Effects of milk consumption and deprivation on body fluids of suckling rats.
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Biomedical subjects
Publications and source records attributed to M I Friedman.
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Some of the available cardiovascular nuclear medicine methods are incompletely validated, and others are incompletely developed. They are, however, of very great potential in diagnostic cardiology, and in patient management. A new era of clinical research and acute care monitoring has been opened by serial, noninvasive, hemodynamic measurements of right ventricular as well as left ventricular function. Stress testing has become more specific, and should, with future developments, become more specific, and should, with future developments, become more sensitive, using radionuclide procedures. Serious quality control and validation questions concerning thallium stress testing must be addressed. Intracoronary injection of radiogases has great potential, although minimal present application. Emission computerized tomography will be an important research tool. Compartmental analysis modeling of first pass tracer injections has much to offer, but is not yet validated. Present growth rate of these procedures is very rapid. Fully developed, cardiovascular nuclear medicine may become the largest component of clinical nuclear medicine practice.
In this paper we critically review anatomic, electrophysiological, physiological, and behavioral evidence for neural receptors in the liver. Several lines of evidence suggest that the afferent innervation of the liver may be substantial, although few anatomic studies have directly addressed the question of an hepatic sensory supply. On the other hand, there is convincing functional evidence for a variety of hepatic sensory receptors. Hepatic osmo-, ion, and baroreceptors, sensitive to changes in the osmolarity and electrolyte concentrations in blood and to variations in portal venous pressure, modulate diuresis and natriuresis. Metabolic receptors, for which the adequate stimuli have not yet been specified, influence feeding behavior and gastric acid secretion in response to alterations in hepatic metabolism associated with changes in the supply of metabolic fuels. Directions for future research are suggested and general conclusions about the role of hepatic receptors in homeostasis are discussed.
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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.
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.
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.
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.
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