Search PubMed⌕ Search

Biomedical subjects

W Black

Publications and source records attributed to W Black.

At least 19 recordsLinked to original sources
PubMed2006

A comparison of national estimates of obesity prevalence from the behavioral risk factor surveillance system and the National Health and Nutrition Examination Survey.

BACKGROUND: Obesity interventions are implemented at state or sub-state level in the United States (US), where only self-reported weight and height data for adults are available from the Behavioral Risk Factor Surveillance System (BRFSS). The prevalence estimates of overweight and obesity generated from self-reported weight and height from BRFSS are known to underestimate the true prevalence. However, whether this underestimation is consistent across different demographic groups has not been fully investigated. METHODS: In this study, we compared the prevalence estimates of obesity (body mass index (BMI) > or =30 kg/m(2)) and overweight (BMI > or =25 kg/m(2)) in different demographic groups in the US from the National Health and Nutrition Examination Survey (NHANES) and BRFSS during 1999-2000. We also compared the rank orders of the obesity and overweight prevalence across different demographic groups from the two data sources. RESULTS: Compared to NHANES, BRFSS underestimated the overall prevalence of obesity and overweight by 9.5 and 5.7 percentage points, respectively. The underestimation differed across different demographic groups: the underestimation of obesity and overweight prevalence was higher among women (13.1 and 12.2 percentage points, respectively) than among men (5.8 and -0.6 percentage points, respectively). The variation of underestimation was higher among men. A clear inverse association between educational attainment and obesity prevalence among non-Hispanic African American women was observed from BRFSS data. However, no such association was found from NHANES. While BRFSS can identify correctly the population with the highest obesity and overweight burden, it did not accurately rank the obesity and overweight prevalence across different demographic groups. CONCLUSION: Compared to NHANES, BRFSS disproportionately underestimates the prevalence of obesity and overweight across different gender, race, age, and education subgroups.

Adult↗
PubMed2005

Differential expression of CYP1A, 2B, and 3A genes in the F344 rat following exposure to a polybrominated diphenyl ether mixture or individual components.

Polybrominated diphenyl ethers (PBDEs), used as flame retardants, have been detected in the environment and in mammalian tissues and fluids. Evidence indicates that PBDE mixtures induce CYPs through aryl hydrocarbon receptor (AhR)-dependent and -independent pathways. The present work has investigated the effects of individual components of a commercial PBDE mixture (DE71) on expression of CYP1A1, a biomarker for activation of the AhR (dioxin-like), and CYP2B and CYP3A, biomarkers for activation of the constitutive androstane and pregnanexreceptors (CAR and PXR), respectively, in the rat. Male F344 rats were dosed orally on three consecutive days with either DE71, PBDE components, 2,2',4,4'-tetraBDE (BDE47), 2,2',4,4',5-pentaBDE (BDE99), 2,2',4,4',5,5'-hexaBDE (BDE153), representative polybrominated dibenzofurans (PBDFs) present in DE71, or reference PCBs. Differential expression of target genes was determined in liver 24 h after the last dose. Quantitative PCR analysis indicated up-regulation of CYP1A1 by DE71; however, the response was weak compared to that for dioxin-like PCB126. Individual PBDE components of DE71 up-regulated CYP1A1 only at the highest administered dose (100 micromol/kg/day). Representative PBDFs efficiently up-regulated CYP1A1; therefore, they, along with other PBDFs and polybrominated dibenzodioxins detected in DE71 and individual PBDE components, may be responsible for most, if not all, dioxin-like properties previously observed for PBDEs. Conversely, PBDEs appear capable of up-regulating CYP2B and CYP3A in rats at doses similar to that for non-dioxin-like PCB153. These results indicate that in vivo PBDE-mediated toxicity would be better categorized by AhR-independent mechanisms, rather than the well-characterized AhR-dependent mechanism associated with exposure to dioxin-like chemicals.

Administration, Oral↗
PubMed2003

Social deprivation and the public health risks of community drinking water supplies in New Zealand.

STUDY OBJECTIVE: Quantitative evidence linking environmental exposures and social status at sub-national scales is surprisingly limited. This study investigated the public health risks associated with community water supplies in relation to social status in New Zealand. DESIGN: An ecological study using a Geographic Information System (GIS) to compare the grade of community water supplies with an index of social deprivation for small areas. SETTING: New Zealand. PARTICIPANTS: The New Zealand population usually resident in meshblocks (census areas) with a community water supply (70% of the 1996 population of 3.6 million people). MAIN RESULTS: People living in deprived areas are exposed to greater public health risks from community water supplies. In urban areas, the odds of water supplies being high risk were 3.76 times greater for the most deprived decile compared with the least deprived decile (95% CI: 2.95 to 4.78). CONCLUSIONS: It is probable that deprived communities in New Zealand are experiencing a disproportionate burden of adverse health effects as a result of poor water quality.

Adolescent↗
PubMed2001

Determinants of melanoma in a case-control study of twins (United States).

OBJECTIVES: To estimate the relative contribution of environmental and genetic factors disposing towards the development of melanoma. METHODS: We investigated risk factors for melanoma in a case-control study conducted among 185 North American twin pairs in which one was diagnosed with melanoma and the other (the co-twin of the case) was not. We considered monozygous (MZ) and dyzygous (DZ) twins separately. RESULTS: While greater risk of melanoma was associated with number of large nevi in DZ twins (adjusted OR = 26.6 (4.2-170.8) for three or more large moles), this was not the case for MZ twins (adjusted OR = 1.4 (0.6-3.2) for three or more large moles). Elevated risks of developing melanoma with site-specific sun exposures resulting in sunburn also appeared to be confined to DZ twins. Despite the number of identical twins reporting a difference in mole prevalence, we observed only a modest and inconsistent increase in melanoma risk attributable to that factor, whereas the increase within fraternal twin pairs was larger by an order of magnitude. CONCLUSIONS: If confirmed, this indicates that the significance of mole prevalence as a risk factor for melanoma is largely as a genetic, rather than an environmental, factor. We noticed an increased risk of developing melanoma among DZ twins who drank moderate amounts of beer, but we believe this result may be due to the sun-exposure activities of those people most likely to drink moderate amounts of beer.

Adolescent↗
PubMed1999

The significance of the persistent presence of acid-fast bacilli in sputum smears in pulmonary tuberculosis.

STUDY OBJECTIVES: Identification of acid-fast bacilli (AFB) in the sputum smear at the completion of tuberculosis therapy is in some settings considered evidence of treatment failure. However, some patients with pulmonary tuberculosis (TB) will have positive smear results with negative sputum culture results at the end of therapy. The objectives of this study were to estimate the prevalence of persisting positive sputum smear results in patients with TB and to identify characteristics that distinguish patients with persistently positive sputum smear results who also had negative sputum culture results from patients identified as treatment failures. DESIGN: A population-based, historical cohort study with nested case control study. SETTING: British Columbia Division of Tuberculosis Control central case registry. PATIENTS: All 428 patients with culture-proven pulmonary TB in British Columbia over 7 years with sputum that was positive for AFB. METHODS: Review of laboratory data of all 428 patients, as well as clinical data of a subset of 30 patients with persistently positive smear results beyond 20 weeks. RESULTS: Sputum smears were positive for AFB in 205 patients (48%) at 4 weeks, in 30 patients (7%) at 20 weeks, and in 12 patients (3%) at 36 weeks. Of the patients with smear results that were persistently positive at 20 weeks, 23 (77%) had negative sputum culture results and 7 (23%) had positive sputum culture results (ie, they were treatment failures). Patients identified as treatment failures had more localized disease as shown on chest radiographs, had less radiographic improvement at follow-up, had a higher prevalence of drug resistance, and were less compliant with medications than patients with persistently positive smear results and negative culture results. No subject with a negative culture result relapsed over the 6- to 48-month observation period. CONCLUSION: Sputum that is persistently positive for AFB in patients in developed countries is more likely to be associated with negative culture results than with treatment failure.

Adult↗
PubMed1996

Endodermal sinus tumor and embryonal carcinoma of the ovary in a 53-year-old woman.

BACKGROUND: Germ cell tumors, the most common ovarian malignancies in females under the age of 21, are rare in older women. We report an unusual case of a mixed embryonal carcinoma and endodermal sinus germ cell tumor in a perimenopausal patient and review the differential diagnosis and management of these malignancies with respect to age. CASE: A 53-year-old woman complaining of irregular menses and pelvic pain was found to have a large pelvic mass and a positive pregnancy test. Subsequent investigation revealed a large left adnexal mass, and an elevated beta-HCG and alpha-AFP. At laparotomy, a mixed germ cell tumor was found. The patient was treated with multiagent chemotherapy and currently is without evidence of disease. CONCLUSION: Although rare, the diagnosis of germ cell tumor should be considered in older women presenting with a large pelvic mass. The treatment and prognosis is similar regardless of age, except that reproductive-sparing surgery is not a priority in the older patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Quinolone arthropathy in immature rabbits treated with the fluoroquinolone, PD 117596.

To study the potential of the fluorquinolone, PD 117596 to cause arthropathy in experimental animals, immature rabbits were orally administered the drug for five days at 0, 100, 350, 500 and 750 mg/kg. Characterization of changes induced in major synovial joints was based on: macroscopic and histopathologic observations, transmission electron microscopic examinations and magnetic resonance imaging. Preferentially targeting the knee, PD 117596 produced vesicles and erosions in articular cartilage which resembled, morphologically, those described in other laboratory species. Lesion incidence was not clearly dose-related. In the perivesicular region, degenerate chondrocytes were intermixed with hypertrophic cartilage cells and chondrocyte clusters. Ultrastructurally, hypertrophic chondrocytes were the consequence of karyomegaly and RER proliferation. Matrix density was reduced due to collagen and proteoglycan loss. Joint structures were readily visualized by magnetic resonance imaging which identified thickened articular cartilage, surface irregularities consistent with ruptured vesicles and separation of opposing articular surfaces secondary to synovival effusions. The immature rabbit, although less sensitive than the juvenile dog to the arthropathic effects of quinolones, was nonetheless a good model to study this experimental osteoarticular disease.

Animals↗
PubMed1996

Pattern of utilization of rifabutin for prophylaxis of Mycobacterium avium complex among patients with advanced human immunodeficiency virus disease in a community setting.

OBJECTIVE: To characterize the pattern of utilization, effectiveness, and safety profile of rifabutin for Mycobacterium avium complex (MAC) prophylaxis among individuals with advanced human immunodeficiency virus disease in a community setting. METHODS: Individuals who, while registered in the provincial drug distribution program, had at least one CD4 count below 100 cells/mm3 for the period 1 May 1993 to 31 March 1994 were included. MAC diagnoses were identified through a record linkage with the mycobacterial reference laboratory of the Provincial Centre for Disease Control. In order to determine the occurrence of adverse events, a survey was sent in March 1994 to the 98 primary care physicians prescribing rifabutin prophylaxis in the province. We achieved 100% response rate to the survey. RESULTS: During the study period 515 patients in our drug treatment program were eligible to receive MAC prophylaxis. Of these, 340 (66%) were being prescribed rifabutin as recommended by current guidelines. Rifabutin prophylaxis use was significantly associated with use of antiretroviral therapy. The product limit estimate of the cumulative incidence of MAC at 10 months was 13.0% among those receiving rifabutin prophylaxis. Diagnosis of MAC was significantly associated with a lower baseline CD4 count (cumulative incidence 7.1% and 18.1% for CD4 > or = 50 and < 50 cells/mm3, respectively, P = 0.01). A total of four cases of uveitis, eight cases of pseudo-jaundice, and five cases of arthralgia in 16 patients were identified by our survey. CONCLUSION: Our data demonstrates that rifabutin prophylaxis of MAC is being used by approximately 66% of eligible individuals. Rifabutin use was associated with antiretroviral use, which may reflect individuals' attitudes towards medications. Our intention-to-treat analysis, with a 10 month cumulative MAC incidence of 13.0% among those receiving rifabutin prophylaxis, is in keeping with break-through rates previously reported in the context of clinical trials. Our results also support previous observations that the risk of MAC infection greatly increases at CD4 counts < 50 cells/mm3. Rifabutin prophylaxis was generally well-tolerated in our program.

AIDS-Related Opportunistic Infections↗
PubMed1996

Species distribution in human immunodeficiency virus-related mycobacterial infections: implications for selection of initial treatment.

Management of mycobacterial infection is species specific; however, treatment is prompted by positive smears or cultures, often several weeks before species identification. The objective of this study was to determine the species distribution of mycobacterial isolates from various body sites in patients infected with human immunodeficiency virus (HIV). All mycobacterial isolates recovered at St. Paul's Hospital (Vancouver, British Columbia, Canada) from April 1989 to March 1993 were reviewed. Among 357 HIV-positive patients with mycobacterial infections, 64% (96) of the sputum isolates were Mycobacterium avium complex (MAC), 18% were Mycobacterium tuberculosis, and 17% were Mycobacterium kansasii. Lymph node involvement (25 patients) was due to either MAC (72%) or M. tuberculosis (24%). Two hundred ninety-eight episodes of mycobacteremia were due to MAC (98%), M. tuberculosis (1%), and M. kansasii (1%). Similarly, cultures of 84 bone marrow biopsy specimens (99%), 19 intestinal biopsy specimens (100%), and 30 stool specimens (97%) yielded predominantly MAC. These results have implications for initial therapy, particularly in areas where rapid methods for species identification are not readily available. Because of considerable geographic variation, development of guidelines for selection of initial therapy depends on regional determination of species distribution in HIV-related mycobacterial infections.

AIDS-Related Opportunistic Infections↗
PubMed1996

HIV-related tuberculosis in British Columbia: indications of a rise in prevalence and a change in risk groups.

OBJECTIVES: To identify patients with coexisting HIV infection and tuberculosis (TB) and recent trends in prevalence and factors associated with coinfection. DESIGN: Case review. PARTICIPANTS: All known patients with TB and HIV infection in British Columbia, in whom TB was diagnosed between 1990 and 1994. This group was compared with those in whom TB was diagnosed between 1984 and 1990. OUTCOME MEASURES: Patients' demographic characteristics and risk factors for HIV infection, site of TB, occurrence of drug-resistant TB, treatment and outcome. RESULTS: Forty-four patients with HIV infection and TB were identified, of whom 16% were women, whereas non of those diagnosed from 1984 to 1990 were women, and 14 (32%) were aboriginal Canadians, compared with only 3 (8%) of those diagnosed from 1984 to 1990 (p < 0.01 for both). Forty patients had identifiable risk factors for HIV infection. A smaller proportion of the recent group than of the previous group were homosexual men (excluding those for whom risk factors were not known, 17/33 men [52%] in 1990 to 1994 v. 36/39 [92%] in 1984 to 1990), and a larger proportion were intravenous drug users (22/40 [55%] in 1990 to 1994 v. 8/39 [21%] in 1984 to 1990, p < 0.01 for both). Since 1984 an increasing proportion of patients with TB diagnosed each year have also had HIV infection (linear trend p < 0.001). Drug resistance was not found in any cultures taken at the time of diagnosis; however, rifampin resistance developed 7 months after therapy was initiated in one patient. Of the 40 patients who started therapy, 24 had directly observed therapy. Nine patients died while receiving therapy, and four died without receiving any antituberculous therapy. TB was the cause of death, or a contributing factor to death, in five cases. CONCLUSIONS: Significantly more intravenous drug users, aboriginal Canadians and women are now presenting with HIV-related TB in British Columbia. All HIV-positive patients need to be evaluated for TB, and HIV infection must be considered in assessing all newly diagnosed TB cases and in screening contacts of active cases, especially if patients have risk factors for HIV infection.

AIDS-Related Opportunistic Infections↗
PubMed1995

A pharmacokinetic study of ethanol inhibition of micronuclei induction by urethane in mouse bone marrow erythrocytes.

Urethane (ethyl carbamate) is a genotoxic carcinogen in fermented products and alcoholic beverages. The genotoxicity of urethane requires metabolic activation. Metabolism of urethane is mediated by multiple pathways, and ethanol is known to inhibit the esterase hydrolysis pathway of urethane, which accounts for over 95% of urethane metabolism. This report shows that ethanol also inhibits the induction of micronuclei by urethane in mouse bone marrow erythrocytes, presumably by inhibiting the minor pathway that generates genotoxic metabolite(s). In this study, male CD-1 mice were administered urethane, ethanol, or urethane co-administered with increasing amounts of ethanol in single intraperitoneal injections. Bone marrow polychromatic erythrocytes (PCE) obtained 24 h after injection were scored for micronuclei. The dose of urethane was 1000 mg/kg, and the doses of ethanol were 0, 625, 1250, 2000, 2250, 2500, 3000 and 3500 mg/kg. The blood ethanol level at each dose was determined. Two pharmacokinetic parameters, Cmax and AUC, were estimated for each dose. The observed Cmax of ethanol at doses of 1250, 2000, 2250, 2500, 3000 and 3500 mg/kg were 1.39, 2.84, 3.15, 3.69, 4.13 and 4.76 mg/ml, with AUCs of 1.37, 4.84, 5.88, 7.28, 10.76 and 13.51 mg.h/ml, respectively. Urethane treatment alone markedly increased the micronucleus frequency from 0.1% in the vehicle control to 2.47%. This magnitude of increase was suppressed when urethane was co-administered with ethanol at ethanol doses of 2500 mg/kg and above. At 2500, 3000 and 3500 mg/kg, the micronucleus frequencies reduced from 2.47% to 0.9, 0.44 and 0.28%, respectively. This study shows that ethanol inhibits the induction of micronuclei by urethane.

Animals↗
PubMed1995

Paediatric hospital services: are we satisfying our adolescent patients?

This study evaluated the satisfaction of adolescents with general inpatient services in a paediatric hospital. The results suggest that the adolescents were generally satisfied with the services provided. However, a number of concerns were expressed about the physical characteristics of the wards, the day to day organization of the wards, and the lack of opportunity to participate in treatment planning. The results also suggest that adolescents' satisfaction with inpatient services will be improved if more attention is given to the physical surroundings in hospital wards and the level of privacy afforded to adolescent inpatients. Finally, the results draw attention to the importance adolescents place on being involved in decisions about their treatment planning. There is a great need for studies which focus on adolescents' perceptions of health services. This will help to ensure that adolescents receive services they perceive to be relevant and effective.

Adolescent↗
PubMed1994

Tuberculosis in young adults and the elderly. A prospective comparison study.

OBJECTIVES: To compare the clinical, bacteriologic, and radiologic features of pulmonary and pleural tuberculosis in young adults and the elderly and determine if any differences exist between both groups. DESIGN: Prospective recruitment of all patients diagnosed as having pulmonary and pleural tuberculosis in British Columbia, Canada. SETTING: A population-based sample from a provincial control program TB registry. PATIENTS: A total of 218 consecutive patients whose conditions were diagnosed between January 1990 and May 1991. We excluded 15 HIV-positive patients whose conditions were diagnosed during this study. INTERVENTION: Standardized data collection of symptoms, bacteriology, and review of radiology by two readers blind to the clinical and epidemiologic data. MAIN RESULTS: There were 142 young adult patients and 76 elderly patients. The young adults had a mean age of 41.2 years and the elderly group had a mean age of 75 years of age. Fever (p = 0.002) and night sweats (p = 0.02) were more common in young adults. In culture-proven disease, hemoptysis, fever, and cough were more common in young adult (p = 0.03, 0.02, and 0.01, respectively). There was no difference in the duration of symptoms between the two groups. The odds ratio for cancers other than lung cancer, 3.98 (confidence interval, 1.49, 10.65) in the elderly group was the only significant risk factor to differ between the two groups. Skin test responses to 5TU PPD were positive in 86.2 percent of young adults and 67.6 percent of elderly patients tested (p = 0.03). A total of 79.6 percent of young adults and 88.15 percent of the elderly patients (not significant) were culture positive. Comparison of radiologic findings in young adults vs elderly patients showed no significant differences apart from those with miliary TB 0.7 percent vs 6.7 percent (p = 0.04). CONCLUSIONS: In this population-based study, young adults were more likely to have hemoptysis, fever, and cough and to have a positive PPD response. Cancer was significantly associated as a risk factor in the older age group. There was no difference in bacteriologically proven disease or radiologic findings between the two groups, apart from the more common occurrence of miliary TB in the elderly.

Adult↗
PubMed1993

Report of the International Workshop on Screening for Breast Cancer.

BACKGROUND: Over the past 30 years, eight major randomized controlled trials of breast cancer screening--with mammography and/or clinical breast examination--have been conducted. Results from several trials have been updated during the past year, and initial results of three other trials have been reported. PURPOSE: The National Cancer Institute held an International Workshop on Screening for Breast Cancer in February 1993 to conduct a thorough and objective critical review of the world's most recent clinical trial data on breast cancer screening, consider the new evidence, assess the current state of knowledge, and identify issues needing further research. METHODS: Investigators representing the eight randomized controlled trials of breast cancer screening in women aged 40-74 presented published and unpublished data. Evidence relating to the effectiveness of breast cancer screening in different age groups, especially women aged 40-49, was presented. RESULTS: For women aged 40-49, randomized controlled trials consistently demonstrated no benefit from screening in the first 5-7 years after study entry. A meta-analysis of six trials found a relative risk of 1.08 (95% confidence interval = 0.85-1.39) after 7 years' follow-up. After 10-12 years of follow-up, none of four trials have found a statistically significant benefit in mortality; a combined analysis of Swedish studies showed a statistically insignificant 13% decrease in mortality at 12 years. Only one trial (Health Insurance Plan) has data beyond 12 years of follow-up, and results show a 25% decrease in mortality at 10-18 years. Statistical significance of this result is disputed, however. In women aged 50-69, all studies show mortality reductions; three of four studies show reductions of about 30% at 10-12 years after study entry. Results from two of these trials were statistically significant. Too few women over age 70 have been included in studies for adequate analysis. CONCLUSIONS: For women aged 40-49, randomized controlled trials of breast cancer screening show no benefit 5-7 years after entry. At 10-12 years, benefit is uncertain and, if present, marginal; thereafter, it is unknown. For women aged 50-69, screening reduces breast cancer mortality by about a third. Currently available data for women age 70 or older are inadequate to judge the effectiveness of screening. IMPLICATIONS: Randomized trials have provided stronger scientific evidence regarding the effectiveness of screening for breast cancer than for any other cancer. However, much still needs to be learned. Periodic gatherings of scientists in the field should speed the process.

Adult↗