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Biomedical subjects

F R Smith

Publications and source records attributed to F R Smith.

86 records · Page 5Linked to original sources
PubMed1970

Radioimmunoassay of human plasma retinol-binding protein.

A radioimmunoassay for human plasma retinol-binding protein (RBP) has been developed utilizing a double antibody precipitation technique. RBP was purified 1500- to 2000-fold by procedures described previously. A specific anti-human RBP antiserum was prepared in rabbits by three once-weekly injections of purified RBP emulsified with Freund's adjuvant. RBP was iodinated with (131)I and the RBP-(131)I was purified by gel filtration on Sephadex G-100 after complex formation with human plasma prealbumin. The RBP-(131)I was completely (> 95%) immunoprecipitable in the presence of an excess of specific antiserum, it was not (< 5%) immunoprecipitable in the absence of specific antiserum, and it could be completely displaced from antibody by excess unlabeled RBP. The standard curve obtained in the immunoassay with normal plasma was identical to that with pure RBP. Duplicate samples differed from their mean by 5 +/-5% (+/-SD). There was a quantitative recovery of pure RBP added in varying amounts to normal plasma. The immunoassay accurately measured RBP in amounts of 10-100 ng per assay tube. There was no significant difference in the immunoreactivity of apo-RBP as compared to holo-RBP. The mean plasma values (+/-SEM) for a group of 76 normal subjects were 47.2 +/-1.6 mug/ml for males and 41.6 +/-1.6 mug/ml for females. Plasma RBP levels were markedly depressed (15 +/-2.3 mug/ml) in 14 patients with acute viral hepatitis. There was a highly significant correlation between the plasma levels of RBP and of vitamin A in both normal subjects and patients with hepatitis. In all subjects plasma RBP was generally saturated with retinol. The data suggest that under normal circumstances RBP circulates almost exclusively as the holoprotein.

Animals↗
PubMed1969

Vitamin A and carotenoids. The enzymic conversion of beta-carotene into retinal in hog intestinal mucosa.

The conversion of beta-carotene into retinal was studied in vitro with enzyme preparations from homogenates of hog intestinal mucosa. The hog mucosal enzyme was purified about 27-fold by precipitation with ammonium sulphate, chromatography on DEAE-Sephadex and gel filtration on Sephadex G-200. The reaction displayed a narrow optimum pH range (approx. 7.8-8.2). The enzyme was stimulated strongly by the addition of thiols, and was inhibited by thiol inhibitors and by the chelating agents alphaalpha'-bipyridyl and o-phenanthroline. The reaction required the addition of an appropriate detergent (or bile salt); maximal activity was obtained by addition of an appropriate combination of detergents and lipid (specifically Tween 40, sodium glycocholate and sphingomyelin). The reaction displayed Michaelis kinetics with K(m)1.3x10(-6)m and V(max.)1.1nmole of retinal formed/hr. (for 0.7mg. of enzyme protein). The properties of the hog enzyme are similar to those previously reported for a less purified rat enzyme preparation.

Animals↗
PubMed1969

Lipids of Acanthamoeba castellanii. Composition and effects of phagocytosis on incorporation of radioactive precursors.

The lipids of Acanthamoeba castellanii (Neff) consist of 52% neutral lipids and 48% polar lipids. Triglycerides account for 75% and free sterols for 17% of the neutral lipids. The major phospholipids are phosphatidylcholine (45%), phosphatidylethanolamine (33%), phosphatidylserine (10%), a phosphoinositide (6%), and diphosphatidylglycerol (4%). The phosphoinositide is unique in that it contains fatty acids, aldehyde, inositol, and phosphate in the ratio of 1.4:0.5:1.1, but it contains no glycerol. Sphingomyelin, cerebrosides, psychosine, and glycoglycerides were not detected, but small amounts of unidentified long chain bases and sugars are present. The rates of uptake of palmitate-1-(14)C and of its incorporation into glycerides and phospholipids were not affected by the phagocytosis of polystyrene latex beads. Although phagocytosis usually decreased the uptake by amebas of phosphate-(32)P, serine-U-(14)C, and inositol-2-(3)H, their subsequent incroporation into phospholipids was not demonstrably stimulated or inhibited by phagocytosis. Phagocytosis did seem to increase the incorporation into ameba phospholipids of phosphatidylcholine-1 ,2-(14)C but not that of phosphatidylethanolamine-1 ,2-(14)C. These experiments, in which the incorporation of radioactive precursors into total cell lipids was measured, do not, of course, eliminate the possibility that localized effects may occur.

Aldehydes↗
PubMed1968

7-Dehydrostigmasterol and ergosterol: the major sterols of an amoeba.

The sterol fraction of Acanthamoeba (Neff) contains 60% 7-dehydrostigmasterol and 40% ergosterol. The sterols were characterized by infrared and ultraviolet spectroscopy, gas chromatography, specific reactions, and mass spectral analysis. Sterols constitute 5% of the lipids and 15% of the neutral lipids in this species.

Amoeba↗
PubMedDate not supplied

Effects of lipoproteins on plasma viscosity.

Patients with hypertriglyceridemia and mixed hyperlipidemia have been found to have mean plasma viscosities significantly higher than controls (P less than 0.005). In a group of 70 hyperlipidemic patients and controls, plasma viscosity was correlated with plasma triglyceride concentration (r = 0.56, P less than 0.01) and to a lesser extent with the concentration of plasma cholesterol (r = 0.29, P less than 0.05). When isolated lipoprotein fractions were added to lipoprotein-free plasma in increasing concentration over a physiological range, a highly significant linear relationship between plasma viscosity and chylomicron concentrations (r = 0.98, P less than 0.001) was apparent. Furthermore, when chylomicrons were removed by ultracentrifugation, viscosity returned to baseline levels. Added VLDL produced a lesser effect (r = 0.70, P less than 0.001) and added LDL, over the range of cholesterol concentration studied, had no influence on viscosity. These studies indicate that chylomicrons in particular can increase plasma viscosity. Viscosity increases of the magnitude demonstrated may in turn alter blood flow and thus contribute to symptoms such as intermittent claudication. Chylomicron-induced increases in plasma viscosity and subsequent decreases in local pancreatic blood flow may be one of the factors involved in the known relationship between severe chylomicronemia and acute pancreatitis.

Blood Viscosity↗
PubMedDate not supplied

Evaluating the changing role of respiratory therapy services at two hospitals.

An analysis of respiratory therapy services at two general hospitals showed a notable change from 1971 to 1979. There was a large decrease in intermittent positive-pressure breathing (IPPB) treatments at both hospitals. These were partially replaced with general chest physiotherapy maneuvers at one hospital and with incentive spirometry at another. Both hospitals demonstrated a substantial increase in time spent in management of mechanical ventilators. Staffs had increased along with time spent per patient. The reduction in IPPB was not associated with lower costs of respiratory therapy service at either hospital but, rather, a shift in the types of service performed. These changes must be considered in determining cost-effectiveness of respiratory therapy services.

Cost-Benefit Analysis↗