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Biomedical subjects

V A Khramov

Publications and source records attributed to V A Khramov.

At least 19 recordsLinked to original sources
PubMed2005

[Oral fluid nitrate reductase complex activity in teenagers dependent on oral hygiene level and DMFT-index].

This research is directed to determine the influence of carious process at the stage of forming of constant occlusion on nitratereductase complex activity in the oral liquid. The correlation between of nitratereductase complex activity and DMF index, as well as the sex and the age of children with variable and constant occlusions was discovered. It is possible to estimate objectively a condition of a oral cavity due to nitratereductase complex activity.

Adolescent↗
PubMed2002

[Levels of amino group nitrogen and imidazole compounds in human oral fluid].

The procedures of definition amino nitrogen (sum amino acids) and imidazole compounds in human oral fluid are described. Amino nitrogen were determined by the ninhydrin method modified by the authors, imidazole compounds by the Pauli test. A total of over 20 patients with the relatively good dental status were surveyed. The level of amino nitrogen showed noticeable fluctuations (2.01 +/- 1.24 mmol per ml of oral fluid), whereas the content of imidazole derivatives was more stable (0.71 +/- 0.19 mmol/ml). Oral fluid samples displayed an in vitro high proteolytic activity, which explains contradictory results in the determination of the levels of amino nitrogen.

Amino Acids↗
PubMed2000

[A simple method of glucose measurement in human skin secretions].

A simple noninvasive procedure for measurements of glucose in skin secretion is described. The method is based on glucose oxidation reaction. Normal glucose content per cm2 is 1.9 +/- 0.9 nmol. A high correlation between blood glucose levels and skin excretion of glucose was detected in diabetics (r = 0.869).

Adult↗
PubMed1997

[A simple method of measuring ornithine decarboxylase activity in mixed human saliva].

A simple and sensitive method for measuring ornithine decarboxylase in mixed human saliva is described, based on assessing the waste of the reaction substrate ornithine by modified Chinard's color reaction. The highest specific activity of the enzyme (up to 1.5 ncat/ml) is found in salivary samples collected on an empty stomach in the morning. After centrifugation of the saliva the entire ornithine decarboxylase activity is localized in the mucin sediment.

Calorimetry↗
PubMed1997

[The utilization of amino acids and urea by human oral fluid].

Incubation of mixed human saliva with arginine, ornithine, and proline for 30 min to 2 h at 40 degrees C leads to an appreciable consumption of the above amino acids. The rate of utilization is 0.2 to 0.5 ncat/ml of saliva. The rate of urea loss is higher by an order of magnitude: up to 11 ncat/ml. Putrescin, urea (after incubation with arginine), and ammonium are identified as the products of these reactions. The biological significance of such reactions is believed to consist in neutralization of carbohydrate fermentation products. The detected consumption of amino acids and urea indicates that mixed human saliva contains urease, arginase, ornithine decarboxylase, and, probably, proline reductase. Since the origin of these enzymes is probably bacterial, changes in their activity in the saliva can be regarded as an indicator of dysbacteriosis and a diagnostically important parameter.

Amino Acids↗
PubMed1996

[The determination of the ureolytic and glycolytic activities of human oral fluid].

The authors describe a simple and rapid method for measuring urease and glycolytic activity of mixed saliva. It is based on alteration of the color of some acid-alkaline indicators during incubation of the saliva with appropriate substrata (carbohydrates and urea). Examinations of 32 normal subjects revealed that with the developed procedure, the reactions of carbohydrate fermentation and urea hydrolysis are rapidly detected in mixed saliva samples, the test taking approximately 20 min. Urea hydrolysis was accelerated in 62 patients with inflammatory processes in the periodontium, whereas the glycolytic processes were inhibited, this indicating an increase in the share of urease-positive microorganisms and depression of glycolytic flora. Hence, the described method for measuring urease and glycolytic activities of the oral fluid is recommended for clinical dentistry to be used for rapid diagnosis of oral diseases and for screening examination, as a simple, economic, easily reproducible, and noninvasive technique.

Glycolysis↗
PubMed1982

[Carbamoyl phosphate biosynthesis in Streptococci].

Nine streptococcal strains belonging to different serological groups (A, B, C, D) were shown to synthesize carbamoyl phosphate from ammonium hydrocarbonate and ATP. The reaction was catalyzed by carbamate kinase (EC 2.7.2.2). The speed of the reaction was evaluated according to the increase of the content of citrullin (the combination of carbamate kinase and ornithine transcarbamoylase). The representatives of different serological groups were found to have quantitative differences in carbamate kinase activity: the highest specific activity (13 nmol of citrullin per minute in 1 mg of dried microbial biomass) was detected in group A streptococci, while group D streptococci showed the lowest specific activity (0.5 nmol).

Carbamates↗
PubMed1980

[Correlation between the distribution and inhibition constants of bacterial agmatinase inhibitors].

A correlation between the distribution of chemical compounds in the water-non-polar solvent system and their inhibiting effect on bacterial agmatinase has been established. The correlation equation appears as lg(1/Ki)=algp0+C. The value of C is constant for homologous inhibitors but shows considerable variations upon a transition from the homologous row of alcohols to monoamines, diamines and guanidine alcanes. It is assumed that the value of C reflects the electrostatic interactions between the enzyme and ligand. Alternatively this value can be regarded as a factor of the ligand fitness into the enzyme active center. The correlation equations obtained for different homologous sequences allow to predict the inhibiting effect of still unknown homologues.

Alcohols↗
PubMed1979

[Interaction between dialkylamines and bacterial agmatinase].

It was demonstrated that aliphatic dialkylamines are more effective inhibitors of bacterial agmatinase than monoalkylamines and differ from the latter by the type of inhibition. The dependence of the inhibition constant on the hydrophobicity of the compounds tested was studied. The type of this dependence was found to be different for long- and short-radical dialkylamines, the correlation equation appearing as 1g(1/Ki) = 0,33 1gPo + (2,3 +/- 0,2) for the former compounds and as 1g(1/Ki) = 1,0 1gPo + (2,2 +/- 0,2) for the latter. The enzyme inhibition by the inhibitors tested was dependent on pH: e. g. with an increase in pH the inhibiting effect was decreased. It was assumed that the inhibitor sorption by agmatinase is of hydrophobic-ionic type and that the active site of the enzyme contains two hydrophobic zones separated by a nucleophylic group. The length of the hydrophoblic zones was estimated.

Agmatine↗
PubMed1978

[Effect of alcohols on the activity of bacterial agmatinase].

Aliphatic alcohols inhibit the activity of bacterial agmatinase (E. C. 3.5.3.11). A correlation is demonstrated between the inhibition constant and the length of alcohol carbohydrate radical, and the presence of polar groups has decreased the inhibitory effect. The importance of hydrophobic interactions in the formation of agmatinase-substrate and agmatinase-inhibitor complexes is suggested. The increment of free binding energy within the homologous alcohol row is practically constant (0.5-0.7 kcal/mole). Comparison of deltaF amines and their respective alcohols makes possible to evaluate the contribution of electrostatic interaction in the formation of the enzyme-inhibitor complex. A correlation is observed between solubility of alcohols and their inhibitory effect.

1-Propanol↗
PubMed1977

[Comparative study of bacterial agmatinase inhibition by derivatives of putrescine and aliphatic monoamines].

Aliphatic monoamines and some putrescine derivatives (10(-3) M) are found to inhibit agmatinase from Proteus vulgaris. Constants and the type of inhibition are determined. Investigation of the temperature effect on the inhibition has revealed an exotermic character of this process. Some thermodinamic parameters of agmatinase-anylamine binding reaction are calculated. 1-Guanidobutane is obtained by means of 1-amidobutane guanidilation, and it is found to be more efficient inhibitor than monoamines.

Agmatine↗