Category Archives: Human Reproduction

BACKGROUND

Increased global industrial activity has exposed humans to a wide variety of chemical substances some of which, called ‘endocrine-disrupting chemicals’ (EDCs) or ‘endocrine disruptors’, can disrupt the endocrine system in the body. The ovarian follicle is a very fragile micro-environment where interactions between hormones, growth factors, the oocyte and its surrounding somatic cells are essential to generate a fully competent oocyte. In vitro experiments suggest that EDCs can disturb this finely tuned balance, but very scarse in vivo data are available to confirm this assumption. Therefore, we have investigated if the presence of EDCs in human follicular fluid is a risk factor for the developmental competence of an in vivo exposed oocyte. Furthermore, because of the limited access to human follicular fluid, we verified if follicular fluid contamination can be predicted based on EDC levels in serum.

METHODS

Follicular fluid (n = 40) and serum (n = 20) samples from women undergoing assisted reproductive technology (ART) were analyzed by means of gas chromatography combined with mass spectrometry to examine the presence of different EDCs, such as polychlorinated biphenyls, polybrominated diphenyl ethers and organochlorine pesticides. Statistical models were used to investigate the relation between the characteristics and ART results of the patients and the contamination status of their follicular fluid and to assess the capacity of serum samples to predict follicular fluid contamination.

RESULTS

Chlorinated biphenyl 153 (72 ± 44 and 201 ± 106 pg/ml) and p,p'-DDE (392 ± 348 and 622 ± 406 pg/ml) were the compounds found in the highest concentrations in follicular fluid and serum samples, respectively. A new variable principal component 1, representing the overall contamination status of the follicular fluid samples, is strongly associated with fertilization rate (P < 0.00001) and the proportion of high-quality embryos relative to the amount of retrieved oocytes (P < 0.05), even when the analysis is adjusted for age, estradiol concentration, BMI, fertilization procedure and male subfertility as explanatory variables. The strong correlations between the EDC concentrations in serum and follicular fluid (r ≥ 0.93) allowed us to build regression models, which accurately predict EDC concentrations in the follicular fluid based on serum samples.

CONCLUSIONS

An overall higher EDC contamination in the follicular micro-environment was associated with a decreased fertilization rate and consequently with a lower chance of an oocyte to develop into a high-quality embryo. In addition, EDC concentrations in serum were reliable predictors of the contamination status of the follicular micro-environment.

Source:
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BACKGROUND

Sperm chromatin is highly condensed and relatively resistant to chemical and physical treatments. The purpose of this study was to explore the highest temperature that sperm can tolerate and still produce live offspring.

METHODS

Mouse sperm were heated in a water bath at 50, 65, 80 or 95°C for 30 min before they were microinjected into mouse oocytes. Fertilization, embryo development and 1-cell embryo karyotypes were evaluated. Epigenetic reprogramming including DNA methylation and histone H3K4-trimethylation were evaluated by immunofluorescent staining.

RESULTS

The ability of mouse sperm to activate the egg after ICSI was heat sensitive; only 20% of eggs were activated by sperm that had been heated to 50°C and none was activated by sperm heated to 80°C. However, if eggs were activated artificially, mouse sperm subjected to 80°C for 30 min were able to produce live offspring, while 95°C treatment disabled sperm decondensation after ICSI. Once the heat-treated sperm nucleus had developed into a pronucleus, sperm chromatin was able to undergo normal active DNA demethylation and histone methylation. Aberrant chromosome rates increased from 16.3 to 100% when the temperature was raised from 50 to 95°C.

CONCLUSIONS

Heat treatment destroys integrity of sperm chromatin in a temperature-dependent manner. Eighty degree Celsius was the highest temperature that mouse sperm could withstand and still produce live offspring.

Source:
http://humrep.oxfordjournals.org/rss/current.xml

BACKGROUND

The progesterone-regulated glycoprotein glycodelin-A (GdA), secreted by the decidualized endometrium at high concentrations in primates, inhibits the maternal immune response against fetal antigens and thereby contributes to the tolerance of the semi-allogenic fetus during a normal pregnancy. Our earlier studies demonstrated the ability of GdA to induce an intrinsic apoptotic cascade in CD4⁺ T-lymphocytes and suppress the cytolytic effector function of CD8⁺ T-lymphocytes. In this report, we investigated further into the mechanism of action of GdA controlling perforin and granzyme B expression in CD8⁺ T-lymphocytes and the mechanism of action of GdA leading to lymphocyte death.

METHODS

Flow cytometry analysis was performed to check for the surface expression of interleukin-2 receptor α (IL-2Rα) and intracellular eomesodermin (Eomes) in activated T-lymphocytes, whereas quantitative RT–PCR analysis was used to find out their mRNA profile upon GdA treatment. Western analysis was carried out to confirm the protein level of Bax and Bcl-2.

RESULTS

GdA reduces the surface expression of the high-affinity IL-2R complex by down-regulating the synthesis of IL-2Rα (CD25). This disturbs the optimal IL-2 signalling and decreases the Eomes expression, which along with IL-2 directly regulates perforin and granzymes expression. Consequently, the CD8⁺ T-lymphocytes undergo growth arrest and are unable to mature into competent cytotoxic T-lymphocytes. In the CD4⁺ T-lymphocytes, growth factor IL-2 deprivation leads to proliferation inhibition, decreased Bcl-2/enhanced Bax expression, culminating in mitochondrial stress and cell death.

CONCLUSIONS

GdA spurs cell cycle arrest, loss of effector functions and apoptosis in different T-cell subsets by making T-lymphocytes unable to respond to IL-2.

Source:
http://humrep.oxfordjournals.org/rss/current.xml

BACKGROUND

Although germ cells in boys with Klinefelter syndrome (KS) are reduced in number as early as infancy, a severe germ cell loss occurs during mid-puberty. Therefore, we wanted to detect spermatogenesis at an early stage and investigate the strategy of preserving spermatozoa and/or testicular spermatogonial stem cells in adolescents with KS when signs of deteriorating spermatogenesis are observed.

METHODS

Tanner staging, testicular size, serum inhibin B and spermaturia were assessed every 4 months before the attempt to procure gametogenic cells in seven non-mosaic 47,XXY adolescents, aged between 10 and 16 years.

RESULTS

Despite an increasing testis volume in the youngest and a Tanner staging of more than three in the oldest patients, no spermaturia was observed. In two patients serum inhibin B increased gradually, while in all others a rather rapid but variable decline was observed at different ages. No spermatozoa were observed after electroejaculation. No spermatocytes or spermatids were found at microscopic examination of single biopsies, while spermatogonia were identified in four subjects, three of whom had measurable serum inhibin B. Massive fibrosis and hyalinization were observed in all biopsies.

CONCLUSION

No spermatogenesis was documented in non-mosaic 47,XXY adolescents either by spermaturia, electroejaculation or testicular biopsy. Neither clinical nor hormonal parameters were of value in determining the timing for optimal spermatogonial stem cell retrieval. More data are needed to elucidate the potential role of testicular tissue cryopreservation in adolescents with KS. Therefore, at present, the cryopreservation of testes tissue for clinical reasons should not be recommended.

Source:
http://humrep.oxfordjournals.org/rss/current.xml

BACKGROUND

Cell-free seminal mRNA (cfs-mRNA) exists in human ejaculate at high concentrations and with high stability, and contains many tissue-specific transcripts secreted from the male reproductive system. Owing to the sensitivity of RNA technology, cfs-mRNAs are ideal candidates for non-invasive biomarkers of physiopathological conditions. This study applied cfs-mRNA in identifying the presence of either germ cells or complete obstruction in men with azoospermia.

METHODS

RT–PCR was performed to amplify the germ cell-specific (DDX4), seminal vesicle-specific (SEMG1) and prostate-specific (TGM4) mRNAs from cfs-mRNAs, which were isolated from the seminal plasma of men with non-obstructive azoospermia (NOA) or obstructive azoospermia (OA). The 39 patients with NOA, diagnosed by testicular biopsy, included 8 men with maturation arrest (MA), 3 men with incomplete sertoli cell only (iSCO) syndrome and 28 men with complete SCO (cSCO). The 29 patients with OA, confirmed by the presence of sperm in the testis or epididymis, included 8 men with congenital bilateral absence of the vas deferens (CBAVD) and 21 men with non-CBAVD. Healthy individuals and vasectomized men were enrolled as controls.

RESULTS

TGM4 was detected in all participants. Consistent with their diagnosis, DDX4 was detected in all patients with MA or iSCO but was absent in most cases of cSCO (n = 21, 75.0%) or non-CBAVD (n = 18, 85.7%), and in all men with vasectomy or CBAVD. The presence of DDX4 in the other seven men with cSCO and three patients with non-CBAVD suggests the presence of germ cells in the testis, and incomplete obstruction, respectively. SEMG1 was undetectable in three patients with CBAVD with bilateral absence of the seminal vesicles, and in two non-CBAVD cases with low ejaculate volume.

CONCLUSIONS

These results suggest that, with high sensitivity and representativity, cfs-mRNA could be non-invasive biomarkers for identifying the presence of germ cells or complete obstruction in azoospermia.

Source:
http://humrep.oxfordjournals.org/rss/current.xml

BACKGROUND

Human toxicity of bisphenol A (BPA), a weak estrogenic environmental endocrine disrupting compound, widely used in plastics, baby bottles, cans and dental sealants, is under investigation. Fetal or perinatal exposure in rodents is associated with programmed adult reproductive diseases. Human epidemiological studies remain scarce, especially concerning testicular development. We have investigated the relationship between fetal exposure to BPA and cryptorchidism.

METHODS

Using a radioimmunoassay performed after extraction, validated by high-performance liquid chromatography and mass spectrometry, active levels of unconjugated BPA (uBPA) in cord blood (CB) were measured in 152 boys born after 34 weeks gestation, with cryptorchid or descended testes.

RESULTS

Active uBPA was detectable in all CB samples, with values in the control group (n = 106) of 0.14–4.76 ng/ml, median: 0.9 ng/ml; mean ± SD: 1.12 ng/ml ± 0.86 ng/ml, which did not differ from cryptorchid boys (n = 46, 1.26 ± 1.13 ng/ml, P = 0.38). uBPA in controls correlated with CB inhibin B (P < 0.01) and total testosterone (P < 0.05), and with maternal milk polychlorinated bisphenyl 138 (P < 0.03). uBPA did not correlate with clinical maternal or fetal parameters or with other steroid or polypeptide CB hormones assessed.

CONCLUSIONS

The presence of uBPA in all CB samples suggests placental transfer and fetal exposure. Similar uBPA levels in the control and cryptorchid groups make the participation of fetal exposure to uBPA in the physiopathology of undescended testes unlikely. However, the observed nanomolar uBPA concentrations support assessment of epidemiological relationships between CB uBPA and other human diseases.

Source:
http://humrep.oxfordjournals.org/rss/current.xml