Effect of somatostatin on small intestine enzyme activities in rat and chick

The influence of somatostatin injection on intestinal disaccharidase and alkaline phosphatase activity in rat and chick was investigated. Disaccharidase and alkaline phosphatase activities of rat and chick homogenates were not modified. In rat the activities of mucosal brush-border maltase and sucrase were significantly increased. In chick brush-border a significant increase of duodenal mucosal activity and duodenal and jejunal sucrase activity is observed.

Control of gastric glucagon secretion in the acutely pancreatectomized rat

Glucagon immunoreactivity (IRG) was measured in portal plasma from control and pancreatectomized rats and in arterial plasma from eviscerated rats with a functional liver. Portal IRG was 0.41 ± 0.02 ng/ml in control rats and 0.22 ± 0.01 in pancreatectomized rats. After evisceration, values of 0.08 ± 0.01 ng/ml were found (unextracted plasma, antiserum 30 K). Acid-ethanol plasma extracts demonstrated lower values, but a similar stepwise decrease was observed after pancreatectomy, then gastrectomy. Rat gastric extracts contained a low concentration of IRG (approximately 1/1200 the C-terminal IRG concentration of the corresponding pancreas). No IRG-positive cells were detected by immunofluorescence in the gastric mucosa.

In the pancreatectomized rats, portal IRG remained stable for 75 min in the absence of further manipulation. From IRG concentrations and hepatic blood flow estimation in both control and pancreatectomized rats, the contribution of the stomach to portal IRG in the basal state could be estimated as 20% of the total. Gastric IRG release was increased by acute hypoglycemia (peak value 0.75 ± 0.18 ng/ml; N = 10; P < 0.01) and by 2-deoxyglucose infusion (0.45 ± 0.15 ng/ml; N = 4; P < 0.05). Administration of glucose + insulin induced a decrease in portal IRG (0.13 ± 0.01 ng/ml; N = 4; P < 0.001). Vagal stimulation and arginine infusion induced a rise in portal IRG: 0.84 ± 0.27 ng/ml (N = 10; P < 0.05) and 0.31 ± 0.03 ng/ml (N = 9; P < 0.01), respectively, while portal insulin remained low or undetectable (0-18 μu/ml). A rise in blood glucose accompanied the increase of plasma IRG. A concomitant insulin-induced hypoglycemia (36 ± 5 mg/dl) strongly potentiated the effects of both arginine infusion (1.46 ± 0.47 ng/ml; N = 6; P / 0.005) and vagal stimulation (1.39 ± 0.47 ng/ml; N = 4; P < 0.005).Higher IRG values were observed after pancreatectomy in alloxan-diabetic rats: 0.36 ± 0.02 ng/ml (N = 3; P < 0.001).

We conclude therefore that: (a) the rat stomach contributes to the release of IRG in blood but to a limited extent, (b) the factors controlling this release appear very similar to those controlling pancreatic A cells; and (c) gastric IRG may be hyperglycemic in the rat.

Hepatitis B prevalence within a dental student population

In this descriptive epidemiologic study, prevalence rates of hepatitis B surface antigen (HBsAg) and its antibody (anti-HBs) among fourth-year dental students and second-year dental hygiene students were found to be comparable to those of a control population and a local age-adjusted blood donor group. This observation contrasts with the rates reported for practicing dentists, especially oral surgeons, and indicates that the increased risk experienced by dentists after dental school may be attributable to potentially greater exposure to the hepatitis B virus resulting from an expanded patient load. No significant correlation was found between a positive serologic response and several potential risk factors: previous liver disease, prior contact with hepatitis patients, parenteral injections, facial hair, and punctures sustained during dental procedures. In contrast, prevalence of HBsAg and anti-HBs was increased significantly among black students.

Multiplication of Coxsackie B1 virus in synchronized HeLa cells

A higher yield of Coxsackie B(1) virus was obtained when HeLa cells were infected late during S phase as compared to the amount produced by random cultures.

Cell-mediated immunity in guinea pigs to subunits derived from hepatitis B surface antigen

Guinea pigs immunized wit- hepatitis B surface antigen (HBSAg), types adw and ayw, and with two polypeptides (400,000 and 24,000 molecular weight) developed cell-mediated immunity (CMI), as determined by radioimmunoassay. Peritoneal exudate (PE) cells from guinea pigs immunized with the 40,000-molecular-weight polypeptide migrated poorly (30 to 88% inhibition) after challenge with the immunizing subunit or with purified HBSAg, type gdw or ayw. Response of the same PE cells to the 24,000-molecular-weight subunit was significantly reduced. Similar but less striking evidence for CMI was observed was PE cells derived from guinea pigs inoculated with purified type-specific HBSAg or with the 24,000-molecular-weight polypeptide. Humoral responses were predictable and showed a reasonable degree of correlation with the CMI response. PE cells from control animals inoculated with normal human serum or polyacrylamide gel were not inhibited after challenge with purified preparations of HBSAg or with the 400,000-molecular-weight polypeptide, but did show CMI with their respective immunogens. In addition, PE cells from guinea pigs inoculated with normal human serum were inhibited from migrating after challenge with the 24,000-molecular-weight subunit, suggesting that the latter may contain an antigenic determinant related to a human serum protein.

Production of antibody to individual polypeptides derived from purified hepatitis B surface antigen

Purified preparations of hepatitis B surface antigen (HBsAg) were solubilized with sodium dodecyl sulfate and urea under reducing conditions and subsequently fractionated by preparative sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis (PAGE). Pools of the individual fractions eluted from the preparative PAGE were concentrated and purified further by analytical PAGE. Five purified polypeptides were isolated from HBsAg, types adw and ayw, with molecular weights of 19,000, 24,000, 27,000, 35,000, and 40,000. Each preparations was emulsified in Freund complete adjuvant and injected into guinea pigs. Antibody to each HBsAg type was measured by radioimmunoassay. The 19,000 molecular weight polypeptide derived from ayw particles and the 27,000 molecular weight subunit obtained from both types failed to elicit an antibody response. The other three polypeptides derived from the ayw particles elicited group-specific antibody responses. Similar group-specific reactivities were observed in the testing of anti-adw 35,000 and anti-adw 40,000 molecular weight polypeptide sera. However, guinea pigs immunized with the 19,000 and the 24,000 molecular weight polypeptides of the adw type produced antibody that reacted preferentially with adw particles. This indicates that either these subunits carry predominately d determinants or that, because of the low levels of material used for inoculation, no immune response or an undetectable one was elicited to the a or w components.