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Biomedical subjects

K Wegener

Publications and source records attributed to K Wegener.

At least 19 recordsLinked to original sources
PubMed2000

Ras gene mutations in vinyl chloride-induced liver tumours are carcinogen-specific but vary with cell type and species.

Previous studies have shown that a high proportion (5/6) of human liver angiosarcomas (ASL) associated with exposure to vinyl chloride (VC) contains a GC-->AT mutation at the Ki-ras codon 13. This mutation, however, has not been found in 5 ASL or 2 hepatocellular carcinomas (HCC) induced in rats by VC. These 2 HCC did contain a mutation at codon 61 of the Ha-ras gene. In order to extend this study and further explore the mechanisms of tumour induction, an additional 6 ASL and 6 HCC induced in rats by VC were analysed for ras gene point mutations, as well as 10 rat and 10 murine ASL induced by vinyl fluoride (VF), and 5 ASL, 6 Kupffer cell sarcomas, 4 HCC and 2 cholangiocellular carcinomas induced by Thorotrast in rats. Tumour DNA was analysed by PCR-SSCP and direct sequencing. None of the rodent ASL contained a mutation at codon 13 of the Ki-ras gene showing that the ras gene mutational pattern is species-specific. The CAA-->CTA mutation, previously found at codon 61 of the Ha-ras gene in rat HCC, was observed in 5 further VC-induced HCC but was not detected in the Thorotrast-induced HCC, suggesting carcinogen-specificity. This mutation was also absent in VC-induced ASL, which supports the cell-specificity of the ras mutational pattern in chemically induced tumours. No predominant mutation was detected in VF- and Thorotrast-induced tumours. Thus, a given mutation in a tumour may be carcinogen-specific but also depend on the species and the cell type.

Animals↗
PubMed2000

Analysis of radon-associated squamous cell carcinomas of the lung for a p53 gene hotspot mutation.

Squamous cell lung carcinomas (SCC) from former employees of the Wismut uranium mining company (Saxony, Germany) were obtained from the Stollberg Archive in order to screen for p53 tumour suppressor gene codon 249 arg-->met hotspot mutations, a putative molecular bio-dosimeter of alpha-particle (radon) exposure (Taylor et al (1994) Lancet 343: 86-87; McDonald et al (1995) Cancer Epidemiol Biomarkers Prevent 4: 791-793). Of the 29 archived samples of SCC meeting quality criteria for DNA analysis by polymerase chain reaction (PCR) and Haelll restriction enzyme digestion, two tumours were found that harboured this mutation. DNA sequencing confirmed the presence of a G to T base substitution within the Haelll site spanning codons 249 and 250 of the p53 gene that results in replacement of arginine (wild-type) by methionine at residue 249. When these data are combined with those from our previous study of tumours from the Stollberg Archive in which 50 lung tumours were examined, (including nine SCCs), we conclude that the G-->T (arg-->met) codon 249 mutation prevalence in the Wismut miner cohort is not sharply elevated in lung cancers in general (two mutations/79 tumours), or specifically in SCCs of the lung (two mutations/38 SCC) when compared to data from lung cancer patients with no reported occupational exposure to radon gas.

Carcinoma, Squamous Cell↗
PubMed1999

German uranium miner study--historical background and available histopathological material.

Mining activities in the former German Democratic Republic were documented as early as 1168 in the ore mountains (Erzgebirge) of Saxony. Silver, bismuth, cobalt, nickel and tungsten were mined from then up to the end of the 19th century. After the Second World War, the Soviet Occupation Authorities reopened the old silver mines in Saxony to mine uranium for the Soviet nuclear industry. About 400, 000 workers produced a total of 220,000 tons of uranium during the years 1946 to 1990. After the reunification of Germany, the archive of the Institute of Pathology of the mining area was opened for research. It contains protocols of 28,975 autopsy cases and about 400,000 slides collected from 1957 to 1992, about 66,000 tissue blocks, and 238 whole lungs. From the autopsy cases, 17,466 could be identified as workers of the uranium mining company. The remainder of the cases were in the population of the mining area. A comparison of the frequencies of malignancies of male workers older than 15 years with those of the population of the mining area for the years 1957 to 1989 demonstrates a significantly higher percentage of lung cancer among the uranium miners. There was no significant difference for other solid cancers and leukemias.

Cause of Death↗
PubMed1999

German uranium miner study--pathological and molecular genetic findings. German Uranium Miner Study, Research Group Pathology.

Uranium miners of the former Wismut company in Germany form the largest cohort of workers exposed to (222)Rn and dust in the world. The German Uranium Miner Study, Research Group Pathology, is evaluating the central pathology archive of the Wismut company. The main tasks of our study are pathological-anatomical and molecular genetic investigations of 28,975 autopsy cases and the evaluation of mining pollutants in the lungs by neutron activation analysis. As part of an observer agreement study, lung tumors are classified according to the WHO/IASLC classification and nontumorigenic lung disorders are registered. Lung tumors were analyzed for the presence of a proposed radon-specific mutation in the TP53 gene (formerly known as p53). Interim results are: (a) In the years 1957 to 1965, a high rate (69%) of small cell carcinomas was found which had declined to 34% by 1990. (b) The percentage of the deceased who suffered from silicosis is not higher in the group of lung tumors than in other tumor groups or the nontumor group. (c) The hypothesis of a radon-characteristic hotspot mutation in the TP53 tumor suppressor gene is not supported by our investigations. (d) Neutron activation analysis demonstrates that uranium, arsenic, chromium, cobalt and antimony can be found in tissue samples from the miners even when they had stopped working more than 20 years before death.

Genes, p53↗
PubMed1999

The german thorotrast study: recent results and assessment of risks.

The German Thorotrast study comprises 2,326 patients and 1,890 controls. Forty-eight Thorotrast patients and 239 controls are still alive and are invited for a follow-up examination every 2 years. In the deceased patients, the following neoplastic diseases with excess rates were registered (Thorotrast/controls): liver cancer (454/3); cancer of the bile ducts, including gallbladder (42/7); myeloid leukemia (40/7); myelodysplastic syndrome (30/4); plasmacytoma (10/2); non-Hodgkin's lymphoma (15/5); bone sarcoma (4/1); malignant peritoneal or pleural mesothelioma (9/0). Dose calculations are based on results of whole-body counting, X-ray films, and data obtained from the hospital records on the volume of Thorotrast injected. For liver cancer, the cumulative risk estimate was calculated to be 40 per 10(4) person Sv (radiation weighting factor = 20). These figures are close to the results of the Danish study and are comparable to the results of the Life Span Study of A-bomb survivors after 40 years at risk with 18 to 48 liver cancers per 10(4) person Sv. For hematopoietic malignancies, the cumulative risk was calculated to be about 7 per 10(4) person Sv (radiation weighting factor = 20). This risk estimate is lower by a factor of 10 compared to the results of the Life Span Study.

Adult↗
PubMed1997

p53 gene mutation analysis in tumors of patients exposed to alpha-particles.

The p53 gene was examined for point mutations in archived, alpha-radiation-associated lung and liver cancers. Lung tumors of 50 uranium miners in Germany were screened by restriction fragment length analysis for the putative hotspot mutation at codon 249 (Arg-->Met) previously detected in a significant fraction of miners from the Colorado Plateau, USA. This mutation has been proposed as a marker of radon exposure. None of the tumors we examined harbored the hotspot mutation. Five of the 50 tumors, however, did indeed harbor exon 7 mutations, as determined by subsequent mutation analysis of exon 7. These mutations were dispersed among various codons and may be attributable to heavy tobacco smoking in this cohort. In support of this interpretation, we found no mutations in exons 5-8 of the p53 gene in 13 iatrogenic liver cancers induced by injection of Thorotrast, an alpha-emitting radiocontrast agent. We propose that if the p53 tumor suppressor gene is a target for the carcinogenic action of alpha-particle radiation, loss of suppressor function may occur preferentially by mechanisms such as intrachromosomal deletions, rather than by base substitution mutations.

Aged↗
PubMed1995

[An oneiroid experience during severe acute polyradiculoneuritis].

This study is to present a psychopathological analysis of complex hallucinatory symptoms--without consciousness breaking up in confusional state--occurring in patients with acute Guillain-Barré's syndrome diagnosis requiring neurological intensive care. Finally the patients experience an unitary and closed situation "close to dream without being dream". This experience is corresponding to the semeiology of the "oneiroid experience" (Mayer-Gross, 1924). The "oneiroid experience" appears to be of syndromic nature independent of any etiological and/or nosological classification. But its conceptualization does probably need widening: the oneiroid world appears to be a creation of a primitive function which inserts us in the world before any science or verification.

Acute Disease↗
PubMed1994

Preneoplastic foci of altered hepatocytes induced in rats by irradiation with alpha-particles of Thorotrast and neutrons.

Prestages of hepatocellular neoplasms induced in rats by continuous internal alpha-radiation of Thorotrast or by fractionated external radiation with neutrons were studied by cytomorphological, cytochemical and morphometric methods. Irradiation with both Thorotrast and neutrons resulted in a significant increase in the number and volume fraction of foci of altered hepatocytes (FAH), the occurrence of which at 14 months correlated well with the previously reported increased incidence of hepatocellular neoplasms appearing after long lag periods. The morphological and biochemical phenotypes of radiation-induced FAH were similar to those of preneoplastic lesions described earlier in hepatocarcinogenesis elicited by chemicals or viruses.

Alpha Particles↗
PubMed1994

Sympathetic noradrenergic fibers as the source of immunoreactive alpha-neoendorphin and dynorphin in the guinea pig heart.

Dynorphin and alpha-neoendorphin bind to the kappa subtype of opioid receptors and have been shown to inhibit the release of noradrenaline from cardiac sympathetic axons. The purpose of this study was to elucidate the endogenous localization of dynorphin and alpha-neoendorphin in the guinea pig heart. This goal was achieved by double- and triple-labelling immunofluorescence. Dynorphin- and alpha-neoendorphin-immunoreactive nerve fibers were numerous around coronary blood vessels and among cardiomyocytes. They also contained immunoreactivities to the rate-limiting enzyme of catecholamine synthesis tyrosine hydroxylase and to neuropeptide Y. These fibers disappeared in response to chemical sympathectomy (6-hydroxydopamine treatment). In contrast, substance P/calcitonin gene-related peptide-immunoreactive axons of sensory origin did not contain dynorphin and alpha-neoendorphin immunoreactivities and were unaffected by chemical sympathectomy. The findings demonstrate that immunoreactive dynorphin and alpha-neoendorphin are contained in postganglionic sympathetic nerve fibers innervating coronary blood vessels and cardiac muscle. Therefore, the inhibitory effect of these peptides upon noradrenaline release from the sympathetic terminal may well be an autoinhibitory feedback loop.

Animals↗
PubMed1994

[Barrett esophagus with severe epithelial dysplasia--always surgery? A case report].

A 57 year-old patient presented with a Barrett's epithelium over the length of 18 cm. We found the typical functional changes of acid reflux and hypomotility in the distal esophagus. There was a history of chemotherapy for seminoma 30 years ago. Because of the repeated finding of severe dysplasia surgery was proposed. The patient died in the postoperative period with the signs and symptoms of pulmonary embolism. There was no invasive tumor found in the resected part of the esophagus. Main aspects of the etiology and histological characterism of Barrett's esophagus and the indication for surgery in cases with severe dysplasia are discussed.

Barrett Esophagus↗
PubMed1994

Translocation of Thorotrast in the body.

To investigate whether there is a permanent translocation of Thorotrast in the body, the liver of male Lewis rats was removed 4 weeks after injection of Thorotrast (300 microliters) and replaced by a donor liver. In half of the animals the spleen was removed as well. Measuring the 232Th content in the donor liver at different times after implantation demonstrated a permanent transport of 232Th into the surrogate organ. After 231 days a 232Th depot of about 1.1 mg was found, representing about 3% of the total body burden. The additional removal of the spleen resulted in a significantly lower transport of 232Th into the implanted liver. Histological examinations of the donated livers revealed increasing local concentration of Thorotrast granules, leading to the development of conglomerates. A comparable translocation of Thorotrast was verified in two humans who required liver transplantation more than 40 years after Thorotrast injection.

Animals↗
PubMed1994

[Mucinous cystadenomas and cystadenocarcinomas of the pancreas--the pancreaticoscopy as a new device for endoscopic and histological diagnosis].

Recent advances in diagnostic imaging procedures offer the opportunity for detection of rare cystic neoplasms of the pancreas. Cystadenomas of the pancreas have been reported to represent 10% of cystic pancreatic lesions. Serous microcystic cystadenoma, megacystic mucinous and duct-ectatic mucinous cystadenoma were distinguished. While the serous cystadenoma is benign, in general the megacystic and the duct-ectatic mucinous cystadenoma have a significant malignant potential. With pancreatoscopy, a rather new endoscopic technique, five cases of mucinous megacystic cystadenoma were diagnosed preoperatively by macroscopic and microscopic means. In one case, development of malignant neoplasm was diagnosed, one patient did not undergo surgery because of her age. Three patients were operated (total pancreatectomy in one case, duodeno-hemipancreatectomy in two cases) and are without any further signs of recurrence and free of symptoms in a one year to four year clinical follow-up.

Adult↗
PubMed1993

Vagus nerve stimulation for intractable seizures: one year follow-up.

Even with the best health care available, many patients with epilepsy still suffer from poorly controlled seizures. Patients with intractable partial seizures are often inhibited from realizing their full potential and may experience a less than optimal quality of life. Vagus nerve stimulation (VNS) is being studied in a double-blind, controlled, randomized trial at 17 epilepsy centers throughout the U.S. and Europe as a potential therapy for patients with refractory seizures. During a 14-week controlled phase in three of the centers, the therapeutic group (N = 10) experienced a mean seizure frequency percent reduction (SFPR) of 33.1% as compared to baseline (p = 0.0084) while the subtherapeutic group (N = 12) experienced an SFPR of 0.6% as compared to baseline (p = 0.9183). After the controlled phase, all patients were switched into the therapeutic group in an open extension phase. Results after one year of therapeutic stimulation (N = 15) reveal a mean SFPR of 35.6% (p = 0.0088) with 6 of the 15 patients (40%) achieving at least a 50% seizure reduction. Adverse effects included hoarseness, coughing and nausea. There were no deaths or serious injuries related to the device. Based on these limited data, VNS appears to be a safe and efficacious new therapy for refractory partial seizures.

Double-Blind Method↗
PubMed1992

[Ménétrier's disease--a rare cause of a protein deficiency syndrome].

Hypoproteinaemia (total proteins 5.2 g/dl) and hypoalbuminaemia (2.7 g/dl) were demonstrated in a 44-year-old woman with leg oedema during the previous four months and 10-kg weight gain during the previous year. A protein-losing enteropathy was diagnosed, all other causes having been excluded. Gastroscopy revealed giant hypertrophic gastritis. A biopsy showed foveolar hyperplasia with some inflammatory infiltrates, typical of Ménétrier's disease. Endosonography excluded any additional infiltrative process of the bowel wall. Long-term treatment with ranitidine, 150 g twice daily, achieved normalization of total protein and albumin concentrations. But the macroscopic changes in the gastric wall were still recognizable on repeat gastroscopy. As there is a danger of malignant degeneration gastroscopy and, if indicated, endosonography should be repeated annually.

Adult↗