Effects of various hyperbaric gas mixtures on metabolic parameters of human blood

Changes in metabolic parameters of healthy subjects were studied during experimental 4-to 21-day courses of simulated diving in hyperbaric normoxic (oxygen-helium), hyperoxic (oxygen-nitrogen-helium), and argon-containing gas mixtures with different oxygen contents. The blood concentrations of primary substrates and activity of enzymes were measured spectrophotometrically. In most cases, the clinical and biochemical parameters of the blood remained within normal clinical ranges and exhibited significant individual variations. Long-term simulated deep dives (>200 m) resulted in changes in lipid metabolism expressed as an increase in the plasma concentrations of triglycerides, low-density lipoproteins, and polyunsaturated fatty acids. No significant changes were found during experimental 70-m dives performed according to recompression treatment table with the use of a hyperoxic helium-containing gas mixture. In contrast, long-term exposure to a normoxic argon-containing mixture at a pressure of 5 msw caused a significant increase in the blood contents of triglycerides, total cholesterol, and glucose, as well as a smaller increase in the activities of several tissue enzymes. At the same pressure, hypoxic oxygen-nitrogen-argon and oxygen-nitrogen mixtures did not affect the majority of clinical and biochemical parameters examined. However, in some subjects, they increased the atherogenicity index, concentrations of triglycerides, and activities of lactate dehydrogenase and alkaline phosphatase. The absence of any pathological changes in clinical and biochemical parameters of the blood indicates that both gas mixtures are safe and can be used in barochambers. Episodic changes in lipid metabolism and enzyme activities observed in healthy subjects exposed to helium-and argon-containing gas mixtures can be interpreted as a reversible hepatic dysfunction due to the high pressure. The extent of the changes in the parameters of lipid metabolism in the blood is determined by the magnitude of the overpressure and the duration of the exposure.     

Influence of modified gas mixtures on the acoustic parameters of human forced exhalation

It was earlier demonstrated that the duration of tracheal noises of forced exhalation (FE) looks to be promising to determine adverse changes in the lung function after a dive. This study dealt with the parameters of tracheal expiratory noises (FE) as dependent of the composition of breathing gas mixtures. In the first type of experiments, 25 volunteers aged from 22 to 60 years carried out forced exhalation under a normal pressure of air or of an oxygen-helium or oxygen-krypton mixture. In the second type of experiments, six volunteers from 25 to 46 years of age performed forced exhalation with air in an altitude chamber under a normal pressure (0.1 MPa); the same subjects performed FE under an elevated pressure (0.263 MPa) while breathing air or an oxygen-helium mixture. In the first type of experiments, the total duration of tracheal FE noises in the frequency range 200?C2000 Hz and 200-Hz bands FE noises depended directly and linearly on the density of the gas mixture; this was not the case in the high-frequency band from 1400 to 2000 Hz. In the second type of experiments, the high-frequency durations and spectral energies of tracheal FE noises (1600?C2000 Hz) depended inversely and significantly on the adiabatic gas compressibility. In a simulated dive to a depth of 16.3 m (0.263 MPa), individual changes in the total duration of tracheal FE noises exceeded the diagnostic threshold of deterioration of the lung function in divers that was determined earlier under normal pressure.     

Postprandial transformations of enzymatic and hormonal properties of saliva and blood

In 14 volunteers, saliva from both parotid, submandibular and sublingual glands were collected by capsules under stimulation of sialosis with citric acid or alimentary trial breakfast. It was taken immediately and on the 1st and 3rd hours of postprandial response. In saliva and the blood serum, alpha-amylases, trypsin, common protein, thyrotropin, thyroxine, triiodthyronin, luteinizing hormone, follicle-stimulating hormone, prolactin, progesterone, oestradiol and hydrocortisone were assessed by means of immuno-assay technique. All but oestradiol hormones had a lower concentration in the saliva than in the blood serum. The concentration and deficits of hormones and trypsin in saliva of submandibular and sublingual glands is higher, than in saliva of parotid glands, the latter having a higher alpha-amylolytic activity. The share of p-amylase in comparison with s-amylase in saliva of parotid glands is lesser than in saliva of submandibular and sublingual glands. In alimentary stimulation of sialosis, the saliva with higher amylolytic and tryptic activity, higher concentration of thyrotropin and thyroxine was found than under a non-alimentary stimulation. After the 1st and the 3rd hours following a trial breakfast, in response to a non-alimentary stimulation of sialosis the saliva was found to preserve properties of a postprandial saliva.     

Protein content of human saliva in various psycho-emotional states

The protein composition of human saliva depends on psycho-emotional state of individuals. Depression was accompanied by decrease of proteins of molecular masses ranging from 20 to 200 kD, whereas emotionally positive intellectual activity caused the opposite effect. It is suggested that human saliva may be used as an experimental model for the development of diagnostics of various psycho-physiological states.     

Hemodynamic and hormonal effects of human ghrelin in healthy volunteers

To investigate hemodynamic and hormonal effects of ghrelin, a novel growth hormone (GH)-releasing peptide, we gave six healthy men an intravenous bolus of human ghrelin (10 microg/kg) or placebo and vice versa 1-2 wk apart in a randomized fashion. Ghrelin elicited a marked increase in circulating GH (15-fold). The elevation of GH lasted longer than 60 min after the bolus injection. Injection of ghrelin significantly decreased mean arterial pressure (-12 mmHg, P < 0.05) without a significant change in heart rate (-4 beats/min, P = 0.39). Ghrelin significantly increased cardiac index (+16%, P < 0.05) and stroke volume index (+22%, P < 0.05). We also examined ghrelin receptor [GH secretagogues receptor (GHS-R)] gene expression in the aortas, the left ventricles, and the left atria of rats by RT-PCR. GHS-R mRNA was detectable in the rat aortas, left ventricles, and left atria, suggesting that ghrelin may cause cardiovascular effects through GH-independent mechanisms. In summary, human ghrelin elicited a potent, long-lasting GH release and had beneficial hemodynamic effects via reducing cardiac afterload and increasing cardiac output without an increase in heart rate.     

Effects of dietary manipulations on blood glucose and hormonal responses following supramaximal exercise

The effects of supramaximal exercise on blood glucose, insulin, and catecholamine responses were examined in 7 healthy male physical education students (mean +/- SD: age = 21 +/- 1.2 years; VO2max = 54 +/- 6 ml X kg-1 X min-1) in response to the following three dietary conditions: a normal mixed diet (N); a 24-h low carbohydrate (CHO) diet intended to reduce liver glycogen content (D1); and a 24-h low CHO diet preceded by a leg muscle CHO overloading protocol intended to reduce hepatic glycogen content with increased muscle glycogen store (D2). Exercise was performed on a bicycle ergometer at an exercise intensity of 130% VO2max for 90 s. Irrespective of the dietary manipulation, supramaximal exercise was associated with a similar significant (p less than 0.01) increase in the exercise and recovery plasma glucose values. The increase in blood glucose levels was accompanied by a similar increase in insulin concentrations in all three groups despite lower resting insulin levels in conditions D1 and D2. Lactate concentrations were higher during the early phase of the recovery period in the D2 as compared to the N condition. At cessation of exercise, epinephrine and norepinephrine were greatly elevated in all three conditions. These results indicate that the increase in plasma glucose and insulin associated with very high intensity exercise, persists in spite of dietary manipulations intended to reduce liver glycogen content or increase muscle glycogen store.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of a radiofrequency electromagnetic field on cardiovascular and hormonal parameters of the autonomic nervous system in healthy individuals

The potential health risks of radiofrequency electromagnetic fields (EMFs) emitted by mobile phones are of considerable public interest. The present study investigated the hypothesis, based on the results of our previous study, that exposure to EMFs can increase sympathetic vasoconstrictor activity. Forty healthy young males and females underwent a single-blind, placebo-controlled protocol once on each of two different days. Each investigation included successive periods of placebo and EMF exposure, given in a randomized order. The exposure was implemented by a GSM-like signal (900 MHz, pulsed with 217 Hz, 2 W) using a mobile phone mounted on the right-hand side of the head in a typical telephoning position. Each period of placebo exposure and of EMF exposure consisted of 20 min of supine rest, 10 min of 70 degrees upright tilt on a tilt table, and another 20 min of supine rest. Blood pressure, heart rate and cutaneous capillary perfusion were measured continuously. In addition, serum levels of norepinephrine, epinephrine, cortisol and endothelin were analyzed in venous blood samples taken every 10 min. Similar to the previous study, systolic and diastolic blood pressure each showed slow, continuous, statistically significant increases of about 5 mmHg during the course of the protocol. All other parameters either decreased in parallel or remained constant. However, analysis of variance showed that the changes in blood pressure and in all other parameters were independent of the EMF exposure. These findings do not support the assumption of a nonthermal influence of EMFs emitted by mobile phones on the cardiovascular autonomic nervous system in healthy humans.     

Patterns and variability in electrophoretic polypeptide profiles of human saliva in a healthy population

Electrophoretic polypeptide profiles of normal human saliva differ markedly between different reports. Since both methodological variations and polymorphism may explain these differences, in this study we aimed to establish whether or not the salivary electrophoretic polypeptide profiles of subjects from a healthy population share discrete molecular features. To this end, parotid, submandibular/sublingual and whole salivas were collected separately from each of 40 young and 34 elderly clinically healthy adults and processed for SDS-polyacrylamide gel electrophoresis and Coomassie blue staining. Each type of glandular saliva displayed a different group of invariant (i.e. present in every subject) electrophoretic polypeptide bands while whole saliva showed a profile that reflected mostly the combined contribution of the major salivary glands. Some minor variant (i.e. absent in some subjects) bands were identified in each type of saliva. Regarding those interindividual variations, no age- or sex-dependence was appreciated. Altogether, these results demonstrate the occurrence of distinctive electrophoretic polypeptide patterns, in addition to some minor variations, for each type of normal saliva, thus providing a background for further populational studies on salivary polypeptide profiles.