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Biomedical subjects

P Wild

Publications and source records attributed to P Wild.

At least 91 records · Page 5Linked to original sources
PubMed1990

Adhesive fimbriae produced in vivo by Escherichia coli O139:K12(B):H1 associated with enterotoxaemia in pigs.

Two strains of E. coli O139:K12 (B):H1 were compared in vitro and in the intestinal environment. Both strains colonized the small intestines of experimentally inoculated pigs and exhibited in vivo a similar relationship to the microvillus border as enterotoxigenic E. coli (ETEC). Strain 107/86 grown on blood agar expressed numerous long flexible non-haemagglutinating fimbriae which were antigenically distinct from the known fimbriae of porcine ETEC. It adhered in vitro to porcine enterocyte brush border fragments. Strain 124/76 grown on blood agar was devoid of fimbriae and did not adhere to brush border fragments. However, fimbriae morphologically and antigenically indistinguishable from those of strain 107/86 were detected in the intestinal environment by direct immunofluorescence and by immuno electron microscopy.

Animals↗
PubMed1990

Mortality study among workers producing ferroalloys and stainless steel in France.

A mortality study was carried out among the workers of a plant that had produced ferrochromium and stainless steel, and was still producing stainless steel, in order to determine whether exposure to chromium compounds, to nickel compounds, and to polycyclic aromatic hydrocarbons (PAH) could result in a risk of lung cancer for the exposed workers. The cohort comprised 2269 men whose vital status were recorded between 1 January 1952 and 31 December 1982. The smoking habits of 67% of the cohort members were known from medical records. The observed numbers of deaths were compared with the expected ones based on national rates with adjustment for age, sex, and calendar time. A low mortality, achieving statistical significance, was found from all causes (observed = 137, standardised mortality ratio (SMR) = 0.82) and from benign respiratory diseases (observed = one, SMR = 0.15). With regard to mortality from lung cancer, a non-significant excess appeared in the whole cohort (observed = 12, SMR = 1.40). Among the exposed workers, however, a significant lung cancer excess was found (observed = 11, SMR = 2.04) that contrasted with a low SMR (0.32) in the non-exposed group. This excess is unlikely to be explained by smoking, as the tobacco consumption of these two groups was similar. No trend was observed for mortality from lung cancer either according to time since first exposure, or according to duration of exposure. A nested case-control study clearly suggested that this excess of deaths from lung cancer was attributable to former PAH exposures in the ferrochromium production workshops rather than to exposures in the stainless steel manufacturing areas.

Case-Control Studies↗
PubMed1989

Effects of estradiol on parathyroid cell activity.

Beta-estradiol-3-benzoate provoked an initial centrifugal membrane shift in rat parathyroid cells and, later, enlargement of the compartments concerned with parathyroid hormone secretion, which suggests that estradiol modulates not only transport and release of parathyroid hormone but also the capacity for its synthesis, packaging and storage.

Animals↗
PubMed1989

Arc welders' respiratory health evolution over five years.

The respiratory health of 138 arc welders and 106 control subjects in the same company was studied in 1981 and in 1986. Most of the subjects welded mild steel using the Metal Inert Gas (MIG) process. The controls were workers in the same company, not exposed to any known pulmonary risk. The welders and controls in the analysis had not changed their professional activity nor their smoking habits during these five years. The examinations consisted of a questionnaire on respiratory symptoms, a thoracic auscultation, a chest X-ray and lung function tests: flow-volume curve and steady state CO transfer test. The examinations in 1986 confirmed the risk of non specific radiological impairment (pulmonary reticulo-micronodulation) and of obstruction in the small bronchi, which had already been observed in 1981 in the arc welders in this company. These impairments did not seem to have evolved more than in the controls, but do however justify regular surveillance of the respiratory health of arc welders.

Adult↗
PubMed1989

Potency of microwave irradiation during fixation for electron microscopy.

Liver, skeletal muscle, peripheral nerves, pancreas, thyroid and adrenal cortex were prepared for electron microscopy employing microwave energy either during prefixation with glutaraldehyde or instead of prefixation. Microwave irradiation in the presence of glutaraldehyde in Na/K-phosphate or Na-cacodylate containing CaCl2 and MgCl2 led to distinct appearance of membranes, mainly plasma membrane, and membranes of SER, Golgi complex and mitochondria in liver, pancreas and muscle. The area of high quality fixation, however, was limited to the periphery of samples. On the other hand, SER was dilated in cells of the adrenal cortex, and RER markedly vacuolated in thyroid follicular cells. Microwave irradiation in the presence of Na/K-phosphate and subsequent osmication resulted in preservation of the ultrastructure in similar quality as was obtained by osmication without previous immersion in glutaraldehyde. However, the preservation of SER and Golgi complex in liver and pancreas, and of mitochondria in muscle was greatly improved. Small myelin sheaths remained intact whereas large ones showed focal disintegration. We consider that enhancement of fixation by microwave energy may greatly improve preservation of membranes in some tissues. Successful fixation depends on the use of glutaraldehyde during microwave irradiation, the type of buffer, the addition of ions to increase stabilization, the exposure time to heat, and on postosmication.

Adrenal Cortex↗
PubMed1989

Quantitative assessment of cellular changes provoked by microwave enhanced fixation of parathyroids.

Rat parathyroids fixed by microwave enhancement, i.e. microwave irradiation in the presence of glutaraldehyde for 8 s and postfixation with OsO4 after a delay of 5 min, were compared with parathyroids fixed by perfusion with glutaraldehyde followed by immersion in glutaraldehyde and finally in OsO4. Morphometric analysis revealed that microwave enhanced fixation led to a larger mean cell volume, to larger cell surface area, and to larger surface area in membranes of RER and secretory granules. Though it is not known by which method parathyroid cells are conserved closer to the living state it is obvious that microwave enhanced fixation retains more membranes but provokes centrifugal dislocation of membranes mimicking exocytosis.

Animals↗
PubMed1989

Risk of lung, larynx, pharynx and buccal cavity cancers among carbon electrode manufacturing workers.

Among workers employed in factories producing carbon graphite products the risk of cancer due to exposure to polycyclic aromatic hydrocarbons was estimated. In one cohort (plant A), a cancer incidence study was carried out; the number of cases were not significantly increased for lung cancers [7 cases, standardized incidence ratio (SIR) 79] or for cancers of the upper respiratory and alimentary tract (10 cases, SIR 103). In another cohort (plant B), a mortality study was carried out; neither the mortality from lung cancer [13 deaths, standardized mortality ratio (SMR) 118] nor that from upper respiratory and alimentary tract cancers (10 deaths, SMR 125) was significantly higher than expected. Within each cohort, a case-referent study was carried out. In plant A the odds ratios were high but nonsignificant for lung cancers (odds ratio 3.42) and upper respiratory and alimentary tract cancers (odds ratio 2.19) and they showed a nonsignificant relationship with duration of exposure. In plant B, the odds ratios were low for every cancer site.

Carbon↗
PubMed1988

Respiratory health assessment by questionnaire of 2024 workers involved in man-made mineral fiber production.

A respiratory health questionnaire was administered to the workers producing man-made mineral fibers in three glasswool and two rockwool plants in France, in order to detect adverse effects resulting from fiber exposure. The mean ages of the 2024 male participants ranged from 32 to 41 years. The standardized questionnaire was filled in by the industrial physicians: occupational history, smoking habits, respiratory symptoms (cough, phlegm, dyspnea, asthma), irritative complaints of the upper airways (nasal fossae and sinuses, pharynx and larynx) were all recorded. Multiple unconditional logistic regression was used to test for a relationship between possible explanatory variables and these symptoms. The prevalence of respiratory symptoms (cough, phlegm, dyspnea) was strongly correlated with age and increased markedly among current smokers. Having adjusted for these confounding factors, significantly elevated Odds Ratios (ORs) for cough and phlegm were observed among the workers of one plant (51% of the whole study population) who had been exposed to fibers for a long time. In the same plant, the ORs for complaints of nasal fossae and sinuses increased significantly with the duration of fiber exposure, and one elevated OR was observed for pharyngeal and laryngeal symptoms. These findings were not consistent with the results observed in the four other plants (49% of the study population), since ORs for all these symptoms were either low or not significantly increased according to the duration of fiber exposure. This lack of similarity among plants could be explained either by differences in interviewers, age, seniority and tobacco consumption, or by secular changes in the industrial processes involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Decreased serum ceruloplasmin concentration in aluminum welders exposed to ozone.

During an epidemiological survey on arc welders, serum copper and ceruloplasmin were determined in two groups of workers. One group consisted of aluminum welders who were divided into two groups: 13 welders working inside aluminum tanks (confined atmosphere) and 8 welders engaged in the production of vans for dump trucks (nonconfined atmosphere). The reference group consisted of 26 workers of the same plant who were not exposed to welding fumes. Ozone, the major pollutant in aluminum arc welding, was thought to be the principal factor in the significant decrease (P less than 0.01) of mean ceruloplasmin in confined welders. This decrease in the level of ceruloplasmin was still within the reference values and was not linked to age or to tobacco consumption. We found a linear relationship between ceruloplasmin concentration and the cumulated worktime along the week. This effect could be a sign in the serum of a lung reaction against oxidant activity in this type occupational exposure.

Adult↗
PubMed1988

Unimpaired membrane dynamics in parathyroid cells in insulin deficient rats.

The responsiveness of parathyroid cells in insulin deficient and short-term diabetic rats was investigated by morphometric analysis. Insulin deficiency was produced by intravenous injection of D-mannoheptulose and short-term (7 days) diabetes mellitus by intraperitoneal application of streptozotocin. Parathyroid glands were stimulated for parathyroid hormone secretion by decreasing the serum calcium concentration through intravenous infusion of EGTA. Parathyroid cells of controls, insulin deficient, and short-term diabetic rats responded to reduced serum calcium by a 45% increase of the cell surface area. This increase is assumed to be the result of the membrane-bound transport of parathyroid hormone from the Golgi complex and secretory granules to the plasma membrane and subsequent exocytic release of parathyroid hormone induced by the low serum calcium concentration. Therefore, the unimpaired increase in the cell surface area of parathyroid cells in insulin deficient and short-term diabetic rats indicates that insulin does not modulate the release of parathyroid hormone. It is also considered likely that synthesis of parathyroid hormone is not suppressed in short-term diabetes but that fat metabolism is disturbed leading to accumulation of lipid vacuoles.

Animals↗
PubMed1988

[Epidemiologic study of the mortality among the employees of a coal tar distillery].

A mortality study was carried out, throughout the period 1970-1984, in a cohort of 963 men who had worked for at least one year in a coal tar distillery. The observed number of deaths, 109, did not significantly differ from the expected number. Using the death rates of the local population as a reference, no excess was observed for lung cancer and for cancers of the larynx, while there was an excess for cancers of the oesophagus but non significant and for cancers of the buccal cavity and pharynx (SMR = 2.17 - p less than 0.05). A nested case-control study was carried out. From within the cohort, 5 deaths from lung cancer and 10 deaths from cancers of the buccal cavity and pharynx were defined as "cases". For each case, all the available dead controls with the same sex, year of birth, tobacco and alcohol consumption were selected from within the cohort. The odds ratios for lung cancer did not reveal any occupational risk. With regard to buccal cavity and pharyngeal cancers, the odds ratios were neither significant for a duration of exposure greater than or equal to 1 year nor for a duration greater than or equal to 5 years along with a latent period greater than or equal to 10 years. Nevertheless there is a significant OR for exposure less than or equal to 10 years (OR = 7.56) but it is near one for exposures greater than 10 years.

Adolescent↗
PubMed1987

Murine glia cells in culture can be stimulated to generate reactive oxygen.

Induction of luminol-enhanced chemiluminescence (CL) indicative of reactive oxygen formation was studied in glia cell cultures from newborn mice. A burst of CL could be induced by phorbol myristate acetate, zymosan, and antibody-coated bovine red blood cells, whereas Sendai virus and several other agents known to induce CL in myeloid cells were ineffective. Sodium azide failed to inhibit CL, indicating a myeloperoxidase-independent mechanism of light emission. In parallel experiments we identified the cells binding antibody-coated erythrocytes as macrophages characterized by the reduction of nitroblue tetrazolium and phagocytosis of zymosan and latex particles. Brain macrophages may use reactive oxygen intermediates (ROI) as a mechanism of antimicrobial defence; and, on the other hand, ROI formed by these cells may contribute to immuno-pathology in the brain.

Acridines↗
PubMed1987

Parathyroid cell variants may be provoked during immersion fixation.

Parathyroid glands of cattle, dogs, cats, mice and rats were immersed in glutaraldehyde or mixtures consisting of glutaraldehyde, formaldehyde and acrolein in either Na-phosphate, Na/K-phosphate or Na-cacodylate buffer, and postfixed with OsO4 in the same buffers or, alternatively, in s-collidine. Excellent preservation of bovine, feline and murine parathyroid glands was achieved with fixation mixtures containing 1% glutaraldehyde, 1.5-2% formaldehyde and 2.5-5% acrolein in 0.1 M Na-cacodylate with or without Ca2+ and Mg2+, Na-phosphate or Na/K-phosphate at 4 degrees C followed by postfixation with 1% OsO4 in the same buffers or in s-collidine containing sucrose, Ca2+ and Mg2+. This procedure largely abolished the occurrence of parathyroid cell variants. Bovine parathyroid glands were also satisfactorily preserved with 1% glutaraldehyde and 2% formaldehyde whereas 1% glutaraldehyde and 2.5 or 5% acrolein, lower or higher buffer osmolarity, or immersion at room temperature led to vacuolization of RER and to breakdown of membranes. In contrast, all fixation protocols led to the formation of dark and light cell variants and to multinucleated syncytial cells in dog and rat parathyroids. The results thus show that parathyroid cell variants arise during immersion fixation and that aldehydes, buffers and temperature are important factors for provoking parathyroid cell variants.

Aldehydes↗
PubMed1987

Isotope computed tomography using cone-beam geometry: a comparison of two reconstruction algorithms.

A CT scanner has been constructed specifically to determine the three-dimensional distribution of bone mineral in the medullary cavities of the radius, ulna and femur. A source of x-rays (153Gd) and a multiwire proportional counter (MWPC) are mounted at opposite ends of a diameter of an annular mounting. The limb is placed on the axis of rotation of the annulus and a series of two-dimensional transmission projections are obtained at equal angular spacings over 360 degrees. The distribution of bone mineral is reconstructed from the projections either by the method of maximum entropy (ME) or by convolution and back projection (CBP). These two methods have been evaluated by reconstructing a single slice of a phantom, representing the forearm, from projections simulated by computer. With a clinically acceptable exposure time, the mean medullary densities of the ulna and radius were determined with systematic errors of less than 3.5% (ME) and 11% (CBP), although for the latter method of reconstruction the systematic error was reduced to less than 2% by increasing the number of views. The mean medullary densities of the ulna and radius were determined with precisions better than 2.5% (ME) and 3.5% (CBP).

Algorithms↗
PubMed1987

["Physiologic" aging in 5 years of pulmonary function in 140 iron miners].

Ageing of the lung function in 5 years was studied in a group of 140 iron-ore miners, aged initially from 36 to 55 years. These men had no respiratory symptom and no pulmonary radiological abnormality. The sample was stratified on age and smoking. These factors were studied by a two-way analysis of variance. Lung function testing was performed twice, at 5 years of interval, in the same conditions. It consisted in: spirometry (for measuring FVC, FEV1, FEV1/FVC); a bronchial challenge test with acetylcholine (measurement of the fall of FEV1 after the test); measurement of total lung capacity (TLC) and residual volume (RV) by the open-circuit helium dilution method, and measurement of the transfer factor of the lung for CO, by the steady-state method (TCO/V). The only indices, whose values significantly changed in 5 years were: FVC, FEV1 and TCO/V. Their decrease rate did not appear to be significantly linked to age nor to smoking. According to these results, it seems that the decline of the pulmonary function is relatively constant during the middle period of life and that it is not strongly influenced by smoking, but only among subjects who remain without any respiratory symptom.

Adult↗
PubMed1987

Parathyroid ultrastructure after aldehyde fixation, high-pressure freezing, or microwave irradiation.

Parathyroid cell variants, commonly observed in parathyroid glands fixed by immersion in glutaraldehyde, are believed to be the result of cyclic changes in the course of parathyroid hormone secretion. Immersion of bovine parathyroid glands in a mixture consisting of 1% glutaraldehyde, 1.5% formaldehyde, and 2.5% acrolein, followed by post-fixation in 1% osmium tetroxide, resulted in high uniformity with only one cell variant, whereas the same fixation procedure led to disruption of cell membranes and formation of cell variants in rat parathyroids. Parathyroid glands of both cattle and rats prepared by high-pressure quick-freezing and subsequent freeze-substitution contained only one cell variant. Excellent preservation of the ultrastructure of bovine and rat parathyroids, also exhibiting only one cell variant, was achieved by microwave irradiation in the presence of 2.5% glutaraldehyde in Na-cacodylate followed by post-fixation with OsO4 in Na-cacodylate or s-collidine, both containing Ca2+ and Mg2+. Use of the appropriate buffer, as well as osmication, is essential for successful fixation utilizing microwave energy. The main effects are considered to be heating specimens within sufficient short periods and enhancement of subsequent osmium fixation. The results support the idea, arising after examination of perfusion-fixed parathyroid tissue, that parathyroid cell variants occur during improper aldehyde fixation rather than that they express functional diversity.

Air Pressure↗