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Biomedical subjects

S C Smith

Publications and source records attributed to S C Smith.

At least 271 records · Page 15Linked to original sources
PubMed1978

Serum lipoprotein profiles of young atherosclerosis-susceptible White Carneau and atherosclerosis-resistant Show Racer pigeons.

1. Newly-hatched atherosclerosis-susceptible White Carneau and atherosclerosis-resistant Show Racer pigeons (Columba livia) had significantly lower (P less than 0.01) alpha/beta serum lipoprotein ratios than 6-week, 3-month, or 6-month old pigeons of the corresponding breed, as determined by densitometric analysis of polyacrylamide disc gel electrophoretic profiles. 2. Differences in alpha/beta serum lipoprotein ratios were not observed between the two breeds at any age studied.

Aging↗
PubMed1978

Effects of 6-hydroxydopamine lesions of the nucleus accumbens septi and olfactory tubercle on feeding, locomotor activity, and amphetamine anorexia in the rat.

Bilateral 6-hydroxydopamine lesions of the nucleus accumbens septi (NAS) and olfactory tubercle (OT) caused enhanced intake of wet mash in 23-hr-food-deprived rats tested in photocell activity cages during restricted 30-min sessions. This mild hyperphagia was accompanied by a significant hypoactivity in the group with NAS/OT lesions. No hyperphagia was observed during a prolonged 120-min test session or in free-feeding tests conducted in the home cage. Anorexia induced by d-amphetamine (.5 and 1.5 mg/kg) was unaltered by the lesion, although the locomotor stimulant action of the drug was attenuated. A second experiment showed that the NAS/OT lesion also enhanced food intake in the photocell cages during 30-min sessions with dry food pellets but that food-associated drinking was concomitantly reduced. The results are consistent with the hypothesis that the behavioral changes caused by mesolimbic neuron destruction result in part from an inability to switch from one behavioral activity to another.

Anorexia↗
PubMed1978

Relationship between Chloroplast Membrane Fatty Acid Composition and Photosynthetic Response to a Chilling Temperature in Four Alfalfa Cultivars.

The photosynthetic responses of four alfalfa (Medicago sativa L.) cultivars to 10 and 22 C air temperatures were examined and the relationship between the photosynthetic response at 10 C and the fatty acid composition of the chloroplast membranes was determined. Chilling-resistant cultivars exhibited moderate reductions in photosynthesis at 10 C, compared to 22 C, and contained a significantly greater percentage of polyunsaturated fatty acids in the chloroplast membrane and a greater double bond index than the chilling-sensitive cultivars. The chilling-sensitive cultivars exhibited severe reductions in photosynthesis at 10 C, compared to 22 C. The reduction in photosynthesis at 10 C is shown to be negatively correlated (r = -0.94) with the double bond index of the chloroplast membranes of the cultivars observed.The results support the hypothesis that reduced photosynthesis due to chilling temperatures is influenced by the unsaturated fatty acid composition of the chloroplast membrane which affect temperature-induced phase changes in chloroplast membrane lipids.

Journal Article↗
PubMed1977

Heparitin sulfates (heparan sulfates) of atherosclerosis-susceptible and atherosclerosis-resistant pigeon aortas.

Electrophoretic mobilities of heparitin sulfates (HS) from the thoracic aorta and the celiac bifurcation of atherosclerosis-susceptible White Carneau and atherosclerosis-resistant Show Racer pigeons at four ages were examined. Atherosclerosis-susceptible White Carneau aortas contain, in addition to their normal HS component, a variant type of HS (HS') in pre, early- and moderately-atherosclerotic celiac foci which is not found in the thoracic regions of either breed or in Show Racer celiac foci at any age. These findings are interpreted to suggest a role of HS' in the pathogenesis of atherosclerosis and to propose an explanation for atherosclerotic susceptibility and resistance in pigeons.

Age Factors↗
PubMed1976

Determination of background serum density for lipoprotein ultracentrifugation.

It is necessary to know the density of serum exclusive of its macromolecules (background density) prior to density adjustment with solid potassium bromide for ultra-centrifugal separation of lipoprotein fractions. To evaluate this, we compared the densities of the corresponding ultrafiltrates or dialysates of both human and equine sera produced by ultrafiltration and equilibrium dialysis method for macromolecule removal. Excellent correlation is found between background densities determined following ultrafiltration or equilibrium dialysis. These data validate the use of ultrafiltration as a simple, direct method for determination of background serum densities but reveal equilibrium dialysis to be more time consuming and less precise. Using ultrafiltration, we find the background density for equine serum to be 1.004 g/ml, and initial investigation suggests this value may be altered by freezing, prolonged refrigeration (3 months), or heating to inactivate lecithin: cholesterol acyltransferase.

Animals↗
PubMed1976

Bronchoconstriction and pulmonary hypertension during abortion induced by 15-methyl-prostaglandin F2alpha.

Patients have experienced severe breathlessness during second trimester abortion initiated by the intramuscular injection of 15-methyl-prostaglandin F2alpha (15-me-PGF2alpha). In four healthy women given 400 mug of 15-me-PGF2alpha to induce abortion, pulmonary function tests showed reductions in arterial oxygen tension, maximum expired air flow and vital capacity. Residual lung volume and the slope of phase III of the closing volume curves increased.

Abortion, Induced↗
PubMed1976

Computerized tomography using a modified orthogonal tangent correction algorithm.

A modified orthogonal tangent correction algorithm is presented for computerized tomography. The algorithm uses four X-rays scans spaced 45 degrees apart, to reconstruct a transverse axial image. The reconstruction procedure is interative in which image matrix elements are corrected by alternately matching the two sets of orthogonal scan data. The algorithm has been applied to phantom data as well as to video recorded fluoroscopic data.

Humans↗
PubMed1976

Yolk lipids of developing atherosclerosis susceptible White Carneau and atherosclerosis resistant Show Racer pigeon embryos.

The lipid composition of yolks of developing embryonic atherosclerosis-susceptible White Carneau (WC) and -resistant Show Racer (SR) pigeons was analyzed to determine whether embryonic nutrition might be a factor in the difference in susceptibility to aortic atherosclerosis. The yolks of 1-day and 18-day old embryos were analyzed, and the amounts of phospholipid, sterol, non-esterified fatty acid, triglyceride, cholesteryl ester, and hydrocarbon were determined. On the first day of development in both breeds, triglycerides composed 80% of the total lipid content of the yolk; phospholipids, cholesteryl ester, sterols and non-esterified fatty acids comprised the rest. There was no difference between breeds in the amount of lipid in each class or in the total lipid. Therefore, the initial lipid diet of these embryos is not a factor in development of the disease. Examination of the yolk just prior to hatching, revealed that in both breeds there was a significant decrease in total yolk lipids, but unequal utilization of lipid constitutents between breeds. Significantly higher amounts of phospholipids remained in the yolk of the WC pigeons. During embryogenesis, the SR pigeons consumed significantly more of each lipid than the atherosclerosis-susceptible breed. This may indicate that there is a difference between the two breeds in lipid metabolism.

Animals↗
PubMed1975

Maximal treadmill exercise testing in the management of the post-myocardial infarction patient.

Treadmill exercise tests were performed on 32 active duty military personnel 9 to 11 months after acute myocardial infarction to enable more objective selection of candidates for return to military service. Treadmill exercise tests were terminated at heart rates averaging 92 percent maximal predicted rate for age, or when chest discomfort with ischemic ECG changes occurred. The incidence of lipid abnormalities, hypertension, and other coronary risk factors did not differ among the groups. However, treadmill exercise tests appeared to identify a high risk group. Treadmill exercise testing in young postmyocardial infarction patients suggests that those with ischemic responses are at high risk of subsequent cardiac complications. Early surgery in this group may be warranted. The more frequently encountered negative response appears to be associated with a benign clinical course and better immediate prognosis.

Acute Disease↗
PubMed1975

Equine serum lipids: serum lipids and glucose in Morgan and Thoroughbred horses and Shetland ponies.

Concentrations of serum phospholipids, triglycerides, total cholesterol, nonesterified fatty acids, and glucose were determined for 9 months (September, 1972, to May, 1973) in 19 fasting horses and ponies (8 Morgan horses, 7 Thoroughbred horses, and 4 Shetland Ponies). Morgan horses had higher concentrations of total lipid than did Thoroughbreds, although the relative proportions of each type of lipid were similar in the 2 breeds. Shetland Ponies had higher nonesterified fatty acid and lower glucose concentrations than did either breed of horse. In both breeds of horses, concentrations of serum triglycerides in the cold months (December to March) were lower than those in the warm months. In the Shetland Pony, there was no seasonal variation in triglycerides, but a significant increase was seen in concentration of nonesterified fatty acids in the cold months. The significance of these findings is discussed.

Animals↗
PubMed1975

Equine serum lipids: serum lipoprotein profiles of Morgan and Thoroughbred horses.

The serum of lipoproteins of 10 Morgan and 8 Thoroughbred horses were examined by 2 methods of polyacrylamide gel electrophoresis. A significant breed difference in the beta-lipoprotein to alpha-lipoprotein ratio was seen in gradient slab electrophoresis. A breed difference in the number of peaks, but no difference in beta-lipoprotein to alpha-lipoprotein ratio, was found in disc gel electrophoresis. These results have been correlated to indicate differences in charge of alpha-lipoprotein components and in size of beta-lipoprotein components between these 2 breeds of horses.

Animals↗