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R Withers

Publications and source records attributed to R Withers.

16 recordsLinked to original sources
PubMed1999

Feasibility of external beam radiation for prevention of restenosis following balloon angioplasty.

PURPOSE: Brachytherapy has been shown to inhibit neointima formation after vascular balloon injury. This study was done to test the feasibility of low dose external radiation for prevention of restenosis in a non-stented balloon injury model. MATERIALS AND METHODS: Twelve red Duroc swine underwent balloon overdilation injury of both iliac arteries. Twelve Gy was delivered to one side using a Theratron T-1000 Cobalt unit with the other side used as the control. Twelve weeks post injury arteriograms were performed. The animals were then sacrificed and iliac arteries explanted. Histomorphometric analysis of arterial cross sections was performed. RESULTS: Neointima formation was observed in all arteries. Unilateral thrombosis was noted in two animals. The mean neointimal thickness in the radiated and control arteries was 0.63 +/- 0.17 mm and 0.72 +/- 0.31 mm, respectively. The differences in minimal luminal diameter and the neointimal thickness between the two groups were not statistically significant. Complications included superficial hair loss in the radiation port in 4 animals, and 2 deaths prior to the completion date (1 of hemorrhagic enteritis possibly related to the radiation, and 1 of iliac rupture). CONCLUSION: External radiation at this low dose is not effective in preventing vascular restenosis following balloon injury in this animal model.

Angioplasty, Balloon↗
PubMed1998

In search of a dose-response relationship with radiotherapy in the management of recurrent rectal carcinoma in the pelvis: a systematic review.

PURPOSE: A systematic review of the literature was undertaken to address the question: "What is the most effective dose fractionation schedule for the relief of symptoms in patients with pelvic recurrence from rectal or colorectal carcinoma?" METHODS AND MATERIALS: Cancerlit/Medline-computerized databases were searched between the years 1966-1996. Studies that explored the response to radiotherapy in patients with pelvic recurrence from rectal/rectosigmoid carcinoma were included. Factors that may contribute to differences in results were postulated in advance and the variations encountered between articles were presented. Articles with data applicable to recurrent disease only were included in the primary analysis. The effect of including articles that reported outcomes of recurrences with unresectable primaries and residual disease was presented as a sensitivity analysis. RESULTS: Only retrospective series (level V evidence) were available. The many sources of potential bias inherent in retrospective analyses make the data suitable for hypothesis generation only. Comparison of response was made between "lower" vs. "higher" doses, using 45-50 Gy as the dividing dose, base on the primary analysis. There were no significant differences observable in terms of initial response and the proportion maintaining a response at 6 months, within the range of doses employed. When data from articles that reported outcomes of recurrent disease with primary untreated cancers and postoperative residual disease were included, there was a suggestion for a more favorable response with higher doses. This requires cautious interpretation within the methodological limitations of the data. CONCLUSION: The optimal dose fractionation schedule for the palliation of pelvic recurrence from rectal carcinoma remains undefined. Well-designed randomized studies, with study arms that are sufficiently diverse biologically to allow the detection of a dose-response relationship if one existed, equipped with suitable symptom control end points, are necessary to provide a clinically relevant answer.

Dose-Response Relationship, Radiation↗
PubMed1986

Verapamil and breast-feeding.

Concentrations of verapamil and norverapamil were measured in the plasma and breast milk of a woman receiving 120 mg verapamil three times daily. Whilst the concentrations of verapamil in breast milk averaged about 64% of those in maternal plasma no drug could be detected in the plasma of the infant. It is concluded that maternal therapy with verapamil does not pose a hazard to the suckling infant.

Adult↗
PubMed1983

Evidence of congenital heart disease in the offspring of parents with atrioventricular defects.

Fifty-two of the 56 offspring from 90 patients with proven atrioventricular defects were examined. There were five with congenital heart disease. The defects were concordant in three and discordant in two. The mother was the affected propositus in all cases. In this relatively small sample the incidence of congenital heart disease in the offspring of parents with atrioventricular defects was 9.6%, or 14.3% if only the female propositi were considered. This is a much higher figure than that reported for the simple forms of isolated congenital heart disease.

Adult↗
PubMed1978

Congenitally bicuspid aortic valves. Clinicogenetic study of 41 families.

The families of 41 patients with surgically proved isolated bicuspid aortic valves were examined. There were 275 first degree relatives of whom 220 were living, and 188 (85.5%) of these were examined. Seven first degree relatives were found to have aortic valve disease, and in a further 11 there was 'doubtful' evidence of bicuspid aortic valves. In 6 families there was more than 1 affected member and in an additional 7 families there was 1 or more 'doubtful' first degree relative. The minimum family incidence was therefore 14.6 per cent, or 31.7 per cent if 'doubtful' cases were included. The inheritance is most probably multifactorial, but occasionally the condition may occur as an autosomal dominant. The difficulties of diagnosing bicuspid aortic valves before the development of obstruction of left ventricular outflow were encountered and are discussed. The association of a bicuspid aortic valve with asymmetric septal hypertrophy, hypertrophic cardiomyopathy, and Marfan's syndrome was also noted.

Aortic Valve↗
PubMed1977

Formes frustes of Marfan's syndrome presenting with severe aortic regurgitation. Clinicogenetic study of 18 families.

Eighteen patients who presented with severe aortic regurgitation and dilatation of the ascending aorta were found to be formes frustes of Marfan's syndrome and formed the basis for this clinicogenetic study. All had aortic valve replacement and reconstruction of part of the ascending aorta. The diagnosis was confirmed by histological examination of the aortic tissue. There were 126 first degree relatives; 85 were living and 67 (78-8%) of these were examined. Limited information was available about 32 of the 41 relatives who had died. No relative had the classical clinical features of Marfan's syndrome but stigmata of the disease were found in 25 (37-3%) of the 67 first degree relatives examined. In 21, the abnormality was confined to the cardiovascular system, the skeleton, or the eye, but in 4, abnormalities involved 2 systems. Cardiovascular abnormalities affecting the aortic valve or aortic wall were present in 6 (9-0%) of the 67 first degree relatives examined. One or more of the skeletal indices measured (height-span difference, metacarpal index, phalangeal index) was abnormal in 18 (26-9%) and ocular abnormalities were found in 5 of 51 (9-8%) examined. There were no relatives with dislocation of the lens or iridodonesis. Using strict diagnostic criteria, a minimum of 37-3 per cent of the first degree relatives examined were affected; this involved 12 of the 18 families studied. There was nothing in our data to suggest that the formes frustes of the disease had a different mode of inheritance from the classical syndrome.

Adult↗
PubMedDate not supplied

The relation of age to the thickness of the interventricular septum, the posterior left ventricular wall and their ratio.

We obtained echocardiographic measurements of interventricular septal and posterior left ventricular wall thickness in 100 apparently normal subjects in whom there was no evidence or history of coronary artery disease, hypertension or prolapsing mitral valve. Subjects were divided into five age groups of 20-29, 30-39, 40-49, 50-59 and 60-70 years and there were 20 subjects in each group. Measurements of interventricular septum and posterior left ventricular wall thickness were made in each subject at both mitral and sub-mitral levels at the time of Q wave inscription, and the measurements were related to body surface area. The interventricular septum increased from a median of 8.3 mm in the age group 20-29 to 11.2 mm in the group 60-70, whereas the posterior left ventricular wall increased from 7.5 mm to 9.8 mm. The difference in the medians between the groups 20-29 and 60-70 was statistically significant for both interventricular septum and posterior left ventricular wall (P less than 0.02). Our data showed that interventricular septal, posterior left ventricular wall thickness measurements and their ratio should be related to age in order to assess their significance.

Adult↗
PubMedDate not supplied

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Attitude of Health Personnel↗