摘要:

Background.Several investigators have reported an association of blood lead or bone lead with increased blood pressure and hypertension, but questions remain concerning whether these effects are acute or chronic in nature.Methods.In this longitudinal study, we evaluated the relation of lead, measured in blood and tibia, to changes in blood pressure between 1994 and 1998. We studied 496 current and former employees of a chemical-manufacturing facility in the eastern United States who had previous occupational exposure to inorganic and organic lead. Cohort members who provided three or four blood pressure measurements during the study were included.Results.Mean age at baseline was 55.8 years with a mean of 18 years since last occupational exposure to lead. Blood lead at baseline averaged 4.6 &mgr;g/dL (standard deviation [SD] = 2.6) or 0.22 &mgr;mole/Liter (SD = 0.13). Tibia lead at year three averaged 14.7-&mgr;g/gm (SD = 9.4) bone mineral. Change in systolic blood pressure during the study was associated with lead dose, with an average annual increase of 0.64 mmHg (standard error [SE] = 0.25), 0.73 mmHg (SE = 0.26), and 0.61 mmHg (SE = 0.27) for every standard deviation increase in blood lead at baseline, tibia lead at year three, or peak past tibia lead, respectively.Conclusions.The results support an etiologic role for lead in the elevation of systolic blood pressure among adult males and are consistent with both acute and chronic modes of action.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The reasons for the increase in childhood asthma over time are unclear. The indoor environment is of particular concern. An adverse role for synthetic bedding on asthma development in childhood has been suggested by cross-sectional studies that have found an association between synthetic pillow use and childhood wheeze. Prospective data on infant bedding have not been available.Methods.Bedding data at 1 month of age were available from an infant survey for children who were participating in a 1995 follow-up study (N = 863; 78% traced). The 1995 follow-up was embedded in a larger cross-sectional survey involving 6,378 seven year olds in Tasmania (N = 92% of eligible). Outcome measures included respiratory symptoms as defined in the International Study of Asthma and Allergies in Childhood protocol. Frequent wheeze was defined as more than 12 wheeze episodes over the past year compared with no wheeze.Results.Synthetic pillow use at 1 month of age was associated with frequent wheeze at age 7 (adjusted relative risk [aRR] = 2.5; 95% confidence interval [CI] = 1.2–5.5) independent of childhood exposure. Current synthetic pillow and quilt use was strongly associated with frequent wheeze (aRR = 5.2; CI = 1.3–20.6). Substantial trends were evident for an association of increasing number of synthetic bedding items with frequent wheeze and with increasing wheeze frequency. Among children with asthma, the age of onset of asthma occurred earlier if synthetic bedding was used in infancy.Conclusions.In this cohort, synthetic bedding was strongly and consistently associated with frequent childhood wheeze. The association did not appear to be attributable to bedding choice as part of an asthma management strategy.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.For several decades, the incidence of pancreatic cancer has been 50% to 90% higher among blacks than among whites in the United States. The purpose of this study was to identify risk factors that may contribute to this racial disparity.Methods.We conducted a population-based case-control study of pancreatic cancer diagnosed in Atlanta (GA), Detroit (MI), and 10 New Jersey counties from August 1986 through April 1989. In-person interviews were exclusively with subjects (526 cases and 2153 population controls), rather than with next of kin.Results.The determinants of the higher incidence of pancreatic cancer among blacks than among whites differed by sex. Among men, established risk factors (ie, cigarette smoking, long-term diabetes mellitus, family history of pancreatic cancer) account for 46% of the disease in blacks and 37% in whites, potentially explaining all but 6% of the excess risk among blacks. Among women, however, other factors appear to contribute to the racial disparity, notably moderate/heavy alcohol consumption (>7 drinks per week) and elevated body mass index (above the first quartile). When these less accepted risk factors were combined with the established risk factors, 88% of the disease in black women and 47% in white women were explained, potentially accounting for all of the excess risk among blacks in our female study population.Conclusions.Among men, the established risk factors (mainly cigarette smoking and diabetes mellitus) explain almost the entire black/white disparity in incidence. Among women, however, other factors appear to contribute to the racial disparity, notably moderate/heavy alcohol consumption and elevated body mass index. In the absence of these factors, pancreatic cancer incidence rates among blacks probably would not exceed those among whites of either sex.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Tobramycin solution for inhalation (TOBI®; TSI) is indicated to treat patients with cystic fibrosis who are infected withPseudomonas aeruginosa.Preliminary findings from a randomized trial indicate that patients who received TSI had about half the mortality rate of those assigned to placebo.Methods.We used the Cystic Fibrosis Foundation registry data to conduct a retrospective cohort study of the risk of death among cystic fibrosis patients in 1999 according to their use of TSI during 1998. We controlled for age, lung function, height and infection withP. aeruginosa; other factors were not important confounders.Results.The crude risk of death among those who received TSI therapy for 4 or more months was 3.5 times greater than that among those who received no TSI (90% confidence interval = 3.0–4.2). In general, increased TSI use was related to progressive increases in the risk of death. Such a relation is expected because TSI is used for those who are close to death, resulting in strong confounding by indication. After control of the previously mentioned confounders, the estimated risk ratio was reduced from 3.5 to 1.2. Unfortunately, it is difficult to remove confounding by indication in its entirety. Using a method that estimates the magnitude of uncontrolled confounding, we show that the actual relation between TSI and the risk of death is likely to be protective, and may well be consistent with the results from the randomized trial.Conclusions.These data illustrate strong confounding by indication and the extent to which the interpretation of data can rest on assumptions about the data and its residual biases.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Numerous rare genetic conditions are known to influence fecundability in both males and females. It is less clear to what extent more subtle genetic differences influence fecundability on a population level.Methods.In 1994 a population-based survey was conducted among Danish twins born 1953–1982. Fecundability was assessed as the waiting time to pregnancy at the first attempt to achieve a pregnancy.Results.The reported time to pregnancy for males was slightly shorter than for females but there were no sex differences in intrapair similarity. We found an intrapair correlation in time to pregnancy for 645 monozygotic twin pairs (r = 0.22; 95% confidence interval = 0.12 to 0.32), but no intrapair correlation for 826 like-sex dizygotic twin pairs (r = 0.00; 95% confidence interval = −0.09 to 0.10).Conclusions.The correlation in time to pregnancy for monozygotic twins suggests genetic factors, although similarities in reporting behaviors could also be contributing to the correlation. The lack of correlation in time to pregnancy for dizygotic twins indicates that possible genetic factors of importance for fecundabililty are acting nonadditively. Hence, it may prove difficult to identify specific gene variants that influence fecundability on a population level if their effects depend on gene-gene interactions.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.The timing and magnitude of pubertal growth in relation to fetal, infancy and childhood growth have not been explored.Methods.We used data from a longitudinal growth study of 3650 full-term healthy children who were born in Gothenburg, Sweden in 1973–1975. This analysis included 2738 children with height and weight measurements available both in early life and during adolescence.Results.We found that faster linear growth during infancy and childhood was associated with earlier peak height velocity during adolescence. In contrast, greater height and body mass index (BMI) at birth were associated with later peak height velocity in adolescence. Children with faster linear growth and greater BMI in infancy and childhood had less height gain between ages 8 and 18. However, greater height and BMI at birth were associated with more height gain between ages 8 and 18 after adjusting for height and BMI in childhood.Conclusions.Both length and BMI (at birth, in infancy and during childhood) are associated with the timing and magnitude of pubertal growth. Being small at birth is associated with early puberty and a reduced height gain during adolescence.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Few studies have investigated socioeconomic status (SES) and external causes of death (ie, deaths attributable to injuries). These deaths are of particular interest because they are potentially preventable and they represent the second leading cause of years of life lost under age 75.Methods.We studied 261,723 deaths from external causes in 27 states from 1984 to 1997 among employed persons age 20–64. Numerator data came from occupation on the death certificate. Occupation-specific denominator data came from the U.S. Census. A Nam-Powers SES score was assigned to each occupation based on its relative income and education in the U.S. Census.Results.After adjusting for age, sex, year and race, SES was strongly associated with mortality from all external causes combined for men (rate ratios = 2.9, 2.3, 1.5, and 1.0 by ascending SES quartile), and to a lesser extent for women (rate ratios = 1.6, 1.0, 1.1, and 1.0). A similar pattern was seen for each of the specific external causes (motor vehicle deaths, suicide, homicide, injuries other than by motor vehicle, and medical complications).Conclusions.We estimate 41% of deaths from external causes are attributable to having a SES below the top quartile (both sexes combined).

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Background.Breast cancer incidence rates are up to five times higher in white women in the United States compared with Asian women in China and Japan. A search for factors that modify estrogen's biological effect differentially between ethnic groups may add to the understanding of international variations in breast cancer risk. Recent evidence indicates that alpha-fetoprotein, a glycoprotein produced by the fetal liver, has important antiestrogenic properties. During pregnancy, alpha-fetoprotein reaches peak concentrations in maternal serum during the third trimester.Methods.We compared pregnancy levels of alpha-fetoprotein in a population with high risk of breast cancer (Boston, MA) and low risk (Shanghai, China). Blood samples were collected around the 16th week and around the 27th week of gestation among women enrolled from March 1994 to October 1995. The number of specimens available for alpha-fetoprotein analysis was 1,033.Results.Alpha-fetoprotein levels, adjusted for gestational length, were substantially higher in Shanghai compared with Boston women at both time points. When adjustments were made for prepregnancy weight, parity, offspring's sex and maternal age, alpha-fetoprotein levels remained 13% higher in Shanghai at 16 weeks of pregnancy but not at 27 weeks.Conclusions.These findings may explain, at least in part, the difference in breast cancer risk between Chinese and American women. On the population level, alpha-fetoprotein may influence risk by modifying the effect of biologically active estrogens both in the mother and in female offspringin utero.

ISSN:1044-3983    

出版商:OVID    

年代:2003

数据来源: OVID