Search PubMed⌕ Search

Biomedical subjects

J Marbach

Publications and source records attributed to J Marbach.

23 records · Page 2Linked to original sources
PubMed1986

Work rate-dependent lactate kinetics after exercise in humans.

Arterial blood lactate concentrations were measured on 19 subjects before, during, and after a 3-min bicycle exercise at several work rates, and the concentrations during the recovery phases were fitted to a biexponential time function consisting of a rapidly increasing and a slowly decreasing component. Highly significant correlations with the work rate of the exercise preceding the recovery were found for all the parameters of the fitted equation. The two velocity constants show inverse linear relationships, whereas the other parameters vary according to a definite power function. A functional meaning has been given to the two velocity constants, namely the ability of the tissues to exchange and to remove lactate. For the group of subjects studied, after exercises at work rates below about 3.5 W/kg, the tissue's ability to utilize, and possibly to exchange lactate, increases over values generally reported for resting conditions, whereas after exercises at higher work rates the inverse occurs. Lactate kinetics during recovery appear to be the result of two underlying processes, one enhancing the ability of the tissues to exchange and remove lactate and the other restraining it.

Adult↗
PubMed1980

Blood pyruvate recovery curves after short heavy submaximal exercise in man.

Arterial pyruvate and lactate concentrations were measured after short heavy submaximal exercise on a bicycle ergometer, at 10 or 30 s time intervals, on six male subjects. During most of the first 2 min of recovery pyruvate concentration decreased. Thereafter, it increased and reached its maximum within the 5th to 9th min of recovery. Finally, it decreased gradually as a function of time. Recovery curves could be accurately described after a short delay time following the end of the exercise, by a sum of three exponential terms according to the equation: (Formula: see text), where the time origin (to) is fixed at about 1-1.5 min(delay time) after the end of exercise, t is the time after to, Y(O) and Y(t) are the concentrations of pyruvate respectively at times zero and T, and Ai and zi are constants. The velocity constant of the final arterial blood pyruvate decrease was similar to that of the simultaneously measured lactate, indicating that the rate of lactate removal is closely related to that of pyruvate. This is consistent with the fact that pyruvate is a necessary intermediate in the lactate metabolism.

Adult↗
PubMed1979

Effects of biguanides on the intermediate metabolism of glucose in normal and portal-strictured rats.

Phenformin and metformin treatments may be complicated by lactic adidosis. This metabolic complication seems favoured by preexistent hepatic disease. We have therefore compared the metabolic effects of phenformin and metformin on non fasting normal and portal-strictured rats. The latter group is characterized by impaired hepatic passage of these drugs without hepatocellular lesions. Given orally to normal rats over 5 days, phenformin (20 mg/kg/24 h) and metformin (150 mg/kg/24 h) decreased blood glucose levels and increased blood urea and the substrates of gluconeogenesis (alanine, glutamine, lactic and pyruvic acids), effects more apparent with phenformin than metformin. In non-treated portal strictured rats, blood glucose levels were lower and the intermediate metabolites were higher than in noraml rats, suggesting a modification of gluconeogenesis. Treatment of the portal strictured group by phenformin or metformin induced no changes in the studied parameters. This absence of effect of the biguanides in portal strictured rats supports the postulate that, in normal rats, biguanides act principally on hepatic metabolism by reducing gluconeogenesis and that, in the absence of other hepatic damage, the presence of a peri-hepatic shunt, which, by itself, modifies gluconeogenesis, does not further predispose to lactic acidosis during short term administration of biguanides.

Alanine↗
PubMedDate not supplied

Psychoneuroimmunology: potential relevance to chronic orofacial pain.

Studies undertaken over the past ten years have demonstrated that stress and depression can induce immune alterations, including decreased numbers of immunocompetent cells and impaired lymphocyte and natural killer cell activity. Factors such as age and severity of symptomatology influence these effects. The substantial stress and depression associated with chronic pain syndromes and the evidence for opioid involvement in immunomodulation suggest that immune system changes may occur in some patients with chronic facial pain.

Animals↗