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Biomedical subjects

B Diamant

Publications and source records attributed to B Diamant.

At least 19 recordsLinked to original sources
PubMed1992

Ischaemic heart disease, skeletal muscle fibres and exercise capacity.

Twenty-eight male patients with ischaemic heart disease (IHD) performed OBLA (onset of blood lactate accumulation) exercise stress tests and had muscle biopsies taken from their vastus lateralis muscle the day before coronary bypass grafting. All 28 patients showed the same exercise performance pattern as compared to healthy sedentary, age-matched, controls: a low exercise intensity eliciting a blood lactate concentration of 2.0 mmol x l-1 (WOBLA), WOBLA corresponded to a high fraction (% WOBLA) of WSL (symptom limited or 'maximal' capacity), and a low peak blood lactate concentration. The high % WOBLA and low peak blood lactate indicated a reduced glycogenolytic capacity ('anaerobic' performance). Muscle fibre composition disclosed a high mean value of fast twitch (FT), type II or 'white' muscle fibres, as compared to sedentary healthy controls. This indicated that this patient group constituted an extreme subgroup of the age-matched population. The distorted muscle fibre composition in IHD could reflect both heredity as well as adaptation to physical inactivity, degenerative cytosolic properties, etc. Muscle and blood contents of a mitochondrial electron translocator and nonspecific radical scavenger, ubiquinone or coenzyme Q10(CoQ10), were low, which coincided with an elevated frequency of the fibre subgroup FT(c). The presence of the FT(c) fibre type is assumed to reflect histological trauma.

Adult↗
PubMed1992

Exercise-limiting factors in respiratory distress.

Exercise performance data, circulatory function and respiratory and leg muscle quality, expressed as muscle fiber composition, are reviewed and together with our own data discussed as possible limiting factors for physical performance in chronic obstructive pulmonary disease (COPD). COPD is regarded as synonymous with reduced physical performance, exaggerated breathlessness or dyspnea, muscle hypotrophy and/or wasting and, frequently, malnutrition. Impaired right ventricular circulatory function seems to be essential. The observed preponderance of fast twitch (FT), 'glycogenolytic' and capillary-poor muscle fiber type in the investigated muscles might reflect endowment, a 'hypoxic vasoconstriction'-related downregulation of the other main fiber type: the slow twitch (ST), capillary-rich, fatigue-resistant fiber, and/or selective muscle trauma to ST fibers. Ischemic heart disease (IHD) patients demonstrate a similar fiber type pattern in leg muscles. Both COPD and IHD patients have low leg muscle and plasma deposits of antioxidants such as coenzyme Q10 (CoQ10) and alpha-tocopherol. This could reflect a depressed resistance to radical induced cell trauma and/or malnutrition. The magnitude of the antioxidant reduction is less pronounced in patients rich in FT fibers indicating a ST fiber-related susceptibility to trauma. Treatment of other muscle disorders including heart muscle with, e.g., CoQ10 improves performance due to a causative enhanced antioxidant potential, reduced catabolism and/or an upregulated muscle anabolism, increased mitochondrial volume/function, etc. Such data are lacking in COPD.

Aged↗
PubMed1992

Plasma ubiquinone, alpha-tocopherol and cholesterol in man.

Plasma ubiquinone, coenzyme Q10 or CoQ10 has been analyzed in plasma together with alpha-tocopherol and free cholesterol in healthy sedentary male subjects (SS), endurance trained male athletes (ET) and male patients with severe ischemic heart disease (IHD). Higher means were found in SS compared to both IHD and ET. Moreover, the ratios CoQ10 and alpha-tocopherol over free cholesterol were higher. In all groups significant relationships were found between the two products of the mevalonate pathway: CoQ10 and cholesterol (r ranged 0.66-0.86, p less than 0.01). The two lipophilic antioxidants, CoQ10 and alpha-tocopherol, were interrelated only in IHD (r = 0.86, p less than 0.001), borderline in SS (r = 0.51, p less than 0.05) but not in ET. It is assumed that plasma free cholesterol reflects the capacity to transport lipids and lipophilic compounds in blood. With metabolic stress and an elevated radical formation as in IHD and ET, the lower CoQ10 and alpha-tocopherol to cholesterol ratios mirror a subsequent toll on the scavenging potential. The difference in LDL levels between IHD and ET and the different storage capacity of CoQ10 and alpha-tocopherol might explain the tight coupling in IHD but not in ET. It is possible that the toll reflects both an intra- and extracellular radical quenching activity. The joint effect of the two lipophilic, extracellular antioxidants CoQ10 and alpha-tocopherol role in protecting e.g. LDL particles from peroxidation is suggested.

Cholesterol↗
PubMed1991

Effects of N-acetylcysteine on histamine release by sodium fluoride and compound 48/80 from isolated rat mast cells.

N-acetylcysteine (NAC) enhances the release of histamine induced by the fluoride-calcium system but not by compound 48/80. After preincubation of the cells for 2 h at room temperature (RT) as well as at 37 degrees C, NAC was found to enhance histamine release also when induced by compound 48/80. Both fluoride treatment and prolonged incubation at 37 degrees C (but not at RT) for 2 h decreased the ATP content of the cells. NAC was found to counteract the fall in ATP caused by prolonged incubation of the cells at 37 degrees C but not when induced by exposure to sodium fluoride. The results do not favor the concept that free radicals generated by fluoride treatment are responsible for the subsequent sensitivity of the cells to the secretory action of calcium. On the other hand, it cannot be excluded that free radicals generated during prolonged incubation of the cells at 37 degrees C might be involved in the decrease of the sensitivity of the cells to the secretory action of the fluoride-calcium system and of compound 48/80. This is supported by the finding that the presence of NAC not only activated the secretory response but also counteracted the decrease of the cellular ATP content noted following preincubation of the cells for 2 h at 37 degrees C.

Acetylcysteine↗
PubMed1991

Muscle fibre types, ubiquinone content and exercise capacity in hypertension and effort angina.

The composition of skeletal muscle fibre expressed as a percentage of slow twitch (ST), type I or "red" and fast twitch (FT), type II or "white" were determined in patients with hypertension (HT) or with severe ischaemic heart disease (IHD) and compared to age matched controls. Similarly, exercise capacity expressed as the cycle intensity eliciting a blood lactate concentration corresponding to 2.0 mmol x 1-1 were compared with healthy controls. Both patient groups had a higher percentage of FT fibres with relatively lower exercise capacities than their controls. The exercise capacities were reduced even when the relationship of decreased capacity with the percentage of increased FT was considered. There was an increase IHD but not in HT in patients with fibre subgroup FTc, which most probably reflected fibre trauma. Both patient groups were low in the skeletal muscle mitochondrial electron carrier and unspecific antioxidant ubiquinone, coenzyme Q10 or CoQ10. Patients with IHD but not HT showed, however, a faster fall in the ratio CoQ10 over ST% the higher the percentage value of ST. The ratio reflects the antioxidant activity related to CoQ10 in the fibre hosting most of the oxidative metabolism. A low ratio indicates a risk of metabolic lesion and cell trauma. This could explain fibre plasticity and offer an alternative cause to heredity in elucidating in deviating muscle fibre composition in patients with HT and IHD.

Adult↗
PubMed1991

Coenzyme Q10, alpha-tocopherol and free cholesterol in HDL and LDL fractions.

Twenty-three randomly selected plasma samples from apparently healthy, middle aged men were analysed for coenzyme Q10 (CoQ10), alpha-tocopherol (AT) and free cholesterol (FC) in: 1) whole plasma, 2) the HDL lipoprotein fraction after LDL precipitation (VLDL + LDL). CoQ10, AT and FC in plasma averaged 0.69 +/- .11, 6.74 +/- 1.78 micrograms x ml-1 and 0.59 +/- .11 mg x ml-1 and in HDL 0.17, 3.24 micrograms x ml-1 and 0.17 mg x ml-1 or 29, 48 and 29% of plasma values. Amounts of CoQ10 and AT were correlated to that of FC in all pools. The amount of HDL-CoQ10 but not of HDL-AT fell, with the HDL-FC expressed as the fraction of plasma FC. In all pools, N-AT versus AT initially increased and then levelled off, indicating saturation like conditions in contrast to CoQ10. Thus, CoQ10 and AT are differently allocated in HDL and LDL. This might have a bearing both on the suggested lipoprotein protection against peroxidation by these two antioxidants, but also on the distribution and allocation in different organs of CoQ10 and AT by HDL and LDL transportation.

Cholesterol↗
PubMed1991

Muscle mass effect on arterial desaturation after maximal exercise.

We measured arterial oxygen saturation before and immediately after randomly allocated 6 min of "all-out" maximal arm cranking, treadmill running, and ergometer rowing in 10 men and women with a median maximal oxygen uptake of 4.47 (range 3.22-5.34) 1.min-1. Arterial saturation for oxygen was unaltered after arm cranking, but decreased 1.7 (-2.5-6.0) % (P less than 0.05) after running, and 2.2 (1.0-8.7) % (P less than 0.01) after rowing. Arterial saturation was inversely related to capillary blood lactate, which reached 11.8 (7.4-14.0), 12.6 (8.9-18 2), and 14.3 (12.0-19.3) mmol.l-1 (P less than 0.01), respectively, and arterial bicarbonate fell to 15.0 (13.0-23.6), 12.4 (7.2-20.4), and 10.8 (0.0-12.5) mmol.l-1 (P less than 0.01). Thus, pH decreased to 7.25 (7.22-7.40), 7.17 (6.95-7.35), and 7.09 (6.84-7.19) (P less than 0.01). When measured immediately post-exercise, arterial oxygen tension was unchanged or elevated from rest, eliminating the possibility that the arterial desaturation was caused by a pulmonary diffusion limitation. The results of this investigation show that arterial desaturation associated with maximal exercise takes place in proportion to the involved muscle mass, as do deviations in blood lactate, bicarbonate, and hydrogen concentrations.

Adult↗
PubMed1990

Effects of long-term coenzyme Q10 and captopril treatment on survival and functional capacity in rats with experimentally induced heart infarction.

The effects of coenzyme Q10 (CoQ) and captopril on functional capacity, hemodynamics and survival were studied in 154 rats that recovered after experimental myocardial infarction. Rats were randomized into four groups receiving either CoQ, captopril, a combination of the two drugs or 1 ml of tap water once daily for 12 weeks from the day of coronary artery ligation. CoQ as well as captopril and the combined treatment significantly improved exercise capacity as evaluated by lactate production during a standardized treadmill exercise test. No significant changes in heart rate or mean blood pressure were observed during the study in the captopril-treated group. CoQ treatment increased the maximum heart rate significantly, whereas no effect on mean blood pressure was observed. Both captopril and CoQ decreased pulmonary congestion. Furthermore, the data may suggest that captopril prevents right ventricular hypertrophy seen in placebo-treated rats with large infarcts. This was not observed after CoQ treatment. Captopril treatment improved 3-month probability of survival (93%) as compared with placebo (74%) (P less than .05). CoQ and the combined treatment tended to improve survival, but this was, however, not statistically significant.

Animals↗
PubMed1989

Isolation of cardiac ventricular myocytes from newborn rats by use of fractional elutriation centrifugation.

Isolation of cardiac ventricular myocytes from newborn rats (0-4 days old) by use of elutriation centrifugation is described. By the use of fractional centrifugation, a homogeneous myocyte population with high purity was obtained without any further procedures, yielding about 10(6) myocytes/rat. When 48-hr monolayer cultures were established, the cells showed normal pulsatory contractions. A morphological evaluation of such cultures is given.

Animals↗
PubMed1989

Time course of functional deterioration after coronary artery ligation in rats.

The aim of this study was to investigate the time course of deterioration of functional capacity in the rat after ligation of the left coronary artery. Functional capacity was evaluated from the increase in blood lactate concentrations in 109 rats during a standardised treadmill test. Animals with myocardial infarction were compared with sham operated and normal controls. Functional capacity was followed during a 13 week period and estimations of the functional capacity were performed 1, 3, 7, 9 and 13 weeks after infarction. Coronary artery ligation produced a significant reduction in functional capacity, averaging 47% (p less than 0.01) over the first 3 weeks after myocardial infarction, irrespective of infarct size. In rats with large infarcts, functional capacity remained essentially unchanged throughout the observation period, but rats with small infarcts improved gradually until their measured exercise response was completely normal at the end of the 13 week period.

Animals↗
PubMed1988

Ergogenic effect of inhaled beta 2-agonists in asthmatics.

To investigate the effect of beta 2-agonists on exercise performance, eight asthmatics performed an incremental exercise test on a treadmill. Five minutes before the start of the exercise, they were treated with inhaled salbutamol or placebo in a double-blind manner. The exercise started at a low intensity (2 mph, 10% inclination), and every 3 min the speed was increased by 0.5 mph at the same inclination until the subjects were exhausted. Every minute peak expiratory flow, heart rate, blood lactate concentration, and rating of perceived exertion were measured. The same parameters were also measured following the completion of the exercise. No significant difference was seen in total working time, maximal lactate concentration, heart rate, or rating of perceived exertion, whereas the decrease in peak expiratory flow was reduced following pretreatment with salbutamol. It is concluded that the release of inhaled beta 2-agonists for use in competitive events is justified as no ergogenic effect was seen.

Adrenergic beta-Agonists↗
PubMed1988

Beta 2-mediated changes in central haemodynamics, coronary circulation and myocardial metabolism in canine.

The combined effect of terbutaline on systemic and coronary circulation was investigated in dogs to clarify its influence on myocardial oxygen supply and lactate balance. The dogs were anaesthetized and the chest opened. Coronary sinus blood flow and cardiac output were monitored by thermodilution, aortic pressure was measured by tip-transducer and heart rate by RR-interval on ECG, coronary sinus blood were analyzed for lactate, oxygen and carbon dioxide. Terbutaline caused a substantial systemic vasodilation and an increased heart rate, the total external cardiac work increased to a minor degree. Terbutaline increased arterial lactate concentration. Coronary vascular resistance was reduced after terbutaline. Even if myocardial perfusion pressure was reduced and an increased external cardiac work was present, no signs of myocardial distress was observed in lactate metabolism or coronary sinus oxygen content. In fact a tendency to increased myocardial aerobic metabolism was observed, as myocardial lactate consumption increased after terbutaline. Terbutaline seems to be a coronary vasodilator in dogs. However, the demand for oxygen secondary to both an increase in cardiac work and aerobic metabolism can be hazardous to the potentially ischaemic myocardium.

Animals↗
PubMed1984

Inhibitory effect of aprotinin on gastric acid secretion.

Aprotinin was found to inhibit the amplitude of electrically stimulated contractions of the isolated guinea pig ileum with an ID50 of 6.75 X 10(-6) M. Aprotinin inhibited pentagastrin-stimulated gastric acid secretion in the rat, cat, and pig after oral or intraventricular administration. No inhibition of gastric acid secretion was seen after intravenous infusion of aprotinin. When segments of antrum, duodenum, and ileum were incubated in vitro with increasing concentrations of aprotinin, increasing amounts of somatostatin were released from the organs. It is suggested that aprotinin's effects, which are similar to those of somatostatin, may be due to a local release of somatostatin from the D-cells in the gastrointestinal tract.

Animals↗
PubMed1983

Dissociation of the spasmolytic and metabolic effects of glucagon.

Glucagon and glucagon-(1-21)-peptide were equipotent with regard to inhibitory effect on the amplitude of electrically evoked contractions of the isolated guinea-pig ileum. The effect was not potentiated by isobutylmethylxanthine (IBMX) nor inhibited by phentolamine or propranolol. Both peptides inhibited intestinal motility in rabbits in vivo. Glucagon and equimolar doses of glucagon-(1-21)-peptide exerted a relaxing effect on the rabbit gall bladder in vitro and in vivo and increased bile flow in rats. Both peptides inhibited pentagastrin stimulated gastric acid secretion in cats. However, contrary to glucagon, glucagon-(1-21)-peptide did not increase blood glucose and plasma IRI levels after intravenous administration to rats in vivo. Whereas the entire glucagon molecule was required for the metabolic effects, the amino acid sequence (1-21) of glucagon exerted a full spasmolytic action on the enteric muscles and the biliary tree. The spasmolytic effects on these organs are therefore likely to be mediated via a mechanism that does not involve the activation of adenyl cyclase.

Animals↗