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Biomedical subjects

M Lehmann

Publications and source records attributed to M Lehmann.

At least 271 records · Page 15Linked to original sources
PubMed1986

Urinary excretion of free noradrenaline and adrenaline related to age, sex and hypertension in 265 individuals.

Urinary excretion of free noradrenaline and adrenaline during 24 h in 265 individuals was determined and related to sex, age, and hypertension as one indicator of the average sympathetic drive. Noradrenaline was found to correlate positively with age in healthy individuals. Noradrenaline and adrenaline were lower in healthy women than in men during the first half of life expectancy. Catecholamine excretion was similar in men and women in the second half of life expectancy. In hypertensive individuals, catecholamine excretion was slightly higher in the first half, and significantly higher in the second half of life expectancy. We assume that the differences in catecholamine excretion can contribute to the sex-and age-related differences in incidence of cardiovascular diseases, such as hypertension and coronary heart disease.

Adult↗
PubMed1986

Sex-related differences in free plasma catecholamines in individuals of similar performance ability during graded ergometric exercise.

Sex-related differences of catecholamine responses were evaluated in nine healthy women and six age-matched men at rest and during incremental treadmill exercise. Heart rate, oxygen uptake (VO2), glucose and lactate blood levels as well as the free plasma catecholamines, noradrenaline and adrenaline, were determined. No significant differences were observed for these parameters between the two groups at rest. The females had relative VO2max and maximal running velocities similar to the males, which points to a comparable dynamic performance ability. However, at identical work loads, noradrenaline, adrenaline and glucose levels were significantly higher in women than in men. Lactate, heart rate and relative VO2 showed a similar tendency at submaximal exercise levels, indicating higher strain at identical stress levels in women. The reason for the higher sympathetic activity in women at identical work loads may be their relatively smaller skeletal muscle mass in relation to the loads during this test.

Adult↗
PubMed1986

Age-associated changes of exercise-induced plasma catecholamine responses.

Age-associated plasma catecholamine responses were evaluated in 10 young (25 +/- 3 years) and 11 older competition cyclists (66.2 +/- 6 years) during incremental ergometric cycling. Noradrenaline levels were higher in the older subjects at rest, at identical work loads and at exhaustion. Adrenaline levels were similar in both groups at rest, higher in the old test subjects at identical work loads and lower in the old subjects at exhaustion. The noradrenaline-adrenaline ratio changed significantly depending on age from 5.1 +/- 0.5 to 8.7 +/- 2.1 which indicated higher adrenaline-related noradrenaline responses. The observed age-related differences may be caused by a compensatory mechanism which depends both on negatively age-correlated physical fitness, and on the decreased sensitivity of the organism to beta-adrenergic stimulation with age, as well as on an age-dependent change in the clearance of catecholamines from the circulation as described by Esler et al. (1981).

Adult↗
PubMed1986

Modification of suppressor/cytotoxic and helper subsets in lentil lectin-pretreated mice.

The effect of lentil lectin (LCA) on various lymphocyte subpopulations in the spleen, lymph nodes and thymus of CBA mice was studied. The most marked effect after five 1-mg LCA doses was observed in the spleen. LCA caused a drop in both the total and relative number of cells carrying all the markers examined, i.e., Thy 1, L3/T4a, Lyt 2, and sIg, so that large numbers of lymphocytes did not express any of them. A dramatic decrease in the Thy 1-positive cell number is mainly due to depletion of the L3/T4a (helper) T cell subpopulation, whereas the Lyt 2+ (suppressor/cytotoxic) cells are less affected. The decrease in the Thy 1+, Lyt 1+ and L3/T4a+ cell numbers in the thymus and lymph nodes is smaller, the percentage of Lyt 2+ cells is even increased after LCA treatment. Our results indicate that two mechanisms play a role in the induction of allotransplantation tolerance by LCA: 'depletion' of helper T cells and a relative increase in the regulatory (suppressor) cell ratio, which may support allograft survival.

Animals↗
PubMed1986

Hypoglycemia following insulin and proinsulin. A comparison.

The counterregulatory hormonal response to proinsulin-induced hypoglycemia was investigated in eight volunteers. Proinsulin cleared slower from the circulation than insulin. Hypoglycemia occurred slower (2P less than 0.005) and was prolonged, while the overall hypoglycemic activities were comparable. The antilipolytic effect of proinsulin was also prolonged (2P less than 0.001). The response of epinephrine to hypoglycemia was less pronounced after proinsulin (2P less than 0.05). The amount of epinephrine was correlated to the rate of fall in plasma glucose (P less than 0.005). The production of lactate induced by beta-stimulation was also correlated to the fall of glucose (P less than 0.005). The responses of prolactin (2P less than 0.02), norepinephrine (2P less than 0.02), cortisol, and growth hormone were attenuated following proinsulin. The decreases of serum potassium and serum phosphate (2P less than 0.05) were less pronounced. Symptoms like sweating (2P less than 0.01) and dizziness (2P less than 0.01) were milder after proinsulin. It is concluded that the rate of fall in glucose concentration determines the differing counterregulatory responses. We don't relate the differing counterregulatory responses to special insulin-like properties of proinsulin, but to the slower kinetics which is emphasized by the intravenous bolus injection.

3-Hydroxybutyric Acid↗
PubMed1986

Free plasma catecholamines, heart rates, lactate levels, and oxygen uptake in competition weight lifters, cyclists, and untrained control subjects.

Responses of free plasma noradrenaline and adrenaline were evaluated in 10 competition cyclists, 8 competition weight lifters, and 9 untrained control subjects during exhaustive, incremental cycling. Ergometric performance and oxygen uptake ability were 403 +/- 20 W and 65.8 +/- 4.7 ml X kg-1 for the cyclists, 294 +/- 42 W and 47.2 +/- 4.6 ml for the weight lifters, and 296 +/- 40 W and 46.7 +/- 9.4 ml for the control subjects. At 100- and 150-W levels, noradrenaline was significantly lower in cyclists and weight lifters, and in cyclists also at 200- and 250-W levels, related to the other groups. No significant noradrenaline differences were seen between the three groups at their respective exhaustion levels. Compared with the control subjects, adrenaline responses were lower in cyclists and weight lifters at all identical work loads. The weight lifters showed the lowest levels of all three groups, even at their exhaustion level, which indicates an alteration of the adrenaline-noradrenaline ratio. Dynamically and statically trained subjects exhibit a similar training-related control of sympathetic activity. An increased vagal tone, however, only occurs in conjunction with dynamic endurance training.

Adult↗
PubMed1986

Alpha-2-adrenoreceptor density on intact platelets and adrenaline-induced platelet aggregation in endurance- and nonendurance-trained subjects.

Alpha-2-adrenoreceptor density on intact platelets was evaluated in 17 sportsmen, 8 of whom were endurance-trained athletes. Receptor density was determined as being equivalent to 3H-Yohimbine, specifically bound on intact platelets. Adrenaline-induced aggregation of platelets in vitro was additionally ascertained. Bmax (maximal binding) and KD (dissociation constant) were significantly lower in endurance-trained athletes (148 fmol per 10(9) platelets, KD = 0.92 nmol) than in the nine nonendurance-trained individuals (284 fmol, KD = 1.79 nmol, P less than 0.01), amounting to 89 receptors per cell (endurance-trained subjects) and 171 (nonendurance-trained subjects). No significant change of receptor density or affinity was observed subsequent to exhaustive exercise in the group of eight endurance-trained individuals. Bmax values and oxygen uptake capacity correlated negatively (r = -0.78, P less than 0.001) and Bmax values and induced platelet aggregation in vitro positively (r = 0.79, P less than 0.001). Data may indicate a reduced sensitivity of platelets in endurance-trained subjects.

Adult↗
PubMed1986

The influence of forskolin on the metabolism of ecdysone and 20-hydroxyecdysone in isolated fat body of the blowfly, Calliphora vicina.

Rates of ecdysone and 20-hydroxyecdysone metabolism were measured by radio-assay in an in vitro system containing fat body isolated from blowfly larvae. The addition of forskolin which is known to stimulate artificially the intracellular adenylate cyclase system led to decreased rates of conversion of ecdysone into 20-hydroxyecdysone (= hormone activation) and of 20-hydroxyecdysone further to other metabolites (= hormone inactivation). The effect of forskolin was dose-dependent and reversible. Extracts prepared from larval brains were also tested. Some of them had the same effect as forskolin. It is concluded that the reactions leading from ecdysone to 20-hydroxyecdysone and further to hormonally inactive ecdysteroids are modulated by the intracellular level of cyclic nucleotides. We propose that a neurohormone is involved in the control of the reactions of the ecdysone metabolism. The observed new principle may contribute to the control of the titer of moulting hormone.

Adipose Tissue↗
PubMed1986

[The effect of the cell separation procedure on neutrophilic granulocyte function. I. Research on the morphology and phagocytosis behavior of isolated granulocytes].

The investigations were aimed at detecting the impact of various cell separating techniques on the morphology and function of neutrophilic granulocytes. Methodically simple cell separating techniques were used, such as spontaneous sedimentation of ACD-AG blood and mechanically defibrinated blood and a flotation technique which makes use of cell isolation by means of a separating solution and centrifugation. Granulocytes which were isolated by the cell separator Haemonetics M 30 for therapeutic purposes and which, according to data in literature, are not damaged by cell separating techniques were used as reference cells. The electronic-optical evaluation of granulocyte morphology and the in vitro investigation of the phagocytic capacity for rice starch (ingestion rate) of differently isolated granulocytes were made after cell separation.

Cell Separation↗
PubMed1986

[The effect of the cell separation procedure on neutrophilic granulocyte function. II. Research on the bactericidal capacity and the NBT reduction ability of isolated granulocytes].

The investigations were aimed at examining the impact of methodically simple separating and enriching techniques for gaining granulocytes on the bactericidal capacity and NBT reduction in isolated granulocytes. For this purpose, granulocytes were gained by the technique of sedimentation and flotation. Granulocytes isolated by the cell separator Haemonetics model 30 were used as reference material. The findings of the investigations together with those of previous studies revealed no indication of the granulocyte function and morphology being damaged by the separating techniques used.

Blood Bactericidal Activity↗
PubMed1986

[Stress-induced changes in the spleen and thymus of the mouse after skin transplantation].

The influence of the unspecific stress factors at the distribution of the lymphocyte subpopulations in spleen and thymus was investigated in skin transplantation model of the mouse after operation. The parameters total lymphocyte content, electrophoretic distribution pattern, activity and isoenzyme pattern of the LDH were compared in allogenic, syngenic, and sham transplanted mice with untreated control animals. Stress reactions were observed in the electrophoretic distribution pattern of the spleen cells as an increase of the quickly moving fraction (S-fraction) still on the 14th day after transplantation. Such reactions as an increase of the S-fraction were provable in the thymus cells on the 3rd and 7th day. The influence of the operation stress was further shown in a changed isoenzyme pattern of the thymus cells LDH. The relative portions of the LDH 1 and LDH 2 were reduced still 10 days after transplantation with an increase of the LDH 5.

Animals↗
PubMed1986

[Primary orthostatic hypotension].

We studied a 25-year-old man suffering from primary orthostatic hypotension whose blood pressure decreased to 65/45 mm Hg during orthostasis and to 95/70 mm Hg during ergometric exercise (50 and 100 watt), and whose heart rate responses were inadequate. Resting catecholamine levels were within the normal range and did not show any significant increase related to orthostasis or to ergometric exercise. Hypersensitivity was observed to low doses of intravenous noradrenaline and isoproterenol. Specific binding of 3H-Yohimbine to intact platelets revealed a normal number of alpha-2-adrenoreceptors in agreement with the adrenaline-induced platelet aggregation in vitro, which was, however, in contrast to hypersensitivity to noradrenaline. Specific 3H-Dihydroalprenolol binding to intact polymorphonuclear leucocytes revealed an increased beta-2-adrenoreceptor density in agreement with hypersensitivity to Isoproterenol. Prescription of Fludrocortison improved orthostatic hypotension.

Adult↗