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Biomedical subjects

G Rose

Publications and source records attributed to G Rose.

At least 181 records · Page 10Linked to original sources
PubMed1985

Structure and function of electrosensory neurons in the torus semicircularis of Eigenmannia: morphological correlates of phase and amplitude sensitivity.

Structure-function relations in the electrosensory system of Eigenmannia were examined by labeling physiologically characterized neurons of the dorsal torus semicircularis. The sensitivity of cells to modulations in amplitude (AMs) and modulations in differential phase was determined. Approximately half of the 48 cell types defined by Golgi studies (Carr, C.E., and L. Maler (1985) J. Comp. Neurol. 235: 207-240) were identified in this manner. The majority of the neurons located in laminae (8a, b, c, and d, and 9 exhibited sensitivity to differential phase. In laminae 5 and 7, however, in addition to neurons which were sensitive to differential phase, many cells were found that were purely AM sensitive. Differential phase sensitivity originates in the small cells of lamina 6 (Heiligenberg, W., and G. Rose (1985) J. Neurosci. 5: 515-531), the exclusive termination site of phase-coding afferents from the electrosensory lateral line lobe. Cells that had dendritic extensions into the neuropil of lamina 6 exhibited sensitivity to differential phase, whereas neurons lacking dendrites in this lamina were only excited by AMs. These findings support the notion of a relationship between the morphology and laminar position of a neuron and its function.

Animals↗
PubMed1984

Beta blockers after myocardial infarction: have trials changed practice?

A survey of British consultant cardiologists was carried out to elicit their current practices when prescribing long term beta blockers after myocardial infarction. Sixty (72%) of the respondents reported that they used beta blockers prophylactically even in the absence of any other indications; the details of their stated policies, however, varied considerably. The favourable evidence of clinical trials in this indication appears to have been assimilated into hospital practice.

Adrenergic beta-Antagonists↗
PubMed1984

The role of inhibitory mechanisms in hippocampal long-term potentiation.

The role of inhibitory processes in long-term potentiation (LTP) was investigated in hippocampal slices of the rat. GABAergic inhibition, tested by double shock experiments and by intracellular recording of inhibitory postsynaptic potentials, was not reduced in CA 1 pyramidal neurones after the induction of LTP. In cells recorded with caesium chloride-filled electrodes LTP could not be elicited. A reduction of intrinsic potassium-dependent inhibition may thus be responsible for LTP.

Afferent Pathways↗
PubMed1984

How well can we predict coronary heart disease? Findings in the United Kingdom Heart Disease Prevention Project.

The probability of myocardial infarction developing over five years in a group of middle aged men was predicted with knowledge of their ages, blood pressures, cholesterol concentrations, and smoking habits as recorded in an initial screening examination. Although the top 15% of the risk distribution predicted 115 (32%) of the subsequent cases of myocardial infarction, there was a considerable overlap in predicted risk between those subjects who did and those who did not go on to develop a myocardial infarction. Of the subjects in the top 15% of risk, only 72 (7%) of those initially free of coronary heart disease and 43 (22%) of those initially with coronary heart disease actually developed a myocardial infarction over the subsequent five years. Thus, although a group of subjects at high risk can be identified, among whom will be a high proportion of potential victims of heart attack, many subjects will be wrongly classified. These findings may explain part of the difficulty in persuading patients of the potential benefits of reducing risks and highlight the need for research to improve the prediction of the development of coronary heart disease.

Age Factors↗
PubMed1984

Inequalities in death--specific explanations of a general pattern?

In the Whitehall study, 17 530 civil servants were classified according to employment grade, and their mortality was recorded over 10 years. There was a steep inverse relation between grade and mortality. Compared with the highest grade (administrators), men in the lowest grade had 3 times the mortality rate from coronary heart disease, from a range of other causes, and from all causes combined. This is larger than the mortality differences, nationally, between classes I and V. Smoking and other coronary risk factors are more common in the lowest grades, but these differences account for only part of the mortality difference. The similarity of the risk gradient from a range of specific diseases could indicate the operation of factors affecting general susceptibility. The inverse relation between height and mortality suggests that factors operating from early life may influence adult death rates.

Adult↗
PubMed1984

Changes in the capacity of macrophages and T cells to produce interleukins during murine malaria infection.

Interleukin 1 (I1-1) produced by activated macrophages and interleukin 2 (I1-2) released by a subset of T lymphocytes upon antigen or mitogen stimulation are the soluble mediators involved in the mechanism of T-cell activation, proliferation, and differentiation. Since these T-cell responses are depressed during malaria infection, the capacity of macrophages to produce I1-1 following lipopolysaccharide (LPS) stimulation and that of lymphocytes to release I1-2 upon stimulation with concanavalin A (Con-A) in mice infected with either nonlethal Plasmodium yoelii (NLPY) or lethal Plasmodium berghei (PB) malaria parasites was analyzed. The results show that while adherent cells from spleen or peritoneal exudates of infected mice were able to produce I1-1, although to a different extent in the two infections, splenic lymphocytes were unable to produce I1-2, but capable of responding to it. This suggests that the diminished T-cell responses in malaria might be due to a defect of I1-2 synthesis.

Animals↗
PubMed1984

Differential effects of phencyclidine upon hippocampal complex-spike and theta neurons.

The effects of local application of phencyclidine (PCP) upon hippocampal CA1 neurons were investigated in urethane-anesthetized rats. Hippocampal neurons were classified on the basis of extracellularly recorded action potential duration as either complex-spike or theta cells prior to PCP administration. PCP depressed spontaneous firing of 46 of 48 complex-spike cells, but excited 12 of 13 theta neurons. This result demonstrates that hippocampal complex-spike and theta neurons may be differentiated of theta neurons were greatly attenuated or absent in rats pretreated with DSP4, a neurotoxin which selectively destroys noradrenergic pathways. This latter finding lends additional support to the hypothesis that the effects of locally applied PCP are mediated via noradrenergic mechanisms.

Animals↗
PubMed1984

International trends in cardiovascular disease--implications for prevention and treatment.

Stroke mortality is declining fast in many countries (this decline being due, in part, to treatment), with implications for medical care and for coronary disease incidence, but in some European countries rates are rising. Coronary mortality is decreasing fast in some countries, probably because of a fall in incidence; dietary and other life-style changes are likely to be involved, but lack of systematic monitoring inhibits firm conclusions. In other countries with comparable medical care the rates have not declined, and in eastern Europe and sections of developing populations they are rising fast. Some implications are discussed.

Australia↗
PubMed1984

Beta-blockers after myocardial infarction.

Excellent recent trials have demonstrated beyond reasonable doubt that beta-blockade started during convalescence from confirmed myocardial infarction reduces mortality in the next year or two by about a quarter. Similar confidence does not extend to the mechanisms of action, choice of drug, defining treatment criteria in relation to severity and age, or to the duration of treatment.

Adrenergic beta-Antagonists↗
PubMed1984

Blood pressure and its correlates in an African tribe in urban and rural environments.

As part of a longitudinal study of migrants who move from a subsistence farming rural society to Nairobi, blood pressures and associated factors were measured in cross sectional studies of members of the Luo tribe in their traditional rural environment and in the urban environment of Nairobi. Blood pressures in Nairobi correlated with duration of urban residence. In the rural area men showed a negligible rise in blood pressure with age, and both sexes showed a significantly smaller rise than in the urban area. Although mean weights of the rural group were smaller, this did not account for all the urban/rural differences in blood pressures. Nevertheless, mean urinary sodium concentration and sodium ratios (sodium/potassium and sodium/creatinine) were significantly higher in the urban group whereas mean urinary potassium concentration and potassium/creatinine ratio were significantly lower. Perhaps the ratio of sodium to potassium in the diet contributes to the different blood pressure profiles of these two populations.

Adult↗
PubMed1984

Renal transplant rejection: sonographic evaluation in children.

The ability to detect renal rejection sonographically was studied in 42 pediatric renal transplant patients over a 33-month period. Sonography was not helpful in detecting rejection when the donor was less than five years of age. When the donor was over five years of age, a combination of sonographic findings allowed detection of rejection with a greater specificity than has been reported previously. The combination of three or more of the sonographic findings (increased renal volume 30% over the baseline value; enlarged, broadened, rectangular medullary pyramids [rays]; a reduction or absence of the central sinus echoes, and altered echogenicity in the renal parenchyma) indicated rejection with 97% specificity and 58% sensitivity. Radionuclide imaging with Tc-99m DTPA gave approximately the same sensitivity (60%) but was less specific (88%). By excluding rejection with the absence of the sonographic findings, it was possible to suggest acute tubular necrosis in some patients. It was also possible to detect the complications of renal transplantation, but sonography did not detect small ruptures of the kidney as a part of the rejection phenomenon.

Adolescent↗
PubMed1983

Carbon monoxide yield of cigarettes and its relation to cardiorespiratory disease.

Estimates of the carbon monoxide yield of their cigarettes have been obtained for 4910 smokers (68% of all smokers) in the Whitehall study of men aged 40 to 64. In the 10 years after examination 635 men died. When men smoking cigarettes with high carbon monoxide yield were compared with those smoking cigarettes with a low yield, and after adjusting for age, employment grade, amount smoked, and tar yield, the risk of death was 32% lower for coronary heart disease, 49% higher for lung cancer, and 10% lower for total mortality; these differences were not statistically significant. Among men who said that they inhaled the risk of fatal coronary heart disease was 51% lower in the high carbon monoxide group (p less than 0.01), while the risk of lung cancer was 75% higher. These results provide no evidence that a smoker can reduce his risk of death by smoking a brand with a low carbon monoxide yield; he might even increase it. The complex interactions between characteristics of the smoker, smoking behaviour, constituents of tobacco smoke, and health are again demonstrated.

Adult↗
PubMed1983

Mortality from coronary heart disease and stroke in relation to degree of glycaemia: the Whitehall study.

In the Whitehall study of 18 403 male civil servants aged 40-64 years the 10 year mortality rates from coronary heart disease and stroke showed a non-linear relation to two hour blood glucose values, with a significantly increased risk for glucose intolerant subjects with concentrations above the 95th centile point (5.4-11.0 mmol/l; 96-199 mg/100 ml) and for diabetics (blood glucose greater than or equal to 11.1 mmol/l; greater than or equal to 200 mg/100 ml). Multiple logistic analysis showed that between one half and three quarters of the relative risks for deaths from coronary heart disease and stroke were "unexplained" by between group differences in risk factors such as age, blood pressure, obesity, smoking, cholesterol concentration, and electrocardiographic abnormalities. Within the glucose intolerant and diabetic groups the risk factors most strongly related to subsequent death from coronary heart disease were age and blood pressure, with less consistent relations for smoking, cholesterol concentration, and obesity. This study confirms the importance of hypertension as a cardiovascular risk factor in groups with glucose intolerance and diabetes, and this may have important preventive implications.

Adult↗
PubMed1983

UK heart disease prevention project: incidence and mortality results.

Results are presented for the UK centre of the WHO European Collaborative Trial in the Multifactorial Prevention of Coronary Heart Disease (CHD). 18 210 men took part, aged 40 to 59; they were employed in 24 factories, which formed the allocation units for a randomised controlled trial lasting 5-6 years. Intervention comprised advice on cholesterol-lowering diet, smoking cessation, weight control, exercise, and treatment of hypertension. Advice was given mainly through factory medical departments, the staff being supplemented a little by a visiting central team. Self-reported cigarette smoking was moderately reduced, but changes in other risk factors were small and not well sustained. There was no clear effect on hard CHD end-points (coronary deaths and myocardial infarction) or on all-causes mortality. However, there was a 36% reduction in the rate at which intervention subjects reported ill with other CHD (principally angina) during the study, and at the end fewer intervention men gave positive responses to a self-administered questionnaire on angina and chest pain. These apparent benefits were not substantiated by electrocardiographic evidence, suggesting that participation in a heart disease prevention campaign may bias reporting of symptoms. Experience in other centres of the Collaborative Trial, however, suggests that more effective risk factor control does reduce CHD incidence and mortality. This implies that for the UK the problem is to find means of enhancing the acceptance of health advice.

Adult↗
PubMed1983

Dentate granule cells in the rat hippocampal formation have the behavioral characteristics of theta neurons.

Recordings were made from the dentate gyrus granule cell layer of freely-moving rats. The neurons recorded from the layer were divisible into 3 classes using a combination of electrophysiological and behavioral criteria; the duration of the extracellularly recorded unfiltered action potential provided the most reliable means of differentiating between cell types. Class I and class II neurons always fired in short duration single action potentials, while class III neurons had broader waveforms and occasionally were observed to fire complex spikes. As the most obvious behavioral correlate of class I and class II neurons was movement of the rat, these cells correspond to the theta cells of Ranck. Class III neurons for which a behavioral correlate was observed had the characteristics of the place cells described by O'Keefe. The neurons of classes I and II comprised 89% (56 of 63) of the total population sampled in the granule cell layer. Most of these neurons (49 of 56) discharged at short latency in response to a stimulus delivered via the perforant pathway; in contrast, none of the class III neurons observed were activated in this way. Horseradish peroxidase or Fast Green dye ejection through glass microelectrodes recording class I cell activity in urethane-anesthetized animals revealed the electrode tip to be in the granule cell layer in 27 of 27 cases. Six single class I neurons were also antidromically activated by a stimulus from an electrode placed in the hippocampal mossy fibers, and collision testing was successful in all cases. It is concluded that the dentate granule cells are theta cells.

Animals↗
PubMed1983

Temporal selectivity in the central auditory system of the leopard frog.

Amplitude modulation is a predominant temporal feature in many vocal signals. The leopard frog, Rana pipiens, has a class of neurons in the central auditory system that respond selectively to particular rates of amplitude modulation; these neurons can be characterized by a temporal tuning curve. Such selectivity is absent in the peripheral auditory system. This type of transformation may be fundamental in processing temporal information in the vertebrate sensory nervous system.

Animal Communication↗
PubMed1983

Diabetes, hyperglycemia, and coronary heart disease.

An international collaborative group examined the relation between asymptomatic hyperglycemia and coronary heart disease (CHD). After excluding clinically diagnosed diabetes and treated hypertensives, there were 48,912 men aged 35-64 in the study population. Post-load circulating glucose correlated with age, relative weight, and systolic blood pressure. The prevalence on ECG of S-T/T findings, but not of Q/QS items, was higher in the top quintile of glycemia. For CHD mortality there was no consistent, strong, or independent association with glycemia. In the Whitehall Study (the largest), it appeared that there was a threshold effect, CHD mortality being about twice as high above the 95th percentile of glycemia. Stroke mortality was increased to a similar extent.

Adult↗