Maternal occupational exposures to nanoscale particles and small for gestational age outcome in the French Longitudinal Study of Children.

OBJECTIVES: To investigate the association between maternal occupational exposures to nanoscale particles (NPs) during pregnancy and small for gestational age (SGA). METHODS: This study included 11,224 mothers and singleton birth pairs from the French Longitudinal Study of Children (ELFE cohort), which included infants born after 33 weeks of gestation or more in continental France in 2011. Mothers who did not work during pregnancy were excluded from the analyses. Maternal occupational exposures to NPs was estimated using a job-exposure matrix for the probability (>50%: occupationally exposed group, n = 569; 0%: occupationally non-exposed group, n = 9113; between these two thresholds: uncertain group, n = 1542) and frequency of exposure. Associations were estimated from multivariate logistic regression models for occupationally exposed vs occupationally unexposed groups in a first analysis, and with the frequency-weighted duration of work for the occupationally exposed group only in a second analysis. RESULTS: Among working mothers, 5.1% were occupationally exposed to NPs. Maternal occupational exposures to NPs was associated with SGA (ORa = 1.63, 95% CI: 1.22, 2.18). The frequency-weighted duration of work for the occupationally exposed group (n = 569) was not associated with SGA (ORa = 1.02, 95% CI: 0.97, 1.08) in adjusted analyses. CONCLUSIONS: These results, showing a significant association between occupational exposures to NPs and SGA, should encourage further studies to examine the adverse effect of NPs exposure on fetal development.

Maternal cumulative exposure to extremely low frequency electromagnetic fields and pregnancy outcomes in the Elfe cohort.

OBJECTIVES: To study the relations between maternal cumulative exposure to extremely low frequency electromagnetic fields (ELF EMF) and the risk of moderate prematurity and small for gestational age within the Elfe cohort. METHODS: The Elfe study included 18,329 infants born at 33weeks of gestation or more in France in 2011 and was designed to follow the children until 20years of age. Gestational age and anthropometric data at birth were collected in medical records and small for gestational age was defined according to a French customized growth standard. During interviews, mothers were asked to report their job status during pregnancy. If employed, their occupation was coded according to the International Standard Classification of Occupations 1988 and the date on which they stopped their work was recorded. Cumulative exposure to ELF EMF during pregnancy was assessed, for both mothers who worked and those who did not during pregnancy, using a recently-updated job-exposure matrix (JEM). Cumulative exposure was considered as a categorical variable (<17.5, 17.5-23.8, 23.8-36.2, 36.2-61.6 or ≥61.6µT-days), a binary variable (<44.1 and ≥44.1µT-days) and a continuous variable. Associations were analyzed by logistic regression, adjusting for the mother's lifestyle factors, sociodemographic characteristics and some mother's medical history during and before pregnancy. Analyses were restricted to single births and to complete values for the pregnancy outcomes (n=16,733). RESULTS: Cumulative exposure was obtained for 96.0% of the mothers. Among them, 37.5% were classified in the 23.8-36.2µT-days category, but high exposures were rare: 1.3% in the ≥61.6µT-days category and 5.5% in the ≥44.1µT-days category. No significant association was observed between maternal cumulative exposure and moderate prematurity and small for gestational age in this exposure range. CONCLUSION: This large population-based study does not suggest that maternal exposure to ELF EMF during pregnancy is highly associated with risks of moderate prematurity or small for gestational age.

[Occupational risk factors for lung cancer]. / Facteurs de risque professionnels du cancer bronchopulmonaire.

OBJECTIVE: We aimed to review the literature regarding the dose-response relationship between occupational exposure to chemicals classified by the International Agency for Research on Cancer (IARC) as carcinogenic agents and the risk of some lung cancers and on any combined effect with tobacco exposure on lung cancer risk. METHODS: A literature search was performed in three databases as well as in the IARC monographs between January 1990 and April 2015. RESULTS: The literature is abundant for some carcinogens such as asbestos, crystalline silica and diesel exhaust fumes but is more sparse for many carcinogens and particularly any interaction with tobacco on lung cancer risk. CONCLUSION: Few data exist for most lung occupational carcinogens including their interaction with tobacco exposure. In the case of exposure to occupational carcinogens and co-exposure to tobacco smoke, there is a dual primary prevention objective: the elimination of both occupational risk factors and tobacco smoke.

Occupational and non-occupational attributable risk of asbestos exposure for malignant pleural mesothelioma.

OBJECTIVES: To estimate the proportion of pleural mesothelioma cases that can be attributed to asbestos exposure in France including non-occupational exposure. METHODS: A population-based case-control study including 437 incident cases and 874 controls was conducted from 1998 to 2002. Occupational and non-occupational asbestos exposure was assessed retrospectively by two expert hygienists. ORs of pleural mesothelioma for asbestos-exposed subjects compared to non-exposed subjects, and population-attributable risk (ARp) of asbestos exposure were estimated using a conditional logistic regression. RESULTS: A clear dose-response relationship was observed between occupational asbestos exposure and pleural mesothelioma (OR=4.0 (99% CI 1.9 to 8.3) for men exposed at less than 0.1 f/mL-year vs. 67.0 (99% CI 25.6 to 175.1) for men exposed at more than 10 f/mL-year). The occupational asbestos ARp was 83.1% (99% CI 74.5% to 91.7%) for men and 41.7% (99% CI 25.3% to 58.0%) for women. A higher risk of pleural mesothelioma was observed in subjects non-occupationally exposed to asbestos compared to those never exposed. The non-occupational asbestos ARp for these subjects was 20.0% (99% CI -33.5% to 73.5%) in men and 38.7% (99% CI 8.4% to 69.0%) in women. When considering all kinds of asbestos exposure, ARp was 87.3% (99% CI 78.9% to 95.7%) for men and 64.8% (99% CI 45.4% to 84.3%) for women. CONCLUSIONS: Our study suggests that the overall ARp in women is largely driven by non-occupational asbestos exposure arguing for the strong impact of such exposure in pleural mesothelioma occurrence. Considering the difficulty in assessing domestic or environmental asbestos exposure, this could explain the observed difference in ARp between men and women.

[Growing incidence of nalidixic acid resistance and sensitivity to quinolones in Salmonella typhimurium strains isolated from man or animal]. / Incidence croissante de la résistance à l'acide nalidixique et sensibilité aux quinolones des souches de Salmonella typhimurium isolées chez l'homme ou l'animal.

To determine the prevalence of quinolone resistance in Salmonella typhimurium strains from humans or animals (cattle, poultry, swine), the S. typhimurium strains isolated at a teaching hospital and at the central veterinary laboratory of the same district between January 1, 1995, and December 31, 1996 were studied. Susceptibility to nalidixic acid was determined using the disk diffusion method. Strains with decreased susceptibility to nalidixic acid were subjected to minimal inhibitory concentration (MIC) determination for pefloxacin, ofloxacin, ciprofloxacin, norfloxacin, levofloxacin, and grepafloxacin. Decreased susceptibility to nalidixic acid was demonstrated for 41 of the 309 strains studied and increased from 8.5% in 1995 to 18.6% in 1996. MIC90 values of fluoroquinolones for strains with decreased susceptibility to nalidixic acid were lower than 1 mg/L, which is the cutoff above which a strain is classified as susceptible, but were higher than for strains that were susceptible to nalidixic acid. These low levels of resistance may be the first step in selection of mutant strains with high levels of resistance to fluoroquinolones. This warrants continued monitoring of resistance of Salmonella to fluoroquinolones.

Use of superfused rat skeletal muscle for metabolic studies: assessment of pH by 31P n.m.r.

We developed a muscle superfusion system suitable for metabolic studies of small isolated rat muscle ex vivo in real time and in a non-destructive manner by n.m.r. spectroscopy. In order to determine biochemical stability of superfused extensor digitorum longus (EDL) muscle (from fasted 45 and 100 g rats), the energy state and the pH of muscle were continuously monitored by 31P n.m.r. spectroscopy. ATP and phosphocreatine remained stable during 2 h whatever the muscle size (20 or 45 mg). Neither metabolite was a sensitive probe of possible metabolic compartmentation within muscle under our experimental conditions. By contrast, the chemical shift of Pi by its sensitivity to pH was a discriminant factor in the assessment of muscle stability. Indeed, heterogeneity of pH was observed only in the 45 mg EDL muscle resulting from a core region with loss of glycogen. Together, these observations suggest deviations of energy metabolism to supply ATP. Consequently, pH may be considered as a new real-time criterion for monitoring a metabolic heterogeneity due to changes in energy metabolism of muscle preparations ex vivo.

Muscle differentiation in the bovine fetus: a histological and histochemical approach.

The chronology of muscle fiber differentiation was analysed in 37 fetal calves of 69 to 266 days of age. Semitendinosus muscle weight was measured throughout the experimental period and biochemical, histological and histochemical investigations were made to determine respectively the protein and DNA content of the muscle, the size and the number of the fibers and their ATPase and SDH activity. The relative growth of all the quantitative characteristics (muscle weight, protein and DNA content) was much greater in the early stages of gestation than in the new-born animal. In the younger fetuses DNA relative growth was faster than protein relative growth, whereas at the end of gestation the reverse progression was observed. Before 90 days, the muscle tissue was composed of myotube-like cells without any clear organization. The organization of muscle tissue into clear bundles occurred around 120 days of age, and about 30 days later the large myotubes transformed into myofibers. The myotubes reacted positively for acid-ATPase activity, whereas the large population of smaller cells which developed in parallel did not. The number of muscle cells increased up to 240 days of age, as did the percentage of fibers positive for acid-ATPase activity. Finally, oxidative differentiation occurred around 260 days of age, with the appearance of a population of cells characterized by increased SDH activity. A comparison of these results with previous findings suggests that the muscular tissue differentiates through similar stages in various species, but over different lengths of time. The percentage of mature weight might provide a better inter-species time scale than chronological age.

New multiplexing technique using polarization of light.

A new scheme for coding optical signals using the polarization of light is described. The coding response is shown to be linear and invariant. As a consequence of the vectorial nature of the electromagnetic waves, this response takes a sinusoidal shape, which limits the number of channels to three. An application to fiber optics transmissions is presented; an experimental 50-m link is described. The performance and loss of the system are discussed as well as the influence of specific factors, such as the coherence length of the source and the random mode-coupling. As a conclusion, the compatibility of this new multiplexing principle with other multiplexing methods is examined.

Usefulness of various biochemical and histochemical characteristics as indices of muscle type in lamb carcasses.

Contractile and metabolic characteristics of five different muscles from an homogeneous group of seven lambs were studied. Muscle typing was assessed by measuring myofibrillar ATPase and lactate deshydrogenase activities, myosin (FM1, FM2, FM3, SM1, SM2) and LDH (M(4), M(3)H, M(2)H(2), MH(3), H(4)) isoforms levels as well as fibre types composition (SO, SOG, FOG, FG). On this basis, muscles were classified as slow-twitch oxidative (diaphragm and supraspinatus), intermediate (triceps brachii), fast-twitch oxidative-glycolytic (longissimus dorsi) and fast-twitch glycolytic (tensor fascia latae). Discriminant factor analysis of data revealed that variables enabling a better discrimination of muscles (FG, SM1, FM2, FM1, H(4)) exhibited the lowest efficiency to discrimate animals. Furthermore, in contrast to LDH isoforms and fibre type composition subsets of variables, myosin isoforms analysis allowed a quite total identification of muscle classes since, 97·5% of the muscles were well ranged in their respective classes. Although animals were zootechnically similar, animal variability was important and animal effect was essentially detected through changes in the following set of variables: M(3)H, MH(3), SO and ATPase.

Glycogen depletion patterns in myofibres of cattle during stress.

The response of the three major types of fibre in beef M. longissimus dorsi during stress and recovery was examined with respect to cellular glycogen content. Two different forms of stress were induced in Friesian bulls, by mixing with strangers for a 5h period or by subcutaneous injections of adrenaline. Muscle biopsy samples were taken during stress and recovery for biochemical and histochemical analysis of glycogen content. Muscle glycogen concentration fell to 45% of the resting value during mixing stress and to 37% of the resting value after adrenaline treatment. Slow-twitch and fast-twitch fibre types responded differently to stress, and the differences were reversed in the two forms of stress studied. Mixing stress caused a greater loss of glycogen from the two fast fibre types than from the slow type while adrenaline caused a much greater loss of glycogen from the slow fibres than from the two fast fibre types. The results demonstrate that glycogen is selectively depleted in muscle fibres in response to stress and that the pattern of depletion is different in adrenaline versus mixing stress.

Space and time variables in optics and holography: recent experimental aspects.

Assuming some parallelism between space and time variables, namely, in the frequency domain, that occurs in the description of optical signals as functions of space or/and space and time, the Abbe theory applies to temporal distributions. The concept of temporal response of any optical system, space invariant, working at the time frequency nu = c/lambda, is then brought out. A method of temporal encoding of optical information is also reported, leading to a consideration of the output of spectroscopic devices as a Temporal Fourier Hologram (TFH). This applies to metrology (interferometry in white light, surface testing, roughness measurements) and image processing by temporal holography. Holograms of extended self-luminous objects have been recorded in white light, and reconstructed images are presented.