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Biomedical subjects

R Huxtable

Publications and source records attributed to R Huxtable.

At least 19 recordsLinked to original sources
PubMed2004

Research ethics committees and paternalism.

In this paper the authors argue that research ethics committees (RECs) should not be paternalistic by rejecting research that poses risk to people competent to decide for themselves. However it is important they help to ensure valid consent is sought from potential recruits and protect vulnerable people who cannot look after their own best interests. The authors first describe the tragic deaths of Jesse Gelsinger and Ellen Roche. They then discuss the following claims to support their case: (1) competent individuals are epistemologically and ethically in the best position to say which risks are reasonable for them, so RECs should be no more restrictive than the "normal" constraints on people taking risks with themselves; (2) RECs do not judge individual competence (that is for researchers and psychiatrists); (3) individual liberty is mostly limited by what serves the public interest, and RECs do not determine public interest; (4) RECs may have a paternalistic role in preventing exploitation of competent people vulnerable to the use of incentives, and in protecting the interests of incompetent people; however, (5) the moral and political authority of RECs has not been established in this respect.

Altruism↗
PubMed2000

The Court of Appeal and conjoined twins: condemning the unworthy life?

The recent decision of the Court of Appeal authorising separation of the conjoined twins 'J' and 'M' appears susceptible to attack on the basis of various inconsistencies. Most fundamentally, the leading judgment of Ward LJ in Re A (Children) (2000) appears to involve a relative devaluation of M's life in consequentialist terms. One life is better than no life appears to be the message, an evaluation apparently reached by reference to 'Quality' of life considerations. But in his speech Ward LJ explicitly rejects such an approach.

Catholicism↗
PubMed1980

Taurine decreases lesion severity in the hearts of cardiomyopathic hamsters.

Cardiomyopathic Syrian hamsters develop necrotic lesions consequent upon calcium overload from 60 days of age onward. Taurine, given as a 0.1 M solution in place of drinking water for one month prior to sacrifice of animals of initial age 35 days, decreased the severity of subsequently developing cardiac lesions by 40%. Calcium concentration in the heart was decreased by 57%. Magnesium and iron concentrations were unaltered. Taurine given in a similar manner for 4 months had a protective effect, decreasing lesion severity by 21% and calcium concentration by 35%. Magnesium concentrations were increased by 12%. Compared to random-bred animals, cardiomyopathic hamsters at one and two months of age have the same concentrations of calcium, magnesium and iron in the quadrants of the heart, except in the left ventricle, which has significantly higher concentration of calcium. Calcium concentrations are 70%, 1320% and 2100% higher respectively in one month, two month and five month old animals. Five month old animals differ slightly but significantly in iron (17% decrease) and magnesium concentrations (17% increase). Cardiomyopathic hamsters have insignificant differences in beta-adrenergic receptor density compared to random-bred animals and have a significantly higher rate of taurine influx.

Adult↗
PubMed1979

The Syrian golden hamster: a model for the cardiomyopathy of Friedreich's ataxia.

In light of the available information on the cardiomyopathy of Friedreich's ataxia, the cardiomyopathic Syrian hamster may be an appropriate laboratory model. Cardiomyopathy in these animals is a result of calcium accumulation. We analyzed the atria and right and left ventricles from cardiomyopathic (CM) and random bred (RB) animals for calcium, magnesium, and iron concentrations at 30-40 and 60-70 days of age (age of maximum lesioning). There are no significant differences in the concentration of iron or magnesium among age-matched groups. The concentration of calcium in the left ventricles of the CM animals at 60 days old is 14 fold higher than that of RB animals. Although there is a significant difference in the concentration of calcium in the left ventricles of younger animals, it is not as pronounced as the difference in older animals. Analysis of the taurine concentration in 30-40 day old animals revealed that the CM animals show slightly higher taurine concentrations than RB in the whole heart. In 60 day old CM hamsters in the beta-adrenergic receptor density of the ventricles is unchanged. This indicates that calcium overload is not due to adrenergic supersensitivity.

Animals↗
PubMed1979

Regional distribution of amino acids in Friedreich's ataxia brains.

The distribution of amino acids in two Friedreich's ataxia brains is compared to 4 control brains. Glutamate and GABA were decreased in the cerebellar hemispheres and/or in the vermis. Taurine concentrations were uniformly elevated throughout the areas studied. Taurine/glutamate and taurine/GABA ratios were consistently elevated in Friedreich's ataxia brains, whereas glutamate/glutamine ratios were consistently decreased (with normal glutamine concentrations).

Amino Acids↗
PubMed1979

Brain neurotransmitter receptors in Friedreich's ataxia.

The binding of 3H-quinuclidinyl benzilate, a muscarinic cholinergic antagonist, of 3H-dihydroalprenolol, a beta adrenergic antagonist, and of 3H-flunitrazepam, a ligand which labels benzodiazepine receptors, was examined in several regions of control and Friedreich's ataxia (FA) brains. 3H-Quinuclidinyl benzilate binding appeared to increase in the inferior olivory nucleus, anterior and posterior cerebellar vermi but was unaltered in the dentate nucleus and cerebellar hemisphere of FA brain. The binding of 3H-dihydroalprenolol seemed to increase in the inferior olivary nucleus yet was not different from controls in the dentate nucleus, cerebellar hemisphere, anterior and posterior cerebellar vermi of FA brains. 3H-Flunitrazepam binding was slightly lowered in the inferior olivary and dentate nuclei but was unchanged in the other FA brain regions examined. The present study suggests possible trends in neurotransmitter receptor alterations in post-mortem brain tissue of FA patients.

Adult↗
PubMed1978

The effects of isoproterenol on taurine concentration in the rat heart.

Administration of the beta-agonist isoproterenol to rats caused a sharp increase in the influx rate of taurine into the heart, but had no effect on the rate of biosynthesis of taurine in the heart. Influx rates of other amino acids were also stimulated, the distribution ratios, (dpm/g heart)/(dpm/ml plasma), of beta-amino acids being 3--4 times higher than alpha-amino acids. The doses of isoproterenol employed induced cardiac hypertrophy, but the stimulation of taurine influx appeared to be an independent phenomenon, in that near maximum stimulation of influx was achieved prior to stimulation of ornithine decarboxylase activity. Reserpine treatment also produced stimulation of taurine influx with no effect on biosynthesis. These results indicate a close connection between increased sympathomimetic activity and increased influx of amino acids.

Amino Acids↗
PubMed1978

Isoproterenol-stimulated taurine influx in the perfused rat heart.

Taurine influx in the perfused rat heart was characterized and the effect of isoproterenol on this process determined. Hearts were perfused by the Langendorff technique with [3H]-taurine in a non-recirculating system. The rate of taurine influx was constant for at least 20 min and the process was saturable. A Km of 45 micron indicated that taurine influx is mediated by a high affinity transport system. Competition between taurine and beta-alanine, but not alpha-amino acids, for influx indicated that the transport sites are specific for beta-amino acids. Isoproterenol (4 X 10(-7) M) stimulated the rate of taurine influx, but propranolol (1 X 10(-8) M) blocked this stimulation. The enhancement of influx by isoproterenol was specific for beta-amino acids in that alpha-amino acid influx was not affected. Dibutyryl cyclic AMP (1 X 10(-3) M) and theophylline (1 X 10(-3) M) also stimulated taurine influx, whereas alterations in heart rate had no effect on the rate of taurine influx. The results are suggestive of a beta-adrenergically activated, cyclic AMP-mediated mechanism controlling isoproterenol-stimulated taurine influx.

Alanine↗
PubMed1977

Adrenergic stimulation of taurine transport by the heart.

A high-affinity transport system that is specific for beta-amino acids has been delineated in rat hearts. This system transports the cardiotonic sulfonic amino acid taurine. beta-Adrenergic stimulation increases the transport capacity without effect on alpha-amino acid uptake, as does stimulation with adenosine 3',5'-monophosphate or theophylline. The existence of such an uptake system for taurine in the heart accounts for the high intra- to extracellular concentration gradient that is maintained, and suggests that cardiac stress is associated with increased taurine uptake. This may explain why taurine is the only amino acid to be markedly elevated in congestive heart failure. Taurine is a modifier of calcium fluxes in the heart, as are beta-adrenergic agonists. The presence of this uptake system suggests a link between beta-adrenergic stimulation of calcium and taurine fluxes.

Alanine↗
PubMed1977

Hepatic veno-occlusive disease due to pyrrolizidine (Senecio) poisoning in Arizona.

An infant with documented hepatic veno-occlusive disease due to ingestion of pyrrolizidine alkaloids is presented. The alkaloids were ingested in the form of an herbal tea commonly used as a folk remedy among the Mexican-American population. Among these people, this herb is known as gordolobo yerba. The patient presented with acute hepatocellular disease and portal hypertension which progressed over 2 months to extensive hepatic fibrosis. Other potential causes of hepatic venous occlusion were absent.

Chemical and Drug Induced Liver Injury↗