Biomedical subjects
Publications and source records attributed to D Wilson.
An oesophageal tube provided with a foam-rubber cuff is described. The outside diameter of the cuff can be diminished while the tube is being introduced. After implantation, the expanded foam-rubber cuff achieves additional sealing of the oesophago-bronchial fistula. The tube described is suitable for sealing off oesophago-bronchial fistulae in the absence of the tumour-induced stenosis of the oesophagus.
To determine if collateral ventilation (CV) occurs in pigs and dogs during intermittent positive-pressure ventilation (IPPV) and high-frequency oscillation (HFO), seven pigs and seven dogs were studied by measuring Xenon 133 washout (XeW) from an occluded subsegmental bronchus. The rate constant/min (K) for Xe blood uptake (KXeb) was derived, and when subtracted from K for XeW (KXeW) gave K for removal of Xe by CV (KXecv). Pig XeW were single exponentials with mean KXew = 0.25/min during IPPV and 0.12/min with HFO. In pigs, mean K of XeW was no different from KXeb so that all XeW occurred by blood uptake and none by CV. XeW in dogs had two exponentials. Dogs had over 11 times greater mean KXeW than pigs during IPPV and over 24 times greater during HFO. In dogs, on average, 79% (IPPV) and 87% (HFO) of XeW occurred by CV. CV is a means of gas exchange during HFO and IPPV in dogs but not in pigs.
Perindopril is a new inhibitor of converting enzyme activity with a prolonged half-life. Thirty-two patients with essential hypertension and a diastolic blood pressure greater than 95 mm Hg were stratified into two groups according to their 24 h urine sodium excretion. They were randomized in a double-blind fashion to placebo or perindopril and a dose titration made in steps of 2, 4, 6, and 8 mg given once daily at weekly intervals. The goal diastolic blood pressure was 90 mm Hg. Goal blood pressure was achieved in 11 of 16 patients on perindopril and 3 of 6 patients on placebo. Perindopril caused a fall in BP of 22/11 (supine) and 27/14 (erect) mm Hg while the placebo group had falls of 3/2 (supine) and 3/0 (erect) mm Hg. Most of the blood pressure fall occurred in the first week of therapy with 2 mg/day. Side effects were few and occurred mainly in the placebo phase. There was no alteration in urine protein, white cell count, plasma urea, or creatinine. The fall in blood pressure achieved at the end of the titration or with 2 mg did not differ between the two groups. There was no correlation between blood pressure response and 24 h urine sodium or plasma renin activity. These results indicate that perindopril is an effective antihypertensive drug that appears to work equally well in patients on high or low sodium intake.
Prenatal diagnosis in a pregnancy at risk for Becker muscular dystrophy is reported. The diagnosis was made prior to 12 weeks of gestation by typing a CVS sample for DNA markers.
Clear cells showing characteristic features of koilocytotic atypia were found in 41 (82%) of 50 paraffin sections of urinary bladder tumour. Papillomavirus common structural antigen was detected in seven (14%) of the samples using an avidin-biotin peroxidase staining technique. The results suggest a role for the human papillomavirus in the aetiology of urinary bladder neoplasia.
Repeated, daily, open sodium lauryl sulfate (SLS) applications caused slight alterations in transepidermal water loss (TEWL) and dielectric water content (DEWC) in males and females. No erythema developed. Inter-individual variation in skin reactivity was demonstrated; sex-related patterns in reactivity to open cumulative irritant exposure did not exist. In patch testing with 0.5 and 1% SLS, reflecting acute irritation capacity, the reaction pattern, assessed by TEWL, DEWC, laser Doppler velocimetry (LDV) and visual scoring (VS), differed from that induced by open, cumulative SLS irritation. Again, inter-individual variation in the reactivity was demonstrated; significant sex-related differences did not develop. Individual reactivity showed considerable variation in acute and cumulative irritant response and was greater than the sex-related variation. We did not identify responses demonstrating that women have delicate (easily irritated) skin, nor that males have "tougher" skin than females.
The variation in human skin response to sodium lauryl sulfate (SLS) was determined with patch and open applications. Reactions in different subjects and in multiple simultaneous patch tests were compared. Skin responses were assessed with visual scoring (VS), laser Doppler velocimetry (LDV) and transepidermal water loss (TEWL). Previous open, unpatched SLS exposure decreased patch test reactivity to 1% SLS assessed with VS (p less than 0.05) or LDV (p less than 0.05). Corresponding TEWL alteration was inconstant. Variation in reactivity at different test sites in multiple simultaneous tests was considerable, though less than the variation at different test times (p less than 0.05). Inter-subject variation in test reactivity was greater than the variation between different test times or adjacent test sites. Repeated open applications and the subclinical dermatitis appear to have produced a hyporeactive state. The results suggest that non-specific skin inflammation is elicited by multiple factors, e.g., stratum corneum integrity and vascular reactivity. Their balance determines the ensuing reactions. The induced hyporeactivity may be one of many causes of false negative diagnostic patch tests.
Successful eradication of Pseudomonas peritonitis is described in 12 (57%) of 21 cases from a large continuous ambulatory peritoneal dialysis (CAPD) program at a tertiary care center. In successful cases, cure was achieved within 17 days using therapy which included aminoglycoside started routinely at the onset of symptoms and an antipseudomonal penicillin or cephalosporin derivative added as soon as pseudomonas infection was identified on culture. Of the 9 treatment failures which required catheter removal, 2 had failure of peritoneal drainage, 4 had infection with multiple and/or drug-resistant Pseudomonas strains, and 3 had persistent catheter tunnel infection which resulted in recurrent Pseudomonas peritonitis. Factors such as diabetes mellitus and pediatric age group did not prevent successful medical therapy. Predisposing factors favoring development of Pseudomonas peritonitis included technical failures and in a few cases recent antibiotic therapy. We conclude that Pseudomonas peritonitis complicating CAPD can be successfully cured without catheter removal or discontinuation of CAPD in many cases, particularly when complicating factors are not present.
Breakdown in the blood-retinal barrier occurs in retinal neovascularization in a number of diseases. To study the anatomic basis of this breakdown, we examined retinal neovascularization induced by injection of 250,000 homologous fibroblasts into the vitreous cavity of pigmented rabbits. Neovascularization is evident by electron microscopy in this model 3 days after fibroblast injection. Fluorescein angiography followed by intravenous horseradish peroxidase (HRP) injection was performed prior to enucleation on 2, 3, 5, 7, and 14 days after fibroblast injection. Fluorescein leakage from retinal vessels occurs early (at day 1) and persists as the neovascularization progresses. The leakage in the early stages is concentrated near puckers from the medullary wings. In the later stages, fluorescein leakage is most prominent in the developing tips of the new vessels. Horseradish peroxidase was not observed to leak from the lumen of new vessels. "Gaps" or separations in the endothelial cell junctions were not observed in developing vessels. The breakdown of the blood-retinal barrier in this model of retinal neovascularization is therefore selective, (ie, fluorescein leaks but not HRP) and it is not due to gaps or fenestrations between endothelial cells in developing vessels.
At least three marked differences were noted in the results compared from two parallel experiments using identical protocols with virus-free mice and mouse hepatitis virus (MHV) infected mice inoculated with P388 leukemia. First, the therapeutic effect of cyclophosphamide (CY), a cytotoxic antitumor drug, was apparently augmented in MHV-infected mice. A 162% increase of life span (ILS) was obtained in MHV-infected mice compared to a 100% ILS in uninfected mice. Second, the experimental error in terms of the range of animal survival time was much larger with MHV-infected mice than with uninfected mice. In MHV-infected mice, the therapeutic effect of the combination treatment with CY and pyrimidinone was not statistically different from that of the treatment with CY alone. In uninfected mice, the effects of the combination therapy at all doses of pyrimidinone were statistically more effective than that of CY treatment alone.
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A series of stable complexes of 153Sm has been produced using multidentate acetate and phosphonate ligands. Biodistribution studies in unanesthetized rats showed varying degrees of bone and soft-tissue uptake for these complexes. Of the complexes studied, [153Sm] ethylenediaminetetramethylenephosphonate (EDTMP) showed the best combination of high bone uptake, low nonosseous uptake, and rapid blood clearance which warranted its further investigation in rabbits. Rabbit studies confirmed the [153Sm]EDTMP results obtained in rats. Blood clearance in rabbits was found to be more rapid than [99mTc] methylene diphosphonate (MDP). Scintigraphic images were virtually indistinguishable from [99mTc]MDP images. Lesion/normal bone ratios were determined from digitized images obtained using a drill hole model and found to be approximately 17:1. Based on these excellent biodistribution characteristics, [153Sm] EDTMP could be therapeutically useful in treating metastatic bone cancer.
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A notes survey was undertaken by a group of eight general practitioners in seven Southampton practices to study the mode of presentation and follow-up of the diabetic patients on the lists of 24 doctors. The 431 known diabetic patients were classified as non-insulin-dependent (67%), insulin-dependent (20%), or, if they had commenced their insulin more than a month after the diagnosis had been made, 'insulin-treated' (13%). This classification allowed characterization of the truly insulin-dependent and non-insulin-dependent patients.Non-insulin-dependent diabetics were older than insulin-dependent diabetics and had first presented at a greater age. Most patients in each treatment group presented with classical diabetic symptoms, diabetes-related infections, or recognized complications. The majority of these were diagnosed in general practice. However, over half of the asymptomatic non-insulin-dependent diabetic patients had been diagnosed by routine blood or urine testing in hospital. After 1979 fewer non-insulin-dependent diabetic patients were referred to hospital for follow-up at diagnosis than before 1975.Most non-insulin-treated diabetics were followed up in general practice whereas most patients treated with or dependent on insulin were followed up in hospital clinics. Twenty-two per cent of all patients received diabetic care from both their general practitioner and hospital outpatient departments but 20% received no regular diabetic follow-up at all. One year after the initial study, 4% of patients were still without regular review, and 27 more patients had been identified who would have qualified for the original audit.
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An important part of public health policy on the control of smoking is the promotion of a reduction in intake of tar by persons who continue to smoke. One method that may contribute towards such a reduction is to encourage smokers to choose cigarette brands that contain low tar levels. This in turn might be promoted by the comprehensible labelling of cigarette packets with tar yields. We tested our hypothesis that the current information about tar yield on cigarette packets is incomprehensible to smokers on a sample of 498 persons (original sample, 500) who smoked. Only 10 (2%) smokers were able to state the correct tar content of their cigarette. On a scaled range of tar levels in all cigarette brands that are available in Australia, 344 (69.1%) smokers underestimated the level in their cigarette brand. On this scale, 280 (56%) smokers placed randomly chosen tar levels in the wrong category. It was agreed by 360 (72%) smokers that comparative tar yields should be displayed at all points of tobacco sale. It is recommended that a condition of issuing a licence to retail tobacco should be that the tar, nicotine and carbon monoxide yield information for all cigarette brands that are available in a national market should be displayed prominently to the consumer by the retailer.
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