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Biomedical subjects

J R Thompson

Publications and source records attributed to J R Thompson.

At least 199 records · Page 11Linked to original sources
PubMed1989

The association between visual impairment and mortality in elderly people.

By linking together the results from two surveys of elderly people in an English community it has been possible to consider visual impairment as a possible risk factor for mortality in people aged 75 years and over. Although minor degrees of visual impairment are associated with an increased mortality rate, blind people survive better than those with less serious visual impairments. Associations are considered between visual impairment and other known risk factors for mortality in the elderly. Visual impairment is shown to be associated with degree of social contact, whether a person lives alone, dementia score, physical activity score and number of unmet needs.

Aged↗
PubMed1989

Eyelid opening in preterm neonates.

The frequency and patterns of eyelid opening were examined in a group of neonates (gestational age 24-35 weeks). Observations were spread over the 24 hour period to obtain a complete pattern of events. Mean eyelid closure was 74%. When babies were grouped by gestational age, however, differences became apparent, babies of less than 26 weeks having their eyes shut for only 55% of observations compared with 93% at 28 weeks. Trend analysis confirmed that eyelid closure reached a peak at 28 weeks. Neonates exposed to a day/night regimen, opened their eyes significantly more than those exposed to continuous illumination. We suggest that frequency of eyelid opening may be related both to the infant's developmental state (postmenstrual age) and the illumination of the neonatal unit. Frequency of eyelid opening should therefore be considered when calculating the ocular light exposure of preterm neonates.

Aging↗
PubMed1989

The demand incidence of cataract in Asian immigrants to Britain and their descendants.

Cataract is known to be more common in India than it is in the industrialised world, but there is little evidence to show whether people emigrating from India will continue to have a high incidence of the disease. Data have been collected from the outpatient clinics of a hospital in Leicester, England, that suggest that for people aged over 45 the demand incidence of cataract is more than five times higher in people of Indian descent than it is in the indigenous population. As well as measuring the demand incidence of cataract in Leicester's two main racial groups the data are used to investigate other risk factors. For both communities the demand incidence of cataract is significantly higher in women than in men, and it is significantly higher in people of Indian descent who emigrated directly from India than in those who emigrated from East Africa. Religious subgroups within the immigrant community also show small differences in their demand incidence. The possibility that these differences are linked to diet is considered.

Adolescent↗
PubMed1989

Recent trends in the registration of blindness and partial sight in Leicestershire.

A study is reported of all new registrations for blindness and partial sight in the county of Leicestershire, England, for the years 1965, 1975, and 1985. The number of new registrations for blindness has risen considerably over this period, but the increase is shown to be attributable to changes in the age structure of the population and under-registration in 1965. The number of new registrations for partial sight has also increased over the study period but by significantly more than would be expected, even after changes in the population structure are allowed for. The registration rates for Leicestershire when analysed by age, sex, and cause are shown to be broadly in line with available national figures. Registration rates for macular degeneration and glaucoma are increasing in both males and females, and rates for cataract are at a significantly higher level for women than for men.

Adolescent↗
PubMed1989

Pediatric choroid plexus neoplasms: MR, CT, and pathologic correlation.

Choroid plexus papillomas are rare, constituting approximately 0.5% of all intracranial neoplasms. Four benign choroid plexus papillomas and one choroid plexus carcinoma were retrospectively reviewed in patients aged 4-20 months who had been examined with magnetic resonance (MR) imaging with a field strength of 0.5 T or 1.0 T and with computed tomography (CT) before and after the administration of contrast material. In general, the tumors were of intermediate signal intensity on T1-weighted images and of either intermediate or increased signal intensity (T2 lengthening) with T2 weighting. All demonstrated variable areas of internal signal void interpreted as signifying regional blood flow, calcification, or old hemorrhage. CT findings included relatively uniform contrast enhancement. Microscopic pathologic changes of the benign lesions mimicked the appearance of normal choroid plexus and confirmed the highly vascular nature of these tumors. MR imaging, with its high-resolution multiplanar techniques, offers direct visualization of these lesions in relation to normal anatomy and better discrimination and confirmation of their intraventricular location, facilitating surgery and postoperative follow-up.

Carcinoma↗
PubMed1989

Antagonistic effect of idazoxan on xylazine-induced central nervous system depression and bradycardia in calves.

Two doses of an alpha 2-adrenoreceptor antagonist, idazoxan, were administered to reverse the CNS depressant and bradycardia effects of xylazine in calves. Once a week for 3 weeks, each of 6 calves were administered IV one treatment of: (1) 0.2 mg of xylazine/kg of body weight followed in 10 minutes by 1 ml of 0.9% NaCl, (2) 0.2 mg of xylazine/kg followed in 10 minutes by 10 micrograms of idazoxan/kg, or (3) 0.2 mg of xylazine/kg followed in 10 minutes by 30 micrograms of idazoxan/kg. The order of the 3 treatments in each calf was selected at random. Xylazine alone caused lateral recumbency for 27.2 +/- 3.0 minutes (mean +/- SEM). Idazoxan administered at dosages of 10 and 30 micrograms/kg shortened xylazine-induced lateral recumbency to 11.5 +/- 0.8 and 10.3 +/- 0.2 minutes, respectively. Calves given xylazine alone stood at greater than 60 minutes after the onset of recumbency. Idazoxan given at dosages of 10 and 30 micrograms/kg shortened the time to standing to 16.8 +/- 1.7 and 11.3 +/- 0.2 minutes, respectively. Idazoxan given at a dosage of 30 micrograms/kg also reversed xylazine-induced bradycardia. Results indicated that idazoxan should be a useful antidote for xylazine overdose in cattle.

Animals↗
PubMed1988

The effect of ketone bodies on alanine and glutamine metabolism in isolated skeletal muscle from the fasted chick.

The effects of ketone bodies on the metabolism of alanine and glutamine were studied in isolated extensor digitorum communis (EDC) muscles from 24 h-fasted chicks. (1) Acetoacetate and DL-beta-hydroxybutyrate (4 mM) markedly inhibit branched-chain amino acid (BCAA) transamination and alanine formation. (2) Ketone bodies (1 and 4 mM) increase the intracellular concentration and release of glutamate and glutamine, suggesting that inhibition of BCAA transamination does not limit intracellular availability of glutamate for alanine synthesis. (3) Ketone bodies (1 and 4 mM) do not affect glucose uptake by muscles, but decrease the rate of glycolysis as well as the intracellular concentration and release of pyruvate in muscles. (4) Addition of 12 mM-glucose increases the formation of alanine in muscles incubated in the absence of ketone bodies, but has no effect in muscles incubated in the presence of 4 mM ketone bodies. (5) Addition of 5 mM-pyruvate to the media prevents the inhibiting effect of ketone bodies on BCAA transamination and alanine synthesis. These results suggest that ketone bodies decrease alanine synthesis by limiting the intracellular availability of pyruvate, owing to inhibition of glycolysis, and inhibit BCAA transamination by decreasing the intracellular concentration of amino-group acceptors such as pyruvate in EDC muscles from fasted chicks.

Alanine↗
PubMed1988

Sequence and genetic analysis of a dispensible 189 nucleotide snRNA from Saccharomyces cerevisiae.

The structure of a Saccharomyces cerevisiae gene that encodes a small nuclear RNA (snRNA) of 189 nucleotides is described. This gene, designated SNR189, is located 400 base pairs upstream of the CRY1 gene on yeast chromosome III. Gene replacement analysis revealed the SNR189 gene to be dispensable for growth under a variety of culture conditions. The snR189 sequence lacks homology with other sequenced yeast or metazoan snRNAs.

Base Sequence↗
PubMed1988

CT and angiographic correlation of severe neurological disease in toxemia of pregnancy.

Two patients with severe cerebral symptoms of toxemia of pregnancy were examined using computed tomography (CT) and angiography. CT disclosed extensive areas of low attenuation within the cerebral hemispheres. Angiography revealed constriction and narrowing of proximal and peripheral vessels suggesting vasculitis with extensive areas of impaired regional cerebral blood flow. A review of the known pathology and the theories regarding the pathophysiology of the cerebral effects of toxemia is presented.

Adult↗
PubMed1988

Effect of pyruvate, octanoate and glucose on leucine degradation in skeletal muscle from fed and fasted chicks.

1. Pyruvate at 5 mM decreased the rate of leucine oxidative decarboxylation and increased the rate of 2-oxoisocaproate production in extensor digitorum communis (EDC) muscles from both fed and 24-hr fasted chicks. Pyruvate at 5 mM increased the net rate of leucine transamination in EDC muscle from fed chicks and had no effect in EDC muscles from 24-hr fasted chicks. 2. Octanoate at 0.2 and 1 mM markedly increased the rates of net leucine transamination, leucine oxidative decarboxylation and oxidation of decarboxylated leucine carbons 2-6 in EDC muscles from fed chicks, but had no effect on these parameters of leucine degradation in muscles from 24-hr fasted chicks. 3. Glucose at 5 and 12 mM decreased the rates of leucine oxidative decarboxylation and oxidation of decarboxylated leucine carbons 2-6, and increased the net rate of 2-oxoisocaproate production as compared to control (no glucose) group in muscles from fed chicks. Glucose had no effect on these parameters of leucine degradation in muscles from 24-hr fasted chicks.

Animals↗
PubMed1988

Effects of nursery illumination on frequency of eyelid opening and state in preterm neonates.

The behaviour of a group of premature neonates was observed under three conditions of ambient illumination defined as either DARK, LIGHT or BRIGHT (mean intensities: 0.9, 109 and 1370 lux). Trends in the data suggested that increasing the level of illumination resulted in a reduction in the proportion of time spent with eyelids open and of the amount of time spent in awake states. However, these effects were small and in most cases failed to attain statistical significance. Sudden offset of light did however produce a transitory increase in eyelid opening for a period of approximately 60 s that appeared to be unaccompanied by any change of state (P less than 0.001). Irrespective of illumination condition, the infants' behaviour was characterized by prolonged periods of eyelid closure which were significantly greater for the lower eye (in mattress contact, mean lid closure = 96.2%) compared to the upper eye (no mattress contact, mean lid closure = 88.25%). The prolonged occurrences of eyelid closure are discussed in relation to visual development and phototoxicity.

Arousal↗
PubMed1988

The prevalence of retinopathy in the insulin-requiring diabetic patients of an English country town.

A population-based survey of the insulin-requiring diabetics of a representative population was carried out. The overall prevalence of diabetes was 10.9/1000, that of insulin-requiring diabetes 4.1/1000. No retinopathy was found in 59%, background retinopathy was found in 33% and proliferative and advanced disease in 8%, diabetic maculopathy was present in 6.8% and the prevalence of potentially treatable disease undetected was 7.6%. Significant risk factors identified for retinopathy were increased duration of diabetes and elevated diastolic blood pressure, those for maculopathy an increased age at examination and onset of diabetes and an elevated systolic blood pressure.

Adolescent↗
PubMed1988

Ribosomal protein synthesis is not regulated at the translational level in Saccharomyces cerevisiae: balanced accumulation of ribosomal proteins L16 and rp59 is mediated by turnover of excess protein.

We have investigated the mechanisms whereby equimolar quantities of ribosomal proteins accumulate and assemble into ribosomes of the yeast Saccharomyces cerevisiae. Extra copies of the cry1 or RPL16 genes encoding ribosomal proteins rp59 or L16 were introduced into yeast by transformation. Excess cry1 or RPL16 mRNA accumulated in polyribosomes in these cells and was translated at wild-type rates into rp59 or L16 proteins. These excess proteins were degraded until their levels reached those of other ribosomal proteins. Identical results were obtained when the transcription of RPL16A was rapidly induced using GAL1-RPL16A promoter fusions, including a construct in which the entire RPL16A 5'-noncoding region was replaced with the GAL1 leader sequence. Our results indicate that posttranscriptional expression of the cry1 and RPL16 genes is regulated by turnover of excess proteins rather than autogenous regulation of mRNA splicing or translation. The turnover of excess rp59 or L16 is not affected directly by mutations that inactivate vacuolar hydrolases.

Gene Expression Regulation↗
PubMed1988

Grating and recognition acuities of young amblyopes.

The visual acuities of 36 young amblyopes were determined by (a) conventional recognition tests (near and distance) and (b) an adapted grating acuity card procedure. Considerable agreement between the estimates of acuity obtained with each method was demonstrated, which was generally less than, or equal to, the mean difference between adjacent Snellen lines (4.5 c deg-1). Estimates of grating acuity obtained with vertical gratings did not differ significantly from those obtained with horizontal gratings. There was no difference between the subjects' ability to detect the grating (acuity) and accurately to discriminate target orientation (horizontal or vertical). The results of the experiment are discussed in relation to previous findings of a discrepancy between grating and recognition acuities in amblyopia, and the clinical use of the acuity card procedure.

Amblyopia↗
PubMed1988

Arachidonic acid, prostaglandin E2 and F2 alpha inhibit leucine degradation in chick skeletal muscle.

Arachidonic acid (5 microM), prostaglandin E2 (0.28 microM) and F2 alpha (14 microM) inhibited (P less than 0.01) the rates of net leucine transamination, leucine oxidative decarboxylation and total CO2 production from leucine in extensor digitorum communis muscles from fed ten-day-old chicks. Indomethacin (50 microM) markedly inhibited (P less than 0.01) the rate of PGE2 production in the presence of 5 microM arachidonic acid and prevented the inhibition of leucine degradation by arachidonic acid in skeletal muscle. These results demonstrate that the actions of arachidonic acid on leucine degradation in chick skeletal muscle are mediated by metabolites generated via the cyclooxygenase pathway and that prostaglandins may play a role in the regulation of leucine degradation in skeletal muscle.

Animals↗