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Biomedical subjects

M E Conrad

Publications and source records attributed to M E Conrad.

At least 127 records · Page 7Linked to original sources
PubMed1975

Etiological spectrum of post-transfusion hepatitis.

Frequent occurrence of post-transfusion hepatitis continues despite screening for Australia antigen in blood before transfusion and elimination of commercial donor sources. The majority of these cases appears unrelated to hepatitis B virus. Preoperative, acute, and convalescent serra were screened for evidence of hepatitis B, hepatitis A, Epstein-Barr, and cytomegalovirus exposure in 34 cardiac surgery patients developing post-transfusion hepatitis postoperatively. Four patients showed evidence of hepatitis B infection and 3 patients developed significant antibody titer rises to cytomegalovirus. No patient showed evidence for acute hepatitis A infection postoperatively in response to blood transfusions. Epstein-Barr virus was also not responsible for any cases of post-transfusion hepatitis. Presently available laboratory methods failed to implicate hepatitis A, Epstein-Barr, or cytomegalo-virus in the majority of non-B post-transfusion hepatitis cases. This suggests that identification and characterization of additional hepatitis-producing agents will be required to define further the epidemiology of post-transfusion hepatitis and develop measures for its prevention.

Antibodies, Viral↗
PubMed1975

In vivo hepatic and intestinal toxicity of sodium cyanate in rats: cyanate-induced alterations in hepatic glycogen metabolism.

To determine the hepatic and intestinal toxicity of sodium cyanate, this compound was administered to rats by orogastric tube (PO) or intraperitoneal injection (IP). At low dosage (50 mg. per kilogram per day PO for 8 weeks), the animals showed no clinical effects other than mild lethargy. They had normal intestinal absorption studies, but demonstrated decreased liver G6PD activity and a slight increase in hepatic glycogen. At higher dose levels (200 mg. per kilogram per day PO for 10 days, 400 mg. per kilogram per day PO for 3 days, and 100 mg. per kilogram per day IP for 10 days), the animals became very lethargic and developed hind-limb paralysis; many animals died during the period of dosing. The severity and rate of onset of symptoms increased proportionally with the dose level. Liver sections from rats receiving these higher doses showed striking increases in glycogen deposition. Activities of hepatic enzymes involved in glycogen synthesis and degradation were measured in rats receiving 200 mg. per kilogram per day PO or 100 mg. per kilogram per day IP. Significant decreases were noted in the activities of glucose-6-phosphatase and G6PD in PO-dosed rats. The activities of phosphorylase, UDPG-pyrophosphorylase, glycogen synthetase, phosphoglucomutase, and debrancher did not differ from control rats. In IP-dosed rats, significant decreases were observed in the activities of glucose-6-phosphatase, G6PD, phosphorylase, and UDPG-pyrophosphorylase, but not in the other glycogen-related enzymes. Our data suggest that sodium cyanate affects several enzymes of hepatic glycogen metabolism but that the enzymes vary in their susceptibility (glucose-6-phosphatase and G6PD greater than phosphorylase and UDPG pyrophosphorylase.

Animals↗
PubMed1975

Role of sialic acid in erythrocyte survival.

The role of membrane sialic acid in erythrocyte survival is unclear, although there is evidence for a reduction in sialic acid and surface charge in older erythrocytes. We reduced the surface charge of human, rat, and rabbit erythrocytes by removing sialic acid with neuraminidase. Reduction in sialic acid correlated with decreases in electrophoretic mobility and loss of PAS staining of membrane glycoproteins on polyacrylamide gels. No changes in ATP levels or deformability were found. 51Cr erythrocyte survivals in rats and rabbits showed rapid clearance of desialylated erythrocytes with sequestration by the liver. These results suggest that reduction in erythrocyte sialic acid is a mechanism of erythrocyte destruction and may be important in erythrocyte senescence.

Animals↗
PubMed1975

Effect of blood in the gut on measurements of endogenous carbon monoxide production.

Changes induced in measurements of endogenous carbon monoxide (CO) production by blood in the lumen of the gut were studied in five normal volunteers. The study was undertaken because exogenous heme is absorbed by intestinal mucosal cells where the porphyrin ring is split with the release of CO that could contribute to blood CO levels and lead to a fallacious diagnosis of hemolytic disease. Volunteers who consumed 200 ml of their own blood doubled their endogenous production of CO (0.69 versus 0.34 mumoles/kg/hr). This suggested that at least 3% of the ingested heme was degraded and recovered as CO within 2 1/2 hr. Measurements of serum bilirubin also showed a significant increase after ingestion of blood. These data indicate that blood in the gastrointestinal tract can interfere with quantification of heme and bilirubin turnover from measurements of either endogenous CO production or bilirubin and suggest that this might occur with the ingestion of meat.

Blood Physiological Phenomena↗
PubMed1973

Tissue factor activity in lymphocyte cultures from normal individuals and patients with hemophilia A.

The procoagulant material of lymphocytes has been characterized as tissue factor. Lymphocytes stimulated with phytohemagglutinin or the purified protein derivative of the tubercle bacillus developed procoagulant activity with incubation in tissue culture. While this material corrected the prolonged clotting time of factor VIII (AHF) deficient plasma, we have shown, utilizing a sensitive radioimmunoassay, that no AHF antigen was present in the cell cultures. Further, we have demonstrated this material to be tissue factor by coagulation techniques and immunological cross-reactivity. The published data regarding factor VIII synthesis is reviewed in light of these observations and comments are made regarding the role of the lymphocyte procoagulant.

Animals↗
PubMed1973

Trypsin-like nature of the pancreatic factor that corrects vitamin B12 malabsorption associated with pancreatic dysfunction.

Hog pancreas was subfractionated and assessed for its ability to correct vitamin B(12) malabsorption in patients with pancreatic dysfunction and in rats with partial pancreatic extirpation. The constituent obtained from the pancreas that increased vitamin B(12) absorption in both humans and rats was soluble at 50,000 g, heat labile, acid stable, and approximately 20,000-25,0000 in molecular weight. The active subfractions contained tryptic and chymotryptic but no amylase or lipase activity. Thrice-crystallized trypsin corrected the vitamin B(12) malabsorption in both patients with pancreatic insufficiency and in rats with subtotal pancreatectomy. These data indicate that pancreatic proteolytic enzymes-in particular, trypsin-are necessary for optimal vitamin B(12) absorption.

Amylases↗