Is there an optimal sampling time and number of samples for assessing exposure to fast elimination endocrine disruptors with urinary biomarkers?

In studies investigating the effects of endocrine disruptors (ED) such as phthalates, bisphenols and some pesticides on human health, exposure is usually characterized with urinary metabolites. The variability of biomarkers concentration, due to rapid elimination from the body combined with frequent exposure is however pointed out as a major limitation to exposure assessment. This study was conducted to assess variability of urinary metabolites of ED, and to investigate how sampling time and number of samples analyzed impacts exposure assessment. Urine samples were collected over 6 months from 16 volunteers according to a random sampling design, and analyzed for 16 phthalate metabolites, 9 pesticide metabolites and 4 bisphenols. The amount of biomarkers excreted in urine at different times of the day were compared. In parallel, 2 algorithms were developed to investigate the effect of the number of urine samples analyzed per subject on exposure assessment reliability. In the 805 urine samples collected from the participants, all the biomarkers tested were detected, and 18 were present in >90% of the samples. Biomarkers variability was highlighted by the low intraclass correlation coefficients (ICC) ranging from 0.09 to 0.51. Comparing the amount of biomarkers excreted in urine at different time did not allow to identify a preferred moment for urine collection between first day urine, morning, afternoon and evening. Algorithms demonstrated that between 10 (for monobenzyl (MBzP) phthalate) and 31 (for bisphenol S) samples were necessary to correctly classify 87.5% of the subjects into quartiles according to their level of exposure. The results illustrate the high variability of urinary biomarkers of ED over time and the impossibility to reliably classify subjects based on a single urine sample (or a limited number). Results showed that classifying individuals based on urinary biomarkers requires several samples per subject, and this number is highly different for different biomarkers.

Can atmospheric pollutants influence menstrual cycle function?

A few experimental studies suggest that atmospheric pollutants could affect the endocrine system, and in particular stress hormones and the hypothalamic-hypophyseal-ovarian axis, which could in turn influence menstrual cycle function. We aimed to study the possible short-term effects of atmospheric pollutants on the length of the follicular and luteal phases and on the duration of the menstrual cycle in humans. To do so, from a nation-wide study on couples' fecundity, we recruited 184 women not using contraception who collected urine samples at least every other day during one menstrual cycle, from which a progesterone metabolite was assayed, allowing estimation of the duration of the follicular and luteal phases of the cycle. Atmospheric pollution (nitrogen dioxide and particulate matter with an aerodynamical diameter below 10 μm, PM₁₀) levels were estimated from a dispersion model with a 1-km resolution combined with permanent monitoring stations measurements, allowing to estimate exposures in the 30-day, 1-10 and 11-30-day periods before the start of the menstrual cycle. Regression models allowed to quantify the change in cycle duration associated with atmospheric pollutants and adjusted for potential confounders. Follicular phase duration increased on average by 0.7 day (95% confidence interval, CI, 0.2; 1.3) for each increase by 10 μg/m³ in NO₂ concentration averaged over the 30 days before the cycle and by 1.6 day (95% CI, 0.3; 2.9) for each increase by 10 μg/m³ in PM₁₀. There was no strong evidence of associations of exposures in this time window with luteal phase or with total menstrual cycle durations (p > 0.2). Exposures in the 1-10 day period before the cycle start were also associated with increased follicular phase duration. This study is one of the first prospective studies to suggest short-term alterations in follicular phase duration following atmospheric pollutants exposure.

Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome-free survival.

The Effect of Older Siblings on Language Development as a Function of Age Difference and Sex

The number of older siblings a child has is negatively correlated with the child’s verbal skills, perhaps because of competition for parents’ attention. In the current study, we examined the role of siblings’ sex and age gap as moderating factors, reasoning that they affect older siblings’ tendency to compensate for reduced parental attention. We hypothesized that children with an older sister have better language abilities than children with an older brother, especially when there is a large age gap between the two siblings. We reanalyzed data from the EDEN cohort ( N = 1,154) and found that children with an older sister had better language skills than those with an older brother. Contrary to predictions, results showed that the age gap between siblings was not associated with language skills and did not interact with sex. Results suggest that the negative effect of older siblings on language development may be entirely due to the role of older brothers. Our findings invite further research on the mechanisms involved in this effect.

Epigenetics as a mechanism linking developmental exposures to long-term toxicity

A variety of experimental and epidemiological studies lend support to the Developmental Origin of Health and Disease (DOHaD) concept. Yet, the actual mechanisms accounting for mid- and long-term effects of early-life exposures remain unclear. Epigenetic alterations such as changes in DNA methylation, histone modifications and the expression of certain RNAs have been suggested as possible mediators of long-term health effects of environmental stressors. This report captures discussions and conclusions debated during the last Prenatal Programming and Toxicity meeting held in Japan. Its first aim is to propose a number of criteria that are critical to support the primary contribution of epigenetics in DOHaD and intergenerational transmission of environmental stressors effects. The main criteria are the full characterization of the stressors, the actual window of exposure, the target tissue and function, the specificity of the epigenetic changes and the biological plausibility of the linkage between those changes and health outcomes. The second aim is to discuss long-term effects of a number of stressors such as smoking, air pollution and endocrine disruptors in order to identify the arguments supporting the involvement of an epigenetic mechanism. Based on the developed criteria, missing evidence and suggestions for future research will be identified. The third aim is to critically analyze the evidence supporting the involvement of epigenetic mechanisms in intergenerational and transgenerational effects of environmental exposure and to particularly discuss the role of placenta and sperm. While the article is not a systematic review and is not meant to be exhaustive, it critically assesses the contribution of epigenetics in the long-term effects of environmental exposures as well as provides insight for future research.

The independent role of prenatal and postnatal exposure to active and passive smoking on the development of early wheeze in children

Maternal smoking during pregnancy increases childhood asthma risk, but health effects in children of nonsmoking mothers passively exposed to tobacco smoke during pregnancy are unclear. We examined the association of maternal passive smoking during pregnancy and wheeze in children aged ≤2 years.Individual data of 27 993 mother-child pairs from 15 European birth cohorts were combined in pooled analyses taking into consideration potential confounders.Children with maternal exposure to passive smoking during pregnancy and no other smoking exposure were more likely to develop wheeze up to the age of 2 years (OR 1.11, 95% CI 1.03-1.20) compared with unexposed children. Risk of wheeze was further increased by children's postnatal passive smoke exposure in addition to their mothers' passive exposure during pregnancy (OR 1.29, 95% CI 1.19-1.40) and highest in children with both sources of passive exposure and mothers who smoked actively during pregnancy (OR 1.73, 95% CI 1.59-1.88). Risk of wheeze associated with tobacco smoke exposure was higher in children with an allergic versus nonallergic family history.Maternal passive smoking exposure during pregnancy is an independent risk factor for wheeze in children up to the age of 2 years. Pregnant females should avoid active and passive exposure to tobacco smoke for the benefit of their children's health.

120 MATERNAL EXPOSURE TO DIESEL ENGINE EXHAUST DURING PREGNANCY AFFECTS EARLY EMBRYO DEVELOPMENT IN A RABBIT MODEL

Airborne pollution has been associated with various adverse effects on human reproductive health, especially intrauterine growth retardation and early pregnancy loss. However, few studies have analysed its effect on early development. Diesel exhaust particles (DEP) have been shown to alter blastocyst formation when diluted in embryo culture medium (2010 Toxicol Sci. 117, 200–208), but no data are available concerning the effect of maternal inhalation of diesel exhaust on early embryo development. Our study has been designed to answer this question using rabbit as a model and DEP doses mimicking daily exposure to traffic in large European cities. New Zealand female rabbits were superovulated by means of 5 subcutaneous administration of pFSH for 3 days before mating, followed 10 to 12 h later by an intravenous administration of 30 IU of hCG at the time of mating (natural mating). Dams were exposed to a representative air pollution mixture; that is, diluted diesel engine exhaust (1 mg m–3; N = 14) or clean air (N = 12), for 1 h every morning and afternoon, from Day 3 to Day 6 post-coitum (dpc). At 6 dpc, in vivo-developed embryos were collected from uteri perfused with PBS and counted; their diameter was measured on pictures using ImageJ software (NIH, Bethesda, MD, USA). Another group of female rabbits was exposed to the same inhalation conditions from 3 to 27 dpc without superovulation treatment. Measures by ultrasound were performed on these dams at 7 dpc. Data were analysed by Mann-Whitney test and ANOVA, including dams as cofactor. At 6 dpc, number of embryos per dams was higher in exposed group compared with control (P < 0.05). In contrast, embryo diameter was significantly lower in the DEP exposed group compared with the clean air exposed group (P < 0.01). Gene expression analysis is being performed in these embryos. At 7 dpc, ultrasound measurements evidenced a decrease in embryo diameter, perimeter, and volume in the exposed group compared with control (P < 0.01, P < 0.01, and P < 0.01, respectively). These data indicate that repeated exposure to airborne pollution even for daily short periods affects early development. Consequences of maternal DEP exposure on feto-placental development are under investigation.

Cumulative incidence rate of medical consultation for fecundity problems--analysis of a prevalent cohort using competing risks

STUDY QUESTION

What is the incidence of medical consultation for fecundity problems in the French population, taking into account pregnancy occurrence and resumption of contraceptive use?.

SUMMARY ANSWER

Considering the occurrence of a pregnancy and resumption of use of contraception as competing risks, the cumulative incidence rate of medical consultation for fecundity problems was 9.0% [95% confidence interval (CI): 6.5%; 11.9%] after 12 months of unprotected intercourse and 12.2% [95% CI: 9.6%; 15.3%] after 24 months.

WHAT IS KNOWN ALREADY

Estimates of the prevalence of medical consultation due to involuntary infertility among couples who have sought a pregnancy for more than 12 months range from 25 to 50%. Most of the studies however are limited by retrospective data collection, without considering the duration of time since the beginning of the period of unprotected intercourse (PUI) and without considering medical consultation for fecundity problems as a competing risk.

STUDY DESIGN, SIZE, DURATION

This study is based on the Observatory of Fecundity in France survey, a population-based probability survey designed to estimate the frequency of involuntary infertility on a nationwide basis and to explore the associations with environmental factors. Women answered two telephone questionnaires, the first at the time of enrolment in 2007, the second at follow-up 1 year later. The current analysis was performed among a subsample of 6577 women recruited before or during a PUI and followed-up for 1 year.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study sample comprised 940 women aged 18-44 years who had a PUI between the time of enrolment and the 1-year follow-up, and who had not consulted a physician for fecundity problems for the current PUI prior to enrolment. Women reported all the medical consultations they had because of difficulties becoming pregnant during the current PUI. The date of each consultation was carefully assessed. In France, women can consult a gynaecologist directly without referral by their general practitioner. The occurrence of a pregnancy and resumption of contraceptive use were considered as informative censoring events, using a competing risk model.

MAIN RESULTS AND THE ROLE OF CHANCE

Using the competing risk survival model, the cumulative incidence rate of first consultation was 9.0% [95% CI: 6.5%; 11.9%] 12 months after the start of the PUI and 12.2% [95% CI: 9.6%; 15.3%] after 24 months. The Kaplan-Meier method, which does not take competing risks into account, yielded substantially higher estimates: 26.0% [95% CI: 18.8%; 32.5%] at 12 months and 56.8% [95% CI: 44.2%; 66.6%] at 24 months. Among the 219 women who had attempted to become pregnant for at least 12 months, cumulative incidences of first medical consultations were 28.2% [18.7-38.9%] 24 months after the start of the PUI, and 31.2% [21.3- 42.4%] after 36 months. The rates were higher among nulliparous but non-nulligravid women, followed by nulligravid women, as compared with parous women. Age was not strongly related to the occurrence of medical consultation.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study is the number of women lost to follow-up (29.7%). In addition, results regarding the absence of an age effect should be taken with caution as few women in our study were aged over 35 years. Although such an attrition rate is commonly observed in prospective studies in the general population, it could have induced a selection bias that may have led to an underestimation of the rates of medical consultation. Sensitivity analyses, using the inverse probability weighting method suggest that our results are unlikely to be biased.

WIDER IMPLICATIONS OF THE FINDINGS

This study reveals frequencies of medical consultation for fertility problems, which, after considering competing events such as pregnancy in a relevant statistical model, are lower than generally reported in the literature. The results also indicate the existence of a difference between the potential need and the actual use of medical care for fecundity problems. This suggests a need for studies to look for factors other than medical recommendations that may play a role in the patterns of medical seeking behaviours for fecundity problems, such as women's reproductive history, socio-economic characteristics or accessibility to infertility services.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by grants from ANR (French Agency for Research, SEST call on Environmental and Occupational Health), ANSES (French Agency for Food, environmental and Occupational Health Safety, EST call on Environmental and Occupational Health), InVS (French Institute for Public Health Surveillance). The team of Environmental Epidemiology applied to Fecundity and Reproduction has been funded by an AVENIR grant from Inserm (2007). Authors declare no conflict of interest.

Influence of fetal and parental factors on intrauterine growth measurements: results of the EDEN mother-child cohort

OBJECTIVE

In small-for-gestational-age neonates, parental and fetal characteristics can be used to distinguish between constitutionally small size and growth restriction, which is associated with a higher risk of morbidity and mortality. The aim of this study was to quantify relationships of parental and fetal characteristics with fetal ultrasound measurements.

METHODS

The EDEN mother-child cohort included 2002 pregnant women with singleton pregnancies attending one of two university hospitals. Data from two routine ultrasound examinations for fetal biometry were recorded, at 20-25 and 30-35 weeks of gestation. Biparietal diameter (BPD), head circumference (HC), femur length (FL), abdominal circumference (AC) and estimated fetal weight (EFW) were studied as a function of prepregnancy maternal body mass index (BMI), maternal height, paternal height, fetal sex and gestational age.

RESULTS

Data were obtained at the first scan from 1833 women and at the second scan from 1752 women. Parental anthropometric characteristics were significantly associated with ultrasound measurements at both scans. Maternal BMI was more strongly associated with AC and EFW, whereas both maternal and paternal height were more strongly associated with FL. An association was also found between fetal sex and all ultrasound measurements other than FL.

CONCLUSION

Maternal and paternal anthropometric characteristics are significantly associated with ultrasound measurements in mid to late pregnancy. These relationships provide support for the use of these characteristics in ultrasound fetal size reference charts.

[Evaluation of the deficiency and the submaximal exercise capacity in obstructive sleep apnoea patients]

BACKGROUND

In addition to excessive daytime somnolence, exercise limitation is a likely consequence of the cardiorespiratory problems that occur in patients who have obstructive sleep apnoea (OSA). However, few studies have evaluated the aerobic capacity of this patient group.

AIMS

To evaluate submaximal exercise capacity over the 6-minute walking test (6-MWT). To determine the factors that influence 6-minutes walking distance (6-MWD).

METHODS

INCLUSION CRITERIA

120 consecutive patients with severe OSA treated by continuous positive airway pressure who were medically stable will be included.

EXCLUSION CRITERIA

6-MWT contraindications, orthopaedic or rheumatologic diseases likely to influence walking capacity and corticosteroid therapy.

INVESTIGATIONS

polysomnography, electrocardiogram, plethysmography, and two 6-MWT's. Indicators of impaired exercise capacity: stops during the walk, 6-MWD less than or equal to predicted lower limit of normal, end walking dyspnoea greater than or equal to 5/10, oxygen saturation fall greater than or equal to five points, end walking heart rate less than or equal to 60 % maximal predicted. Data from our obese patients aged 40-60 years old will be compared with data from 45 age-matched obese subjects free from OSA.

EXPECTED RESULTS

OSA will significantly affect the submaximal exercise capacity and will accelerate the ageing of the cardiorespiratory-muscle chain. Submaximal exercise capacity of obese subjects having OSA, compared to subjects free from OSA, will be significantly deteriorated. 6-MWD of OSA patients will be significantly influenced by: resting plethysmographic data, apnoea hypopnoea index, arterial hypertension, obesity or smoking histories.

[Submaximal exercise capacity and quality of life in exclusive water-pipe smokers]

BACKGROUND

It is well known that oxidative stress is increased significantly by regular water-pipe smoking (WPS). This could lead to muscle dysfunction and thus to impairments of exercise and quality of life (QOL). Considering the impressive number of WP smokers, we intend to investigate the potential effect of WPS on submaximal exercise capacity and QOL.

AIMS

(1). To evaluate the submaximal exercise capacity by the 6-minutes walking test (6-MWT). (2). To compare the deficiency, incapacity and QOL data of exclusive WPS with those of two control groups (never smokers and exclusive cigarette smokers). (3). To determine the factors influencing the 6-minutes walk distance (6-MWD) of WPS subjects.

METHODS

A multicentre study including 180 exclusive WPS [> or =5 WP-year] men aged > or =40 years. Cigar or cigarette smoking, contraindications to the 6-MWT or cortico-steroid therapy will be exclusion criteria. QOL evaluation, spirometry, electrocardiogram and two 6-MWT will be performed. Signs of exercise impairment will be: 6-MWD< or =lower limit of normal, end of walk dyspnoea > or =5/10, haemoglobin saturation fall > or =5 points. Data from WPS subjects will be compared with those from 90 never smoking subjects and 90 exclusives cigarettes smokers.

EXPECTED RESULTS

(1). WPS will affect significantly the submaximal exercise capacity. (2). Resting spirometric, 6-MWT and QOL data of exclusive WPS subjects will be significantly reduced compared to never smoking subjects. (3). The 6-MWD's of exclusive WPS subjects will be significantly influenced by cumulative WP consumption, by resting spirometric data, by obesity and by physical activity score.

Nouvelles avancées dans l’étude de l’influence de l’environnement sur la santé reproductive masculine

BACKGROUND

An important part of the research effort on male reproductive health focus on two important questions: on the one side, that of the temporal deterioration of male reproductive health and, on the other head, that of the influence of exposure to environmental chemicals during intra-uterine life on health during childhood and adulthood. The concepts on endocrine disruption and testicular dysgenesis syndrome make a link between these two questions.

METHODS

This work examines knowledge cumulated over the last couple of years concerning geographical and temporal variations in male reproductive health and the testicular dysgenesis syndrome. Recent results concerning the concept of endocrine disruption and on the environmental influences on male reproduction are presented, as well as on the transgenerational effects on environmental factors on the health of male children.

CONCLUSIONS

Based on clinical and epidemiological data, and with the use of in vitro animal models as well as observations in wildlife, research in this field has enabled progress in the elucidation of mechanisms of action and characterization of environmental influences on male reproductive health.

Geographic variations in probability of pregnancy in four cities of France

BACKGROUND

Several studies have described geographic variations in human fecundability, but this phenomenon has almost exclusively been studied at an international level rather than within a given country. Our aim was to describe geographic variations in fecundability, the monthly probability of pregnancy, between four cities of France.

METHODS

We conducted a cross-sectional study in four French maternity units from Toulouse, Rennes, Lyons and Paris, among partners of pregnant women. Women were asked about the time to pregnancy (TTP) of their current pregnancy. TTP was analysed with a discrete Cox model allowing to estimate fecundability ratios (FR).

RESULTS

Time to pregnancy was defined for 894 couples. There was no strong evidence of heterogeneity in fecundability between the four compared cities (p=0.05 without adjustment and p=0.25 after adjustment for behavioural and medical factors). The highest fecundability was observed in Rennes and the lowest in Toulouse (fecundability ratio (FR)=1.28, 95% CI: 1.01-1.63). Differences in fecundability were smaller between the other cities.

CONCLUSION

We highlighted a possibly slightly higher fecundability in Rennes compared to Toulouse. Possible explanations for this finding are discussed. We note that the finding is consistent with previous observations indicating a higher sperm concentration among semen donors in Rennes than in Toulouse.

Controlling for continuous confounding factors: non- and semiparametric approaches

Confounding is one of the major types of bias encountered in observational epidemiologic surveys designed to study the relation between an exposure factor and a health event. A common way to remove confounding bias during the statistical analysis phase is to adjust for the confounders in a regression model. If a confounding factor is assessed as a continuous variable, it is necessary to define how the variable is entered into the regression model. In the case of logistic regression, we illustrate through simulation that coding by a binary variable or a categorical variable with broad categories may lead to substantial residual confounding. Specific approaches can be used to define a coding method that limits residual confounding. Among these, we briefly present nonparametric approaches and describe in detail several semiparametric approaches (generalised partial linear models, spline regression and fractional polynomials). These can be used to estimate the relation between a continuous factor and the health event of interest by a smooth non pre-specified function. In semiparametric models, the effect of certain covariates is coded by a parametric function, whereas the coding of one or two continuous variables is represented by a nonparametric function. These models can be used in exploratory analyses to describe dose-effect relations between the confounder and the health event, and thus help to define a relevant coding for the confounder.

Selection bias in semen studies due to self-selection of volunteers

BACKGROUND

Reports of a secular decrease in semen quality remain controversial, particularly due to the possibility of selection bias. We aimed to describe the potential bias due to self-selection of volunteers in semen studies involving fecund men.

METHODS

Using data from the French multicentre study REPRHOM, we compared the characteristics of the partners of pregnant women for three levels of participation: completion of a refusal questionnaire (n = 698), agreement to complete the study questionnaires only (n = 676) and agreement to complete the study questionnaires and give a semen sample (n = 331, 13% of the subjects approached).

RESULTS

Poorly educated men refused more often to participate than highly educated men. Semen providers were more likely to have experienced unfavourable pregnancy outcomes (odds ratio 1.68, 95% confidence interval 1.14-2.49) compared with participants completing the questionnaires only. Time to pregnancy was similar for all participants.

CONCLUSIONS

This study demonstrates the existence of selection bias in semen studies associated with fertility and socio-demographic characteristics of men. The results of semen analysis for this population sample cannot be extrapolated to the whole population from which the volunteers originate. More information is required on who participates, and participation rates should be reported in semen studies to make it possible to interpret the results correctly.

Epidemiology of male reproductive function: a field searching for tools

BACKGROUND

An increase in the frequency of disorders of the male human reproductive organs has been described over recent decades. Neither its causes nor its consequences on fecundity, the ability of the couples to produce a live child, are clearly known. This lack of knowledge may partly be due to methodological difficulties specific to reproductive epidemiology.

METHODS

We discuss the relevance and limits of some markers of the male aspects of human reproduction, focusing on semen parameters and fecundability, a measure of the probability of pregnancy.

RESULTS

Semen parameters are associated with fecundability, although they have a relatively low sensitivity to detect couples with low fecundability. The study of semen parameters proved central to describe the influence of environmental factors on the male side of reproductive function. The main limitation of semen studies is low participation rates and the possible selection biases ensuing. Fecundability can be estimated by collecting waiting time to pregnancy. Its assessment in retrospective studies often excludes the least fecund, those couples remaining childless, which entails a bias and a decrease in statistical power. The prospective approach and an approach relying on the enrollment of a cross-sectional sample of the couples currently trying to obtain a pregnancy (current duration approach) do not have these limitations. Although it has never been used, the assessment of fecundability using the current duration approach is promising both for aetiologic research and monitoring.

CONCLUSION

Most of the potential markers of male reproductive function are not assessed in the general population of France, with the exception of the incidence rate of testis cancer, which is currently increasing. We present some alternatives for a monitoring system of reproductive function.

[Use of national French health insurance register to identify the current address of a cohort]

BACKGROUND

The aim of the study was to assess the efficiency of the Registre National Inter-régimes des bénéficaires de l'Assurance-Maladie (RNIAM), which is the French register of health insurance, in order to identify the present address of subjects who have lived in the Beaumont-Hague county, France, between 1978 and 1998, when they were less than 25 years old.

METHODS

A cohort of 4,118 persons was defined by consulting school and civil status registers from three villages. We drew at random 824 subjects and between October 2000 and August 2001, we asked the RNIAM to locate them. For each subject, the usual identification parameters (first name, last name, birth date and eventually birth place) were provided. In case of a doubt concerning these parameters, a second request was undertaken with a slight modification.

RESULTS

Altogether, 94.5% of the included people were identified by the RNIAM. Identification was better for people born in France than for those born abroad (97% versus 52%) and 84.5% of people were linked to a health insurance regimen. The RNIAM was able to identify a correct address for 68.7% of the subjects.

CONCLUSION

The RNIAM seems promising for further epidemiological investigations. Nonetheless, it still remains insufficient by itself to identify addresses. Other means (tax records) should be evaluated and associated with the register data.

Population mixing and leukaemia in young people around the La Hague nuclear waste reprocessing plant

In order to investigate for an association between population mixing and the occurrence of leukaemia in young people (less than 25 years), a geographical study was conducted, for the years 1979 to 1998, in Nord Cotentin (France). This area experienced between the years 1978 and 1992 a major influx of workers for the construction of a nuclear power station and a new nuclear waste reprocessing unit. A population mixing index was defined on the basis of the number of workers born outside the French department of 'La Manche' and living in each 'commune', the basic geographical unit under study. The analyses were done with indirect standardisation and Poisson regression model allowing or not for extra-Poisson variation. Urban 'communes' were considered as the reference population. The Incidence Rate Ratio was 2.7 in rural 'communes' belonging to the highest tertile of population mixing (95% Bayesian credible interval, 95%BCI=1.2-5.9). A positive trend was observed among rural strata with increasing population mixing index (IRR for trend=1.4, 95%BCI=1.1-1.8). The risk became stronger for Acute Lymphoblastic Leukaemia in children 1-6 years old in the highest tertile of population mixing (IRR=5.5, 95%BCI=1.4-23.3). These findings provide further support for a possible infective basis of childhood leukaemia.

Time to pregnancy and semen parameters: a cross-sectional study among fertile couples from four European cities

BACKGROUND

In fertile populations, little is known about the association between semen parameters and time to pregnancy (TTP).

METHODS

Pregnant women from Copenhagen, Edinburgh, Paris and Turku who conceived without medical intervention were asked for their TTP (942 couples), and their partners provided a semen sample. The proportion of morphologically normal sperm and the multiple anomalies index (MAI, ratio of the total number of anomalies to the number of abnormal sperm) were centrally estimated. We estimated rate ratios for the occurrence of a pregnancy by a discrete survival model, adjusted for sexual activity and female factors affecting fecundity.

RESULTS

Increasing sperm concentration influenced TTP up to 55 x 10(6)/ml. The proportion of morphologically normal sperm influenced TTP up to 39% according to David's criteria, and this association held among the subjects with a sperm concentration >55 x 10(6)/ml. For strict criteria, the threshold value was 19% normal sperm. An increase of 0.5 in MAI was associated with an adjusted rate ratio for the occurrence of a pregnancy of 0.68 (95% confidence interval: 0.54-0.85).

CONCLUSIONS

These results highlight the importance of sperm morphology parameters and indicate that the effect of proportion of normal sperm on TTP may be independent of sperm concentration.

[Ionizing radiation and health: data and objectives]

Three dimensions must be considered to analyze the consequences of exposure to ionozing radiation on public health: assessment of exposure, measure of the public health risk, and monitoring the perception of risk by the population. We reviewed these three dimension for several situations of exposure to ionizing radiation: exposure related to the Chernobyl accident, occupational exposure, military-related exposure and medical exposure. For each situation, we discuss the pertinence of available data an monitoring systems used in France, and propose when necessary new systems. An extension of the cancer registries to the entire country would be a significant progress in terms of research and surveillance. This must be discussed in terms of potential utility in other domains of public health.

Regional differences in waiting time to pregnancy among fertile couples from four European cities

BACKGROUND

A previous European study found a longer time to pregnancy (TTP) among fertile women from Paris compared with women from other Western European countries. A co-ordinated, cross-sectional study of pregnant couples from Denmark (Copenhagen), France (Paris), Scotland (Edinburgh) and Finland (Turku) was therefore undertaken to assess differences in waiting TTP among couples from these cities.

METHODS

Pregnant women were invited to participate when they showed up for their first antenatal visit in one of the four centres. Inclusion criteria included that their partner was 20-45 years of age and born in the country in which he was currently living and that the pregnancy was achieved without fertility treatment. Both partners filled in a questionnaire and the man underwent a physical examination and delivered a semen sample (Turku: n = 237, Copenhagen: n = 302, Edinburgh: n = 212, Paris: n = 191).

RESULTS

French couples had a decreased probability of conception compared with couples from the other three countries, although only after adjustment for confounders. No significant differences between couples from the three other countries were found.

CONCLUSION

The observed geographical differences in TTP remain unexplained and were not due to differences in semen quality, but may be caused by varying exposures to environmental factors or psychological distress. In addition, selection bias due to the low participation rates cannot be ruled out. Future studies examining the causes for geographical differences in TTP are needed.

The incidence of childhood leukaemia around the La Hague nuclear waste reprocessing plant (France): a survey for the years 1978-1998

BACKGROUND

A previous study has suggested an increased incidence rate of leukaemia from 1978 to 1992 in people aged 0 to 24 years and living in the vicinity of the La Hague nuclear waste reprocessing plant without considering age and cytological type.

SETTING

The Nord Cotentin region (France) and the island of Alderney (United Kingdom).

STUDY OBJECTIVE

To describe the occurrence of leukaemia for each age group and cytological type from 1978 to 1998 in the same area, using accurate reference incidence rates and adequate estimation of the at risk population.

DESIGN

A geographical study of incidence using three zones defined according to their distance from the site (0 to 10 km: Beaumont-Hague electoral ward, 10 to 20 km and 20 to 35 km) has been conducted. The risk of leukaemia was estimated from the standardised incidence ratio (SIR) of the number of cases observed to the number expected. Exact 95% confidence intervals (CI) have been computed.

PARTICIPANTS

All people under the age of 25 years living in the study region between 1978 and 1998.

MAIN RESULTS

The observed number of cases of leukaemia in the study region as a whole was consistent with the expected value (SIR=1.03; 95%CI: 0.73, 1.41). No cases were observed on Alderney. The SIR in the Beaumont-Hague electoral ward was 2.17 (95%CI: 0.71, 5.07). The highest SIR was observed in the 5 to 9 years age group (SIR=6.38; 95%CI: 1.32, 18.65). This consists in acute lymphoblastic leukaemia cases.

CONCLUSION

This study indicates an increased incidence of leukaemia in the area situated at less than 10 km from the plant. Monitoring and further investigations should be targeted at acute lymphoblastic leukaemia occurring during the childhood incidence peak (before 10 years) in children living near the La Hague site and may be other nuclear reprocessing plants.

[Value of maximum expiratory volume per second and peak expiratory flow monitoring in asthma. 77 patients]

A retrospective study was conducted on a sample of 77 subjects to assess the interest of computerized flowmeter "one-flow" in the diagnosis and follow up of asthma. 77 patients and a control group matched for age and sex, measured four times by day, the forced expiratory volume in one second as well as the peak expiratory flow during 15 to 30 days. The monitoring of these two variables allowed to participate to the exclusion from the study of fifteen patients whose asthma diagnosis was informed. It also allowed the confirmation of four occupational asthma. Concerning the adherence of the treatment by patients, the conclusion of the study showed that 47% of patients modified their treatment at home without consulting their doctors, 38% resorted to their doctor and only 3% resorted to the emergencies.

[Medical treatment of atrial fibrillation in the healthy heart]

Whatever the cause and clinical features, establishing the strategy for the medical treatment of atrial fibrillation, requires three basic steps. First sinus rhythm must be restored, followed by the prescription of antiarrhythmic drugs to prevent recurrence and finally the use of anticoagulants. Obviously the underlying heart disease has a major effect on the patient's tolerance of atrial fibrillation, the risks of peripheral embolism and overall mortality. In patients with "solitary atrial fibrillation" and an apparently normal heart, each step of the treatment must be examined in light of the individual patients clinical situation and the risks of haemorrhage with anticoagulants as well as the risk of lethal ventricular arrhythmia due to the arrhythmogenic effect of class la or 1c antiarrhythmic drugs.

[Functional contribution of inhalation spacers in the treatment of asthma]

The aim of this study is to evaluate the ventilatory gain obtained by using metered dose inhaler (MDI) plus spacer versus MDI alone in 30 asthmatic patients (19 men and 11 women); aged 30 to 70 years old. Initial spirometry showed air flow obstruction. A reversibility test was performed with beta 2 agonists: first with MDI and then, later, with MDI plus spacer. In 27 cases (90%) the improvement of FEVI, referring to its initial value, was significantly better with spacer. This improvement was equal or superior to 20% in 19 patients with spacer versus only 9 patients with MDI. The improvement of FEVI was always better with spacer which ever the ways of expressing the bronchodilating response (referring to initial, predicted or absolute value). in conclusion, since the treatment of asthma is now based on local administration of medications, it is recommended to use spacers not only for children and patients who have coordination problems but more widely specially in severe asthma.

[Right accessory pathways with slow and decremential anterograde conduction. Electrophysiological changes during ablation of the proximal atrial poles]

Right sided accessory pathways with slow and decremential anterograde conduction differ from the anatomical substrates of the nodo-ventricular connections described by Mahaim. The connection may also be atrio-ventricular or atrio-fascicular. The authors report a series of 6 patients (2 men, average age 31 +/- 9 years) with antidromic reciprocating tachycardia implicating accessory pathways with decremential conduction (wide QRS complexes with left bundle branch block) the radiofrequency ablation of which was centered on the proximal atrial pole. The increment of pre-excitation was 75 +/- 18 ms. No nodo-ventricular or nodo-fascicular connections were observed. One patient had an atrio-ventricular connection, the mapping and ablation (5 applications) of which were performed on the annulus, as if it were a bundle of Kent. Five patients had a nodo-fascicular connection which was masked during sinus rhythm. The localisation of the proximal atrial insertion on the tricuspid annulus was initially estimated by studying the superior junction of the circuit and by endocavitary stimulation, and then by recording the M potential (activation of the accessory pathway). This was recorded in 4 patients, either at a specific point on the annulus (lateral or postero-lateral) which was the target of ablation (3 patients, 5 +/- 3 applications) or over a wider region (2 cm) at which ablation failed (1 patient: 13 applications). The site of the increment was determined in 2 patients and was proximal to the M potential. The M potential could not be recorded on the annulus in one patient. In 2 patients, the M potential was also recorded along the side of the pathway on the antero-lateral wall of the right ventricle of the tricuspid valve at its distal pole. In 2 patients, ablation was centered on the distal pole in second intention, near to the terminal part of the right bundle where it was localised in one of the two (18 applications). Finally, ablation was obtained in 5 out of 6 patients. They remain asymptomatic after 12 +/- 7 months follow-up. These cases show that accessory pathways with slow decremential conduction usually behave like a complete conduction pathway with an accessory laterally situated atrioventricular node on the tricuspid, an accessory bundle and a distal insertion which are all accessible to ablation.

[Catheter ablation of atrioventricular nodal reentrant tachycardia]

Electrophysiological data of atrioventricular nodal reentrant tachycardia recensed over the last 40 years in the animal and in man has not resolved the question as to the exact site of the reentry circuit: an exclusively intranodal pathway or a pathway involving part of the atrium? The remarkable efficacy of modern radical therapy of this arrhythmia with preservation of atrioventricular conduction reinforces the concept of reentry involving not only the atrioventricular node but also the juxta nodal atrium and the superior and inferior atrionodal connections. Radical treatment was initially surgical and then by catheter ablation. The technique of specific ablation of the rapid anterior pathway was the first to be described. Its limitation is the relatively high risk (about 10%) of complete atrioventricular block. Very quickly, radiofrequency ablation of the slow posterior pathway became the method of reference. Most patients do not have retrograde conduction in the slow pathway. The pathway is located in sinus rhythm by recording its specific potentials: either the rapid potential described by Jackman et al or the fragmented potential described by Haïssaguerre and Warin. The former is recorded from the posterior septal position anterior to the orifice of the coronary sinus; the second is recorded at the same level but slightly above in the mid septal position. Ablation of the slow pathway can be performed on these purely anatomical criteria. Using these approaches, an immediate success rate of over 90% may be obtained. The recurrence rate is 0 to 5%; that of complete atrioventricular block ranges from 0 to 4%.(ABSTRACT TRUNCATED AT 250 WORDS)

[Automatic implantable defibrillators: long-term results]

The automatic implantable defibrillator is an essential component of the preventive management of sudden death of patients with malignant ventricular arrhythmias. Though its efficacy in this indication is not contested, the data concerning its influence on global cardiac mortality is more controversial. The elements of this controversy are reviewed. Several prognostic factors are implicated, the principal of which being the patient's haemodynamic status as assessed by objective evaluation of left ventricular function. Prospective randomised studies comparing medical therapy with the automatic implantable defibrillator are under way and should provide a better understanding of its indications in the future.