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Bootstrap methods for statistical inference from stereological estimates of volume fraction.

We suggest the use of bootstrap methods for inference from stereological estimates of volume fraction. An informal introduction to stereological estimation of volume fraction and to principles of bootstrap techniques is given. The bootstrap method is a robust computer-intensive resampling technique, based on independent random sampling from a data set with replacement. Bootstrap methods were used to estimate confidence intervals for volume fractions, and to test for a significant difference between estimated volume fractions from two samples. Two sampling designs are considered: independent replicated samples (visual fields) from a single object, and estimates of volume fraction from multiple independent objects. The methods are presented as worked examples on real data sets obtained from tumour pathology (mammary cancer, pancreatic cancer). The volume fraction of glandular lumina per total volume of the epithelial phase was chosen as target parameter. It indicates the degree of glandular differentiation in adenocarcinomas and is estimated as a ratio-of-means statistic with variable denominator within cases. The confidence intervals of the volume fraction estimated by the bootstrap method were slightly narrower than the parametrically calculated confidence intervals for all data sets. The outcomes of significance tests based on the bootstrap technique were unchanged as compared with classical tests based on the assumptions of normality and homoscedasticity of the data. Special attention was paid to the reproducibility of the bootstrap technique in replicated trials on the same data.

Breast Neoplasms↗

Concentration of endometrial protein PP14 in uterine flushings throughout the menstrual cycle in normal, fertile women.

OBJECTIVE: To determine the variation in concentration of endometrial protein PP14 in uterine flushings throughout the menstrual cycle comparing this to concentrations in plasma samples. DESIGN: Precise timing of all samples by the luteinising hormone surge. SETTING: Jessop Hospital for Women, Sheffield. SUBJECTS: Twenty-three regularly cycling, previously fertile volunteer women. INTERVENTIONS: Observational study; 10 ml of physiological saline was used to flush the uterine cavity once or serially in the cycle of the study. MAIN OUTCOME MEASURES: The measurement of PP14 levels by radioimmunoassay in uterine flushings and plasma samples. RESULTS: In uterine flushing, PP14 levels were not detectable in significant amounts in the proliferative phase and the early luteal phase; after day LH + 6, the concentration rises rapidly with a doubling time of only 6.6 to 14.6 h in the midluteal phase. In the late luteal phase, the concentrations in uterine flushing were over a hundred times higher than the corresponding plasma samples. CONCLUSIONS: The measurement of PP14 in uterine flushings is likely to be of greater value than the measurement in plasma samples; it may provide a valuable alternative to the evaluation of endometrial function.

Adult↗

Vaccination coverage and reasons for non-vaccination in a district of Istanbul.

BACKGROUND: In order to control and eliminate the vaccine preventable diseases it is important to know the vaccination coverage and reasons for non-vaccination. The primary objective of this study was to determine the complete vaccination rate; the reasons for non-vaccination and the predictors that influence vaccination of children. The other objective was to determine coverage of measles vaccination of the Measles Immunization Days (MID) 2005 for children aged 9 month to 6 years in a region of Umraniye, Istanbul, Turkey. METHODS: A '30 x 7' cluster sampling design was used as the sampling method. Thirty streets were selected at random from study area. Survey data were collected by a questionnaire which was applied face to face to parents of 221 children. A Chi-square test and logistic regression was used for the statistical analyses. Content analysis method was used to evaluate the open-ended questions. RESULTS: The complete vaccination rate for study population was 84.5% and 3.2% of all children were totally non-vaccinated. The siblings of non-vaccinated children were also non-vaccinated. Reasons for non-vaccination were as follows: being in the village and couldn't reach to health care services; having no knowledge about vaccination; the father of child didn't allow vaccination; intercurrent illness of child during vaccination time; missed opportunities like not to shave off a vial for only one child. In logistic regression analysis, paternal and maternal levels of education and immigration time of both parents to Istanbul were found to influence whether children were completely vaccinated or non-vaccinated. Measles vaccination coverage during MID was 79.3%. CONCLUSION: Efforts to increase vaccination coverage should take reasons for non-vaccination into account.

Attitude to Health↗

Racial/ethnic disparity and predictors of leisure-time physical activity among U.S. men.

OBJECTIVES: To examine racial/ethnic disparity in and predictors of leisure-time physical activity (LTPA) among men. METHODS: We used the National Health Interview Surveys (NHIS) 1999-2000 data, a multistage probability sampling design producing a U.S. representative sample of 23,459 adult males. Data were analyzed using multinomial logistic regression. RESULTS: The likelihood of engaging in irregular or regular LTPA was associated with younger age, being unmarried, lower household sizes, higher levels of education and income, home ownership, U.S. citizenship, perceived better health status, contact with a health professional within a year, being a non-smoker, living in the West, and residing in a midsize metropolitan statistical area. Hispanics were significantly less likely to engage in regular LTPA than Whites and higher percentages of Hispanics were physically inactive in almost all age and education groups when compared to other races. Disparity between Whites and Blacks was less pronounced. Non-citizen Hispanics were twice as likely to be inactive than citizens and White non-citizens were 40% more likely to be inactive than citizens. Conversely, Black citizens were 20% more likely to be inactive than non-citizens. CONCLUSIONS: Racial/ethnic disparities exist after accounting for socio-demographic characteristics. Not being a citizen exacerbates the disparity between Hispanic and White men. While disparity did exist between Black and White men, this gap was not as large as between Hispanic and White men. Health-seeking behaviors, such as contact with a health professional and non-smoking status are modifiable and influence men of all racial and ethnic backgrounds to engage in LTPA.

Adolescent↗

Correlates of drug abuse among homeless and transient people in the Washington, DC, metropolitan area in 1991.

Sociodemographic correlates of drug use among the general household population may have less accuracy and utility for describing risk factors for drug use among non household populations like the homeless and transient. This analysis examines correlates of past year use of marijuana, cocaine, and needles among homeless and transient people in the Washington, DC, metropolitan statistical area (DC MSA) and discusses them vis-a-vis traditional indicators of drug use among the general household population. Data are from a study conducted in the DC MSA in 1991 that used a multistage sampling design and surveyed a random sample of 908 homeless and transient people ages 12 years and older. The analysis uses multiple logistic regression to assess the independent effect of demographic and other predictors on selected drug use measures among this population. Three key socioeconomic correlates of drug use among the general household population (educational attainment, employment status, and marital status) were nonsignificant predictors of drug use among the homeless. However, other factors were significant, including past year institutionalization, location within the DC MSA, and stage of homelessness. The age group at greatest risk for use of marijuana and cocaine in the past year were the homeless ages 26 to 34, but the oldest group (35 years and older) had the highest risk of needle use. Although men were more likely to have used marijuana and cocaine in the past year, there were no sex differences in the use of needles in the past year. Only past year use of cocaine differed significantly by race or ethnicity, with a greater likelihood among homeless blacks than among homeless whites. Measures of social achievement and socioeconomic status related to the prevalence and risks of drug use among the general household population have but limited applicability in predicting drug use among people who are homeless and transient. Along with other indicators of behavioral and health risks,history of institutionalization, urbanization, and chronicity of homelessness should be considered to improve the epidemiologic assessment of this population.

Adolescent↗

[Food consumption and the nutritional status of schoolchildren of the Community of Madrid (CAENPE): general methodology and overall food consumption. Consumo de alimentos y estado nutricional de la población escolar].

The CAENPE study (Food Consumption and Nutritional State of the School Population) was a transversal observational study funded and promoted by the Directorate-General of Food Hygiene in the Ministry of Health, implemented in 1991-93, with the main aim of quantifying food consumption in the school population (6-14 years of age) in the Regional Community of Madrid, together with an anthropometric study and nutritional analysis of that population. This project sets our the General Methodology for the study, paying particular attention to the sampling design, to ensure that the sample is representative of the community, and the results of the overall consumption of food and its comparison with recommended diet and other population studies. Quantification shows a high and rising consumption of meat, meat products, sweets, snacks and prepared dishes, suitable consumption of eggs, legumes and fruit and a notable lack of greens, vegetables and potatoes. The basic results underline the need to introduce educational measures with practical effect on home and school menus.

Adolescent↗

Design and sample-size considerations in the detection of linkage disequilibrium with a disease locus.

The presence of linkage disequilibrium between closely linked loci can aid in the fine mapping of disease loci. We investigate the power of several designs for sampling individuals with different disease genotypes. As expected, haplotype data provide the greatest power for detecting disequilibrium, but, in the absence of parental information to resolve the phase of double heterozygotes, the most powerful design samples only individuals homozygous at the trait locus. For rare diseases, such a scheme is generally not feasible, and we also provide power and sample-size calculations for designs that sample heterozygotes. The results provide information useful in planning disequilibrium studies.

Chromosome Mapping↗

Population-based family study designs: an interdisciplinary research framework for genetic epidemiology.

Most complex traits such as cancer and coronary heart diseases are attributed either to heritable factors or to environmental factors or to both. Dissecting the genetic and environmental etiology of complex traits thus requires an interdisciplinary research strategy. Genetic studies generally involve families and investigate familial aggregations of traits, segregation of major disease genes, and locations of disease genes on the human genome, the latter of which can be identified via linkage analysis. Epidemiologic studies often use population-based case-control studies to establish the role of specific environmental factors. Integrating both objectives, genetic epidemiology is to assess the associations of environmental factors with disease status, to quantify the aggregation of cases within families, to characterize putative disease genes via segregation analysis, and to localize disease genes via linkage analysis with genetic markers. To accomplish these objectives through designed studies, we propose a class of population-based family study designs, which are formed by choosing among sampling designs at three stages. The objectives of sampling at these three stages are 1) combined aggregation and association analysis, 2) combined segregation, aggregation, and association analysis, and 3) combined linkage, segregation, aggregation, and association analysis. These designs form an interdisciplinary research framework for genetic epidemiology. Our preliminary exploration of this framework and related analytic methods indicates that population-based family study designs retain the efficiency of linkage analysis for localizing disease genes without losing the property of being population-based, and they will therefore allow an assessment of a joint contribution of genetic and environmental factors to complex traits.

Case-Control Studies↗

National Survey of Family Growth: design, estimation, and inference.

The purpose of this report is to document the procedures used in the 1988 National Survey of Family Growth (NSFG) to select the sample, weight the data to produce national estimates, impute missing data, and estimate sampling errors. Therefore, this report necessarily contains a great deal of technical detail. For readers who do not need this level of detail, this summary briefly describes the procedures used. The National Survey of Family Growth is conducted every few years by the National Center for Health Statistics (NCHS), a part of the U.S. Department of Health and Human Services. The purpose of the survey is to collect and publish data from a national sample of women on childbearing, factors affecting childbearing (such as contraception, sterilization, and infertility), and related aspects of maternal and infant health. Interviewing for Cycle IV of the survey was done in 1988 by Westat, Inc., under a contract with NCHS. Personal interviews were conducted between January and August of 1988 with a national sample of 8,450 women in the civilian noninstitutionalized population of the United States. Interviews were conducted in person by trained female interviewers and lasted an average of 70 minutes. The interview focused on the woman's pregnancies, if any; her use of contraception; her ability to bear children (fecundity and infertility); her use of medical services for family planning, infertility, and prenatal care; her marriage and cohabitation history, if any; and a wide range of demographic and economic characteristics. This report describes some of the main methodological aspects of the survey, including the sample design, weighting, sampling errors, and imputation of missing data. These topics will be described briefly and less technically in this summary. Each topic is discussed in more detail in the rest of the report.

Adolescent↗

Capturing momentary, self-report data: a proposal for reporting guidelines.

Self-report data are ubiquitous in behavioral and medical research. Retrospective assessment strategies are prone to recall bias and distortion. New techniques for assessing immediate experiences in respondents' natural environments (e.g., Ecological Momentary Assessment, Experience Sampling) are being used by many researchers to reduce reporting bias. This article discusses seven aspects of momentary research that are often overlooked or minimized in the presentation of momentary research reports, yet that are critical to the success of the research: (a) the rationale for the momentary sampling design, (b) the details of momentary sampling procedures, (c) the data acquisition interface, (d) rates of compliance with the sampling plan, (e) the procedures used to train and monitor participants, (f) data management procedures, and (g) the data analytic approach. Attention to these areas in both the design and reporting of momentary research studies will not only improve momentary research protocols but also allow for the successful replication of research findings by other investigators.

Guidelines as Topic↗

Youth Risk Behavior Surveillance--National Alternative High School Youth Risk Behavior Survey, United States, 1998.

PROBLEM/CONDITION: Alternative high schools serve approximately 280,000 students nationwide who are at high risk for failing or dropping out of regular high school or who have been expelled from regular high school because of illegal activity or behavioral problems. Such settings provide important opportunities for delivering health promotion education and services to these youth and young adults. However, before this survey, the prevalence of health-risk behaviors among students attending alternative high schools nationwide was unknown. REPORTING PERIOD: February-May 1998. DESCRIPTION OF SYSTEM: The Youth Risk Behavior Surveillance System (YRBSS) monitors the following six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The national Alternative High School Youth Risk Behavior Survey (ALT-YRBS) is one component of the YRBSS; it was conducted in 1998 to measure priority health-risk behaviors among students at alternative high schools. The 1998 ALT-YRBS used a three-stage cluster sample design to produce a nationally representative sample of students in grades 9-12 in the United States who attend alternative high schools. The school response rate was 81.0%, and the student response rate was 81.9%, resulting in an overall response rate of 66.3%. This report summarizes results from the 1998 ALT-YRBS. RESULTS AND INTERPRETATION: In the United States, 73.6% of all deaths among youth and young adults aged 10-24 years results from only four causes--motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1998 ALT-YRBS demonstrate that many students at alternative high schools engage in behaviors that increase their likelihood of death from these four causes. During the 30 days preceding the survey, 51.9% had ridden with a driver who had been drinking alcohol, 25.1% had driven a vehicle after drinking alcohol, 32.9% had carried a weapon, 64.5% had drunk alcohol, and 53.0% had used marijuana. During the 12 months preceding the survey, 15.7% had attempted suicide, and 29.0% had rarely or never worn a seat belt. Substantial morbidity among school-aged youth and young adults also results from unintended pregnancies and STDs, including HIV infection. ALT-YRBS results indicate that in 1998, a total of 87.8% of students at alternative high schools had had sexual intercourse, 54.1% of sexually active students had not used a condom at last sexual intercourse, and 5.7% had ever injected an illegal drug. Among adults aged > or =25 years, 66.5% of all deaths result from two causes--cardiovascular disease and cancer. Most risk behaviors associated with these causes of death are initiated during adolescence. In 1998, a total of 64.1% of students at alternative high schools had smoked cigarettes during the 30 days preceding the survey, 38.3% had smoked a cigar during the 30 days preceding the survey, 71.2% had not eaten > or =5 servings of fruits and vegetables during the day preceding the survey, and 81.0% had not attended physical education (PE) class daily. Comparing ALT-YRBS results with 1997 national YRBS results demonstrates that the prevalence of most risk behaviors is higher among students attending alternative high schools compared with students at regular high schools. Some risk behaviors are more common among certain sex and racial/ethnic subgroups of students. PUBLIC HEALTH ACTION: ALT-YRBS data can be used nationwide by health and education officials to improve policies and programs designed to reduce risk behaviors associated with the leading causes of morbidity and mortality among students attending alternative high schools.

Adolescent↗

Spanish population at risk of unwanted pregnancy: results of a national survey.

OBJECTIVE: We performed a personal survey in 2218 Spanish women aged from 15 to 49 years to establish the contraceptive methods used by this population and to determine the number of Spanish women of childbearing age exposed to unwanted pregnancy. METHODS: Stratified random sampling was performed to select the women to be interviewed; this sampling design ensured adequate representation of the sample in Spain. RESULTS: At the time of the survey, 69.1% of the women were using some contraceptive method, but 5% of them used poorly effective contraceptive methods, and their exposure to the risk of an unwanted pregnancy was therefore high. Moreover, among the 30.9% not using any contraceptive method, 21.1% were at risk because they were having sexual intercourse, did not want to become pregnant and did not use a contraceptive method. CONCLUSIONS: A little over one million Spanish women are exposed to the risk of having an unwanted pregnancy. Compiling the data on this significant problem is the first step in designing appropriate solutions.

Adolescent↗

Multilevel modelling of built environment characteristics related to neighbourhood walking activity in older adults.

OBJECTIVE: To examine the relation between built environment factors (representing several dimensions of urban form of neighbourhoods) and walking activity at both the neighbourhood level and the resident level, in an older adult sample. DESIGN, SETTING, PARTICIPANTS: A cross sectional, multilevel design with neighbourhoods as the primary sampling unit and senior residents as the secondary unit. Five hundred and seventy seven residents (mean age = 74 years, SD = 6.3 years) participated in the survey, which was conducted among 56 city defined neighbourhoods in Portland, Oregon, USA. Neighbourhood level variables were constructed using geographical information systems. Resident level variables consisted of a mix of self reports and geocoded data on the built environment. MAIN OUTCOME MEASURE: Self reported neighbourhood walking. MAIN RESULTS: A positive relation was found between built environment factors (density of places of employment, household density, green and open spaces for recreation, number of street intersections) and walking activity at the neighbourhood level. At the resident level, perceptions of safety for walking and number of nearby recreational facilities were positively related to high levels of walking activity. A significant interaction was observed between number of street intersections and perceptions of safety from traffic. CONCLUSIONS: Certain neighbourhood built environment characteristics related to urban form were positively associated with walking activity in the neighbourhoods of senior residents. Public health promotion of walking activity/urban mobility and the design of interventions need to consider the contribution of neighbourhood level built environment influences.

Aged↗

The New Zealand Partner Relations Survey: methodological results of a national telephone survey.

OBJECTIVE: To implement and evaluated a national survey of sexual behaviour using computer-assisted telephone interviewing (CATI). DESIGN: A two-stage stratified national sample survey in which households were selected by random digit-dialing (RDD), with a single eligible interviewee per selected household, followed by subsample surveys of non-contacts and refusals to determine eligibility. METHODS: A 15-minute questionnaire based on the Global Programme on AIDS (GPA)/World Health Organization (WHO) protocol was administered by telephone to a nationally representative sample of 2361 respondents in the 18-54-year age group. RESULTS: The overall response rate was 63%, but lower in the cities, in the 18-24 age group, and among men. Three-quarters of surveyed non-contacts, and a quarter of re-surveyed refusals, did not meet the eligibility criteria for the study. Less than 20% of refusals cited the subject matter of the survey as the reason for refusal. Item non-response (< 1%) increased with question sensitivity, and varied by respondent age, ethnicity and partnership status. Men reported twice as many adult lifetime partners as women. CONCLUSIONS: The GPA/WHO protocol can be successfully adapted to administration by telephone, with adequate response rates and exceptionally low levels of item non-response. CATI is a cost-effective method for collecting national information on sexual behaviour in countries where there is a high level of telephone ownership. Used in conjunction with RDD, it can overcome problems of sample design in settings where there is no comprehensive population-sampling frame. Checks on item sensitivity and partner estimates suggest that acceptable levels of reliability can also be achieved.

Adolescent↗

Youth risk behavior surveillance. National Alternative High School Youth Risk Behavior Survey, United States, 1998.

Alternative high schools serve approximately 280,000 students nationwide who are at high risk for failing or dropping out of regular high school or who have been expelled from regular high school because of illegal activity or behavioral problems. Such settings provide important opportunities for delivering health promotion education and services to these youth and young adults. However, before this survey, the prevalence of health-risk behaviors among students attending alternative high schools nationwide was unknown. The Youth Risk Behavior Surveillance System (YRBSS) monitors the following six categories of priority health-risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries; tobacco use; alcohol and other drug use; sexual behaviors that contribute to unintended pregnancy and sexually transmitted diseases (STDs) (including human immunodeficiency virus [HIV] infection); unhealthy dietary behaviors; and physical inactivity. The national Alternative High School Youth Risk Behavior Survey (ALT-YRBS) is one component of the YRBSS; it was conducted in 1998 to measure priority health-risk behaviors among students at alternative high schools. The 1998 ALT-YRBS used a three-stage cluster sample design to produce a nationally representative sample of students in grades 9-12 in the United States who attend alternative high schools. The school response rate was 81.0%, and the student response rate was 81.9%, resulting in an overall response rate of 66.3%. This report summarizes results from the 1998 ALT-YRBS. The reporting period is February-May 1998. In the United States, 73.6% of all deaths among youth and young adults aged 10-24 years results from only four causes--motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1998 ALT-YRBS demonstrate that many students at alternative high schools engage in behaviors that increase their likelihood of death from these four causes. During the 30 days preceding the survey, 51.9% had ridden with a driver who had been drinking alcohol, 25.1% had driven a vehicle after drinking alcohol, 32.9% had carried a weapon, 64.5% had drunk alcohol, and 53.0% had used marijuana. During the 12 months preceding the survey, 15.7% had attempted suicide, and 29.0% had rarely or never worn a seat belt. Substantial morbidity among school-aged youth and young adults also results from unintended pregnancies and STDs, including HIV infection. ALT-YRBS results indicate that in 1998, a total of 87.8% of students at alternative high schools had had sexual intercourse, 54.1% of sexually active students had not used a condom at last sexual intercourse, and 5.7% had ever injected an illegal drug. Among adults aged > or = 25 years, 66.5% of all deaths result from two causes--cardiovascular disease and cancer. Most risk behaviors associated with these causes of death are initiated during adolescence. In 1998, a total of 64.1% of students at alternative high schools had smoked cigarettes during the 30 days preceding the survey, 38.3% had smoked a cigar during the 30 days preceding the survey, 71.2% had not eaten > or = 5 servings of fruits and vegetables during the day preceding the survey, and 81.0% had not attended physical education (PE) class daily. Comparing ALT-YRBS results with 1997 national YRBS results demonstrates that the prevalence of most risk behaviors is higher among students attending alternative high schools compared with students at regular high schools. Some risk behaviors are more common among certain sex and racial/ethnic subgroups of students. ALT-YRBS data can be used nationwide by health and education officials to improve policies and programs designed to reduce risk behaviors associated with the leading causes of morbidity and mortality among students attending alternative high schools.

Adolescent↗

Predictors and prevalence of erectile dysfunction in a racially diverse population.

BACKGROUND: To our knowledge, the burden of disease attributed to erectile dysfunction (ED) has not been adequately quantified across a complete spectrum of age and race using a global disease definition, as recommended by the National Institutes of Health consensus statement. To obtain a better understanding of the national estimates of prevalence and risk factors for ED, we analyzed data from the 2001-2002 National Health and Nutrition Examination Survey. METHODS: The National Health and Nutrition Examination Survey collects data by household interview. The sample design is a stratified, multistage, probability sample of clusters of persons representing the civilian noninstitutionalized population. Data include medical histories in which specific queries are made regarding urological symptoms (including ED). These items were selected for analysis in 3566 men, 20 years and older. RESULTS: In men 20 years and older, ED affected almost 1 in 5 respondents. Hispanic men were more likely to report ED (odds ratio [OR], 1.89), after controlling for other factors. The prevalence of ED increased dramatically with advanced age; 77.5% of men 75 years and older were affected. In addition, there were several modifiable risk factors that were independently associated with ED, including diabetes mellitus (OR, 2.69), obesity (OR, 1.60), current smoking (OR, 1.74), and hypertension (OR, 1.56). CONCLUSIONS: The burden of ED on the US population is significant. Hispanic men had an elevated risk for ED, a finding that requires confirmation in prospective studies. Obesity, hypertension, smoking, and diabetes mellitus are significantly associated with ED risk. Mitigation of these risk factors may ameliorate the burden of ED.

Adult↗

Epidemiology of major depression in four cities in Mexico.

Analyses were conducted to estimate lifetime and current prevalence of major depressive disorder (MDD) for four representative cities of Mexico, to identify variables that influence the probability of MDD, and to further describe depression in Mexican culture. A multistage probability sampling design was used to draw a sample of 2,509 adults in four different regions of Mexico. MDD was assessed according to DSM-IV criteria by using the Composite International Diagnostic Interview collected by trained lay interviewers. The prevalence of MDD in these four cities averaged 12.8% for lifetime and 6.1% for the previous 12 months. MDD was highly comorbid with other mental disorders. Women were more likely to have lifetime MDD than were men. Being divorced, separated, or widowed (compared to married or never married) and having experienced childhood trauma were related to higher lifetime prevalence but not to current prevalence. In addition, age and education level were related to current 12-month MDD. Data on the profile of MDD in urban Mexico are provided. This research expands our understanding of MDD across cultures.

Adolescent↗

Covariates of cervical cytokine mRNA expression by real-time PCR in adolescents and young women: effects of Chlamydia trachomatis infection, hormonal contraception, and smoking.

Measurements of mucosal immune parameters in the uterine cervix are potentially influenced by numerous factors, including infections, endogenous and exogenous hormones, semen, and nicotine and its metabolites in cervical mucus. The objective of this study was to examine correlates of immunoregulatory cytokine mRNA expression in cervical cytology samples in a cross-sectional design. Samples, collected at study entry by cervical cytology brush from 368 women aged 13-21 enrolled in a longitudinal study of the natural history of human papillomavirus (HPV) infection, were tested by quantitative RT-PCR for expression of IFN-gamma, IL-4, IL-10, and IL-12. In a multivariate analysis, elevated levels of IFN-gamma, IL-10, and IL-12 were significantly (p < 0.05) associated with several variables, including current C. trachomatis infection, recent intercourse, and current oral contraceptive pill use. Suppressed IL-4 and IL-10 levels were associated with cigarette smoking within the last 24 h. Time since last menstrual period did not affect any of the cytokines; in a substudy of weekly cytokine variability, however, IL-10 showed a non-significant trend toward higher levels around the time of menstruation.

Adolescent↗