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Biomedical subjects

R G Roy

Publications and source records attributed to R G Roy.

At least 19 recordsLinked to original sources
PubMed1992

Effect of titanium endoprostheses on bone mineral density measurements, using quantitative computed tomography.

Quantitative computed tomography has been used extensively to measure bone mineral density; particularly in the vertebral column and in the proximal portion of the femur in human beings with osteoporosis. Other potential applications of this technique include evaluation of bone adjacent to metallic endoprostheses and evaluation of fractures as they heal. Unfortunately, metal causes severe image degradation, principally seen as starburst streaking. One method used to decrease these artifacts is by imaging less-attenuating materials, such as titanium alloy. Titanium decreases image degradation sufficiently to allow accurate determination of the geometric properties of cadaveric bone. In our study, the effect of a titanium segmental endoprosthesis on bone mineral density measurement was determined by use of bone specimens from dogs and calibration standards. Titanium decreased the bone mineral density of calibration solutions from 6.8 (500 mg/cm3) to 17.7% (250 mg/cm3), and increased bone mineral density of cortical bone by 5.3%. Titanium did not affect the repeatability of these scans, indicating that the error caused by titanium was systematic and can be corrected. Our data were suggestive that quantitative computed tomography can be used to measure bone mineral density of cortical bone adjacent to titanium endoprostheses, with a predictable increase in density measurement.

Animals↗
PubMed1988

A double-blind controlled clinical trial to assess the role of anti-histamines in the treatment of multi-bacillary leprosy.

A double blind controlled clinical trial to assess the role of anti-histamines as a supplement in the treatment of leprosy was conducted in multi-bacillary cases of leprosy. In all, 120 patients with lepromatous or borderline leprosy were randomly allocated to a regimen of clofazimine and dapsone for 12 months with or without a supplement of pheniramine maleate for the first 3 months. During the 12-month period, 92% of the patients who received the supplement and 86% of the patients who had not received it had moderate or marked clinical improvement. The BI values decreased from 4.1 to 3.4 and 4.2 to 3.3, respectively. The results over the 12-month period showed that the addition of the antihistamine had not enhanced the efficacy of the regimen as evidenced by clinical and bacteriological findings.

Adolescent↗
PubMed1987

Preparation of a monoclonal antibody to a melanoma growth-stimulatory activity released into serum-free culture medium by Hs0294 malignant melanoma cells.

Autostimulatory growth factors may contribute to the ability of malignant cells to escape normal growth controls. We have previously shown that Hs0294 human malignant melanoma cells release into culture medium an acid-soluble, heat-stable, trypsin-sensitive, autostimulatory monolayer mitogen which can be purified from acetic acid extracts of conditioned medium by gel filtration, reverse-phase high-performance liquid chromatography, and preparative electrophoresis. The majority of this melanoma growth-stimulatory activity (MGSA) resides in a 16-Kd moiety, though bioactivity is also associated with 24-26 and less than 14-Kd forms of MGSA (Richmond and Thomas: J Cell Physiol 129:375, 1986). In order to further characterize this growth factor, monoclonal antibodies were prepared against a partially purified preparation of the autostimulatory melanoma mitogen. Monoclonal antibody clones were selected based on supernate inhibition of 3H-thymidine incorporation in serum-free Hs0294 melanoma cultures. One of these, termed FB2AH7, slows, but does not completely block, the growth of Hs0294 cells in serum-free medium in a dose-dependent manner. This antibody does not slow the growth of normal rat kidney fibroblasts, which neither produce nor require this mitogen, in either serum-free medium or medium containing 0.8% calf serum. This monoclonal antibody also blocks the mitogenic effects of partially purified preparations of this melanoma growth stimulatory activity (MGSA) on both Hs0294 cells and normal rat kidney fibroblasts. The FB2AH7 antibody has been demonstrated to bind MGSA by Western blot and by immunoprecipitation procedures. Western blot analysis of reverse-phase high-performance liquid chromatography purified growth factor demonstrated that FB2AH7 antibody binds to the 16-Kd and approximately 13-14-Kd forms of MGSA. FB2AH7 antibody can be used in immunoprecipitation experiments to bind the approximately 13-16-Kd forms of MGSA. The specificity of the binding of FB2AH7 antibody for MGSA but not other growth factors has been demonstrated in a modified dot blot assay. These data thus support the hypothesis that MGSA is an autostimulatory melanoma mitogen distinct from other growth factors.

Animals↗
PubMed1984

Characteristics and correlates of effective and ineffective social supports.

The paper examines cohorts of individuals with helpful and unhelpful social supports identified in a longitudinal study of stressful events, social supports and health. Specific features of the quantity and quality of social relationships leading to help and support are examined. Individuals with helpful social supports describe their social networks as smaller and appear to derive support primarily from spouse and close family relationships. No significant differences in the number of multiplex and reciprocal relationships were found. Subjects reporting the least helpful social supports also reported significantly more stressful events in the past five years and significantly more childhood events.

Adult↗
PubMed1984

Plasma cysteine, cystine, and glutathione in cirrhosis.

Plasma contains three forms of cyst(e)ine: cysteine, cystine, and protein-bound cysteine. The former is a thiol and the latter two are disulfides. The levels of all three types of cyst(e)ine, as well as the cysteinyl tripeptide glutathione, were measured in the plasma of 14 normal and 10 cirrhotic individuals. All subjects ate mixed foods. Some cirrhotic patients were studied during nasogastric hyperalimentation with Vivonex (Norwich Eaton Pharmaceuticals, Norwich, N.Y.) as well as during total parenteral nutrition with FreAmine III (American McGaw, Irvine, Calif.); neither formula contains cyst(e)ine. Regardless of the nature of the diet, cirrhotic patients had significantly subnormal values for cysteine, glutathione, and albumin. In addition, the following significant changes were found to be diet-dependent: (a) elevated methionine during Vivonex, (b) subnormal taurine during mixed foods and total parenteral nutrition, (c) depressed protein-bound cysteine during total parenteral nutrition, (d) depressed cyst(e)ine thiol/disulfide ratio during mixed foods, and (e) depressed total thiol during Vivonex and total parenteral nutrition. The data indicate multiple abnormalities in sulfur metabolism in cirrhosis.

Adult↗
PubMed1983

Heterogeneity in anticatalytic activity of antibody specific for horseradish peroxidase.

Rabbit antibodies specific for horseradish peroxidase are heterogeneous in their ability to inhibit enzyme activity. Heterogeneity was demonstrated by fractionation of the total antiperoxidase pool by differential ammonium sulfate precipitation and differential elution of antibody from enzyme affinity columns. Both fractionation methods yielded antibody subpopulations that differed in anticatalytic activity. Some antibody subpopulations decreased enzyme activity almost completely at low molar ratios of antibody to peroxidase. Other subpopulations were not effective inhibitors even at great molar excess. Admixture experiments demonstrated that inefficient antibody pools decreased the anticatalytic effect of highly inhibitory antibody. The degree of inhibition observed with unfractionated antiserum is a reflection of the interaction of various antibody subpopulations with the enzyme. No correlation was found between the immunoglobulin class of antiperoxidase and anticatalytic efficiency in analyses of numerous antisera. The determinant specificity of an antiperoxidase molecule determines its anticatalytic ability. A peptide fragment (mol. wt 22,500) of peroxidase prepared by partial tryptic digestion bount 60 to 70% of the total antiperoxidase in a number of antisera. However, the peptide did not bind inhibitory antibodies.

Animals↗
PubMed1983

Bacteriological study of trophic ulcers in leprosy patients (a preliminary study).

Swabs from trophic ulcers from 108 cases were studied by culture. 37 cases yielded single organism (Ps. aeruginosa, 18, Proteus species 11, Staph. pyogenes 4, Others 4). 71 cases yielded mixed growth with two or more organisms. Ps. aeruginosa, Proteus species and Diphtheroids were the predominant organisms in these cultures. Ps. aeruginosa was sensitive to Gentamycin (96.6%), Streptomycin (62.7%) and Chloramphenicol (33.9%). Other organisms although comparatively more sensitive showed a similar pattern.

Actinomycetales↗
PubMed1981

Quality of life events and their relationship to strain.

The traditional view of life events is that the crucial factor is the number which occur within a defined time period. This was examined as part of a 2-year, prospective, longitudinal study of prospective, longitudinal study of 518 people, each of whom was interviewed every 6 months with Holmes and Rahe's Recent LIfe Change Questionnaire (RLCQ). The subject was asked if each event was anticipated or unanticipated, desirable or undesirable, and controllable or uncontrollable. Desirable, controlled, or anticipated ("positive") events did not correlate with strain, as measured by Langner's scale; whereas undesirable, uncontrolled, and unanticipated ("negative") events did. Subjects whose RLCQ scores comprised at least 75 percent positive events had significantly lower Langner scores than subjects with equivalent RLCQ totals, primarily negative ones.

Adult↗
PubMed1981

Methodological issues in developing a scale to measure social support.

In recent years there has been considerable research and clinical interest in developing instruments to assess social supports available to individuals. There is, however, a notable deficiency of attempts to evaluate the psychometric properties of these questionnaires. The present article describes efforts made to evaluate the properties of a Social Relationship Scale (SRS) that was developed as part of a prospective study of the psychosocial influences on the health status of a population. Some descriptive scale statistics are also presented.

Female↗