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Biomedical subjects

M Rothschild

Publications and source records attributed to M Rothschild.

At least 55 records · Page 3Linked to original sources
PubMed1989

Alpha 2- and beta 2-adrenoceptor downregulation in marathon runners.

The regulation of platelet alpha 2- and lymphocyte beta 2-adrenoceptor densities by alterations in endogenous catecholamines was examined. In order to activate the sympathetic nervous system eight trained male normotensive subjects carried out a marathon run. Adrenoceptor densities and plasma catecholamine concentrations were measured before and immediately after the run. Platelet alpha 2-adrenoceptor density and lymphocyte beta-adrenoceptor density decreased after the run (P less than 0.05), whereas both plasma noradrenaline and adrenaline concentrations increased (P less than 0.01). Mean arterial pressure decreased (P less than 0.05), and the heart rate increased (P less than 0.001). The data suggest that increases in endogenous catecholamine concentrations cause downregulation of both alpha- and beta-adrenoceptor densities on human blood cells.

Adult↗
PubMed1989

Depression in obese men.

Using the Beck depression inventory (BDI), we studied depression in young, healthy, male subjects who represented a wide range of body weight. Body mass index (BMI), defined as the weight (in kilograms) divided by the square of height (in meters), was used to classify subjects as obese (BMI greater than 31.1, n = 27), overweight (BMI = 27.8-31.1, n = 10) or acceptable weight (BMI less than 27.8, n = 26). BDI scores of 0-9 indicated no depression; scores of 10-15 indicated mild depression. BDI scores from 16 to 63 indicated increasing depression. No group of subjects (obese, overweight or acceptable weight subjects), had mean BDI scores suggesting depression. The mean BDI score for the obese subjects was 5.6 +/- 0.8 (mean +/- s.e.m.), which was significantly higher than the mean BDI scores for both the overweight subjects (2.5 +/- 1.1; P less than 0.04) and the acceptable weight subjects (1.5 +/- 0.3; P less than 0.001). There was a weak positive correlation of BDI with BMI (n = 63, r = 0.404, P less than 0.001). In addition, the obese subjects did form a heterogeneous group with four obese subjects (14.8 percent) having BDI score of 10 or greater. The overweight subjects had one subject (10 percent) with a BDI score of 12. None of the acceptable weight subjects had a BDI score of greater than 5. There was no correlation between waist/hip ratios and BDI scores (n = 37, r = 0.262, P = 0.118). We conclude that mild depression is present in some obese persons even when medically healthy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Different effects of furosemide on alpha-adrenoceptors and on platelet aggregation in man.

The effect of a long-term administration of furosemide (2 x 30 mg/day for 3 weeks) on platelet alpha 2-adrenoceptor density and the fraction of high-affinity binding sites, as well as on platelet aggregation induced by adrenaline and ADP, was studied ex vivo in 8 normotensive volunteers. For comparison the in vitro effect of furosemide on platelet aggregation was also evaluated. Furosemide decreased alpha 2-adrenoceptor-density (P less than 0.01) and the fraction of high-affinity binding sites (P less than 0.05). Adrenaline-induced platelet aggregation was not altered ex vivo and in vitro. Furosemide inhibited ADP-induced platelet aggregation ex vivo (P less than 0.05) and in parallel in vitro (P less than 0.01) in a dose-dependent manner. The reduction of the density of alpha 2-adrenoceptors in the high affinity state may be of functional importance for the hemodynamic effects of furosemide. The inhibitory effect of furosemide on ADP-induced platelet aggregation ex vivo and in vitro, which is not related to the effects on adrenoceptors, seems to involve direct effects of furosemide on platelet function. It remains to be seen whether the latter effect is of clinical importance.

Adult↗
PubMed1988

Body fat and the activity of the autonomic nervous system.

The cause of most cases of human obesity is unknown. Specific alterations in the activity of the autonomic nervous system may mediate and perhaps cause obesity in animal models. We therefore looked for alterations in autonomic activity in human obesity. Fifty-six healthy men with various percentages of body fat underwent autonomic testing while at rest. Significant correlations were found between the percentage of body fat and the variation in the R-R interval after beta-adrenergic blockade (r = -0.30, P less than 0.03), the heart rate (r = 0.30, P less than 0.03), the plasma norepinephrine concentration (r = -0.30, P less than 0.05), the plasma epinephrine concentration (r = -0.49, P less than 0.001), and the pupillary latency period (r = 0.39, P less than 0.01). Each of these variables reflects the activity of the sympathetic nervous system or parasympathetic nervous system or both. Depressions in sympathetic and parasympathetic activity were significantly but weakly associated with increasing percentages of body fat. These associations indicate that in obese persons, autonomic changes, though not necessarily causal, involve several organ systems. We suggest that autonomic alterations are important in human obesity, as they are in animal obesity. A disordered homeostatic mechanism may promote excessive storage of energy by decreasing sympathetic activity, while defending against weight gain by decreasing parasympathetic activity. The use of autonomic profiles holds promise for classifying human obesity and identifying obese patients at increased risk for various disorders.

Adipose Tissue↗
PubMed1987

Multicenter comparison of the nifedipine gastrointestinal therapeutic system and long-acting propranolol in patients with mild to moderate systemic hypertension receiving diuretics. A preliminary experience.

The efficacy and safety of nifedipine in a gastrointestinal therapeutic system (GITS) push-pull osmotic pump formulation was compared with long-acting propranolol in 49 patients with mild to moderate hypertension already receiving diuretics. Using a two-week placebo run-in, double-blind study design, patients were randomly assigned to receive nifedipine GITS (n = 24) in doses of 30 mg, 60 mg, or 90 mg once daily; or long-acting propranolol (n = 25) in doses of 80, 160, or 240 mg once daily. Previous diuretic therapy was continued. Sitting and five-minute standing blood pressure and heart rate measurements were made 24 hours after dosing. At the endpoint of treatment, both nifedipine GITS and sustained-release propranolol reduced blood pressure compared with placebo (p less than 0.001) in the sitting and standing positions. Nifedipine GITS was more effective in lowering standing systolic blood pressure than was propranolol (p less than 0.02). Propranolol caused a greater reduction in resting heart rate than did nifedipine GITS (p less than 0.003). Both drugs were well tolerated. Nifedipine GITS is an effective and safe once-daily drug for use in patients with hypertension who are already receiving diuretics, may be more effective than sustained-release propranolol, and may be better tolerated than conventional nifedipine capsules.

Adult↗
PubMed1987

Regulation of alpha 2-adrenoceptor density in normotensive and hypertensive man.

We examined normotensive and hypertensive subjects in order to determine whether changes in platelet alpha 2-adrenoceptor density following alterations in plasma noradrenaline are related to changes in noradrenaline (NA) reactivity. Noradrenaline reactivity, plasma NA, alpha 2-adrenoceptor density, and adenylate cyclase activity were measured before and after a 24-h infusion of NA at a subpressor dose (0.02 micrograms/kg per min, n = 13), and also after application of drugs known to increase (nifedipine and furosemide) or decrease (clonidine) plasma NA. Measurements were obtained 60 min after nifedipine (20 mg in a single dose, n = 13), after 3 weeks on furosemide (30 mg twice a day, n = 8) and after 1 week on clonidine (150 micrograms three times a day, n = 5). Infusion of NA decreased alpha 2-adrenoceptor density (P less than 0.01) and NA reactivity (P less than 0.05). Nifedipine decreased alpha 2-adrenoceptor density and NA reactivity (P less than 0.01 for both) in patients with essential hypertension. The alterations in alpha 2-adrenoceptor densities were paralleled by a decreased adrenaline-induced inhibition of adenylate cyclase activity (P less than 0.01). Furosemide decreased alpha 2-adrenoceptor density (P less than 0.01), the fraction of high-affinity binding sites (P less than 0.01) and NA reactivity (P less than 0.05) in normotensive subjects. Following clonidine all three parameters, alpha 2-adrenoceptor density, the fraction of high affinity sites and NA reactivity, increased (P less than 0.05 for each).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1980

Improved nonoperative diagnosis of the solitary 'cold' thyroid nodule. Surgical selection based on risk factors and three months of suppression.

We assessed the cancer-predictive value of a nonoperative, two-stage prospective selection of solitary, cold, solid thyroid nodules that can be employed by the primary clinician. One hundred eighteen patients completed the protocol, all without adverse effect. The first stage identified for direct surgery 30 patients with a history of exposure to irradiation during youth, age under 20 years, recent growth of a hard nodule or lymphadenopathy, revealing 15 cancers and ten adenomas. In the second stage, the remaining 83 patients were given liothyronine for three months. Twenty-six nodules were excised because they failed to shrink 50% in diameter, disclosing five cancers and 19 adenomas. There were no cancers among 14 nodules excised for other reasons. Selection for surgery on the basis of clinical evaluation and risk factors alone can identify most of the cancers and lack of response to suppression a few more.

Humans↗
PubMed1979

Prostaglandin E inhibition of T-lymphocyte colony formation: a possible mechanism of monocyte modulation of clonal expansion.

Prostaglandin and monocyte modulation of a T-lymphocyte cell capable of undergoing clonal expansion was studied. Circulating human mononuclear cells were isolated by density centrifugation. After 24 h in culture with phytohemagglutinin present, the cells were mixed with 0.3% agar and overlayed onto a 0.5% agar layer that contained media and phytohemagglutinin. At day 6, colonies that contained greater than 50 cells were counted. These colonies represented clonal prolifertion of a phytohemagglutinin-responsive T-lymphocyte precursor. This responder cell accounted for less than 0.3% of the starting cell population. Colonies were comprised of cells which, when isolated, formed E rosettes. These colony cells could be shown to have helper or suppressor function as measured by their ability to promote or inhibit immunoglobulin synthesis. By these latter criteria the colony cells were considered to be mature T lymphocytes. The addition of prostaglandin E to the cultures demonstrated a linear, r = 0.82, dose-dependent inhibition of colony formation with a 50% point of inhibition (I50) = 0.18 muM. Low numbers of normal monocytes when added to the cultures mimicked the effect of synthetic prostaglandin E2. A highly significant correlation could be shown for endogenous prostaglandin E levels and colony counts. It appears that monocytes through their synthesis of prostaglandin E2 can restrict the clonal expansion of a circulating T-lymphocyte precursor.

Adult↗
PubMed1977

Diabetes insipidus following cardiorespiratory arrest.

Diabetes insipidus following cardiac arrest and hypoxemic encephalopathy occurred in two patients. In both, severe hypoxemic brain damage was followed within three days by clinical and laboratory features of diabetes insipidus, which were corrected by administration of exogenous vasopressin. Hypothalamic injury resulting in diabetes insipidus should be considered in the differential diagnosis of polyuria and dehydration occurring in critically ill patients who have suffered cardiorespiratory arrest.

Adult↗
PubMed1975

The jumping mechanism of Xenopsylla cheopis. I. Exoskeletal structures and musculature.

The jumping apparatus of the flea, which includes highly modified direct and indirect flight muscles, is described: attention is drawn to the various specializations of the exoskeleton which stiffen the thorax and also provide the 'click' mechanism triggering take-off. A finger-like invagination of tall cells within the cavity of the developing pleural arch of the pharate adult secretes the resilin pad. This is illustrated with coloured photographs. It is suggested that winglessness of a Mecopteran-like ancestor pre-adapted fleas to a parasitic life-style, and that a jumping mode of progression was a primitive feature of the whole Order. Scattered throughout the Siphonaptera today are species which have secondarily lost the pleural arch and with it the power to execute large jumps. These are usually found among fleas parasitizing mammals inhabiting caves, subterranean burrows and runs, high aerial nests and snow or ice-bound habitats. Large pleural arches are associated with fleas infesting large mobile hosts.

Animals↗
PubMed1975

The jumping mechanism of Xenopsylla cheopis. III. Execution of the jump and activity.

The flea's hind legs are the chief source of jumping power, but in species which execute large jumps, take-off is accelerated by elastic energy released from a resilin pad (homologous with the wing hinge ligaments of flying insects) situated in the pleural arch. A central click mechanism, operated by a rapid twitch of the trochanteral depressor (the starter muscle), synchronizes the separate sources of energy which power the jump. Ciné photos confirm the morphological evidence that the flea takes off from the trochanters, not the tarsi. The loss of wings, associated with lateral compression of the body and the shortening of the pleural ridge (which thus lowers the position of the pleural arch) together with modifications of the direct and indirect flight muscles, are some of the main morphological features associated with the change from a flying to a saltatorial mode of progression. The flea's take-off basically resembles that of other Panorpoid insects (Diptera, Mecoptera, etc.). The release of elastic energy from the pleural arch is a system by which the force used to move the wings of flying insects is rapidly fed back into the legs and adds power to the jump.

Animals↗