Skills (8)
Other
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Scientific MembershipsVFS (Vereniging voor fertiliteits studies)
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Journal RefereesMolecular Human Reproduction
Publications (53) View all
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Article: Evaluation of radiographic and genetic aspects of hereditary subluxation of the radial head in Bouviers des Flandres.
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ABSTRACT: To study radiographic and genetic aspects of hereditary radial head subluxation in Bouviers des Flandres. 26 related Bouviers des Flandres affected with bilateral subluxation of the radial head, 10 unaffected related dogs, and 29 unrelated Bouviers des Flandres with diagnoses of nonskeletal diseases. All dogs were radiographically studied, and their DNA was analyzed with a genome-wide screen of 1,536 single nucleotide polymorphisms. In addition, karyotyping was performed in an unaffected dam and its affected offspring. Both forelimbs of affected dogs were disproportionately short with caudolateral subluxation or luxation of the radial head. Angulation of the radial axis at the mid-diaphysis ranged from 9.3 degrees to 30.3 degrees (mean +/- SD, 14.9 +/- 6.1 degrees ), with an estimated age of onset from 0 to 4 months. Poorly defined medial coronoid processes and osteoarthritis of the elbow joint, cranial bowing of the olecranon, and disturbed growth in length of the ulna with sharply demarcated spurs were noticed on radiographs of affected dogs. Genealogical analysis indicated that most affected dogs were closely related, but the mode of inheritance was not clear. The DNA analysis found that 205 single nucleotide polymorphisms were monomorphic in the affected dogs. Conventional chromosome staining revealed no numerical chromosomal aberration. Congenital radial head luxation and subluxation in the studied Bouviers des Flandres were characterized by angulation of the radial axis leading to caudolateral subluxation of the radial head and insufficient growth of the distal portion of the ulna together with cranial bowing of the olecranon.American Journal of Veterinary Research 08/2010; 71(8):884-90. · 1.27 Impact Factor -
Article: Disorders of sexual development and associated changes in the pituitary-gonadal axis in dogs.
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ABSTRACT: Normal sexual differentiation depends on completion of chromosomal sex determination, gonadal differentiation, and development of the phenotypic sex. An irregularity in any of these three steps can lead to a disorder in sexual development (DSD). We examined nine dogs with DSD by abdominal ultrasonography, laparotomy, histologic examination of the gonads, and reproductive tract, cytogenetic analysis, and mRNA expression of the SRY gene. We also determined the plasma concentrations of luteinizing hormone (LH), estradiol-17β, and testosterone before and after administration of gonadotropin-releasing hormone (GnRH) and compared these results with those obtained in anestrous bitches and male control dogs. The gonads of three dogs with DSD contained both testicular and ovarian tissue, while in the other six only testicular tissue was found. Each of the dogs had a uterus. Based on gynecologic examination, cytogenetic analysis, and the histology of the gonads, seven of the nine dogs appeared to be XX sex reversals. Three of these were XX true hermaphrodites and four were XX males; the other two dogs had incomplete XY gonadal dysgenesis. All seven XX sex-reversed dogs were found to be negative for the SRY gene by polymerase chain reaction. The basal plasma luteinizing hormone (LH) concentration was significantly higher in dogs with DSD than in anestrous bitches but not significantly different from that in male dogs. The basal plasma LH concentration increased significantly after GnRH administration in all dogs with DSD. The basal plasma estradiol concentration was significantly higher in dogs with DSD than in anestrous bitches but not significantly different from that in male dogs. The basal plasma testosterone concentration was lower in dogs with DSD than in male dogs. In all dogs with DSD both the basal and GnRH-induced plasma testosterone concentrations were above the upper limit of their respective ranges in the anestrous bitches. In conclusion, the secretion of LH and estradiol in these dogs with DSD, all of which had testicular tissue in their gonads, was similar to that in male control dogs. These results indicate that the basal and/or GnRH-stimulated plasma testosterone concentration might be used to detect the presence of testicular tissue in dogs with DSD.Theriogenology 10/2012; 78(7):1618-26. · 1.96 Impact Factor -
Article: Identification of genes targeted by FSH and oocytes in porcine granulosa cells.
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ABSTRACT: In the mammalian ovarian follicle maturing oocytes are nurtured and supported by surrounding somatic cells, the mural granulosa cells and the cumulus cells. These cells are regulated by follicle-stimulating hormone (FSH), originating from the pituitary, and paracrine factors derived from the oocyte. To gain insight into the mechanisms involved in the regulation of granulosa cell function, this study aimed to identify genes in mural granulosa cells that are regulated by FSH and oocyte secreted factors using the pig as a model organism. Mural granulosa cells were collected from 3-6 mm follicles from sow ovaries and cultured in serum free medium in the presence or absence of FSH and/or isolated cumulus oocyte complexes (COCs). FSH significantly increased both the metabolic activity and progesterone production of granulosa cells, while the presence of COCs reversed these FSH effects. Expression levels of mRNA in the absence/presence of FSH and COCs were analyzed on porcine specific microarrays representing 11,300 genes. Both previously identified and novel FSH target genes as well as some oocyte affected genes were found. Expression of inhibitor of DNA binding protein 2 and 3, ID2 and ID3, was decreased by FSH but increased by COCs, as validated by quantitative PCR. These proteins function as dominant negative basic helix loop helix (bHLH) transcription factors and since all regulated genes contain the consensus E-box sequence that can bind bHLH factors, our data suggest that FSH and COCs may regulate granulosa cell function by tuning the activity of bHLH factors, through ID2 and ID3.Theriogenology 10/2010; 75(2):362-76. · 1.96 Impact Factor -
Article: Exposure of oocytes to the Fusarium toxins zearalenone and deoxynivalenol causes aneuploidy and abnormal embryo development in pigs.
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ABSTRACT: Fungi of the Fusarium species can infect food and feed commodities and produce the mycotoxins zearalenone (ZEA) and deoxynivalenol (DON). Since both toxins have been reported to reduce fertility, the mechanisms of ZEA and DON on inhibition of oocyte maturation were examined. Pig oocytes were matured in the presence of ZEA (a mycotoxin with estrogenlike activity), 17beta-estradiol, and DON (all 3.12 micromol/L). Zearalenone, 17beta-estradiol, and DON inhibited oocyte maturation and caused approximately 34% of the oocytes to form an aberrant spindle. Different ratios of ZEA:DON did not lead to a more severe inhibition of oocyte maturation. Both mycotoxins caused abnormal formation of the meiotic spindle. The developmental competence of oocytes matured in the presence of mycotoxins was further investigated after in vitro fertilization. Presence of ZEA (3.12 micromol/L) during maturation reduced the percentages of oocytes that cleaved and formed a blastocyst to about 12%, compared with 25% of control oocytes. Maturation in the presence of equimolar concentrations of DON was not compatible with development. The ploidy of blastomeres from blastocysts derived from mycotoxin-exposed oocytes was analyzed with fluorescent in situ hybridization. All blastocysts, even those from the control group, contained at least one blastomere with abnormal ploidy, but the variation in the percentages of aneuploid blastomeres was significantly larger in embryos from oocytes exposed to mycotoxins. It is concluded that ZEA and DON can lead to abnormal spindle formation, leading to less fertile oocytes and embryos with abnormal ploidy, and that the effects of ZEA and DON are not synergistic.Biology of Reproduction 12/2007; 77(5):840-7. · 4.01 Impact Factor -
Article: Characterization of the canine desmin (DES) gene and evaluation as a candidate gene for dilated cardiomyopathy in the Dobermann.
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ABSTRACT: Canine-dilated cardiomyopathy (DCM) in dogs is a disease of the myocardium associated with dilatation and impaired contraction of the ventricles and is suspected to have a genetic cause. A missense mutation in the desmin gene (DES) causes DCM in a human family. Human DCM closely resembles the canine disease. In the present study, we evaluated whether DES gene mutations are responsible for DCM in Dobermann dogs. We have isolated bacterial artificial chromosome clones (BACs) containing the canine DES gene and determined the chromosomal location by fluorescence in situ hybridization (FISH). Using data deposited in the NCBI trace archive and GenBank, the canine DES gene DNA sequence was assembled and seven single nucleotide polymorphisms (SNPs) were identified. From the canine DES gene BAC clones, a polymorphic microsatellite marker was isolated. The microsatellite marker and four informative desmin SNPs were typed in a Dobermann family with frequent DCM occurrence, but the disease phenotype did not associate with a desmin haplotype. We concluded that mutations in the DES gene do not play a role in Dobermann DCM. Availability of the microsatellite marker, SNPs and DNA sequence reported in this study enable fast evaluation of the DES gene as a DCM candidate gene in other dog breeds with DCM occurrence.Gene 11/2004; 340(2):241-9. · 2.34 Impact Factor
