Search PubMed⌕ Search

Biomedical subjects

R C Brown

Publications and source records attributed to R C Brown.

At least 163 records · Page 9Linked to original sources
PubMed1986

Driving safety and adolescent behavior.

Accidents, and mainly automotive accidents, are currently the leading cause of mortality and morbidity among young people. Understanding and addressing the issue of automotive accident prevention requires an awareness of the multiple psychodynamic, familial, and societal influences that affect the development and behavior of adolescents. Risk-taking behavior is the product of complex personal and environmental factors. As pediatricians, we have the obligation and the opportunity to improve the safety of our youth who drive and ride. This opportunity is available to us not only in our roles as counselors to youth and families, but also as we serve as role models, educators, and agents for change within our communities.

Accidents, Traffic↗
PubMed1985

A study of vitamin D levels in Indonesian patients with untreated pulmonary tuberculosis.

The levels of serum vitamin D, measured as 25-hydroxycholecalciferol (25-OHD3), among 40 Indonesian patients with pulmonary tuberculosis and 38 healthy controls were very similar. In both groups the distribution of the serum 25-OHD3 levels were bimodal with about a quarter of the individuals belonging to the group with higher levels. There was a tendency for controls in this group to be tuberculin negative and for patients in this group to have less extensive active pulmonary disease. Although it is uncertain whether such associations result from a direct effect of vitamin D on protective immune reactions, the use of this vitamin as an adjunct to antituberculosis therapy merits consideration.

Adolescent↗
PubMed1985

The value of post-void radiographs in excretory urography.

For years, urologists and radiologists have had differing opinions on the value of post-void radiographs in excretory urography. This report is based on a questionnaire sent to the members of the Association of University Urologists and the Society of Uroradiologists. Satisfactory evaluation of bladder function by the use of post-void radiographs is not always possible. Nevertheless, such radiographs have value in selected cases and often play a major role in determining future therapy.

Adult↗
PubMed1985

Effect of dietary calcium and phosphorus depletion on vitamin D metabolism and calcium binding protein in the growing pig.

Twenty-four young pigs were divided into three groups and each fed a replete, low calcium (Ca) or low phosphorus (P) diet. It was found that the deficient diets induced rises in renal 25 hydroxy-vitamin D 1,hydroxylase (1-hydroxylase) activity, circulating 1,25 dihydroxy-vitamin D3 (1,25 (OH)2-D3) and Ca binding protein (CaBP) and intestinal 1,25(OH)2D3 and CaBP. All these rises were statistically significant in the low Ca group but only the rises in the 1-hydroxylase activity and intestinal 1,25(OH)2D3 were significant in the low P group. A high degree of correlation existed between the parameters. There was no enhancement of intestinal 1,25(OH)2D3 or CaBP concentration relative to the 1-hydroxylase activity in the low P pigs as occurs in the chick. The low-P-induced rise in 1-hydroxylase activity was independent of parathyroid hormone.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1985

In vitro biological effects of volcanic ash from Mount Sakurajima.

Mount Sakurajima in the south of the Kyushu Island of Japan erupts hundreds of times a year and continuously emits large amounts of ash. More than a million people live under this ash plume, and there is considerable concern about the possible effects of this on their health. We have studied the physicochemical characteristics and in vitro effects of airborne ash collected at 8 km from the crater. More than 30% of the ash was found to be SiO2 (w/w) with most of the particles within the respirable size range. The ash did not inhibit the colony formation of V79-4 cells and failed to activate complement or generate chemotactic factor activity in samples of fresh human serum. It was minimally active in causing the release of lysosomal enzymes from human neutrophile, and did not cause arachidonic acid release from macrophage-like cells. These results were in accord with our epidemiological study, in which very low prevalences of nonspecific respiratory disease were demonstrated even at the area with highest ash exposure.

Air Pollutants↗
PubMed1985

The influence of long-term cimetidine as an adjuvant to pancreatic enzyme therapy in cystic fibrosis.

Seventeen patients on constant doses of pancreatic enzymes were randomised to receive either cimetidine or placebo for either of two successive six month periods. Nutritional state and maldigestion were assessed at the beginning and end of each period. Reductions in mean values of faecal fat, nitrogen, wet weight, and bile salts of approximately 30% were found on cimetidine therapy. Results showed considerable variation and only the fall in faecal fat was statistically significant. No benefit was demonstrated for height, weight, skinfold thickness, albumin, vitamin A, bone age or Crispin-Norman score.

Adolescent↗
PubMed1985

Serum concentrations of vitamin D metabolites in untreated tuberculosis.

A prospective study of 50 consecutive patients presenting with tuberculosis has shown that patients have on average lower serum concentrations of 25-hydroxycholecalciferol (25-OHD) than healthy matched controls. No difference was shown in serum 1,25-(OH)2D, 24,25-(OH)2D, or parathyroid hormone. Uncorrected serum calcium was lower in the patient group but identical when correction concentrations were made for albumin. Serum liver enzyme concentrations were significantly higher in the patient population. Low serum vitamin D concentrations may be a consequence of disease. The possibility that low serum 25-OHD concentrations may predispose to tuberculosis infection cannot, however, be excluded. Prolonged treatment with isoniazid or rifampicin, both of which have been shown to reduce serum 25-OHD, may increase the risk of vitamin D deficiency and consequent osteomalacia in groups of patients most at risk, such as those of Indian subcontinental ethnic origin.

24,25-Dihydroxyvitamin D 3↗
PubMed1985

Collagen biosynthesis enzymes in lung tissue and serum of rats with experimental silicosis.

The activities of prolyl 4-hydroxylase, galactosylhydroxylysyl glucosyltransferase (GGT) and lysyl oxidase (three enzymes catalysing post-translational modifications of collagen) were measured in the lungs of rats exposed to silica (DQ12). Circulatory levels of GGT were also estimated. Rats were killed after 24 h and at 6, 12 and 24 weeks after a single intratracheal instillation of either 12.5 or 25 mg of silica (DQ12). Control animals received saline. The total activity of the three enzymes in the lungs of the exposed animals was significantly increased at all times (P less than 0.05). The circulatory levels of GGT were also increased though some differences failed to reach significance. Thus increased activities of enzymes of collagen biosynthesis correlated with the development of silicosis and occurred within 24 h of treatment. This suggests that the changes responsible for the eventual development of fibrosis are operative within hours of dust exposure.

Aging↗
PubMed1985

Specimen xeroradiography after needle localization and biopsy of noncalcified, nonpalpable breast lesions.

Xeroradiography was used to detect and aid in needle localization of 63 nonpalpable breast lesions over an 8-year period. In 28 patients (44%), no microcalcifications were present in the lesion biopsied. Xeroradiographs of these noncalcified lesions after their submersion in water carried a clean and close resemblance to their in vivo appearance and aided the pathologist in localizing the abnormality within the biopsy specimen. This simple method improved the accuracy of the needle-guided biopsy while allowing excision of minimal breast tissue. A total of 17 (27%) lesions revealed malignancy. At the time of mastectomy, all carcinomas were at an early stage with no nodal involvement. No recurrence has been detected to date with a mean follow-up period of 24 months. This procedure requires close cooperation between the surgeon, radiologist, and pathologist.

Adult↗
PubMed1985

Radiologic appearance of the upper cervical canal in women with a history of premature delivery.

The aim of this study was to compare the radiologic appearance of the upper cervical canal at hysterography between a group of women with a history of premature delivery and a control group. A standardized technique was used that corrects for the magnification inherent in taking measurements directly from the x-ray films. Some women with a history of premature delivery had abnormally wide upper cervical canals in the nonpregnant state. Premature labor might not have been an acute pregnancy-specific event in those women but might have been a reflection of an underlying abnormality.

Cervix Uteri↗
PubMed1984

Arachidonic acid release and prostaglandin synthesis in a macrophage-like cell line exposed to asbestos.

A macrophage-like cell line (P388D1) has been treated with asbestos and the release of arachidonic acid and its metabolites has been studied using two methods. In the first monolayer cultures of the cells were labelled with tritiated arachidonic acid and the release of label into the medium was quantified: secondly the synthesis and release of prostaglandins E2 and F2 alpha were followed using radioimmune assay. Crocidolite asbestos caused the greatest release of tritium while the medium from chrysotile-treated cultures contained more of both prostaglandins. Both of the fibrous dusts were significantly more active in both test systems than were the two 'inert' materials--titanium dioxide and milled sample of crocidolite. It is suggested that these phenomena are due to the effect of mineral dusts on phospholipase activity and that differences in this activity are associated with differences in the pathogenicity of various mineral dusts.

Arachidonic Acid↗
PubMed1984

The metabolism of benzo(a)pyrene by the lungs of asbestos exposed rats.

A group of Fischer F344 rats were exposed to an aerosol of crocidolite asbestos for 36 d. Short-term organ cultures were established from the lungs of these animals and from a similar control group. The ability of these cultures to metabolise benzo(a)pyrene to water-soluble and ether-soluble forms was measured. Crocidolite treatment reduced the lungs ability to produce both types of metabolite although only the reduction in water-soluble forms was significant. DNA binding increased in cultures from treated rats, though this was not statistically significant. The possible relationship of these results to asbestos pathogenesis is discussed.

Animals↗
PubMed1984

Magnesium absorption from the digestive tract of sheep.

Factors affecting absorption of Mg from the ovine rumen have been studied using either a pouch constructed from part of the dorsal rumen or by an isolated washed rumen technique in vivo. Net absorption of Mg against the prevailing electrochemical gradient was observed. An increase in the K/Na ratio within the rumen led to an increase in the potential difference across the rumen wall, blood positive, and to a decrease in the net efflux of Mg from the rumen. This decrease was due to an increase in Mg influx into the rumen. The addition of ammonium chloride (30 mmol/l) to the rumen contents also led to a reduction in net Mg absorption but to no significant change in potential difference. The effects of high K/Na ratio and high ammonium ion concentration within the rumen were additive in causing decreases in net effluxes of both Mg and Na. An inverse relationship was demonstrated between the Ca concentration in the rumen and the net absorption rate of Mg. It was concluded that the efflux of Mg across the rumen wall depends at least in part on a functional system for Na transport.

Absorption↗
PubMed1984

Ultrasonography of the pancreas, liver, and biliary system in cystic fibrosis.

Abdominal ultrasound imaging was performed in 50 children. Thirty nine were proved to have cystic fibrosis while 11 had respiratory infections and thus acted as controls. The pancreas was abnormal in 75% of cystic fibrosis patients aged under 5 years and in 95% over 5 years. In cystic fibrosis patients over 5 years old who had malabsorption, the pancreas was abnormal in 100%. Abnormalities of the liver parenchyma were found in 23%, of the gallbladder in 24%, and splenomegaly in 8% of the cystic fibrosis patients.

Adolescent↗