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J Tesarik

Publications and source records attributed to J Tesarik.

At least 37 records · Page 2Linked to original sources
PubMed1999

Relationship between fertilization results after intracytoplasmic sperm injection, and intrafollicular steroid, pituitary hormone and cytokine concentrations.

Previous studies relating hormone and cytokine concentrations in follicular fluid to oocyte fertilizability were flawed by the uncertainty about the actual oocyte maturity status at the time of recovery and by the possible contribution of the male factor to failures of conventional in-vitro fertilization. This is the first study in which oocyte maturity was assessed immediately after recovery and only mature oocytes were selected for treatment by intracytoplasmic sperm injection. Fertilization outcomes were related to follicular fluid concentrations of 17beta-oestradiol, progesterone, follicle stimulating hormone, luteinizing hormone (LH), growth hormone (GH), prolactin (PRL), interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF alpha). Those oocytes that subsequently showed normal fertilization were harvested from follicles with higher concentrations of progesterone, GH, PRL, IL-1 and TNF alpha as compared with those of oocytes that failed to fertilize. Among the normally fertilized oocytes, low GH concentrations were associated with the failure of cleavage and with poor morphology of cleaving embryos, whereas rapidly cleaving embryos developed from oocytes recovered from follicles with high concentrations of LH and IL-1. These data suggest important roles for GH, IL-1 and TNF alpha, and of residual LH after pituitary suppression, as positive regulators of the final phase of oocyte intrafollicular development.

Cytokines↗
PubMed1999

Clinical efficacy of spermatid conception: analysis using a new spermatid classification scheme.

Fertilization and pregnancy outcomes of 50 round spermatid injection (ROSI) and 20 elongated spermatid injection (ELSI) treatment cycles are related to various characteristics of the cycles, with particular reference to spermatid developmental stage as assessed by using a classification scheme adapted to this purpose. Although this classification includes eight stages, a complete block was mostly detected at the earliest stage (Sa1) or at the latest stages (Sd1 and Sd2). Thus, spermiogenesis was blocked at Sa1 stage in 50 cases (71%), at Sd1 stage in eight cases (11%) and at Sd2 stage in 10 cases (14%). Only in two cases (3%) was spermiogenesis blocked at an intermediate stage (Sb2). Globally, fertilization rates were higher for ELSI than for ROSI. No pregnancy was achieved in the ROSI cycles, whereas nine pregnancies resulted from the ELSI cycles. Two of them (both with Sd2 spermatids) ended in a first trimester spontaneous abortion. Of the seven ongoing pregnancies, five are singleton (two with Sd1 spermatids, two with Sd2 spermatids, and one after a mixed transfer after injection of Sa2 and Sd1 spermatids) and two are twin (one with Sd1 and the other with Sd2 spermatids). No pregnancy was achieved in the two cycles with Sb2 spermatids. One of the two twin pregnancies has already resulted in the birth of two healthy children.

Adult↗
PubMed1999

The probability of abnormal preimplantation development can be predicted by a single static observation on pronuclear stage morphology.

This retrospective study was undertaken to determine whether further developmental progression of two-pronucleated (2PN) zygotes can be predicted by a single, non-invasive examination of pronuclei, with the use of criteria based on the number and distribution of nucleolar precursor bodies in each pronucleus. The normal range of pronuclear variability was defined by analysis of zygotes giving rise to embryos transferred in 100%-implantation cycles (pattern 0). Morphological patterns differing from pattern 0 were classified as patterns 1-5. The frequency of developmental arrest of pattern 0 zygotes was only 8.5% as compared with 31.6, 21.9, 30.0, 20.5 and 24. 1% for patterns 1-5 respectively. Relationships of pronuclear patterns with blastomere multinucleation and cleaving embryo morphology were also noted. Clinical pregnancy was achieved in 22 of 44 (50%) treatment cycles in which at least one pattern 0 embryo was transferred, but only in two of 23 (9%) cycles in which only pattern 1-5 embryos were transferred. These data present new evaluation criteria which can be used to predict the developmental fate of human embryos as early as the pronuclear stage, without requiring repeated observations or an exact timing of pronuclear zygote inspection. Further prospective study is needed for clinical validation of these criteria.

Blastocyst↗
PubMed1999

Assisted reproduction for testicular failure: management of germ cell maturation arrest.

The availability of current, state of the art technology has enabled an efficient treatment in cases of infertility caused by testicular failure in which mature spermatozoa or late elongated spermatids can be recovered from the ejaculate or the testis. In those patients in whom only germ cells at earlier stages of spermatogenesis are present, results of the currently available treatments are still inconsistent and largely unpredictable, although some encouraging developments have been achieved over the past year. These new results suggest that developmental failure after fertilization with immature germ cells is mainly due to germ cell apoptosis and shows that an efficient selection of healthy germ cells can be achieved by in-vitro culture. In some cases, this method also allows premeiotic germ cells to achieve in-vitro transmeiotic maturation and thus enables men with in-vivo premeiotic maturation arrest to father a child.

Apoptosis↗
PubMed1998

Treatment of severe male infertility by micromanipulation-assisted fertilization: news and views.

Recent progress in cell micromanipulation has made it possible to achieve fertilization even with highly deficient male gametes, by injecting them directly to oocyte cytoplasm. This technique, known as intracytoplasmic sperm injection (ICSI), has proved efficient in most types of sperm pathology. However, ICSI fails when injected spermatozoa are not capable of supporting the process of oocyte activation or when they carry genetic abnormalities incompatible with normal embryonic development. Abnormalities of oocyte activation and the transmission of genetic anomalies to the progeny are also two major concerns relating to the clinical use of ICSI. The use of micromanipulation-assisted fertilization in cases of male germ cell maturation arrest, namely fertilization by round spermatid injection (ROSI), has brought preliminary clinical results, and the improvement of ROSI clinical efficacy remains a major challenge for future research.

Acrosome Reaction↗
PubMed1998

Pregnancy and birth after transfer of embryos that developed from single-nucleated zygotes obtained by injection of round spermatids into oocytes.

OBJECTIVE: To use injection of spermatids into oocytes as a mode of infertility treatment in cases in which spermatozoa are not available. DESIGN: Prospective clinical evaluation and case report. SETTING: In Vitro Fertilization Unit, Herzliya Medical Centers, Herzliya-on-Sea, Israel. PATIENT(S): Thirteen couples with male factor infertility in which the male partner lacked spermatozoa in the ejaculate or testicular biopsy samples. INTERVENTION(S): Round spermatid injection and elongated spermatid injection into oocytes. MAIN OUTCOME MEASURE(S): Evaluation of the rate of two-pronucleated and single-nucleated zygote development. RESULT(S): The rate of two-pronucleated zygote development after round spermatid injection and elongated spermatid injection was relatively low (27% and 36%, respectively). Single-nucleated zygotes develop more frequently after round spermatid injection and elongated spermatid injection (35% and 17%, respectively) than after intracytoplasmic sperm injection with mature spermatozoa. A normal pregnancy and childbirth resulted from the transfer of 4 cleaving embryos, each of which developed from a single-nucleated zygote in a round spermatid injection treatment cycle with ejaculated spermatids. CONCLUSION(S): Embryos derived from single-nucleated zygotes after spermatid conception can be viable and give rise to an ongoing clinical pregnancy and childbirth.

Adult↗
PubMed1998

Differentiation of spermatogenic cells during in-vitro culture of testicular biopsy samples from patients with obstructive azoospermia: effect of recombinant follicle stimulating hormone.

In-vitro differentiation of spermatogenic cells is a potential approach to the treatment of male sterility due to spermatogenic arrest. This is a pilot study evaluating meiotic, morphogenetic and cytoplasmic maturation of spermatogenic cells from 18 patients with obstructive azoospermia, during in-vitro culture of partly disintegrated testicular biopsy samples in the presence or absence of recombinant follicle stimulating hormone (rFSH). Meiotic progression was detectable only in the presence of rFSH in culture medium. FSH-dependent condensation, peripheral migration and protrusion of spermatid nuclei, together with FSH-independent flagellar growth, were the main events indicating post-meiotic sperm cell differentiation. rFSH also promoted the progression of spermatid cytoplasmic maturation, reflected by acceleration of acrosomal development. These differentiation events appeared to be mediated by humoral activity of Sertoli cells, without the need for a direct Sertoli-sperm cell contact. These findings provide a background for similar studies in patients with non-obstructive azoospermia. If reproducible in the latter group, transmeiotic in-vitro differentiation of primary spermatocytes may be useful in cases of complete maturation arrest, whereas the development of culture-specific forms may help select viable spermatids in cases of complete spermiogenesis failure.

Acrosome↗
PubMed1998

Oocyte activation after intracytoplasmic injection of mature and immature sperm cells.

The inactivation of metaphase-promoting factor (MPF), leading to reactivation of the oocyte cell cycle after fertilization, is one of the most important results of oocyte activation in the case of intracytoplasmic injection of mature or immature sperm cells. Oocyte activation is a cell signalling event that is likely to imply receptors at the oocyte plasma membrane and a signal transduction pathway involving calcium and protein phosphorylation/dephosphorylation. The typical calcium signal during oocyte activation in mammals takes the form of calcium oscillations. Intracytoplasmic sperm injection (ICSI) is associated with a slightly different pattern of calcium oscillations in comparison with normal fertilization. Available data suggest that sperm cytosolic factor(s) play a role of oscillator, modulating the properties of the oocyte's intracellular calcium stores, whereas the role of trigger, normally realized by spermoocyte interactions at the level of their respective cell surfaces, can be supplemented in the conditions of ICSI by an artificial calcium influx generated by the procedure itself. Delayed onset and an abnormal form of the oocyte activation-promoting calcium signal are the two known molecular abnormalities of human oocyte activation; they can lead to fertilization failure and are also suspected to be at the origin of various embryo abnormalities. The impact of oocyte activation abnormalities on future development increases when oocytes are fertilized with immature sperm cells (spermatids) because the chromatin of these cells is less protected than sperm chromatin against a rapid action of the oocyte's MPF. If oocyte stimulation by the sperm calcium oscillation-promoting activity, which first appears at the round spermatid stage of human spermatogenesis, is insufficient to cause a rapid inactivation of MPF, premature condensation of spermatid chromatids may lead to aneuploidy.

Cellular Senescence↗
PubMed1998

Spermatids as gametes: indications and limitations.

The feasibility of achieving viable embryos, developing to term after transfer into the uterus, by fertilizing oocytes with spermatids has been demonstrated both in animal studies and in preliminary human clinical trials. Here we review the current clinical indications of spermatid conception and discuss the predictable success rates associated with each of these indications. Potential health hazards relating to the use of spermatids for conception are updated taking into account the risk of abnormal or incomplete epigenetic modifications of newly discovered human imprinted genes. We also add new experimental data showing the occurrence of spermatids in patients lacking spermatozoa and demonstrating that round spermatids recovered from patients with complete spermiogenesis failure (no elongated spermatids or spermatozoa ever detected in the patient's history) are often deficient in the factor(s) responsible for oocyte activation. The possible consequences of this deficiency for the occurrence of abnormal fertilization patterns and for the impairment of further preimplantation and post-implantation development are discussed. It is concluded that the development of diagnostic tests to assess the intrinsic quality of spermatids, with regard to their ability to act as gametes, is urgently needed as part of pre-treatment diagnosis before infertile couples are included in a spermatid conception programme. Centres wishing to use spermatids in human assisted reproduction should also be prepared to offer adequate diagnostic methods to control genomic imprinting abnormalities in the progeny.

Female↗
PubMed1998

Germ cell apoptosis in men with complete and incomplete spermiogenesis failure.

Germ cell apoptosis was evaluated in 11 men suffering from nonobstructive azoospermia and enrolled in a spermatid conception programme. In six of these patients, round spermatids (Sa stage) were the most advanced spermatogenic cells recovered from testicular biopsy samples. This condition is referred to as complete spermiogenesis failure. In the remaining five men, a few late elongated spermatids (Sd stage) were unexpectedly found in the testicular biopsy samples on the day of treatment. This condition is referred to as incomplete spermiogenesis failure. Germ cell apoptosis in both groups of patients was examined by analysing cell smears prepared from mechanically disintegrated testicular tissues using terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL), which detects apoptosis-specific DNA fragmentation, and annexin-V binding, detecting apoptosis-related translocation of plasma membrane phosphatidylserine to the membrane's outer surface. Both methods were combined, in double-fluorescence labelling preparations, with immunocytochemical detection of proacrosin, a specific germline marker. Patients with complete spermiogenesis failure had significantly higher frequencies of primary spermatocytes and round spermatids carrying the apoptosis-specific DNA damage in comparison with patients with incomplete spermiogenesis failure. Surprisingly, apoptosis-related phosphatidylserine externalization occurs rarely until the advanced stages of spermiogenesis. Since externalized phosphatidylserine is expected to be involved in the recognition of apoptotic cells by phagocytes, apoptotic spermatocytes and round spermatids may not be removed easily by phagocytosis. The high frequency of DNA damage in round spermatids from patients with complete spermiogenesis failure explains the low success rates of spermatid conception in these cases. The evaluation of apoptosis can help predict success rates of spermatid conception.

Annexin A5↗
PubMed1998

Nongenomic effects of androstenedione on human granulosa luteinizing cells.

This study examines rapid (5-60 s) effects of androgens on the cytosolic free Ca2+ concentration ([Ca2+]i) in human granulosa lutenizing cells. Cells were obtained from human preovulatory follicles, and [Ca2+]i was measured with the use of the Ca(2+)-responsive fluorescent dye fluo-3. Molar concentrations between 100 pmol/L and 1 mumol/L androstenedione increased [Ca2+]i within 5 s after addition to cells. This [Ca2+]i increase resulted from both Ca2+ influx, as shown by the effects of ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and the voltage-dependent Ca2+ channel blocker verapamil, and Ca2+ mobilization from the endoplasmic reticulum, as shown by the effects of thapsigargin. Treatment with pertussis toxin and U-73,122, a specific inhibitor of phospholipase C, abolished the effects of androstenedione on [Ca2+]i. Flutamide, a nuclear androgen receptor antagonist, did not block the increase in [Ca2+]i induced by androstenedione. Testosterone (100 pmol/L to 1 mumol/L) had no effect. This is the first report showing that androstenedione increases [Ca2+]i in granulosa cells. These data provide evidence for the presence in granulosa cells of a novel, short term mechanism of androstenedione action involving voltage-dependent Ca2+ channels in the plasma membrane and phospholipase C activation via a pertussis toxin-sensitive G protein.

Actins↗
PubMed1998

Human spermatogenesis in vitro: respective effects of follicle-stimulating hormone and testosterone on meiosis, spermiogenesis, and Sertoli cell apoptosis.

In spite of the availability of abundant data about in vitro spermatogenesis in laboratory animals, studies on human in vitro spermatogenesis are scarce. This study employed a relatively simple culture system, involving all cell types of seminiferous tubules, to analyze the effects of FSH and testosterone (T) on different characteristics of human germ and Sertoli cells in culture. By using fluorescence in-situ hybridization, we show that in vitro reduction of germ cell ploidy can be stimulated by FSH but not by T. FSH, but not T, also induced unexpectedly rapid (24-48 h) morphological changes resembling spermiogenesis, although individual changes (spermatid nucleus condensation and protrusion, cell body elongation, and flagellar growth) proceeded in an uncoordinated way and mostly resulted in the development of abnormal forms of elongated spermatids. Though ineffective alone, T potentiated the effects of FSH on meiosis and spermiogenesis. These effects of T were probably caused by the prevention of Sertoli cell apoptosis, an effect that could not be mimicked by FSH. These data show that, in the presence of high concentrations of FSH and T, human spermatogenesis can proceed in vitro with an unusual speed, but the resulting gametes are morphologically abnormal. The potential practical relevance of these findings to assisted reproduction remains to be assessed.

Adult↗