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Biomedical subjects

R A Chase

Publications and source records attributed to R A Chase.

At least 55 records · Page 3Linked to original sources
PubMed1977

Serum octopamine, coma, and charcoal haemoperfusion in fulminant hepatic failure.

Serum octopamine levels were significantly higher in twenty patients with fulminant hepatic failure (FHF) during the first 48 h of grade IV coma than in health control subjects (3.38 +/- 0.20 ng/ml and 1.75 +/- 0.19 ng/ml respectively, P less than 0.001). Serial measurements in five patients who died without regaining consciousness showed serum octopamine to remain raised, and concentrations in the cerebrospinal fluid at death reflected serum levels. In five patients who regained consciousness, improvement in encephalopathy was associated with a significant reduction in serum octopamine. Renal failure in patients with FHF was found to contribute to raised serum octopamine but could not alone account for the observed levels. Patients given neomycin therapy did not have significantly lower serum octopamine levels than an untreated group. There was, however, a significant correlation between elevated serum octopamine and the occurrence of gestrointestinal bleeding during the previous 24 h. Charcoal haemoperfusion did not appreciably reduce serum octopamine levels.

Charcoal↗
PubMed1976

Plasma and brain amino acids in fulminant hepatic failure and their relationship to hepatic encephalopathy.

Amino acid concentrations were determined in plasma, whole blood, cerebrospinal fluid and brain tissue of 45 patients with grade 3 or 4 coma due to fulminant hepatic failure. The concentration of 15 of the 19 amino acids determined were significantly increased in blood and the increases were greatest for the amino acids concerned with neurotransmitter metabolism. There was no correlation, however, between the plasma concentration of these amino acids and changes in the grade of hepatic coma. The plasma concentrations of the branched chain amino acids were normal except in those patients who subsequently recovered in whom levels were slightly decreased. Phenylalanine- tyrosine and methionine were among the 15 out of 18 amino acids which were significantly increased in cerebrospinal fluid and among the 15 out of 21 amino acids which were significantly increased in the brain. The increase in tryptophan was associated with a significant elevation in brain 5-hydroxyindoleacetic acid concentration suggesting an increase in 5-hydroxytryptamine turnover in hepatic coma. Brain to plasma ratios of most amino acids in hepatic coma patients were similar to control subjects suggesting that plasma concentration is the main factor controlling the cerebral concentration. However, for the branched chain amino acids, cerebrospinal fluid and brain concentrations were increased when plasma concentrations were normal suggesting an increase in brain uptake.

Amino Acids↗
PubMed1976

[Accurate reconstruction of traumatic bony contour defects of periobital area with prefabricated silastic].

The silicone inlay method of prefabricating subcutaneous and bony implants for congenital and acquired defects of the maxillofacial area was used in 25 cases. Heat vulcanized Silastic 372 or 373 was used, and seems to be satisfactory. The method is presented as a useful addition to the surgical restoration of subcutaneous and bony defects, particularly complex contours of the periorbital area when autogenous tissue is unavailable. Complications seem to be less common when the implant is immobile and secured to bone. The method is evolving, and modifications can and should be made in the technique.

Adult↗
PubMed1975

Exploitation of hormone-induced conformational changes to label selectively a component of rat liver plasma membranes.

The kinetics for inactivation of rat liver plasma membrane adenylate cyclase by iodoacetic acid and iodoacetamide has been measured in the presence and absence of glucagon. Glucagon stimulated the rate of iodoacetic acid inhibition by a factor 9f 2.3-fold and iodoacetamide inhibition by 10-fold. These results suggest that interaction of glucagon with its receptor in the membrane resulted in conformational changes which increased either the exposure or nucleophilicity of one or more sulfhydryl groups crucial for adenylate cyclase activity. Membranes were treated with radioactively labeled iodoacetamide or iodoacetic acid in the presence or absence of glucagon and run on 5 and 7.5% sodium dodecylsulfate polyacrylamide gels. These labeling experiments revealed that two membrane components were more extensively labeled in the presence of glucagon. The first component had an apparent molecular weight of 240,000 on sodium dodecyl sulfate gels and stained positive with Coomassie blue and periodate Schiff reagent. This polypeptide accounted for approximately 1.3% of the total membrane protein. The second component had an apparent molecular weight less than 10,000 and could not be correlated directly with a well defined protein band on sodium dodecyl sulfate polyacrylamide gels. The enhancement in labeling of the 240,000 molecular weight component seen in the presence of glucagon agreed very well with that predicted from the kinetics for inhibition of adenylate cyclase activity in the presence and absence of glucagon. This correlation suggests that the component selectively labeled by this technique may be an integral component of the adenylate cyclase system and that hormone-induced conformational changes may be used to selectively label components of the adenylate cyclase system in mammalian membranes.

Adenylyl Cyclases↗
PubMed1975

Disturbances in glucose metabolism in patients with liver damage due to paracetamol overdose.

1. Intravenous glucose tolerance test were performed in fourteen patients with mild or moderate liver damage due to paracetamol overdose. 2. In patients managed conservatively there was glucose intolerance associated with a diminished early insulin response to glucose, suggesting inadequate nutrition in the period between the overdose and the glucose tolerance test. 3. Patients given intravenous glucose supplements to maintain nutrition were also glucose intolerant and, in these, insulin responses to glucose were normal. The decreased fractional disappearance rate was partly due to an increase in glucose distribution space and partly due to a decrease in absolute glucose disappearance rate. 4. Impaired gluconeogenesis was suggested by mild fasting hypoglycaemia in four patients and raised fasting blood lactate concentrations. Serum growth hormone concentrations showed a paradoxical increase after glucose. 5. All these variables had returned to normal in four patients re-tested after recovery.

Acetaminophen↗