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Biomedical subjects

G Paz

Publications and source records attributed to G Paz.

At least 19 recordsLinked to original sources
PubMed1999

Pre-freezing sperm preparation does not impair thawed spermatozoa binding to the zona pellucida.

The present study was conducted to assess the fertilizing potential of frozen-thawed spermatozoa, which were cryopreserved after separation on a Percoll gradient, or washed out of seminal plasma. For this purpose, binding to the zona pellucida and other characteristics of the treated sperm cells were compared with those of cryopreserved spermatozoa from the same original sample which were not manipulated before freezing. Semen specimens were obtained from 80 candidates for sperm donation. Percoll-treated sperm samples compared with the sibling, unprocessed controls had significantly higher values of sperm motility characteristics and per cent of cells with normal morphology after freezing and thawing. Sperm binding ability to the zona pellucida was not statistically different (109 +/- 8.1% and 94 +/- 6.7% in unprocessed and Percoll-treated samples respectively). Sperm specimens processed by washing had significantly higher values for motility characteristics than untreated sibling samples, but no differences were found between the treated and untreated samples for morphology and binding to the zona pellucida (hemizona index of 75 +/- 7.0% and 76 +/- 6.7% in unprocessed and washed samples respectively). These findings suggest that, judged by the binding assay, the aforementioned pre-freezing separation processes have no adverse effect upon the fertilizing potential of the thawed sperm cells. These procedures make it possible to optimize the progressive motile sperm cell concentration of the frozen specimen, which facilitates the storage of samples with good quality, even when the features of the original semen are sub-optimal.

Cell Separation↗
PubMed1999

Genetic evaluation of infertile men.

Recently, microdeletions in the azoospermic factor region of the Y chromosome, in addition to chromosomal anomalies, have been detected in men with azoospermia or severe oligozoospermia. In this study we evaluated the molecular and cytogenetic defects of infertile men. The frequency of Y microdeletions among 105 azoospermic, 28 oligozoospermic and 32 fertile men was tested on lymphocyte DNA using a series of 20 sequence-tagged sites. In addition, microdeletions were evaluated on testicular-derived DNA among 26 azoospermic patients who underwent testicular biopsy and in whom no sperm cells could be identified. Karyotype analysis was performed on 72 of the infertile patients. Deletions were detected in 6.7% azoospermic and 3.6% oligozoospermic men. No deletions were identified among the fertile men. Identical results were obtained with DNA derived either from lymphocytes or testicular tissue. The frequency of chromosomal aberrations in the 72 infertile patients tested (62 azoospermic, 10 oligozoospermic) was 16.6%, with a high percentage of gonosome anomalies. Additional andrological parameters (hormone values, cryptorchidism) failed to identify men at risk for having microdeletions before the test. Our findings support the recommendation to perform genetic defect screening among infertile men before their enrollment in an intracytoplasmic injection/in-vitro fertilization programme.

Adult↗
PubMed1998

Increased rate of nondisjunction in sex cells derived from low-quality semen.

The relationship between chromosomal nondisjunction and semen quality was studied in two groups of males who differ highly in their semen quality: 12 individuals with low-quality semen caused by varicocele, and 8 subjects with high-quality semen, selected from sperm donors for in vitro fertilization. Chromosomal nondisjunction was inferred from the rate of disomy found in mature sperm cells. To determine the rate of disomy, we applied fluorescence in situ hybridization using satellite-specific probes for chromosomes 1, 15, 18, X and Y. In sperm cells of males with low-quality semen, the mean rate of disomy for each of the autosomes and of hetero-disomy for the sex chromosomes (XY) was significantly higher than that observed in the high-quality semen samples: more than 15-fold higher for chromosomes 1 and 15, and 7-fold higher for chromosomes 18 and XY. Yet, the homo-disomy rate for each of the sex chromosomes (XX and YY) was almost the same in both types of semen. The large discrepancy between the low- and high-quality semen in the rate of sex chromosome hetero-disomy versus the similar rate of homo-disomy strongly suggests that the abnormal chromosomal segregation in meiocytes of males with low-quality semen resulted from chromosomal nondisjunction at the first meiotic division. The results indicate that men showing poor semen quality are at an increased risk for meiotic nondisjunction, similar to women at the end of their reproductive years.

Adult↗
PubMed1998

Expression of mannose-ligand receptors on human spermatozoa: effect of lecithin and association with sperm binding to the zona pellucida.

OBJECTIVE: To evaluate the change in the expression of mannose-ligand receptors and sperm binding capacity after the incubation of sperm cells with lecithin liposomes. DESIGN: A randomized, blinded-controlled experiment. SETTING: Andrology laboratory at the Lis Maternity Hospital. PATIENT(S): Fifteen fertile sperm donors and 10 subfertile men. INTERVENTION(S): Incubation of sperm samples with either control medium or 1 mg/mL of liposomal lecithin for 2 hours. MAIN OUTCOME MEASURE(S): Expression of mannose-ligand receptors as evaluated by mannosylated bovine serum albumin-fluorescein isothiocyanate and sperm binding to the zona pellucida as evaluated by the hemizona assay. RESULT(S): The mean +/- SE percentages of spermatozoa with patterns I, II, and III were 86% +/- 4.8%, 11% +/- 3.4%, and 3% +/- 1.6%, respectively, after treatment with control medium and 71% +/- 5.7%, 22% +/- 3.5%, and 7% +/- 2.5%, respectively, after treatment with lecithin. The same effect of lecithin was observed in the 10 sperm samples from subfertile men. The mean +/- SE numbers of sperm that bound to hemizonae after treatment with control medium or lecithin were 116 +/- 32.4 and 176 +/- 29.6, respectively. Statistically significant correlations were observed between the shift in patterns II and III and the enhancement of sperm binding after lecithin treatment (r = 0.44 and 0.6, respectively). CONCLUSION(S): Lecithin shifts the expression of mannose-ligand receptors to the capacitated and acrosoine-reacted patterns and enhances the binding capacity of the sperm cells.

Adult↗
PubMed1998

Multiple testicular sampling in non-obstructive azoospermia--is it necessary?

Spermatogenesis may be focal in non-obstructive azoospermia. The present study was conducted to determine whether the performance of multiple, rather than a single testicular sample contributes to obtaining spermatozoa in amounts sufficient for fertilization and cryopreservation in non-obstructive, azoospermic patients. Furthermore, the aim was to clarify the significance of location for retrieval from the testis in such cases. Three biopsies were taken from identical locations in 55 testes of 29 men with non-obstructive azoospermia: (i) the rete testis region, ii) the midline, and (iii) the proximal region of the testis. When sperm cells were detected, they were used for intracytoplasmic sperm injection (ICSI), and the remainder were then cryopreserved in as many aliquots as possible (adjusted for ICSI procedure). Spermatozoa were found in 28 testes (50.9%) of 18 men (62.1%). In the testes from which spermatozoa were obtained, they were present in three, two or one locations in 15 (53.6%), five (17.9%) and eight (28.6%) cases respectively. The possibility of finding spermatozoa was not influenced by the location in the testis. Multiple testicular sperm extraction is recommended in cases of non-obstructive azoospermia, since it may enhance diagnostic accuracy of absolute testicular failure and increase the number of sperm cells retrieved.

Adult↗
PubMed1997

Sperm quality in Hodgkin's disease versus non-Hodgkin's lymphoma.

The study was conducted to determine the deleterious effect of lymphoma disease on spermatogenesis and to evaluate the possibility that the disease is mediated primarily by inherent mechanisms in Hodgkin's disease and non-Hodgkin's lymphoma patients. A total of 89 patients with lymphoma disease (Hodgkin's and non-Hodgkin's) were referred for sperm preservation prior to adjuvant treatments. A comparison was made of pre- and post-thaw sperm quality between lymphoma patients and healthy volunteers who applied for sperm donation. This was followed by further assessment of the differences between patients with Hodgkin's disease and non-Hodgkin's lymphoma in terms of sperm variables, clinical parameters and blood hormone concentrations. It was found that patients with lymphoma disease had significantly impaired pre-freeze and post-thaw sperm quality compared with that of healthy volunteers. Patients with non-Hodgkin's lymphoma had spermatozoa of higher quality than patients with Hodgkin's disease. No differences were found in the clinical or hormonal parameters between these two groups. As expected, reduced testicular size and abnormal testicular consistency were correlated with decreased sperm quality. The mere presence of cancer disease has a direct negative effect on spermatogenesis, which is probably not related to incidental side-effects. A variable degree of impairment should be expected with different categories of cancer.

Adolescent↗
PubMed1997

Testicular cancer and spermatogenesis.

We retrospectively analysed the characteristics of 54 men with testicular cancer. The group comprised 32 men with pure seminoma and 22 with non-seminoma germ cell tumours (NSGCT). This group was further compared to 190 healthy sperm donor candidates. Sperm quality was found to be higher in the seminoma versus the NSGCT patients in: sperm concentration [50 (0-230) versus 17 (0-288) x 10(6)/ml, P < 0.001], total motile sperm counts (TMC) [57 (0-508) versus 12 (0-854) x 10(6)/ejaculate, P = 0.002], post-thaw forward motile concentration [3 (0-28) versus 1.7 (0-17) x 10(6)/ml, P = 0.003] and motility percentage [20 (0-57) versus 12.5 (0-42) %, P = 0.002]. Serum hormone concentrations did not differ between these two sub-groups, although the follicle stimulating hormone concentrations were higher than normal in both (14.6 +/- 2.5 versus 10.4 +/- 1.4 mIU/ml, P > 0.05). As is well documented, cancer patients were found to have lower sperm quality compared to healthy candidates. The existence of these differences, and the fact that testicular cancer affects spermatogenesis, indicated that the mechanisms involved in the deterioration of sperm quality can, at least partially, be attributed to the type and origin of the malignant cancer. The higher sperm counts in the seminoma group may be related to the fact that the resemblance of the seminoma cells to normal germ cells is greater than that of the NSGCT cells, and therefore they retain a better capacity to function. Due to modern assisted reproductive technologies and micromanipulation achievements, the lower yield of spermatozoa in severe cases is no longer a major obstacle to offering cryopreservation to these patients.

Cryopreservation↗
PubMed1997

Reduction of sperm cholesterol:phospholipid ratio is a possible mechanism for enhancement of human sperm binding to the zona pellucida following incubation with phosphatidylcholine liposomes.

TEST (TES (N-tris[hydroxymethyl]methyl-2-aminoethanesulfonic acid) and Tris) yolk buffer (TYB) has recently been shown to improve the binding capacity of spermatozoa to zona pellucidae. The present study had two objectives: 1) to elucidate which component(s) of TYB dominates this effect and 2) to define the responsible mechanism. Sperm samples obtained from subfertile men were incubated for 2 h in either TYB or media containing egg yolk lipoproteins or phospholipids. After incubation, sperm binding was tested by the hemizona assay. Yolk lipoprotein-treated spermatozoa bound hemizonae with efficiency equal to that of the spermatozoa incubated in control medium. Conversely, incubation of spermatozoa in media containing either TYB, yolk-phospholipids, or pure phosphatidylcholine (PC) resulted in a 2- to 3-fold increased binding capacity (p < 0.01). A close correlation was found between the effect of yolk-phospholipids and TYB on the binding capacity of the same sperm samples, compared to spermatozoa incubated in control medium. Incubation of spermatozoa in yolk phospholipid medium caused a dose-dependent increase of sperm binding capacity (p < 0.05). Treatment of sperm samples with 1 mg/ml or more of purified PC preparation also resulted in a reduction of the sperm cholesterol:phospholipid molar ratio. Significant correlations between the effects of the treatments on sperm cholesterol: phospholipid molar ratio and sperm binding were obtained with yolk-phospholipids (r = -0.55) or 1 mg/ml purified PC (r = -0.61). We conclude that 1) the enhanced binding capacity of human spermatozoa following TYB treatment is probably due to yolk-phospholipids, mainly egg yolk PC; and 2) it appears that the enhanced binding capacity of human spermatozoa following treatment with egg yolk-containing media may be a result of the reduction of the cholesterol:phospholipid molar ratio in the sperm cells.

Acrosome↗
PubMed1995

The use of hemizona assay in the evaluation of the optimal sperm preparation technique.

The objective of the study was to evaluate the benefit of different sperm preparation methods by using the hemizona assay. A total of 58 men admitted to the male infertility clinic for evaluation were tested by routine semen analysis and hemizona assay. Five different techniques (swim-up, TEST-yolk buffer, Percoll, pentoxifylline and progesterone) were used for preparation of sperm suspensions. The effect of these treatments on the sperm-binding capacity using the hemizona assay was assessed. The routine swim-up preparation was used as the reference method. Of the four preparation methods, only the TEST-yolk buffer and pentoxifylline exhibited an overall statistically significant improvement in sperm-binding capacity in comparison with the swim-up preparation method (P = 0.01 and 0.001 respectively). Following preparation with Percoll and progesterone there was no change in the mean value of binding capacity, compared with swim-up. However, examination of the effect of the four treatments on each specimen individually yielded a diversity in the response, e.g. having the capability to enhance, damage or be ineffective in sperm binding capacity. The results support the conclusion that in-vitro sperm preparation methods can affect sperm binding to the zona pellucida. Since there is a diversity in the response of sperm samples to different treatments, the hemizona assay can be used in selecting the optimal sperm preparation method prior to its use for assisted reproductive techniques. This is advocated mainly for the 'male factor' group.

Cell Separation↗
PubMed1995

Female age does not affect the capacity of human zona pellucida to bind spermatozoa.

The purpose of this study was to evaluate the effect of female age on the capacity of the zona pellucida to bind spermatozoa. A total of 1008 unfertilized oocytes obtained from 210 women (aged 21-43 years) participating in the in-vitro fertilization programme were tested using a hemizona assay. Spermatozoa taken from a cryopreserved pool of fertile donor specimens served as a control in the hemizona assay, and were used to assess the ability of the zona pellucida to bind spermatozoa. The mean +/- SD number of spermatozoa attached to the hemizona was 107 +/- 42. The binding capacity of different oocytes from the same cohort varied substantially (coefficient of variation = 28%). Age was not found to be correlated with the number of spermatozoa bound to the zona pellucida (r = -0.02; P > 0.1). It was concluded that female age has no role in the ability of the human zona pellucida to bind spermatozoa.

Adult↗
PubMed1995

Immigrant families coping with schizophrenia. Behavioral family intervention v. case management with a low-income Spanish-speaking population.

BACKGROUND: This investigation compared the effectiveness and cross-cultural applicability of behavioural family management (BFM) and standard case management in preventing exacerbation of symptoms and relapse in schizophrenia. METHOD: Forty low-income Spanish-speaking people with a diagnosis of schizophrenia were randomly assigned to receive standard case management or behavioural family management after stabilisation with neuroleptic medication. RESULTS: Survival analyses indicated that among the less acculturated patients BFM was significantly related to greater risk of exacerbation of symptoms. Among the more acculturated patients, risk of exacerbation could be predicted by medication compliance but not by type of intervention. In analyses of symptom severity and functional status at 1-year follow-up, the level of patient acculturation was found to be significantly related to various measures of treatment outcome. CONCLUSION: Sociocultural factors affect responses to different types of intervention. The results did not support earlier findings of a beneficial effect of BFM when applied to a socioculturally diverse population.

Acculturation↗
PubMed1995

Pentoxifylline improves sperm binding to the zona pellucida in the hemizona assay.

OBJECTIVE: To evaluate the effect of pentoxifylline on sperm binding capacity to zona pellucida (ZP) using the hemizona assay (HZA). DESIGN: The fertility potential of 82 men was evaluated by routine semen analysis. Each ejaculate was incubated with or without pentoxifylline (3 mM) in Ham's F-10 medium (Flow Laboratories, Irvine, Scotland) before the HZA. The effect of the pentoxifylline treatment on sperm-binding capacity to ZP was assessed by the hemizona index. RESULTS: The mean hemizona indexes with medium or pentoxifylline treatment were 23% +/- 2.1% (mean +/- SE) and 41% +/- 3.4%, respectively. Taking into consideration a significant change of the hemizona index on rising above the intra-assay coefficient of variation (+/- 8%) after pentoxifylline treatment, 73.1% of specimens improved, 19.5% deteriorated, and 7.4% remained unchanged. Using a threshold hemizona index of 23% as a discriminator between fertile and infertile specimens, 43.5% of the "pentoxifylline-improved" samples ascended to the fertile zone (> 23%). No correlations were found between sperm variables in the raw semen and the effect of pentoxifylline on sperm binding capacity. CONCLUSION: Pentoxifylline may improve the binding capacity of human spermatozoa. However, this effect is confined to a selected group of patients and cannot be predicted by the basic sperm variables. Thus, to avoid uncertain or damaging effects of pentoxifylline while preparing sperm suspension for assisted reproductive techniques, it is recommended that its effect be tested by the HZA system before its use.

Female↗
PubMed1994

Blood luteinizing hormone and prolactin concentrations in response to naltrexone challenge: studies on rats with diabetes induced by different doses of streptozotocin.

Opiate system involvement in diabetes induced by three different doses of streptozotocin (STZ; 40, 50, and 60 mg/kg body weight [BW]) was studied by monitoring luteinizing hormone (LH) and prolactin (PRL) levels as a response to naltrexone (Nalt) administration. After four weeks of diabetes a marked decrease in BW, as well as severe hyperglycemia and increased blood urea nitrogen (BUN) levels were found. The rats, whose diabetes was induced by 50 mg/kg of STZ, exhibited the highest amount of blood glucose (P < 0.05, compared with the 40 mg/kg induced group) and BUN levels (P < 0.004 compared with the other two groups) and BW loss. The normal response to Nalt, which is expressed by elevation of plasma LH and decreased plasma PRL levels was observed only in the low-dose STZ (40 mg/kg BW) diabetes-induced group, while in the other two diabetic groups (50 and 60 mg/kg BW) there was no significant change in plasma LH and PRL as a result of the Nalt challenge. Presensitization of the endogenous opioid receptors by morphine in normoglycemic (control) and "low-dose diabetic" rats (40 mg/kg BW of STZ), presented a clear difference between the two. Morphine pretreatment inhibited LH response to Nalt in the low-dose, STZ-induced diabetic rats, while no effect of morphine pretreatment on LH response to Nalt could be recorded in the normoglycemic group. Thus it can be concluded that in STZ-induced diabetes, plasma glucose and BUN levels do not reflect the neuroendocrine injury observed when monitored by LH and PRL secretion in response to Nalt challenge. Supersensitization of the opioid receptors before the Nalt challenge may increase the ability to reveal neuroendocrine system impairment.

Animals↗
PubMed1994

The effect of egg yolk on the binding capacity of human spermatozoa to zona pellucida.

OBJECTIVE: To evaluate the effects of Tes and Tris (TEST)-yolk buffer (TYB) incubation on sperm function. DESIGN: Sperm samples obtained from 61 patients attending the infertility clinic were incubated in TYB and control medium. Binding to the zona pellucida (ZP), evaluated by the hemizona assay, membrane functional integrity evaluated by the hypoosmotic swelling test, and acrosome reaction and penetration through cervical mucus were assessed to ascertain the effect of TYB treatment. RESULTS: The only substantial effect of TYB treatment was enhanced sperm binding to the ZP. The mean number of sperm cells attached to the hemizonae with TYB or medium treatment, was 42 +/- 6.1 (+/- SE) and 31 +/- 5.8, respectively (n = 61). However, this improvement was most obvious in 12 patients whose sperm samples exhibited a marked increase in sperm binding capacity following TYB treatment compared to medium without TYB, 71 +/- 5.6 and 12 +/- 2.7, respectively. In the other sperm samples (n = 49), sperm binding capacity was similar following TYB and medium treatment (both 35 +/- 6.0). CONCLUSIONS: A 2-hour incubation of sperm samples with TYB-containing medium (at room temperature) enhances the binding capacity of human spermatozoa in approximately 20% of patients considered to have male factor infertility. The basis of this selective effect has yet to be studied further.

Egg Yolk↗
PubMed1994

Retrograde ejaculation.

Retrograde ejaculation is an uncommon cause of male infertility. It should be suspected in any case of azoospermia, and might be congenital, acquired or idiopathic in origin. When pharmacological attempts to restore anterograde ejaculation fail, it is suggested that spermatozoa should be recovered from post-ejaculation urine to be applied in one of the modern techniques of assisted reproduction. The successful recovery of viable spermatozoa from the urine is dependent upon careful regulation of pH and osmolarity of the urine at the time of ejaculation. Careful handling of the retrieved spermatozoa enables isolation of sperm cells with good quality for insemination of ovulated oocytes (in vivo) or retrieved oocytes (in vitro).

Ejaculation↗
PubMed1994

Serum prolactin response to ether stress in diabetic rats: opiate system contribution.

Diabetes in streptozotocin-treated rats is associated with alterations in various neuroendocrine systems, including endogenous opioids. These changes are suggested to be responsible for the significant reduction in serum prolactin (PRL) response to a brief restraint stress in diabetic male rats, as compared with normoglycemic controls. The present study examines serum PRL response to ether exposure in diabetic male rats. The animals' response to ether stress, which is known to be related to the opioid system, was examined twice in each rat: shortly after cannula insertion (Day 1), and seven days later. In order to evaluate the opiate system involvement, the experiment was repeated on Day 1 and 7 after surgery in a group of rats which were pretreated with naltrexone (Nalt), an opioid receptor antagonist. Opioid receptor sensitization was also performed by prior acute morphine administration on Day 7 after cannulation surgery. Following adaptation to the cannulation, no difference in serum PRL response to ether stress was found between diabetic and normoglycemic rats. However, on Day 1 after surgery, a significant difference was found between the diabetic and control groups: the normoglycemic (control) group exposed to ether responded to the surgical stress by augmented serum PRL levels. This response was not recorded in the diabetic rats. Opioid receptor blockade by Nalt administration 30 min before ether exposure eliminated this difference. Opioid receptor sensitization by morphine pretreatment facilitated PRL secretion in normoglycemic rats exposed to either, while no effect could be distinguished in the diabetic group. It is therefore concluded that the streptozotocin-induced diabetic rats do not differ from normoglycemic ones in their ability to respond to acute ether stress by itself. However, enhanced PRL secretion induced by ether exposure under additional surgical stress, or by presensitization of the opioid receptors by morphine, is prevented in diabetic rats, probably due to diminished opioid receptor response.

Animals↗
PubMed1993

[Hemizona assay for evaluating fertilizing capacity of human spermatozoa].

The hemizona assay (HZA), which tests the binding capacity of human spermatozoa to the zona pellucida, is described. This assay has very high sensitivity (86-100%) in predicting fertilizing capacity in the in vitro fertilization (IVF) system. It is recommended that it be carried out on semen samples before entering the IVF program. In addition, it can also help evaluate unexplained infertility and assess the quality of ova. The necessity for a control fertilized sample in each HZA might complicate the assay. To simplify the test, the use of sperm from the sperm bank was investigated. It was shown that fresh and frozen-thawed sperm have the same capacity to bind to the hemizonae. Thus, frozen donor semen preserved in the sperm bank can be used for controlling the HZA.

Cryopreservation↗