Association of a variant in the muscarinic acetylcholine receptor 2 gene (CHRM2) with nicotine addiction.

Genetic factors contribute to the overall risk of developing nicotine addiction, which is the major cause of preventable deaths in western countries. However, knowledge regarding specific polymorphisms influencing smoking phenotypes remains scarce. In the present study we provide evidence that a common single nucleotide polymorphism (SNP) in the 5' untranslated region of CHRM2, the gene coding for the muscarinic acetylcholine receptor 2 is associated with nicotine addiction. CHRM2 was defined as a candidate gene for nicotine addiction based on previous evidence that linked variations in CHRM2 to alcohol and drug dependence. A total of more than 5,500 subjects representative of the German population were genotyped and assessed regarding their smoking habits. The impact of three SNPs in CHRM2 on smoking behavior/nicotine addiction was investigated using logistic regression models or a quasi-Poisson regression model, respectively. We found the T allele of SNP rs324650 to be associated with an increased risk of smoking/nicotine dependence according to three different models, the recessive models of regular or heavy smokers vs. never-smokers (odds ratio 1.17 in both analyses) and according to the Fagerström index of nicotine addiction. In the analysis stratified by gender this association was only found in females. Our data provide further evidence that variations in CHRM2 may be associated with the genetic risk of addiction in general or with certain personality traits that predispose to the development of addiction. Alternatively, variations in CHRM2 could modulate presynaptic auto-regulation in cholinergic systems and may thereby affect an individual's response to nicotine more specifically.

The value of pronuclear scoring for the success of IVF and ICSI-cycles.

BACKGROUND: Pronuclear scoring helps to identify good quality embryos already at the pronuclear stage. There are no data available, however, to demonstrate whether patients benefit from a higher pregnancy rate after pronuclear scoring. METHODS: In a retrospective, matched cohort study 338 cycles in which patients chose to score their oocytes at the pronuclear stage (scoring group) were compared with 338 cycles without scoring (control group). The cycles were matched for maternal age, number of previous IVF and ICSI cycles, cryopreservation (yes/no) and diagnosis of primary infertility. RESULTS: The pregnancy rate was not significantly different between the scoring group and the control group (24.0 vs. 21.0%, NS) in spite of more cycles with grade A embryos and a higher number of embryos transferred. The presence of a Z1 pronuclear oocyte was found to be associated with the retrieval of more oocytes, a higher fertilization rate and more grade A embryos, as well as a non-significant increase in pregnancy rates (25.1 vs. 18.8%). CONCLUSIONS: Benefit from pronuclear scoring seems to be small. Apparently, experienced biologists are able to select "good-quality" pronuclear oocytes in the same way they would do after scoring. However, the results might be biased by differences between the groups.

[Optimisation of possible success in an IVF program]. / Optimierung der Erfolgsaussichten in einem IVF-Programm.

The success of an IVF (in vitro fertilisation) programme is mainly dependent an the quality of the IVF laboratory. Beside this the quality of ovarian stimulation play another, but not as important role. In the 4 (th) quarter of 2003 we have changed the culture media for oocytes and embryos in the IVF laboratory of ENDOKRINOLOGIKUM Hamburg from simple to complex media (G-1 version 3). As protein source we used HSA-solution. Before embryo transfer equilibration for 1 hour in EmbryoGlue was performed, which contains hyaluran. Hyaluran is said to improve implantation rates by different ways. The media were bought from Vitrolife Schweden AB (Kungsbacka, Schweden) via a German distributor. These data were compared to those of two previous 3-month-periods (3rd quarter 2003 und 4th quarter 2002). The study design was prospective, with two historical control groups. In the three study periods 255, 343 and 503 patients were treated by either conventional IVF or ICSI (intracytoplasmic sperm injection). The cohorts were comparable regarding their anamnestic data. The number of patients treated which the GnRH antagonist cetrorelix (Cetrotide) significantly increased from 24.9 % to 49.5 % and 60.9 %. Under this protocol significantly less oocytes were retrieved (10.23 vs. 8.73 vs. 8.88), leading to slightly less embryos (1.94 vs. 1.91 vs. 1.85, not significant, n. s.). The cumulative embryo score significantly decreased from 28.58 to 24.10. It was significantly higher in the study cohort as compared to the two control cohorts (32.44). The clinical pregnancy rate significantly increased to 25.29 % in the study cohort as compared to the two historical control cohorts (15.02 % and 18.75 %). We could achieve a significant improvement in the success rates of our IVF program by switch from simple to more complex culture media in the IVF laboratory. The use of the GnRH antagonist protocol with cetrorelix (Cetrotide) lead to more comfort to the patients but did not influence the results.

A fusca gene homologue in mammalian tissues: Developmental regulation in the rat testes.

By differential screening of a rat pineal cDNA library we identified earlier a novel transcript having a 57% nucleotide homology and a 45% amino acid identity with a plant fusca-gene (fus6) to which a corresponding human sequence (gps1) has recently been reported. Expression of this mammalian fusca homologue (mfh) was seen in a variety of mammalian tissues, including kidney, pineal and retina, but it was particularly strong in the testes. Northern blot analysis demonstrated that the rat testicular mfh message increases markedly from day 28 onwards. Additionally, by in situ hybridization, mfh was localized primarily to the seminiferous tubules with a stage-dependent distribution pattern, a result which was confirmed by immunohistochemistry with antibodies raised against a synthetic MFH oligopeptide. Western blotting also revealed strong signals of the expected molecular weight in testicular extracts from several species. In view of its homology to fus6, a plant gene known to be involved in repressing photomorphogenesis in darkness, the conservation of mfh in mammals suggests a potential function for MFH in signaling pathways involved in the regulation of mammalian differentiation and development.