Biomedical subjects

T D Tosteson

Publications and source records attributed to T D Tosteson.

50 records · Page 3Linked to original sources

PubMed1993

Lung function, pre- and post-natal smoke exposure, and wheezing in the first year of life.

The relationship between initial level of lung function and subsequent wheezing, lower respiratory illness (LRI) was studied in 97 infants in whom the first measurement of pulmonary function (PFT) was made before 6 months of age. Occurrence of LRI was evaluated by standardized questionnaires at each well-baby visit, biweekly telephone calls to mothers, and review of all visits to physicians. Infant PFT was assessed by partial expiratory flow-volume curves and helium-dilution measurement of functional residual capacity (FRC). Maternal, prenatal smoking was assessed by urine cotinine and standard questionnaires. Infants who developed an LRI during the first year of life had lower preillness length-corrected forced expiratory flow at FRC (VFRC) than those who did not experience an LRI (males, 2.06 +/- 0.20 versus 2.32 +/- 0.29 ml/s/cm; females, 2.38 +/- 0.20 versus 2.91 +/- 0.26 ml/s/cm). Similar results were observed with FRC-corrected VFRC. No differences were observed for FRC. Differences in lung function were greatest in female infants whose mothers did not smoke during pregnancy (VFRC 2.67 +/- 0.25 versus 3.49 +/- 0.26 ml/s/cm for those with and without LRI, respectively; p = 0.03). History of maternal wheezing was more common in infants who experience an LRI, independent of maternal smoking. The results were not influenced by exposure to nonmaternal sources of environmental tobacco smoke in the postnatal period. Regression analyses that included data for multiple measurements of VFRC over the first year and took account of duration of follow-up demonstrated that lower levels of VFRC were associated with an increased frequency of LRI, especially in female infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

PubMed1992

A long-term study of mortality in men who have undergone vasectomy.

BACKGROUND: Vasectomy is a reliable and widely accepted method of contraception, but there is some uncertainty and few data about a possible long-term adverse effect on health. METHODS: We examined the relation between vasectomy and mortality rates from cardiovascular disease, cancer, and all causes in a retrospective cohort of husbands of members of the Nurses' Health Study. In 1989 we obtained data by questionnaire on 14,607 men who had undergone vasectomy as of 1976 and 14,607 men who had not. RESULTS: Among the men who were free of cancer at the start of the study, 1052 died: 446 of cardiovascular disease, 341 of cancer, and 265 of other causes. Vasectomy was associated with reductions in mortality from all causes (age-adjusted relative risk, 0.85; 95 percent confidence interval, 0.76 to 0.96) and mortality from cardiovascular disease (relative risk, 0.76; 95 percent confidence interval, 0.63 to 0.92). Vasectomy was unrelated to mortality from all forms of cancer (relative risk, 1.01; 95 percent confidence interval, 0.82 to 1.25). Among men who had a vasectomy at least 20 years earlier, the procedure had no relation to mortality from all causes (relative risk, 1.11; 95 percent confidence interval, 0.92 to 1.33) or that from cardiovascular disease (relative risk, 0.85; 95 percent confidence interval, 0.63 to 1.16). However, mortality from cancer was increased in men who had a vasectomy at least 20 years earlier (relative risk, 1.44; 95 percent confidence interval, 1.07 to 1.92). The excess risk of cancer in these men was due primarily to lung cancer. None of the observed associations were confounded by smoking habits, body-mass index, alcohol consumption, or educational level. CONCLUSIONS: Vasectomy is not associated with an increase in overall mortality or mortality from cardiovascular disease. Our study also found no increase in overall mortality from cancer after vasectomy, but there was an apparent increase in the risk of cancer 20 or more years after vasectomy that requires further study.

Adult↗

PubMed1992

Effects of asthma on pulmonary function in children. A longitudinal population-based study.

Data from a longitudinal study of childhood factors influencing the development of chronic obstructive lung disease were used to assess the effects of asthma on lung function development in male and female children. A population-based cohort of 602 white children, initially aged 5 to 9 yr, was observed prospectively for 13 yr. Spirometry was performed and a standardized respiratory and illness questionnaire was administered by trained interviewers on a yearly basis. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and forced expiratory flow between 25 and 75% of vital capacity (FEF25-75) were used as measures of lung function. The total number of children reporting asthma over the course of the study was 67. Male asthmatic subjects (n = 42) had larger average percentage of predicted FVC than nonasthmatic males (n = 277). Female asthmatic subjects (n = 23) had a lower average percentage of predicted FEV1 than nonasthmatic females (n = 260). In a multivariate analysis of the individual lung function measures, adjusting for previous level of pulmonary function, age, height, change in height, and personal and maternal smoking, males reporting active asthma had a significantly larger FVC than males with no history of asthma. In contrast, females with active asthma had a significantly smaller FEV1 than females with no history of asthma. Both males and females with active asthma had decreased FEF25-75. From our analysis, we would predict that a female who develops asthma at age 7 would experience a 5% reduction in FEV1 by age 10 and a 7% deficit by age 15.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗

PubMed1992

The effect of maternal smoking during pregnancy on early infant lung function.

We studied the effect of prenatal maternal cigarette smoking on the pulmonary function (PF) of 80 healthy infants tested shortly after birth (mean, 4.2 +/- 1.9 wk). Mothers' prenatal smoking was measured by: (1) questionnaire reports at each prenatal visit of the number of cigarettes smoked per day, and (2) urine cotinine concentrations (corrected for creatinine) obtained at each visit. Infant PF was assessed by partial expiratory flow-volume curves and helium-dilution measurement of FRC. Forced expiratory flow rates were significantly lower in infants born to smoking mothers, both when unadjusted and after controlling for infant size, age, sex, and passive exposure to environmental tobacco smoke (ETS) between birth and the time of PF testing. Flow at functional residual capacity (VFRC) in infants born to smoking mothers was lower than that found in infants whose mothers did not smoke during pregnancy (74.3 +/- 15.9 versus 150.4 +/- 8.9 ml/s; p = 0.0007). Differences remained significant when flow was corrected for lung size (VFRC/FRC: 0.87 +/- 0.26 versus 1.77 +/- 0.12 s-1; p = 0.013). No differences in pulmonary function were evident among infants exposed and unexposed to ETS in the home after stratifying by prenatal exposure status. We conclude that maternal smoking during pregnancy is associated with significant reductions in forced expiratory flow rates in young infants. The results suggest that maternal smoking during pregnancy may impair in utero airway development and/or alter lung elastic properties. We speculate that these effects of maternal prenatal smoking on early levels of forced expiratory flow may be an important factor predisposing infants to the occurrence of wheezing illness later in childhood.

Adult↗

PubMed1992

Effects of chain length on the immunogenicity in rabbits of group B Streptococcus type III oligosaccharide-tetanus toxoid conjugates.

One method to improve the immunogenicity of polysaccharide antigens is the covalent coupling of the native polysaccharide or a derivative oligosaccharide to a carrier protein. In general, T cell-dependent properties are enhanced in conjugates of smaller saccharides, but a conformational epitope of the native polysaccharide may be better expressed in conjugates of larger saccharides. We have reported previously the synthesis and immunogenicity in animals of an oligosaccharide-tetanus toxoid conjugate vaccine against type III group B Streptococcus. In this study, we sought to determine the optimal size of group B Streptococcus type III oligosaccharide for use in a conjugate vaccine by evaluating the relative immunogenicity of conjugate vaccines containing oligosaccharides that were twofold smaller (7,000 Mr) or larger (27,000 Mr) than that reported previously (14,500 Mr). All three type III oligosaccharide conjugate vaccines were immunogenic in rabbits, in contrast to native, uncoupled group B Streptococcus type III polysaccharide. However, with respect to eliciting specific antibodies that were protective in vivo, the vaccine containing the intermediate-size oligosaccharide was superior to the smaller or larger conjugate vaccine. Analysis of opsonic activity of vaccine-induced antibodies demonstrated a predominance of IgG antibodies, thought to reflect T cell dependence, in response to shorter chain length conjugates, while the conformational epitope of the native polysaccharide was maximally expressed on longer chain length conjugates. These opposing trends may account for the optimal immunogenicity of an intermediate-size group B Streptococcus type III oligosaccharide conjugate vaccine.

Animals↗

PubMed1992

Rotating shift work, sleep, and accidents related to sleepiness in hospital nurses.

A hospital-based survey on shift work, sleep, and accidents was carried out among 635 Massachusetts nurses. In comparison to nurses who worked only day/evening shifts, rotators had more sleep/wake cycle disruption and nodded off more at work. Rotators had twice the odds of nodding off while driving to or from work and twice the odds of a reported accident or error related to sleepiness. Application of circadian principles to the design of hospital work schedules may result in improved health and safety for nurses and patients.

Accidents, Occupational↗

PubMed1991

Logistic regression for clustered binary data in proband studies with application to familial aggregation of sleep disorders.

Estimation is considered for the class of conditional logistic regression models for clustered binary data proposed by Qu et al. (Communications in Statistics, Series A 16, 3447-3476, 1987) when clusters are sampled on the basis of the outcome for one or more cluster members. The problem is suggested by data from a study designed to investigate familial aggregation of sleep disorders. After appropriate consideration of the mode of ascertainment of "cases" and "controls," it is shown that the model is preserved under this form of sampling, and a method of estimation is presented. The inconsistency of two alternative methods is demonstrated, and an example is provided.

Biometry↗

PubMed1990

Antibody to the capsular polysaccharide/adhesin protects rabbits against catheter-related bacteremia due to coagulase-negative staphylococci.

A rabbit model of catheter-related bacteremia was developed to study immunity to the capsular polysaccharide/adhesin (PS/A) of coagulase-negative staphylococci. Catheters colonized by coagulase-negative staphylococci were inserted into the right jugular vein and attached to a subcutaneous osmotic pump, and blood cultures were obtained over 14 days. Nonimmune rabbits were bacteremic for 6-8 days after infection, hypoglycemic, and hyperlipidemic and had strong immune responses to teichoic acid but not to PS/A. PS/A immunization, but not teichoic acid immunization, reduced the number of bacteremic days by approximately 60%, diminished the hypoglycemia and hyperlipidemia, and ablated the immune responses to teichoic acid. Passive infusion of PS/A-specific polyclonal and monoclonal antibodies using a separate, noninfected catheter-pump combination implanted in the left jugular protected against both bacteremia and hematogenous colonization of this contralateral catheter.

Animals↗

PubMed1990

Early childhood predictors of asthma.

To investigate potential risk factors for the development of childhood asthma, the authors undertook a longitudinal study using a cohort of 770 children aged 5-9 years from East Boston, Massachusetts, that has been under study since 1975. The disease outcome considered was age at first onset of asthma, as determined by parental or self-reporting of a physician's diagnosis. Potential risk factors were evaluated specifically in relation to their presence antecedent to a diagnosis of asthma. Standardized questionnaires were used to obtain childhood illness histories, environmental exposures, and the asthmatic and atopic statuses of first-degree relatives. Ninety-one cases of asthma were identified from 1975 to 1988 (57 males and 34 females). Significant sex-adjusted relative risk estimates were seen for antecedent pneumonia, bronchitis, hay fever, sinusitis, parental asthma, and parental atopy. Neither bronchiolitis, eczema, croup, personal cigarette smoking, maternal smoking, paternal smoking, nor delivery complications bore an apparent relation to the development of asthma. A history of parental asthma or parental atopy did not significantly alter the sex-adjusted relative risk estimates for pneumonia, bronchitis, hay fever, or sinusitis. These results support the hypothesis that asthma is a multifactor disease whose expression is dependent on both familial and environmental influences.

Asthma↗

PubMed1989

A measurement-error model for binary and ordinal regression.

Exposure assessment poses special problems in air pollution epidemiology. This paper proposes a probit regression model for binary and ordinal outcomes that uses exposure validation information to develop estimates for the coefficient of the true exposure when only the inaccurate 'surrogate' measure of exposure is available for the individuals in the health study. This method is closely related to recently developed measurement-error methods, and is based on the assumption that the outcome and the surrogate exposure are conditionally independent given the true exposure. A test statistic is proposed for checking this conditional independence assumption when more than one surrogate is available, and an interpretation of the coefficient estimate is provided in the event that the assumption is violated. The methods are applied to an example involving nitrogen dioxide exposure and wheeze in children.

Air Pollution↗

PubMed1989

Acute lower respiratory illness in childhood as a predictor of lung function and chronic respiratory symptoms.

This study investigated the relationship of acute lower respiratory illness (LRI) to level and change in level of forced expiratory volumes in a cohort of 801 children, followed longitudinally for a maximum of 13 yr. The co-occurrence of respiratory illness before 2 yr of age and two or more LRI during a single surveillance year was associated with a 20.3% lower mean cross-sectional level of FEF25-75, and with reduced longitudinal change in level of FEF25-75. The effect of LRI on lung function was uniformly stronger for boys than for girls. Of the children with illness before 2 yr of age and two or more LRI, six of 14 were male asthmatics with mean levels of FEF25-75 that were lower than those of other asthmatic children. Pneumonia and/or hospitalization for respiratory illness prior to the onset of study were associated with lower cross-sectional levels of forced expiratory volumes at entry to the study, even when asthmatics/persistent wheezers were eliminated from the analysis (6.1% lower level of FEV1 for a nonasthmatic boy with previous hospitalization versus a nonasthmatic boy without hospitalization). In the longitudinal analysis, pneumonia and/or hospitalization were associated with slower increase in level of forced expiratory volumes, even after adjusting for "ever diagnosis of asthma/current any wheeze" (starting at the same leve, after eight years a boy with hospitalization would develop a 5.0% lower FEV1 than a boy without hospitalization). Acute LRI also was evaluated as a predictor of chronic respiratory symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMedDate not supplied

Periodic health examinations and the provision of cancer prevention services.

OBJECTIVES: To learn about cancer prevention services in primary care practices and to understand physician factors that affect the provision of these services. DESIGN: Survey of physicians and their patients in 1992. SETTING: Cooperating physicians (n = 72) of a random selection of community general internist and family physician practices in New Hampshire and Vermont. PATIENTS: Patients (n = 2775) of the study physicians for at least 1 year, aged 42 years or older, with no life-threatening threatening illness, who recently visited the physician. MAIN OUTCOME MEASURES: Proportion of sample patients per practice provided age- and sex-appropriate cancer prevention services in the previous year. RESULTS: In this primary care population, a high proportion of patients received appropriate services in 1992. A periodic health examination within the past year was an important predictor for the receipt of many cancer prevention services. Female physicians provided more periodic health examinations than male physicians; internists provided more than family physicians. CONCLUSIONS: The strongest determinant of receiving preventive services is having a periodic health examination. If clinicians and policymakers decrease emphasis on the periodic health examination as a major opportunity to provide indicated preventive services, they should ensure that a satisfactory alternative strategy is in place.

Adult↗

PubMedDate not supplied

Cancer early-detection services in community health centers for the underserved. A randomized controlled trial.

BACKGROUND: Achieving cancer early-detection goals remains a challenge, especially among low-income and minority populations. DESIGN/SETTING: A randomized trial based in 62 community health centers for the underserved in New York, New Jersey, and western Connecticut. Family physicians were on staff at most of the centers. INTERVENTION: Workshops, materials, and ongoing advice for center leaders promoted implementation of a preventive services office system to identify patients in need of services at each visit through use of medical record flow sheets, other tools, and staff involvement. EVALUATION END POINTS: The proportion of randomly selected patients by center who were up to date for indicated services at baseline (n = 2645) and follow-up (n = 2864) record review. RESULTS: Only 1 service (breast self-examination advice) increased more in intervention centers. Seven of 8 target services increased significantly for the 62 centers overall. During the study, the medical director changed in 26 centers (42%). Keeping the same medical director at intervention centers was associated with improvements in services. CONCLUSIONS: Cancer early-detection services are improving in community health centers, but the intervention had only a small impact, as determined by record review. To have an impact, the intervention required that there be no change in medical director. The relationship of changes in the practice environment to services delivered is complex and deserves more study.

Aged↗

PubMedDate not supplied

Epidemiological use of rectal proliferation measures.

Measures of rectal mucosal proliferation have been developed and used in research clinical settings, but their utility for larger-scale epidemiological studies remains uncertain. We assessed the suitability of bromodeoxyuridine (BrdUrd) and proliferating cell nuclear antigen (PCNA)-labeling indices (LIs) in the setting of a multicenter clinical trial of adenoma recurrence. Subjects at participating practices were asked to permit biopsy of normal rectal mucosa during a colonoscopy scheduled for other reasons. PCNA and BrdUrd labeling was performed, and corresponding LIs were computed. In general, subjects were willing to undergo biopsy during their scheduled procedures; less than 10% refused. Specimen preparation for PCNA was acceptable; the mean number of scorable crypts (+/- SE) was 12.99 +/- 0.37. Preparation for BrdUrd labeling was less successful, with a higher proportion of unscorable specimens and a lower mean number of scorable crypts. Among the 54 specimens with both LIs computed, the LI for PCNA was modestly higher than that for BrdUrd LI (4.1 +/- 0.2 and 3.7 +/- 0.2 respectively; P = 0.03). The rank order correlation between the two indices was 0.38). There was variation across centers in the PCNA LIs but few differences according to number of crypts scored. Measurement of rectal mucosal proliferation is feasible among endoscopy patients in large studies if PCNA is used; BrdUrd seems more difficult. The relationship between these two labels requires further study.

Adenoma↗