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Biomedical subjects

F Clemente

Publications and source records attributed to F Clemente.

At least 37 records · Page 2Linked to original sources
PubMed1977

[Spontaneous phospholipase A activity of rat pancreatic homogenates].

Rat pancreas presents a spontaneous phospholipase A activity which appears before trypsin activation at optimal pH 6.5. The responsible enzyme is independent of pancreatic prophospholipase A, as can be seen through experiments done in the presence of trypsin inhibitors. On the other hand, this enzyme is distinct from excretory phospholipase which is more active and whose optimal pH is 8.8. Thermostability and insensibility of spontaneously active phospholipase A to DFP differentiate it from lipase, carboxyl-esterhydrolase and lysophospholipase, respectively.

Animals↗
PubMed1976

Support for the medical profession among the aged.

National survey data are utilized to delineate areas of confidence among the aged in the medical profession. Four key specifying variables were used in the analysis-race, sex, socioeconomic status, and size of community. Findings indicate that confidence in medical leaders is lowest among that group which in past studies has been found to visit the doctor most often: the elderly of low socioeconomic status. This finding suggests that improvement in the medical care received by the aged could be an important first step in restoring the elderly's confidence in medical leaders.

Adolescent↗
PubMed1975

Calcium and pancreatic secretion. I. Subcellular distribution of calcium and magnesium in the exocrine pancreas of the guinea pig.

The distribution of calcium and magnesium has been studied in the acinar cells of the pancreas of the guinea pig. Most of the magnesium was found to be associated with the rough microsomes (probably bound to the ribosomes) and with the postmicrosomal supernate. In contrast, calcium was distributed among all the particulate fractions, primarily the mitochondria, microsomes (especially smooth surfaced), zymogen granules, and the plasmalemma, and was low in the postmicrosomal supernate. Most of the calcium recovered in the particulate fractions was found to be membrane bound. The highest concentrations were found in the membranes of the zymogen granules and in the plasmalemma. By means of control experiments using -45Ca as the tracer, it was established that a considerable redistribution of calcium occurs during homogenization and cell fractionation. At least some of the resulting artifacts were estimated quantitatively and the data were corrected accordingly. The biochemical results were confirmed with the cytochemical antimonate technique carried out on the tissue as well as on isolated fractions. The role of calcium associated with the zymogen granules and with their limiting membranes is discussed in relation to the architecture of the granule and to the functionality of the pancreatic juice.

Animals↗
PubMed1975

The participation of the black aged in voluntary associations.

Racial differences in membership in and attendance of voluntary associations were analyzed for comparable samples of 753 black and 260 white residents of Philadelphia age 65 and over. A hypothesis suggesing aged blacks have higher rates of participation than aged whites was derived from the literature and tested by regression analysis. Potentially confounding variables, e.g., health and socioeconomic status, were entered into the regression equation as controls. The results of the regression analysis indicated the black aged belonged to more associations than the white aged and had higher rates of attendance. Examination of findings previously reported by Kent and Hirsch (1972) indicates part of the difference is due to the greater participation of aged blacks in church-related groups. Implications of the findings are briefly discussed.

Black or African American↗
PubMed1975

Calcium and pancreatic secretion-dynamics of subcellur calcium pools in resting and stimulated acinar cells.

1 Pulse-chase experiments were carried out on pancreatic tissue lobules incubated in vitro, with 45Ca as the tracer, in order to shed some light on the functional significance of the calcium pools associated with the various cell organelles of the acinar cell, especially in relation to stimulus-secretion coupling. 2 The kinetics of tracer uptake and release which were observed in the intact lobules suggest the existence of a number of intracellular pools, whose rate of exchange is slower than that across teh plasmalemma. 3 The various subcellular fractions accumulate the tracer in different amounts: some (rough microsomes and postmicrosomal supernatant) showed little radioactivity and some (smooth microsomes and zymogen granule membranes) were heavily labelled; mitochondria and zymogen granules showed intermediate values. 4 The fractions are heterogeneous also in relation to the time course of uptake and release of the tracer: in rough and smooth microsomes and, especially, in the postmicrosomal supernatant both rates were fast; zymogen granules and zymogen granule membranes showed slow rates of uptake and little release during chase; intermediate rates were found in mitochondria. 5 In agreement with previous findings we observed that in 45Ca preloaded lobules, stimulation of secretion (brought about by the secretagogue polypeptide caerulein) results in an increase of the tracer release which seems to be due primarily to the rise of the intracellular concentration of free Ca2+ and to the consequent increase of the transmembrane Ca2+ efflux. Among the cell fractions isolated from stimulated lobules only the mitochondria exhibited a significantly lower 45Ca level relative to the unstimulated controls. 6 It is concluded that, of the organelle-bound calcium pools, that associated with the mitochondria might be involved in the regulation of the calcium-dependent functions, including stimulus-secretion coupling; the calcium associated with the zymogen granule content probably has a role in the architecture of the organelle and in the functionality of the pancreatic juice, while the calcium bound to the membrane of the granules might be concerned with the regulation of its permeability properties.

Animals↗
PubMed1975

Secretion of calcium in pancreatic juice.

1. The orgin of the calcium secreted by the pancreas has been investigated in vivo in the guinea-pig by a study carried out in parallel (a) in the juice secreted in response to the injection of either secretin or caerulein and (b) in the pancreatic tissue and in cell fractions isolated thereform. 2. In agreement with previous findings we observed that the concentration of calcium is low in the secretin-stimulated and high in the caerulein-stimulated juice. In the latter calcium and protein are proportional (cal0 n-mole:mg). 3. After I.V. injection of 45Ca the radioactivity decreases rapidly and quasi-exponentially in the blood plasma. A roughly parallel time course is found in the secretin-stimulated juice: the evolution of the juice: plasma radioactivity ratio resembles that observed with the extraceullar space marker [3H]D-sorbitol. In contrast, the time course of 45Ca in plasma and caerulein-stimulated juice are not proportional: the high levels characteristic of this juice are reached several minutes after the injection and maintained thereafter. This increase is followed ca. 50 min later by the appearance of the newly synthesized [3H]L-leucine-labelled proteins. 4. The pancreatic tissue is rich in calcium which is localized primarily in zymogen granules (Ca.36 n-mole:mg protein) and mitochondria; the soluble cytoplasm is low in calcium. 5. The injected 45Ca accumulates in zymogen granules faster than [3H]L-leucine-labelled proteins. The 45Ca:protein ratio of these organelles is considerably lower than that of the caerulein-stimulated juice. 6. It is concluded (a) that calcium is secreted in to the pancreatic juice in two fractions, one (possibly released by simple diffusion) associated with the electrolyte component, the other with protein of the juice, (b) that zymogen granules are the major, but not the only source of the latter fraction, and (c) that the zymogen granule-associated calcium joins the exportable proteins some time after their synthesis, possibly in the Golgi complex and/or in the condensing vacuoles.

Animals↗
PubMed1971

A comparison of alcoholic pancreatitis in rat and man.

Acute ethanol intoxication was studied in 38 Wistar rats, 18 on a balanced diet and 20 on a high fat diet, fed by gavage on 47% ethanol in a dosage of from 3 to 12 g/kg body weight daily for periods ranging from three to 16 days. No macroscopic changes in pancreas or liver were found in any of these animals. Histological changes (venous congestion of the pancreas, the liver, and the kidneys) were found in rats given 4 g or more per kilogram. The only difference between the findings in rats given a balanced diet and those given a high fat diet was the development of fatty livers in the latter group. Chronic ethanol intoxication was studied in 45 Wistar rats, on a balanced diet, which were given 20% ethanol freely for 20 to 30 months. More than half the animals developed pancreatic lesions very similar to those of human chronic pancreatitis. The pathological changes, in foci surrounded by normal pancreatic tissue, were a reduction in acini, duct multiplication (probably by neogenesis), protein plugs, sometimes calcified in the ducts and sclerosis. Samples of pancreatic juice from four animals exposed to ethanol contained significantly higher protein concentrations than samples taken from two control animals. Protein precipitates appeared spontaneously in the pancreatic juice of the animals exposed to ethanol, but not in that of the controls. These findings are very similar to those in alcoholic pancreatitis in man, which has thus been reproduced for the first time in experimental animals. Beta-cell adenomata of the islets of Langerhans were observed in four of the rats exposed to ethanol.

Acute Disease↗