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Biomedical subjects

R D Ellis

Publications and source records attributed to R D Ellis.

At least 19 recordsLinked to original sources
PubMed1996

Predicting age-related differences in visual information processing using a two-stage queuing model.

Recent work on age-related differences in some types of visual information processing has qualitatively stated that younger adults are able to develop parallel processing capability, while older adults remain serial processors. A mathematical model based on queuing theory was used to quantitatively predict and parameterize age-related differences in the perceptual encoding and central decision-making aspects of a multiple-frame search task. Statistical results indicated main effects for frame duration, display load, age group, and session of practice. Comparison of the full model and a restricted model indicated an efficient contribution of the encoding speed parameter. The best-fitting parameter set indicated that (1) younger participants processed task information with a two-channel parallel system, while older participants were serial processors; and (2) perceptual encoding had a large impact on age-related differences in task performance. Results are discussed with implications for human factors design principles.

Adult↗
PubMed1996

Gero-informatics and the Internet: locating gerontology information on the World Wide Web (WWW).

The Internet, and in particular the World Wide Web (WWW), are growing at a tremendous rate. Information useful to researchers and practitioners in gerontology is scattered and hard to locate, even for experts in the use of the WWW. In order to locate and organize access to this material, a WWW server was developed for gerontologists, using state-of-the-art Internet search techniques. This report provides background on the WWW, reasons for its growth, its potential usefulness to gerontologists, and the results of an exhaustive search of over 300 potential sites. Relevant information was discovered in 5 general categories of gerontology-related information: academic institutions, government agencies, biomedical and health research institutions, general interest sites and data archives.

Aged↗
PubMed1996

Mesenteric vasculitis associated with Sézary syndrome.

A 71 year old lady with Sézary syndrome presented with chronic diarrhoea and cramping abdominal pains. A small bowel meal x ray examination showed two mid-ileal strictures. At laparotomy the small intestine was found to be sub-acutely obstructed and resection of a 15 cm ileal stricture and stricturoplasty of a second, 10 cm stricture were performed. Histological examination of the stricture revealed a mesenteric vasculitis with secondary ischaemic changes in the small bowel wall. Mesenteric vasculitis causing small bowel stricture may be associated with Sézary syndrome.

Aged↗
PubMed1993

False aneurysm complicating closed femoral fracture in a child.

False aneurysms are a recognized but rare complication of closed fractures. The authors report the case of a false aneurysm of the superficial femoral artery complicating a closed transverse fracture of the femoral shaft in a child treated with skeletal traction. The literature of this entity is reviewed.

Aneurysm, False↗
PubMed1991

Exaggerated and prolonged thyrotrophin releasing hormone (TRH) test responses in tertiary hypothyroidism.

A 60 year old man with panhypopituitarism due to a large meningioma and prolonged and exaggerated thyroid stimulating hormone (TSH) responses is described. Initial investigations showed a subnormal urinary free cortisol concentration, a low serum cortisol taken at 0900 hours, and a low free T4 concentration. The TSH was towards the upper end of the normal range. Subsequently pituitary function tests showed subnormal production of luteinising hormone in response to luteinising hormone releasing hormone (LHRH) and a short synacthen test with a low 30 minute cortisol value. Long synacthen testing showed a normal response at four days, confirming that the abnormalities were due to a pituitary or hypothalamic cause. A computed tomogram showed a large meningioma compressing the hypothalamus, pituitary, and temporal lobe. TRH testing showed a prolonged and exaggerated response, consistent with tertiary hypothyroidism.

Humans↗
PubMed1990

Monitoring ovarian cancer using urine cyclic GMP. A two-centre study.

The usefulness of urine cyclic guanosine 3'-5'monophosphate (GMP (cGMP) as a cancer marker in ovarian cancer has been studied in two independent centres using specimens from 81 women. Serial specimens from 60 patients were monitored up to 2 years after the start of chemotherapy. Urine cGMP levels were significantly higher in those patients with poorly differentiated tumours. Levels were not associated with the tumour stage, histological type or residual tumour remaining after surgery. Pretreatment levels were of no value for predicting response to therapy or patient survival. During therapy, however, levels did confirm clinical observations and if a level was elevated then there was a 80-90% chance that the patient was not responding to therapy. Using serial measurements, it was possible to predict the recurrence of tumour in 16/25 patients prior to any other clinical signs.

Biomarkers, Tumor↗
PubMed1989

Effects of BRL 35135, a beta-adrenoceptor agonist with novel selectivity, on glucose tolerance and insulin sensitivity in obese subjects.

BRL 35135 is a novel oral agent which, when dosed chronically to obese rodents with abnormal glucose tolerance, improves both insulin sensitivity and glucose tolerance. To study its effect in man, 10 obese patients on a weight-maintaining diet received BRL 35135 2 mg four times per day for 5 days and then 6 mg four times per day for 5 days. Oral 100 g glucose tolerance tests were performed 1 day prior to and 12 h after the 10-day treatment with BRL 35135. Simultaneously, energy expenditure, glucose oxidation and glucose storage were measured by open-circuit indirect calorimetry. No significant changes in body weight occurred during the 10-day treatment with BRL 35135. Areas under the curves for glucose and insulin were reduced following treatment with BRL 35135 (1518 +/- 152 to 1277 +/- 132 mmol/1/3 h, P less than 0.001 and 13.8 +/- 1.7 to 9.5 +/- 1.3 U/l/3 h, P less than 0.01) (mean +/- s.e.m.). In addition, plasma glucose concentrations, 2h post-oral glucose, were reduced significantly (8.7 +/- 1.0 mmol/l to 6.7 +/- 0.78, P less than 0.01). There was no effect of the treatment on glucose-induced thermogenesis and glucose oxidation did not change but glucose storage increased significantly. The results suggest that BRL 35135 improves glucose tolerance by an increase in insulin sensitivity that is independent of body weight. Glucose storage accounted for the increased glucose disposal.

Adult↗
PubMed1986

Differences between the effects of noradrenaline and the beta-adrenoceptor agonist BRL 28410 in brown adipose tissue and hind limb of the anaesthetized rat.

In mature (450-600 g) 21 degrees C-acclimated male rats, anaesthetized with urethane, blood flow (measured by the radioactive microsphere technique) to brown adipose tissue (BAT) was determined during the infusion of the beta-adrenoceptor agonist BRL 28410 or noradrenaline bitartrate at doses chosen to give similar increases in whole body oxygen uptake. Blood flow to BAT during BRL 28410 infusion was only about one third of that found during noradrenaline infusion although increases in whole body thermogenesis were similar (55 and 77% for BRL 28410 and noradrenaline, respectively). This suggests that BAT may be less involved in the thermogenic response to BRL 28410 than to noradrenaline. In a separate experiment using slightly smaller rats (350-500 g) hind limb oxygen uptake was measured in situ using a venous bypass preparation. BRL 28410, at a dose having a maximum effect on whole body thermogenesis (53% increase), had no effect on oxygen delivery to the hind limb but significantly increased oxygen extraction by 33% (p less than 0.001). In contrast, noradrenaline, also at a dose that maximally increased whole body thermogenesis, led to a 35% decrease in oxygen delivery to the hind limb and no change in oxygen extraction. For the thermogenic beta-agonist BRL 28410 the hind limb, and presumably muscular tissue in general, may be contributing to thermogenesis.

Adipose Tissue, Brown↗
PubMed1984

Treatment of obesity with thermogenic beta-adrenoceptor agonists: studies on BRL 26830A in rodents.

Studies on BRL 26830A in rodents have shown that thermogenic beta-adrenoceptor agonists have potential for the therapy of obesity. BRL 26830A reduced body weight gain in ob/ob mice and fa/fa rats by reducing lipid accumulation. It had no effect on lean body mass. BRL 26830A did not reduce food intake, its anti-obesity effect being due to stimulation of energy expenditure. This thermic effect was enhanced in the obese animals by repeat dosing. BRL 26830A did not affect body weight gain in the lean counterparts of the obese animals because its thermic effect in lean animals was reduced by repeat dosing. Brown adipose tissue is an important site of BRL 26830A-induced thermogenesis. A single dose of BRL 26830A raised brown adipose tissue temperature, depleted brown adipose tissue lipid and unmasked GDP-binding sites in brown adipose tissue mitochondria. Repeat dosing caused hypertrophy of brown adipose tissue and improved cold tolerance in mice. In-vitro studies showed that the rat brown adipocyte beta-adrenoceptor does not fall into the beta 1/beta 2 classification and BRL 28410, which mediates the biological effects of BRL 26830A in vivo, selectively stimulated the brown adipocyte receptor. It is concluded that BRL 26830A achieves its anti-obesity effect by mimicking natural mechanisms involved in thermogenesis and the control of body weight.

Adipose Tissue, Brown↗
PubMed1982

Cyclic GMP in urine to monitor the response to ovarian cancer to therapy.

Guanosine 3':5'-phosphate (cycle GMP) in urine has been used to monitor the response of patients with ovarian cancer to treatment. Changes in the cyclic GMP level appear to correlate well with clinical status in that the disappearance of clinically detectable tumour is associated with a drop in the level whereas a tumour recurrence is associated with an elevation. Serially measured cyclic GMP is valuable for detecting a recurrence of tumour growth in patients in clinical remission and can predate any clinical signs by as much as 10 months. In patients who show no response to treatment, cyclic GMP levels in urine are elevated in the majority of specimens collected.

Creatinine↗
PubMed1982

Urine cyclic nucleotide concentrations in cancer and other conditions; cyclic GMP: a potential marker for cancer treatment.

Cyclic guanosine 3',5' monophosphate (cyclic GMP) and cyclic adenosine 3',5' monophosphate (cyclic AMP) have been determined in random urine specimens from 95 healthy individuals, 60 patients with non-cancerous conditions, 52 patients with benign tumours, and 74 patients with malignant tumours. Concentrations of cyclic GMP have also been determined in a number of other groups, including some undergoing cancer treatment. Ninety-three per cent of cancer patients had raised urinary cyclic GMP concentrations compared to the reference range for healthy subjects. For the non-cancerous and benign groups, 33% and 42% respectively had raised concentrations. The urine cyclic AMP concentrations were similar in all groups. Urine cyclic GMP appeared to rise early in the onset of malignant growth. Successful cancer treatment was accompanied by a dramatic fall in the urine cyclic GMP concentrations, whereas if the treatment was unsuccessful the level did not change. It is concluded that urine cyclic GMP may have important applications in the monitoring of cancer treatment.

Adolescent↗