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Biomedical subjects

S Hamamah

Publications and source records attributed to S Hamamah.

51 records · Page 3Linked to original sources
PubMed1993

1H nuclear magnetic resonance studies of seminal plasma from fertile and infertile men.

Glycerylphosphorylcholine (GPC), glycerylphosphorylethanolamine (GPE), citrate, and lactate content of human seminal plasma was analysed by measuring the peak area of 1H nuclear magnetic resonance (NMR) spectra in samples from four groups of patients: 21 spermatogenic failure subjects; 14 obstructive azoospermic subjects (vasectomized); seven patients presenting very severe oligoasthenozoospermia (OAT) and 18 normozoospermic subjects (control). The peak areas for GPC, citrate and lactate in seminal plasma were significantly smaller for patients with azoospermia than for the control group: 16.79, 8.18 and 2.28 versus 23.38, 10.58 and 4.30, respectively (P < 0.01). The peak area ratios for citrate:lactate and GPC:lactate were significantly different (P < 0.01) between the control group and the spermatogenic failure or obstructive azoospermia groups. A significant difference was also found in GPE:GPC peak intensity ratio between spermatogenic failure and obstructive azoospermia subjects (P < 0.001). These results provide some quantitative markers which may be used for examining infertility by using 1H NMR of seminal plasma samples.

Biomarkers↗
PubMed1993

[Investigation of seminal plasma. Value of nuclear magnetic resonance].

The purpose of this study was to investigate whether the measurement by NMR of some biochemical markers such as glycerylphosphorylcholine (GPC), glycerylphosphorylethanolamine (GPE), citrate, and lactate in human seminal plasma may be able to differentiate spermatogenic failure from obstructive azoospermia. The peak area ratios citrate/lactate, between normozoospermic and spermatogenic failure or obstructive azoospermia groups were significantly different. We have also found significant differences in GPE/GPC peak intensity ratio between spermatogenic failure men and obstructive azoospermia patients (P < 0.001). This ratio appears to be a very important parameter to differentiate spermatogenic failure from obstructive azoospermia. These results demonstrate the potential use of 1H NMR on human seminal plasma in male infertility evaluation and such analysis may be used to elucidate the molecular basis of the human pathologic seminal plasma disturbances.

Anticoagulants↗
PubMed1991

Does in vitro capacitation alter chromatin stability of ejaculated human spermatozoa? Cytochemical studies.

In vitro capacitation of human spermatozoa is commonly evaluated by the progressive motility percent. However its effects on sperm chromatin have hardly been studied. Our aim was to determine the extent to which in vitro capacitation with two treatments (B2 or human follicular fluid) alters the chromatin of human spermatozoa, by using two analytical methods, acridine orange staining and Feulgen-DNA cytophotometric measures. Ejaculates were obtained from 23 men participating in our in vitro fertilization program, and several measurements were made on the same ejaculate for each subject. No alteration was observed for the percent of native DNA after capacitation in B2, but spermatozoa incubation during the same time in human follicular fluid was followed by a significant decrease of the percent of native DNA (P less than 0.01). Feulgen-DNA content significantly increased after capacitation in either B2 or follicular fluid (P less than 0.05, P less than 0.001 respectively), and so did sperm nuclear surface area (P less than 0.001). In this study we observed a negative correlation between Feulgen-DNA content and fertilization rate (P less than 0.02). Moreover, the greater effects on Feulgen-DNA content were observed in men with abnormal sperm, whose spontaneous percent of native DNA was lower (P less than 0.05) and Feulgen-DNA content higher (P less than 0.05) than in men with normal sperm. These results indicate that capacitation in B2 as well as in human follicular fluid may alter the chromatin stability of human spermatozoa. Such results suggest a partial decondensation state of human spermatozoa during in vitro capacitation. However, beyond some level of decondensation, the fertilizing ability could be altered.

Acridine Orange↗
PubMed1991

Chromatin alterations induced by freeze-thawing influence the fertilizing ability of human sperm.

A previous cytochemical study revealed that chromatin alterations could be induced in frozen-thawed human sperm. In order to evaluate the biological consequences of such chromatin alterations, we evaluated the relationship between these chromatin alterations and the drastic decrease or loss of sperm fertilizing ability after freeze-thawing. Using acridine orange staining and Feulgen-DNA quantitative microspectrophotometry, the nuclear variables of sperm were compared using samples which had either recovered, or lost their fertilizing ability after freezing-thawing during artificial inseminations, despite good post-thaw motility. There was a clear decrease in Feulgen-DNA content and nuclear surface values in sperm which exhibited a loss of fertilizing ability. Thus freeze-thawing may alter the DNA/nuclear protein relationships and impair the fertilizing ability of human sperm.

Acridine Orange↗
PubMed1990

Effects of freezing-thawing on the spermatozoon nucleus: a comparative chromatin cytophotometric study in the porcine and human species.

Freezing-thawing effects on the nuclei of porcine and human spermatozoa were studied by determining native DNA percentage from fluorescence after acridine orange (AO) staining and by analyzing chromatin structure by a quantitative microspectrophotometric study of Feulgen-DNA complexes before and after freezing. The study of boar spermatozoa revealed no alteration in native DNA percentage after freezing. However, native DNA percentage decreased significantly in human spermatozoa. Feulgen-DNA content and sperm nuclear surface area decreased in both species after freezing. These results prompted us to hypothesize an overcondensation of sperm chromatin after freezing-thawing. This overcondensation may be related to the lower conception rates obtained with human and porcine semen after cryostorage via defective decondensation.

Animals↗
PubMed1988

Differential localization of glycoconjugates having affinity for concanavalin A on the surface of the sperm head in the testis, the epididymis, and the ejaculate of the ram.

The localization of Con A receptors on the surface of the head of ram spermatozoa originating from the rete testis, from three regions of the epididymis, or from the ejaculate was investigated using a gold-Con A labelling technique. Electron microscopic observation revealed three major localizations, each being characteristic of the origin of the spermatozoa: periacrosomal in the rete testis, postacrosomal in the epididymis, on the entire surface of the sperm head in the ejaculate.

Animals↗
PubMed1988

Freezing and thawing alter chromatin stability of ejaculated human spermatozoa: fluorescence acridine orange staining and Feulgen-DNA cytophotometric studies.

Cryopreservation and freezing-thawing effects on the fertilizing ability of human spermatozoa commonly are evaluated by post-thaw motility. Various studies have depicted the ultrastructural changes caused by freezing-thawing, yet the chromatin alterations have been studied very limitedly. Our aim was to determine the extent to which freezing-thawing alters the chromatin of human spermatozoa, using two analytical methods: acridine orange staining and Feulgen-DNA cytophotometric studies. Both methods revealed a dramatic effect of freezing-thawing on sperm chromatin: the native DNA content decreased as did the Feulgen-DNA content, and sperm surface area was reduced. These results indicate an effect on DNA, diminished accessibility for Feulgen, and a decrease in nuclear surface area and prompt us to hypothesize a relationship between an "overcondensation" state for sperm chromatin after freezing-thawing and a lower conception rate for human semen after cryostorage.

Acridine Orange↗
PubMedDate not supplied

Cryopreservation of spermatozoa: a 1996 review.

Both the ability to freeze human spermatozoa and the possibility of pregnancy following intrauterine insemination have existed for >40 years. There have been a number of improvements during that time concerning the methods of freezing and thawing human spermatozoa. Initially, the use of the cryoprotective properties of glycerol allowed a major improvement; subsequently, changes were mainly empirical. It was a long time before specific cryobiological studies were undertaken. However, the necessity for these became apparent with the partial recovery or sometimes loss of motility after freezing either subfertile semen before chemotherapy or radiotherapy, or spermatozoa collected from non-physiological situations (epididymal or testicular spermatozoa). The main trends in improvement have defined end-points other than the percentage of motility recovery or the assessment of ultrastructural damage. More sensitive criteria of the objective assessment of motility, energy status, damage to the plasma membrane or to subcellular elements, chromatin stability and chromosomal damage have been proposed as complementary end-points to better assess sperm cryopreservation. A different approach was related to the biochemical environment and physical conditions imposed on spermatozoa during the freezing and thawing process. Biochemical changes were assessed following different combinations of various extenders which attempted either to better preserve some parameter or to avoid the tendency towards drastic increase in osmotic pressure. Analysis of physical conditions was linked to the rate of cooling, freezing and warming, and was based on cryobiological studies. Finally, even though such improvements are not negligible, many questions remain unanswered. The extensive use of frozen spermatozoa during assisted reproductive techniques, together with the development of assisted fertilization using surgically collected spermatozoa, creates the need for additional studies to improve the cryopreservation of human spermatozoa.

Cryopreservation↗
PubMedDate not supplied

The effect of male factors in repeated spontaneous abortion: lesson from in-vitro fertilization and intracytoplasmic sperm injection.

Between 6.5 and 21% of pregnancies result in spontaneous abortion. The incidence of repeated spontaneous abortion (RSA) is, however, lower: 0.05-1.0% of pregnancies. These values vary, not only according to the populations studied and the means of diagnosing the miscarriages, but also to the age and the parity of the patient: 4% at 20 years of age versus 16% after 35 years. These differences are greater if biochemical pregnancies are taken into account. The aetiologies of RSA are multiple and at times even multifactorial. While certain aetiologies, such as chromosomal, anatomic, hormonal, immunological or unexplained anomalies, have been extensively explored, the sperm characteristics likely to influence the quality of the conceptus have rarely been examined. This review examines the male factor's contribution in RSA.

Abortion, Habitual↗
PubMedDate not supplied

Stem cell factor/c-kit system in spermatogenesis.

One of the major unresolved questions with male infertility is the identification of the molecular origin of a great majority of the spermatogenetic arrests currently diagnosed as idiopathic male infertility. During the past years, several families of regulating factors have been implicated in spermatogenesis defects observed essentially in animal models. Among these factors are signalling molecules, and particularly the stem cell factor (SCF)/c-kit system. The SCF and its receptor c-kit are an appropriate example to illustrate the role of signalling molecules in the physiology and pathology of spermatogenesis. The SCF/c-kit regulates primordial germ cell migration, proliferation and apoptosis during fetal gonadal development. The SCF/c-kit also regulates spermatogonia proliferation in the adult animal. In mutant mice, abnormalities of the SCF/c-kit gene expression, such as gene deletion, point mutation, alternative splicing defect, lead to different types of spermatogenesis alterations (e.g. decrease in primordial germ cell migration, decrease in spermatogonia proliferation). More recently, defects in SCF/c-kit gene expression have also been shown in human testicular dysfunctions. Indeed, a reduction in SCF/c-kit expression has been evidenced in oligozoospermia/azoospermia associated with an increase in the germ cell apoptosis process. In addition, c-kit seems to be a good marker of seminoma testicular tumours. This review reports a large number of data--obtained essentially in animal models--that suggest an important role for the SCF/c-kit system in spermatogenesis and, as a corollary, its potential involvement in spermatogenic defects.

Animals↗
PubMedDate not supplied

GnRH antagonist in single-dose applications.

Previous studies on ovarian stimulation have confirmed the efficacy of a single dose of the gonadotrophin-releasing hormone (GnRH) antagonist, Cetrorelix, in preventing premature LH surges. The single-dose protocol is easy to use and assures patient compliance. When compared with the long protocol using a depot administration of the GnRH agonist, triptorelin, the IVF results in patients treated with Cetrorelix showed a shorter treatment duration, reduced amount of human menopausal gonadotrophin (HMG) required and a lower occurrence of ovarian hyperstimulation syndrome (OHSS). The pregnancy rates did not differ significantly between the two treatments. The use of Cetrorelix in natural cycles associated with gonadotrophins reduced the rate of premature LH surges and, therefore, the cancellation rate. The stimulation was minimal and the preliminary pregnancy rates were satisfactory. If a larger study confirms the results of the natural cycle with HMG support, the single-dose administration of GnRH antagonist could represent an interesting first-choice IVF treatment in selected indications. The tolerance of Cetrorelix was excellent in all patients, with only mild and transitory reactions at the injection site. New GnRH antagonists are already available for clinical use in some countries, and they will certainly change ovarian stimulation protocols. If the pregnancy rates are confirmed, the main advantages of these new compounds are the reduction in side-effects and complications of the stimulation protocol; a clear benefit to the patients.

Drug Administration Schedule↗
PubMedDate not supplied

Analysis of the lipid content and the motility of human sperm after follicular fluid treatment.

The effect of human follicular fluid (hFF) on the cholesterol and phospholipid content and the movement characteristics of human spermatozoa were studied. Semen was selected by a discontinuous Percoll gradient and incubated during in vitro capacitating conditions with B2 medium supplemented with hFF 20%. Percoll pelleted spermatozoa were incubated in either B2 (B2-Percoll) or B2 supplemented with hFF (hFF-Percoll). In hFF-Percoll, we observed a time-dependent (24 h) decrease in both the cholesterol and phospholipid contents (cholesterol: 10.1 vs. 8.7 nmol 10(-7) spermatozoa; phospholipids: 17.5 vs. 15.7 nmol 10(-7) spermatozoa, P < 0.05). This decrease in cholesterol and phospholipids in human spermatozoa was concomitant with a high straight line velocity, a high progressive motility percentage and an increased value of lateral head displacement without any significant alteration of the spermatozoal membrane. No modification of the cholesterol: phospholipid ratio after 2 and 24 h of incubation in either B2-Percoll (0.61, 0.54) in hFF-Percoll (0.59, 0.63) was observed when compared with original control semen. It is suggested that the decrease in cholesterol and phospholipids in hFF-Percoll may be taken into account for the changes of membrane modification as part of the capacitation process.

Cholesterol↗
PubMedDate not supplied

Ultrastructural comparison of human spermatozoa along a Percoll density gradient.

We studied the possible deleterious effects of Percoll gradient centrifugation processing on spermatozoal integrity in 18 semen samples from patients participating in our IVF program, using optical and electron microscopy. Substantial recovery by sperm count was obtained in the 100% Percoll layer (32%), with greater numbers of motile, alive spermatozoa (P < .01). Whether samples studied were from fertile or infertile men, no significant differences, using nonparametric tests with transmission electron microscopy, appeared in spermatozoal membranes, acrosomes, or nuclei either before or after Percoll treatment. No deleterious effects of Percoll use on spermatozoa were detected during the study.

Cell Membrane↗
PubMedDate not supplied

[Microinjection in France: report of the BLEFCO multicentric study].

In order to evaluate the assisted fertilizations in France, BLEFCO association has analysed 436 and 1,781 attempts for SUZI and ICSI respectively. For SUZI, the transfer rate was 62% and the pregnancy per attempt rate was 10%. For ICSI, whatever indications, the transfer rate was 86% and the pregnancy per attempt rate was 21%. ICSI in cases of altered sperm without previous IVF represented 46% of ICSI attempts. No relationship between the transfer rate and the indication of ICSI has been observed. However, in case of unexplained fertilization failures, the pregnancy per attempt rate is significantly lower when compared to the other indications.

Cytoplasm↗