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Biomedical subjects

L Yogev

Publications and source records attributed to L Yogev.

88 records · Page 5Linked to original sources
PubMed1980

Daily rhythm in secretion of prolactin in androgenized female rats.

Androgen-sterilized female rats were obtained by administering 10 micrograms testosterone propionate to pups on day 2 after birth. In contrast with ovariectomized adults, androgenized adult female rats are incapable of responding to cervical stimulation by secreting prolactin in the nocturnal surge pattern. In spite of the loss of this pattern the androgenized female rats still exhibited a daily circadian rhythm of prolactin secretion with afternoon levels three times higher than those after midnight.

Animals↗
PubMedDate not supplied

Probability of sperm detection in nonobstructive azoospermic men undergoing testicular sperm extraction procedures unrelated to clinical parameters.

The study was conducted to evaluate the significance of preoperative clinical parameters for detection of mature testicular sperm cells in nonobstructive azoospermic men. Sixty-five consecutive men with nonobstructive azoospermia underwent testicular sperm extraction procedures. Testicular samples were analyzed histologically with patterns classified as mature spermatogenesis (normal or partial), arrest of spermatogenesis, and Sertoli cell only. Testicular sperm cells were isolated for use in an IVF/ICSI program. Histologic patterns and detection rate of sperm cells were correlated to clinical characteristics. Mature sperm cells were found in all levels of serum FSH. The men were divided into 3 groups based on their clinical characteristics (serum FSH level and testicular size). The distribution of the different testicular histologic patterns, as well as detection rate of sperm cells, was similar in all groups. No correlation was found between serum levels of FSH, LH, prolactin, or testosterone and sperm presence. None of these parameters, nor the testicular size and consistency, can serve as predictive variables of the histological pattern or the presence of mature sperm cells in the testicular biopsies in cases of nonobstructive azoospermia. Until an effective predictive tool is available, a trial of sperm retrieval is recommended for all azoospermic men independent of their clinical characteristics.

Adult↗
PubMedDate not supplied

The expression of mannose-ligand receptor is correlated with sperm morphology.

The objective of the present study was to evaluate the association between the expression of sperm mannose-ligand receptors and sperm morphology. Sperm samples were obtained from 45 men, 30 fertile sperm donors and 15 infertile men. Sperm concentration, motility and morphology were evaluated and then incubated with control medium (Ham's F-10 + 1% HSA) for 4 h. Expression of mannose-ligand receptors was evaluated by mannosylated-BSA-FITC (subdivided into 3 patterns: I, for uncapacitated sperm; II, for capacitated; and III, for acrosome-reacted sperm). The mean (+/- SE) frequencies of sperm cells of the total sperm population that expressed patterns I, II, and III were 88 +/- 2.1%, 7 +/- 1.6%, and 5 +/- 0.8%, respectively, for fertile men, and 90 +/- 2.1%, 7 +/- 1.3%, and 3 +/- 0.5%, respectively, for infertile men. The rate of pattern III expression of mannose-ligand receptors was significantly higher in the fertile group compared to the infertile patients (p <.01). A poor but significant correlation was observed between the rate of pattern III and the percentage of normal-forms sperm cell in the ejaculate (r =.35, p =.018). Fertile sperm samples express more advanced patterns of mannose-ligand receptors compared to infertile men. This phenomenon is related to the morphology of human sperm cell in the ejaculate more than to any other basic sperm characteristics.

Humans↗
PubMedDate not supplied

Improvement in the cervical mucus penetration test by using standard sperm control.

The objective of the present experiments was to establish an acceptable standard for the cervical mucus penetration test (CMPT) by determining the minimal progressive motile spermatozoa concentration (PMSC) that will yield the highest score for proven fertile donor sperm specimens. For this purpose, fresh and frozen-thawed samples were used. Semen was obtained from 29 fertile donors and different PMSC (8, 10, and 14 x 10(6)/mL) were prepared for each sample. The same mucus specimen was used for testing each sperm sample in the three different dilutions. No difference in the scoring of the CMPT between the fresh vs. frozen-thawed groups was found. When PMSC of 14 x 10(6)/mL was used, almost all specimens scored the highest rank. The present study revealed that only semen samples with a minimal PMSC of 14 x 10(6)/mL cells can be used in the CMPT. The information that the freeze-thaw process does not affect the CMPT results supports the concept of cryopreservation of pooled fertile donor specimens in aliquots with adequate concentration of progressive motile spermatozoa for later use as a CMPT control.

Cervix Mucus↗
PubMedDate not supplied

Varicocele: effect on sperm functions.

Despite the numerous studies published over the past decade, the role of varicocele in male infertility is still controversial. Although more frequent in infertile men, its influence on sperm production or function has not, as yet, been determined. Moreover, the exact mechanism of varicocele action is not clear. We have surveyed the literature, the correlation of varicocele to sperm parameters and to sperm function tests, such as binding capacity, hypo-osmotic swelling test, presence of reactive oxygen species, and in particular, the correlation to fertility potential. Almost every subject examined had contradictory results. Larger control studies may possibly elucidate and clarify the cases in which varicocele is associated to sperm function, and where treatment may improve fertility.

Acrosome Reaction↗
PubMedDate not supplied

Intrauterine insemination in subfertile couples.

Forty-three subfertile women were treated by intrauterine insemination with washed sperm. Among the couples, infertility was, in 7 cases due to cervical factor infertility, in 17 cases due to subfertile sperm quality, and 19 cases, unexplained. All women ovulated: 9 spontaneously, 26 where treated with clomiphene citrate and 8 with hMG-hCG. One hundred and sixty seven inseminations were performed in 90 ovulatory cycles. Six pregnancies were recorded (14%): three pregnancies among the cervical factor infertility group (42.8%), two among the couples with low sperm quality (11.7%) and one pregnancy in the group with unexplained infertility (5.2%). Thus, it can be concluded that IUI is effective for achieving pregnancy when unfavourable cervical factor is detected. The method is of doubtful value in cases of low sperm quality or unexplained infertility.

Adult↗
PubMedDate not supplied

Fertility of men following inguinal hernia repair.

Among 8500 patients attending the fertility clinic due to infertility, 565 men (6.65%) reported an incidence of inguinal hernioplasty with or without subsequent atrophy of the testis. Semen quality (sperm concentrations, motility, and morphology) of these patients was markedly reduced in comparison to that of fertile men. In cases where hernioplasty was followed by atrophy of the testis, damage to sperm characteristics and Sertoli cell function was found to be far greater. This was also reflected in significant serum follicle stimulating hormone elevation (P less than 0.0025). No changes in luteinizing hormone and testosterone were found. No correlation was found between age of hernioplasty and semen quality following operation. The reasons for testicular damage may be due to ischaemic orchitis or immunological reactions.

Adolescent↗
PubMedDate not supplied

Cryptorchidism: incidence and sperm quality in infertile men.

In a population of 8500 men attending the andrology outpatient clinic, 200 men (2.35%) were recorded as having some disturbances with the descent of the testes into the scrotum. Medical history of the patients revealed that 51 underwent unilateral orchidopexy; 40 bilateral orchidopexy; and 24 were treated with human chorionic gonadotropin in order to induce descent of their testes. In addition, 6 patients reported spontaneous descent of the testes, and 13 others were found to be unilaterally cryptorchid upon physical examination. Results of semen analysis, hormonal profile, testes position, and testicular volume were compared to those of 105 proven fertile men. The major finding of this study shows that post-partum undescended testes suffer from primary Sertoli cell malfunction as reflected by elevated serum follicle stimulating hormone levels. Serum luteinizing hormone and testosterone levels were within the normal range. Surgical descent of the testes did not improve sperm production, proved by low sperm quality of all the study groups, compared to the cryptorchid group. Among the patients who were operated on, no correlation was found between age at operation and semen variables. All groups showed poor sperm quality which can be defined as oligoteratoasthenozoospermia. The degree of spermatogenic damage was in the following order of diagnosis or treatment: bilateral orchidopexy greater than cryptorchid testes greater than hormonal treatment greater than unilateral orchidopexy greater than late spontaneous descent of the testes. Thus, it is advisable to postpone surgical treatment of cryptorchidism and apply this only after a waiting period, and if the hormonal approach has failed to descend the testis.

Adolescent↗
PubMedDate not supplied

Advanced methods for evaluation of sperm quality.

Routine semen analysis includes measurements of sperm concentration, motility, and morphology. In our study, three additional tests were evaluated in relation to fertilization rate in an in vitro fertilization program: the freezing and hypo-osmotic swelling tests that evaluate the functional integrity and stability of the sperm membrane under extreme osmotic conditions, and migration sedimentation test that isolates high-quality motile sperm cells. The study was performed on semen delivered by men of couples treated at the In Vitro Fertilization Unit, and men who served as semen donors (fresh or cryopreserved semen). No correlation was found between the sperm fertilization rate, and the decrease in motility percent following the freezing-thawing process. Thus, the freezing test cannot be used to predict semen fertilization capacity. The hypo-osmotic swelling test was applied on semen given by a similar population of men. While the hypo-osmotic swelling test values carried out with fresh semen was found to have good correlation with fertilization, no correlation was found when frozen thawed semen was used. Post-migration sedimentation test sperm characteristics, and especially the recovery rate of the motile sperm, were significantly better in in vitro fertilization cycles with fertilizations. Both the hypo-osmotic swelling test and migration sedimentation test can assist in evaluating semen quality, judged by the fertilization rate in an in vitro fertilization program.

Female↗
PubMedDate not supplied

Sperm binding and ultrasound changes after operative repair of varicocele: correlation with fecundity.

The study was conducted to evaluate the changes in sperm binding capacity and ultrasound measurements of the internal spermatic vein, after operative repair of a varicocele. In order to clarify the effect of a varicocele on fertility, these changes were correlated to pregnancy achievement. Twelve infertile males with subnormal semen parameters and varicocele, underwent operative repair. Pre- and post-operatively, all had semen analysis, hemizona assay and ultrasound of the internal spermatic veins. The patients were divided into three subgroups according to pregnancy outcome, and the changes in the different evaluation tests after the operation were compared. Sperm concentration and motility improved post-operatively in all three subgroups, whereas the hemizona index and ultrasonographic measurements improved significantly only in the subgroup that achieved early pregnancies (the mean post-operative percentage of normal morphology was significantly higher), compared to the subgroup without pregnancies. Unlike sperm parameters which improve after operative repair of the varicocele, but have no correlation to conception, sperm binding and ultrasound measurements of the internal spermatic veins improve significantly in cases that achieve early pregnancies. The use of these tests, as well as measuring the percentage of normal morphology, are recommended in all cases of infertility-related varicocele.

Female↗
PubMedDate not supplied

Correlation between sperm penetration into the human zona pellucida and in vitro fertilization rates.

Sperm penetration into the zona pellucida of unfertilized oocytes, and its correlation with in vitro fertilization rates of the sibling oocytes, were assessed. This was performed in order to evaluate the prediction rate of the sperm penetration test into the zona pellucida. Unfertilized oocytes (n = 1872) from 371 cycles were pipetted through a microcapillary, and the remaining sperm cells penetrating the zona pellucida were counted. The mean (+/- SD) number of spermatozoa that penetrated the zona pellucida of unfertilized oocytes was 12.9 +/- 16.37. A significant correlation was found between the fertilization rate and the mean number of spermatozoa that penetrated into the zona pellucida of the unfertilized sibling oocytes (r = 0.48; P < 0.001), or the percent of unpenetrated zonae pellucidae in a cohort (r = -0.43; P < 0.001). However, a distinct variation in the number of spermatozoa that penetrated into the zona pellucida was detected. A step-wise regression analysis proved the number of spermatozoa penetrating the zona pellucida to be more predictive for fertilization rates than the variable of percent of unpenetrated zonae pellucidae. The results imply that although there is interdependence between penetration into the zona pellucida and fertilization rate, the predictive value of sperm penetration test for prognosis and future management after the first in vitro fertilization attempt, is limited.

Cohort Studies↗
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Effect of sperm preparation with TEST yolk buffer on sperm-binding capacity under hemizona assay conditions.

The study was conducted to evaluate the diverse effect and clinical significance of TEST yolk buffer treatment on sperm samples of 128 infertile men. Sperm samples were incubated with TEST yolk buffer and control medium (Ham's F-10) at room temperature for 2 h. The hemizona indices (mean +/- SE) of the TEST yolk buffer and medium-treated sperm samples were 29 +/- 2.3% and 22 +/- 1.6%, respectively. Inspection of the individual response of each sperm sample to TEST yolk buffer revealed that 63 samples (49%) improved (double the interassay variation = 28%) their binding to zona pellucida, 36 (28%) remained unchanged, whereas the binding capacity of 29 samples (23%) decreased. Furthermore, TEST yolk buffer treatment of 24 samples (19%) resulted in an increased binding beyond the hemizona index threshold set up at 23%. This level was previously shown to be the cut-off point between fertile and infertile sperm samples. It was concluded that when applied to an unselected group of infertile men, TEST yolk buffer significantly increased sperm binding capacity to the zona pellucida. However, only 19% of the sperm samples showed improvement with clinical significance. The other sperm samples may have improved, remained unchanged or even deteriorated independently on basic sperm variables. Thus, the effect of TEST yolk buffer treatment on sperm binding should be tested prior to its clinical use to avoid possible damage to certain sperm samples.

Buffers↗
PubMedDate not supplied

Three-generation evaluation of Y-chromosome microdeletion.

Sperm cells can be retrieved directly from the testis (testicular sperm extraction [TESE] procedure) and used for intracytoplasmic sperm injection (ICSI), circumventing underlying spermatogenetic defects. Thus, it is important that added information be available on the genetic defects in men undergoing TESE for the ICSI procedure and on the transmission of genetic factors associated with infertility to the offspring. We report a three-generation genetic analysis of a family with a case of male factor infertility. The proband, previously diagnosed as infertile, was physically examined and laboratory tested for gonadotrophic hormones, semen analysis, karyotype and Y-chromosome microdeletion screening in the blood and testis. The Y-chromosome microdeletion screening was performed by multiplex polymerase chain reaction with 20 Y-chromosome sequenced, tagged sites located at the Y chromosome. A microdeletion including the AZF-c region was detected in the azoospermic patient. His father, four brothers, and three offspring born after ICSI also underwent Y-chromosome microdeletion screening. The genetic analysis of the male members of the patient's family did not reveal similar microdeletions. The newborn male was found to bear a Y-chromosome microdeletion similar to that of his father. The fertilization capacity of the proband testicular microdeleted spermatozoa by the ICSI procedure is described. The transfer of the genetic defect raises the possibility that the son will have the same fertility problem as his father.

Adult↗
PubMedDate not supplied

Morphology of testicular spermatozoa obtained by testicular sperm extraction in obstructive and nonobstructive azoospermic men and its relation to fertilization success in the in vitro fertilization-intracytoplasmic sperm injection system.

The aim of the present study was to evaluate the morphology of testicular spermatozoa by 3 different determinants. Sperm cells were obtained and their morphology was evaluated from 27 testicular sperm extraction (TESE) operations, of which 20 men had nonobstructive azoospermia and 7 had obstructive azoospermia. In 17 cases, 2 biopsies were obtained from 2 different locations of the testis. Only mature spermatozoa presenting full-grown tail (tail dimension about 10-fold greater than the head dimension) were counted. Three characteristics of sperm morphology were evaluated: head dimensions, and acrosome and midpiece irregularities. The percentage of sperm cells with normal morphology (considering the 3 characteristics) in specimens from patients with obstructive and nonobstructive azoospermia were 47% +/- 4.6% and 29 +/- 1.8%, respectively (P < .01). The percentage of spermatozoa with normal head dimensions were 76% +/- 3.2% and 63% +/- 2.6% (P > .05), those with normal acrosome were 58% +/- 4.6% and 41% +/- 3.4% (P < .05), and those with normal midpiece were 74% +/- 4.1% and 67% +/- 1.6% (P > .05), in obstructive and nonobstructive azoospermia, respectively. No significant differences were observed in sperm morphology between different locations of the testis. Sperm morphological characteristics were not associated with fertilization rate in intracytoplasmic sperm injection (ICSI). Follicle-stimulation hormone and luteinizing hormone were inversely correlated with normal morphology of testicular spermatozoa (r = -0.49 and r = -0.47, respectively; P < .05). It can be concluded that a relatively high portion of testicular sperm are morphologically normal. The higher rate of normal spermatozoa in obstructive azoospermia compared with nonobstructive spermatozoa suggests that the factors leading to azoospermia may affect testicular sperm morphology. The morphological characteristics of testicular sperm do not affect fertilization rate in ICSI.

Adult↗