Frequent polymorphism of the mitochondrial DNA polymerase gamma gene (POLG) in patients with normal spermiograms and unexplained subfertility

BACKGROUND: Male fertility largely depends on the quality of sperm production, which may be affected by environmental and genetic factors. In this study, we explored a possible role of the polymerase gamma (POLG) gene polymorphism, recently reported to be associated with male infertility in some populations. METHODS: The polymorphic CAG repeat (usually 10 codons long) in the POLG gene was studied in 1298 male subjects: 429 patients with infertility/subfertility, and 869 controls (495 men from the general population with unknown fertility and 374 recent fathers). In all subjects, the POLG polymorphism was assessed in relation to their semen quality, and--in the fertile controls--with biological fecundity measured as waiting time-to-pregnancy (TTP) for the couples. In the patients lacking the common POLG allele, the outcome of the assisted reproductive techniques (ART) for the couples was evaluated. RESULTS: The absence of one (10/ not equal to 10) or both common POLG alleles (not equal to 10/not equal to 10) was more frequent among the subfertile patients than among fertile controls (P=0.021 and P=0.04 respectively). The estimated predictive value for infertility in a man homozygous for the POLG polymorphism was 15.5% (95% CI: 4.8-51%). There was a positive association with sperm concentration: 14.3% of the normospermic subfertile patients were homozygous for the absence of the common POLG allele (not equal to 10/not equal to 10), in comparison with 2.3% of unselected controls (P=0.001) and 0.9% of the fertile men (P=0.0001). No association with sperm motility, morphology and TTP was found. Spermatozoa of the three not equal to 10/not equal to 10 patients treated with IVF retained the ability to penetrate the egg, but the fertilization rate was low. Nine homozygous not equal to 10/ not equal to 10 patients were treated with ICSI, resulting in pregnancy in seven couples. CONCLUSIONS: The POLG gene polymorphism should be considered as a possible contributing factor in patients with unexplained subfertility and normal spermiograms. The oocyte penetration ability of sperm may be partially impaired in the not equal to 10/not equal to 10 patients but most of them can be successfully treated with ICSI.     

The role of size, sequence and haplotype in the stability of FRAXA and FRAXE alleles during transmission

Factors involved in the stability of trinucleotide repeats during transmission were studied in 139 families in which a full mutation, premutation or intermediate allele at either FRAXA or FRAXE was segregating. The transmission of alleles at FRAXA, FRAXE and four microsatellite loci were recorded for all individuals. Instability within the minimal and common ranges (0-40 repeats for FRAXA, 0-30 repeats for FRAXE) was extremely rare; only one example was observed, an increased in size at FRAXA from 29 to 39 repeats. Four FRAXA and three FRAXE alleles in the intermediate range (41-60) repeats for FRAXA, 31-60 for FRAXE) were unstably transmitted. Instability was more frequent for FRAXA intermediate alleles that had a tract of pure CGG greater than 37 although instability only occurred in two of 13 such transmissions: the changes observed were limited to only one or two repeats. Premutation FRAXA alleles over 100 repeats expanded to a full mutation during female transmission in 100% of cases, in agreement with other published series. There was no clear correlation between haplotype and probability of expansion of FRAXA premutations. Instability at FRAXA or FRAXE was more often observed in conjunction with a second instability at an independent locus suggesting genomic instability as a possible mechanism by which at least some FRAXA and FRAXE mutations arise.      

Semen quality and reproductive hormones before and after orchiectomy in men with testicular cancer

PURPOSE: We clarify the impact of removal of the tumor bearing testis on semen quality and reproductive hormones in men with testicular cancer. MATERIALS AND METHODS: Semen quality and levels of reproductive hormones were investigated in 48 men before and after orchiectomy for testicular cancer. Semen analysis was done in 35 of these men and hormone analyses were done in 47. The hormone data of patients with (14) or without (33) elevated values of human chorionic gonadotropin (HCG) were analyzed separately. RESULTS: Median sperm concentration and total sperm count decreased from 17 x 10(6)/ml. (range 0 to 117) and 39 x 10(6) (0 to 433), respectively, before to 7 x 10(6)/ml. (0 to 69) and 30 x 10(6) (0 to 200), respectively, after orchiectomy. After orchiectomy sperm concentration was decreased in 30 of 35 men (p = 0.001) and azoospermia developed in 3 (9%). In men without detectable HCG median follicle-stimulating hormone levels increased (p <0.001) from 5.7 IU/l. (range 0.01 to 30) before to 10.0 IU/l. (4.6 to 48) after orchiectomy in 33 of 33 patients. Median inhibin B significantly decreased (p = 0.003) from 108 pg./l. (range 60 to 193) before to 95 pg./l. (less than 20 to 141) after orchiectomy. Median luteinizing hormone increased significantly from 3.1 IU/l. (range 1.1 to 9.9) before to 5.2 IU/l. (2.1 to 27) after treatment (p <0.001). Testosterone and sex hormone-binding globulin did not change significantly after orchiectomy. Patients with detectable serum HCG before orchiectomy had a considerable increase in follicle-stimulating hormone after orchiectomy, and a concomitant decrease in testosterone and estradiol. CONCLUSIONS: Semen quality was poor at diagnosis and deteriorated further after orchiectomy compared with pretreatment values. Our findings indicate that in some patients the most appropriate time for cryopreservation of semen is before orchiectomy. Androgen production was maintained by increased luteinizing hormone stimulation after orchiectomy.     

Serum levels of growth hormone binding protein in children with normal and precocious puberty: relation to age, gender, body composition and gonadal steroids

AIM: To study the regulation of GHBP serum levels by gonadal steroids in normal and precocious puberty. STUDY PROTOCOL: We studied GHBP levels in relation to age, sex, pubertal maturation, body composition as well as to circulating IGF-I and gonadal steroid levels in 320 healthy children. Furthermore, we studied the regulation of circulating GHBP in 33 girls with central precocious puberty before and during gonadal suppression with GnRH agonist. METHODS: GHBP was determined by a time-resolved fluoroimmunoassay (GHBP TR-FIA) based on a commercially available immunoassay for GH, the DELFIA GH assay. RESULTS: In healthy children GHBP levels were significantly higher in normal girls compared with boys, and there was no significant increase in GHBP in puberty in both sexes. GHBP levels did not correlate with height (SDS), age, pubertal stage, IGF-I or testosterone/oestradiol levels in boys and girls, respectively. There were significant correlations between BMI and GHBP in boys and girls (R 2 = 0.14 and R 2 = 0.12, both P < 0.0001). Furthermore, GHBP correlated highly significantly with the percentage body fat, determined by BIA in 43 healthy girls (R 2 = 0. 40, P < 0.0001). GHBP levels were significantly higher in girls with central precocious puberty (CPP) (1.31 SDS (1.26), mean (SD)) compared to prepubertal controls (P < 0.0001), and above + 2 SD in 10 out of 33 patients. In girls with CPP, GHBP correlated inversely with oestradiol before treatment (R 2 = 0.26, P < 0.01) and there was a tendency towards a positive correlation with BMI (R 2 = 0.13, P = 0.078). By contrast, there were no signficant correlations between GHBP and IGF-I or height SDS. Gonadal suppression with GnRH agonist treatment caused a transient significant increase of 0.57 SD after 2 months of treatment (P < 0.001), but decreased to baseline levels hereafter. CONCLUSION: We conclude that in children, as in adults, body fat is the primary determinant for the circulating level of GHBP, and that the difference in body fat is probably the main factor for the higher levels of serum GHBP in girls compared with boys, as well as for the negative influence of testosterone levels in boys and of oestrogen levels in girls. The elevation in GHBP levels observed in girls with central precocious puberty is probably due their higher body fat content.     

The ratio between serum levels of insulin-like growth factor (IGF)-I and the IGF binding proteins (IGFBP-1, 2 and 3) decreases with age in healthy adults and is increased in acromegalic patients

OBJECTIVE Several in-vitro studies have suggested that the biological actions of IGF-I can be modified by the presence of specific IGF binding proteins. In man, the 24-hour serum levels of IGF-I and IGFBP-3 remain constant, but short-term changes in the IGF-l/IGFBP-3 ratio have been described following GH administration. Serum levels of IGF-I and IGFBP-3 decrease with age in normal adults and are elevated In active acromegaly due to excessive GH secretion. However, the Individual ratios between serum levels of IGF-I and IGFBP-3 in acromegalic and healthy adults have not been described previously. METHODS AND MATERIALS We studied this ratio In 198 healthy adults and In 56 acromegalic patients, grouped according to their serum GH levels (group I GH < 2mLU/l II GH 2–10mLU/l; III GH > 10mLU/l). In all subjects a single blood sample was drawn for IGF-I, IGF-II, IGFBP-1, IGFBP-2, IGFBP-3 and GH measurements by specific RIAs. In 38 of the patients a 24-hour urinary collection was performed for GH determination. RESULTS In healthy adults serum levels of IGF-I and IGFBP-3 decreased with Increasing age (r =?0.52 and r=?0.34, respectively, P< 0.0001). In addition, the molar IGF-l/IGFBP-3 ratio declined with increasing age (r =?0.44, P – 0.0001). In patients with acromegaly and high serum GH levels (group III), circulating IGF-I was increased 7–97 standard deviations (SDS) and IGFBP-3 was increased 4.20 SOS (P < 0.0001). Serum levels of IGF-II were normal in all three groups (588 ± 240μ/l) whereas IGFBP-1 and IGFBP-2 levels were low and IGFBP-2 levels decreased significantly with increasing serum GH levels (P < 0.0001). The molar IGF-l/IGFBP-3 ratio in the acromegalic patients was significantly higher than in the controls (P < 0.0001) and correlated significantly with urinary GH excretion (r = 0.67, P < 0.0001) as well as with serum GH levels (r = 0.73, P < 0.0001). CONCLUSION We demonstrated a decreasing molar IGF-l/IGFBP-3 ratio with increasing age in healthy adults and an increased ratio between serum IGF-I and IGFBP-3 levels in acromegalic patients. As IGF-II is normal and IGFBP-1 and IGFBP-2 are inversely correlated to the serum GH levels In the acromegalic patients, we speculate that the molar ratio between IGF-I and IGFBP-3 reflects free (biologically active) IGF-I and Is dependent on GH levels.     

Environmental chemicals and thyroid function

There is growing evidence that environmental chemicals can disrupt endocrine systems. Most evidence originates from studies on reproductive organs. However, there is also suspicion that thyroid homeostasis may be disrupted. Several groups of chemicals have potential for thyroid disruption. There is substantial evidence that polychlorinated biphenyls, dioxins and furans cause hypothyroidism in exposed animals and that environmentally occurring doses affect human thyroid homeostasis. Similarly, flame retardants reduce peripheral thyroid hormone (TH) levels in rodents, but human studies are scarce. Studies also indicate thyroid-disruptive properties of phthalates, but the effect of certain phthalates seems to be stimulative on TH production, contrary to most other groups of chemicals. Thyroid disruption may be caused by a variety of mechanisms, as different chemicals interfere with the hypothalamic-pituitary-thyroid axis at different levels. Mechanisms of action may involve the sodium-iodide symporter, thyroid peroxidase enzyme, receptors for THs or TSH, transport proteins or cellular uptake mechanisms. The peripheral metabolism of the THs can be affected through effects on iodothyronine deiodinases or hepatic enzymes. Even small changes in thyroid homeostasis may adversely affect human health, and especially fetal neurological development may be vulnerable. It is therefore urgent to clarify whether the animal data showing effects of chemicals on thyroid function can be extended to humans.     

Different modulation by histamine of IL-4 and interferon-gamma (IFN-γ) release according to the phenotype of human Th0, Th1 and Th2 clones

Histamine, an important inflammatory mediator in allergic diseases and asthma, has been reported to have modulator effects on T cells, suggesting that the bronchial microenvironment may regulate the function of resident T cells. We examined the effect of histamine on the release of the Th2-associated cytokines IL-4 and IL-5 and the Th1-associated cytokine IFN-γ by 30 CD4⁺ T cell clones from peripheral blood or bronchial biopsy of one atopic subject. Based on the IL-4/IFN-γ ratio, the clones were ascribed to the Th2 (ratio >1), Th0 (ratio 0.1 and 1) or Th1 (ratio <0.1) phenotype. Histamine inhibited IFN-γ production by Th1-like cells (P<0.02, Kruskall–Wallis), especially from bronchial biopsy, but had no effect on IL-4 release. Regarding Th0 clones, histamine inhibited IL-4 production (P<0.02) in a dose-dependent manner and slightly inhibited IFN-γ production, but had no effect on Th2-like cells. Histamine had a heterogeneous and insignificant effect on IL-5 production. The H₂-receptor antagonist ranitidine completely reversed the inhibition of IL-4 and IFN-γ production, whereas the agonist dimaprit mimicked this effect. In contrast, H₁- and H₃-receptor agonists and antagonists had no significant effect. These data demonstrate that histamine has different effects on IL-4 and IFN-γ release by T helper cells according to their phenotype via H₂-receptors. This study extends the immunomodulatory effects of histamine which may contribute to the perpetuation of airway inflammation in asthma.     

A study of finger lengths, semen quality and sex hormones in 360 young men from the general Danish population

BACKGROUND: It has been suggested that finger length may correlate with function or disorders of the male reproductive system. This is based on the HOXA and HOXD genes' common embryological control of finger development and differentiation of the genital bud. The objective of this study was to explore the association between the ratio of 2nd to 4th finger length (2D:4D ratio) and testis function in a sample of young Danish men from the general population. METHODS: Semen samples and finger measurements were obtained from a total of 360 young Danish men in addition to blood samples for sex hormone analysis to describe the possible association between 2D:4D and semen and sex-hormone parameters. RESULTS: A statistically significant inverse association with the 2D:4D was found only in relation to hormone levels of FSH in the group of young men with a 2D:4D >1 (P = 0.036) and a direct association with the total sperm count in the group of young men with a 2D:4D < or = 1 (P = 0.045). CONCLUSION: The statistically significant results may be 'false positives' (type I error) rather than representing true associations. This relatively large study of young, normal Danish men shows no reliable association between 2D:4D finger ratio and testicular function. Measurements of finger lengths do not have the power to predict the testicular function of adult men.