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Biomedical subjects

J C Wagner

Publications and source records attributed to J C Wagner.

At least 19 recordsLinked to original sources
PubMed2005

Effective biasing schemes for duct streaming problems.

The effective use of biasing for the Monte Carlo solution of a void streaming problem is essential to obtaining a reasonable result in a reasonable amount of time. Most general purpose Monte Carlo shielding codes allow for the user to select the particular biasing techniques best oriented to the particular problem of interest. The biasing strategy for void streaming problems many times differs from that of a deep penetration problem. The key in void streaming is to bias particles into the streaming path, whereas in deep penetration problems the biasing is aimed at forcing particles through the shield. Until recently, the biasing scheme in the SCALE SAS4 shielding module was considered inadequate for void streaming problems due to the assumed one-dimensional nature of the automated bias prescription. A modified approach to the automated biasing in SAS4 has allowed for significant gains to be realised in the use of the code for void streaming problems. This paper applies the modified SAS4 procedures to a spent fuel storage cask model with vent ports. The results of the SAS4 analysis are compared with those of the ADVANTG methodology, which is an accelerated version of MCNP. Various options available for the implementation of the SAS4 methodology are reviewed and recommendations offered.

Algorithms↗
PubMed2000

Mortality from all cancers of asbestos factory workers in east London 1933-80.

OBJECTIVE: To give the observed and expected deaths due to cancer at all separate sites in asbestos workers in east London, and to analyse these for overall effect and exposure-response trend. METHODS: The mortality experience of a cohort of over 5000 men and women followed up for over 30 years since first exposure to asbestos has been extracted. RESULTS: There was a large excess of deaths due to cancer (537 observed, 222 expected). Most of these were due to cancer of the lung (232 observed, 77 expected) and pleural (52) and peritoneal (48) mesothelioma. The exposure-response trend for all these three causes was highly significant. There was also an excess of cancer of the colon (27 observed, 15 expected) which was significantly related to exposure. There were significant excesses of cancer of the ovary, of the liver, and of the oesophagus but with no consistent relation to exposure. CONCLUSIONS: The excess risk of cancer after exposure to asbestos was mainly due to cancer of the lung and mesothelioma. An exposure related excess of cancer of the colon was also detected but the possibility that some of these deaths may have been peritoneal mesotheliomas could not be excluded. There was no consistent evidence of exposure related excesses at any other site.

Asbestos↗
PubMed1998

Natural language generation of surgical procedures.

The GALEN-IN-USE project has developed a compositional scheme for the conceptual representation of surgical operative procedure rubrics. The complex representations which result are translated back to surface language by a tool for multilingual natural language generation. This generator can be adapted to the specific characteristics of the scheme by introducing particular definitions of concepts and relationships. We discuss how the generator uses such definitions to bridge between the modelling 'style' of the GALEN scheme and natural language.

Humans↗
PubMed1997

Evaluation of hepatitis C virus envelope proteins expressed in E. coli and insect cells for use as tools for antibody screening.

BACKGROUND/METHODS: The two envelope proteins of hepatitis C virus, E1 and E2, were expressed in E. coli and, as secretory proteins, in Sf9 insect cells using recombinant baculoviruses. Co-infection of insect cells with E1 and E2-recombinant baculoviruses was performed, which has been shown to result in formation of E1-E2 dimers. All envelope proteins were purified by Ni2+-NTA chromatography and used for screening of serum samples in a HCV EIA assay. Serum samples of normal blood donors, chronically HCV-infected patients, a mixed titer panel and several seroconversion panels were screened and compared to test results with Cobas Core Anti-HCV EIA. RESULTS: Screening of the sera of chronically HCV-infected patients (100% positive in Cobas Core Anti-HCV EIA) revealed 10-40% anti-E1 positive sera using different Sf9-expressed, glycosylated proteins and 93% using E. coli-expressed, non-glycosylated E1 protein. When the same sera were tested with different E2 proteins expressed in Sf9 cells and in E. coli, about 70-73% showed anti-E2 reactivity. When the proteins from Sf9 cells co-infected with E1- and E2-recombinant baculoviruses were tested, 70-80% of the same sera showed anti-envelope reactivity. CONCLUSIONS: Testing of these patient antisera, and those from the well-characterized mixed titer panel BBI-PHV203, showed that recombinant E1 expressed in E. coli and co-expressed E1 and E2 proteins from Sf9 cells could be used as additional tools for anti-HCV antibody screening.

Animals↗
PubMed1996

Anabolic steroid use among adolescents in Nebraska schools.

The extent of anabolic steroid use among adolescent sports participants and nonparticipants in Nebraska schools was studied. The Nebraska Secondary School Survey administered in 1991 contained 19 new items designed to determine rates of use of anabolic steroids and to measure participation in school sports. Schools participating in the survey are part of the Toward a Drug Free Nebraska training project; when the 1991 survey was conducted, training did not address ergogenic drug use. The survey was administered on a voluntary and confidential basis to Nebraska students in grades 7 through 12. A total of 4722 students in 62 secondary schools were surveyed; 3183 (67.4%) identified themselves as participants in school-sponsored sports. Of all the respondents, 117 (2.5%) reported having used anabolic steroids in the preceding 30 days. Some 4.5% of all the male respondents were steroid users, versus 0.8% of all the females. Of the students who reported using anabolic steroids, 72.6% were sports participants. Steroid users, whether they participated in sports or not, were more likely to use alcohol, tobacco, and other drugs than were nonusers of steroids. Among sports participants and nonparticipants, anabolic steroid users were more likely than nonusers to report acting violently. Nebraska students (grades 7 through 12) who participated in school-sponsored sports were more likely than non-participants to use anabolic steroids. Steroid-using athletes were more likely to use alcohol, tobacco, and other drugs than athletes who did not use steroids.

Adolescent↗
PubMed1995

Intrapleural administration of vitreous high duty ceramic fibres and heated devitrified ceramic fibres does not give rise to pleural mesothelioma in rats.

In order to determine whether they are potentially carcinogenic to the pleural mesothelium, three samples of ceramic fibre have been administered to rats by the intrapleural route. These samples were a high-duty grade refractory ceramic fibre (manufactured by Thermal Ceramics Ltd) in the as-manufactured vitreous state and two devitrified samples produced by heating the same fibre for 2 weeks at 1200 degrees C and for two weeks at 1400 degrees C. The mean lifespans of the groups of rats treated with vitrified and devitrified ceramic fibres were not significantly different from that of the control rats. In these studies none of the treated or control rats developed pleural mesothelioma, making it unlikely that ceramic fibres of this type, whether vitreous or devitrified, are potentially carcinogenic to the pleural mesothelium.

Animals↗
PubMed1995

Analysis of medical texts based on a sound medical model.

Automatic understanding of natural language is a complex task due to the presence of ambiguities. In particular, semantic ambiguities which are often immediately and unconsciously solved by human beings, are raised when analyzing natural language sentences by computer. The latter has to know the implicit and contextual information in order to resolve these difficulties. Nowadays in medicine, a considerable effort is deployed to model semantic contents of the medical domain. Such a task is usually performed separately from linguistic considerations. The goal of this paper is to highlight the key issues of basing a medical language processing system on a sound semantic model. To illustrate the requirements and advantages of such a conceptual approach to the analysis process, the experiment conducted to adjust the RECIT analyzer to the GALEN model is shown.

Models, Theoretical↗
PubMed1995

Multilingual natural language generation as part of a medical terminology server.

Re-usable and sharable, and therefore language-independent concept models are of increasing importance in the medical domain. The GALEN project (Generalized Architecture for Languages Encyclopedias and Nomenclatures in Medicine) aims at developing language-independent concept representation systems as the foundations for the next generation of multilingual coding systems. For use within clinical applications, the content of the model has to be mapped to natural language. A so-called Multilingual Information Module (MM) establishes the link between the language-independent concept model and different natural languages. This text generation software must be versatile enough to cope at the same time with different languages and with different parts of a compositional model. It has to meet, on the one hand, the properties of the language as used in the medical domain and, on the other hand, the specific characteristics of the underlying model and its representation formalism. We propose a semantic-oriented approach to natural language generation that is based on linguistic annotations to a concept model. This approach is realized as an integral part of a Terminology Server, built around the concept model and offering different terminological services for clinical applications.

Language↗
PubMed1995

Representing clinical narratives using conceptual graphs.

The analysis of medical narratives and the generation of natural language expressions are strongly dependent on the existence of an adequate representation language. Such a language has to be expressive enough in order to handle the complexity of human reasoning in the domain. Sowa's Conceptual Graphs (CG) are an answer, and this paper presents a multilingual implementation, using French, English and German. Current developments demonstrate the feasibility of an approach to natural Language Understanding where semantic aspects are dominant, in contrast to syntax driven methods. The basic idea is to aggregate blocks of words according to semantic compatibility rules, following a method called Proximity Processing. The CG representation is gradually built, starting from single words in a semantic lexicon, to finally give a complete representation of the sentence under the form of a single CG. The process is dependent on specific rules of the medical domain, and for this reason is largely controlled by the declarative knowledge of the medical Linguistic Knowledge Base.

Artificial Intelligence↗
PubMed1994

Fiber levels and disease in workers from a factory predominantly using amosite.

The Cape Boards Plant at Uxbridge produced insulation board containing amosite asbestos between 1947 and 1973 with only small amounts of chrysotile. After 1973 only amosite was used. In this study we examined lung samples from 48 workers who had been employed at the plant and who had come to autopsy. The study investigated the fiber levels against the lung pathology including amount of interstitial fibrosis and numbers of ferruginous bodies. The degree of interstitial fibrosis and number of asbestos bodies were graded and the tissues were analyzed by transmission electron microscopy and energy dispersive X-ray analysis and the fibers counted and typed. The 48 cases included 5 mesotheliomas and 14 lung cancers. The mineral analysis results were dominated by the amosite fiber levels. The amounts of chrysotile were relatively small. There were higher levels in lung cancer cases than mesotheliomas and higher levels in mesothelioma cases than those who had died from nonasbestos related diseases. Analysis of the lung tissues showed a consistent pattern of high amosite levels, which confirms the impression that amosite was the predominant form of asbestos used and also indicates that the factory had been a very dusty one.

Asbestos, Amosite↗
PubMed1993

A study of Spanish sepiolite workers.

BACKGROUND: Sepiolite is an absorbent clay that is used as pet litter. It forms thin crystals, which are a transition between chain and layered silicates. Inhalation studies in animals have shown no evidence of pulmonary damage. This paper reports a cross sectional study of the total work force of the largest sepiolite production plant in the world. METHODS: Two hundred and eighteen workers (210 men and eight women) were studied. Height, age, and smoking history were recorded. Chest radiographs were read according to the International Labour Office (ILO) classification by two readers. Readings were used to construct a numerical score, which was then used in statistical analyses. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were divided by the square of the height. Casella size selective personal samplers were used in randomly selected operatives to collect dust eight years before the rest of the study was carried out. These samples were evaluated gravimetrically. Total dust samples were examined by optical and electron microscopes. Results were analysed by bivariate linear regression, chi 2 tests, and analysis of variance. RESULTS: When allowance was made for smoking habit workers exposed to dry dust showed a significantly greater decline in FEV1 with age than workers with little exposure to dry dust. A similar pattern applied to FVC. Radiographic score showed deterioration with age but no clear differences from other variables. High concentrations of dust were found in the bagging department and also in the classifier shed. CONCLUSIONS: The major finding was that lung function deteriorated more rapidly in those who had had more exposure to dust, but there was no evidence of any accompanying radiographic change.

Adult↗
PubMed1993

[Double trans-suture technique in colorectal surgical anastomosis. Apropos of 45 cases].

The double trans-suture technique in colorectal anastomoses is an entirely mechanical one which consist of the transformation of two linear sutures in a circular one. During, 2 years, between March 1990 and March 1992, this technique was performed on 45 patients, of whom about two-third had a carcinoma of rectosigmoid. No postoperative mortality occurred. One patient developed an anastomatic stenosis, and another one a clinical leakage. The double trans-suture technique has not only the advantages of the double stapling technique but also avoids the incidents of performing a proximal purse.

Aged↗
PubMed1992

Purification and characterization of proteinase yscJ, a new yeast peptidase.

A newly recognized peptidase, designated proteinase yscJ, was purified from the yeast Saccharomyces cerevisiae. The enzyme is of non-vacuolar origin and cleaves the Tyr-Lys bond of the synthetic peptide substrate Cbz-Tyr-Lys-Arg-NH-Ph (Cbz, benzyloxycarbonyl; NH-Ph, 4-nitroanilide) and the Glu-Lys bond of the substrate Boc-Glu-Lys-Lys-NH-Mec (Boc, butoxycarbonyl; Mec, 4-methylcoumarinyl) with high efficiency. Optimum pH for cleavage of Cbz-Tyr-Lys-Arg-NH-Ph is in the range 7.0-7.5. The purified enzyme has a molecular mass of approximately 58 kDa, as judged by gel filtration on a Superose 12 FPLC column. Mercury compounds and EDTA were found to be potent inhibitors of proteinase yscJ activity.

Amino Acid Sequence↗
PubMed1991

Metabolic regulation of the trehalose content of vegetative yeast.

We have investigated the mechanism by which heat shock conditions lead to a reversible accumulation of trehalose in growing yeast. When cells of S. cerevisiae M1 growing exponentially at 30 degrees C were shifted to 45 degrees C for 20 min, or to 39 degrees C for 40 min, the concentration of trehalose increased by about 25-fold; an effect reversed upon lowering the temperature to 30 degrees C. This was compared to the more than 50-fold rise in trehalose levels obtained upon transition from the exponential to the stationary growth phase. Whereas the latter was paralleled by a 12-fold increase in the activity of trehalose-6-phosphate synthase, no significant change in the activities of trehalose-synthesizing and -degrading enzymes was measured under heat shock conditions. Accordingly, cycloheximide did not prevent the heat-induced accumulation of trehalose. However, the concentrations of the substrates for trehalose-6-phosphate synthase, i.e. glucose-6-phosphate and UDP-glucose, were found to rise during heat shock by about 5-10-fold. Since the elevated levels of both sugars are still well below the Km-values determined for trehalose-6-phosphate synthase in vitro, they are likely to contribute to the increase in trehalose under heat shock conditions. A similar increase in the steady-state levels was obtained for other intermediates of the glycolytic pathway between glucose and triosephosphate, including ATP. This suggests that temperature-dependent changes in the kinetic parameters of glycolytic enzymes vary in steady-state levels of intermediates of sugar metabolism, including an increase of those that are required for trehalose synthesis. Trehalose, glucose-6-phosphate, UDP-glucose, and ATP, were all found to increase during the 40 min heat treatment at 39 degrees C. Since this also occurs in a mutant lacking the heat shock-induced protein HSP104 (delta hsp104), this protein cannot be involved in the accumulation of trehalose under these heat shock conditions. However, mutant delta hsp104, in contrast to the parental wild-type, was sensitive towards a 20 min incubation at 50 degrees C. Since this mutant also accumulated normal levels of trehalose, we conclude that HSP104 function, and not towards a 20 min incubation at 50 degrees C. Since this mutant also accumulated normal levels of trehalose, we conclude that HSP104 function, and not the accumulation of trehalose, protects S. cerevisiae from the damage caused by a 50 degrees C treatment.

Glucose-6-Phosphate↗
PubMed1991

Background incidence of mesothelioma: animal and human evidence.

Evidence is presented showing that mesotheliomas can have causes other than exposure to asbestos dust, in both experimental animals and humans. In experimental animals, for example, results from two major experimental laboratories suggest that at least 10% may be taken for background incidence, whereas a third laboratory suggests that the experimental group must have a rate exceeding 30% "Background" also includes mesotheliomas found in association with nonfibrous and fibrous nonasbestiform agents. Mesotheliomas in humans can be broadly classified in a manner similar to those of experimental animals: (1) spontaneously occurring, (2) those with a latent period less than 10 years, (3) childhood mesotheliomas, (4) familial cases, (5) cases before the 20th century, (6) mineralogically negative mesotheliomas, and (7) mesotheliomas caused by nonasbestiform agents. The importance of the acceptance of these "background" cases lies in the fact that a basis is provided for the study of the incidence of disease associated with various types of asbestos.

Animals↗
PubMed1991

Carcinogenicity of the insulation wools: reassessment of the IARC evaluation.

In assessing the health evidence concerning man-made mineral fibers, the chemical composition, surface activity, durability, and size of fibers have to be taken into account. Special-purpose fine glass fibers need to be separated from the insulation wools (glass, rock, and slag wool). The epidemiological evidence is sufficient to conclude that there has been no mesothelioma risk to workers producing or using glass wool, rock wool, or slag wool. The epidemiological studies have been large and powerful, and they show no evidence of a cause-effect relationship between lung cancer and exposure to glass wool, rock wool, or slag wool fibers. There is some evidence of a small cancer hazard attached to the manufacturing process in slag wool plants 20 to 50 years ago, when asbestos was used in some products and other carcinogenic substances were present. However, this hazard is not associated with any index of exposure to slag wool itself. Animal inhalation studies of ordinary insulation wools also show that there is no evidence of hazard associated with exposure to these relatively coarse, soluble fibers. The evidence of carcinogenicity is limited to experiments with special-purpose fine durable glass fibers or experimental fibers, and only when these fibers are injected directly into the pleural or peritoneal cavity. Multiple chronic inhalation studies of these same special-purpose fine glass fibers have not produced evidence of carcinogenicity. It is suggested that the present IARC evaluation of the carcinogenic risk of insulation wools should be revised to Category 3: not classifiable as to carcinogenicity to humans.

Animals↗