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Biomedical subjects

D Boucher

Publications and source records attributed to D Boucher.

At least 55 records · Page 3Linked to original sources
PubMed1996

Improvement of motility and fertilization potential of postthaw human sperm using glutamine.

The effectiveness of three amino acids, glutamine, proline, and histidine, and one amino acid-related compound, betaine, in preserving human sperm diluted v/v in a basal medium (BM) containing 14% glycerol during the freeze-thaw (FT) process was studied. At 80 mM in BM, only glutamine improved the 5- to 60-min postthaw total and progressive motilities and velocity. The presence of glutamine at 80 mM is not sufficient to achieve lower concentrations of the toxic agent glycerol in FT medium. Glutamine may therefore have a mechanism of protection on human spermatozoa that is independent from that of glycerol. The zona-free hamster egg penetration test showed that the percentage of eggs penetrated was significantly greater when spermatozoa were frozen-thawed with 80 mM glutamine in BM. Consequently, the presence of glutamine at 80 mM in a glycerol-FT medium maintains human sperm motility and fertilizing ability during the FT process.

Animals↗
PubMed1996

[Microtubules: functional polymorphisms of tubulin and associated proteins (structural and motor MAP's)].

In neuronal cells, microtubules are built from a very large number of alpha- and beta-tubulin variants. This diversity is due to the expression of a multigene family and to a combination of several original posttranslational modifications. Similarly, structural and motor microtubule-associated proteins, which regulate the assembly of microtubules, the modeling of their network and the mediation of their functions, are also very heterogeneous. As a consequence, mixing of these two protein polymorphisms leads to the formation of functionally-distinct microtubules. We have shown that polyglutamylation, the major posttranslational modification of neuronal tubulin, was used as a progressive regulator in the binding of structural and motor microtubule-associated proteins, in modulating gradually the conformation of the tubulin carboxy-terminal domain, playing thus a crucial role in microtubule dynamics.

Animals↗
PubMed1995

Cholesterol, phospholipids and markers of the function of the accessory sex glands in the semen of men with hypercholesterolaemia.

The effect of hypercholesterolaemia on the cholesterol and phospholipid content of spermatozoa and seminal plasma was studied. Testosterone and specific markers of the accessory sex glands were also measured. Semen samples from 11 hypercholesterolaemic patients (plasma cholesterol > 6.42 mmol/l, plasma triglycerides < 2 mmol/l) were compared with those of 11 normocholesterolaemic controls (plasma cholesterol < 5.14 mmol/l, plasma triglycerides < 2 mmol/l). Cholesterol, phospholipids and the molar ratio of cholesterol: phospholipids were not significantly different between the two groups of patients either in spermatozoa or in seminal plasma. In hypercholesterolaemic patients the total amount of carnitine in the ejaculate was significantly higher, but there were no significant differences in the levels of acid phosphatase or fructose. There were no significant differences in seminal plasma levels of testosterone in the two groups of subjects. These results suggest that hypercholesterolaemia has no effect on cholesterol and phospholipid levels in spermatozoa and does not cause gross modification of the secretory function of the accessory sex glands.

Acid Phosphatase↗
PubMed1994

Polyglutamylation of tubulin as a progressive regulator of in vitro interactions between the microtubule-associated protein Tau and tubulin.

The multiple functions of microtubules are mediated by various structural and motor microtubule-associated proteins (MAPs). To harmonize these functions in different places of a single cell, the key problem is to regulate the interactions of these proteins with microtubules. The chemical diversity of tubulin isoforms, which constitute the microtubule wall, could represent a molecular basis for this control. Using an in vitro assay of ligand blotting, we found that the microtubule-associated protein Tau interacts differentially with the diverse posttranslationally-modified isotubulins: its binding is mainly restricted to moderately-modified alpha- and beta-tubulin isoforms. We obtained evidence that the recently-discovered polyglutamylation, which consists of the sequential, posttranslational addition of one to six glutamyl units to both alpha- and beta-tubulin subunits, regulates the binding of Tau as a function of its chain length. The relative affinity of Tau, very low for unmodified tubulin, increases progressively for isotubulins carrying from one to three glutamyl units, reaches an optimal value, and then decreases progressively when the polygutamyl chain lengthens up to six residues. Our results suggest that the unmodified C-terminus of tubulin exerts a constitutive inhibition on Tau binding, probably by locking the MAP-binding site, and that this inhibition could be first released and then restored as the polyglutamyl chain grows. As the posttranslational chain does not appear to interact directly with Tau, it is thought that the growth of this chain from one to six glutamyl units causes a progressive, conformational shift in the structure of the C-terminal domain of tubulin, thus leading to the observed modulation of affinity.

Animals↗
PubMed1994

Characterization of a monoclonal antibody to a human intra-acrosomal antigen that inhibits fertilization.

Among monoclonal antibodies (mAb) selected after the immunization of mice with human ejaculated spermatozoa, mAb I9G9 (IgG1 kappa) was found by immunoperoxidase staining to label most of the acrosome of human spermatozoa permeabilized with methanol-acetone. The antigen was poorly expressed on the surface of fresh ejaculated sperm, but was detectable on most viable sperm after 5-h incubation in medium containing human serum albumin (HSA) followed by 30-min incubation with the calcium ionophore A23187. This treatment resulted in acrosomal loss. Immunoelectron microscopy labeling with I9G9 mAb localized the antigen within the acrosome. Immunocytochemistry on testis sections showed that antigen was located in the round spermatids within the adluminal compartment of the seminiferous epithelium. Western blotting of sperm extract proteins showed that sperm intra-acrosomal (SIAA) recognized by I9G9 mAb had a polymorphism of immunogenic peptides from 16 to 35 kDa. Most of the antigenic peptides possessed an isoelectric point of approximately 5. When spermatozoa were treated with a series of protease inhibitors, the polymorphism of immunogenic peptides was reduced, suggesting that the multiple form of the antigen was due, at least in part, to proteolytic processing. In the testis, only a single peptide band of 35 kDa was detected with mAb I9G9. Studies of human tissue specificity by Western blotting showed that the epitope recognized by I9G9 mAb was present solely in ejaculated spermatozoa and the testis. I9G9 mAb did not agglutinate or immobilize sperm but inhibited the penetration of zona-free hamster ova by human sperm.

Acrosome↗
PubMed1994

Morphologic prognostic factors of malignant mixed müllerian tumors of the ovary: a clinicopathologic study of 15 cases.

Fifteen ovarian malignant mixed müllerian tumors (MMMT) of the ovary are reported in an attempt to identify morphologic factors of prognostic interest. Several features were correlated to survival: histologic subtype and nuclear and histologic grades of the epithelial component; histologic subtype, grade, and mitotic rate of the mesenchymal component; necrosis and epithelial-to-mesenchymal ratio. The epithelial component was mainly of endometrioid (four cases) and serous (four cases) types. The mesenchymal component was largely heterologous, of which five were of chondromatous and five of rhabdomyoblastic differentiation. This latter differentiation was further demonstrated by electron microscopy (two cases) and immunohistochemistry (four cases). Ten tumors showed hyaline droplets that stained for alpha 1-antitrypsin in two cases. Eight patients died of their disease, 13 days to 32 months after diagnosis (median, 5 months). Seven were alive 3 to 49 months (median, 10 months) after initial therapy. No morphologic factor was found to correlate with survival, but a tendency was observed for ovarian MMMTs with a high epithelial nuclear grade, a predominance of the mesenchymal component, or a rhabdomyoblastic mesenchymal component to be associated with more aggressive behavior. The histologic appearance of metastases did not correlate with prognosis.

Aged↗
PubMed1993

gli, a zinc finger transcription factor and oncogene, is expressed during normal mouse development.

The oncogene GLI is amplified and expressed in some cases of human malignant glioma and undifferentiated childhood sarcoma and is the prototype for a gene family characterized by a highly conserved set of five tandem zinc fingers and a consensus cysteine-histidine link. This zinc finger motif has been shown to bind DNA with sequence specificity and may mediate transcriptional regulation. Since GLI is expressed in embryonal carcinoma cell lines but not in most normal adult tissues and shows significant sequence similarity within its zinc finger domain to cubitus interruptus dominant (ciD), a Drosophila segmentation gene known to be important in the morphogenesis of the posterior portion of each larval segment, we established the temporal and tissue expression patterns of the mouse homologue of human GLI in day 10 through 18 mouse embryos with Northern blotting, reverse transcriptase coupled PCR, and in situ hybridization. gli transcripts were demonstrated on days 10 through 18 of mouse embryonic development as well as in normal adult uterus, brain, testis, and limb. Tissue expression of gli during gestation was demonstrated in Meckel's precartilage mesenchyme, the basis occipitus, rib mesenchymal condensations, primordial vertebral bodies, digital mesenchymal condensations in forefoot and hindfoot plates, the ependymal layer of the spinal cord, and the mesoderm of the gastrointestinal tract. Expression persisted throughout gestation in developing bone and cartilage of the extremities, the ribs, and the vertebral bodies, as well as the gastrointestinal tract mesoderm. These findings support a role for gli family genes in normal craniofacial and digital development in mammals first suggested by the demonstration of translocation breakpoints within the GLI3 gene in families with the Greig cephalopolysyndactylyl syndrome and subsequently by reduced gli3 expression in the mouse mutant extra toes. It is surprising that a single gene would be expressed in such a wide range of mesenchymal structures.

Amino Acid Sequence↗
PubMed1993

Assessment of polyploidy in human morulae and blastocysts using co-culture and fluorescent in-situ hybridization.

Fluorescence in-situ hybridization with DNA probes for X, Y and no. 18 chromosomes was used to analyse human morulae (n = 13) and blastocysts (n = 41), obtained after co-culture on Vero cells. On the basis of the number of hybridization signals, the proportion of embryos with more than five polyploid cells was 30.8% for morulae and 29.3% for blastocysts. These values are similar to those for mixoploidy (mosaicism of diploid and polyploid cells) observed in blastocysts of animal species. The results were confirmed by scanning electron microscopy, which showed a wide variation in the size of blastocyst nuclei, and by classical cytogenetic analysis. Mixoploidy seems to be a normal feature in preimplantation embryos and to occur very early in human embryo development. This lays open to doubt the preimplantation diagnosis of genetic errors at these stages, since results obtained from single cell analysis may not be representative of the whole embryo.

Animals↗
PubMed1993

[Expression of IL6 and TNF-alpha in normal and pathological kidney].

The IL6 and TNF alpha specific mRNAs are expressed in normal human kidney; IL6 protein can be detected in normal glomerular mesangium by immunochemistry while TNF alpha is not present. Increased expression of IL6 mRNA is found within the glomeruli in mesangioproliferative glomerulonephritis and IL6 protein is detectable in proliferating mesangial areas. TNF alpha is mainly detected in infiltrating macrophages. During acute rejection episodes de novo expression of TNF alpha appears in renal transplant tubular epithelial cells as well as that of HLA class II antigens, ICAM-1 and VCAM-1 molecules. In renal cell carcinomas, the tumoral cells produce in vivo and in vitro IL6 and TNF alpha at the mRNA and protein levels. Therefore parenchymatous renal cells can produce IL6 and TNF alpha in various pathological conditions. However the mechanisms which regulate the production of these cytokines as well as their role in the genesis or the amplification of tissular damage remain to be elucidated.

Carcinoma, Renal Cell↗
PubMed1992

Insertional mutation of a gene involved in growth regulation of the early mouse embryo.

A transgenic mouse strain derived from embryonic stem (ES) cells infected with multiple copies of a retroviral vector carries a recessive insertional mutation resulting in prenatal lethality. A detailed histological analysis of developing embryos has shown that the mutation results in hyperplasia of both embryonic and extraembryonic ectoderm and failure of mesoderm formation in the egg cylinder stage embryo. The number of cells in each lineage of normal and mutant embryos was estimated using stereological analysis of serial sections taken from implantation sites. We observed a 2-fold increase in the number of embryonic ectoderm cells in mutant embryos at 7.5 days postcoitum (dpc). In addition, we found that mutant embryonic ectoderm cells are only 0.6 times as large as normal cells. The number of extraembryonic ectoderm cells in mutant embryos at 7.5 dpc is also increased, by almost 4-fold. Mutant extraembryonic ectoderm cells are also smaller than normal, being only two-thirds the size of wild-type cells. The mutant phenotype suggests that the gene identified by this insertional mutation plays an important role in the growth control of early embryonic lineages.

Animals↗
PubMed1992

Heterogeneity of Tau proteins during mouse brain development and differentiation of cultured neurons.

Tau microtubule-associated proteins constitute a group of developmentally regulated neuronal proteins. Using the high-resolution two-dimensional polyacrylamide gel electrophoresis system, we have resolved more than 60 distinct Tau isoforms in the adult mouse brain. Tau protein heterogeneity increases drastically during the second week of brain development. In neuronal primary cell cultures, some of these developmental changes can be observed. The increase of Tau heterogeneity in culture is more limited and reaches a plateau after a period corresponding to the second week of development. Most, if not all, of the vast Tau heterogeneity can be attributed to intensive post-translational phosphorylation, which may affect the structure of the proteins.

Animals↗
PubMed1992

Changes in carnitine and acetylcarnitine in human semen during cryopreservation.

L-Carnitine and acetylcarnitine concentrations were determined in spermatozoa and seminal plasma from 15 men, in both fresh ejaculate and frozen-thawed semen with cryoprotective medium. Sperm motility was also evaluated. In fresh samples, the levels of carnitine and acetylcarnitine in seminal plasma were comparable whereas in spermatozoa, acetylcarnitine predominated. Cryopreservation did not change the carnitine and acetylcarnitine levels in seminal plasma nor the carnitine concentration in spermatozoa; by contrast, the acetylcarnitine level in spermatozoa was decreased in 14 cases (110 +/- 8 versus 210 +/- 20 nmol/10(8) cells). This decrease in acetylcarnitine content was greater during semen dilution in cryoprotectant than after the freezing/thawing process. Motility was also decreased in all cases after the freezing/thawing process. These results suggest that acetylcarnitine recovery in spermatozoa is further evidence of the deleterious effect of the cryoprotective medium in the cryopreservation of semen.

Acetylcarnitine↗
PubMed1992

Androgenic activity in 15-day-old male rats: role of the maternal pineal gland.

Female Sprague-Dawley rats, exposed to a long (18L:6D) or a short (6L:18D) photoperiod from 21 days of age, were mated when they reached 55 days of age. On Day 2 of gestation, dams were pinealectomized or sham-operated. Pre- and postnatal photoperiods were identical, and offspring were killed at 15 days of age. Maternal pinealectomy had no effect when rats were kept on 18L:6D. Rats born to sham-operated mothers and kept on 6L:18D had higher testicular testosterone and androstenedione content than offspring raised on the long photoperiod. This stimulatory effect of the short photoperiod was blocked by maternal pinealectomy and was not dependent on the offspring's own pineal since it was observed in both sham-operated and neonatally (on Day 5 after birth) pinealectomized rats. When sham-operated mothers housed on 18L:6D were treated daily during pregnancy and lactation by s.c. melatonin injection, there was an increase in the testicular testosterone content of offspring. It was concluded that when rats are maintained on a 6L:18D cycle the maternal pineal gland enhances the testicular testosterone and androstenedione content in 15-day-old offspring. This effect is probably mediated by maternally derived melatonin. At 15 days of age, the pineal of the offspring had no influence on testicular function.

Androgens↗
PubMed1992

Influence of rat testicular macrophages on Leydig cell function in vitro.

The influence of co-cultures of rat testicular macrophages and Leydig cells (LC) on LC morphology and steroidogenesis was investigated with and without macrophage stimulation by a bacterial lipopolysaccharide (LPS). LC showed an elongated form in the presence of stimulated testicular macrophages. In the presence of non-stimulated testicular macrophages a significant inhibition of testosterone production was observed (decrease of 33%) from 48 h in co-culture while an increase of 16% was obtained at the same culture time, after stimulation of macrophages by LPS. When LC were treated with testicular macrophage-conditioned media (MCM) obtained from LPS-treated macrophages, they became fusiform and there was stimulation (78%) of steroid production. After human FSH stimulation (1-1000 mIU ml-1), MCM from testicular macrophages was no more effective in enhancing testosterone production by LC than was media from untreated LC. Similar experiments with LPS were conducted with macrophages of peritoneal origin. Peritoneal macrophages stimulated or not by LPS in co-cultures with LC or peritoneal MCM did not significantly modify testosterone production. However, these cells were able to modify LC morphology when LPS-MCM was added to LC-culture medium. The present results suggest strongly that testicular macrophage-LC interactions could be important in the control of LC steroidogenesis.

Animals↗
PubMed1992

Androgenic function in adult rats: influence of the pineal gland of the mother and of the offspring.

Female rats exposed to long (LD 18:6) or short (LD 6:18) photoperiods from 21 days of age were mated when they reached 55 days of age. On day 2 of gestation animals of each group were either pinealectomized or sham-operated. Lighting regimens were not changed during the course of the study. Male offspring of the four groups of dams were sacrificed on day 70 after birth. Rats that were maintained on long photoperiod had higher testicular testosterone, androstenedione, and dihydrotestosterone content than those raised on a LD 6:18 cycle. Whatever the breeding photoperiod used, maternal pinealectomy induced no modification of reproductive function. Among rats kept in short photoperiod, neonatal pinealectomy (on day 5 after birth) resulted in an enhanced testicular androgen content without any modification of plasma androgen concentration. These results indicate that (1) the previously reported effect of the mother's pineal on pubertal rat testicular function is not present in adulthood and (2) the pineal of the offspring is required to maintain normal testicular androgen content in the adult rat but exerts no influence on circulating androgens.

Androstenedione↗
PubMed1992

[Influence of the maternal pineal gland on the testicular function in rats].

Female rats were exposed to a short (6L:18D) photoperiod from 21 days of age. On day 2 of gestation, animals were pinealectomized or sham-operated. Lighting regimens were not changed during the course of the study. Male offspring of the 2 groups of rats were sacrificed on days 21 after birth. Pinealectomy of the mother induced the following modifications: a decrease in prostate and seminal vesicle weights, a decrease in testicular testosterone and androstenedione content and in plasma dihydrotestosterone levels. We conclude that when rats are maintained on a 6L:18D cycle the maternal pineal gland stimulates the testicular function in 21-day-old offspring.

Androgens↗