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Biomedical subjects

G Dean

Publications and source records attributed to G Dean.

At least 73 records · Page 4Linked to original sources
PubMed1986

Interventricular delay in severe aortic stenosis recognized by gated radionuclear blood pool scanning.

Twenty-four patients referred for cardiac catheterization for suspected aortic stenosis were investigated by equilibrium gated blood pool study. From the time-activity curves, end systole for each ventricle was determined and the delay between the two was calculated. The patients were divided into three groups according to their calculated aortic valve area. The mean delay in a control group of 20 normal subjects was 6 +/- 13 msec (mean +/- standard deviation). In group I (aortic valve area greater than 0.75 cm2) the delay was 16 +/- 25 msec (p = NS compared to controls); in group II (aortic valve area 0.5 to 0.75 cm2) the delay was 28 +/- 27 msec (p less than 0.01); and in group III (aortic valve area less than 0.5 cm2) the delay was 60 +/- 28 msec (p less than 0.001). Ten patients were restudied after valve replacement; their mean delay decreased markedly from 48 +/- 19 to 5 +/- 26 msec (p less than 0.001). Thus, this method appears to identify patients with severe aortic stenosis and may therefore be a useful adjunct to the noninvasive assessment of this disorder both before and after surgery.

Adult↗
PubMed1986

A further study on the prevalence of multiple sclerosis in Sicily: Caltanissetta city.

The prevalence of probable multiple sclerosis (MS) in Caltanissetta city, Sicily, is at least 51 per 100,000. If possible multiple sclerosis patients are included, it is 54 per 100,000. This value is similar to that found in other cities in Sicily: Enna, Monreale and Agrigento. The high prevalence of multiple sclerosis in Caltanissetta confirms the previous data on Sicily and emphasises the importance of small population studies in the epidemiology of MS.

Adolescent↗
PubMed1985

To tell or not to tell the diagnosis of multiple sclerosis.

167 patients disabled by multiple sclerosis were interviewed to ascertain their views about being told the name of the disease causing their disability. 30 were ignorant of the nature of their disease. 83% favoured knowing the diagnosis, 13% were indifferent, and less than 4% preferred not to know the diagnosis. Almost a quarter of the patients had discovered the diagnosis for themselves. All the respondents thought that the consultant was the person who should convey the diagnosis of multiple sclerosis.

Attitude to Health↗
PubMed1985

Multiple sclerosis in research workers studying swayback in lambs: an updated report.

Four out of seven research workers into swayback disease, a neurological disease of lambs, developed symptoms and signs of multiple sclerosis, and were reported in 1947. A further worker later joined the group. All of the original seven have died and two at necropsy had multiple areas of demyelination in the brain and spinal cord. The chance of four or more out of a random group of eight men developing multiple sclerosis is about one in a thousand million. Multiple sclerosis has not occurred in other workers on swayback disease elsewhere.

Adult↗
PubMed1984

Suicide and self-poisoning in three countries--a study from Ireland, England and Wales, and Denmark.

Because it has been suggested that both the frequency of deliberate self-poisoning and the characteristics of those who self-poison differ between Ireland, and England and Wales on the one hand and Denmark on the other we have examined self-poisoning rates and suicide rates in these three countries. Higher self-poisoning rates were found for England and Wales than for the other two countries below age 35. After this age self-poisoning rates decline in both England and Ireland but female rates continue to rise in Denmark up to age 45. Danish suicide rates are conspicuously higher than those of both England and Wales, and Ireland. Because combined death rates for suicide, undetermined and accidental deaths diminish but do not remove the differences between countries it is suggested that the Danish suicide death rate reflects a genuinely higher rate of suicide in that country.

Adolescent↗
PubMed1984

Multiple sclerosis in the Republic of San Marino.

Previous studies on the prevalence of multiple sclerosis in Italy have grossly underestimated the prevalence of the disease. The prevalence in the Republic of San Marino (near Rimini), in Sicily, and no doubt in the rest of Italy, is of the same order of magnitude as in Europe--that is, 40-60/100 000. The contrast of this with the very low prevalence in Malta (only 60 miles (96 km) away from Sicily) of 4/100 000 should provide a clue to the genetic and environmental factors responsible for multiple sclerosis.

Adult↗
PubMed1983

Need for and use of social and health services by multiple sclerosis patients living at home in England.

200 disabled multiple sclerosis patients living at home in England were interviewed to discover to what extent they were receiving the social and health benefits to which they were entitled. Many patients were ignorant of their entitlements, and there were major deficiencies in their receipt of cash benefits, job retraining, rehousing and home alterations, help in the home, and telephones, cars, and radio and television receivers. Social-worker visits were infrequent and ineffective. No single person is responsible for informing patients about benefits and helping to secure them. A multiple sclerosis register is recommended, together with automatic referral of those listed to social workers. The only major criticism of medical care was that the diagnosis should be revealed to the patient earlier and more information on the disorder should be provided. More frequent contact with multiple sclerosis patients by ancillary health workers (physiotherapists and health visitors) is needed.

Consumer Behavior↗
PubMed1983

Localization of 2',3'-cyclic nucleotide-3'-phosphohydrolase within the vertebrate retina.

Histochemical and immunochemical techniques are used to locate 2',3'-cyclic nucleotide-3'-phosphohydrolase (2',3'-cNMP-3'ase) within cells of the vertebrate retina. A new histochemical method is described which links the hydrolysis of 2',3'-cNADP to the formation of a reduced, insoluble tetrazolium formazan. Photoreceptors from fish, bovine, and rat retinas are stained by this procedure. The reaction is blocked by 2'-AMP, a known inhibitor of 2',3'-cNMP-3'ase. Rabbit antibodies prepared against 2',3'-cNMP-3'ase from bovine brain are found to cross-react with bovine and rat retinal enzymes. Peroxidase-labeled antibody shows by light microscopy the greatest staining along the inner segments of the photoreceptors. Electron microscopy of the same preparations confirms binding to the plasma membrane of the inner segments of both rods and cones. Retinal 2',3'-cNMP-3'ase is thus predominantly associated with the photoreceptors, suggesting some role for 2',3'-cyclic nucleotides as substrates in visual function.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1983

Secretion of newly taken up ascorbic acid by adrenomedullary chromaffin cells originates from a compartment different from the catecholamine storage vesicle.

Chromaffin cells in primary culture take up [14C]ascorbic acid from the incubation medium. Cells, stimulated immediately after a short labeling period with [14C]ascorbate, secrete ascorbic acid concomitantly with catecholamines (CA) through a nicotinic receptor-mediated Ca2+-dependent process. A proportional release of CA and [14C]ascorbic acid was observed through a large range of secretion rates obtained by varying the concentration of nicotine or by changing the concentrations of Ca2+ and Na+ in the external medium. However, under the same conditions of stimulation, different cell preparations secrete 2-10 times more CA than [14C]ascorbate (as percentage of cell content). Furthermore, a different time course of secretion was observed for CA and [14C]ascorbate for each of several secretagogues. In addition, Ba2+ is a much more potent stimulus for CA secretion than for secretion of [14C]ascorbate, and Ca2+ channel blockers are more potent in inhibiting CA secretion than [14C]ascorbate secretion. These data suggested the possibility that newly taken up ascorbate was being secreted from a compartment altogether distinct from the chromaffin vesicle. This hypothesis was confirmed by subcellular distribution studies, where only a minor fraction of newly taken up [14C]ascorbate was found in the vesicular fraction (P2) from homogenates of chromaffin cells prepared after a short incubation with [14C]ascorbate. However, the subcellular distribution of [14C]ascorbate follows that of endogenous ascorbate when a short pulse with the label is chased by a prolonged equilibration period in the absence of ascorbate, indicating that a transfer has occurred from the extravesicular compartment(s) to the CA storage organelle. Endogenous ascorbate, which is found both inside and outside the chromaffin vesicle, was also found to be secreted from chromaffin cells, indicating that ascorbic acid could be released simultaneously from two different subcellular compartments.

Adrenal Medulla↗
PubMed1982

Secretion of newly taken-up ascorbic acid by adrenomedullary chromaffin cells.

Primary cultures of bovine adrenomedullary cells accumulate carbon-14-labeled ascorbic acid through a saturable and energy-dependent process. The newly taken-up ascorbate is released concomitantly with catecholamines upon stimulation of chromaffin cell secretion. The release of ascorbate is Ca2+-dependent and mediated through activation of nicotinic receptors. These results indicate that exogenous ascorbate taken up into chromaffin cells is incorporated in situ into a secretable compartment, probably the catecholamine-containing chromaffin vesicles.

Adrenal Medulla↗
PubMed1982

Tissue, subcellular, and submitochondrial distributions of semidehydroascorbate reductase: possible role of semidehydroascorbate reductase in cofactor regeneration.

The immediate product of ascorbate oxidation coupled to dopamine-beta-hydroxylation is not dehydroascorbate, as previously thought, but rather semidehydroascorbate. For this reason, the possible participation of the enzyme semidehydroascorbate reductase (SDR) in cofactor regeneration was investigated. In the adrenal medulla, the primary subcellular localization of this reductase was shown to be in the mitochondria. Submitochondrial fractionation studies indicated that SDR is an outer membrane protein. Thus, although dopamine-beta-hydroxylase and SDR have different subcellular localizations, a physiological role for SDR in beta-hydroxylation still appears plausible through reduction of cytosolic semidehydroascorbate. The specific activities of SDR in various rat and guinea pig tissues appear to parallel their ascorbate contents, suggesting a similar participation of SDR in ascorbate metabolism in other tissues.

Adrenal Cortex↗