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Biomedical subjects

R Hill

Publications and source records attributed to R Hill.

At least 235 records · Page 13Linked to original sources
PubMed1981

A comparison of the physicochemical properties of carcinoembryonic antigen in extracts of tumour tissue, ascitic and cyst fluid from ovarian cancer.

In view of the reported disagreement in the physicochemical properties of ovarian carcinoembryonic antigen (CEA), this study was undertaken to compare the properties of CEA obtained from extracts of ovarian tumour tissue, ascitic fluid and cyst fluid. On the basis of molecular weight estimation and binding properties with Concanavalin A and wheat germ lectin, ovarian CEA from these three sources appeared similar, and also possessed similar properties to those of colonic CEA. On isoelectric focusing, however, it was found that the isoelectric point of CEA from tumour tissue and cyst fluid differed from that from ascitic fluid. It is most likely that this is due to a loss of sialic acid from the CEA released into ascitic fluid.

Ascites↗
PubMed1980

Neurotrophic influence on lobster skeletal muscle.

The correlation between histochemical properties of muscle fibers and the pattern of innervation by the two motor neurons was studied in the asymmetric claw closer muscles of the lobster. The closer muscle of the cutter claw is composed of 65 percent fast muscle fibers and 35 percent slow muscle fibers, whereas that in the crusher claw has all slow muscle fibers. In both claws, myofibrillar adenosinetriphosphatase activity was independent of the pattern of innervation. Oxidative capacity, as measured by reduced nicotinamide adenine dinucleotide activity, was correlated with motor axon presence: Muscle fibers innervated solely by the "fast" motor axon had low oxidative capacity, muscle fibers receiving only the slow motor axon had very high oxidative capacity, and fibers innervated by both axons had intermediate properties. The data suggest that the motor neurons may exert trophic influences that control certain muscle fiber properties but not others.

Adenosine Triphosphatases↗
PubMed1980

The induction and characterization of mouse lymphoma L5178Y cell lines resistant to 1-beta-d-arabinofuranosylcytosine.

The induction of variants of L5178Y mouse-lymphoma cells resistant to 1-beta-D-arabinofuranosylcytosine (ara-C) has been investigated. The spontaneous mutation frequency was low, around 3 X 10(-8). Resistant variants were induced in a dose-dependent fashion following treatment with ethyl methanesulphonate (EMS), ethidium bromide and 2-acetylaminofluorene, but not with gamma-irradiation. With EMS as mutagen the frequency of ara-C-resistant variants was much lower than that obtained using other selective agents, whereas it was higher with the mutagens acetylaminofluorene and ethidium bromide. Out of 42 resistant clones examined, 38 showed normal sensitivity to thymidine and were destignated as Class 1, the remaining four (Class 2) were usually resistant to thymidine. Cells in Class 1 did not accumulate detectable amounts of ara-C and had negligible deoxycytidine kinase activity. They were about 3000-fold more resistant to the toxic effects of ara-C than were wild-type cells. Cells in Class 2 had a reduced ability to accumulate are-C and had 50% of the deoxycytidine kinase activity of wild-type cells. They were only 20 times more resistant to ara-c than were wild-type cells. The enzymatic defect in these cells is obscure but the phenotypic properties probably result from subtle alterations in the pool of deoxycytidine nucleotides.

2-Acetylaminofluorene↗
PubMed1980

A preliminary investigation of the role of dynamic computed tomography in renovascular hypertension.

This preliminary report describes the application of dynamic computed tomography (CT) to the study of the kidney. The study is a simple, rapid, noninterventional test that gives time--density perfusion curves for the renal cortices as compared with aortic perfusion. In normal subjects, renal cortical time--density curves almost parallel the aortic time--density curve. In theory, decreases in perfusion in the kidney should show a renal cortical perfusion curve that is flattened and no longer parallel to the aortic curve. An experimental model for renal infarction was developed in the dog. Time--density curves taken from the infarcted area do show a depressed renal perfusion curve, with a lower peak than the curve for the contralateral kidney. Dynamic CT may be useful in screening human subjects for possible renovascular hypertension.

Animals↗
PubMed1980

Plasma enzyme activities indicative of liver cell damage in laying fowl given a diet containing 20 per cent of rapeseed meal.

The effects of a diet containing a high proportion of rapeseed meal on the activity of certain plasma enzymes were studied in laying birds. The enzymes studied were alkaline phosphatase (AP), aspartate transaminase (AST), L-gamma-glutamyl-transferase (gamma-GT), isocitrate dehydrogenase (ICDH), leucine arylamidase (LAP), malate dehydrogenase (MDH) and sorbitol dehydrogenase (SDH). No notable differences were observed between the plasma AP, LAP or SDH activities of the birds given the rapeseed meal and the birds receiving a soyabean meal control diet throughout the experiment. However, the plasma AST and gamma-GT activities of the treated birds showed slight elevations while their plasma ICDH and MDH activities showed more marked elevations, which are indicative of liver damage, in response to the diet. Macroscopic observations of the livers of the birds at the end of the experiment were in fairly good accord with the elevation in plasma ICDH and MDH activities noted for the individual birds.

Alkaline Phosphatase↗
PubMed1980

The effects of added dietary iron in various forms on mice inoculated with Salmonella typhimurium.

The susceptibility of mice to intraperitoneal infection with 10(4.8) living bacteria of three strains of Salmonella typhimurium was measured in groups fed either a basal, nutritionally adequate diet or the same diet to which had been added ferric iron in one of six forms: ferric sulphate or chloride (FeS), ferric ethylenediaminetetra-acetate (FeE), ferric nitrilotri-acetate (FeN), ferric fructose (FeF), ferric diethylenetriaminepenta-acetate (FeT) and ferric ethylenediamine di (O-hydroxyphenylacetate) (FeD). FeN and FeF significantly increased the survival rate of male but not female mice. This protective effect of FeN was not influenced by its concentration in the diet over the range tested, 25 to 800 mg of Fe per kg of diet. FeN had to be given a week before infection to produce the effect and it was associated with a reduced rate of multiplication of salmonellae. FeE significantly decreased the survival rate of both male and female mice, and greatly reduced the survival time of mice that died. The deleterious effect of FeE increased with its concentration in the diet and with the time for which it had been fed, and it was associated with very rapid bacterial multiplication. FeT gave results similar to those of FeE, while FeS and FeD had hardly any effect.

Animals↗
PubMed1980

Haemorrhagic liver syndrome in laying fowl fed diets containing rapeseed meal.

Liver haemorrhage was studied in laying fowl given diets containing rapeseed meals prepared from seed of varieties of Brassica napus grown in the United Kingdom and from seed of the varieties Tower and Erglu. There was lower mortality from liver haemorrhage in birds given Tower than in those given B napus (UK) meal but haemorrhagic lesions in the liver occurred in all groups of birds given rapeseed meal diets, whichever meal was included. Histological and electron microscopical examination revealed several abnormalities in the structure of the hepatocytes. Early degenerative changes were, enlargement of the intercellular spaces, swelling of the mitochondria, distortion of the rough endoplasmic reticulum profiles, disruption of the hepatic sinusoids, and in the most severely affected areas there were necrotic hepatocytes. These abnormalities were observed in sections from the livers of two hybrid strains of birds given the B napus (UK) or Tower rapeseed meal for four weeks or longer.

Animal Feed↗
PubMed1979

Methylmalonic acidemia: 6 years' clinical experience with two variants unresponsive to vitamin B12 therapy.

Two infants with lethargy, vomiting, convulsions, coma and marked metabolic acidosis were found to have very high concentrations of methylmalonic acid in their serum and urine. In vitro studies of fibroblasts demonstrated that the infants had different variants of methylmalonic acidemia.Vitamin B(12) was given in two different forms at 1 month of age and at 12 months of age. Each trial continued for 4 months but neither infant showed a clinical or biochemical response.In both infants hyperglycinemia, neutropenia and thrombocytopenia developed during acute metabolic crises only. Hypoglycemia was found in patient 2. Hyperammonemia was severe in patient 2 during acute crises but never appeared in patient 1. When clinically well, both infants continued to excrete abnormal amounts of methylmalonic acid in the urine and both had persistent compensated metabolic acidosis.Marked hyperuricemia developed in patient 1 at 18 months of age and led to progressive renal failure. Allopurinol therapy was necessary to keep the uric acid concentration within the normal range. Renal function returned to normal, as indicated by a marked increase in the renal clearance of creatinine and uric acid.Patient 1 is physically and mentally retarded, and has moderate hypotonia, hepatomegaly and persistent vomiting. Patient 2 has developed normally.The urine concentrations of methylmalonic acid in the four parents were normal.

Amino Acid Metabolism, Inborn Errors↗
PubMed1979

Naturally occurring lymphocyte-mediated immunity to endogenous type-C virus in the mouse. Blocking of the lymphocyte reactivity with antisera to the virus.

The natural immune response in mice to their endogenous type-C viruses involves a complex interaction between cellular and humoral immune mechanisms. The virus-specific immune reactivities are a function of age and appear only subsequent to endogenous virus expression. Cellular immune activity was found to reside in a population of lymphocytes that were characterized as natural killer cells based on their absence of theta surface antigens or immunoglobulin or complement receptors. Cellular and humoral virus-specific immune responses co-occur in the same animal and pretreatment of virus-positive target cells with sera from virus-positive aging mice is capable of partially blocking the cytotoxic activity of reactive lymphocytes. The blocking activity of sera from individual mice increases as a function of age and endogenous virus expression and is highly correlated with the virus-specific complement-dependent cytotoxic activity of these sera. Mouse sera, whether naturally immune or immune as a result of hyperimmunization with type-C virus, exhibit blocking activity that can be removed by absorption with purified type-C virus or purified viral glycoprotein (gp 70) but not by absorption with noninfected syngeneic cells. High-titered and highly specific antisera directed against certain individual R-MuLV structural proteins reveal blocking activity. Monospecific antisera to gp 70 and p 12 exhibited high-titered blocking reactivities which are absorbable by the respective purified proteins. Blocking activity of antisera directed against other viral structural proteins could not be excluded with certainty. These findings raise the possibility that immunity in the mouse to endogenous type-C virus or virus-infected cells involves competition between serum-blocking activity and natural-killer cell activity and further provides a unique model system for studying the mechanism of action of blocking antisera known to have monospecific reactivity against defined and purifiable transplantation antigens.

Aging↗