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Biomedical subjects

L Yogev

Publications and source records attributed to L Yogev.

At least 19 recordsLinked to original sources
PubMed2006

Expression profile of AZF genes in testicular biopsies of azoospermic men.

BACKGROUND: The Y-chromosome AZF regions include genes whose functions and specific roles in spermatogenesis have not been fully clarified. This study investigated the expression of several AZF (USP9Y, DDX3Y/DDX3Yt1, EIF1AY and PRY) and USP9X transcripts in testicular biopsies of 89 azoospermic men who had been classified by histology and cytology assessments. METHODS: Expression was analysed by RT-PCR, and some biopsies were evaluated by multiplex RT-PCR. Quantitative PCR was performed in some biopsies to determine the ratio of the testis-specific transcript DDX3Yt1 to the total DDX3Y transcription. RESULTS: The expression of USP9Y, USP9X and DDX3Y was found in all the specimens tested, whereas DDX3Yt1 expression was diminished or undetectable in several biopsies with impaired spermatogenesis. EIF1AY was detected in all except two of the specimens. Noteworthy, PRY expression was detected mainly in biopsies with germ cells, and this association was significant (P < 0.001). An identical expression profile was obtained by either single or multiplex RT-PCR. CONCLUSIONS: These findings suggest that PRY is usually expressed in germ cells, whereas the other transcripts are also expressed in testicular somatic cells. The absence of EIF1AY expression might sporadically contribute to azoospermia. The decreased ratio of DDX3Yt1/DDX3Y transcript in impaired spermatogenesis suggests that the DDX3Yt1 transcript is under-expressed in impaired spermatogenesis. The findings contribute to the search and selection of the most valuable gene markers potentially useful as additional tools for predicting complete spermatogenesis by multiplex expression analysis.

Azoospermia↗
PubMed2004

Seasonal variations in pre- and post-thaw donor sperm quality.

BACKGROUND: The present study was conducted to evaluate seasonal variability in the quality of pre- and post-thaw semen parameters among sperm bank donors. METHODS: The first two consecutive ejaculates during the months March (spring, 92 males), June (summer, 97 males), September (autumn, 81 males) and December (winter, 97 males) were analysed. A comparison was made between sperm parameters from the same sperm donor at different seasons. Only males who donated semen samples during at least two seasons were enrolled in the study group (n = 103). Sperm specimens were cryopreserved in aliquots with fixed range of 8-12 x 10(6)/ml of progressive motile sperm concentration after thawing. RESULTS: Differences between months were found in sperm concentration (P = 0.030) and normal morphology (P = 0.038); highest values were found in March and December, and the lowest in September. Mean specimen volume and percent of motile sperm cells did not vary throughout the seasons. The freezability of the donors' sperm dropped dramatically from March to September, as determined by the number of straws (fixed aliquots of 0.5 ml) and total thawed progressive motile sperm that were cryopreserved for each male (P = 0.017 and P = 0.002, respectively). CONCLUSIONS: Cryopreservation of donor sperm is more effective during winter and spring than during the rest of the year.

Adult↗
PubMed2001

Modified testicular expression of stress-associated "readthrough" acetylcholinesterase predicts male infertility.

Male infertility is often attributed to stress. However, the protein or proteins that mediate stress-related infertility are not yet known. Overexpression of the "readthrough" variant of acetylcholinesterase (AChE-R) is involved in the cellular stress response in a variety of mammalian tissues. Here, we report testicular overexpression of AChE-R in heads, but not tails, of postmeiotic spermatozoa from mice subjected to a transient psychological stress compared with age-matched control mice. Transgenic mice overexpressing AChE-R displayed reduced sperm counts, decreased seminal gland weight, and impaired sperm motility compared with age-matched nontransgenic controls. AChE-R was prominent in meiotic phase spermatocytes and in tails, but not heads, of testicular spermatozoa from AChE-R transgenic mice. Head-localized AChE-R was characteristic of human sperm from fertile donors. In contrast, sperm head AChE-R staining was conspicuously reduced in samples from human couples for whom the cause of infertility could not be determined, similar to the pattern found in transgenic mice. These findings indicate AChE-R involvement in impaired sperm quality, which suggests that it is a molecular marker for stress-related infertility.

Acetylcholinesterase↗
PubMed2001

Expression of CDY1 may identify complete spermatogenesis.

OBJECTIVE: To investigate the expression of deleted in azoospermia (DAZ), RNA-binding motif (RBM), and chromodomain y1 (CDY1) genes in the testes of men with azoospermia with variable histopathologies. DESIGN: Prospective study. SETTING: Andrology laboratory of a university-affiliated maternity hospital. PATIENT(S): Sixty-six men with azoospermia. INTERVENTION(S): Testicular sperm extraction. MAIN OUTCOME MEASURE(S): The results of gene expression in testicular tissue tested by RT-PCR were correlated with those of histopathologically and microscopically examined minced testicular tissue. Y chromosome microdeletion testing and karyotyping were performed, as was direct sequencing of CDY1-PCR products. RESULT(S): CDY1-minor expression was detected in all biopsies in which mature spermatids/spermatozoa were observed by histological analysis and/or in the minced tissue. CDY1-minor expression was also detected in two biopsies with arrest at the spermatocyte stage during which no mature spermatids/spermatozoa were observed. A previously unreported CDY1-minor alternative splicing transcript was identified. DAZ and RBM gene expressions were detected in all biopsies in which at least a few germinal cells in early stages were found and in one biopsy histologically determined as Sertoli cell only. CONCLUSION(S): Our preliminary results suggest that CDY1-minor expression might increase the prospect for complete spermatogenesis, while RBM and DAZ expression can only be indicative of the presence of germinal cells.

Adult↗
PubMed2001

Vascularity index distribution within the testis: a technique for guiding testicular sperm extraction.

Azoospermia is defined as the absence of spermatozoa in the ejaculate, although some foci of spermatogenesis may exist in the testes of these men. Currently, there are no clinical, seminal or hormonal parameters for identifying spermatogenesis within the testis sufficient for achieving genetic offspring. As a result, multiple biopsies are performed at several arbitrary sites of both testes in search of spermatozoa. We developed a power Doppler (PD) ultrasound (US) image-based technique that predicts sites with the greatest potential for spermatogenesis. PDUS images of the testes of azoospermic men were acquired at seven cross-sections to reconstruct a 3-D matrix for constructing a spatial map of preferential regions where spermatozoa are most likely to exist. This technique may obviate the need for arbitrary multiple biopsies that inflict some degree of damage upon testicular tissue, and may increase the success rate of identifying viable spermatozoa in testicular biopsies.

Biopsy↗
PubMed2001

Intrauterine insemination in male factor subfertility: significance of sperm motility and morphology assessed by strict criteria.

The study was conducted to evaluate the results of IUI treatment in a homogenous group with male factor infertility, and to assess the correlation of sperm variables, including sperm morphology by strict criteria, with pregnancy achievement after IUI. A total of 108 couples with no apparent female aetiology for infertility underwent 264 intrauterine insemination treatment cycles. A comparison was made between the sperm variables in two groups in which the achievement of pregnancy differed. The percentage of motile spermatozoa, degree of motility and normal morphology (by strict criteria) were significantly higher in the pregnant group compared with that of the nonpregnant group. A significant difference in pregnancy rates per couple after intrauterine insemination was demonstrated among three groups according to the percentage of sperm morphology, i.e. poor (< 4%), fair (4-14%) or good (> 14%) (11.1%; 36.1% and 50.0%, respectively). Intrauterine insemination is a valid mode of treatment in cases with male infertility, provided that normal morphology by strict criteria is higher than 4%.

Adult↗
PubMed2001

Effect of freezing-thawing on the expression of mannose-ligand receptors on human spermatozoa: the impact on sperm capacitation and acrosome reaction.

The aim of this study was to evaluate the change in the expression of mannose-ligand receptors following a freezing-thawing procedure, in order to assess its impact on sperm capacitation and acrosome reaction. Twenty semen samples were obtained from fertile donors. Sperm samples were divided into two equal volumes. One aliquot was cryopreserved and the other aliquot was incubated at 32 degrees C. After 2 h the frozen sample was thawed and both samples were further incubated at 32 degrees C to allow capacitation. Mannose receptors were examined following 4 and 22 h of incubation using a mannosylated-BSA-FITC probe. The expression of mannose-ligand receptors on the sperm plasma membrane was determined according to the fluorescence pattern: pattern I represents pre-capacitation, pattern II represents capacitated spermatozoa and pattern III represents acrosome-reacted spermatozoa. After 4 h incubation in capacitating medium, the percentages of patterns I, II and III were 90, 7 and 3% for fresh spermatozoa and 89, 8 and 3% for frozen-thawed spermatozoa, respectively (P > 0.05). Following 22 h of incubation, the percentages of patterns I, II and III were 84, 11 and 5 for fresh spermatozoa and 83, 11 and 6% for frozen-thawed spermatozoa, respectively (not significant at P > 0.05). The percentages of patterns II and III in fresh and frozen-thawed spermatozoa were increased by the same magnitude with longer incubation in the capacitating conditions. It was concluded that the freezing-thawing procedure for human spermatozoa does not affect the expression of mannose-ligand receptors and the dynamics of sperm pre-fertilization processes.

Acrosome Reaction↗
PubMed2001

High levels of catecholamines in human semen: a preliminary study.

The objective of this study was to determine the seminal concentrations of four different catecholamines and their association with semen quality. Seminal concentrations of adrenaline, noradrenaline, 3,4-dihydroxy-phenylalanine (DOPA), and 3,4-dihydroxy-phenyl acetic acid (DOPAC) were determined in 13 healthy volunteers, using high-performance liquid chromatography with an electrochemical detector. In addition, semen analysis was performed. Noradrenaline and DOPA were present in all specimens with a concentration of 15 181+/- 2951 pg ml(-1) and 4023 +/- 429 pg ml(-1) (mean +/- SE), respectively. These concentrations are respectively 19 times (range: 3-44) and twice (range: 1-3) as high as the maximal normal concentration in plasma. Adrenaline was present in 10 and DOPAC in seven of 13 specimens. No correlation was found between the concentration of any of the catecholamines evaluated and semen characteristics. In conclusion, noradrenaline and DOPA are present in human semen at concentrations that are much higher than maximal normal values in plasma. Adrenaline and DOPAC were also found in some of the samples. The concentrations of catecholamines in semen are not associated with semen quality.

Adult↗
PubMed2001

The contribution of RNA-binding motif (RBM) antibody to the histopathologic evaluation of testicular biopsies from infertile men.

Testicular biopsies of infertile men are often characterized by mixed histologic patterns, with different types of spermatogenic impairments being found in adjacent seminiferous tubules. RNA-binding motif (RBM) is a nuclear protein expressed exclusively in the male germ cell line. We reasoned that RBM might be a useful marker to identify germ cells in testicular sections, particularly in biopsies with mixed histologic phenotype and small focal concentrations of spermatogenesis. Testicular biopsies from azoospermic men were immunohistochemically evaluated for RBM expression. RBM expression was detectable in spermatogonia, spermatocytes, and round spermatids in biopsies of men with obstructive azoospermia and normal spermatogenesis. No specific cell staining was shown in cases of Sertoli-cell-only (SCO) syndrome. In biopsies of patients with spermatogenic disorders, all the germ cells were stained up to and including the stage level of the arrest in spermatogenesis. This approach enabled identification of small focal concentrations of spermatogenesis in a biopsy previously classified as being SCO by hematoxylin and eosin staining. Thus, RBM can be a useful immunohistochemical marker for the specific identification of germ cells and provide greater accuracy in the histopathologic evaluation of testicular biopsies.

Antibodies↗
PubMed2001

Results of 6139 artificial insemination cycles with donor spermatozoa.

BACKGROUND: Artificial insemination by donor spermatozoa (AID) can prove a valuable treatment for a number of male factor disorders, although its success rate is variable. METHODS: Retrospective analysis of the results of 6139 cycles performed in 1001 women during an 18 year period is presented. Pregnancy rates per cycle are presented as a function of: female fertility history, treatment modalities, medication used for induction of ovulation, female age, year of treatment, consecutive cycle effect and the use of fresh versus frozen-thawed spermatozoa. RESULTS: Overall pregnancy rate of 12.6% and cumulative pregnancy rate after 12 months of treatment of 75% were achieved. Age was found to be the most important determinant for success rate. CONCLUSIONS: Since the establishment of AID treatments, the mean age of the population of women receiving treatment has increased each year. Consequently, success rate did not improve, even with the use of more sophisticated medical modalities.

Abortion, Spontaneous↗
PubMed2001

The prognostic role of the extent of Y microdeletion on spermatogenesis and maturity of Sertoli cells.

Substantial involvement of the Y chromosome in sexual development and spermatogenesis has been demonstrated. Over the last decade, varying extent of Y chromosome microdeletions have been identified among infertile patients with azoospermia or oligozoospermia. These microdeletions were clustered in three main regions named AZFa, AZFb, and AZFc. Analysis of the Y chromosome microdeletion was found to be of prognostic value in cases of infertility, both in terms of clinical management as well as for understanding the aetiology of the spermatogenesis impairment. However, the accumulated data are difficult to analyse, due to the variable extent of these deletions, the different sequence-tagged sites (STS) used to detect the microdeletions, and the non-uniformity of the histological terminology used by different investigators. This debate discusses the chances of finding testicular spermatozoa in men with a varying extent of Y chromosome microdeletions. The genotype and germ cell findings in men with AZFa microdeletions as well as those that include more than a single AZF region are reviewed, as is the effect of Y chromosome AZF microdeletions on the maturity of the Sertoli cells.

Cellular Senescence↗
PubMed2000

Effect of photoperiod variation on testes and accessory sex organs in the male blind mole rat Spalax ehrenbergi.

The blind mole rat is a seasonally breeding fossorial rodent that is perceptionally blind. This study examines the effect of photoperiod on the morphology and histology of the male mole rat reproductive system, three groups of male mole rats were maintained in the laboratory under short day (SD) conditions (9L: 15D); long day (LD) conditions (15L:9D); and constant darkness (CD), and compared to animals trapped in the field (FL). It was found that the field animals revealed higher testes and prostate gland weights, higher prostate tubuli volume (v*) and lower testes tubuli volume (v*) compared to the other three groups. Distribution of the tubuli in the testes (Vv) was low in the FL group compared to the SD and LD groups but still higher than in the CD group. Distribution of lumen in the testes (Vv) was higher in the CD group in comparison to the other three groups. Distribution of interstitial tissue in the testes (Vv) was higher in the FL group than in the other three groups. Electrolytes and elements secreted from the prostate gland did not differ among the four groups. In the FL group distribution of the tubuli (Vv) in the prostate gland was low and lumen ratio (Vv) was high compared to the other three groups. Distribution of connective tissue in the prostate gland did not differ among all four groups. Testosterone levels and total sperm count was highest in the FL group. Sperm production was noted in all groups; however spermatid and spermatozoa cell production was higher in the FL group. This study shows that photoperiod could be important in initiating timing in the breeding season but that certain other conditions which are absent in the laboratory appear to be responsible for successful breeding in the field.

Animals↗
PubMed2000

Zona pellucida binding improvement effect of different sperm preparation techniques is not related to changes in sperm motility characterizations.

OBJECTIVE: To study the relation between changes in sperm motion characteristics and sperm binding capacity to the zona pellucida (ZP) after different sperm preparation techniques. DESIGN: Prospective study. SETTING: Andrology laboratory at the Lis Maternity Hospital. PATIENT(S): Sixty-three infertile men. INTERVENTION(S): In vitro preparation of 57 sperm samples by pentoxifylline (PTX), 38 samples by SpermPrep I (SP1), and 27 samples by mini-Percoll (mPER). Sperm preparation was evaluated in comparison with the control washing technique. MAIN OUTCOME MEASURE(S): Motility variables and binding capacity. RESULT(S): Binding capacity after PTX, SP1, and mPER preparation methods was significantly higher compared with the control medium preparation. Computer-assisted sperm analysis (CASA) of sperm motility revealed a significant increase in a number of variables after the different treatments. A statistically significant but low correlation was observed between sperm binding capacity after control swim-up preparation and VAP (r = 0.27) as well as with VSL (r = 0.30). No significant correlations were found between the changes in the CASA and the improved sperm binding to the ZP. CONCLUSION(S): The two biologic effects of binding capacity enhancement and motility features improvement are not related. Furthermore, because the binding assay is highly correlated with fertilization capacity, these alterations in motility, as evidenced by CASA, probably have a minor effect on fertilization in vitro.

Electronic Data Processing↗
PubMed2000

Evaluation of meiotic impairment of azoospermic men by fluorescence in situ hybridization.

OBJECTIVE: To identify predictive criteria for the existence of spermatogenesis in nonobstructive azoospermic men. DESIGN: Prospective study. SETTING: Andrology laboratory at a teaching hospital. PATIENT(S): Twenty-two azoospermic men were divided into three groups by qualitative testicular histopathology and the presence of spermatozoa in minced biopsies. INTERVENTION(S): Testicular biopsies evaluation. MAIN OUTCOME MEASURE(S): The presence of spermatozoa and/or mature spermatids, the percentage of sex vesicle formation (X and Y chromosomes in proximity), and the pairing of the two 18 homologous chromosomes. RESULT(S): Spermatozoa and mature spermatids were found in 17 study patients. Whenever few mature spermatids and/or spermatozoa were found, the rates of X-Y and 18 bivalents were significantly higher (mean +/- SD, 73% +/- 13. 3% and 91% +/- 7.1%) than those in cases of spermatocyte maturation arrest (23% +/- 8.0% and 60% +/- 11.8%, respectively). CONCLUSION(S): Pairing of chromosomes during meiosis is apparently related to the progression of spermatogenesis. Consequently, high rates of bivalent formation increase the prospect of focal spermatogenesis in the testis, despite the failure to identify mature spermatids in the specific testicular biopsy under examination.

Adult↗
PubMed2000

Sperm ultramorphology as a pathophysiological indicator of spermatogenesis in males suffering from varicocele.

Varicocele of spermatic veins is considered to be one of the major causes of male infertility associated with reduction of sperm quality. The pathophysiology of this condition is not yet completely understood. The aim of this study was to shed light on the pathophysiology of varicocele by identifying semen parameters, especially sperm ultramorphology, which improve following high ligation of the spermatic vein. Seventy-five males with diagnosed varicocele were included in this study. Semen parameters were assessed prospectively using light microscopy, semen biochemistry and sperm quantitative ultramorphological analysis, before high ligation and 3-9 months after high ligation. The control group consisted of twenty-five untreated varicocele patients who underwent two semen examinations within 3-9 months. No statistical difference in any of the examined variables was found between the two examinations in the control group. The treated patients exhibited a significant improvement in sperm density, progressive motility, percentage of normally formed spermatozoa, agenesis of sperm acrosome, chromatin condensation and incidence of amorphous heads compared with the pretreatment condition (P < or = 0.01). In contradiction, no significant improvement was observed following treatment in any of the sperm tail subcellular organelles. It is concluded that varicocele may cause deleterious alterations in early spermatid head differentiation during spermiogenesis and that varicocele patients with a high incidence of sperm acrosome and nucleus malformations are appropriate candidates for varicocele correction.

Adult↗