Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization

The development and application of fluorescence in-situ hybridization (FISH) has opened the way for comprehensive studies on numerical chromosome abnormalities in human spermatozoa. FISH can be rapidly applied to large numbers of spermatozoa and thus overcomes the major limitation of karyotyping spermatozoa after penetration of zona-free hamster oocytes. The simultaneous hybridization of two or more chromosome-specific probes to spermatozoa and subsequent detection of the bound probes using different fluorescent detection systems enables two or more chromosomes to be localized simultaneously in the same spermatozoon and provides a technique for undertaking reasonable estimates of aneuploidy. The most commonly used probes are those which bind to the centromeric region of specific chromosomes. Most studies to date have concentrated on estimating aneuploidy in spermatozoa from normospermic men, although reports are beginning to appear on aneuploidy in spermatozoa from subfertile and infertile men. Multi- probe FISH studies have generally reported disomy (hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary evidence that some chromosomes such as X, Y and 21 are predisposed towards higher rates of non-disjunction during spermatogenesis. There are also suggestions of inter-donor variability in aneuploidy frequencies for specific chromosomes, although this requires confirmation in larger studies. While FISH is clearly a powerful technique that has many applications in reproductive medicine, it must also be realized that it does have limitations and the technology itself is still evolving and has yet to be fully validated on spermatozoa.      

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.      

Alteration in the hypothalamic-pituitary-ovarian axis in depressed women

BACKGROUND: Stress and corticotropin-releasing hormone inhibit the reproductive axis. We hypothesized that reproductive axis hormone secretion, particularly luteinizing hormone secretion, is inhibited in women with depression, similar to what has been observed to be caused by stress in numerous species. METHODS: Blood samples were collected every 10 minutes for 12 hours in 25 untreated premenopausal women with depression and 25 nondepressed women who were matched by age and menstrual cycle day. Samples were assayed for luteinizing hormone, follicle-stimulating hormone, estradiol, and progesterone. RESULTS: The mean plasma estradiol level was 30% lower in the follicular phase in women with depression than in their matched controls: 191 + 136 vs 261 + 169 pmol/L (52 + 37 vs 71 + 46 pg/mL). The half-life of luteinizing hormone was significantly shorter in women with depression than in their matched controls during both the follicular (22% shorter) and luteal (15% shorter) phases. CONCLUSIONS: The blood levels of reproductive hormones were mostly normal in women with depression, but the blood level of estradiol was significantly lower. Estradiol is known to affect a number of neurotransmitter systems in the brain. Arch Gen Psychiatry. 2000;57:1157-1162.     

A prospective study of methylenetetrahydrofolate reductase and methionine synthase gene polymorphisms, and risk of colorectal adenoma

We examined the relationship between a functional polymorphism (667C-- >T, ala-->val) of the methylenetetrahydrofolate reductase gene (MTHFR) and the risk of colorectal adenomas in the prospective Nurses' Health Study. Among 257 incident polyp cases and 713 controls, the MTHFR val/val polymorphism [relative risk (RR) = 1.35, 95% confidence interval (CI) 0.84-2.17] was not significantly associated with risk of adenomas. This lack of association was observed for both small (RR = 1.36, 95% CI 0.76-2.45) and large (RR = 1.32, 95% CI 0.66-2.66) adenomas. Furthermore, there was no significant interaction between this polymorphism and consumption of either folate, methionine or alcohol. We also examined the relationship of a newly identified polymorphism (asp919gly) of the methionine synthase gene (MS) with the risk of colorectal adenomas in the same population. The MS gly/gly polymorphism was also not significantly associated with risk of colorectal adenomas (RR = 0.66, 95% CI 0.26-1.70). These results, which need to be confirmed in other studies, suggest that the MTHFR val/val polymorphism, which has been previously inversely associated with risk of colorectal cancer, plays a role only in a late stage (adenoma-- >carcinoma) of colorectal tumorigenesis, and/or may protect against malignant transformation in the subset of benign adenomas, which may progress to malignancy.      

Bevacizumab--current status and future directions.

Angiogenesis is crucial to tumour initiation, survival and metastasis. Vascular endothelial growth factor (VEGF) is one of the most important pro-angiogenic factors in cancer development. Bevacizumab (a humanised monoclonal antibody against VEGF) has a reasonable safety profile and proven efficacy in a phase III trial in advanced colorectal cancer. Efficacy of Bevacizumab also looks promising in non small cell lung cancer, renal cancer and a variety of other solid tumours. Questions still surround optimal dosing and the appropriate selection of patients who are most likely to benefit. Future trials will address these questions and provide further translational insights.