Uptake of polypeptide fragments of proteins by rat intestine in vitro and in vivo.

Minute amounts of intact proteins were previously shown to be taken up from the intestine into the systemic circulation of mature animals; fragments were not detected. In this study, we sought evidence for uptake of fragments in both in vitro and in vivo experiments. Polypeptide fragments produced by pepsin digestion of bovine serum albumin (ranging in molecular weight from approximately 6000 to 25,000) were labeled with 125I. Everted jejunal gut sacs prepared from rat intestine were incubated with labeled fragments. After incubation, fluid exposed to the serosal surface was applied to a Sephadex G-50 gel permeation column. Radioactivity was detected in fractions corresponding to the elution position of the fragments. Transfer of fragments from the mucosal to the serosal surface was temperature-dependent. In in vivo studies, labeled fragments were infused into the jejunum of rats. Blood samples obtained from a mesenteric vein or the portal vein contained labeled fragments. After infusion of unlabeled fragments, nanogram amounts of immunoreactive fragments were detected by radioimmunoassay of mesenteric and portal venous blood. Thus, polypeptide fragments of a potential food protein were capable of being transferred across the mucosa in vitro and in vivo. Failure to detect fragments in the systemic circulation most likely results from their rapid clearance.

Can insertion length for a double-lumen endobronchial tube be predicted?

It has been suggested that the appropriate length of insertion for double-lumen tubes can be estimated by external measurement. This study examined the accuracy of external measurement in estimating the actual length of insertion required in 130 patients. It also examined the relationship between the length inserted and the patient's height in 126 patients and their weight in 125 patients. Although there was a fair correlation between the measured external length and the final inserted length (r = 0.61), the 95% confidence intervals of slope and intercept allowed a large variation and the prediction was too wide to be clinically useful. Height was reasonably well correlated with the final length (r = 0.51) but an equally wide 95% confidence interval rendered it of little clinical value. There was no correlation between weight and final tube length. It is concluded that external measurement alone is not adequate to predict a clinically acceptable position of the double-lumen tube.

Immune complex-induced enteropathy in the rat. I. Clinical and histological features.

Adult male Sprague-Dawley rats injected with preformed rat anti-bovine serum albumin antibody-bovine serum albumin complexes prepared in fivefold antigen excess, developed intestinal lesions consisting of annular bands of serosal hyperemia alternating with nonhyperemic bands, causing a striped appearance. Histologically, vascular congestion and mucosal edema were observed; more severe lesions were accompanied by hemorrhage, epithelial necrosis and sloughing, and modest polymorphonuclear leukocyte infiltration. The lesions developed rapidly and were accompanied by hemoconcentration. A correlation between the dose of immune complexes injected and the intensity and extent of intestinal lesions was noted. The pathogenetic mechanism of the lesions was not determined. The similarity of the lesions to those observed in systemic anaphylaxis in the rat and experimental and clinical shock was cited. The implications of immune complex-induced enteropathy for studies of immune complex clearance by the mononuclear phagocyte system were considered.