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Biomedical subjects

G Williams

Publications and source records attributed to G Williams.

At least 343 records · Page 19Linked to original sources
PubMed1994

Assessment of blood flow changes at multiple sites in rabbit skin using a 133Xenon clearance technique.

133Xenon clearance represents a clinically useful method of measuring local circulatory function in a variety of different tissues. The method detailed in this article describes how the 133Xenon clearance technique can be adapted to simultaneously measure cutaneous blood flow, over a 15-min period, at a large number of skin sites within the same animal. Blood flow changes are measured in response to intradermally injected vasoactive test agents. The multisite injection plan which forms part of the method removes bias due to site variations and generates data that can be analysed statistically. Results are expressed as the percent change in 133Xenon clearance at test agent-injected sites as compared to control, saline-injected sites. The method provides an accurate and time-efficient measure of skin blood flow. In the present study, the technique is used to assess the receptor-mediated mechanism of action of the vasodilator calcitonin gene-related peptide (CGRP) and the possibility that the vasoconstrictor endothelin-1 acts to stimulate the release of vasodilator quantities of endogenous CGRP.

Animals↗
PubMed1994

Endometrial ossification: a cause of secondary infertility. Report of two cases.

Two cases of endometrial ossification with secondary infertility are reported; pelvic ultrasonography suggested an intrauterine foreign body in one case. Hysteroscopy was necessary to make the correct diagnosis and to remove the bony fragments from the two cases. One patient conceived naturally after the bony fragments were removed.

Abortion, Induced↗
PubMed1994

A modified prostatic UroLume Wallstent for healthy patients with symptomatic benign prostatic hyperplasia: a European Multicenter Study.

OBJECTIVES: This European multicenter study was aimed to assess the clinical reliability of a modified prostatic UroLume Wallstent (American Medical System, Minnetonka, MN) in the treatment of 135 healthy patients with symptomatic benign prostatic hyperplasia. METHODS: Ninety-one patients who were obstructed but still voiding spontaneously and 44 patients who had an indwelling catheter were treated by placement of a modified stent. RESULTS: A significant improvement in mean peak flow rates and residual urine volumes was maintained throughout follow-up. Both obstructive and irritative voiding symptoms were significantly improved after placement of the stent, although a greater amelioration was seen in obstructive symptoms. The rate of patients reporting erections increased after stent insertion. Eighty percent of sexually active patients reported the maintenance of antegrade ejaculation postoperatively. A greater than 80% epithelialization of the stent was seen in 28 patients (100%) examined at the 18-month follow-up. Long-term complications were seen in 51 patients (38%). Twenty-one of these patients had the stent removed due to intractable detrusor instability, stent encrustation, stent migration, or persistence of obstruction due to prominent median lobe, understenting, or severe hyperplasia of the epithelium of the prostatic urethra. In 6 of them another stent was reimplanted while the others were treated surgically. CONCLUSIONS: Although this modified stent was abandoned due to an unacceptable rate of complications, this study demonstrates that bladder outlet obstruction in healthy patients with benign prostatic hyperplasia can be successfully relieved by the placement of a UroLume Wallstent.

Aged↗
PubMed1994

Risk factors in the development of ocular surface epithelial dysplasia.

BACKGROUND: Ocular surface epithelial dysplasia involves a spectrum of diseases ranging from only minor eye irritation to blindness and potentially death. METHODS: A case-control study involving 60 patients with ocular surface epithelial dysplasia treated between 1972 and 1991 and 60 age- and sex-matched individuals was conducted to compare relative ultraviolet light exposures over their lifetimes. A standardized self-administered ultraviolet exposure questionnaire was used for assessment. RESULTS: Risk factors identified include phenotypic features such as fair skin (odds ratio [OR], 5.4; 95% confidence interval [CI], 1.1, 25.6), pale iris (OR, 1.8; 95%; CI, 0.9, 3.8), and propensity to sunburn (OR, 3.8; 95% CI, 0.7, 19.7), history of previous skin cancers removed (OR, 15; 95% CI, 2.0, 113.6), and being outdoors more than 50% of time in the first 6 years of life while living 30 degrees or less from the equator (OR, 7.5; 95% CI, 1.8, 30.6). CONCLUSION: These risk factors suggest that ocular surface epithelial dysplasia is an ultraviolet light-related disease.

Adult↗
PubMed1994

The benefits of low-dose aspirin therapy in women with impaired uterine perfusion during assisted conception.

The objective of this long-running study was to determine whether the addition of low-dose aspirin to a standard hormone replacement therapy (HRT) protocol improved uterine perfusion during assisted conception. A total of 99 women scheduled for frozen embryo replacement were studied. Endometrial preparation was with a standard buserelin/HRT protocol. Uterine perfusion was assessed by Doppler ultrasound and classified as impaired or normal. In their first attempts, those with impaired perfusion (group I, n = 37) received low doses of aspirin [150 mg (n = 26) or 300 mg daily (n = 11)], starting from day 13 of HRT. Women with normal perfusion (group II) did not receive aspirin. In subsequent attempts, those from group I were arbitrarily allocated to start aspirin on day 1 or day 13 of HRT, and 10 women from group II were arbitrarily selected to receive aspirin from day 1 of HRT. In group I, the cancellation (46 versus 36%) and pregnancy rates (15 versus 25%) in those who received 150 or 300 mg aspirin daily were similar. In those with cancelled first attempts, good perfusion was achieved in 82 versus 20% (P < 0.02) of subsequent attempts using aspirin from day 1 versus day 13 of HRT. Higher pregnancy rates (47 versus 17%) were achieved in those taking aspirin from day 1 of HRT. In group II, pregnancy rates were not statistically different in those who did or did not receive aspirin during their subsequent attempts (10 versus 35%). The addition of low-dose aspirin to a standard HRT protocol in women with impaired uterine perfusion is associated with improved blood flow and satisfactory pregnancy rates.

Aspirin↗
PubMed1994

Neutrophil activation and morbidity in young adults with cyanotic congenital heart disease.

Young adults with cyanotic congenital heart disease have a high incidence of respiratory and haemostatic problems. Activated neutrophils release vasoactive and chemotactic factors which result in endothelial injury, lung parenchymal damage and the activation of platelets and coagulation pathways. To investigate the contribution of neutrophil activation to morbidity in young adults with cyanotic congenital heart disease, plasma neutrophil elastase levels were measured in 25 cyanotic patients and the results compared to patients with acyanotic heart disease and normal controls. Neutrophil elastase levels were significantly elevated in the group with cyanotic congenital heart disease (P < 0.001). Platelet activation was significantly increased in the patients with cyanotic heart disease (P < 0.001). Platelet aggregation was impaired only in those with haematocrits greater than 0.50 (P < 0.02). Whole blood coagulation, as determined by thrombelastography, was within normal limits. The reason for neutrophil activation in patients with cyanotic congenital heart disease is unclear, but activated neutrophils may contribute to the respiratory and haemostatic problems common to these patients.

Adult↗
PubMed1994

Acute dexfenfluramine administration normalizes glucose tolerance in rats with insulin-deficient diabetes.

Dexfenfluramine has been shown to lower blood glucose concentrations independently of its effects in reducing food intake and body weight, in human and animal syndromes of non-insulin dependent diabetes. This study aimed to determine whether dexfenfluramine could also reduce glycaemia in rats with severe insulin-deficient diabetes induced by the beta-cell toxin, streptozotocin (55 mg kg-1). Three weeks after diabetes induction, nine groups (each n = 10) of diabetic and non-diabetic rats underwent oral glucose tolerance tests (1 g kg-1, by gavage). These tests were preceded by 12-18 h of fasting to remove the confounding effects of hyperphagia in diabetic rats, and to stabilize glycaemia. Dexfenfluramine (1.0 mg kg-1), given 2 h before the glucose challenge, significantly reduced basal glycaemia and decreased the post-challenge glycaemic rise (P < 0.01 vs. untreated diabetics). Dexfenfluramine dosages of 2.5 and 5.0 mg kg-1 both further flattened the post-challenge glycaemic profiles (both P < 0.01 vs. untreated diabetics) and achieved levels that did not differ significantly from those in non-diabetics (both P > 0.05). Subsequently, the studies using dexfenfluramine dosages of 2.5 and 5.0 mg kg-1 were repeated to determine whether the drug affected plasma insulin levels 2 h after dosing. In diabetic rats, plasma insulin concentrations were reduced to 10-20% of non-diabetic values, and were not significantly altered by dexfenfluramine. Acute dexfenfluramine administration therefore improves and (at dosages of 2.5 and 5.0 mg kg-1) essentially normalizes glucose tolerance in rats with severe insulin-deficient diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Neuropeptide Y and energy balance: one way ahead for the treatment of obesity?

Obesity is a vast and ever-expanding problem in affluent societies, which we have so far failed to confront. Over 20% of Western European and North American adults are overweight to a degree which may potentially shorten their life expectancy. Obesity has well-known associations with non-insulin-dependent diabetes (NIDDM), hypertension, dyslipidaemia and coronary heart disease, as well as less obvious links with diseases such as osteoarthrosis and various malignancies; it also causes considerable problems through reduced mobility and decreased quality of life. The overall financial burden of obesity is impossible to calculate precisely, but may account for 6-8% of total health-care expenditure in North America [1] (similar estimates probably apply to Western Europe). Obesity is difficult to treat and many patients remain obstinately overweight despite our best efforts. The available options range from behavioural therapy to gastrointestinal surgery and include numerous drugs designed to suppress appetite or increase energy expenditure. As in many other areas of medicine, the length and diversity of this list are reliable signs that effective treatment is still beyond our reach. This article argues that new anti-obesity drugs may emerge from recent advances in understanding the control of energy balance in rodents. The discussion is structured around neuropeptide Y (NPY), a major brain peptide which at present appears to be important in regulating energy balance and seems a promising candidate for therapeutic exploitation.

Animals↗
PubMed1994

Smoking attenuates the vasoconstrictor response to noradrenaline in type I diabetic patients and normal subjects: possible relevance to diabetic nephropathy.

Exaggerated vascular reactivity has been implicated in the pathogenesis of diabetic nephropathy, and several studies suggest that smoking accelerates its progression. We therefore assessed the vasoactive effects of smoking by comparing noradrenaline-induced vasoconstriction in dorsal hand-veins between smoking and non-smoking groups of Type I diabetic patients with and without microalbuminuria and in non-diabetic subjects. Smokers had a significantly higher dose causing 50% vasoconstriction (reduced sensitivity to noradrenaline) in all three groups: microalbuminuric diabetic smokers vs. nonsmokers, 20.2(4.6) (SEM) vs. 6.6(2.3) ng min-1 (P = 0.02); normoalbuminuric, 76.9(29.4) vs. 22.8(9.1) ng min-1 (P = 0.03); non-diabetic subjects, 97.8(30.0) vs. 38.0(12.8) ng min-1 (P = 0.01). Both microalbuminuric diabetic groups showed significantly greater sensitivity to noradrenaline-induced vasoconstriction than the other smoking and non-smoking groups, respectively (P < 0.01). Vasoconstrictors responses to noradrenaline are attenuated in smokers, possibly due to alpha-adrenoceptor down-regulation. Smoking could increase urinary albumin losses and accelerate renal damage through catecholamine surges which raise systemic and, perhaps, intraglomerular blood pressure. This hypothesis deserves further consideration.

Adult↗
PubMed1994

Influence of motivational and demographic factors on performance in the medical course: a prospective study.

A questionnaire was completed by students entering the University of Queensland (Australia) MB BS course in 1983 and 1984 (n = 399). It contained wide-ranging questions regarding the decision to enter medicine, including how, why and when the decision was reached. Demographic data were also collected. All but two students have now completed their involvement with the course. The most important determinant of qualifying MB BS was geographical, metropolitan students doing so in greatest proportion. High levels of course performance were predicted by father's occupation, and being aware of a widely held attitude, namely that it would be a pity not to enter medicine if able to do so. Several gender differences are noted. Finally, it was noteworthy that the predictive aspects of questionnaire responses did not lessen as students progressed through the course.

Career Choice↗
PubMed1994

Preliminary report--combined surgical and radiological penile vein occlusion for the management of impotence caused by venous-sinusoidal incompetence.

OBJECTIVES: To combine surgical and radiological penile vein occlusion therapy in the treatment of patients with venogenic impotence, to try to improve on the results of either treatment used separately. PATIENTS AND METHODS: Fourteen patients, with a mean age of 46 years (range 25-71), with pure venous-sinusoidal impotence were treated by surgical ligation of accessible veins and embolization of surgically inaccessible veins. The preliminary results over a follow-up period of at least 8 months are reported for each patient. RESULTS: Venous embolization was considered complete in 11 patients. Overall, 13 had improved erectile function. Post-operatively, eight patients developed spontaneous erections and four (aged < 40 years) have maintained this for 8-24 months. CONCLUSION: Combined surgery and radiology treats the end result of the failure of the sinusoidal smooth muscle to relax. Although some patients, the majority of whom are young (aged < 40 years), will achieve short-term benefit, all individuals need to be fully counselled with regard to the likelihood of long-term benefit before undergoing this invasive method of treatment.

Adult↗
PubMed1994

The nutcracker syndrome: an uncommon cause of haematuria.

OBJECTIVE: To increase the awareness of this rare cause of haematuria and to describe the operative techniques available for its treatment. PATIENTS AND METHODS: The investigation and treatment of five patients with the nutcracker syndrome have been reviewed. RESULTS: A new variant of the nutcracker syndrome is described. Using a combination of venolysis, Gortex graft renal vein interposition and an anterior nephropexy, the haematuria of four patients has ceased and improved in one. CONCLUSION: The nutcracker syndrome is a rare cause of haematuria which responds successfully to surgical treatment. Successful treatment does not appear to be related to lowering of the renal vein pressure.

Adult↗
PubMed1994

Passive smoking and impaired lung function in cystic fibrosis.

Passive smoking was measured in 57 children with cystic fibrosis and in 51 controls using a questionnaire and a measurement of urinary cotinine concentration. In the cystic fibrosis group, cotinine was significantly lower than in the controls. Also in this group, when the parents smoked the child's forced expiratory volume in one second decreased by 4% and the forced vital capacity by 3% for every 10 cigarettes smoked in the household each day.

Adolescent↗