Search PubMed⌕ Search

Biomedical subjects

R W Brown

Publications and source records attributed to R W Brown.

At least 127 records · Page 7Linked to original sources
PubMed1985

Physiological characteristics of Streptococcus dysgalactiae and Streptococcus uberis and the effect of the lactoperoxidase complex on their growth in a chemically-defined medium and milk.

Aerobic or anaerobic degradation of glucose by Streptococcus dysgalactiae and Streptococcus uberis yielded products qualitatively similar to those observed previously for Streptococcus agalactiae. There were, however, quantitative differences. Though acetoin was formed during aerobic growth of Streptococcus uberis, there was none with Streptococcus dysgalactiae. Differences between Streptococcus dysgalactiae and Streptococcus uberis in their aerobic metabolism of glucose was in lower oxygen consumption (.5 mol/mol of glucose), greater conversion of glucose to lactic acid, and lower molar growth yields with Streptococcus uberis. Cell suspensions of Streptococcus uberis had strong peroxidase activity, and no hydrogen peroxide accumulated during the respiration on glucose. With Streptococcus dysgalactiae, there was more oxygen consumed during growth (1.5 mol/mol of glucose used), greater conversion of glucose to acetic and formic acids and carbon dioxide, and a cell yield of about 6 g of dry cells more per mole of glucose than with Streptococcus uberis. This increase in molar growth yield with Streptococcus dysgalactiae over Streptococcus uberis could be nearly all accounted for by differences in the amount of substrate level adenosine triphosphate generated. Cell suspensions oxidizing glucose accumulated hydrogen peroxide and showed no peroxidase activity. Streptococcus dysgalactiae showed the same growth relationships in three milk media as Streptococcus agalactiae, although growth and acid formation values were much lower. Growth inhibition by the lactoperoxidase complex was reversed with cystine. Acid formation by Streptococcus uberis was decreased by the lactoperoxidase complex and increased by the addition of cystine; however, neither appeared to affect the growth of the organism.

Animals↗
PubMed1984

Histologic appearance of the bilaminar zone in internal derangement of the temporomandibular joint.

Light microscopy was used to examine twenty-six specimens of bilaminar zone tissue excised during surgery for correction of internal derangement of the temporamandibular joint. Each of the specimens was examined for the presence of inflammation, amount of vascularity, arterial wall thickness, presence of fat, appearance of collagen, and amount of elastin present. Wide variation in the histologic appearance was noted among the specimens, although no significant inflammation was observed in any of them. Some indications that this tissue is undergoing adaptive changes include the presence of thickened arterial walls suggesting a decreased blood flow and the tendency for decreased amounts of elastin to be associated with denser-appearing collagen. There is also a tendency for patients with complete dislocation to exhibit less elastin than those with partial dislocation of the meniscus.

Adolescent↗
PubMed1983

Polycythemia vera and glomerulonephritis.

Six patients with polycythemia vera and proteinuria are described. Three patients had histologically defined glomerulonephritis. It is proposed that there is an association between polycythemia vera and the development of glomerulonephritis. Possible pathogenetic mechanisms are discussed.

Adult↗
PubMed1983

Fractionation of a whey growth factor for Streptococcus agalactiae into two active components containing proteins.

Previously three factors (F-1, F-2, F-3) that stimulated in vitro growth of Streptococcus agalactiae were separated from wheys of milk and colostrum by chromatographic procedures. Now F-1 was separated further into two active components, F-1a and F-1b, when rechromatographed on an anion exchange resin with distilled water as eluent. The stimulatory activity was associated with two protein peaks whereas a third protein peak that was eluted in those fractions containing lactose was not stimulatory. Most of the stimulatory activity (76 to 80%) and protein (90 to 93%) were retained by a filter with retention of greater than 1,000 MW. Two stimulatory factors were confirmed by separation of F-1 fractions by step-gradient elution on a column of octadecylsilica; one protein peak was found for each of the three solvents. Samples with protein eluted with .1 N formic acid and formic acid: methanol (1:1) had stimulatory activity, whereas the sample with protein eluted with 100% methanol was inactive. Results were similar when F-1 fractions were applied to Sep-Pak (muBondapack C18) cartridges and eluted with water, 50% methanol, and 100% methanol. Proteins in the Sep-Pak eluates with stimulatory activity (water and 50% methanol) were heterogeneous and different when separated by high-voltage paper electrophoresis. Proteose-peptone preparations with added lactose were chromatographed on columns of anion exchange resin, with distilled water as eluent, and produced two peaks of protein with elution volumes comparable to peaks 1 and 3. Lactose appeared to be a major factor in eluting the second protein peak.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Biotypes of Staphylococcus epidermidis and Micrococcus organisms, isolated from intramammary infections, reclassified into species of the genus Staphylococcus (epidermidis, hyicus, xylosus, and sciuri).

In a previous report (5), strains of Staphylococcus epidermidis and Micrococcus isolated from bovine intramammary infections were classified by the Baird-Parker (B-P) system and by serologic typing of the proteolytic enzymes. Since then, newer methods for distinguishing the genera Staphylococcus and Micrococcus and for defining new species have been reported. By utilizing these methods, the organisms from the original study were reclassified as follows: S. epidermidis B-P subgroup II, proteinase group F strains as S. epidermidis; S. epidermidis B-P subgroup III, proteinase group B strains as Staphylococcus hyicus subsp. chromogenes (pigmented) or subsp. hyicus (nonpigmented) and proteinase groups H and BH strains that were coagulase positive and nonpigmented as subsp. hyicus; B-P Micrococcus subgroup 6, proteinase group NR strains as Staphylococcus xylosus and subgroup 6, proteinase group G strains as Staphylococcus sciuri and S. xylosus. The reclassification of the strains increased the percentage of intramammary infections attributed to staphylococci from 62%, as first reported, to at least 86%.

Animals↗
PubMed1983

Incidence of perilobular hemangioma in the female breast.

The perilobular hemangioma is generally considered uncommon. We found a high incidence (11%) of this little-recognized benign mammary lesion during the course of a recently completed autopsy study designed to assess bilateral, four-quadrant, and subareolar disease of the breast in 210 consecutive forensic post-mortem examinations on female subjects between 15 and 97 years of age. Despite the lesion's name, its distribution was found to involve any of the stromal components of the breast. The unexpected frequency of the perilobular hemangioma within breasts in this study and the reported rarity of mammary angiosarcomas indicate that malignant transformation, if it occurs, must be rare.

Adolescent↗
PubMed1982

Breast tumors in patients with hyperprolactinemia.

The histology of breast lumps in five patients with hyperprolactinemia showed benign mammary dysplasia with vacuolation of acinar and duct lining cells. In two cases, foci of lobular development resembling lactating breast tissue were also noted. In the past, focal secretory change has been considered to be idiopathic, but these cases indicate a possible association with hyperprolactinemia. Among other causes hyperprolactinemia may be a manifestation of occult pituitary adenoma. Therefore it is suggested that patients with benign breast nodules showing focal secretory change should be screened for clinical and laboratory evidence of hyperprolactinemia. Although it is accepted that in mice and rats prolactin plays an important role in chemically induced mammary tumorigenesis, a consensus has not been reached with regard to its role in man.

Adult↗
PubMed1982

Multiple bilateral angiolipomas of the breast: a case report.

Angiolipoma, a benign mixed connective tissue tumour which is uncommon in the breast, may be confused clinically, radiologically and pathologically with malignant lesions. An unusual case of multiple, bilateral angiolipomas appearing synchronously and metachronously in the breasts of a 75 year old woman is presented. The apparent recurrent nature of these tumours is considered to result from a change in multiple, pre-existing but previously impalpable tumours in both breasts.

Aged↗
PubMed1982

Effect of time of sample collection, milk composition, and stage of lactation on the growth-promoting properties of milk for Streptococcus agalactiae.

Milk samples were taken from noninfected mammary quarters before the AM milking and at intervals after milking. The pH values of the post-AM milk samples were higher than the AM foremilk samples for approximately 3 to 6 hours after milking. When these samples were pasteurized, inoculated with a culture of Streptococcus agalactiae, and incubated at 37 C for 24 hours, there was a greater pH change (delta pH) in the post-AM milks. The higher pH and delta pH values of 3-hour samples coincided with higher concentrations of bicarbonate and chloride, lower concentrations of citrate and phosphate, and lower titratable acidities. Milk samples were taken before the AM milking and 3 to 4 hours later from 2 noninfected quarters of each of 2 cows at weekly intervals for 9 months. The growth of S agalactiae in the milk samples showed that the delta pH and bacterial counts (i) increased as the lactation progressed and milk yield decreased, (ii) were higher in he 3- to 4-hour samples than in the AM samples, and (iii) were higher in the whole milk than in the skim milk of the 3-to 4-hour samples; this difference was attributed to the cream layer and in most instances could be duplicated by layering liquid petrolatum on the surface of skim milk. Also, the bacterial counts in the 3- to 4-hour skim milks were higher than those of the corresponding AM skim milks in 78% of the paired samples, which indicated that another factor, in addition to the cream layer, might be involved in promoting better in vitro growth of S agalactiae in the 3 to 4-hour milk.

Animals↗
PubMed1981

Bacteremia and bacteriuria after transrectal prostatic biopsy.

To determine the efficacy of parenteral gentamicin versus povidone-iodine enema (P.I.E.) in preventing infectious complications, a randomized study was undertaken in 40 patients undergoing transrectal needle prostatic biopsy. In 69 per cent of patients not receiving P.I.E. bacteremia developed, and 32 per cent acquired bacteriuria; whereas only 19 per cent of patients given P.I.E. alone or in combination with gentamicin because bacteremic, and 9.5 per cent had postbiopsy bacteriuria. Thus, P.I.E. provided a safe and effective means for preventing most bacteremia and bacteriuria associated with transrectal biopsy of the prostate.

Adult↗
PubMed1981

Life events and chronic duodenal ulcer: a case control study.

The frequency of life events during the two years before an exacerbation of ulcer in a duodenal ulcer population was compared with the frequency of these events over the same time period in an age-sex matched probability sample of the community population. The mean number of events and the associated distress and life change scores were similar for both groups. When events were categorised into areas of activity, such as health, bereavement, family and social life, change of residence, etc. and were further classified on the basis of desirability, separation from persons, and problem chronicity, only one significant difference was found between patients and controls-more patients changed residence (p=0.0005). Frequency distributions of the number of events and the distress and life change scores were similar for both groups. Concerning individual events, the only significant differences in frequency were that more patients changed residence in Sydney (p=0.006) and more controls had a child leave home for reasons other than marriage (p=0.03). Patients and controls experienced the same four most frequent events. Among patients, no correlation existed between age and either the number of events experienced or distress and life change scores. Among controls, age was negatively correlated with the number of events experienced (p=0.0004) and the life change scores (p<0.003). It is concluded, therefore, that an excess of stress, as measured by the number of life events experienced and by distress and life change scores associated with these events, does not appear to be a risk factor for the exacerbation of chronic duodenal ulcer.

Adult↗
PubMed1981

Effect of epidermal growth factor on proliferation of human tumor cells in soft agar.

The effect of epidermal growth factor (EGF) and fibroblast feeder layers on the proliferation of human tumor cells in soft agar was examined. The addition of EGF to medium supporting growth of tumor cells significantly increased (P less than or equal to 0.02) the number of colonies grown from the cells of 36 to 58 patients (62%) with a variety of neoplasms. The increase in the number of colonies was dependent on the concentration of EGF and was maximal at a concentration of 50 ng EGF/ml. The addition of glucocorticoids did not potentiate the effect of EGF. Lethally irradiated fibroblast feeder layers alone only slightly increased the number of colonies. However, the addition of fibroblasts to cultures significantly increased the mitogenic effect of EGF. The results suggest that a proportion of epithelial-derived tumors retain responsiveness in vitro to physiologic growth regulators such as EGF.

Agar↗
PubMed1981

Effects of dietary aflatoxin on existing bacterial intramammary infections of dairy cows.

Aflatoxin, a naturally occurring mycotoxin with immunosuppressive properties, was given to 4 lactating dairy cows that had experimentally induced or naturally occurring mammary infections in 2 of their 4 mammary quarters. Aflatoxin was given orally in daily doses approximating 0.3 mg of B1 activity/kg of body weight for periods of 12 to 14 days. Infecting organisms were Streptococcus agalactiae, Staphylococcus aureus, and Staphylococcus hyicus. The 4 cows were monitored for clinical signs of disease and signs of mastitis for periods before, during, and after aflatoxin consumption. The cows developed inappetence, lost body weight, and had variable reductions in daily milk yield. Serum ornithine-carbamoyl transferase and sorbitol dehydrogenase activities were elevated during and 1 to 3 weeks after aflatoxin consumption. Exacerbations of acute clinical mastitis did not occur in any of the infected quarters; however, bacterial populations in the milk increased in 3 of the 4 cows during aflatoxin consumption. Mean California mastitis test scores were generally highest in the infected quarters in the period after the last dose of aflatoxin was given. Aflatoxin M1 appeared in milk 3 to 6 hours after aflatoxin consumption began, and persisted for 72 hours or longer after the last dose of aflatoxin was given. Aflatoxin B1 and M1 were present in urine samples taken at 6 hours after aflatoxin consumption began and persisted for 72 through 120 hours after the last dose of aflatoxin was given.

Aflatoxins↗
PubMed1980

Bacteremia after esophageal dilation: a clinical and experimental study.

Patients with esophageal stricture caused by caustic ingestion, reflux esophagitis, or esophageal anastomosis often require repeated dilation. These patients frequently have a short febrile course after dilation. After development of brain abscess following esophageal dilation in 1 patient, positive blood cultures were obtained in 4 patients immediately following esophageal dilation. Caustic strictures were produced in cats and esophageal dilations performed. Blood cultures were positive at one minute after dilation in 6 cats and at five minutes in 2 of those cats. The organism responsible in all clinical and three of four experimental examples was Staphylococcus aureus. It is suggested on the basis of this clinical and experimental data that patients undergoing esophageal dilation should have prophylactic coverage if they are immunosuppressed, if endocarditis prophylaxis is necessary, if they are infants, if they are diabetic, or if they had severe bacteremia following dilation.

Animals↗
PubMed1979

Lactoperoxidase, thiocyanate, and free cystine in bovine mammary secretions in early dry period and at the start of lactation and their effect on Streptococcus agalactiae growth.

The concentrations of lactoperoxidase (LP) and thiocyanate (SCN-) in the mammary secretions of 4 dairy cows in the early dry period were similar to or higher than concentrations in the milk before drying off. The concentrations of free cystine progressively increased in the secretions beginning 3 to 5 days after the last milking; the mean concentrations were 0.66 mumoles/L before drying off and 6.66 mumoles/L after drying off. The mean concentrations of free cysteine were 0.28 mumoles/L before drying off and 1.4 mumoles/L after drying off. The secretions, when diluted in steamed milk, showed greater stimulation of Streptococcus agalactiae growth as the drying-off period progressed. This increase in stimulatory activity was attributed primarily to the increased concentrations of cystine because cystine counteracts the LP/SCN-/hydrogen peroxide inhibitory system for S agalactiae. This effect on the LP system may account for any increase in susceptibility to S agalactiae under infection during the dry period. In 3 other cows, the mammary secretions on the day of calving had lower mean concentrations of LP, SCN-, and free cystine and cysteine than those obtained 4 to 5 days before, and 7 to 8 days after calving.

Animals↗