalysis↗
PubMed1976

[Indirect hemagglutination via glutaraldehyde-treated erythrocytes for determining anti-anthrax antibodies].

The so-called passive hemagglutination reaction is used in this country to determine the serum level of anthrax antibodies in immunized individuals. Use is made of an erythrocyte diagnostic means prepared from formalin- and tannin-treated sheep erythrocytes that have been sensibilized with a protective anthrax antigen. An attempt has been made to replace this means by another one obtained by treating the same erythrocytes with glutaric aldehyde. Comparative studies reveal that the new diagnostic means is equally effective in the passive hemaglutination reaction as is the classic method using formalin- and tannin-treated erythrocytes. The suggested method of erythrocyte treatment proves more feasible, and, according to preliminary data, the new diagnostic means has longer shelf-life.

Aldehydes↗
PubMed1977

Substrate specificity of succinyl-CoA transferase from rat kidney mitochondria.

1. Succinyl-CoA: 3-oxoacid transferase (EC 2.8.3.5) from rat kidney mitochondria, purified about 200-fold, catalyses the CoA transfer from acetoacetyl-CoA to succinate, acetoacetate, maleate, glutarate and malonate; maleate proved to be a true substrate of the enzyme. 2. Double-reciprocal plots of the initial reaction rates against substrates concentrations arb best fitted by parallel lines. Inhibition by each acid product of the reaction is competitive with respect to the acid acceptor of CoA. 3. CoA-transferase from rat kidney shows similar kinetics as, but different substrate specificity than, the enzyme from other sources.

Acetoacetates↗
PubMed1995

Evaluation of dimensional stability of elastomeric impression materials during disinfection.

Disinfection of impression materials is recommended for preventing cross-contamination in dental clinics. However, aspects of the evaluation of elastomeric impression materials only slightly subjected to the effects of disinfectants have not been established. Therefore, the effects of sodium hypochlorite, glutaral, iodine, and ethanol disinfectants on elastomeric impression materials, condensation silicone, polysulfide, addition-type silicone (vinyl silicone), hydrophilic vinyl silicone, and polyether, were evaluated directly in a time-dependent manner by a non-contact displacement meter. Condensation silicone impression materials and polysulfide rubber impression materials greatly shrank over time, but their shrinkage decreased with immersion in disinfectants. Vinyl silicone impression materials and polyether impression materials showed excellent dimensional stability in air. However, hydrophilic vinyl silicone impression materials and polyether impression materials expanded greatly when immersed in disinfectants, especially when immersed in ethanol. Hydrophobic vinyl silicone impression materials showed excellent dimensional stability regardless of the presence or absence of disinfectants.

Dental Impression Materials↗
PubMedDate not supplied

[Acid-induced hemolysis of human erythrocytes].

The acid-induced haemolysis of human erythrocytes has been studied in the isoosmotic media (0.14 M NaCl) at pH 2.0-3.5. The apparent rate constant of this process increased and the time of lysis of half of the cells decreased after spectrin denaturation in the presence of ethanol. The time of the haemolysis diminished in the presence of human serum albumin, which interacted with the cell surface, and after erythrocyte modification by glutaric aldehyde. On the contrary, the hyperosmotic contraction of erythrocytes in the NaCl, KCl, or sucrose containing medium stabilized the cells. The activation energy of the process of acid-induced haemolysis determined by the temperature dependence of the haemolysis time was 69 +/- 4 kJ/mol. The cell volume increasing which induced by proton increasing, occurred at higher pH values (pH 5.5-5.0) as compared with pH inducing cell lysis. We suggest that not only osmotic mechanism takes part in the acid-induced haemolysis.

Cell Size↗