[Method for determination of creatine in minced meat].

A rather version of picrate method for determination of creatine in minced meat is proposed. It is suitable for application in laboratories of meat-processing plants.

[Jaffe color test-based microtechnique for determination of milk lactose].

The picric acid reaction (Jaffe test) that is widely used in clinical biochemical practice to determine creatinine has proven to be suitable for the assay of lactose in milk samples. The reaction conditions (picric acid concentration, sample heating time, etc.) were examined to optimize this method. The specificity of this color test was also studied. Other reducing sugars, as well as glucose-6-phosphate and glycerol yielded a picric acid reaction. The level of lactose in the test milk samples (n = 14) ranged from 0.120 to 0.148 mmol/l.

[Urea as an indicator of anthropogenic pollution of water of swimming pools].

The sports swimming pools of Volgograd were examined for the levels of urea. All the study swimming pools were found to have a level of urea in the range of 28-80 micromol/l; which is about 10-15 times higher that its background level in the natural water reservoirs. Analysis of urea in the water of a swimming pool is proposed as a sensitive and simple test for fresh man-made water pollution.

[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.

[Levels of amino group nitrogen and imidazole compounds in human oral fluid]. / Uroven' aminoazota i imidazol'nykh soedinenii v rotovoi zhidkosti cheloveka.

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.

[A simple method of glucose measurement in human skin secretions]. / Prostoi sposob opredeleniia gliukozy v kozhnykh ékskretakh cheloveka.

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).

[A simple method of measuring ornithine decarboxylase activity in mixed human saliva]. / Prostoi metod opredeleniia aktivnosti ornitindekarboksilazy v smeshannoi sliune cheloveka.

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.

[The utilization of amino acids and urea by human oral fluid]. / Utilizatsiia aminokislot i mocheviny rotovoi zhikost'iu cheloveka.

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.

[Analysis of lactate, ammonia and urea in skin excretions]. / Analiz laktata, ammiaka i mocheviny v kozhnykh ékskretakh.

A procedure for measuring lactate, ammonium, and urea in a single 2 ml sample of aqueous wash-off from the palm of a man is described. In normal subjects the level of lactate excretion was 1.56 mmole/cm2 skin, that of ammonium 0.08 mmole, and of urea 0.1 mmole. This noninvasive method may be used in pediatrics, in examinations of athletes, etc.

[The determination of the ureolytic and glycolytic activities of human oral fluid]. / Opredelenie ureoliticheskoi i glikoliticheskoi aktivnosti rotovoi zhidkosti cheloveka.

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.

[Urea and ammonia in the saliva of patients with kidney diseases]. / Mochevina i ammiak v sliune bol'nykh pri zabolevaniiakh pochek.

Blood and salivary urea, salivary ammonia were measured in 39 patients: 11 with chronic renal failure stage I-II (group 1), 12 with chronic renal failure stage III (group 2), control subjects without renal diseases (control group of 16 patients). The findings indicated higher levels of salivary urea in group 1 and 2. Salivary and blood urea concentrations correlated, the proportions being 68%, 40.8% and 61% for group 1, 2 and controls, respectively. The treatment of group 1 and 2 patients resulted in parallel changes in blood and salivary urea. In group 2 salivary ammonia reached the amount 5.7 mmol/l against control values 3.0 +/- 0.5 mmol/l. Salivary urea levels reflect the progression of renal dysfunction and may serve a diagnostic criterium.

[The nitrate reductase activity of human saliva]. / Nitratreduktaznaia aktivnost' sliuny cheloveka.

Investigations of human saliva reductase activity report the enzyme inactivation in 5-min heating at 50 degrees C, its maximal activity in neutral medium, reduced specific activity in the saliva dilution. Routine centrifugation inactivated nitrate reductase in supernatant, its activity in the precipitate hardly reached 10%. Combination of supernatant with precipitate recovered the baseline activity completely. Nitrates reduction into nitrites requires donor electrons. The latter are suggested to be present in the supernatant. Dehydrogenases substrates (lactate, pyruvate, malate, etc.) may act as donor electrons for nitrate reductase reaction. The addition of lithium lactate instead of supernatant to the precipitate partially recovered nitrate reductase activity. Biological role of salivary nitrate reductase is considered.

[Various properties of urease encapsulated into liposomes]. / Nekotorye svoistva ureazy, inkapsulirovannoi v liposomy.

The enzymic activity of plant urease encapsulated into liposomes from egg lecithin was studied. Liposomes contained 3-5% of the initial enzymic preparation. Incorporation of urease into liposomes increases the permeability of the lecithin membrane for urea. The liposome membrane provides protection of the incorporated material from the inhibitory action of heavy metal ions. Kinetics of the reactions catalyzed by the free enzyme and encapsulated one is different. Km for the encapsulated enzyme is 1 X 10(-3) M and for free urease--4 X 10(-4) M, that is related to limited substrate mass transfer rate and as a result of it due to inhomogeneity of the catalysis proceeding in liposomes.