The number of CAG and GGN triplet repeats in the Androgen Receptor gene exert combinatorial effect on hormonal and sperm parameters in young men.

Androgen receptor (AR) is a transcription factor that is activated upon binding to testosterone (T) and is implicated in regulating the expression of reproduction-related genes. The human AR gene (Xq11-12) spans 186,588 bp and eight exons. N-terminal transactivation domain of the encoded AR protein harbours two polymorphic stretches of identical amino acids, a polyglutamine tract (encoded by 8-37 CAG-repeats) and a polyglycine tract (encoded by 10-30 GGN-repeats). We set forward to analyse independent and combinatory effects of the length of these repetitive tracts on male reproductive hormones, testicular and sperm parameters in a population-based cohort of Baltic young men (n = 974; aged 20.1 ± 2.1 years). We designed an assay to amplify and detect simultaneously the variants of both polymorphic repeats. The study revealed that elongated AR CAG tract was associated with lower FSH (linear regression: p = 0.0002, effect per repeat -0.056 IU/L). As a novel finding, the carriers of GGN-stretch with ≥24 repeats showed a trend for decreased sperm concentration (p = 0.027). Although neither of the variants exhibited an isolated effect on circulating T, their allelic combinations modulated serum T levels, as well as sperm concentration. The lowest T was measured for men carrying the AR gene with long CAG (n ≥ 25) and short GGN (n ≤ 21) repeat tracts (mean 18.8 vs. 25.5-28.6 nmol/L for the other AR variants, p = 0.017). The lowest sperm concentration was detected among individuals with both elongated repetitive stretches (CAG, n ≥ 25 and GGN, n ≥ 24; mean 49.0 vs. 68.4-72.1 mill/mL for the other variants; p = 0.00059). The innovative study design enabled to clearly demonstrate a combinatory impact of CAG and GGN repeat lengths at male reproductive parameters. As AR regulates transcription of over 900 genes in many tissues and organs, the combinatory effects of these common repeat-length variants on male physiology in the wider context and across lifetime are still to be assessed.

'Carriers of variant luteinizing hormone (V-LH) among 1593 Baltic men have significantly higher serum LH'.

Luteinizing hormone (LH) is a pituitary heterodimeric glycoprotein essential in male and female reproduction. Its functional polymorphic variant (V-LH) is determined by two missense mutations (rs1800447, A/G, Trp8Arg; rs34349826, A/G, Ile15Thr) in the LH ß-subunit encoding gene (LHB; 19q13.3; 1111 bp; 3 exons). Among women, V-LH has been associated with higher circulating LH and reduced fertility, but the knowledge of its effect on male reproductive parameters has been inconclusive. The objective of this study was to assess the effect of V-LH on hormonal, seminal and testicular parameters in the Baltic young men cohort (n = 986; age: 20.1 ± 2.1 years) and Estonian idiopathic infertility patients (n = 607; 35.1 ± 5.9 years). V-LH was detected by genotyping of the underlying DNA polymorphisms using PCR-RFLP combined with resequencing of a random subset of subjects. Genetic associations were tested using linear regression under additive model and results were combined in meta-analysis. No significant difference was detected between young men and infertility patients for the V-LH allele frequency (11.0 vs. 9.3%, respectively). V-LH was associated with higher serum LH in both, the young men cohort (p = 0.022, allelic effect = 0.26 IU/L) and the idiopathic infertility group (p = 0.008, effect = 0.59 IU/L). In meta-analysis, the statistical significance was enhanced (p = 0.0007, resistant to Bonferroni correction for multiple testing; effect = 0.33 IU/L). The detected significant association of V-LH with increased serum LH remained unchanged after additional adjustment for the SNPs previously demonstrated to affect LH levels (FSHB -211G/T, FSHR Asn680Ser, FSHR -29A/G). Additionally, a suggestive trend for association with reduced testicular volume was observed among young men, and with lower serum FSH among infertility patients. The V-LH carrier status did not affect sperm parameters and other circulating reproductive hormones. For the first time, we show a conclusive contribution of V-LH to the natural variance in male serum LH levels. Its downstream clinical consequences are still to be learned.

Study in 1790 Baltic men: FSHR Asn680Ser polymorphism affects total testes volume.

Follicle-stimulating hormone receptor (FSHR) contains two common linked polymorphisms, Thr307Ala (rs6165) and Asn680Ser (rs6166), shown to modulate ovarian function in women. The effect on male fertility and reproductive parameters has been inconclusive. We studied FSHR Asn680Ser polymorphism in a large study group (n = 1790) from the Baltic countries. The population-based Baltic male cohort (Estonians, Latvians, Lithuanians; n = 1052) and Estonian oligo-/azoospermic (sperm concentration <20 × 10(6) /mL) idiopathic infertile patients (n = 738) were genotyped for the FSHR Asn680Ser using PCR-RFLP. Genetic associations were tested using linear regression under additive model and results were combined in meta-analysis. No statistical difference was detected in allelic distribution of the FSHR Asn680Ser between the Baltic cohort and Estonian male infertility group. A consistent significant association was detected between the FSHR Ser680 allele and lower total testes volume in both, the Baltic cohort (p = 0.010, effect = -1.16 mL) and Estonian idiopathic infertility group (p = 0.007, effect = -1.77 mL). In meta-analysis, the statistical significance was enhanced (p = 0.000066, effect = -1.40 mL). Meta-analysis supported further associations with moderate effect between the FSHR Ser680 variant and higher serum FSH (p = 0.072), lower Inhibin B (p = 0.037) and total testosterone (p = 0.034). No statistically significant associations were identified with serum LH and estradiol, and sperm parameters. In conclusion, the study in 1790 Baltic men shows statistically highly significant association of the FSHR Asn680Ser with total testes volume and supportive association with serum reproductive hormone levels indicative to the functional effect of the alternative FSHR variants on male reproductive physiology.

Haplotype structure of FSHB, the beta-subunit gene for fertility-associated follicle-stimulating hormone: possible influence of balancing selection.

Follicle-stimulating hormone (FSH) is essential for human reproduction. The unique functions of this hormone are provided by the FSH receptor-binding beta-subunit encoded by the FSHB gene. Resequencing and genotyping of FSHB in three European, two Asian and one African population, as well as in the great apes (chimpanzee, gorilla, orangutan), revealed low diversity and significant excess of polymorphisms with intermediate frequency alleles. Statistical tests for FSHB showed deviations from neutrality in all populations suggesting a possible effect of balancing selection. Two core haplotypes were identified (carried by 76-96.6% of each population's sample), the sequences of which are clearly separated from each other. As fertility most directly affects an organism's fitness, the carriers of these haplotypes have apparently had more success in human history to contribute to the next generation. There is a preliminary observation suggesting that the second most frequent FSHB haplotype may be associated with rapid conception success in females. Interestingly, the same haplotype is related to an ancestral FSHB variant shared with the ancestor of the great apes. The determination of the functional consequence of the two core FSHB variants may have implications for understanding and regulating human fertility, as well as in assisting infertility treatments.

No differences in performance on test of working memory and executive functioning between healthy elderly postmenopausal women using or not using hormone therapy.

BACKGROUND: On average, ovarian function ceases at the age of 52 years so that estrogen (E) levels are chronically low following the menopause. Numerous studies have found that hormone therapy (HT) helps to protect verbal memory, a hippocampal function. Estrogen receptors are also found in the prefrontal cortex (PFC), suggesting that estrogen may modulate executive and working memory functions, both mediated by the PFC. The possible role of progesterone (P) on executive functions and working memory is unknown. OBJECTIVE: To examine the relationship between neuropsychological performance, age of initiation of HT, and duration of HT use. METHOD: In this cross-sectional study, the neuropsychological performance of 37 postmenopausal women (mean age, 65 years) who used either estrogen-only or sequential E + P (E-alone group)(n = 22) or E + P continuously (n = 15) was compared to that of 28 healthy postmenopausal women matched for age and education who had never used HT. It was hypothesized that the E-only users would perform better then the E + P and the never-users on neuropsychological tests of verbal memory, executive function and working memory. RESULTS: Results showed only minor between-group differences on working memory scores such that the E + P users were slowest to generate a response on the N-Back test of working memory. No group differences on tests of executive functions were found. CONCLUSION: There was no relationship between neuropsychological performance, age of initiation of HT, or duration of HT use.

Possible causes of chromosome instability: comparison of chromosomal abnormalities in cancer cell lines with mutations in BRCA1, BRCA2, CHK2 and BUB1.

A large proportion of epithelial cancers show the chromosome-instability phenotype, in which they have many chromosome abnormalities. This is thought to be the result of mutations that disrupt chromosome maintenance, but the causative mutations are not known. We identified cell lines known to have mutations that might cause chromosome instability, and examined their karyotypes. Two cell lines, the breast cancer line HCC1937 and the pancreatic cancer line CAPAN-1, that have mutations respectively in BRCA1 and BRCA2, had very abnormal karyotypes, with many structural and numerical chromosome changes and substantial variation between metaphases. However, two colorectal cancer lines with mutations in BUB1, a spindle checkpoint protein involved in chromosome segregation, had rather simple near-tetraploid karyotypes, with minimal loss or gain of chromosomes other than the endoreduplication event, and minimal structural change. Apart from tetraploidy, these karyotypes were typical of colorectal lines considered to be chromosomally stable. Two lines derived from the same tumour, DLD-1 and HCT-15, with bi-allelic mutation of CHK2, had karyotypes that were typical of near-diploid colorectal lines considered chromosomally stable. The karyotypes observed supported the proposed role for BRCA1 and BRCA2 mutations in chromosomal instability, but showed that the tested mutations in BUB1 and CHK2 did not result in karyotypes that would have been predicted if they were sufficient for chromosomal instability.

Spontaneous and X-ray-induced chromosomal aberrations in Werner syndrome cells detected by FISH using chromosome-specific painting probes.

Werner syndrome (WS) is a rare autosomal disorder characterized by premature aging exhibiting chromosome instability and predisposition to cancer. Cells derived from WS patients show a variety of constitutionally stable chromosomal aberrations as detected by conventional chromosome banding techniques. We have employed the fluorescence in situ hybridization (FISH) technique using painting probes for 12 different chromosomes to detect stable chromosome exchanges in three WS cell lines and three control cell lines. WS cell lines showed increased frequencies of both stable and unstable chromosome aberrations detected by FISH and Giemsa staining, respectively. One WS lymphoblastoid cell line (KO375) had a 5/12 translocation in all the cells and approximately 60% of the cells had an additional translocated chromosome 12. A high frequency of aneuploid cells was found in all the WS cell lines studied. Though WS cells are known to be chromosomally unstable, unlike other chromosome instability syndromes they are not sensitive to mutagenic agents. We studied the frequencies of X-ray-induced chromosomal aberrations in two WS cell lines and found an approximately 60% increase in the frequencies of fragments and no consistent increase in the frequencies of exchanges.

Induction and persistence of chromosomal exchanges in mouse bone marrow cells following whole-body exposure to X-rays.

PURPOSE: To investigate the induction and persistence of chromosome aberrations in mouse bone marrow cells after X-ray exposure and to detect differential involvement of individual chromosomes in translocations. MATERIALS AND METHODS: Male and female Swiss mice were exposed to 1 and 3 Gy of X-rays. Chromosome aberrations in bone marrow cells were analysed at 1, 7, 21 and 100 days following irradiation by means of fluorescence in situ hybridization (FISH) with mouse chromosome-specific DNA libraries (#1,13; #2,8; #6,15 and X,Y). In total, 38% of mouse genome was painted and examined. RESULTS: Pooled data indicate that the frequencies of dicentrics and fragments decreased with time and reached to the control level at day 21 after exposure. Following exposure to 1 Gy of X-rays, the frequencies of translocations were not significantly lower between days 7 and 100 than observed at day 1. However, the frequencies of translocations for the 3 Gy group were significantly (about 40%) lower at day 7, then remained constant up to day 100. After exposure to 3Gy of X-rays, the frequencies of non-reciprocal translocations decreased with time, whereas reciprocal translocations between days 7 and 100 were not significantly less frequent than at day 1. A comparison of observed and expected numbers of translocations involving individual chromosomes showed that at day 1 after irradiation, distribution of X-ray-induced translocations among the painted chromosomes was proportional to their DNA content. However, at day 100 after exposure, the observed translocations involving chromosome 2 were more frequent than expected, those involving chromosomes 8 and 15 were less frequent than expected, while chromosomes 1, 6, X and Y were involved as frequently as expected. CONCLUSION: Among induced translocations, non-reciprocal translocations are relatively unstable, especially after exposure to high-dose X-rays. While the initial distribution of X-ray-induced translocations is proportional among the painted chromosomes, the persistence of these translocations is heterogeneous.

Comparison of AluI-induced frequencies of dicentrics and translocations in human lymphocytes by chromosome painting.

It has been shown repeatedly that following irradiation of human lymphocytes in the G0 stage, more translocations are induced than dicentrics. To check the role of DNA double-strand breaks (DSB) alone for the induction of symmetrical and asymmetrical chromosome aberrations, the frequencies of induced exchange aberrations by the restriction enzyme AluI were analyzed. The enzyme was introduced into cells using the pellet pipetting technique. Frequencies of induced translocations and dicentrics were determined using a chromosome painting assay with chromosome-specific DNA libraries for chromosomes 1, 4 and X (representing 16.8% of the human genome). The number of translocations detected was approximately 3-fold higher than the number of dicentrics, indicating that the increased frequency of translocations compared with dicentrics found in irradiated human lymphocytes does not result from DNA lesions other than DSB but from differential processing of DSB.

Relative involvement of chromosome #21 in radiation induced exchange aberrations in lymphocytes of Down syndrome patients.

It is not yet resolved as to what type of DNA double strand break repair operates in G0 lymphocytes. We have employed Down syndrome (DS) lymphocytes with three copies of chromosome #21 to answer the question whether the presence of three copies reduces the frequency of exchange aberrations involving this chromosome in comparison to normal cells with two copies of #21. Peripheral blood lymphocytes from three DS patients and two normal individuals were X-irradiated with 1 and 3 Gy. The frequencies of unstable aberrations were found to be higher in DS lymphocytes than normal lymphocytes after 3 Gy of X-rays. FISH studies employing chromosome specific DNA libraries for chromosomes #21 and #22 indicated that the frequencies of exchange aberrations per chromosome are similar in both disomic and trisomic condition. This indicates that the presence of an extra copy of chromosome #21 does not alter the yield, suggesting that homologous recombination does not play a major role in the repair of DNA strand breaks in human G0 lymphocytes.

Frequencies and types of exchange aberrations induced by X-rays and neutrons in Chinese hamster splenocytes detected by FISH using chromosome-specific DNA libraries.

PURPOSE: To estimate the frequencies of radiation- (low and high LET) induced chromosome aberrations in Chinese hamster splenocytes by two-colour fluorescence in situ hybridization using DNA painting probes specific for chromosomes 2, 3, 8, X and Y and to determine (1) the ratio of radiation-induced translocations and dicentrics; (2) the spectrum of exchange aberrations induced by X-rays and neutrons; and (3) the relative involvement of the different chromosomes in the formation of aberrations. MATERIALS AND METHODS: Isolated splenocytes from the Chinese hamster were irradiated in vitro with different doses of 200 kV X-rays (0.75, 1.5, 3.0 Gy) and 1 MeV fast neutrons (0.25, 0.5, 1.0 Gy). Conventional analysis of chromosome aberrations was carried out in Giemsa-stained preparations. Chromosome aberrations involving chromosomes 2, 3, 8, X and Y were analysed in first division metaphases using two-colour FISH. RESULTS: The results indicate that when all types of translocations are taken into account both X-rays and neutrons induce more translocations than dicentrics, the ratio between the two types of exchanges being 1.4 and 1.8 respectively. The ratio of 'apparently simple' reciprocal translocations and reciprocal complete dicentrics was close to 1 for both types of radiation. The RBE of neutrons for induction of exchanges was found to be between 5 and 8. Neutron irradiation was more efficient at inducing insertions. Among the chromosomes studied, an increased involvement was observed for chromosome 8 in dicentrics and translocations than that expected on the basis of its chromosome length. The high content of interstitial telomeric sequences in chromosome 8 may be responsible for the observed sensitivity of this chromosome. CONCLUSIONS: The results obtained in this study indicate that: (1) more translocations are found than dicentrics; (2) heterogeneity exists among Chinese hamster chromosomes for involvement in radiation-induced exchanges; (3) the spectrum and distribution of exchange aberrations are different between X-rays and neutrons; and (4) the relative frequencies of insertions could be used as a 'fingerprint' for exposure to high LET radiation.

137Cesium-induced chromosome aberrations analyzed by fluorescence in situ hybridization: eight years follow up of the Goiânia radiation accident victims.

The radiation accident in focus here occurred in a section of Goiânia (Brazil) where more than a hundred individuals were contaminated with 137Cesium on September 1987. In order to estimate the absorbed radiation doses, initial frequencies of dicentrics and rings were determined in 129 victims [A.T. Ramalho, PhD Thesis, Subsidios a tecnica de dosimetria citogenetica gerados a partir da analise de resultados obtidos com o acidente radiologico de Goiânia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 1992]. We have followed some of these victims cytogenetically over the years seeking for parameters that could be used as basis for retrospective radiation dosimetry. Our data on translocation frequencies obtained by fluorescence in situ hybridization (FISH) could be directly compared to the baseline frequencies of dicentrics available for those same victims. Our results provided valuable information on how precise these estimates are. The frequencies of translocations observed years after the radiation exposure were two to three times lower than the initial dicentrics frequencies, the differences being larger at higher doses (>1 Gy). The accuracy of such dose estimates might be increased by scoring sufficient amount of cells. However, factors such as the persistence of translocation carrying lymphocytes, translocation levels not proportional to chromosome size, and inter-individual variation reduce the precision of these estimates.

Enhanced optical limiting in derivatized fullerenes.

We have observed enhanced optical limiting behavior in solutions of a derivatized fullerene (phenyl-C(61)-butyric acid cholesteryl ester) from 532 to 700 nm. Transient absorption measurements determined the spectral and temporal regions of interest for optical limiting in C(60) and in C(60) derivatives that are due to a reverse saturable absorption mechanism and predicted enhanced limiting at longer wavelengths. Intensity-dependent transmission measurements made at several wavelengths confirmed these results. The increased solubility and the broadened ground-state absorption of the functionalized C(60) make it suitable for use as an optical limiter in the red and the near infrared.

Mitotic and meiotic detection of radiation-induced translocations in mouse stem cell spermatogonia using fluorescence in situ hybridization.

The efficiency of two methods of detection of translocations induced in mouse stem cell spermatogonia by X-ray doses of 2, 5 and 7 Gy was compared: classical multivalent analysis at diakinesis-metaphase I of meiosis and observation via fluorescence in situ hybridization analysis of mitotic or meiotic stages. Specific DNA libraries for chromosomes 1, 11 and 13 were used. The results obtained indicate that (a) chromosomes 1, 11 and 13 are more involved in multivalent formation than expected on the basis of DNA content and (b) if the mitotic FISH analysis data are corrected for the observed over-representation, the frequencies of induced translocations are similar to those recorded in the classical multivalent studies, suggesting equal scoring efficiencies in both systems.

X-ray induced translocations in bone marrow cells of scid and wild type mice detected by fluorescence in situ hybridization using mouse chromosome specific DNA libraries.

Radiation induced chromosomal aberrations in bone marrow cells of scid and normal mice were studied at different sampling times. Fluorescence in situ hybridization (FISH) with DNA libraries specific for chromosomes 1, 11 and 13 was applied to identify the stable types of chromosomal aberrations in addition to the unstable ones. The results obtained confirm earlier observations on stem cell spermatogonia in that, contrary to the situation in normal mice, only very low levels of translocations could be recovered from scid mice at relatively long sampling times (3 weeks). However, studies at a 24 h sampling period demonstrated substantial induction of translocations in scid mice. This suggests enhanced elimination of translocation carrying cells in scid mice during successive cell proliferation, possibly via falling apart of the translocation at the original points of exchange or due to lethal damage at the translocation break points.

X-ray-induced chromosomal aberrations and cell killing in somatic and germ cells of the scid mouse.

To characterize further the radiosensitivity of severe combined immunodeficiency (scid) mice, the induction of micronuclei (MN) in polychromatic erythrocytes as well as cell killing and translocation induction in stem cell spermatogonia was studied. Scid mice turned out to be clearly hypersensitive for X-ray-induced cell killing of both bonemarrow cells and spermatogonial stem cells. The frequencies of recorded micronuclei in polychromatic erythrocytes were comparable with that reported for the normal mouse, whereas the recovery of translocations was extremely low in the scid mouse. The dose-response relationship for induced translocations was bell shaped with a maximum of about 0.5% around doses of 0.5-1.5 Gy X-rays.

Recent developments in the assessment of chromosomal damage.

Ionizing radiation and restriction endonucleases are very efficient in inducing chromosomal aberrations (CAs). These aberrations are mainly consequences of misrepair of DNA double-strand breaks (DSBs). The fast repairing component of DSBs induced by ionizing radiation seems to be responsible for exchange aberration. Use of premature chromosome condensation technique in combination with DNA repair inhibitors such as ara A has given valuable information on the assessment of the frequencies of initial chromosome breaks and the kinetics of their repair following low LET radiation. The recently developed 'chromosome painting' technique using chromosome-specific libraries has also increased considerably the resolution of identifying and scoring of CAs. After low LET radiation, stable chromosome exchanges (translocations) are induced more frequently than unstable chromosome exchanges (dicentrics). Fluorescence in situ hybridization employing telomeric probe has made it possible to score efficiently exchange aberrations involving the acrocentric chromosomes of mouse. Chinese hamster cells have several intercalary telomeric sequences present in most of the chromosomes. These telomeric blocks have been found to be associated with chromosomal aberrations induced by restriction endonucleases and short wave UV and evidence has been obtained for apparent amplification of telomeric sequences at the break points.

Ecology of Staphylococcus aureus: comparative characterization of strains isolated from man, cattle and sheep in Bulgaria and in the GDR.

Staphylococcus aureus strains from man, cattle and sheep have been differentiated by biochemical tests and by phage typing. Strains from pathological material of human origin mostly belong to the host-specific variety hominis, strains from mastitis in cattle mostly belong to the host-specific variety bovis. However, there are also strains from cattle which cannot be allotted to one of the known host-specific varieties and also strains which belong to the host-specific variety hominis. Strains from mastitis in sheep clearly differ from strains of human and bovine origin; these strains are designated as variety ovis. The frequency distribution of the host-specific varieties in man, cattle and sheep is the same in Bulgaria and in the GDR.