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Biomedical subjects

Charles Poole

Publications and source records attributed to Charles Poole.

15 recordsLinked to original sources
PubMed2003

Accuracy of fetal growth indicators as surrogate measures of steroid hormone levels during pregnancy.

This study evaluates the use of fetal growth characteristics as surrogate measures for steroid hormone exposures during pregnancy. The validity of using birth weight, birth length, ponderal index, and placental weight as indicators of pregnancy hormone exposures was assessed using third-trimester serum samples from 568 pregnant women who participated in the Child Health and Development Studies, Berkeley, California (1959-1966). The magnitude of the associations between birth characteristics and hormone concentrations was assessed using geometric means, Pearson's correlations, and linear and logistic regression. Accuracy was evaluated using sensitivity, specificity, and receiver operating characteristic curve analyses. The strongest and most consistent association observed was between birth weight and estriol levels. Despite a positive correlation (r = 0.32) and strong associations with high estriol levels (odds ratio for highest compared with lowest birth weight quartile = 6.63, 95% confidence interval: 3.20, 12.5), the predictive performance of birth weight as a proxy for estriol levels was poor (area under the receiver operating characteristic curve = 0.66, 95% confidence interval: 0.61, 0.71). Likewise, all fetal growth measures revealed little discriminatory ability as indicators of estriol, estrone, estradiol, or progesterone levels. Thus, observed associations with these surrogate measures may not be a reflection of pregnancy hormone exposure and should be interpreted with caution.

Biomarkers↗
PubMed2003

Childhood leukemia: electric and magnetic fields as possible risk factors.

Numerous epidemiologic studies have reported associations between measures of power-line electric or magnetic fields (EMFs) and childhood leukemia. The basis for such associations remains unexplained. In children, acute lymphoblastic leukemia represents approximately three-quarters of all U.S. leukemia types. Some risk factors for childhood leukemia have been established, and others are suspected. Pathogenesis, as investigated in animal models, is consistent with the multistep model of acute leukemia development. Studies of carcinogenicity in animals, however, are overwhelmingly negative and do not support the hypothesis that EMF exposure is a significant risk factor for hematopoietic neoplasia. We may fail to observe effects from EMFs because, from a mechanistic perspective, the effects of EMFs on biology are very weak. Cells and organs function despite many sources of chemical "noise" (e.g., stochastic, temperature, concentration, mechanical, and electrical noise), which exceed the induced EMF "signal" by a large factor. However, the inability to detect EMF effects in bioassay systems may be caused by the choice made for "EMF exposure." "Contact currents" or "contact voltages" have been proposed as a novel exposure metric, because their magnitude is related to measured power-line magnetic fields. A contact current occurs when a person touches two conductive surfaces at different voltages. Modeled analyses support contact currents as a plausible metric because of correlations with residential magnetic fields and opportunity for exposure. The possible role of contact currents as an explanatory variable in the reported associations between EMFs and childhood leukemia will need to be clarified by further measurements, biophysical analyses, bioassay studies, and epidemiology.

Animals↗
PubMed2003

Neonatal candidemia and end-organ damage: a critical appraisal of the literature using meta-analytic techniques.

OBJECTIVE: Neonatal candidemia is an increasing cause of infant morbidity and mortality. We evaluated the current medical literature in an effort to critique the literature and to document the reported prevalences of end-organ damage after neonatal candidemia. METHODS: We analyzed all peer-reviewed articles of neonatal candidemia published in the English language; inclusion criteria included a cohort limited to all neonatal intensive care unit admissions or all episodes of candidemia in neonates. Articles that also incorporated older patients, did not define a numerator and a denominator for at least 1 form of end-organ damage, included patients from other reports, or did not include all episodes of candidemia in the source population were excluded from the analysis. RESULTS: Thirty-four articles reported episodes of candidemia and mortality; 21 articles reported prevalence for at least 1 form of end-organ damage. Only 4 (19%) of 21 articles reported prevalence for >4 forms of end-organ damage from the following list: endophthalmitis, meningitis, brain parenchyma invasion, endocarditis, renal abscesses, positive cultures from other normally sterile body fluids, or hepatosplenic abscesses. The median reported prevalence of endophthalmitis was 3% (interquartile range [IQR]: 0%-17%), of meningitis was 15% (IQR: 3%-23%), of brain abscess or ventriculitis was 4% (IQR: 3%-21%), of endocarditis was 5% (IQR: 0%-13%), of positive renal ultrasound was 5% (IQR: 0%-14%), and of positive urine culture was 61% (IQR: 40%-76%). The medical literature concerning end-organ evaluation after episodes of neonatal candidemia is heterogeneous and consists largely of single-center retrospective studies. Year that the data were collected and prevalence of neonates infected with Candida albicans were associated with observed heterogeneity. CONCLUSIONS: Given the heterogeneity of the medical literature, precise estimates of the frequencies of end-organ damage are not possible and a prospective multicenter trial is warranted, but the data from the published literature suggest that the prevalence of neonates with end-organ damage not only is greater than 0 but also is high enough that until such a prospective trial is completed, end-organ studies should be considered before the conclusion of antifungal therapy.

Candida albicans↗
PubMed2003

Is family history of breast cancer a marker of susceptibility to exposures in the incidence of de novo adult acute leukemia?

The risk factors for adult acute leukemia incidence have been difficult to establish. Family history of cancer might interact with environmental exposures to produce associations that are otherwise difficult to detect. In addition to family history of leukemia or other hematopoietic cancers, family history of breast cancer could be a marker of susceptibility, because leukemia and breast cancer are known to cluster in families that have specific germ-line mutations. In a population-based case control study of 779 incident adult acute leukemia patients and 625 controls, we estimated the relative risk for exposed individuals with a family history compared with unexposed individuals without a family history (RR(11)), along with a measure of interdependence, the interaction contrast ratio. Combined with a family history of breast cancer, ever-smoking [RR(11) = 2.4, 95% confidence interval (CI): 1.2-4.8], general solvent exposure (RR(11) = 1.9, 95% CI: 1.1-3.4), aromatic hydrocarbon exposure (RR(11) = 3.8, 95% CI: 1.1-14), and diagnostic ionizing radiation exposure (RR(11) = 2.1, 95% CI: 1.2-3.8) were all associated with increased incidence. Furthermore, there was no increased incidence associated with any of these exposures in the absence of a family history of breast cancer and no increased incidence for family history of breast cancer in the absence of exposures. The pattern of relative risks strongly suggested synergy across exposures. Family history of breast cancer might be a marker of susceptibility to a range of leukemia risk factors, whose effects are generally weak or nonexistent when considered alone.

Adolescent↗
PubMed2002

Family history of cancer and incidence of acute leukemia in adults.

Family history of cancer may represent shared genetic and environmental risk factors for leukemia. The authors examined associations of first-degree family history of cancer with adult acute leukemia incidence by using data on 811 patients (or their proxies) identified at diagnosis and 637 population-based controls in the United States and Canada during 1986-1990. For proxy-interviewed patients, relative risks were elevated for family history of any cancer (relative risk = 1.7, 95% confidence interval (CI): 1.3, 2.4), hematopoietic cancer (relative risk = 1.8, 95% CI: 1.1, 3.0), leukemia (relative risk = 2.4, 95% CI: 1.3, 4.6), and breast cancer (relative risk = 1.7, 95% CI: 1.0, 3.0) but not for colorectal, prostate, or lung cancer. For self-interviewed patients, family history of hematopoietic cancer was inversely associated with leukemia incidence (relative risk = 0.6, 95% CI: 0.4, 1.1). Regardless of patient interview type, history of breast cancer in sisters was positively associated with adult acute leukemia, whereas history of breast cancer in mothers was not. The role of family history of cancer in leukemia etiology is unclear because of differential reporting by patients and proxies. Specifically, self-interviewed patients may underreport cancer in their first-degree relatives. Associations between family history of breast cancer and leukemia incidence may be the result of unmeasured, shared etiologies specific to these cancers.

Adult↗
PubMed2002

Gender difference in HIV RNA levels: a meta-analysis of published studies.

Plasma HIV RNA copy number is a strong prognostic marker of progression to AIDS in antiretroviral-naive persons. Recent research suggests women have lower HIV RNA levels than comparable men. Because clinical care recommendations currently include HIV RNA thresholds as a guide to initiating antiretroviral therapy (ART), the authors undertook the present quantitative meta-analysis to explore the relation between gender and plasma HIV RNA levels. A gender difference in HIV RNA levels was observed in the CD4-unadjusted and -adjusted analyses. The summary estimate including only CD4-adjusted results with the lowest heterogeneity indicated that on average, women have 41% lower plasma HIV RNA levels than men (-.23 log; 95% confidence interval [CI], -.16 to -.31 log ). Because numerous studies have found similar HIV disease progression rates in men and women, adjusted for CD4 but not HIV RNA, the present meta-analysis supports the use of lower HIV RNA thresholds in women than in men to guide initiation of ART. Given the patient characteristics in the original studies used in this meta-analysis, the results are most likely to apply to therapy-naive persons with CD4 lymphocyte counts >200 cells/mm, a subgroup for whom HIV RNA levels may strongly influence the decision to initiate therapy.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Neighborhood characteristics associated with the location of food stores and food service places.

BACKGROUND: Although the relationship between diet and disease is well established, sustainable dietary changes that would affect risk for disease have been difficult to achieve. Whereas individual factors are traditional explanations for the inability of some people to change dietary habits, little research has investigated how the physical availability of healthy foods affects individuals' diets. This study examines the distribution of food stores and food service places by neighborhood wealth and racial segregation. METHODS: Names and addresses of places to buy food in Mississippi, North Carolina, Maryland, and Minnesota were obtained from respective departments of health and agriculture. Addresses were geocoded to census tracts. Median house values were used to estimate neighborhood wealth, while the proportion of black residents was used to measure neighborhood racial segregation. RESULTS: Compared to the poorest neighborhoods, large numbers of supermarkets and gas stations with convenience stores are located in wealthier neighborhoods. There are 3 times fewer places to consume alcoholic beverages in the wealthiest compared to the poorest neighborhoods (prevalence ratio [PR]=0.3, 95% confidence interval [CI]=0.1-0.6). Regarding neighborhood segregation, there are 4 times more supermarkets located in white neighborhoods compared to black neighborhoods (PR=4.3, 95% CI=1.5-12.5). CONCLUSIONS: Without access to supermarkets, which offer a wide variety of foods at lower prices, poor and minority communities may not have equal access to the variety of healthy food choices available to nonminority and wealthy communities.

Black or African American↗
PubMed2002

Assessing exposure in epidemiologic studies to disinfection by-products in drinking water: report from an international workshop.

The inability to accurately assess exposure has been one of the major shortcomings of epidemiologic studies of disinfection by-products (DBPs) in drinking water. A number of contributing factors include a) limited information on the identity, occurrence, toxicity, and pharmacokinetics of the many DBPs that can be formed from chlorine, chloramine, ozone, and chlorine dioxide disinfection; b) the complex chemical interrelationships between DBPs and other parameters within a municipal water distribution system; and c) difficulties obtaining accurate and reliable information on personal activity and water consumption patterns. In May 2000, an international workshop was held to bring together various disciplines to develop better approaches for measuring DBP exposure for epidemiologic studies. The workshop reached consensus about the clear need to involve relevant disciplines (e.g., chemists, engineers, toxicologists, biostatisticians and epidemiologists) as partners in developing epidemiologic studies of DBPs in drinking water. The workshop concluded that greater collaboration of epidemiologists with water utilities and regulators should be encouraged in order to make regulatory monitoring data more useful for epidemiologic studies. Similarly, exposure classification categories in epidemiologic studies should be chosen to make results useful for regulatory or policy decision making.

Acetates↗
PubMed2002

Steroid hormone levels during pregnancy and incidence of maternal breast cancer.

Previous studies evaluating pregnancy hormone levels and maternal breast cancer were limited to surrogate indicators of exposure. This study directly evaluates the association between measured serum steroid hormone levels during pregnancy and maternal risk of breast cancer. A nested case-control study was conducted to examine third-trimester serum levels of total unconjugated estradiol, estrone, estriol, and progesterone in women who were pregnant between 1959 and 1966. Cases (n = 194) were diagnosed with in situ or invasive breast cancer between 1969 and 1991. Controls (n = 374) were matched to cases by age at the time of index pregnancy, using randomized recruitment. Elevated progesterone levels were associated with a decreased incidence of breast cancer [odds ratio (OR) for progesterone > or =270 ng/ml, 0.49; 95% confidence interval (CI), 0.22-1.1] relative to those below the lowest decile. This association was stronger for cancers diagnosed at or before age 50 (OR for progesterone > or =270 ng/ml, 0.3; 95% CI, 0.1-0.9). Increased estrone levels were associated with an increased incidence overall (OR for estrone > or =18.7 ng/ml, 2.5; 95% CI, 1.0-6.2), whereas a positive association with estradiol was not observed. Too few cases occurred within 15 years of the index pregnancy to compare adequately the short- and long-term effects of pregnancy hormone exposure. When estrogen-to-progesterone ratios were evaluated, there was an indication of a modest increased incidence of breast cancer for those with high total estrogens and high estrone levels relative to progesterone. These findings suggest that pregnancy steroid hormone levels are risk factors for breast cancer.

Adolescent↗
PubMed2002

The darkness at the end of the tunnel: summary and evaluation of an international symposium on light, endocrine systems and cancer.

Research on light at night and cancer is evolving at an accelerating pace, fueled largely by exciting results in rodent toxicology and basic human biology. Epidemiologic research is at a relatively early stage of development in which the exposure surrogates such as shift work and blindness predominate. Causal graphs for shift work, light at night and breast cancer illustrate some of the subtleties that can arise in the use of exposure surrogates of different kinds. Baseline data on circadian rhythms and melatonin cycles among human populations living at different latitudes are needed. Epidemiologic study of this topic is expected to mature soon as studies begin to incorporate quantitative and semiquantitative measurements and personal histories of exposure to light at night. The current emphasis on breast cancer should widen to include other cancers and intermediate outcomes. An advance in epidemiologic studies of blind persons would be to compare cancer rates between the "cortically blind" and the "retinally blind" within levels of visual impairment. Without a proposed intervention to reduce exposure to light at night, attributable fraction and attributable caseload estimates are meaningless. In the near future, both epidemiologic and laboratory research in this area are expected to grow appreciably in scope and scale.

Darkness↗
PubMedDate not supplied

Preventable drug-related hospital admissions.

OBJECTIVE: To estimate the prevalence of preventable drug-related hospital admissions (PDRAs) and to explore if selected study characteristics affect prevalence estimates. METHODS: Keyword search of MEDLINE (1966-December 1999), International Pharmaceutical Abstracts (1970-December 1999), and hand search. Two reviewers independently selected studies published in peer-reviewed journals and extracted crude prevalence estimates and study characteristics. Trials had to specifically address consequences of drug therapy requiring hospital admission and include a quantitative preventability assessment. Stratified analysis and meta-regression were used to explore the association between study characteristics and prevalence estimates. DATA SYNTHESIS: Fifteen studies reported a median PDRA prevalence of 4.3% (interquartile range [IQR] 3.1-9.5%). The median preventability rate of drug-related admissions was 59% (IQR 50-73%). No evidence of publication bias related to study size could be determined. Because the individual study results were highly heterogeneous (Cochran's Q = 176, df = 14; p < 0.001), no meta-analytic summary estimate was computed. Stratified analysis suggested an association between prevalence estimates and 3 study characteristics: exclusion of first admissions (readmission studies: average PDRA prevalence of 14.0 %, estimated prevalence OR = 3.7); mean age of admissions >70 (OR = 2.1); and inclusion of "indirect" drug-related morbidity, such as omission errors or therapeutic failure (OR = 1.9). There was little evidence of other associations with prevalence estimates, such as selection of specific hospital units, exclusion/inclusion of planned admissions, country, and specified methods of PDRA case ascertainment. CONCLUSIONS: Drug-related morbidity is a significant healthcare problem, and a great proportion is preventable. Study methods in prevalence reports vary and should be considered when interpreting findings or planning future research.

Drug-Related Side Effects and Adverse Reactions↗