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Biomedical subjects

P Wild

Publications and source records attributed to P Wild.

At least 55 records · Page 3Linked to original sources
PubMed1997

Comparative reproduction of Cryptosporidium baileyi in embryonated eggs and in chickens.

At 2 days of age, each of 20 chickens was perorally or intracloacally infected with 3 x 10(5) oocysts of Cryptosporidium baileyi and maintained for 13 days post infection. In parallel, 20 embryonated chicken eggs were inoculated with 3 x 10(5) oocysts at day 10 of embryonation and were incubated for a further 7 days. The average reproduction rates in the two groups of chickens were x560 after peroral infection and x533 after intracloacal infection as compared with x256 in the eggs. Although the rate of reproduction of parasites seen in the eggs was only about 50% of that observed in chickens, large numbers of oocysts could be harvested (on average, 77 million per egg versus 161 and 168 million from chickens). Nearly the same number of oocysts could be obtained from two eggs as compared with one chicken. The use of embryonated eggs accommodates the sense of animal-protection regulations, is less expensive, and allows the isolation of oocysts under sterile conditions.

Animals↗
PubMed1997

[Development of a job-exposure matrix in the heavy-metal industry in France].

A job exposure matrix (JEM) was developed by a committee of experts using the DELPHI method, in the French hard metal industry, in order to assess occupational exposures to cobalt along with tungsten carbide resulting from the industrial process. This JEM is part of a nested case-control study, carried out within the historical cohort of workers ever employed in these factories, aimed at assessing lung cancer risk. The committee included 8 experts: hygienists, chemical engineers, occupational physicians and epidemiologists. The JEM was developed in four stages: (i) visit of factories, (ii) definition of lines (job-periods) and columns (exposures) of the JEM, (iii) definition of coding procedures, (iv) coding the cells of the JEM. This last stage used a method derived from the DELPHI method. Throughout the study period 1945-1994. 320 job-periods and 21 agents were defined. A quantitative assignment (level 0 to level 9) along with a frequency code (1 to 3) was attempted for 4 agents, whereas only a qualitative assignment (non exposed/exposed, i.e. 0/l) was done for the other agents. An additional probability code (1 to 3) was assigned to all agents. This procedure led to 46 columns and 14,720 cells in the JEM. When applying the DELPHI method, the consensus of the committee was obtained for 85% of all cells after the first individual assignment of experts, 88% after the second individual assignment and 100% after the third assignment by the experts all together. In order to validate the JEM, these expert assignments will be brought together with the results of exposure measurements that were performed in some workplaces of these factories. The JEM will also be linked with the data base of the case-control study for the exposure assessment of cases and controls.

Case-Control Studies↗
PubMed1996

Characterization of F18 fimbrial genes fedE and fedF involved in adhesion and length of enterotoxemic Escherichia coli strain 107/86.

Infection of susceptible weaned pigs with oedema disease strains of E. coli is associated with bacterial adhesion to the small intestine. F18 fimbria (previously named F107) was the first colonisation factor described on oedema disease strains, and its genetic determinant was cloned. In the present study, genes fedE and fedF were positioned in the F18 gene cluster, downstream of the major structural subunit gene fedA. Two fedE and two fedF mutants were identified that had lost their capacity to adhere to isolated porcine villi. Moreover, these mutants produced significantly longer fimbriae. In vitro adhesion tests, electron microscopy study, transcomplementation tests, and nucleotide sequence analysis indicated that proteins FedE and FedF are F18 minor subunits essential for fimbrial adhesion and effecting fimbrial length.

Bacterial Adhesion↗
PubMed1996

Airflow obstruction in chalkpowder and sugar workers.

Our aim was to investigate the relationship between suspected occupational hazards and airflow obstruction in industrial workers. The study was a cross-sectional survey of 314 male workers from a chalkpowder plant (n = 158) and from a sugar refinery (n = 156). Occupational exposure to chalkpowder and sugar dust was assessed by individual job classification. Outcome variables included respiratory symptoms and routine spirometric parameters. Statistical analysis was done for each industry separately. Overall, mean pulmonary function parameters fell either within or above the normal range in both industries. However, analysis by job classification showed that in the chalkpowder plant, all indices of airway obstruction declined significantly with increasing dustiness. Additionally, workers in the dustiest workplace (chalk sacking) had significantly lower airflow parameters than workers from other workstations. In the sugar refinery, workers exposed to sugar dust in the sugar cube manufacture workstation had significantly lower forced expiratory volume in 1 s (FEV1) (p = 0.02) than the non-exposed ones. For both industries, the proportion of subjects complaining of cough and/or phlegm was greater among the most exposed subgroups than among the remaining workers but the differences were not statistically significant. In conclusion, coupling spirometry to job classification proved useful in disclosing a relationship between airflow obstruction and exposure to either chalkpowder or sugar dust in industrial workers.

Adult↗
PubMed1996

Helper virus-free transfer of herpes simplex virus type 1 plasmid vectors into neural cells.

Herpes simplex virus type 1 (HSV-1) plasmid vectors have promise for genetic intervention in the brain, but several problems caused by the helper virus have compromised their utility. To develop a helper virus-free packaging system for these vectors, the DNA cleavage/packaging signals were deleted from a set of cosmids that represents the HSV-1 genome. Following cotransfection into cells, this modified cosmid set supported replication and packaging of vector DNA. However, in the absence of the DNA cleavage/packaging signals, the HSV-1 genome was not packaged, and consequently vector stocks were free of detectable helper virus. In the absence of helper virus, the vectors efficiently infected rat neural cells in culture or in the brain with minimal cytopathic effects. beta-galactosidase-positive cells were observed for at least 1 month in vivo, and vector DNA persisted for this period. This system may facilitate studies on neuronal physiology and potential therapeutic applications.

Animals↗
PubMed1996

Airway responsiveness, respiratory symptoms, and exposures to soluble oil mist in mechanical workers.

OBJECTIVES: To assess the relation between measured levels of exposure to soluble oil mists in a plant manufacturing ball bearings, and both respiratory symptoms and airway responsiveness in the workforce. METHODS: 114 male workers exposed to oil mist and 55 unexposed male controls from nearby factories were studied. Soluble oil mist concentrations were measured with area samplers. Respiratory symptoms were assessed by questionnaire and measurement of airway responsiveness to methacholine with an abbreviated method. Subjects were labelled positive to methacholine airway challenge (MAC+) if forced expiratory volume in one second (FEV1) fell by > or = 20%. The linear dose-response slope was calculated as the percentage fall in FEV1 at the last dose divided by the total dose given. RESULTS: Geometric mean concentrations of oil mists ranged from 0.65 mg/m3 (GSD 1.29) to 2.20 mg/m3 (GSD 1.55) based on 92 measurements obtained from 1979-93. The prevalence of chronic cough or phlegm, bouts of bronchitis, and dyspnoea was greater among exposed workers than among controls (odds ratio (OR) 4.64, P = 0.002 for chronic cough and phlegm). After adjustment for smoking and age, dyspnoea was significantly related to an index of cumulative exposure to oil mist (OR 1.44, P = 0.006/10 y.mg/m3). The proportion of MAC+ subjects was similar in the two groups. However, after adjustment for baseline FEV1 and age, the dose-response slope was significantly steeper among exposed workers than among controls (P = 0.01), a finding indicating airway hyperresponsiveness in the exposed workers. Furthermore, the dose-response slope was significantly related to baseline FEV1, age, and, after adjustment for FEV1, the index of cumulative exposure to oil (P = 0.004). CONCLUSION: Subjects with exposure to soluble oil mist in the metal industry are at risk of developing both respiratory symptoms and airway hyperresponsiveness.

Aerosols↗
PubMed1995

Mammalian parathyroids: morphological and functional implications.

Fixation with aldehydes is achieved either by immersion or perfusion. The parenchyma of parathyroid glands fixed by immersion consists of dark cells containing a lot of membranes of these organelles which are concerned with hormone secretion, light cells which are poor in these organelles, intermediate forms between the two, and multinuclear syncytial cells. They have been attributed to represent different functional stages of secretory activity, the dark cell being in an active form, the light cell in a resting form. Studies of the parathyroids of mice, rats, rabbits, cats, dogs, pigs, cattle, sheep, goats, and horses employing various fixation protocols clearly demonstrate that light cell variants and multinuclear syncytial cells are formed during improper immersion fixation as a result of membrane disintegration. Parathyroids fixed by perfusion or by immersion in an appropriate fixation medium comprise only one cell type which correspond to the dark chief cell. Parathyroid cells are polar cells bearing some of the rough endoplasmic reticulum in the basal pole, the rest of it, the Golgi complex, and secretory granules in the apical pole. The secretory product is released by exocytosis at the apicolateral domain of the plasma membrane into the intercellular space. Secretory activity can be altered experimentally, leading to drastic changes in the amount of cell membrane related to hormone synthesis, intracellular transport, exocytic release, and secretion coupled membrane retrieval. The sensitive reaction of parathyroid cells to both the mode of fixation and to fixation media demands careful evaluation of the fixation protocol. This and the polarity of parathyroid cells have to be borne in mind for estimating secretory activity on the basis of morphological criteria.

Animals↗
PubMed1995

The biological significance of storage granules in rat parathyroid cells.

Both prosecretory and storage granules are concomitantly formed at the trans Golgi network including the innermost Golgi cisterna. Prosecretory granules develop into small secretory granules that release their contents by exocytosis finely regulated by a complex mechanism for maintaining calcium homeostasis. In the rat parathyroid cells, storage granules are large secretory granules storing parathyroid hormone for an emergency supply. The hormone is rapidly discharged by exocytosis when serum calcium concentration is decreased. The granules are constantly produced even under conditions of low serum calcium concentration in the regions of 8 mg/dl. The granule content is constantly hydrolyzed when not discharged, leading to a decreased core and finally to the formation of vacuolar bodies. The fate of the vacuolar bodies is unknown. Hypercalcemic conditions accelerate hydrolysis. The threshold value of calcium concentration required for the release of storage granule contents is between 8.0 and 7.5 mg/dl and that of calcium concentration for accelerating degradation of storage granules is about 11.5 mg/dl. Sympathetic stimulation causes storage granules to be discharged regardless of hypercalcemia or hypocalcemia. Parasympathetic stimulation accelerates hydrolysis. The degradation of storage granules seems to be closely associated with an intracellular regulatory mechanism for parathyroid hormone secretion.

Adrenergic beta-Agonists↗
PubMed1995

Respiratory symptoms, ventilatory impairment, and bronchial reactivity in oil mist-exposed automobile workers.

Studies concerning the respiratory effects of oil mists are sparse and contradictory. The aim of this study was to determine the respective effects of occupational exposure to straight cutting oils and soluble mineral oils on the prevalence of respiratory symptoms, ventilatory impairment, and bronchial reactivity. The population study consisted of 308 male workers of a large French car-making plant, including 40 subjects chronically exposed to straight cutting oils (group S), 51 subjects chronically exposed to soluble mineral oils (group E), 139 subjects with chronic dual exposure to straight cutting oils and soluble mineral oils (group D), and 78 unexposed assembly workers used as a control group (group C). Worker evaluation included a standardized questionnaire, measurement of pulmonary function, and a methacholine challenge. Oil mist concentration at the work place was determined by gravimetric analysis. The arithmetic mean concentration was 2.6 +/- 1.8 mg/m3. The geometric mean concentration was 2.2 +/- 1.9 mg/m3. The prevalence of respiratory symptoms did not differ significantly among the four groups. However, the subjects exposed to straight cutting oils (group S + group D) had a significantly higher prevalence of chronic cough and/or phlegm than the others (group E + group O): 25.7% vs. 16.3% (p = 0.048). Furthermore, the prevalence of cough and/or phlegm increased significantly (p = 0.03) with increasing duration of exposure to straight cutting oils after adjustment on smoking categories. Lung function tests did not differ significantly among the four groups but we observed a significant decrease of forced expiratory volume in 1 sec (FEV1), forced expiratory flow during the middle half of forced vital capacity (FEF25-75), and maximal flow rate at 50% and 25% of exhaled forced vital capacity (V50 and V25) according to duration of exposure among smokers exposed to straight cutting oils, suggesting a synergistic effect of tobacco and insoluble oils. No effect of exposure to mineral oils on bronchial reactivity was demonstrated. It is concluded that despite low levels of pollution by oil mists, the present study has shown tenuous adverse chronic effects of straight cutting oils on respiratory symptoms and lung function. However, no adverse effect of soluble mineral oils was demonstrated. These results suggest that threshold limit values for mineral oils should be reassessed.

Adult↗
PubMed1995

Airway responsiveness to methacholine, respiratory symptoms, and dust exposure levels in grain and flour mill workers in eastern France.

Our goal was to assess the relation between dust exposure levels and the respiratory health status of workers in grain and flour mills in eastern France. We studied 118 male workers from 11 mills and 164 unexposed male controls. Dust concentration was measured by personal sampling methods. Outcome variables included respiratory symptoms, routine pulmonary function tests, and indices of airway responsiveness to methacholine. A great within- and between-area variability of inhalable dust concentration was found in all mills. A dose-response relationship was observed between dust exposure levels and chronic respiratory symptoms, suggesting that exposure to grain and flour dust may lead to chronic bronchitis. A significant relation was found between dust exposure and airway hyper-responsiveness; this finding is important since it has been hypothesized that the latter abnormality may lead to or be a predisposing factor in subsequent chronic, irreversible airflow obstruction.

Adult↗
PubMed1995

Altered partition of T cell subsets in the peripheral blood of healthy workers exposed to flour dust.

Occupational exposure to organic compounds can induce obvious immunological disorders or more subtle modifications. We investigated peripheral blood lymphocyte subsets in 34 bakers and 82 millers exposed to wheat flour dust, and 51 salt factory workers. Significantly decreased levels of CD4+, CD8+, CD57+ and CD8+/57+ cells were noted in mill workers, and of CD57+ cells in bakers. CD29+ and CD4+/CD29+ cells were significantly lower in millers, CD4+/CD45RA+ cells higher in all exposed workers. The lower numbers of positive cells noted in millers appeared associated to significantly higher (p < 0.001) levels of CD29 and CD45RA expression as measured by fluorescence intensity. These data are opposite to those previously reported in asthmatic workers exposed to flour dust. Since the individuals tested here were clinically healthy, the alterations of T-cell subsets observed could be interpreted as a successful attempt at immunoregulation maintaining homeostasis.

Antigens, CD↗
PubMed1995

Mortality study among workers producing chromate pigments in France.

In a follow-up study of 294 men who had worked for at least 6 months in a chromate-producing factory in France between 1958 and 1987, only 16 were lost to follow-up and the number of person-years in the study was 5207. Occupational data were provided by the administration of the plant. The causes of deaths were ascertained from hospital and general practitioners' records. The observed numbers of deaths were compared with the expected numbers based on local rates with adjustment for age, sex and calendar time (standardized mortality ratio, SMR). The overall mortality did not differ significantly from that expected (SMR = 1.20, 95% CI = 0.98-1.47), whereas mortality due to lung cancer was in significant excess (SMR = 3.60, 95% CI = 2.13-5.68). Significantly higher lung cancer SMRs were found for workers whose duration of employment was more than 10 years. A non-significant excess was observed for all forms of digestive tract cancer (SMR = 1.30, 95% CI = 0.60-2.47). There were two cases of brain cancer when 0.24 was expected (SMR = 8.44, 95% CI = 1.02-30.49). No previous report has mentioned an association of brain cancer with chromate pigments; however, because of the small numbers involved, a chance excess should be considered.

Adult↗
PubMed1995

Designations F18ab and F18ac for the related fimbrial types F107, 2134P and 8813 of Escherichia coli isolated from porcine postweaning diarrhoea and from oedema disease.

The relatedness of the fimbriae produced by eight E. coli strains including type strains with F107 fimbriae, 2134P pili and colonization factor 8813 (preliminary F18), was examined. These strains had been isolated principally from pigs which were affected with postweaning diarrhoea or with oedema disease. The fimbriae were analyzed by means of electron microscopy, slide agglutination, immunofluorescence, immunogold labelling, immuno-diffusion, immunoelectrophoresis and western blot, molecular genetic techniques, and in vitro adhesion. The fimbriae of all the strains were long flexible filaments with a diameter not larger than 4.6 nm showing a zig-zag pattern. Results obtained by the serological techniques confirmed that the fimbriae possessed a common antigenic determinant designated 'a' in addition to a variant-specific determinant designated 'b' or 'c'. Immunoelectron microscopy demonstrated that the determinants 'a' and 'b' or 'a' and 'c' were localized along the same fimbrium. In immunoelectrophoresis, fimbrial extracts of selected strains yielded a single precipitation line towards the cathode. One single major subunit of approximately 15 kDa was recognised in western blots by antisera against the common antigenic determinant and the variant specific determinants. All strains possessed sequences related to gene fedA, coding for the major subunit of fimbriae F107. Two types of fedA-related subunit genes were differentiated, corresponding to the 'ab' and 'ac' types of fimbriae as defined by serological methods. The results demonstrated that F107 fimbriae, 2134P pili and colonization factor 8813 are related, and that two serological variants can be distinguished. We propose designations F18ab (for F107), and F18ac (for 2134P and 8813) in analogy to the nomenclature of F4 fimbriae.

Animals↗
PubMed1995

Mortality from cardiovascular diseases among potash miners exposed to heat.

We assessed mortality rates in a cohort of French potash miners between 1977 and 1987. The cohort comprised all workers of a potash mine active on January 1, 1977, or subsequently hired, with at least 3 years of employment. We compared the mortality of the subcohort exposed to heat from underground work (U) with the mortality of those who had never worked underground (D). The overall mortality was low [standardized mortality ratio (SMR) = 0.89, based on 570 deaths] and was lower among underground workers (age-standardized mortality rate = 660 per 100,000 person-years, 266 deaths) than among daylight workers (age-standardized mortality rate = 710 per 100,000 person-years, 304 deaths). Mortality from ischemic heart diseases (IHD) was higher for underground workers than for daylight workers (relative risk = 1.6). As exposure to heat decreased over time, we analyzed the mortality according to period of hire: within underground workers, we observed a downward trend for mortality from IHD which contrasted with a stable mortality from IHD among daylight workers. Among subjects who left for medical reasons, IHD mortality was five times greater in the heat-exposed group compared with daylight workers. The data are consistent with an increased risk of ischemic heart diseases from a hot environment that is offset by a strong healthy worker effect.

Cardiovascular Diseases↗
PubMed1995

Survey of the respiratory health of the workers of a talc producing factory.

OBJECTIVES: To assess the effect of an occupational exposure to talc dust on respiratory health. METHODS: 166 talc millers from a French factory underwent spirometry and filled in a standardised respiratory questionnaire during their annual medical visit in 1989. A full sized chest radiograph taken in 1987 for the subjects hired before 1982 was also available, for the others a radiograph taken when hired was used. Radiography was repeated in 1992 for all subjects still active at this date (n = 139). The occupational exposure to talc dust was characterised for each workplace with 1440 personal samples collected since 1986 and by semiquantitative estimates of the historical exposure. RESULTS: The geometric mean (range) of estimated exposure was 1.87 (0.5 to 50) mg/m3 and the estimated cumulative exposure at the date of spirometry was > 150 y mg/m3 for 41 subjects. After adjustment for smoking in a linear model the standardised residual values of both forced vital capacity and forced expiratory volume in one second decreased significantly with increasing exposure. The prevalence of dyspnoea also increased after adjustment for smoking categories and age in a logistic regression. The prevalence of small radiological opacities was significantly related to age and to the exposure after adjustment for age and smoking categories. The incidence of new opacities between the two radiographs (11 new opacities with a profusion higher than 0/1) was significantly related to smoking (10 out of 11 are smokers) but not to the exposure. CONCLUSION: This study shows an effect of high levels of talc dust both on functional variables and on the prevalence of small radiological images, but provides no clear evidence about the possible effect of present levels of exposure.

Adult↗
PubMed1995

[Mortality due to bronchopulmonary cancers in workers of 2 foundries].

A mortality study was carried out in two factories producing stainless steel in order to assess lung cancer risk among workers employed in coke oven, blast and open hearth furnaces, foundry, electric furnace, hot and cold rolling mills and pickling areas. Occupational exposures of interest were chromium compounds, nickel compounds, polycyclic aromatic hydrocarbons (PAH), silica and asbestos. All male workers having at least one year of employment between 01.01.1960 and 31.12.1990 were followed up for mortality. The vital status was assessed from birth place registries. Complete job histories since date of first employment were abstracted from the company files. The smoking habits of 50% of the cohort members were known from medical records. The observed number of deaths (obs) were compared with the expected ones based on regional rates with adjustment for age, sex and calendar time (Standardized Mortality Ratio, SMR). The cohorts included 6324 (factory 1) and 5270 (factory 2) workers. The overall mortality did not differ markedly from that expected in both factories: SMR = 0.95 (obs = 1540, p = 0.05) in factory 1 and SMR = 1.06 (obs = 916, non-significant) in factory 2. SMRs for lung cancer did not differ from unity, respectively 0.99 (obs = 105) and 1.00 (obs = 54), in whole cohorts. Non-significant lung cancer excesses were observed among workers of some workshops where exposures of interest might have occurred: coke oven (SMR = 2.04), blast furnace (SMR = 1.36), open hearth furnace (SMR = 1.75), hot rolling mills (SMR = 1.29). These processes, however, are no longer involved in the study factories. Furthermore, no lung cancer excess was observed among workers employed in current workshops: electric furnaces and cold rolling mills.

Adult↗
PubMed1994

A retrospective mortality study of workers exposed to arsenic in a gold mine and refinery in France.

A historical mortality study of a cohort of employees of a gold mining and refining company was carried out in Salsigne, France. A major goal of the study was to investigate the relationship between lung cancer mortality and exposure to arsenic, radon, silica, and other contaminants of the working environment. A twofold excess of lung cancer was found both among miners and smelters, mainly concentrated among workers who had experienced exposure to past levels of arsenic, radon, and silica. The consistency of the results in the mine and the refinery are suggestive of a carcinogenic risk from both soluble and insoluble arsenic, although the potential role of other factors cannot be dismissed.

Arsenic Poisoning↗