Search Immortality Topics:

Page 339«..1020..338339340341..350360..»


Category Archives: Human Reproduction

Oocyte activation, phospholipase C zeta and human infertility

BACKGROUND

Mammalian oocytes are activated by intracellular calcium (Ca2+) oscillations following gamete fusion. Recent evidence implicates a sperm-specific phospholipase C zeta, PLC, which is introduced into the oocyte following membrane fusion, as the responsible factor. This review summarizes the current understanding of human oocyte activation failure and describes recent discoveries linking certain cases of male infertility with defects in PLC expression and activity. How these latest findings may influence future diagnosis and treatment options are also discussed.

METHODS

Systematic literature searches were performed using PubMed, ISI-Web of Knowledge and The Cochrane Library. We also scrutinized material from the United Nations and World Health Organization databases (UNWHO) and the Human Fertilization and Embryology Authority (HFEA).

RESULTS AND CONCLUSIONS

Although ICSI results in average fertilization rates of 70%, complete or virtually complete fertilization failure still occurs in 1–5% of ICSI cycles. While oocyte activation failure can, in some cases, be overcome by artificial oocyte activators such as calcium ionophores, a more physiological oocyte activation agent might release Ca2+ within the oocyte in a more efficient and controlled manner. As PLC is now widely considered to be the physiological agent responsible for activating mammalian oocytes, it represents both a novel diagnostic biomarker of oocyte activation capability and a possible mode of treatment for certain types of male infertility.

Posted in Human Reproduction | Comments Off on Oocyte activation, phospholipase C zeta and human infertility

Laboratory and embryological aspects of hCG-primed in vitro maturation cycles for patients with polycystic ovaries

BACKGROUND

In this review, recent advances in the laboratory as well as embryological aspects of hCG priming in vitro maturation (IVM) cycles are described.

METHODS

This report is based on publications from literature searches and the authors' experience.

RESULTS

In IVM cycles, priming with hCG permits the recovery of a certain number of oocytes with an expanding/dispersed cumulus pattern which facilitates its identification within follicular fluid as compared with non-primed IVM cycles. The immature oocytes with dispersed cumulus cells (CC) at collection have high IVM rates and embryo development potentials. Moreover, a few in vivo matured oocytes with dispersed CC can be obtained, and these have produced good quality embryos. hCG can be given to patients when a dominant follicle reaches 10–12 mm to avoid negative effects on the sibling immature oocytes. ICSI should be performed at least 1 h after the first polar body extrusion. Embryo transfer time depends on quantity and quality of the embryos produced after IVM. Compared with slow freezing, vitrification is a more efficient method for freezing the embryos produced from IVM.

CONCLUSIONS

The data from the meta-analyses suggests that the effect on clinical outcome of gonadotrophin priming of IVM still needs to be studied. In order to improve the IVM programs, it is essential to define not only the clinical aspects but also the laboratory and embryological aspects.

Posted in Human Reproduction | Comments Off on Laboratory and embryological aspects of hCG-primed in vitro maturation cycles for patients with polycystic ovaries

Peripheral biomarkers of endometriosis: a systematic review

BACKGROUND

Endometriosis is estimated to affect 1 in 10 women during the reproductive years. There is often delay in making the diagnosis, mainly due to the non-specific nature of the associated symptoms and the need to verify the disease surgically. A biomarker that is simple to measure could help clinicians to diagnose (or at least exclude) endometriosis; it might also allow the effects of treatment to be monitored. If effective, such a marker or panel of markers could prevent unnecessary diagnostic procedures and/or recognize treatment failure at an early stage.

METHODS

We used QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria to perform a systematic review of the literature over the last 25 years to assess critically the clinical value of all proposed biomarkers for endometriosis in serum, plasma and urine.

RESULTS

We identified over 100 putative biomarkers in publications that met the selection criteria. We were unable to identify a single biomarker or panel of biomarkers that have unequivocally been shown to be clinically useful.

CONCLUSIONS

Peripheral biomarkers show promise as diagnostic aids, but further research is necessary before they can be recommended in routine clinical care. Panels of markers may allow increased sensitivity and specificity of any diagnostic test.

Posted in Human Reproduction | Comments Off on Peripheral biomarkers of endometriosis: a systematic review

Size and spatial orientation of uterine tissue transplants on the peritoneum crucially determine the growth and cyst formation of endometriosis-like lesions in mice

BACKGROUND

In many studies in rodents, intraperitoneal endometriosis-like lesions are surgically induced by syngeneic or autologous transplantation of uterine tissue samples, which are sutured to the abdominal wall. However, until now the surgical techniques have not been standardized, and we address this issue here.

METHODS

Uterine tissue samples were transplanted to the peritoneum of C57BL/6 mice (four study groups, n = 7 each). Using non-invasive high-resolution ultrasound imaging over a period of 4 weeks, we analyzed growth characteristics and cyst formation of the endometriosis-like lesions which developed, in relation to mode of transplantation (syngeneic versus autologous), type of tissue fixed adjacent to the peritoneum (endometrium versus perimetrium), and size of tissue transplanted (2 versus 3 mm). Immunohistochemical analysis was also performed.

RESULTS

When the perimetrium, with underlying myometrium, was sutured next to the host peritoneum the endometriosis-like lesions which developed exhibited a higher growth rate (P< 0.05 versus endometrium), and contained more proliferating cell nuclear antigen (PCNA)-positive cells and an increased microvessel density (both P< 0.05 versus endometrium). In the group with 3 mm uterine tissue grafts, lesion growth was significantly decreased when compared with 2 mm samples (P< 0.05). However, the larger grafts developed more cysts throughout the observation period than the smaller ones. There was no difference between syngeneic and autologous endometriosis-like lesions.

CONCLUSIONS

Our study demonstrates that size and spatial orientation of peritoneally fixed uterine tissue samples crucially determine growth and cyst formation of endometriotic lesions in mice. These findings should improve the standardization and reliability of future studies, performed in the frequently used mouse model of surgically induced endometriosis.

Posted in Human Reproduction | Comments Off on Size and spatial orientation of uterine tissue transplants on the peritoneum crucially determine the growth and cyst formation of endometriosis-like lesions in mice

Decreased pregnancy rate is linked to abnormal uterine peristalsis caused by intramural fibroids

BACKGROUND

The relationship between fibroids and infertility remains an unsolved question, and management of intramural fibroids is controversial. During the implantation phase, uterine peristalsis is dramatically reduced, which is thought to facilitate embryo implantation. Our aims were to evaluate (i) the occurrence and frequency of uterine peristalsis in infertile women with intramural fibroids and (ii) whether the presence of uterine peristalsis decreases the pregnancy rate.

METHODS

Ninety-five infertile patients with uterine fibroids were examined using magnetic resonance imaging (MRI). Inclusion criteria were as follows: (i) presence of intramural fibroids, excluding submucosal type; (ii) no other significant infertility factors (excluding endometriosis); and (iii) regular menstrual cycles, and MRI performed at the time of implantation (luteal phase day 5–9). The frequency of junctional zone movement was evaluated using cine-mode-display MRI. After MRI, patients underwent infertility treatment for up to 4 months, and the pregnancy rate was evaluated prospectively.

RESULTS

Fifty-one patients fulfilled the inclusion criteria, and 29 (57%) and 22 (43%) patients were assigned to the low (0 or 1 time/3 min) or high frequency (≥2 times/3 min) uterine peristalsis group, respectively. Endometriosis incidence was the same in both groups. Ten out of the 29 patients (34%) in the low-frequency group achieved pregnancy, compared with none of the 22 patients (0%) in the high-frequency group (P< 0.005). Comparing pregnant and non-pregnant cases, 4 of 10 patients (40%) and 9 of 41 patients (22%), respectively, had endometriosis (not significant).

CONCLUSIONS

A higher frequency of uterine peristalsis during the mid-luteal phase might be one of the causes of infertility associated with intramural-type fibroids.

Posted in Human Reproduction | Comments Off on Decreased pregnancy rate is linked to abnormal uterine peristalsis caused by intramural fibroids

In situ identification of follicles in ovarian cortex as a tool for quantifying follicle density, viability and developmental potential in strategies to preserve female fertility

BACKGROUND

Ovarian tissue cryopreservation, in combination with autotransplantation or long-term culture, has been proposed as a means of fertility preservation. However follicle density within ovarian cortex has a profound impact on the success of in vivo and in vitro systems designed to support follicle growth and restore fertility. The objective of this study was to investigate the dye neutral red (NR) as a tool to quantify follicle density in situ, without compromising follicle viability and developmental potential.

METHODS

In the first experimental series thin slices of cryopreserved and fresh ovine cortical tissue were incubated in 50 µg/ml NR and assessed for the presence of red colouration. Slices were then used for follicular structure isolation and viability evaluation using 5-(and 6)-carboxyfluoresceindiacetate succinimidylester (CFDA-SE), or prepared histologically for follicle counting or evaluation of apoptosis via terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL). An additional subset of slices were cultured for 8 days, followed by re-evaluation of follicle viability. NR staining was further assessed in a pilot study using thin slices of cryopreserved human ovarian tissue donated by 17 patients undergoing laparoscopic sterilisation or elective Caesarean section.

RESULTS

In both ovine and human ovarian cortex NR concentrated in follicular structures within weakly stained stroma. NR colouration was observed in 41.7 ± 4.6% of cryopreserved and 49.3 ± 6.5% of the fresh ovine tissue slices, and NR staining was consistently predictive of the presence of follicles. Non-stained ovine slices contained highly apoptotic follicles, while lower levels of apoptosis were observed in NR positive slices, indicating preferential detection of viable follicles by NR. Following culture the majority of ovine slices re-stained with NR, no significant increases in the levels of apoptosis were observed and 94.6 ± 3.1% of follicles were viable by CFDA-SE. In the human study, NR identified follicles in 19.3 ± 3.7% of tissue slices, and follicle density tended to decrease with advancing patient age.

CONCLUSIONS

NR predicts viable follicle density in situ in slices of ovine and human ovarian cortex. Furthermore incubation of tissue in NR prior to culture does not compromise subsequent follicle survival in vitro, indicating the potential suitability of this approach in fertility preservation regimes.

Posted in Human Reproduction | Comments Off on In situ identification of follicles in ovarian cortex as a tool for quantifying follicle density, viability and developmental potential in strategies to preserve female fertility