PubMed Health⌕ Search

Biomedical subjects

J C Czyba

Publications and source records attributed to J C Czyba.

At least 19 recordsLinked to original sources
PubMed2001

Apoptosis in preimplantation mammalian embryo and genetics.

The presence of dead cells in the preimplantation mammalian embryo has been well described. Since Kerr et al. (1972), it has become apparent that these cells die by apoptosis, a form of programmed cell death. This review analyses the recent morphological and biochemical evidence that apoptosis play a role in early mammalian embryo development. Normal and apoptotic (i.e. fragmented) embryos express several apoptosis-related genes during mammalian preimplantation embryo development, with severe changes when apoptosis is activated; these findings support a model in which mammalian preimplantation embryo development is regulated by the ratio of pro- and -anti- apoptotic genes. Apoptosis may be a normal feature in human preimplantation development, even in vivo, and may play an active role in the developing embryo through the removal of genetically abnormal cells. Contrary to these beneficial effects, apoptosis may have detrimental effects if either the number of apoptotic cells or ratio of these cells to the normal cells is elevated. According to this value, embryos could either continue to develop or arrest.

Animals↗
PubMed2000

Cyclodextrin enhances spermicidal effects of magainin-2-amide.

Magainins are antimicrobial peptides with known spermicidal activity. Their activity is inhibited by cholesterol present in eukaryotic cell membranes. Pretreatment of spermatozoa with methyl-beta-cyclodextrin, which extracts cholesterol from cell membranes and induces capacitation, sensitizes them to magainin-2-amide as shown by a decrease in human sperm motility determined by computer-assisted sperm analysis and a concomitant decrease in sperm viability, as measured by MitoTracker(R) Red CMXRos labeling. Magainin-2-amide affects mainly the fast progressive spermatozoa inducing them directly into an immotile state, without an increase in motile non-progressive and slow progressive spermatozoa. We conclude that methyl-beta-cyclodextrin highly potentiates the deleterious effect of magainin-2-amide on human spermatozoa. Most probably, this effect can be explained by cholesterol extraction from sperm cell membranes.

Animals↗
PubMed2000

A randomized prospective study comparing pregnancy rates after clomiphene citrate and human menopausal gonadotropin before intrauterine insemination.

OBJECTIVE: To determine whether hMG offers an advantage over clomiphene citrate (CC) in achieving pregnancy after IUI with husband's sperm. DESIGN: Randomized prospective trial. SETTING: Infertility patients in a university teaching hospital. PATIENT(S): Fifty-eight women under 39 years old undergoing ovulation induction before IUI. INTERVENTION(S): The women were assigned randomly to one of two treatment groups. Patients in group I (CCHH) received CC for the first two cycles and hMG for the last two cycles. Patients in group II (HHCC) received hMG for the first two cycles and CC for the last two cycles. MAIN OUTCOME MEASURE(S): Cycle fecundity rates for the two treatment modalities were compared statistically with use of life-table analysis. RESULT(S): Of the 174 cycles studied, overall cycle fecundity rate was 11.11 (9 of 81 cycles) in the CCHH group and 10.75 (10 of 93 cycles) in the HHCC group. The difference was not statistically significant. The cycle fecundity rate was 14.44% (13 of 90 cycles) for cycles with CC and 7.14% (6 of 84) with hMG. The difference was not statistically significant. CONCLUSION(S): These data suggest that CC is an effective alternative to hMG in the population examined.

Abortion, Spontaneous↗
PubMed2000

Proteasomes in human spermatozoa.

In the present study we describe the localization of proteasomes in human spermatozoa by means of immunolabelling with different monoclonal and polyclonal antibodies detected by confocal microscopy. Western blotting confirmed the specificity of the antibodies and has shown that proteasomes are present in spermatozoa and in seminal fluid. In spermatozoa proteasomes are concentrated in the neck region where the centrioles are located. Some labelling was also detected at the periphery of the head, but no proteasomal antigens were detected in either the nucleus or associated with the flagellum. Proteasome inhibitors did not affect the motility of the spermatozoa, acrosome reaction nor zona binding. It is hypothesized that paternal proteasomes enter the oocyte during fertilization in tight association with the centrioles and may serve a special function during further development which can be associated with the function of a hypothetical proteolysis centre.

Blotting, Western↗
PubMed2000

Localization of proteasomes in human oocytes and preimplantation embryos.

In the present study we describe the localization of proteasomes in human oocytes, apoptotic preimplantation embryos, and triploid preimplantation embryos by means of immunolabelling with the MCP21 monoclonal antibody detected by confocal microscopy. While in the oocytes proteasomes are scattered throughout the cytoplasm, in the pronuclear zygote they appear to concentrate at the periphery of the cytoplasm and do not enter the pronuclei. During early cleavage stages, proteasome immunolabelling is concentrated in the nuclei, while the examination of triploid blastocysts showed that proteasomes had a similar cellular distribution to somatic cell lines, i.e. in the nuclei but not in the nucleoli or the cytoplasm. It appears that the distribution of proteasomes dramatically changes during human preimplantation embryo development.

Cysteine Endopeptidases↗
PubMed1999

The mean of sperm parameters in semen donations from the same donor. An important prognostic factor in insemination.

We analysed 12,100 consecutive cycles of artificial insemination by donor spermatozoa in 1901 infertile couples. In our analysis, particular attention was given to finding an appropriate way of taking into account the respective effects of female and male factors on the pregnancy success rate and the level at which these factors act (cycle vs. woman and donation vs. donor). A total of 1213 pregnancies occurred. The pregnancy rate per cycle was lower as the age of the woman increased (p < 0.0001) and varied with the type of infertility: fecundity was higher (p = 0.03) in the case of azoospermia than of severe oligozoospermia. After taking into account these factors, significant unexplained variation in likelihood to conceive remained. A part of this heterogeneity was shown to be due to variation in fecundability between semen donors. In order to explain this heterogeneity between donors, compositional covariates were used, particularly the mean of results of the semen analysis performed for donations from the same donor. For each semen characteristic, the overall mean of the different donations of a donor was an important predictive factor of successful insemination: after taking into account all of the other factors, the odds ratios for an increase of 50 x 10(6)/mL spermatozoa, of a 20% increase in sperm motility and of a 2 point increase in the post-thaw quality index, were, respectively, 1.13, 1.37 and 1.56. After adjustment for these factors, the specific characteristics of each semen donation were no longer significantly predictive of successful insemination. This observation has a biological interpretation: sperm with low parameters but produced by a normally fertile man can have a satisfactory success rate.

Adult↗
PubMed1995

Six year follow-up of cryopreserved human embryos.

In 1987, we became aware of the importance of remaining in contact with couples whose embryos had been cryopreserved for > 1 year. As a result, a questionnaire was designed to follow the fate of these embryos. Of 407 couples with cryopreserved embryos, 262 couples opted to use them within 1 year with the intention of fulfilling a parental plan. The remaining 145 couples were questioned by six successive questionnaires sent out between 1987 and 1992. By the end of the study, 336 of the 407 couples (82.5%) had chosen to utilize their embryos in a parental plan. In most cases, the maximum delay of response (5 years according to the Council of State) was respected. The remaining 71 couples (17.5%) either abandoned the parental plan or had not given any information by the end of the study. Initially, anonymous donation to another couple was chosen in preference to destroying the surplus embryos (32 versus 18 couples, P < 0.05). Latterly, however, these differences have balanced out (24 versus 28, not significant). Only those couples who initially opted to donate embryos to another couple changed their attitude in later years. In the long run, 62 couples decided not to pursue their parental plan; of these, 24 couples chose to make a gift to another couple, 28 couples opted for destruction, and 10 chose to make a gift to research. Nine couples (out of 71) declined to make a decision, but they had all achieved a pregnancy during an in-vitro fertilization (IVF) attempt. Three of these were lost to follow-up, i.e. 0.7% of all couples benefiting from the freezing technique.

Cryopreservation↗
PubMed1995

Cumulative conception rate following intrauterine artificial insemination with husband's spermatozoa: influence of husband's age.

This paper presents the analysis of 901 cycles of intrauterine artificial insemination with the husband's spermatozoa (AIHIU) in 274 couples who obtained 80 pregnancies. The cumulative pregnancy rate after three cycles of AIHIU was 22% and reached 39% after six cycles. Univariate analysis disclosed two factors of poor prognosis: duration of infertility > 3 years (P = 0.01) and husband's age (P = 0.03). Multivariate analysis revealed that the most significant factor contributing to a decreased likelihood of pregnancy was the age of the husband (P = 0.01), then duration of infertility and dysovulation. The wife's age > or = 35 years did not appear to be of poor prognostic value when taking into consideration the three other factors.

Adult↗
PubMed1995

Morphological and cytogenetic observations of unfertilized human oocytes and abnormal embryos obtained after ovarian stimulation with pure follicle stimulating hormone following pituitary desensitization.

Morphological and cytological observations of 189 unfertilized oocytes and 40 abnormal embryos obtained from 32 patients in a routine in-vitro fertilization programme were performed. Both the oocytes and the embryos were mounted whole to preserve the original topology of all the structural elements. With the applied protocol of ovarian stimulation associating pituitary desensitization and follicle stimulating hormone stimulation, a high degree of immaturity of the unfertilized eggs was observed in comparison with previous reports. This immaturity was deduced from the higher incidence of unfertilized eggs arrested at the germinal vesicle or metaphase I stage, as well as metaphase II oocytes with multiple metaphase plates. Nine triploid and four tetraploid embryos were analysed: except for one tetraploid embryo, all the polyploid embryos cleaved. The percentages of mononucleated blastomeres in these polyploid embryos were 57 and 27% respectively. We also analysed 21 cleaving diploid embryos which exhibited a high degree of fragmentation. No more than 40% of the blastomeres contained a single nucleus. Moreover, in only one of the 21 diploid embryos could all the blastomeres be considered normal.

Blastomeres↗
PubMed1993

[Psychological approach of the infertile male].

Male infertility is usually anxiogenic, and it is often responsible for sexual dysfunctions due to the cultural indissociability of the virility and fertility concepts on the one hand, and to the timing of sexual intercourse in the ovulation period on the other hand. The intrusion of medicine in the life of the infertile couple frequently amplifies the existing psychological problems and discloses other problems by questioning the representation systems of identity, procreation and filiation.

Humans↗
PubMed1993

[Study of different components in spermatic function after failure of in vitro fertilization].

The fertilizing potential of sperm depends on numerous properties which influence its functional competence. In order to understand the causes of IVF failure, we studied some of these properties-movement characteristics, hyperactivated motility, acrosome reaction-for infertile sperm (0% in vitro fertilization) and compared to those of fertile sperm (> or = 50% fertilization, control group). Movement characteristics, assessed by video-micrographic analysis, are significantly different for the 2 groups: infertile sperm register the lowest values for motility characteristics and hyperactivation. The addition of ionophore A23187 to the medium improves the hyperactivation and the acrosome reaction, the values for the latter, however, remain significantly lower compared to the control. These results are in favor of a detailed study of motility and induced acrosome reaction as complement for the diagnosis of male infertility.

Acrosome↗
PubMed1992

Spontaneous and ionophore induced acrosome reaction in asthenozoospermic infertile semen.

Spontaneous and ionophore-induced ability of spermatozoa to acrosome-react was examined in asthenozoospermic infertile patients and fertile donors. Spermatozoa were washed free of seminal plasma and capacitated in B2 medium for 2 h at 37 degrees C. Subsequently 5, 10, 20 and 30 microM A23187 (final concentrations) were added to equal aliquots of these samples and incubated for an additional 30 min. The acrosome reaction was then determined by the triple stain technique. The percentage of spontaneous reaction (no ionophore) in asthenozoospermic samples was similar to that in fertile samples (4.2 and 3.8, respectively). However, the ionophore-induced reaction rate remained significantly lower in asthenozoospermic samples than in normozoospermic samples.

Acrosome↗
PubMed1991

Hyperactivated motility of sperm from fertile donors and asthenozoospermic patients before and after treatment with ionophore.

Hyperactivated motility of capacitated sperm was studied before and after contact for 30 min with the Ca2+ ionophore A23187. Sperm from fertile donors and asthenozoospermic infertile patients were incubated in the presence of increasing concentrations of A23187 in the medium. At 5-10 microM, the ionophore induced a significant increase (P less than 0.05) in the percentage of hyperactivation of sperm from asthenozoospermic subjects. Higher concentrations (20 and 30 microM) were needed to enhance hyperactivation of sperm in the fertile population. In the latter, extended contact with the ionophore induced no significant change compared to a 30-min incubation period. Since this type of movement is an essential feature of the fertilizing gamete, a low hyperactivation rate may partly explain fertilization failure in the asthenozoospermic group.

Calcimycin↗
PubMed1991

[The value of the level of alpha-1,4-glucosidase and seminal l-carnitine in patients with oligoasthenospermia].

Samples of sperm have been obtained from 95 who consulted us for infertility. In each case seminal plasma was examined for levels of alpha-1,4-glucosidase and L-carnitine. Our results have led us to fix the threshold value of 42.6 mlU per ejaculate for alpha-1,4-glucosidase and 960 nanomoles of L-carnitine below those levels that we thought occur where the origin of the oligospermia is obstructive (series 1 patients). In series 2 patients the cause of the oligospermia purely being secretory, there is normal epididymal function and therefore the excretory doubts are proven. It is not impossible to have both pathologies because we have found this in men of the intermediate groups C and D. We have found that there is a correlation between the presence of epididymal pathology and a drop in epididymal markers which can be found in severe oligospermia (which can be epididymal in origin and not testicular). Also when there is non abnormalities in the spermogram. This last situation can occur in "invisible" abnormalities of spermaturation in the epidymus.

Biomarkers↗
PubMed1990

Improvement of human early embryo development in vitro by coculture on monolayers of Vero cells.

Human "spare" embryos, judged unsuitable for freezing because of their poor quality, were cocultured for 5 days on a "Vero" cell layer. These epithelial cells were selected because kidney and genital tract have a common embryologic origin and "Vero" cells are a safe and highly controlled cellular support used for vaccine production. In the control group, the embryos were cultured in culture medium alone (B2 + 15% serum). At the end of the culture, the number of blastocysts was significantly higher in the coculture group: 61% vs. 3%. Moreover, at least half of the blastocysts were expanding and hatching (13/25), with a chronologically normal development. These observations suggest that (1) the coculture system improves human embryonic development; (2) it can rescue early degenerating embryos; (3) beneficial effects of coculture are not strictly genital-tract specific, but rather epithelium dependent. This coculture system could be used for in vitro fertilization to prolong in vitro culture and thus make it possible to transfer embryos at a more appropriate time, to eliminate early-blocked eggs, and to freeze embryos at the blastocyst stage, when freezing procedures are most successful.

Animals↗