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Biomedical subjects

J H Fuller

Publications and source records attributed to J H Fuller.

At least 19 recordsLinked to original sources
PubMed1992

Head movement propensity.

In studies of human eye-head coordinated saccadic gaze shifts, different laboratories have found greatly different magnitudes of head movements for a given amplitude of gaze shift (head movement gain). The present study was conducted to examine why, and to quantify volitional head movements. Fixation/target lights were located at 20 degrees and 40 degrees on either side of a central light. There were two tasks or modes. In the non-aligned mode, gaze fixation (first light) was followed by a gaze step to the target (second light) accurately and quickly. In the head-aligned mode, the head was aligned within 3 degrees of the first fixation light (i.e., initial starting position) before the step sequence began. In both non-aligned and head-aligned modes, subject instructions pertaining to the second target light concerned only gaze; there was no requisite head position. The head movement propensity of nine subjects was ranked according to the mean gain (head/target amplitude) of two 40 degree jumps (0-40 degrees and -20 to +20 degrees) in the non-aligned mode. This ranking method clearly identified extreme head-movers and non-movers. The moderate movers were further characterized by three additional criteria, derived by comparing the gains in different jumps, which varied in starting position and amplitude. First, when the two 40 degree jumps were compared, typically the gain of non-movers was less in the symmetric jump (-20 to +20 degrees) with the gain of the head-movers was greater in the symmetric jump. Second, in the head-aligned mode the gain of non-movers progressively increased when the starting position was progressively moved eccentrically, whereas the gain of head-movers increased only slightly, if at all. Third, when the gains of two symmetric (40 degrees and 80 degrees) jumps were compared, the head-movers consistently had opposite trends from non-movers. These three comparative criteria and the initial criterion together define head movement propensity. To explain the above observations, three effects are proposed. First, a "midline-attraction" effect causes resistance to movement away from the midline in non-movers and an increase in movement amplitude if the jump starts eccentrically. Second, a "resetting" effect occurs when the eccentricity of the jump is varied; the stopping position is reset closer to the target. Third, an "awareness/arousal" effect increases the gain in the head-aligned mode due to the intrinsic nature of the alignment procedure.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Recent trends in diabetes mortality in England and Wales.

Trends in diabetes-related mortality in England and Wales between 1975-6 and 1985-6, and regional and ethnic differences in diabetes-related mortality in 1985-6, have been examined. Data from death certificates mentioning diabetes in 1975-6 were compared with those for 1985-6 for different age groups. Data for 1985-6 were also analysed for different regions of England and Wales, and for country of birth. Between 1975-6 and 1985-6, the age-standardized rate of mentioning diabetes rose by 2.7% (95% confidence interval 1.4%, 4.1%) in men of all ages, and fell by 11.7% (10.6, 12.8) in women of all ages. By contrast, the rate of mentioning diabetes in those below 45 years fell by 30.7% (23.0, 37.7) in men and by 26.7% (16.5, 35.6) in women. Deaths in which the underlying cause was ischaemic heart disease (IHD), and where diabetes was also mentioned on the death certificate, rose by 14.4% (11.5, 16.8) in men and did not change significantly in women of all ages, but fell by 18.4% (-35.1, +2.6) in men, and 23.5% (-49.1, +15.2) in women below age 45. This was less favourable than the trend in the general population, where IHD mortality fell by 9.7% in men and 8.3% in women of all ages, and by 31.1% (28.6, 33.5) in men and 40.5% (35.0, 45.5) in women under 45 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1992

Recent developments in diabetes epidemiology in Europe.

Recent developments in diabetes epidemiology in Europe have included the completion of the European Community sponsored Concerted Action on the Epidemiology and Prevention of Diabetes (Eurodiab), further studies of diabetes and coronary heart disease prevalence in ethnic minority groups in the United Kingdom, and studies of the effect of poor fetal and early post-natal nutrition on the risk of developing non-insulin dependent diabetes (NIDDM). The EURODIAB Concerted Action Programme has provided valuable new information on the incidence of insulin-dependent diabetes mellitus (IDDM) throughout Europe and has drawn attention to an unexpectedly high incidence in Sardinia. In the EURODIAB IDDM complications study, the prevalence of both large- and small-vessel complications of diabetes has been examined, using standardized methods, in 3,279 IDDM patients from 31 centres throughout Europe. The data on risk factors for complications obtained from this study will have significant health policy implications for diabetes in Europe which will be utilized by the current St. Vincent Declaration Action Programme for Diabetes Care and Research in Europe. In another part of the EURODIAB Concerted Action Programme, important information has been obtained on the validity of routinely-collected diabetes health information, such as mortality statistics based on death certificates, and estimates of diabetes prevalence obtained from drug-utilization data.

Adolescent↗
PubMed1979

Haemostatic variables associated with diabetes and its complications.

To study the possible role of an "increased thrombotic tendency" in the vascular complications of diabetes several tests of haemostatic function were carried out on 91 men and 63 women with diabetes aged 35-54 years and the results compared with findings in 686 men and 393 women of the same age in the Northwick Park Heart Study. Mean values for factors VII and X, fibrinogen, and platelet adhesiveness were higher in the diabetics, but mean fibrinolytic activity and whole blood platelet counts were lower. Antithrombin III values were also higher in the diabetics, which may have constituted a protective response to other changes favouring the onset of vascular disease. Diabetics with retinopathy had higher factor VII and antithrombin III values, and those with proteinuria had higher values for factor VII, fibrinogen, and platelet adhesiveness than those without these complications. These findings suggest a potentially important association between a thrombogenic tendency and vascular disease in diabetes. Nevertheless, prospective data are needed to clarify whether the haemostatic abnormalities precede the onset of clinically manifest vascular complications or are a consequence of them.

Adult↗
PubMed1979

Nutrient intake, adiposity, and diabetes.

To study the role of nutritional factors in the genesis of diabetes, estimations of blood sugar concentration, food intake, and adiposity (as body mass index; BMI) were carried out on three normal population samples--namely, 961 employees of Beecham Ltd, 1005 employees of the Greater London Council, and 1488 middle-aged male civil servants (Whitehall study). Blood sugar concentrations and indices of glucose tolerance correlated positively with the degree of adiposity but tended to be negatively correlated with total food energy intake and its component nutrients (total carbohydrate, sucrose, and fat). This inverse trend was largely accounted for by highly significant inverse correlations between food energy intake and adiposity, a relation found in both sexes and in all three population samples and which extended across the whole range of nutrient intake and BMI. These findings suggest that greater degrees of adiposity are associated with lower than average food energy intakes and hence lower total energy expenditures. The association of increased adiposity with low food energy consumption may indicate an underlying "low energy throughput" state, and it may be the mechanisms of this, as well as the obesity, that are responsible for disease.

Adipose Tissue↗
PubMed1979

Worsening to diabetes in men with impaired glucose tolerance ("borderline diabetes").

Two hundred and four men with impaired glucose tolerance (borderline diabetes) discovered in a screening examination have been observed for five years and repeated tests of glucose tolerance performed. By pre-determined criteria 27 men 'worsened to diabetes' and this metabolic deterioration was not significantly influenced by treatment with carbohydrate restriction with or without a daily dose of 50 mg phenformin. Of the baseline variables measured prior to treatment allocation only the blood glucose values were significantly predictive of ultimate worsening to diabetes.

Blood Glucose↗
PubMed1979

Lipoproteins and plasma cholesterol esterification in normal and diabetic subjects.

Serum lipoproteins, separated by preparative ultracentrifugation and the activity of the plasma enzyme lecithin: cholesterol acyltransferase (LCAT) have been measured in insulin-dependent diabetics, non-insulin-dependent diabetics and in age-matched non-diabetic controls. In the insulin-dependent diabetics, mean total serum cholesterol and high density lipoprotein cholesterol (HDL-C) concentrations were significantly higher than in controls. Non-insulin-dependent diabetics had significantly raised total triglycerides and cholesterol, but HDL-C levels were essentially normal. The increased low density lipoprotein cholesterol (LDL-C) in both diabetic groups was statistically significant in men. A methodological study of HDL separation techniques was carried out to facilitate interpretation of these findings. Mean LCAT activity, by a method reflecting combined enzyme and substrate effects was significantly increased in these diabetic groups. The results confirm recent reports of a raised HDL-C in those insulin-dependent diabetics who are prone to coronary heart disease.

Cholesterol↗
PubMed1978

Glucose tolerance and blood pressure in two population samples: their relation to diabetes mellitus and hypertension.

The relationship between blood pressure and the blood sugar concentration measured two hours after a 50 g oral glucose load has been examined in two population surveys-the Whitehall and Bedford Surveys. In the Whitehall Survey, which was conducted in men above the age of 40, there was a positive, significant correlation between blood sugar and blood pressure (systolic and diastolic) which was independent of common associations with age, body mass index (BMI) and heart rate. In the Bedford Survey, systolic blood pressures were significantly higher in newly detected diabetics and borderline diabetics, both men and women, than in normoglycaemic controls after adjustment of blood pressures for age and BMI. However, in the stratified random sample of the cooperating Bedford population, only amongst women was the blood sugar significantly and independently correlated with the systolic blood pressure. Evidence is presented and discussed that autonomic, neurohumoral factors may play some part in the pathogenesis of maturity onset diabetes.

Adult↗
PubMed1977

Treatment of borderline diabetes: controlled trial using carbohydrate restriction and phenformin.

A five-year therapeutic trial of carbohydrate restriction with or without phenformin (50 mg/day) was performed in men with borderline diabetes. The aim of treatment was to diminish the enhanced risk of cardiovascular disease and deterioration of glucose tolerance. Cardiovascular morbidity and mortality were not significantly affected by any form of treatment, alone or in combination. The predominant risk factor for cardiovascular morbidity and mortality and for overall mortality was the initial blood pressure level. The baseline plasma cholesterol concentration significantly predicted the onset of intermittent claudication. One implication of the results is that hypotensive treatment, supplemented when necessary with hypolipidaemic treatment, may be more effective in preventing the progression of arterial disease in people with mild to moderate glucose intolerance than conventional antidiabetic therapy.

Blood Glucose↗
PubMed1976

Determination of antidromic excitation by the collision test: problems of interpretation.

Extracellular unit recordings were made from pontine reticular neurons in the cat and cells of the motor cortex in monkeys. In all cases, the characteristics of responses to electrical stimulation were studied using the tests of invariance of latency, high frequency following, and collision for determining the orthodromic or antidromic nature of the responses. The results of these tests show that their conclusions are not always consistent. A systematic error was found between the experimental and predicted values of the collision interval. It is argued that this error is due to differences in the application of measured parameters in calculating the collision interval. The collision test can be considerably improved by repeating the test with stimuli of progressively greater strengths.

Animals↗
PubMed1976

Brain stem reticular units: synaptic responses to stimulation within the ascending reticular pathways.

When the ascending reticular axonal system is stimulated, the responses of distal structures (e.g., the cerebral cortex) appear to outlast the stimulus; these longlasting effects could reflect the intrinsic nature of the distal structure, or the response could reflect an interaction among the reticular cells which tends to prolong the effects of stimulation. To examine the latter hypothesis, single units with ascending axons (projecting units) were recorded in the cat rostral rhombencephalon in acute experiments conducted under halothane-nitrous oxide anesthesia. Stimulation of areas to or through which axons of reticular neurons projected (midbrain tegmentum and lower tectum, medial thalamus, and basal forebrain) produced a consistent and specific response which was elicited only from these areas: suppression of spontaneous activity which was typically elicited from several areas having ascending axons. One-half of these responses were accompanied by a short latency-single spike synaptic excitation. Stimulating areas more than 1.0 mm from the ascending trajectory never produced this response, whereas the number of responses was directly related to the number of projecting axons identified in any one experiment from a given site. Thus, the predominant effect of stimulating within the ascending axonal trajectory was suppression of spontaneous activity in the projecting units, not an 'en cascade' activation of these units; on the contrary, the only type of excitation encountered was a single, short latency spike. Therefore, any effects of stimulation within the ascending reticular pathway which appear to outlast the stimulus (as previously described in the literature) cannot be ascribed to a reverberating (excitatory) circuit among projecting units. A possible source of the synaptic responses of projecting units is a retrograde activation of collaterals interconnecting the reticular cells. If such interaction exists, it is specifically distributed among cells with ascending axons, as the responses were only observed in a very few units not identified by antidromic excitation; however, other evidence is adduced to support the belief that these few units were projecting units whose axons were beyond the reach of the stimulating electrodes. Futhermore, the axons may be bundled such that units with axons nearest that of a given projecting unit give rise to the most extensive synaptic interactions; the activation of these nearby axons suppresses spontaneous activity, while axons farther away have a greater possibility of being excitatory in nature. Should such a medium for interaction exist, reticular collateral interactions might be seen to exist specifically for the purpose of decreasing the activity of cells destined for similar rostral target structures.

Animals↗
PubMed1975

Visual tracking and the primate flocculus.

Purkinje cells in the primate flocculus discharge specifically in relation to visual tracking, effectively generating a velocity profile of the target during pursuit. It is suggested that these neurons supply oculomotor centers with the velocity command signals needed to support pursuit eye movements.

Action Potentials↗