Search PubMed⌕ Search

Biomedical subjects

W White

Publications and source records attributed to W White.

97 records · Page 6Linked to original sources
PubMedDate not supplied

Reanalysis of the Harvard Six Cities Study, part I: validation and replication.

Because the results of the Harvard Six Cities Study played a critical role in the establishment of the current U.S. ambient air quality objective for fine particles (PM(2.5)), the U.S. Environmental Protection Agency, industry, and nongovernmental organizations called for an independent reanalysis of this study to validate the original findings reported by Dockery and colleagues in the New England Journal of Medicine (vol. 329, pp. 1753-1759) in 1993. Validation of the original findings was accomplished by a detailed statistical audit and replication of original results. With the exception of occupational exposure to dust (14 discrepancies of 249 questionnaires located for evaluation) and fumes (15/249), date of death (2/250), and cause of death (2/250), the audit identified no discrepancies between the original questionnaires and death certificates in the audit sample and the analytic file used by the original investigators. The data quality audit identified a computer programming problem that had resulted in early censorship in 5 of the 6 cities, which resulted in the loss of approximately 1% of the reported person-years of follow-up; the reanalysis team updated the Six Cities cohort to include the missing person-years of observation, resulting in the addition of 928 person-years of observation and 14 deaths. The reanalysis team was able to reproduce virtually all of the original numerical results, including the 26% increase in all-cause mortality in the most polluted city (Stubenville, OH) as compared to the least polluted city (Portage, WI). The audit and validation of the Harvard Six Cities Study conducted by the reanalysis team generally confirmed the quality of the data and the numerical results reported by the original investigators. The discrepancies noted during the audit were not of epidemiologic importance, and did not substantively alter the original risk estimates associated with particulate air pollution, nor the main conclusions reached by the original investigators.

Air Pollutants↗
PubMedDate not supplied

Reanalysis of the Harvard Six Cities Study, part II: sensitivity analysis.

Following the validation and replication of the Harvard Six Cities Study (Krewski et al., this issue), we conducted a wide range of sensitivity analyses to explore the observed associations between long-term exposure to fine particle or sulfate air pollution and mortality. We examined the impact of alternative risk models on estimates of risk, taking into account covariates not included in the original analyses. These risk models provided a basis for identifying covariates that may confound or modify the association between fine particle or sulfate air pollution and mortality, and for identifying sensitive population subgroups. The possibility of confounding due to occupational exposures was also investigated. Residence histories were coded for the study subjects and were used to examine temporal patterns of exposure and risk. Our sensitivity analyses showed the mortality risk estimates for fine particle and sulfate air pollution to be highly robust against alternative risk models of the Cox proportional hazards family, including models with additional covariates from the original questionnaires not included in the original published analyses. There was limited evidence of departures from the proportional hazards assumption. Flexible exposure-response models provided some evidence of departures from linearity at both low and high sulfate concentrations. Incorporating information on changes over time in cigarette smoking and body mass index had little effect on the association between fine particles and mortality. There was limited evidence of variation in risk with attained age, gender, smoking status, occupational exposure to dust and fumes, marital status, heart or lung diseases, or lung function. However, air pollution risk did appear to decreasing with increasing educational attainment. Extensive adjustment for occupation using aggregate indices of occupational "dirtiness" and occupational exposure to known lung carcinogens had little impact on the mortality risks associated with particulate air pollution. Our evaluation of population mobility indicated that relatively few subjects moved from their original city of residence. Attempts to identify critical exposure time windows were limited by the lack of marked interindividual variation in temporal exposure patterns throughout the study period. Overall, this extensive sensitivity analysis both supported the conclusions reached by the original investigators and demonstrated the robustness of these conclusions to alternative analytic approaches.

Age Factors↗
PubMedDate not supplied

Computed tomography of benign cystic teratoma of the omentum.

Benign cystic teratoma of the omentum is a rare gynecologic condition. No cases have been diagnosed preoperatively; six cases have been reported in association with an ovarian teratoma. We report a seventh case in which ultrasound and CT were used preoperatively.

Dermoid Cyst↗
PubMedDate not supplied

Juvenile xanthogranuloma of the paravertebral soft tissue in infancy: a report of two cases.

We report 2 cases of paravertebral soft tissue lesions with the histologic features of juvenile xanthogranuloma, both of which occurred in infants. Juvenile xanthogranuloma situated in the soft tissue is rare. We describe 2 cases with similar clinical and pathologic features; there has been no recurrence at 1 and 2 years after excision, respectively.

Adipose Tissue↗
PubMedDate not supplied

Porcine collagen corneal shield treatment of persistent epithelial defects following penetrating keratoplasty.

Treatment of persistent epithelial defects following penetrating keratoplasty (PK) can be difficult. The use of a 24-hour porcine collagen corneal shield (Bausch & Lomb) to promote epithelialization of these cases was compared to the use of the hydrophilic bandage soft contact lens (Bausch & Lomb, plano O4). Twenty-three consecutive patients treated for persistent epithelial defect following PK were reviewed. Sixteen of 22 (73%) treated with a bandage soft contact lens healed completely. None of seven patients with persistent epithelial defect treated with collagen shield therapy healed. Six of these seven patients were subsequently treated with a bandage soft contact lens; five (83%) healed with this therapy. These data suggest that the 24 hour collagen corneal shield is not useful in treating persistent epithelial defect following PK and that a bandage soft contact lens is significantly more effective (P less than 0.01) in these cases.

Adult↗
PubMedDate not supplied

Expression of interleukin-10 in human gestational tissues.

OBJECTIVE: To determine production of interleukin-10 (IL-10) by interleukin-1 beta (IL-1 beta) in cultured decidual, chorion, and amnion cells and whether IL-10 is produced in gestational tissues under the setting of infection-associated preterm labor. METHODS: Decidual, chorion, and amnion cells were isolated from term placentas and grown in primary culture. The cells were incubated with various concentrations of IL-1 beta and then culture supernatants were assayed for IL-10 by enzyme-linked immunosorbent assay. In subsequent studies, gestational membranes were isolated from a normal-term pregnancy and a preterm pregnancy complicated by chorioamnionitis. Tissues were evaluated for IL-10 expression by immunohistology and in situ hybridization. Human gestational tissues were collected from 38 women experiencing: 1) term cesarean delivery without labor; 2) normal-term vaginal delivery; 3) preterm cesarean delivery without labor; 4) preterm vaginal delivery without chorioamnionitis; and 5) preterm vaginal delivery with concomitant chorioamnionitis. Amnion, chorion, and decidua were isolated, total RNA from each tissue was extracted, and the presence of IL-10 mRNA was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Decidual cells in culture produced IL-10 in response to IL-1 beta, but chorion and amnion cells produced no IL-10 protein. In vivo protein expression by immunohistology showed that most protein was detected within decidua while cells within amnion and chorion rarely had detectable IL-10 protein. In vivo RT-PCR samples demonstrated the strongest IL-10 mRNA signal from decidua samples, although IL-10 mRNA was also noted in chorion and amnion of placentas obtained after preterm labor. CONCLUSION: Maternal decidual cells can potentially produce IL-10, but fetal membranes (amnion and chorion) appear to have limited capabilities to produce IL-10. The relative inability of fetal tissues to produce IL-10 may play an important role in the pathophysiology of infection-associated preterm labor.

Amnion↗