[Influence of changed gas media on acoustic parameters of human forced exhalation].

In previous study it was shown that duration of tracheal forced expiratory noises is promising to reveal negative changes of lung function after dive. The objective is a study of parameters of tracheal forced expiratory noises in changed gas media. The first experiment involved 25 volunteers (22-60 years), performed forced exhalation under normal pressure with air, oxygen-helium and oxygen-krypton mixtures. The second experiment in the chamber involved 6 volunteers (25-46 years), which performed forced exhalation with air under normal pressure (0.1 MPa), and under elevated pressure 0.263 MPa with air and oxygen-helium mixture. In the first experiment the direct linear dependence on gas density was found for forced expiratory noises common duration in the band of 200-2000 Hz and for its durations in narrow 200-Hz bands, excluding high frequency range 1400-2000 Hz. In the second experiment a significant reversed dependence of high frequency durations and spectral energies in 200-Hz bands (1600-2000 Hz) on adiabatic gas compressibility. Individual dynamics of common duration of tracheal forced expiratory noises under model dive of 16.3 m (0.263 MPa) is more then the diagnostic threshold of this parameter for lung function decrease, previously obtained for divers under normal pressure.

[Change in sensitivity of the central respiration mechanism in the 21-hour bedrest conditions].

The investigation was aimed at studying the mechanisms for change in the respiration center sensitivity in consequence of 21-hr bed rest with head-end tilted at -15 degrees combined with liquid loss (lasix, 20 ml) and recovery (IV infucol and glucose). Time of maximal breath-holding, capillary and venous O2 and CO2 pressure values were measured in the baseline data collection period, during and shortly after BR. Data analysis showed that extension of the maximal breath-holding time both during inspiration and expiration was statistically significant in the initial 10 minutes of tilting. Comparison of the breath-holding test data between the experimental series demonstrated that infusion of equally glucose and infucol did not affect voluntary apnea during inspiration or expiration. From BR hour 17, partial pressure of venous O2 showed a significant rise, while venous CO2 pressure decreased, also significantly. It is hypothesized that degradation of the respiration center sensitivity was connected most likely with blood pooling in the upper body and altered pressure on the baroreceptors.

[Characteristics of negative pressure inspiration effect on the cardiorespiratory system of humans in the conditions of 5-day dry immersion].

Changes in external respiration and central hemodynamics induced by negative (relative to atmospheric) inspiration pressure were studied in supine subjects before and on day-4 of a dry immersion (DI) experiment. Changes in the cardiorespiratory system as a result of negative inspiration pressure included rise of the amplitude of breathing motions and reduction of their frequency, and distinct breathing-related HR fluctuations. Combination of immersion and altered pressure in the mask caused breathing-related variations of systolic pressure and plethysmogram signal, and improved arterial blood oxygenation. These results can be useful for developing pressure-gradient methods of counteracting the adverse effects of blood redistribution toward the cranial-end.

[Biomechanics and regulation of the external respiration in the conditions of 5-day dry immersion].

The work was concerned with evaluation of the external respiration function and regulation in healthy human subjects participating in simulation of the microgravity effects by dry immersion (DI). In the baseline data collection period, in DI (days 2 and 4) and after DI completion pulmonary volumes were registered, the ratio of thoracic and abdominal components of quiet breathing and respiratory maneuvers calculated, and parameters of respiration regulation, i.e. length of breath-holding and ability to voluntary control breathing motions, were determined. It was shown that breathing pattern did not undergo gross changes in immersion as compared with pre-DI test data; however, inspiratory reserve volume grew (p < 0.05) and expiratory RV reduced (p < 0.01). DI did not alter the ventilation function of lungs; yet, most of the subjects trended to increase the abdominal component of quiet breathing and displayed a statistically significant increase of the parameter during the maneuver made to determine the vital capacity of lungs. Maximum breath-holding, equally in the course of inspiration and expiration in DI, did not differ from baseline values. Accuracy of voluntary breathing control was better in immersion. We believe that similar to microgravity, exposure in DI produces regular alterations of pulmonary RV (partly because of changed body position), thoracic-abdominal ratio in breathing motions, and shifts in voluntary respiration regulation.

[Immune system parameters of healthy humans in a chamber experiment with hyperbaric oxygen-nitrogen-argon air].

The investigation into the immune effects of 9-d exposure to elevated pressures of normoxic and hypoxic O2-N-Ar atmosphere showed changes in a number of indices of genetic and adaptive immunity in normal humans. Dynamics and depth of the functional shifts under the influence of the experimental factors appear to be connected with genetically coded mechanisms of immunoreactivity. Monitoring of immune homeostasis is basic to the prevention of immune adaptation failure.

[Metabolic and hormonal parameters of humans during long-term hyperbaric exposure (the recompression treatment table)].

Several metabolic and hormonal parameters were evaluated in blood of two human subjects during simulation of an extended saturation dive. Increases in creatine kinase and an upward trend in cholesterol and glucose were observed after decompression. The levels of TTH and thyroxin went up in both subjects during exposure. The significant changes in cortisol, ACTH, insulin and C-peptide were a fingerprint of stress-reaction. After eight days of recovery most of the parameters returned to baseline values. The investigation suggests that the recompression treatment table did not cause pathological changes in the biochemical and hormonal parameters of humans.

[Clinical-biochemical parameters of blood in humans exposed to the combined effects of short-term head-down tilt and isolation]. / Kliniko-biokhimiecheskie pokazateli krovi cheloveka pri sochetannom vliianii kratkovremennoi antiortostaticheskoi gipokinezii i izoliatsii.

Clinical biochemistry of blood was investigated in 6 human subjects during 7-d isolation in the head-down tilt position (HDT, -6 degrees), and in 2 subjects who also stayed in a pressurized module for 7 days but w/o motor restraint. The "dry chemistry" methods were employed to track shifts in carbohydrate, protein and lipid metabolism, plasma enzyme activity, and hemoglobin. Results of the discriminant analysis demonstrated a distinct effect after 3 d in HDT that was cancelled out by HDT day 6. Disperse analysis and Mann-Witney's Y-test revealed a considerable reduction in creatine phosphokinase and increase in triglycerides on HDT day 3. Low CPK activity was observed all the time during HDT. The control subjects displayed reduction in the aspartate aminotrasferase activity on day 3 in isolation. Clinical biochemistry of plasma remained generally within the clinical norm boundaries. All metabolic shifts were reversible and returned to baseline values after completion of the investigation. Hence, these data evidenced for functional nature of the shifts; isolation in the pressurized module did not aggravate the metabolic shifts due to adaptation to short-term HDT and ensuing readaptation.

[Substantiation of the use of pepsidil in secretory insufficiency of the digestive glands caused by antitubercular drugs]. / Obosnovanie ispol'zovaniia pepsidila pri sekretornoi nedostatochnosti pishchevaritel'nykh zhelez, vyzvannoi protivotuberkuleznymi preparatami.

The experiments on rats were undertaken to study the action of pepsidil to make up for the biosynthesis deficiency of digestive enzymes in the stomach and pancreas caused by antituberculous drugs (methazide + PAS, isoniazid + PAS, isoniazid + rifampicin + ethambutol). It was proved that pepsidil reduced an inhibiting action of antituberculous drugs on the activity of gastroenteric tract proteinases. The given condition should be taken into account when antituberculous treatment is conducted.

[Pepsin and trypsin proteolysis of the casein in cheeses of Soviet manufacture]. / Proteoliz kazeina syrov otechestvennogo proizvodstva pepsinom i tripsinom.

The content of protein and free amino acids in cheeses and susceptibility of casein from 11 samples of Soviet cheeses to gastrointestinal tract proteinases were studied. It was shown that the protein content in solid cheeses is higher than in processed and brine ones. The greatest number of free amino acids occurs in Poshekhonsky, Sovetsky and Sovetsky processed cheeses. Hydrolytic splitting of the cheese protein proceeds more vigorously under the effect of trypsin compared with pepsin. Therefore it is more desirable that trypsin be used for manufacture of enzymatic hydrolysates from casein. It is recommended that Gollandsky, Sovetsky, Litovsky and Poshekhonsky cheeses characterized by susceptibility to gastrointestinal tract proteinases be included into the diet of patients suffering from both secretory gastric and pancreatic exocrine function insufficiency.