Implications of in-vitro fertilisation

The British government seems to be coming to accept the need for a full-scale inquiry into the implications of in vitro fertilization and related technological developments, including embryo transfer, AID, sperm banking, surrogate motherhood, and cloning. Health Under Secretary Geoffrey Finsberg, speaking to a small group of members of Parliament convened at the initiative of Labour member Leo Abse, said that such an inquiry will require careful planning and will have to involve nonmedical experts.     

Incidence of retinoblastoma in children born after in-vitro fertilisation

Every year, 3000 women in the Netherlands are treated with in-vitro fertilisation (IVF), and results from studies suggest that the offspring of these women do not have a heightened risk of cancer. Between November, 2000, and February, 2002, we diagnosed retinoblastoma in five patients born after IVF. To calculate the relative risk of the disease, we assumed that the proportion of children conceived by IVF in the Netherlands is between 1.0 and 1.5%, and that the five patients who we diagnosed with the disease represent all new cases in the Netherlands during that period. Relative risks for retinoblastoma were significantly raised (7.2 [95% CI 2.4-17.0], and 4.9 [1.6-11.3], for 1% and 1.5% rates, respectively). This possible association of an increased risk of retinoblastoma in a population-based study needs to be established.     

West Germany: strict rules for in-vitro fertilisation and embryo transfer

A nearly unanimous resolution was produced at the Deutscher Arztetag annual meeting, calling for the incorporation of standards for in vitro fertilization (IVF) and embryo transfer procedures into the official rules of professional conduct. The standards should specify that such procedures will be limited to the treatment of impaired fertility. Use of "lease mothers" is judged unacceptable. Extracorporally generated embryos should be implanted and not used for research except to improve the method of treatment or to identify a defective embryo. Physicians are urged to consult ethics commissions before participation in clinical or laboratory research involving IVF.     

Use of in-vitro fertilisation embryos cryopreserved for 5 years or more

Human embryos cryopreserved after in-vitro fertilisation can be stored initially for 5 years, and the storage period may be extended to a maximum of 10 years. Of 1344 embryos cryopreserved between 1988 and 1994 at two centres in Manchester, 67% (904 embryos) have had to be destroyed at the end of the first 5-year interval, even if the couples involved remain childless.     

Human in-vitro fertilisation and embryo transfer: recommendations to European Medical Research Councils

The text is presented of seven recommendations on the funding of research on in vitro fertilization and embryo transfer. The recommendations state that the technology is an "ethically acceptable method to overcome infertility" and urge support of related research. Seven priority areas of research are identified. Ova fertilized for a therapeutic purpose but no longer needed may be used for research if the informed consent of donors is obtained. National registers documenting attempts to induce pregnancy by IVF/ET and recording all resulting children are considered essential. Additional stipulations requested by the Medical Research Council of Norway are appended. [A correction in a later issue of Lancet (1983 Nov 26; 2(8361): 1264) notes the inadvertent omission of the crucial word "not" from the last sentence of the recommendation on use of gametes and embryos in research.]     

B族维生素在雄性小鼠高尿酸血症中的作用

目的研究B族维生素对高尿酸血症小鼠血尿酸水平的影响及其对高尿酸血症引起的内皮功能紊乱的作用。方法 SPF级昆明雄性小鼠63只,按体质量完全随机分成6组,A、B、C、D、E和F组。A组蒸馏水处理作为对照组,B组酵母膏+乙胺丁醇混合液灌胃处理建立小鼠高尿酸血症模型作为对照组;其余4组除建立模型外,还需在C组小鼠灌胃液中加入别嘌呤醇片,在D、E和F组中分别加入低、中、高剂量的叶酸+维生素B6+维生素B12混合溶液。3周后取血测定小鼠血尿酸水平及血清一氧化氮值。结果 3周后,6组小鼠的血清尿酸水平差异有统计学意义(F=14.7469,P<0.05)。与B组比较,D、E和F组小鼠的血清尿酸水平均能在一定程度上有所降低,且差异有统计学意义[D组(217.38±74.99)μmol/L,E组(228.19±65.25)μmol/L,F组(174.48±34.60)μmol/L比B组(302.93±56.99)μmol/L,均为P<0.05]。其中F组降低更显著,但其降低效果均低于C组[C组(105.52±49.32)μmol/L比F组(174.48±34.60)μmol/L,P<0.05]。6组小鼠的血清一氧化氮水平差异有统计学意义(F=7.0499,P<0.05)。与B组比较,E组和F组的血清一氧化氮水平均升高[E组(16.52±10.95)μmol/L,F组(18.63±10.77)μmol/L比B组(2.51±3.89)μmol/L,P<0.05],且与C组比较,F组升高更明显[C组(9.35±5.65)μmol/L比F组(18.63±10.77)μmol/L,P<0.05]。血清一氧化氮水平与尿酸水平呈负直线相关(r=-0.278,P<0.05)。结论叶酸、维生素B12及维生素B6可呈剂量依赖性降低高尿酸血症小鼠的血尿酸水平;同时较大剂量的B族维生素能够在一定程度上升高血清一氧化氮水平。     

不同种类B族维生素降低尿酸和保护血管内皮作用探讨

目的对比分析各类B族维生素对高尿酸血症(HUA)动物模型血清尿酸水平的降低作用和血管内皮功能的保护作用。方法选择SPF级雄性昆明种小鼠77只,按体质量随机分为6组,对照组12只,别嘌呤醇组13只,维生素B_2组13只,维生素B_6组13只,维生素B_(12)组13只,叶酸组13只。测定各组小鼠血清尿酸和NO水平;免疫组织化学法检测NF-κB和血管内皮细胞黏附因子1(VCAM-1)蛋白的表达。结果别嘌呤醇组、维生素B_2组、维生素B_6组、维生素B_(12)组及叶酸组血清尿酸水平及NF-κB和VCAM-1表达强度明显低于对照组,血清NO水平明显高于对照组(P0.01)。与别嘌呤醇组比较,维生素B_2组尿酸水平明显升高,NO水平明显降低,而维生素B_(12)组NO水平明显升高(P0.01)。各组小鼠主动脉内膜形态和血管壁结构未发生改变。对照组主动脉内膜NF-κB和VCAM-1可见连续阳性表达,其他各组表达均有不同程度的减弱。维生素B_2组NF-κB和VCAM-1表达强度明显高于别嘌呤醇组,维生素B_6组、维生素B_(12)组及叶酸组NF-κB和VCAM-1表达强度明显低于别嘌呤醇组(P0.05,P0.01)。结论各类B族维生素均可有效降低HUA小鼠血清尿酸水平,同时显著提升血清NO水平。各类B族维生素均可不同程度地抑制HUA小鼠主动脉内膜NF-κB和VCAM-1表达。     

Effect of supplementation with folic acid and B vitamins on cardiovascular outcomes: a meta-analysis of randomised controlled trials

Background

There is an increasing amount of data over the effect of folic acid and B vitamins (vitamin B6 and B12) on cardiovascular disease, but whether supplementation with folic acid and B vitamins can reduce the risk of cardiovascular disease among middle-aged and elderly patients remains unclear. We conducted this meta-analysis to assess the efficacy of folic acid supplementation in the prevention of cardiovascular disease.