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A Zini

Publications and source records attributed to A Zini.

44 records · Page 3Linked to original sources
PubMed1996

POU-domain gene expression during spermatogenesis.

Spermatogenesis is an orderly process whereby male germ cells pass through sequential phases of differentiation to develop into mature spermatozoa. At present, little is known about the factors that regulate this process. The POU domain represents a group of transcription-activator proteins with well-described roles in development. These proteins have been shown to regulate the tissue-specific expression of genes involved in cellular differentiation. The recent identification of Sperm-1, a testis-specific POU-domain protein expressed in primary spermatocytes just prior to the onset of meiosis, suggests that this protein may be involved in the regulation of male germ-cell differentiation. Continued evaluation of Sperm-1 and other related transcriptional activators may shed some light on the regulation of spermatogenesis.

Animals↗
PubMed1996

Immunohistochemical localization of endothelial nitric oxide synthase in human testis, epididymis, and vas deferens suggests a possible role for nitric oxide in spermatogenesis, sperm maturation, and programmed cell death.

Recent work has implicated nitric oxide (NO) in several aspects of male genital physiology including erectile function and androgen secretion, as well as in vitro effects on sperm motility and capacitation. The objectives of this study were to characterize the distribution of endothelial nitric oxide synthase (eNOS) in "normal" human testis, epididymis, and vas deferens and in testis pathology. Nitric oxide synthase protein was localized immunohistochemically using an eNOS monoclonal antibody. Endothelial NOS protein co-localized to areas that showed positive NADPH diaphorase activity. Within the testis, eNOS protein was localized to the cytoplasm of Leydig cells and Sertoli cells at all stages of spermatogenesis. Within the epididymis and vas deferens, eNOS was localized to the epithelium. Endothelial NOS was also localized to endothelial cells in all tissues; it was not detectable in normal germ cells. Endothelial NOS and diaphorase activity were, however, detected in degenerating or apoptotic intraepithelial germ cells. In addition, prematurely shed spermatocytes and spermatids had intense eNOS expression. Previous studies have suggested a role for NOS in the contractile, hemodynamic, and hormonal aspects of testicular function as well as in epididymal secretion. The studies reported herein suggest a role for eNOS in spermatogenesis and germ cell degeneration.

Antibody Specificity↗
PubMed1993

Reactive oxygen species in semen of infertile patients: levels of superoxide dismutase- and catalase-like activities in seminal plasma and spermatozoa.

Reactive oxygen species (ROS) can be detected in the semen of 40% of infertile men, whereas none is detected in semen from normal men. The ROS detected in semen are a reflection of the imbalance between ROS production and degradation. The aim of the present study was to determine whether a lowered scavenging capacity or an increased production of ROS was responsible for the ROS detected in semen samples from infertile men. Two activities were investigated: (1) catalase-like activity, which is responsible for the degradation of H2O2 and (2) superoxide dismutase-like (SOD-like) activity which is responsible for the degradation of .O2-. Catalase-like and SOD-like activities were found in whole seminal plasma, in dialyzed seminal plasma (> 12 kD), in an ultrafiltrate of seminal plasma (< 5 kD) and in spermatozoa. There was no significant difference in the SOD-like activities measured in spermatozoa, or in seminal plasma (whole or fractionated) from samples that did or did not produce ROS. SOD-like activity originated mostly from the high molecular weight components of seminal plasma. However, the catalase-like activity of whole seminal plasma and of spermatozoa was significantly greater (P = 0.01) in those samples that produced ROS as compared to those that did not. The catalase-like activity in dialyzed seminal plasma, and an ultrafiltrate of seminal plasma from semen samples that did or did not produce ROS were not statistically different. The catalase-like activity of the seminal plasma originated equally from high and low molecular weight components.(ABSTRACT TRUNCATED AT 250 WORDS)

Catalase↗
PubMedDate not supplied

Loss of left testicular volume in men with clinical left varicocele: correlation with grade of varicocele.

It is reported that a clinical left varicocele is associated with loss of ipsilateral testicular volume. We have examined the loss of left testicular volume in infertile men with clinical left varicocele using ultrasound-derived measurements of testicular volume. We have reviewed the testicular volumes, maximum internal spermatic vein diameters, and the clinical reports of 404 men presenting for infertility evaluation at our institution between 1992 and 1996. Men with bilateral or subclinical varicoceles were excluded from the study. Subclinical varicoceles were diagnosed by the ultrasonographic demonstration of one or more veins having a maximal diameter of more than 3 mm. In men with clinical left varicocele, mean left testicular volume was less than right testicular volume (12.7 vs. 13.8 mL, P < .001). This finding was not observed in men without varicocele (12.3 vs. 12.6 mL, P > .05). In men with left varicocele, the difference between right and left testicular volume (right minus left) increased with increasing varicocele grade. Our data demonstrate that a left varicocele is associated with loss of left testicular volume. The results also show that the degree of left testicular hypotrophy is proportional to the clinical grade of the varicocele.

Humans↗
PubMedDate not supplied

Germ cell apoptosis and endothelial nitric oxide synthase (eNOS) expression following ischemia-reperfusion injury to testis.

There is evidence to suggest that reactive oxygen species (ROS) are involved in ischemia-reperfusion injury to the testis. Nitric oxide (NO), a ubiquitous free radical produced by the nitric oxide synthases (NOS), has been implicated in physiologic and pathologic interactions with ROS. We examined the effect of testicular ischemia on germ cell apoptosis and endothelial NOS (eNOS) expression. Adult rats were subjected to unilateral 720 degrees testicular torsion for 1 or 3 hours and 24 hours later, testes were harvested for immunohistochemical studies. Apoptosis was detected by in situ 3' end-labeling of DNA with digoxigenin-ddUTP and eNOS protein was detected using an eNOS monoclonal antibody. Tests subjected to 3 hours of torsion had a threefold increase in apoptotic germ cells per cross-sectional area compared to sham testes (P < .05). In addition to its known expression in Leydig, Sertoli, and vascular endothelial cells, eNOS was detected in the cytoplasm of degenerating germ cells. Consecutive testis sections stained for eNOS and cellular DNA fragmentation demonstrated co-localization of eNOS protein and germ cell apoptosis. The detection of strong immunostaining in apoptotic germ cells supports a role of eNOS in germ cell degeneration after testicular ischemia-reperfusion and suggests that NO is associated with germ cell apoptosis.

Animals↗
PubMedDate not supplied

Low levels of nitric oxide promote human sperm capacitation in vitro.

The influence of nitric oxide on human sperm hyperactivation and capacitation, as well as its mechanism of action and its possible origin from spermatozoa were studied. Percoll-washed spermatozoa from healthy volunteers were incubated in Ham's F-10 medium supplemented or not with the nitric oxide-releasing agents, diethylamine-NONOate or spermine-NONOate, in combination or not with superoxide dismutase or catalase (scavengers for the superoxide anion and for hydrogen peroxide, respectively), or with sodium nitrate, sodium nitrite, or preincubated NONOates. Sperm hyperactivation, capacitation, and nitric oxide synthase activity were determined. High concentrations (0.3 to 1 mM) of NONOates reduced sperm motility. However, a lower concentration (0.1 mM) of the two NONOates had no effect on the percentage of sperm motility or of hyperactivation but resulted in a significant increase in sperm capacitation (24% +/- 4%) when compared to that of control spermatozoa (Ham's F-10 alone, 12% +/- 2%). Nitric oxide released by the NONOates appeared responsible for this effect because sodium nitrate or nitrite or preincubated NONOates (to exhaust the formation of nitric oxide) had no influence on sperm capacitation. Catalase, but not superoxide dismutase, abolished the capacitating action of the NONOates. No nitric oxide synthase activity was detected in spermatozoa, whether they were in their basal state or already capacitated. Furthermore, the nitric oxide synthetase inhibitor L-NG nitroarginine methyl ester did not block sperm capacitation induced by fetal cord serum ultrafiltrate. It is therefore concluded that, although spermatozoa do not possess detectable nitric oxide synthase activity, low levels of nitric oxide induce human sperm capacitation, and this action likely involves hydrogen peroxide.

Acrosome↗
PubMedDate not supplied

Catalase mRNA expression in the male rat reproductive tract.

Reactive oxygen species (ROS) have been shown to impair sperm function. The actions of ROS are reduced by antioxidant enzymes, including catalase. Although catalase-like activity has been demonstrated in semen, there has been no localization or characterization of catalase mRNA expression in the male reproductive tract. Catalase mRNA levels were evaluated by northern blot analysis and in situ hybridization from the male reproductive organs of normal 60-day-old rats, testes of 10- to 90-day-old rats, and testes of rats subjected to efferent duct ligation. Radioactive DNA probes were synthesized using a Klenow polymerase-based specific primer synthetic procedure with a known published sequence for rat catalase. All tissues demonstrated a single transcript of 2.5 kilobases (kb). Low levels of catalase mRNA were detected in the normal testis, epididymis, vas deferens, and prostate. No expression was detectable with northern analysis in seminal vesicle. The levels of catalase mRNA in reproductive organs were compared with the high levels of expression detectable in rat liver. In the testis, catalase expression was primarily localized to peritubular and interstitial cells. In the epididymis and prostate, mRNA was detected in the epithelium. The observed decrease in catalase mRNA levels in the maturing rat testis is consistent with its interstitial localization. The increase in testicular catalase mRNA levels seen in parallel with progressive thinning of the germinal epithelium after efferent duct ligation is also in keeping with a peritubular or interstitial cell localization. The relatively low levels of catalase mRNA expression in the normal adult male reproductive tract undermine the role of catalase as a major antioxidant enzyme in these tissues. The low levels of catalase mRNA in the testis, and the undetectable levels in the seminiferous epithelium, however, imply that the germinal epithelium is predisposed to an oxidative state. These findings may help to explain the known susceptibility of the testis to oxidative stress.

Animals↗