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Biomedical subjects

D Arlen

Publications and source records attributed to D Arlen.

8 recordsLinked to original sources
PubMed2005

Management of asymptomatic cholelithiasis for patients awaiting renal transplantation.

BACKGROUND: There is no consensus regarding the most appropriate management of asymptomatic cholelithiasis in patients awaiting renal transplantation. Cholecystectomy is considered before renal transplantation because of potential worsened complications from cholelithiasis with posttransplantation immunosuppression. This study reviewed the outcomes for operative and nonoperative management of asymptomatic cholelithiasis in patients awaiting renal transplantation. METHODS: A retrospective chart review of all patients who received renal transplant at the authors' institution during the period 1994 to 2000 was completed. All patients underwent pretransplantation abdominal ultrasound. RESULTS: Of the 411 patients receiving renal transplants (242 men and 169 women with a mean age of 45.7 years), 32 had cholelithiasis at the pretransplantation workup (7.8%), and 35 had gallbladder abnormalities (8.5%): polyps, thickened wall, sludge, bile duct dilation. Before transplantation, 12 of the 32 patients (38%) with cholelithiasis underwent uncomplicated cholecystectomy. None of the remaining 19 patients with cholelithiasis required cholecystectomy after renal transplantation (mean follow-up period 6.2 years). Of the 35 patients with gallbladder abnormalities, 2 required post transplantation elective cholecystectomy. CONCLUSIONS: No evidence was found for increased morbidity related to cholelithiasis or gallbladder abnormalities after renal transplantation. As in the general population, the risks associated with asymptomatic cholelithiasis do not appear to warrant prophylactic cholecystectomy for patients awaiting renal transplantation.

Adult↗
PubMed1998

Is there any association between the presence of bone disease and cumulative exposure to lead?

There is evidence from cell culture experiments, animal studies, and from measurements in humans that lead may exert detrimental effects on bone mineral metabolism. In order to explore a possible association between lead and bone disease, both cortical and trabecular bone lead content as well as serum lead concentration was measured in 117 patients who attended a metabolic bone disease clinic (n = 92) or were undergoing dialysis for renal failure (n = 25). Cortical bone lead content was higher in patients suffering from Paget's disease than it was in controls, patients with osteoporosis, and patients on dialysis. Trabecular bone lead content was lowest in patients with Paget's disease or osteitis fibrosa. There was no association between bone lead content and serum alkaline phosphatase concentration in patients suffering from osteoporosis. No statistically significant differences in serum lead concentrations were found between groups. Our results do not distinguish between the two possibilities that increased bone turnover due to Paget's disease releases lead from trabecular bone which is then available for deposition into cortical bone or the alternative possibility that an increased lead content in cortical bone may cause increased turnover with release of lead from trabecular bone.

Aged↗
PubMed1978

The proper fit.

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PubMedDate not supplied

Design of parallel plate ion chambers for buildup measurements in megavoltage photon beams.

Dose measurements in the buildup region of megavoltage photon beams are most commonly made using parallel plate ion chambers having fixed electrode separation. Fixed-separation chambers generally do not read correctly under such beam conditions because of the contribution to the chamber signal of electrons from the side walls. In this work it is shown that the side wall error can be very large and published correction formulas are not accurate for all beam conditions and chamber geometries. The principal focus of this study has been to determine the design features of a fixed-separation chamber that has negligible side wall error. The approach has been to study, in beams of 60Co, 6 MV, and 18 MV, the response of a specially built ion chamber in which several chamber parameters could be independently varied. The study has shown that the side wall error is primarily dependent on the ratio of the electrode separation to the wall diameter as well as on the wall density and wall angle. Based on these findings the design of a fixed-separation chamber is described which reads to within about 1% of the correct dose. Guidelines are also provided for assessing the suitability of current commercial fixed-separation ion chambers for buildup measurements.

Cobalt Radioisotopes↗