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Biomedical subjects

M Cosma

Publications and source records attributed to M Cosma.

At least 19 recordsLinked to original sources
PubMed2003

Commissioning and clinical results utilizing the Gildenberg-Laitinen Adapter Device for X-ray in fractionated stereotactic radiotherapy.

BACKGROUND: The Gildenberg-Laitinen Adapter Device for X-Ray (GLAD-X/LS) frame is a positioning device that allows the use of the same fiducial points as the Brown-Robert-Wells (BRW) system. Thus it permits treatment planning to be accomplished by the Radionics X-knife Radiosurgery Program. We investigated the commissioning and clinical benefits of the GLAD-X/LS for fractionated stereotactic radiotherapy (FSRT) in patients who were unable to tolerate the Gill-Thomas-Cosman (GTC) frame. METHODS AND MATERIALS: Commissioning of the GLAD-X/LS system was done via use of a Rando Phantom. A target volume of 2 x 2 x 2 cm was drilled into the phantom head. An ion chamber and thermoluminescence dosimetric chips (TLDs) were implanted in the target. A simulated treatment course consisting of 5 stereotactic radiotherapy fractions (300 cGy, 30 mm collimator) was delivered to the phantom head. A total of 27 patients who could not tolerate the GTC frame were treated using the GLAD-X/LS system. A total of 35 isocenters were used; the median number of treatment fractions was eight. Reproducibility of the x, y, and z coordinates was examined and correlated to the same determined using orthogonal port films. Relocation accuracy and reproducibility were further assessed comparing the x, y, and z coordinates of the target center with multiplanar reconstructed coronal and sagittal images. Patient tolerance of the device was also evaluated daily throughout the treatment. RESULTS: The measured TLD and ion chamber doses were within 3% of the prescribed dose at the isocenter. The same dose accuracy was also found at incremental distances of 5 mm, 10 mm, and 15 mm from the isocenter. All patients tolerated the treatment and the device well. Six patients experienced mild ear canal pain, and softer or smaller earpieces were substituted. The mean relocation accuracy was 1.5 mm +/- 0.8. CONCLUSIONS: The GLAD-X/LS system has excellent accuracy and reproducibility with the mean relocation accuracy of 1.5 mm +/- 0.8. The device is well-tolerated by patients, with no significant complications. Larger scale studies are necessary before routine use can be recommended for the administration of FSRT.

Brain Neoplasms↗
PubMed2001

Diet acids and alkalis influence calcium retention in bone.

The urine-acidifying properties of food constituents depend on their content of non-oxidizable acids or precursors. Acidifying constituents such as animal proteins may negatively affect calcium metabolism and accelerate bone resorption, thus representing an aggravating factor for osteoporosis. This four-period, double-crossover study investigated whether a diet intervention specifically focused on acid load could modify calcium metabolism in humans. Eight healthy volunteers underwent a four-day metabolic preparation with two types of diets, one rich in acid ash-forming nutrients, and one providing base-forming nutrients (including bicarbonate-rich mineral water), both having similar contents of calcium, phosphate, sodium, proteins and calories. On the fourth day, a single oral dose of 1 g calcium was given, either as carbonate or as gluconolactate. Serial blood and urine samples revealed that the diet affected blood pH (average difference 0.014, p=0.002) and urine pH (average difference 1.02, p<0.0001) in the expected direction, but had no influence on the absorption of the calcium supplement. The acid-forming diet increased urinary calcium excretion by 74% when compared with the base-forming diet (p<0.0001), both at baseline and after the oral calcium load, and C-telopeptide excretion by 19% (p=0.01), suggesting a skeletal origin for the excess calcium output. This observation confirms that renally excreted acids derived from food influence calcium metabolism, and that alkalizing nutrients inhibit bone resorption. Further studies are needed to determine the clinical impact of dietary counseling for avoiding diet acids as a preventive measure against osteoporosis.

Acids↗
PubMed2001

Nonreferral and nonacceptance to dialysis by primary care physicians and nephrologists in Canada and the United States.

Research from Canada and the United States suggests that not offering dialysis to patients who might benefit still occurs. This study was conducted to investigate nonreferral and nonacceptance to dialysis by primary care physicians (PCPs) and nephrologists in these countries. We surveyed a random sample of Canadian and US PCPs and nephrologists concerning their attitudes toward and experience with withholding dialysis in patients with advanced chronic renal failure. In response to a question about whether the physician believes there should be an age beyond which dialysis should not be offered, 12% of Canadian PCPs, 20% of US PCPs, 4% of Canadian nephrologists, and 9% of US nephrologists answered yes. When asked about their recommendations concerning dialysis initiation in 10 vignettes of patients with impending end-stage renal disease (ESRD), the responses of Canadian and US physicians were similar. PCPs compared with nephrologists were less likely to recommend dialysis in cases with physical illnesses and more likely to recommend it in cases with neuropsychiatric impairments. Over a 3-year period, 13% of Canadian PCPs and 19% of US PCPs reported nonreferral to dialysis at least once. Withholding rates were 25% for Canadian PCPs, 16% for US PCPs, 13% for Canadian nephrologists, and 17% for US nephrologists. We conclude that although nonreferral of patients who might benefit from dialysis still occurs, it does not seem to be common, and the attitudes of Canadian and US physicians toward this issue are similar and could not entirely account for the much greater incidence of treated ESRD in the United States. PCPs and nephrologists should continue to be educated about the modern criteria for patient selection for dialysis.

Adult↗
PubMed1995

Practice model: development of a nurse-managed unit and the advanced practitioner role.

Health care reform has provided opportunities for the creation of nurse-managed centers and the expansion of an autonomous nursing role. This article describes a program established by Massachusetts General Hospital for cardiac patients that has reduced delays in transfer and improved access to the hospital from referral centers. The program merges a strong primary nursing staff with a new advanced practice nursing role to create an alternative to the traditional model of inpatient care.

Heart Diseases↗