Biomedical subjects

M Sammel

Publications and source records attributed to M Sammel.

7 recordsLinked to original sources

PubMed2000

A scaled linear mixed model for multiple outcomes.

We propose a scaled linear mixed model to assess the effects of exposure and other covariates on multiple continuous outcomes. The most general form of the model allows a different exposure effect for each outcome. An important special case is a model that represents the exposure effects using a common global measure that can be characterized in terms of effect sizes. Correlations among different outcomes within the same subject are accommodated using random effects. We develop two approaches to model fitting, including the maximum likelihood method and the working parameter method. A key feature of both methods is that they can be easily implemented by repeatedly calling software for fitting standard linear mixed models, e.g., SAS PROC MIXED. Compared to the maximum likelihood method, the working parameter method is easier to implement and yields fully efficient estimators of the parameters of interest. We illustrate the proposed methods by analyzing data from a study of the effects of occupational pesticide exposure on semen quality in a cohort of Chinese men.

China↗

PubMed1999

Violent injuries among women in an urban area.

BACKGROUND: Although the rate of death from injuries due to violent acts is much higher among black women than among white women in the United States, little is known about the nature and correlates of violent injuries among black women living in urban areas. METHODS: In this case-control study conducted at three emergency departments in one inner-city community (in west Philadelphia), we studied 405 adolescent girls and women who had been intentionally injured and 520 adolescent girls and women (control subjects) who had health problems not related to violent injury. Data were collected by conducting standardized interviews with use of questionnaires and by screening urine for illicit drugs. Individual logistic-regression models were constructed to identify factors associated with violent injuries inflicted by partners and those inflicted by persons other than the partners of the victims. RESULTS: The male partners of the injured women were much more likely than the male partners of control subjects to use cocaine (odds ratio, 4.4; 95 percent confidence interval, 2.3 to 8.4) and to have been arrested in the past (odds ratio, 3.1; 95 percent confidence interval, 1.8 to 5.2). Fifty-three percent of violent injuries to the women had been perpetrated by persons other than their partners. Women's use of illicit drugs and alcohol abuse were factors associated with both violence on the part of partners and violence on the part of other persons. Neighborhood characteristics, including low median income, a high rate of change of residence, and poor education, were independently associated with the risk of violent injuries among women. CONCLUSIONS: Women in this urban, low-income community face violence from both partners and other persons. Substance abuse, particularly cocaine use, is a significant correlate of violent injuries. Standard Census data may help identify neighborhoods where women are at high risk for such violence and that would benefit from community-level interventions.

Adolescent↗

PubMed1999

Detailed examination of fenfluramine-phentermine users with valve abnormalities identified in Fargo, North Dakota.

Although several studies have reported on valve abnormalities among users of fenfluramine or dexfenfluramine, detailed information on these subjects has not been provided, limiting the ability to understand who may be at risk for valve abnormalities and to generate hypotheses about the etiology and pathogenesis of these abnormalities. This study was a detailed medical record review of 18 previously reported users of fenfluramine and phentermine, all with valve abnormalities on echocardiogram and 2 with surgical pathology. Both clinical characteristics and medication use were recorded by trained abstracters using a standardized data collection form. Two subjects (11%) had other possible etiologies of valve disease: a history of rheumatic fever and prescribed ergotamine. Three subjects (17%) had a history of migraine headaches and 4 (22%) had murmurs noted before using fenfluramine. Use of medications that may affect serotonin receptors was common: ergotamine (1 subject, 5%), selective serotonin reuptake inhibitors (6, 33%), sumatriptan (2, 11%), and mirtazapine (1, 5%). Prior medication and nonmedication allergies were recorded in 6 (33%) and 3 (17%) subjects, respectively. All subjects had symptoms possibly due to fenfluramine or phentermine side effects. This study raises the hypotheses that valvular heart disease among fenfluramine users may be less common than previously estimated, that serotonin excess may play a role in valve pathology, and that a patient's response to anorexigens and other medications may serve as a marker for increased risk. Further study is needed to test these hypotheses.

Adult↗

PubMed1999

The effect of dehydroepiandrosterone supplementation to symptomatic perimenopausal women on serum endocrine profiles, lipid parameters, and health-related quality of life.

Dehydroepiandrosterone (DHEA), an androgenic steroid hormone, exhibits an age-related decline. Perimenopausal women have only approximately 50% of peak DHEA levels. Despite limited scientific data, DHEA has gained recognition as a dietary supplement to reduce the symptoms of aging and improve well-being. This randomized, double-blind placebo-controlled trial examined the effects of 50 mg/day of oral DHEA supplementation, for 3 months, on 60 perimenopausal women with complaints of altered mood and well-being. Changes in the serum endocrine profile of women in the DHEA group were significantly greater than the placebo group, including a 242% [95% confidence interval (CI) +60.1, +423.9] increase in DHEAS, a 94.8% (95% CI +34.2, +155.4) increase in testosterone, and a 13.2% (95% CI -27.88, +0.5) decline in cortisol compared to baseline. Women receiving DHEA had a 10.1% (95% CI -15.0, -5.1) decline in high-density lipoprotein and an 18.1% (95% CI -32.2, -3.9) decline in Lp(a) from baseline, but these declines did not significantly differ from women who received placebo. Women receiving DHEA did not have any improvements significantly greater than placebo in the severity of perimenopausal symptoms, mood, dysphoria, libido, cognition, memory, or well-being. DHEA supplementation significantly effects the endocrine profile, may affect the lipid profile, but does not improve perimenopausal symptoms or well-being compared to placebo.

Affect↗

PubMed1998

Association of petrochemical exposure with spontaneous abortion.

OBJECTIVES: To assess the association between petrochemical exposure and spontaneous abortion, a retrospective epidemiological study in a large petrochemical complex in Beijing, China was conducted. METHODS: Plant employment records identified 3105 women who were married, were 20-44 years of age, and had never smoked. Of those, 3070 women (98.8%) reported at least one pregnancy. From this group, 2853 (93%) of the women participated in the study. According to their plant employment record, about 57% of these women workers reported occupational exposure to petrochemicals during the first trimester of their pregnancy. Trained interviewers administered a standardised questionnaire to this group of women and their husbands, collecting information on reproductive history, pregnancy outcomes, employment history, occupational exposure, smoking habits, alcohol consumption, indoor air pollution, and demographic variables. The results from the womens' first pregnancies were analysed. RESULTS: There was a significantly increased risk of spontaneous abortion for women working in all of the production plants with frequent exposure to petrochemicals (8.8%; range of 5.8%-9.8%) compared with those working in nonchemical plants (2.2%; range of 0.0%-7.1%). Also, when a comparison was made between exposed and non-exposed groups within each plant, exposure to petrochemicals was consistently associated with an increased risk of spontaneous abortion. The overall odds ratio (OR) was 2.7 (95% confidence interval (95% CI) 1.8 to 3.9) after adjusting for potential confounders. When the analysis was performed with the exposure information obtained from the women' interview responses for (self reported) exposures, the estimated OR for spontaneous abortions was 2.9 (95% CI 2.0 to 4.0). The analysis was repeated by excluding those 452 women who provided inconsistent reports between recalled exposure and work history, and a comparable risk of spontaneous abortion (OR 2.9; 95% CI 2.0 to 4.4) was found. In analyses for exposure to specific chemicals, an increased risk of spontaneous abortion was found with exposure to most chemicals, and the results for benzene (OR 2.5; 95% CI 1.7 to 3.7), gasoline (OR 1.8; 95% CI 1.1 to 2.9), and hydrogen sulphide (OR 2.3; 95% CI 1.2 to 4.4) were significant. CONCLUSION: An increased risk of spontaneous abortion was found associated with the exposure to petrochemicals, including benzene, gasoline, and hydrogen sulphide.

Abortion, Spontaneous↗

PubMedDate not supplied

Multivariate linear mixed models for multiple outcomes.

We propose a multivariate linear mixed (MLMM) for the analysis of multiple outcomes, which generalizes the latent variable model of Sammel and Ryan. The proposed model assumes a flexible correlation structure among the multiple outcomes, and allows a global test of the impact of exposure across outcomes. In contrast to the Sammel-Ryan model, the MLMM separates the mean and correlation parameters so that the mean estimation will remain reasonably robust even if the correlation is misspecified. The model is applied to birth defects data, where continuous data on the size of infants who were exposed to anticonvulsant medications in utero are compared to controls.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

Symptom reports from a cohort of African American and white women in the late reproductive years.

OBJECTIVE: To identify symptoms experienced in a cohort of healthy women in the late reproductive years; to compare symptom reports between African American and Caucasian women; and to determine the extent to which other factors in reproductive health, mood and behavior, lifestyle, and demographic background are associated with the reported symptoms. DESIGN: A cohort of women aged 35 to 47 years (mean age, 41 years) was identified through random digit dialing. This study is a cross-sectional analysis of data collected at enrollment from a subset of 308 women who completed daily symptom reports (DSR) for one menstrual cycle. Data were obtained in structured interviews and self-administered standard questionnaires. The associations of the study variables with symptoms as assessed by the DSR were examined using analysis of variance and general linear models. RESULTS: The African American women were significantly more likely to report in interview that they experienced menopausal symptoms (46% vs. 30%; p < 0.001) and had significantly higher ratings on the physiological symptom factor of the DSR, which included hot flashes, dizziness, poor coordination/clumsiness, urine leaks, and vaginal dryness. The DSR yielded two other factors of psychological and somatic symptoms. Race was associated only with the physiological symptom factor in the multivariable analyses. Neither race nor age were associated with psychological symptoms, which were predicted by current or past mood problems. CONCLUSIONS: Symptoms commonly associated with the menopause are experienced in the late reproductive years before observable changes in menstrual cycles. African American women reported more physiological symptoms than white women. These data provide an essential baseline for longitudinal study of symptoms associated with the ovarian decline in the perimenopausal years.

Adult↗