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Biomedical subjects

C C Brown

Publications and source records attributed to C C Brown.

At least 91 records · Page 5Linked to original sources
PubMed1991

Pathologic features of dogs inoculated with North American Trypanosoma cruzi isolates.

Twenty-three clinically normal Beagles were inoculated with North American Trypanosoma cruzi isolates from an opossum (Tc-O), an armadillo (Tc-A), or a dog (Tc-D). The dogs were grouped according to the clinical outcome of inoculation. Group 1 consisted of 7 dogs inoculated with Tc-O or Tc-A that died or were euthanatized during acute stages of disease. Group 2 consisted of 5 dogs inoculated with Tc-O or Tc-A, that also developed acute disease, but survived to develop chronic disease. Group 3 consisted of 7 dogs inoculated with Tc-D neither developed acute nor chronic disease. Group 4 consisted of 4 dogs and served as noninoculated controls. In group 1, the gross lesions were diffusely pale myocardiums with right ventricular enlargement, hepatomegaly, and a moderate amount of modified transudate in the abdominal cavity. Severe diffuse granulomatous myocarditis with large numbers of pseudocysts and minimal fibrosis characterized the tissues from all cardiac chambers and septum. The lesions were most severe in the right atrium and ventricle. Mild multifocal myositis and pseudocysts were observed in skeletal muscles and smooth muscles of the urinary bladder and small intestine. Multifocal encephalitis and pseudocysts were in the cerebral cortex, cerebellum, and brain stem. In group 2, the gross lesions were biventricular enlargement and thinning of the ventricular free walls. The right ventricle contained the most severe microscopic changes. There were mild multifocal interstitial lymphohistocytic cellular infiltrates, perivasculitis, and marked fibrosis in all areas of the myocardium. Mild myositis and multifocal encephalitis were seen in the skeletal muscles and brains. Pseudocysts were not observed in any tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

The lesions and prevalence of Trypanosoma cruzi in opossums and armadillos from southern Louisiana.

The prevalence of Trypanosoma cruzi in 48 opossums and 98 armadillos from southern Louisiana was studied. Sixteen opossums (33.3%) and 1 armadillo (1.1%) were positive for T. cruzi by blood culture. Hearts from 45 opossums and the tissues from the 1 blood culture-positive armadillo were available for histopathological examination. Although histopathology revealed T. cruzi pseudocysts in 6 opossums, 2 were not positive on blood culture. Therefore, 18 opossums (37.5%) were positive for T. cruzi. Twenty-two of 45 opossums had histological evidence of myocarditis. No lesion typical of infection with T. cruzi was observed in the armadillo tissues. These results substantiate that the opossum is a current reservoir host of T. cruzi infection in southern Louisiana and that armadillos may be of relatively minor importance.

Animals↗
PubMed1991

Detection of salivary HIV-1-specific IgG antibodies in high-risk populations in Zaire.

Saliva and blood samples were tested for human immunodeficiency virus-1 (HIV-1) antibodies in two high-risk populations in Kinshasa, Zaire. In a seroprevalence study of 458 sexually transmitted disease (STD) clinic attendees, 142 of 145 seropositive individuals had enzyme-linked immunosorbent assay (ELISA)-positive saliva samples (97.9% sensitivity). All saliva samples from seronegative patients were ELISA-negative (100% specificity). Of the 142 ELISA-positive saliva specimens, 137 were also Western blot-positive (94.5% sensitivity). In a subsequent seroincidence study of 315 initially seronegative female prostitutes followed during 183 woman-years of observation, 9 of 14 women who seroconverted (7.7% seroincidence) had ELISA-positive saliva samples at the time seroconversion was detected. Only three of these saliva specimens could be confirmed by Western blot. Although salivary testing for HIV-1 antibodies using conventional assays was not sensitive in detecting recent seroconversions, screening of salivary samples for HIV-1 antibody provides a convenient alternative method for conducting seroprevalence surveys in populations in whom venipuncture is not possible or convenient.

Adult↗
PubMed1990

Rise in prostatic cancer incidence associated with increased use of transurethral resection.

We examined the association between prostatic cancer incidence rates and the rates of transurethral prostatectomy to explore reasons for the nationally reported dramatic increases in incidence rates of prostatic cancer from 1973 through 1986. There was a strong correlation between both incidence of all stages of prostatic cancer combined and of localized disease and the increasing use of transurethral resection, a common surgical procedure usually performed to relieve urinary obstruction due to benign enlargement of the prostate. Our analyses suggest that increased detection of existing tumors via transurethral resection was the primary reason for the observed increase in incidence rates of prostatic cancer. However, analyses of mortality trends, particularly among nonwhites, and laboratory studies of the histologic nature of clinically asymptomatic tumors suggest that part of the increase may reflect changes in the real risk of prostatic cancer.

Age Factors↗
PubMed1990

Comparison of the descriptive epidemiology of urinary tract cancers.

We compared the descriptive epidemiology of several urinary tract cancers, utilizing incidence data from the United States and international sources. The patterns of cancers of the renal pelvis, ureter, and urethra were more similar to those of bladder cancer than to cancer of the renal parenchyma in several ways: (i) transitional cell carcinoma is the predominant histologic type in the renal pelvis, ureter, urethra, and bladder, whereas the vast majority of renal parenchyma neoplasms are adenocarcinomas; (ii) in situ tumors often appear in all these sites except the renal parenchyma; (iii) rate ratios for renal pelvis/ureter cancers among blacks and Hispanics, relative to whites, are closer to those for bladder than to those for renal parenchymal cancers; (iv) rates among US men and women for cancers of the renal pelvis and ureter are more highly correlated with those for bladder cancer than with those of the renal parenchyma across racial groups; and (v) similar correlations occur among women across geographic areas within the US and internationally. However, the patterns for cancers of the renal pelvis and ureter do not always resemble more closely those for bladder than renal parenchyma cancers and occasionally appear different from one another. These findings indicate the importance of distinguishing tumors based on specific primary site and cell type.

Adolescent↗
PubMed1990

Selenium intake, age, gender, and smoking in relation to indices of selenium status of adults residing in a seleniferous area.

Duplicate meals, serum, whole blood, and toenails were collected every 3 mo for 1 y from a group of 44 free-living adults residing in high-selenium areas of South Dakota and Wyoming to assess the relation of selenium intake to indices of selenium status. The average selenium values for the group were as follows: dietary intake, 174 +/- 91 micrograms/d (mean +/- SD), 2.33 +/- 1.08 micrograms/kg body wt; serum, 2.10 +/- 0.38 mumol/L; whole blood, 3.22 +/- 0.79 mumol/L; and toenails, 15.2 +/- 3.0 nmol/g. Selenium intake (micrograms/kg body wt) was strongly correlated (all values, P less than 0.01) with selenium concentration of serum (r = 0.63), whole blood (r = 0.62), and toenails (r = 0.59). Men and women had similar mean values of serum, whole blood, and toenail selenium despite higher selenium intakes in men. Smokers had lower tissue selenium concentrations than did nonsmokers due, at least in part, to lower selenium intake. Age was not associated with tissue selenium content. Of the variables examined selenium intake was clearly the strongest predictor of tissue selenium concentration.

Adult↗
PubMed1990

Variability in nutrient and food intakes among older middle-aged men. Implications for design of epidemiologic and validation studies using food recording.

The authors conducted a dietary methodology study in 1984 in Finnish men aged 55-69 years in order to validate two dietary assessment instruments being used in the US-Finland Alpha-Tocopherol, Beta-Carotene Lung Cancer Prevention Trial. Twelve 2-day food records collected from 162 men over a 6-month period, including every day of the week, served as the reference measure. This report focuses on three important questions for investigating diet and disease relations: 1) How many days are necessary to classify "usual" intake? 2) Is there loss as a result of using consecutive days? 3) Which days are necessary for assessment and classification of "usual" diet? A repeated-measures regression model was used to estimate the variance components and the effects of consecutive days, weekday (weekday vs. weekend), and season. Correlations between the averages of different numbers of days of food records and "true" usual intake were examined along with the resulting attenuations in relative risk. Results suggest that 7-14 days are required to adequately classify most individuals into categories of intake for most nutrients and some foods. There appears to be some loss of information from using consecutive days rather than days further apart. Weekday/weekend differences in mean intakes are slight, and the rank ordering of individuals appears to be preserved. A moderate seasonal effect is shown for classification of fruits, but only a slight one is seen for micronutrients and berries. Implications for the design of epidemiologic and validation studies are discussed.

Aged↗
PubMed1990

Infections of inbred mice with three Trypanosoma cruzi isolates from Louisiana mammals.

Trypanosoma cruzi isolates from a dog (Tc-D), opossum (Tc-O), and an armadillo (Tc-A) from southern Louisiana were inoculated into 6 inbred mouse strains. None of the isolates produced fatal infections in the mouse strains tested. Parasitemias were quantified over 34 days and found to be similar in mouse strains infected with Tc-O and Tc-A. Parasitemias in Tc-D-infected mice were detectable only by blood culture. Pseudocyst numbers, inflammatory changes, and weight changes were quantified in CF1 mice infected with the 3 isolates. Tc-O- and Tc-A-infected CF1 mice were shown to be myotropic and produced comparable weight increases, pseudocyst numbers, and inflammatory changes in similar tissues. Tissues found to contain pseudocysts were muscles of the bladder, abdominal wall, thigh, heart, and diaphragm. Clinical signs of infection, pseudocyst numbers, and inflammatory changes were minimal in Tc-D-infected CF1 mice. Tissue tropism of this isolate was not determined. The in vivo infectivity characteristics of these isolates suggests that Tc-O and Tc-A are similar and differ markedly from Tc-D.

Animals↗
PubMed1990

Histologic and immunochemical study of the pathogenesis of heartwater (Cowdria ruminantium infection) in goats and mice.

Eleven adult goats and 32 adult outbred mice were inoculated IV with Cowdria ruminantium-infected blood (Kwanyanga isolate), monitored clinically, then serially euthanatized. Predominant clinical signs of disease in goats were depression, head tremors, seizures, and dyspnea. In mice, dyspnea and depression were the only clinical signs of disease noticed. Tissues were examined histologically and immunohistochemically for C ruminantium colonies or antigen. In goats, C ruminantium was detected only in endothelial cells of the brain, even though gross and microscopic lesions were confined to the thorax. In mice, C ruminantium was detected only in endothelial cells of the heart and lungs.

Animals↗
PubMed1989

Intravenous endotoxin recruits a distinct subset of human neutrophils, defined by monoclonal antibody 31D8, from bone marrow to the peripheral circulation.

Human neutrophils label with fluorochrome-labeled monoclonal antibody 31D8 as bright or dull. We determined the source and fate of 31D8 dull neutrophils by studying volunteers injected with endotoxin, epinephrine, or hydrocortisone, by examining bone marrow, and by examining skin blister exudate. We find that 31D8 dull neutrophils are normally not present in significant numbers in the circulation, are present in large numbers in normal marrow, and are recruited from the marrow by endotoxin, to a lesser extent by steroid, but not at all by epinephrine. 31D8 dull pattern correlates with morphologic immaturity in postendotoxin peripheral blood and bone marrow; however, blister exudate neutrophils contain only morphologically mature neutrophils, of which a significant number are 31D8 dull. We conclude that 31D8 dull neutrophils reside primarily in bone marrow and are released by agents which enhance bone marrow release of neutrophils. Their accumulation in skin blister exudate is unexplained, but suggests a special role in the inflammatory process.

Adult↗
PubMed1989

Delayed phalaris grass toxicosis in sheep and cattle.

A phalaris grass (Phalaris caroliniana) caused neurologic signs and lesions in cattle and sheep. The sheep were hyperexcitable and uncoordinated, with severe muscle twitching, stiff gait, and head nodding. The cattle were thin, nervous, and ataxic. One feature of chronic phalaris toxicosis in these cases was onset of signs weeks or months after removal of the animals from the forage.

Animals↗
PubMed1989

Contribution of socioeconomic status to black/white differences in cancer incidence.

Blacks and Whites have very different cancer incidence rates for many sites, but this may largely be due to the racial differences in socioeconomic status (SES). The authors tested this hypothesis by determining the effect of adjustment for SES on the black/white incidence ratios for 12 cancer sites. Race-specific census tract-level SES variables (median family income, percent below poverty level, and years of education) were obtained from the 1980 US census and applied to approximately 20,000 black and 88,000 white cancer cases from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program for the years 1978 to 1982. For each cancer site (with each sex considered separately), Poisson regression was used to produce age-adjusted black/white incidence ratios, with and without adjustment for SES. The SES variable with the strongest adjusting power was percent below poverty level. For many sites (breast, in situ and invasive cervix, esophagus, male lung, pancreas, stomach) poverty accounted for much or all of the racial differences. For several sites (bladder, multiple myeloma, prostate, uterine corpus), large racial differences persisted after adjustment for poverty, and these findings suggest directions for investigating the etiology of these cancers.

Adult↗
PubMed1989

Intramedullary bone repair and ingrowth into porous coated implants in the adult chicken: a histologic study and biochemical analysis of collagens.

A new model was developed to study the histologic and biochemical events during intramedullary bone repair and ingrowth into porous coated implants. Adult chickens were used because of the availability of specific antibody probes. Repair in the metaphysis and diaphysis were compared. Entering through a medial arthrotomy, the distal tibiotarsus was reamed and either implanted with a double-ended porous coated rod or allowed to heal without implantation of a rod. Specimens analyzed histologically at 7, 14, 21, and 70 days postoperatively revealed direct formation of bone by osteoblasts with no evidence of a cartilaginous phase. At 70 days bony ingrowth was observed deep within the porous surface. Analysis of collagens with sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the synthesis of type I collagen predominated. Biosynthetic data coupled with quantitative immunologic analyses using antibodies to type II and type X collagen showed that neither of these two collagen types, which are characteristic of cartilage undergoing endochondral ossification, were produced during intramedullary bone repair. These results establish that the adult chicken is capable of bony ingrowth into porous coated implants and that this process is through direct bone deposition by osteoblasts without a cartilaginous intermediate.

Animals↗
PubMed1989

Protection of goats against Caribbean and African heartwater isolates by the Ball 3 heartwater vaccine.

Two groups of castrated male adult goats (three goats/group) were infected intravenously with the Ball 3 vaccine strain of Cowdria ruminantium and treated with long-acting oxytetracycline at the onset of clinical disease 10 days later. Five weeks post-vaccination one group was challenged with a Caribbean isolate (Gardel) and the other group with a West African isolate (Mali) of C. ruminantium. Non-vaccinated controls infected with either the Gardel or Mali isolate died. All of the vaccinated animals challenged with the Gardel strain reacted and survived. The three vaccinated animals challenged with the Mali isolate also reacted and two died of heartwater.

Animals↗
PubMed1989

Cancer chemotherapy with immunostimulation: a nonhomogeneous stochastic model for drug resistance. I. One drug case.

In this paper we develop a nonhomogeneous stochastic model for drug resistance in chemotherapy that permits killing resistant cells with immunostimulation. The probability distribution of the number of resistant tumor cells, the probability of no resistant tumor cells, and the expected value and cumulants of the number of resistant tumor cells are derived under very general conditions. The application of these results is illustrated with some numerical examples.

Adjuvants, Immunologic↗