Biomedical subjects

J Schmee

Publications and source records attributed to J Schmee.

30 records · Page 2Linked to original sources

PubMed1985

Endothelial and lesion cell growth patterns of early smooth-muscle cell atherosclerotic lesions in swine.

This study shows that the endothelial cell turnover over the early porcine atherosclerotic lesion is more or less uniform in distribution. This is contrary to the findings in White Carneau pigeons where the increased endothelial cell turnover has a zonal pattern, being much greater at the lesion edge. The difference in the endothelial cell pattern of turnover in the two lesions probably is a reflection of their different manner of development. The porcine abdominal aortic lesion is derived from naturally occurring preexisting collections of intimal smooth-muscle cells called intimal cell masses. After 90 days of a hyperlipidemic diet these lesions are composed predominantly of smooth-muscle cells, with very few monocytes. The White Carneau pigeon lesion develops from circulating monocytes that have been shown to adhere to the edge of the lesion.

Animals↗

PubMed1984

Population dynamics of arterial cells. XIV. Evidence for no significant G2 arrest of intimal and medial cells in young nonatherosclerotic swine.

In an earlier study of swine results from analysis of tritiated thymidine data by an "ancestor table" method suggested a substantial arrest of arterial cells in the G2 phase of the cell cycle. A later study with a cytofluorometric method gave contradictory results with no evidence for significant G2 arrest. On reexamination of the earlier data with the ancestor table method in the light of current knowledge, it was found that the fact that nuclei in the S and G2 phases prior to division are larger than those in G1 after division had not been taken into account. The main purpose of the current study was to find out whether the evidence for G2 arrest would entirely disappear if adjustments were made for differences in nuclear sizes before and after division. A baseline group sacrificed 2 hr after tritiated thymidine injection and two experimental groups (one fed hyperlipidemic diet and the other given cholesterol-free mash) sacrificed 47 hr after injection were studied. Using the ancestor table method it was found that virtually all labeled arterial cells divided in both groups; thus there is no evidence for G2 arrest. The data was also analyzed with a form of the "mean grain count halving" method and this also showed all labeled cells dividing.

Animals↗

PubMed1984

Hypo-atherogenic effect of dietary corn oil exceeds hypo-cholesterolemic effect in swine.

Three groups of young swine were fed semi-purified diets enriched in fat and cholesterol for 90 days. In one group 40% of calories were from butter; in another 40% were from corn oil; in a third group 20% were from corn oil. Mean serum cholesterol values were respectively 530, 458 and 400 mg/dl. Amounts of atherosclerosis in the abdominal aortas expressed as mean number of nuclear profiles per cross-section were respectively 1611, 734 and 585; expressed as mean lesion area per cross section 46.7, 21.4 and 19.4 mm2 X 10(2). All differences between the butter group and either of the two corn oil groups were statistically significant. We found that intimal response to the butter containing diet was significantly greater than to the corn oil containing diet for equivalent hypercholesterolemic response. We present detailed statistical validation of the disproportionately larger intimal response to butter containing diet. Furthermore, we suggest that estimates of comparative atherogenic risk of food fats based on response of serum cholesterol may mask important atherogenic differences.

Animals↗

PubMed1984

Quantification of intimal cell masses and atherosclerotic lesions in coronary arteries of control and hyperlipidemic swine.

In the current study of swine coronary arteries, we have attempted to quantify the coronary intimal cell masses (ICM) with regard to two aspects: (1) percentage of total arterial wall cells (intimal plus medial) that are in the intima, and (2) percentage of arterial wall area occupied by intima. We have studied 4 coronary sites: left main stem (LMS), proximal right (RCA), proximal left circumflex (LCX), and proximal left anterial descending (LAD). In mash-fed ('normal') swine we carried out the study at 3 ages: 2, 5 and 12 months. In addition, we have carried out a similar study in swine fed hyperlipidemic (HL) diets for 3 or approximately 10 months starting at 2 months of age. In the control swine we found approximately 6% of the arterial wall occupied by intima at 2 months of age with no significant increases by 12 months. There were no consistent significant differences among the 4 coronary artery sites with regard to percentage of wall occupied by intima. When the HL diet was fed, there were significant increases in the percentage of the arterial wall occupied by intima (now atherosclerotic lesion) by 3 months on diet and much larger increases by 10 months (up to 87% of wall occupied by intimal lesion) with extensive regions of lipid-rich, calcific, necrotic debris. After 3 months on HL diet the RCA lesions occupied significantly greater percentages of areas than the other 3 sites but this difference had disappeared by 10 months on the HL diet.

Animals↗

PubMed1983

Population dynamics of arterial cells during atherogenesis. XIII. Mitogenic and cytotoxic effects of a hyperlipidemic (HL) diet on cells in advanced lesions in the abdominal aortas of swine fed an HL diet for 270-345 days.

The abdominal aortas of five groups of young male Yorkshire swine were studied: (1) 0-day baseline group; (2) hyperlipidemic (HL) group with ballooning; (3) mash group with ballooning; (4) mash group without ballooning; and (5) HL group without ballooning. The last four groups were injected with [3H]thymidine at 270 days and sacrificed subsequently in subsets at intervals up to 75 days in order to study births and deaths (or loss by migration) among cells over the period 270-345 days. However, only in the HL-ballooned group were there enough swine for the isotopic data to be useful for most purposes. In the 0-day baseline group there were 6 +/- 2 X 10(6) cells in intimal cell masses (ICM); in the 270- to 345-day mash group without ballooning the number was 10 +/- 2 X 10(6), which is not a statistically significant increase over 0-day. This supports the hypothesis that in the normal state births and deaths (or loss by migration) among cells in ICM are nearly balanced at least up to 1 year of age. In the 270- to 345-day mash group with ballooning there were 61 +/- 12 X 10(6) cells in the ICM. Thus a single episode of deendothelialization results in tremendous hyperplasia of ICM. However, even the largest ICM (atherosclerotic lesion) in this group showed essentially no necrosis. In the 270- to 345-day HL group with ballooning there were 108 +/- 17 X 10(6) cells in the ICM turned atherosclerotic lesions. In addition an average of one-third of the lesion volume was occupied by lipid-rich, calcific necrotic debris. Thus the HL diet appears to have associated with it both mitogenic and cytotoxic influences on ICM cells. In the 270- to 345-day HL group not ballooned there were 130 +/- 30 X 10(6) lesion cells and lesions were somewhat more extensive and necrotic than in the HL-ballooned group, probably because the former group included by chance more hyperresponders (as regards serum cholesterol values) to the HL diet than the latter. Regardless of this, the data suggest that in this particular model of advanced atherosclerosis the balloon-injury stimulus to proliferation and the HL-diet stimulus are neither additive nor synergistic.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗

PubMed1983

Anti-proliferative effect of pyridinolcarbamate and of aspirin in the early stages of atherogenesis in swine.

When young swine are fed a suitable hyperlipidemic (HL) diet the number of cells in intimal cell masses (ICM) of large and medium-sized arteries begins to increase in number; by 90 days on the diet the cell increase is several-fold compared to no significant increase in cell numbers in ICM of mash-fed controls. The objective of the current study was to see if the cell increase associated with the HL diet could be reduced by pyridinolcarbamate or aspirin. Arteries studied were the abdominal aorta and the coronaries; time on HL diet was 90 days. Both drugs resulted in significant reductions in the increases in cells in ICM associated with the HL diet in both of the arterial beds that were studied. The reduction was most prominent in the abdominal aorta where the increase in ICM cells in the untreated HL diet-fed swine was from an average of 242 +/- 50 cells per cross-section in the mash-fed controls to 1925 +/- 556; in the pyridinolcarbamate-treated swine the increase was only to 641 +/- 214 and in the aspirin-treated group to 770 +/- 146.

Animals↗

PubMed1979

An examination of patient referral and discharge policies using a multiple objective semi-Markov decision process.

A model is developed for determining an appropriate policy for referral or discharge of patients from the different modes of care in a progressive patient care facility. The objectives of the model are to achieve a high probability that the average patient recovers and to provide care at a low cost. Previous results concerning multichain semi-Markov processes are used in conjunction with vector maximum in order to generate all nondominated solutions to the problem.

Decision Making↗

PubMed1977