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T M Saba

Publications and source records attributed to T M Saba.

187 records · Page 11Linked to original sources
PubMedDate not supplied

Effect of endotoxin on fibronectin and Kupffer cell activity.

The phagocytic activity of the reticuloendothelial system (RES) in the liver is important in host resistance to shock. Fibronectin is a large molecular weight glycoprotein which influences particulate uptake by phagocytic cells. This study addressed the effect of repeated low-dose endotoxin challenge on immunoreactive fibronectin and reticuloendothelial phagocytic function in rats. Intravenous Escherichia coli endotoxin increased circulating immunoreactive fibronectin by 100% within 24 hr; normalization was within 96 hr. Elevated fibronectin levels at 48 hr were associated with increased plasma opsonic activity as tested by liver slice phagocytic assay and RES stimulation, and in vitro uptake of gelatinized target particles by Kupffer cells in liver slices from endotoxin treated rats was significantly increased. Endotoxin tolerance was produced by repeated low dose challenge with endotoxin for 7 days and was associated with RES stimulation, even though the circulating fibronectin concentrations had returned to normal. By immunofluorescence, insoluble fibronectin was widely distributed in the liver in a pattern analogous to the sinusoidal vascular network. We suggest that increased RES phagocytic activity after low dose endotoxin challenge is due to early elevation of plasma fibronectin and cellular stimulation of phagocytic function followed by a sustained stimulation of Kupffer cells in the presence of normal fibronectin levels. Both cellular and humoral factors may contribute to increased Kupffer cell phagocytic activity during endotoxin tolerance.

Animals↗
PubMedDate not supplied

Decreased plasma fibronectin during starvation in man.

This study evaluated the effect of 5 days of starvation followed by 5 days of refeeding on immunoreactive plasma and serum fibronectin and associated opsonic activity as studied by peritoneal macrophage monolayer bioassay in 12 healthy women volunteers. The temporal alteration of fibronectin was compared with the serum albumin, total iron-binding capacity, and retinol-binding protein levels. Fibronectin concentration and opsonic activity were also determined in two cachectic patients who were 61 and 78% of their ideal body weight. Prior to starvation, plasma fibronectin was 292 +/- 20 micrograms/ml and serum fibronectin was 182 +/- 16 in all subjects. After 5 days of starvation, immunoreactive fibronectin decreased (p less than 0.05) by 20-25%. This decrease was not great enough to impair opsonic activity as tested by the in vitro macrophage assay. Starvation caused no decrease in serum albumin or total iron-binding capacity, although retinol-binding protein decreased by 35%. During refeeding, subjects were randomized to a diet with (n = 6) and without (n = 6) carbohydrate. After 5 days of refeeding, fibronectin levels were normalized on the carbohydrate-containing diet, but were still low (82% of normal) on the carbohydrate-free diet. Retinol-binding protein did not fully normalize after 5 days of refeeding. In the two cachectic patients, fibronectin levels prior to total parenteral nutrition were 25 and 75% of normal. Thus, starvation can lower fibronectin levels and this protein is rapidly restored with adequate nutrition.

Adult↗