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Biomedical subjects

P Samuel

Publications and source records attributed to P Samuel.

At least 55 records · Page 3Linked to original sources
PubMed1987

Heterogeneity of cholesterol homeostasis in man. Response to changes in dietary fat quality and cholesterol quantity.

Studies were carried out to examine the effects of dietary fat and cholesterol on cholesterol homeostasis in man. 75 12-wk studies were carried out during intake of 35% of calories as either saturated or polyunsaturated fat, first low and then high in dietary cholesterol. Dietary fat and cholesterol intakes, plasma lipid and lipoprotein levels, cholesterol absorption and sterol synthesis in isolated blood mononuclear leukocytes were measured during each diet period. In 69% of the studies the subjects compensated for the increased cholesterol intake by decreasing cholesterol fractional absorption and/or endogenous cholesterol synthesis. When an increase in plasma cholesterol levels was observed there was a failure to suppress endogenous cholesterol synthesis. Plasma cholesterol levels were more sensitive to dietary fat quality than to cholesterol quantity. The results demonstrate that the responses to dietary cholesterol and fat are highly individualized and that most individuals have effective feedback control mechanisms.

Cells, Cultured↗
PubMed1986

Improvement of the lipid profile during long-term administration of pindolol and hydrochlorothiazide in patients with hypertension.

The effect of the combined administration of pindolol (10 or 20 mg daily) and hydrochlorothiazide (50 mg daily) on the serum lipid and lipoprotein levels of 34 hypertensive patients was investigated for 6 to 18.5 months (mean 13.3). Placebo control data were compared with the results obtained during treatment periods in each patient by paired t tests. Mean levels of high-density lipoprotein cholesterol increased by 17% (p less than 0.01), low-density lipoprotein cholesterol decreased by 4% (p less than 0.01) and the high-density lipoprotein: low-density lipoprotein cholesterol ratio increased by 28% (p less than 0.01). Total serum cholesterol, serum triglycerides and very low-density lipoprotein cholesterol showed no statistically significant changes from control values. These findings suggest that the long-term administration of this beta blocker combined with a diuretic results in serum lipid changes considered beneficial in the evaluation of risk factors for coronary artery disease.

Adult↗
PubMed1985

[Chiari's osteotomy in adults. Apropos of 72 cases].

The authors have performed 65 Chiari osteotomies in adults. The results have been studied with a follow-up ranging from one to 12 years. Details of the surgical technique are described. Fifty-three cases have had satisfactory results. Forty-five cases have a follow-up of more than 5 years and among these, 38 still have a very satisfactory result. It is concluded that Chiari osteotomy may stop the development of early arthrosis clinically as well as radiologically in more than two-thirds of dysplasias or subluxations in patients younger than 50 years. When there is associated femoral dysplasia it should be corrected either simultaneously or preceding the osteotomy.

Adult↗
PubMed1985

[Bilateral luxation of L5-S1. Apropos of a case reduced and fixed at the 120th day].

A case of pure anterior lumbosacral dislocation without fracture of the posterior arch has been seen by the authors. The patient was a woman who was six months pregnant at the time of injury. The dislocation was not recognised at first. Four months later, after delivery, function was poor. The displacement was reduced surgically and fixed by plates and screws using a posterior approach.

Adult↗
PubMed1983

Effects of gemfibrozil on serum lipids.

A two-part, multicenter study to assess the clinical efficacy, side effects, and safety of gemfibrozil in 427 patients over treatment durations of up to 13 months showed that this drug markedly reduces the level of serum triglycerides, while moderately lowering total serum cholesterol levels. The high-density lipoprotein cholesterol level was substantially increased, with concomitant decreases in low-density lipoprotein and very low-density lipoprotein cholesterol levels. The drug was generally well tolerated. However, a potential for increasing blood glucose levels was noted and careful monitoring during therapy is recommended.

Adult↗
PubMed1983

Treatment of familial hypercholesterolemia by portacaval anastomosis: effect on cholesterol metabolism and pool sizes.

Measurements of the key parameters of cholesterol homeostasis and the mass of the body pools of cholesterol were carried out in two patients with familial hypercholesterolemia (FH), one homozygote and one heterozygote, before and 28 and 18 months, respectively, after portacaval anastomosis (PCA). In both patients the procedure significantly reduced the plasma concentrations of total and low density lipoprotein cholesterol and the daily rate of whole body cholesterol and bile acid synthesis. In addition, PCA caused a net efflux of accumulated tissue cholesterol as demonstrated by reductions in the rapidly exchangeable and total exchangeable masses of body cholesterol. Shunt patency was verified by demonstration of increased bile acids in serum from fasting patients and from patients 2 hr after a meal and by increased plasma glucagon before and after arginine infusion. Other than a persistently increased level of serum alkaline phosphatase, liver function tests have fallen within the normal range in both patients; there has been no evidence of hepatic encephalopathy. In the homozygous patient there has also been a striking resolution in xanthoma size and distribution. These multiple effects on cholesterol homeostasis and pool sizes strongly suggest that PCA can reverse the progressive accumulation of cholesterol in body tissues of FH patients.

Bile Acids and Salts↗
PubMed1983

The role of diet in the etiology and treatment of atherosclerosis.

The role of various dietary constituents in the etiology of hyperlipidemia and cardiovascular disease is examined in light of currently available data from epidemiological and clinical studies. Recommendations regarding the dietary management of the hyperlipidemic patient at risk are presented and the advisability of generalized dietary guidelines for the public examined. The certainties, which are few, and the uncertainties, which are numerous, regarding the cause and effect relationship between diet, hyperlipidemia, and cardiovascular disease suggest that dietary intervention to treat the hyperlipidemic patient is a rational first step but that the generalization of this approach for the public may be premature.

Alcohol Drinking↗
PubMed1983

Differential absorption of exogenous and endogenous cholesterol in man.

Cholesterol absorption was measured in six patients by a triple-lumen intubation technique: 1) to determine whether isotopic exchange between radiolabeled lumenal cholesterol and unlabeled mucosal cholesterol occurs during cholesterol absorption measurements, and 2) to differentiate the rates of absorption of endogenous cholesterol ([1,2-3H]cholesterol marker given intravenously 6 weeks prior to the tests), exogenous cholesterol ([4-14C]cholesterol marker infused into the proximal duodenum), and total cholesterol mass (sitosterol marker incorporated in the infusion mixture). Measurements of endogenous cholesterol absorption during infusion of a cholesterol-free formula produced identical results whether calculated by the [1,2-3H]cholesterol marker (46.2 +/- 18.2%) or sitosterol marker (44.3 +/- 16.9%) in eight studies. When exogenous cholesterol was administered in liquid formula, its absorption was significantly lower than that of endogenous cholesterol in six out of nine experiments (endogenous = 46.4 +/- 15.4%; exogenous = 33.6 +/- 8.3%; total = 40.9 +/- 10.0%). When exogenous cholesterol was dissolved and administered in triglycerol monooleate, its absorption was higher than that of endogenous cholesterol in four of seven experiments (endogenous = 29.6 +/- 14.5%; exogenous = 33.4 +/- 9.1%; total = 29.9 +/- 12.0%). These comparisons indicate that differential absorption of endogenous and exogenous cholesterol can occur over a 1- or 2-meter segment of the upper small intestine, and that the rate of cholesterol absorption is critically dependent on the physicochemical state of the intralumenal contents. Our results indicate that currently available methods for measurement of cholesterol absorption (most of which are based on the use of radioisotopic sterols for differentiating exogenous from endogenous cholesterol) reliably quantitate the absorption of dietary cholesterol, and that the results of such tests are not significantly confounded by in vivo isotopic exchange.

Aged↗
PubMed1982

Epidemiology in anaesthesia. III: Mortality risk in patients with coexisting physical disease.

The Cardiff Anaesthetic Record System has been used to examine the hospital mortality rates and relative risks for patients having anaesthesia who have certain preoperative conditions coexisting with their disease requiring surgery. Each preoperative condition was associated with a higher mortality rate than occurred in patients with no preoperative condition (for example ischaemic heart disease 7%, diabetes 5.7%, no preoperative condition 0.5%). Mortality was greater for emergency than for elective operations. In contrast to an increasing mortality by age, the relative mortality risk decreased, suggesting that in older age groups coexisting disease may be less important than other risk factors in determining mortality.

Adolescent↗
PubMed1982

Effect of gemfibrozil on serum lipids in man.

The effect of gemfibrozil, a new lipid-lowering agent, was studied in 22 patients. Each patient served as his own control in a double blind study. The administration of gemfibrozil, for a period of 24 months, 1200 mg daily, reduced mean serum triglyceride levels by 45.6% (p less than 0.001) and mean serum cholesterol levels by 8.3% (p less than 0.001). Mean serum HDL cholesterol was increased by 32.3% (p less than .0001) and mean serum LDL cholesterol levels were decreased by 11.4% (p less than 0.01). Mean serum VLDL cholesterol was decreased by 45.9% (p less than 0.001). A 3-hour glucose-tolerance test was done in each patient during a placebo-control period and during the administration of gemfibrozil. Mean plasma glucose was moderately increased during the administration of gemfibrozil at all points on the glucose tolerance curve, and to levels of significance at one (p less than 0.05) and two hours (p less than 0.02). There was no effect of the drug on serum immunoreactive insulin. No subjective side effects were apparent.

Adult↗
PubMed1982

[Combined fracture-dislocation of both bones of the forearm at the elbow (author's transl)].

The authors have studied a particular type of traumatic lesion of the elbow which combines a fracture of the olecranon with a dislocation of both bones of the forearm, the radius and ulna remaining normally aligned to one another. The displacement was either forward (4 cases) or backward (6 cases). In some cases a partial fracture of the radial head or the lateral condyle of the humerus was also present and resulted in considerable instability. Internal fixation should always be tried but was not always possible. In one case a pedicle transplant of the medial epicondyle was made to restore a fractured coronoid process.

Adult↗
PubMed1982

Further validation of the plasma isotope ratio method for measurement of cholesterol absorption in man.

Recently we evaluated an isotope ratio method (IRM) for measurement of cholesterol absorption in 14 patients (15 experiments) hospitalized in the metabolic ward by comparing it to simultaneous measurements with a fecal radioactivity method (FRM) and found good to excellent agreement between two procedures (Samuel, P., J. R. Crouse, and E. H. Ahrens, Jr. 1978 J. Lipid Res. 19: 82-93). This comparison has now been extended to additional studies carried out in eight hospitalized patients (19 experiments). Of the 34 comparisons between the IRM and the FRM in our hands, 29 were technically acceptable (chromic oxide fecal recovery >/=80%): percent cholesterol absorption was 43.1 +/- 12% by the FRM and 46.0 +/- 11% by the IRM, exhibiting an accuracy within 3.5% at the 95% and 4.7% at the 99% confidence levels. In addition, various procedural modifications of the IRM were studied in out-patients. The measurement of isotope ratios in a single blood sample (analyzed in sextuplicate) on the third day (or later) following the tests gave identical results to those obtained from six to eight daily blood samplings. Blood samples drawn at any time during the day gave cholesterol absorption values similar to those obtained from samples drawn following an overnight fast. Absorption tests carried out before and 1 hr after breakfast, lunch, or dinner, or giving the oral isotope in three divided daily doses all yielded identical results with tests carried out in the am in the fasting state. Cholesterol absorption was markedly reduced when the oral radiolabeled cholesterol was administered in orange juice vs. liquid formula, milk or a solution of glucose and amino acids, consistent with the well-known fact that gallbladder contraction is a critical requirement of cholesterol absorption. A meal high in cholesterol consumed on the day of the test did not influence the results of the absorption measurements. Furthermore, addition of three eggs per day (~750mg cholesterol) for 3 weeks to a low-cholesterol poly-unsaturated fat diet caused no significant change in percent cholesterol absorption in any of eight patients. We conclude that the isotope ratio method accurately and precisely measures cholesterol absorption in man, and that it is suitable not only for in- but also for out-patient studies.-Samuel, P., D. J. McNamara, E. H. Ahrens, Jr., J. R. Crouse, and T. Parker. Further validation of the plasma isotope ratio method for measurement of cholesterol absorption in man.

Absorption↗