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Biomedical subjects

M I Friedman

Publications and source records attributed to M I Friedman.

At least 127 records · Page 7Linked to original sources
PubMed1978

Hyperphagia in rats with experimental diabetes mellitus: a response to a decreased supply of utilizable fuels.

Alloxan-diabetic rats were hyperphagic when fed diets containing little fat, but they ate normal amounts of food when given diets rich in fat. Normal rats increased food intake to the same degree when the caloric density of their diet was decreased by reducing the content of fats or carbohydrates in isocaloric amounts. Diabetic rats did not respond substantially to changes in caloric density of their diet which were produced by altering the content of dietary carbohydrates, but they systematically increased food intake as the amount of fat in their diet was reduced. Diabetic rats ate normal amounts of a high-fat diet despite continued loss of nutrients in urine and persisting impairments in glucose utilization, fat storage, and liver glycogen deposition. These findings suggest that hyperphagia in experimental diabetes mellitus is a compensatory response to a lack of utiliziable fat fuels rather than the result of a metabolic disturbance per se.

Animals↗
PubMed1977

Caffeine restores feeding response to 2-deoxy-D-glucose in 6-hydroxydopamine-treated rats.

A large portion of the central catecholaminergic nerve terminals of the rat are destroyed by administering 6-hydroxydopamine (6-HDA) via the cerebrospinal fluid. Animals lesioned in this way often appear normal, yet show many subtle behavioural abnormalities. We have been examining one example of this phenomenon, the failure of 6-HDA-lesioned rats to increase food intake when given a systemic injection of 2-deoxy-D-glucose (2-DG) (refs 5, 6). This glucose analogue seems to elicit feeding in intact rats due to its inhibition of glycolysis in cerebral chemoreceptor cells. We have proposed that lesioned animals do not eat because of an insufficient central catecholaminergic response to the severe decrease in glucose utilisation induced by 2-DG (ref. 10). If so, then pretreatments which serve to augment this neurochemical response might be expected to reinstate behavioural function. Consistent with this hypothesis, very large increases in telencephalic tyrosine hydroxylase activity in 6-HDA-lesioned animals, which occur following chronic insulin treatment, are associated with the restoration of 2-DG-induced feeding. Many of the physiological effects of catecholamines in the sympathetic nervous system seem to be mediated by an increase in the cyclic AMP concentration of the target cells. Methylxanthenes, such as caffeine and theophylline, inhibit phosphodiesterase, prevent cyclic AMP degradation, and thereby potentiate the catecholamine-stimulated rise in cyclic nucleotide. They also enhance many of the behavioural and physiological effects of catecholamines, presumably by the same mechanism. We therefore sought to determine whether the acute administration of those sympathomimetic agents, in intact and 6-HDA-lesioned rats, also would potentiate 2-DG-induced feeding, a behaviour that seems to be mediated, in part, by central catecholaminergic neurons. We report that caffeine restores the 2-DG-induced feeding response.

Animals↗
PubMed1977

Homeostasis during hypoglycemia: central control of adrenal secretion and peripheral control of feeding.

Intravenous infusions of manose or B-hydroxybutyrate, metabolic fuels which can be oxidized by brain, abolished adrenal discharge of epinephrine in rats during insulin-induced hypoglycemia, whereas infusion of fructose, a sugar which does not cross the blood-brain barrier, did not. In contrast, increased feeding behavior during hypoglycemia was prevented both by the sugars and by B-hydroxybutyrate. Thus, while the sympathetic response during marked hypoglycemia may have been initiated by alterations in cerebal metabolism, the feeding response evidently was not, and a decrease in the utilization of glucose per se does not appear to be the critical stimulus in either case.

Animals↗
PubMed1977

Insulin-induced hyperphagia in alloxan-diabetic rats fed a high-fat diet.

Alloxan-diabetic rats fed a standard, low-fat diet lost body weight and were hyperphagic; those fed a high-fat diet lost comparable amounts of weight, but did not overeat compared to normal animals. When given injections of protamine-zinc insulin, all diabetic rats gained weight; however, while those fed the low-fat reduced food intake from elevated levels, diabetics fed the high-fat diet became hyperphagic. Diabetic rats maintained on a high-fat diet increased food intake during long-term insulin treatment sooner and to a greater extent than normal controls. These findings are interpreted in light of the effects of insulin on storage and supply of metabolic fuels.

Animals↗
PubMed1977

Radiocardiography in clinical cardiology.

Quantitative radiocardiography provides a variety of noninvasive measurements of value in cardiology. A gamma camera and computer processing are required for most of these measurements. The advantages of ease, economy, and safety of these procedures are, in part, offset by the complexity of as yet unstandaridized methods and incomplete validation of results. The expansion of these techniques will inevitably be rapid. Their careful performance requires, for the moment, a major and perhaps dedicated effort by at least one member of the professional team, if the pitfalls that lead to unrecognized error are to be avoided. We may anticipate more automated and reliable results with increased experience and validation.

Heart Aneurysm↗
PubMed1975

Glucoregulatory feeding by rats after intraventricular 6-hydroxydopamine or lateral hypothalamic lesions.

Rats given intravenricular injections of 6-hydroxydopamine or bilateral electrolytic lesions of the lateral hypothalamus do not show the normal increase in food intake in response to large decreases in glucose utilization or exposure to severe cold stress. However, they will eat more during chronic glucoprivation that is less intense, or during exposure to more moderate cold stress. Thus, the feeding deficits of these lesioned rats may not reflect an inability to respond to certain qualitatively different stimuli, but rather an inability to respond to quantitatively different intensities of the same stimulus.

Animals↗
PubMedDate not supplied

Compensatory hyperphagia after fasting tracks recovery of liver energy status.

Studies using metabolic inhibitors suggest that a reduction in hepatic ATP generates a stimulus that triggers feeding behavior. To investigate the relationship between changes in liver ATP and food intake under physiological conditions, we assessed changes in feeding behavior and liver adenine nucleotides during refeeding after 24 h of food deprivation. Deprived rats consumed 14 g of food in the first 3 h of refeeding; the rate of consumption declined markedly thereafter for the next 9 h, but remained higher than that seen in nonfasted rats. Fasting produced substantial reductions in ATP, ATP/ADP, and phosphorylation potential relative to fed levels. Refeeding restored liver ATP by 6 h, whereas ATP/ADP and phosphorylation potential did not fully recover until 12 h of refeeding. Restricting food intake during refeeding limited recovery of liver energy status. These results show that liver energy production recovers slowly during refeeding with a time course that parallels the compensatory change in eating behavior. These findings raise the possibility that changes in hepatic energy status play a role in satiation as well as in hunger.

Adenosine Diphosphate↗
PubMedDate not supplied

Do patient data ever exceed the partial volume limit in gated SPECT studies?

BACKGROUND: Some single photon emission computed tomography (SPECT) methods to detect percent myocardial wall thickening (%WT) assume a linear relationship to changes in maximum myocardial counts, predicated on myocardial walls never exceeding the SPECT camera's partial volume limit. Recent studies have challenged such assumptions, reporting that systolic count changes underestimate wall thickening as measured by echocardiography and magnetic resonance imaging. METHODS AND RESULTS: To test whether clinical data ever are observed to exceed the partial volume limit, we examined gated tomograms of 75 patients selected at random and of an additional 25 patients known to have hypertension with electrocardiographic evidence of left ventricular hypertrophy. Image transformations were performed such that for every cinematic frame, radial counts at every angle were automatically normalized to the same maximum count. If no patient's myocardium ever exceeded the partial volume limit, thickness quantified from transformed images would always be the same throughout the cardiac cycle and would just correspond to the camera's line spread function. Thickness was measured by Gaussian fitting of transformed myocardial counts in the epicardial direction only to exclude cavitary count contamination. % WT was computed from thickness differences from diastole to systole. % WT values were assessed from clinical data at lateral, inferior, septal, anterior, and apical territories. Resulting %WT distributions were tested against the null hypothesis of %WT = 0 by the Z-test. Although some distributions were not actually Gaussian, the maximum mean %WT was only +3% +/-5% for the septal wall, in agreement with an observer's impressions of no detectable wall thickening. Thus mean %WT values were trivial compared with expected physiologic normal values of 30% to 50%. CONCLUSION: No convincing evidence was found of thickness above the partial volume limit in this large sample of 75 normotensive and 25 hypertensive patients. Therefore it is likely that relations between myocardial count increases and wall thickening are similar throughout the cardiac cycle, even in patients with left ventricular hypertrophy.

Adult↗
PubMedDate not supplied

Diagnosing boredom and confusion.

An interview schedule to determine whether individuals could be diagnosed psychologically as being in a bored, confused, or adaptive state of mind was constructed and tested. Boredom and confusion were viewed as two distinct maladaptive states of mind. Objectivity, reliability, and validity were demonstrated for the interview schedule. The schedule was effective in diagnosing maladaptive and adaptive states of mind in outpatients who sought help at a family practice clinic and in detecting changes from maladaptive states to an adaptive state of mind after four weeks of psychological treatment.

Adaptation, Psychological↗
PubMedDate not supplied

Parenteral nutrition and oral intake: effect of glucose and fat infusions.

The effect of intravenous nutrition on voluntary oral intake was studied in healthy male volunteers. Subjects were confined to the Surgical Metabolic Unit for the 17 to 19 day study and were restricted to commercial liquid diet. Each study consisted of three consecutive phases: (1) Ringer's lactate (RL), (2) peripheral parenteral nutrition (PPN) administered for 5 or 6 days as a combination of glucose (caloric load equal to 34% resting energy expenditure, REE), fat (34% REE), and amino acids (17% REE) or a single nutrient infusion of glucose (68% REE), fat (68% REE), glucose (34% REE), or fat (34% REE), and (3) RL for the third period. When all three nutrients or glucose alone (68% REE) were given, subjects decreased daily voluntary food intake within 24 to 48 hr by an amount that closely compensated for the infused calories. Intake was reduced by only 20% to 40% of the infused calories when fat alone (68% REE) was given. There were no significant effects when the lower levels of glucose and fat were given. These data suggest the presence of a postabsorptive control of food intake in humans that is sensitive to the circulating supply of fuels.

Administration, Oral↗