Genetic differentiation among European whitefish ecotypes based on microsatellite data.

The amount of genetic differentiation at DNA microsatellite loci in European whitefish (Coregonus lavaretus) was assessed among ecotypes, populations and run-timing types. The magnitude of genetic changes potentially caused by hatchery broodstock rearing were also compared with those observed in corresponding natural populations. A total of 35 populations were studied, including 33 Coregonus lavaretus populations and two samples of Coregonus peled. Five of the six whitefish ecotypes in Finland were represented within C. lavaretus populations. Genetic diversity among C. lavaretus populations proved to be high compared to two C. peled populations. The genetic D(A) distance between these two species was as high as 0.86. The genetic differentiation among ecotypes was generally low and thus gives support for the hypothesis of one native European whitefish species in Scandinavia. Among the ecotypes the northern, large sparsely-rakered, bottom-dwelling whitefish was most unique. Thus, observed genetic differences in quantitative traits have either developed independently of phylogenetic lineages, or have mixed and later changed according to environments and selection pressures. Overall genetic distances between the anadromous whitefish populations along the Finnish coast, especially in the Bothnian Bay area, were small. Populations of this area have been heavily influenced by human activities, and they also have the highest probability of mixing by natural means. In two cases, the Rivers Iijoki and Tornionjoki, statistically significant genetic differences could be observed between summer- and autumn-run spawning-time types. Wild populations had slightly higher allelic diversity than hatchery-reared populations of corresponding rivers. Although some reduction in genetic diversity during hatchery rearing is possible, it is an important aid in maintaining endangered populations.

Analysis of the risk factors and their combinations in acute gastroduodenal ulcer bleeding: a case-control study.

OBJECTIVE: Traditional non-steroidal anti-inflammatory drugs (NSAIDs) including ASA for thrombosis prophylaxis (ASA-TP), for pain medication (ASA-P) or non-ASA NSAIDs (NANSAIDs), Helicobacter pylori infection, CagA strains of H. pylori and smoking are reported risk factors for peptic ulcer bleeding (PUB), but the combined and the dose effects of these factors are controversial. The aim of this study was to estimate the significance of these risk factors and their combinations in PUB. MATERIAL AND METHODS: PUB patients (n = 94) were compared with an age- (+/- 5 years) and gender-matched control group of non-ulcer patients (n = 94) attending elective endoscopy. A questionnaire on the possible risk factors (previous gastric and duodenal ulcer, use of ASA-TP, ASA-P, NANSAIDs, warfarin, alcohol and smoking) was completed. H. pylori infection was determined as positive if histology and/or urease tests were positive. CagA antibodies of IgG class were determined using an immunoblot method. RESULTS: H. pylori infection (odds ratio (OR) 8.8), the use of ASA-P (OR 3.5), ASA-TP (OR 4.07), NANSAIDs with > or =1 defined daily dose (OR 6.56), smoking > or =20 cigarettes daily (OR 6.43) and previous duodenal ulcer (DU) (OR 8.96) were independent risk factors for PUB. At least two risk factors were present in 65% of PUB patients. CagA strains were detected in 97% of the H. pylori-positive cases and in 96% of the respective controls. ASA, ibuprofen, ketoprofen and smoking were dose-dependent risk factors for PUB. CONCLUSIONS: Previous DU, H. pylori, the use of any ASA and smoking explained the majority of the PUB episodes. CagA strains of H. pylori were not associated with PUB. Two-thirds of the PUB patients had at least two risk factors, but their combination did not potentiate the risk.