[The dipeptide L-alanyl-L-glutamine--its preparation and therapeutic use]. / Dipeptid L-alanyl-L-glutamin--jeho príprava a terapeutické vyuzití.

L-glutamine, representing one of the principal sources of nitrogen for the organism, can be used in infusion solutions employed in clinical nutrition in the form of the dipeptide L-alanyl-L-glutamine. It can be prepared with the use of biotechnological methods, viz. the enzymic synthesis of the peptide, and fermentation preparation of L-glutamine and the proteases catalyzing the formation of the peptidic bond. Suitable producers of amino acids and enzymes are microorganisms (both bacteria and fungi). The procedures used in the preparation of the components as well as the dipeptide itself are a combination of biotransformations and fermentations.

[The importance of catecholamine determination in athletes]. / Význam stanovení katecholaminu u sportovcu.

During a physical as well as mental load as a rule sympathoadrenal activation occurs which leads to a rise of catecholamine plasma levels and their increased excretion. The author investigated changes of plasma catecholamines and their urinary excretion during different experimental conditions in the laboratory and in field work. These changes were assessed after different loads in trained and not trained subjects and the effect of different types of stress was investigated. As to stressing stimuli, the authors reports in the present work on the effect of hypoxia, dehydration, psychological stress, anticipation stress and the combined effect of stress and biorythms.

The metabolic effects of acute and chronic administration of gastrozepin.

The structure of gastrozepin (G) resembles that of tricyclic antidepressants and antihistaminic and antiserotonic cyproheptadine which are compounds with known metabolic effects. The object of this study was to test the potential action of G on the metabolism of basic nutrients, insulin and selected hormonal parameters after parenteral administration (10 and 20 mg G) and after chronic oral administration (50 mg G) during antiulcer therapy. Investigations carried out in two groups of 7 and 9 healthy volunteers, respectively, and on one group of seven patients with ulcer disease, revealed no changes in any of the blood parameters studied, nor in the excretion of catecholamines or 17-OH steroids in the urine. Our observations practically rule out any metabotropic activity of G, thereby differentiating it from tricyclic antidepressants and cyproheptadine. Isolated significant differences from the basal value seen after G and saline, can be attributed to other than pharmacological or specific mechanisms such as stress associated with the first examination, effect of fasting, individual response of the subjects, and so on.

Circadian rhythms of urinary sodium, potassium and some agents influencing their excretion in young borderline hypertensives.

The circadian rhythms of sodium (Na+), potassium (K+), aldosterone (ALDO), 11-deoxycorticosterone (DOC), 18-hydroxy-DOC (18-OH-DOC), cortisol (F), corticosterone (B), adrenaline (A), noradrenaline (NA), dopamine (DA), metanephrine (MN), normetanephrine (NMN), homovanillic acid (HVA), kallikrein (KE) and prostaglandins E (PGE) and F2 alpha (PGF2 alpha) excretion were studied in eight young borderline hypertensive men (BHT) and in six healthy age-matched normotensive subjects (NT) during hospitalization, after adaptation to the hospital regimen and a diet containing 135 mmol Na+ and 90 nmol K+. Urine samples were collected in 4 h periods for 24 h: 1. at normal daily activity, 2. during a 24 h bed rest. The results were evaluated by means of cosinor analysis. The circadian rhythms of ALDO, F, B, 18-OH-DOC and PGF2 alpha excretion were similar in both groups, with the exception of higher mesors of urinary ACTH-dependent corticosteroids in BHT at normal daily activity. Differences were observed in the rhythms of Na+, A, NA, DA, HVA and PGE excretion, this, however, above all during the normal daily regimen. The curve of urinary Na+ was flat in BHT due to a higher portion of Na+ excreted during the night. In the rhythms of A, NA and PGE excretion, the acrophases were shifted to the later hours in BHT, and the mesors of A and NA were also significantly higher. In contrast, DA and HVA excretion curves were flat with a lower mesor. These changes normalized, or at least mitigated, during a 24 h bed rest. The results of the study show that the circadian rhythm of Na+ excretion are disturbed already in the initial stage of hypertension. The likely cause is the exaggerated rise in adrenergic activity in the kidney during the day, induced by orthostasis and the concomitant physical (and mental?) activity, which is inadequately compensated for by the activation of natriuretic mechanisms.

Changes in the EEG spectrum at a two-week intensive endurance training.

Marathon runners in the course of a two-week endurance training, (i.e. in the beginning, after one and after two weeks) and processed by the off-line method of fast spectral analysis. Simultaneously biochemical parameters were monitored which indicated after one week the development of the so called "pseudouremic syndrome of top athletes" of not too great intensity. In the second week of the experiment therapeutic intervention was made in six subjects, i.e. reduced protein supply, greater amount of glucose, application of Ca-lactate and higher amount of liquids. This intervention eliminated entirely the signs of pseudouremic syndrome. The EEG showed in both groups a decrease in theta activity (4-6 Hz) and an increase of the slow alpha component and subtheta activity (6-8 Hz), with no basic difference between the intervened and control group. Thus the changes may be rather attributed to fatigue and perhaps to a poorer supply of the CNS with oxygen and glucose.

The effect of glucagon on myocardial metabolism in diagnostic cardiac pacing.

Nine patients with the angina pectoris syndrome in the absence of a history of demonstrable myocardial infarction were examined twice at rest and during cardiac pacing at 13-min intervals. Glucagon (0.5 mg/50 ml saline) was applied before the second examination. The authors investigated the differences of lactate (La) and lactate-pyruvate ratio (La:Py) between arterial blood and coronary sinus (a-cs diff) and the values of serum transaminases and glycaemia. A negative La and/or La:Py a-cs diff during or after pacing was interpreted as a positive qualitative sign of induced acute myocardial ischaemia. Application of glucagon on the second cardiac pacing led to worsening of the metabolic situation in 71% of patients; none of the patients showed improvement. The La:Py a-cs diff after glucagon was negative in all patients.

The effect of stress on circadian rhythms.

The authors chose four types of intensive stress in man and show their effect on the circadian rhythms of selected parameters. Sleep deprivation reduces mean sideraemia and oscilation amplitudes. The morning rhythm maximum shifts to early morning hours. Acute fasting does not change the biorhythm of serum iron despite that mean sideraemia increases. On the other hand, realimentation is associated with a marked drop of iron level and a shift of the morning maximum to early afternoon hours. Stress induced by isolation in humid warm environment initiates a decrease of systolic blood pressure. While biorhythm amplitude remains unchanged peak systolic pressure moves from the usual 18 to 20 hours up to 23 to 24 hours. Stress caused by diagnostic cardiac catheterization results in biorhythm inversion of the urinary excretion of catecholamines and 17-OH-corticoids. On the day of catheterization, performed in all cases in the morning hours, the usual morning peak values of adrenaline shifted to afternoon hours and those of noradrenaline and 17-OH-corticoids even to late night hours. For practical purposes, biorhythm changes can be used as indicators of the effect and intensity of stress.

Effects of sleep deprivation on the activity of selected metabolic enzymes in skeletal muscle.

The effect of 120-h sleep deprivation on the activity of selected enzymes of energy metabolism in skeletal muscle was studied in seven healthy volunteers. The results showed a significant decrease in the activity of malate dehydrogenase, citrate synthase, glycerol-3-phosphate dehydrogenase and lactate dehydrogenase. Triosephosphate dehydrogenase, hexokinase, and hydroxyacyl-CoA-dehydrogenase activities showed an insignificant decrease. The findings are indicative of (1) decreased aerobic oxidation capacity; (2) reduced function of reducing-equivalent carriers from cytosol across the mitochondrial membrane; (3) relative accentuation of the non-aerobic glycolytic pathway; (4) a prediabetic type of muscle metabolism.