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I Jahn

Publications and source records attributed to I Jahn.

28 records · Page 2Linked to original sources
PubMed1994

Human factor B. Complete cDNA sequence of the BF*S allele.

The gene of human complement factor B (BF) is located within the class III region of the major histocompatibility complex. The knowledge of the coding sequence of the BF gene rests on a set of partial sequence studies reported by various sources, and full-length sequences ascribed to specific alleles of this polymorphic complement component have not yet been published. Now, we have isolated and sequenced a collection of cDNA clones derived from BF*S, the major BF allele. We present an uninterrupted, allele-specific sequence of the entire coding region and the 3' untranslated segment of the cDNA. Extensive comparison of this and previously available sequence data was carried out, and a number of base substitutions were observed in relation to some of the earlier sequences. The possibility that these differences arise from polymorphism in the BF gene is discussed.

Alleles↗
PubMed1994

Genomic analysis of the F subtypes of human complement factor B.

Factor B of human complement is encoded within the Major Histocompatibility Complex (MHC) and is polymorphic, with up to 30 alleles defined by electrophoretic mobility. One of the most common alleles, BF*F, is subdivided into the FA and FB subtypes, which differ at the gene level by non-synonymous base substitutions in the seventh codon. We have found at this position a new restriction site polymorphism, as a Bsl I site absent from the FB allele. Using this restriction polymorphism, we have developed a method for BF F subtype determination, based on amplification by polymerase chain reaction of the 5' end of the BF gene, and digestion with Bsl I. This new method has been applied to a panel of 29 selected BF F individuals. A single strand DNA conformation analysis of the same region of the gene allowed us to confirm the above DNA-based BF F subtyping. During this study, two BF*F1 alleles showed discrepancies between protein and DNA typing, which were confirmed by our sequencing data. These were identical, in the 5' region, to BF*S and BF*FB genes, respectively. In a comparison with two protein subtyping methods, identical results were found for only one third of the selected samples. The conflicting results may arise, in part, from previously undescribed molecular heterogeneity within BF F subtypes, or from the presence of a null allele. Our new method allows BF*F subtyping to be used with confidence in the definition of disease-associated MHC haplotypes.

Alleles↗
PubMed1992

Occupational and environmental hazards associated with lung cancer.

In a hospital-based case-control study 194 lung cancer cases, 194 hospital controls, and 194 population controls were interviewed for their smoking, occupational, and residential history by trained interviewers, using a standardized questionnaire. In order to include many different environmental exposures, case ascertainment took place in seven different hospitals with catchment areas ranging from rural to highly industrialized. Lung cancer risk strongly increases with cumulative cigarette dose, reaching an odds ratio (OR) of 16.19 (95% confidence limits (CL): 5.10, 51.33) for male smokers of more than 40 pack-years and an OR of 19.99 (95% CL: 4.98, 80.24) for female smokers of more than 20 pack-years. For the quantification of occupational exposure to known carcinogens of the lung a novel approach was developed which accumulates exposure information obtained by supplemental questionnaires through an automatic procedure. The OR for the highest exposure group in males was 2.7 (95% CL: 1.23, 5.78). Significantly increased risks were observed in the metal industry, particularly in smelter and foundry workers (OR 4.8, 95% CL: 1.15, 20.16) and in turners (OR 2.2, 95% CL: 1.05, 4.75). In the construction industry the risks were particularly high in road construction workers (OR 3.7, 95% CL: 1.06, 13.20) and in unskilled construction workers (OR 2.7, 95% CL: 1.24, 5.76). The risks in these occupational groups increased with duration and with latency. Quantification of air pollution was done on a county basis by time period. An index based on emission data for sulphur dioxide was compared to a semiquantitative index, which included additional information on ambient air pollution. After adjustment for smoking and occupational exposures an OR of 1.01 (95% CL: 0.53, 1.91) for an emission index and of 1.16 (95% CL: 0.64, 2.13) for a semiquantitative index was obtained.

Adult↗
PubMed1990

C2 reference typing report.

Thirty samples contributed by seven laboratories to the VIth Complement Genetics Workshop were analyzed by isoelectric focusing and immunoblotting with a specific antihuman C2 antibody for the study of the polymorphism of native, activated and desialated C2. This study allowed to compare almost all the C2 variants so far described and also several 'new variants'. According to our results, the C2 system consists of nine structural variants at the protein level which include the common C2 C, the less common C2 B (in Caucasoids), four rare acidic and three rare basic variants. The polymorphic site for the basic variants is carried by the C2a fragment. Typing of desialated C2 is necessary to identify rare acidic or basic variants, especially the C2 BH and C2 BJ variants which seem difficult to be recognized in the native protein.

Antibodies↗
PubMed1990

[Results of the histology of bronchial carcinoma form an epidemiological study in North Rhine-Westphalia and northern Germany].

In a case-control study to examine the risk factors for bronchial carcinoma, 194 histologically confirmed cases of lung cancer and twice the number of controls (194 hospital controls, 194 population controls) were covered. In addition, the histological material obtained from 139 patients was assessed by a reference pathologist. In 107 cases (77%) the data coincided with the findings by the hospital pathologists. In women, young patients and persons with better general job qualifications adenocarcinomas and other bronchial carcinomas were seen more often and small-cell carcinomas as well as squamous cell carcinomas were rarer. Smoking did not entail any significant difference in respect of bronchial carcinoma risk. There was a significant risk increase among persons occupationally exposed to polycyclic aromatic hydrocarbons, arsenic, chromium, nickel and radionuclides in respect of squamous cell and small-cell carcinomas but not of adenocarcinomas and other histological types of carcinoma.

Adenocarcinoma↗
PubMed1990

[Results of the epidemiology of lung cancer in females].

In the context with an extensive pilot study investigating risk factors for lung cancer, aetiological and clinical questions were analysed for lung cancer mortality in women. In a first step all available data sources about the prevalence of smoking in the FRG were used to determine the correlation between the prevalence of smoking and lung cancer mortality. 88% of the variance (R2) of lung cancer mortality for women could be explained by smoking. In a second step medical records of 133 female lung cancer patients from three hospitals were analysed with regard to the histological types of lung cancer and smoking. Small cell lung cancers were more frequent among female smokers while adenocarcinoma was more prevalent among non-smokers. Survival analysis for 421 men and 97 women showed a significantly longer survival time for women as compared to men, taking into account other relevant prognostic factors. The association between smoking and lung cancer is discussed and analysed in greater detail.

Cause of Death↗
PubMed1987

[Not Available].

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Education, Medical↗