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Biomedical subjects

M Vekemans

Publications and source records attributed to M Vekemans.

At least 163 records · Page 9Linked to original sources
PubMed1992

Molecular characterization of a mouse Y chromosomal repetitive sequence that detects transcripts in the testis.

145SC5 is a Y chromosomal repetitive sequence isolated from a BALB/c mouse and is unique in that it detects poly(A)-containing transcripts in the testis. We determined nucleotide sequences of 145SC5 and a related cDNA clone designated PC11 and compared their sequences to that of pYMT2/B, another related cDNA clone. 145SC5 and PC11 are almost identical (97%), while PC11 and pYMT2/B share 84% identity. In situ hybridization and Southern blot analysis with XXSxr male mice demonstrated that 145SC5-related sequences were distributed over the entire length of the Y chromosome including the short arm. Two types of Y chromosome are present in inbred mouse strains: the Mus musculus musculus type and M.m. domesticus type. Among 26 inbred strains surveyed, 145SC5 detected polymorphims only in the M.m. domesticus Y chromosome.

Amino Acid Sequence↗
PubMed1992

Segregation analysis reveals tight genetic linkage between the spontaneously arising neural tube defect gene splotch (Sp) and Pax-3 in an intraspecific mouse backcross.

Concurrent research has recently characterized Sp2H, a radiation induced mutation at the splotch (Sp) locus, and found alterations in the murine paired box gene, Pax-3, in homozygous Sp2H DNA. It was proposed that Sp and Pax-3 are the same gene. This report presents additional genetic evidence in support of this finding through linkage studies. Southern blot analysis of genomic DNAs from a panel of 125 intraspecific [(Sp/+ x CBA/J)F1-Sp x CBA/J] backcross mice reveals no crossover between Pax-3 and the spontaneously occurring splotch allele, Sp. This positions Pax-3 within 2.9 cM of the Sp locus (95% confidence interval) and suggests tight genetic linkage between the two marker genes.

Animals↗
PubMed1992

[Contraception using a subcutaneous implant, Norplant].

The contraceptive device Norplant, not yet commercialized in Belgium, has been studied prospectively on 198 women, which were followed for up to 42 months per patient. All together, 2,643 months of use were surveyed. Norplant consists of 6 silastic capsules, liberating levonorgestrel, a synthetic progestagen. The pregnancy protection lasts for 5 years. Insertion site is the inner part of the upper arm. The Pearl Index was 0.46% women-years (only one pregnancy occurred); the continuity rate was high (86% after 1 year and 60% after 2 years). The main side effects were menstrual disturbances and abnormal intermenstrual blood loss. No other important side effects have been found. There is no absolute contra-indication to the use of Norplant.

Adolescent↗
PubMed1991

Splotch (Sp2H), a mutation affecting development of the mouse neural tube, shows a deletion within the paired homeodomain of Pax-3.

The molecular basis of the mouse mutation splotch (Sp), which is associated with spina bifida and exencephaly, was analyzed at three of its alleles, Sp, Sp2H, and Spr. We mapped the paired box gene Pax-3 within the Inha to Akp3 interval, near or at the Sp locus on chromosome 1, and found Pax-3 to be deleted in heterozygous Spr/+ mice. Analysis of genomic DNA and cDNA clones constructed from Sp2H/Sp2H embryos identified a deletion of 32 nucleotides in the Pax-3 mRNA transcript and gene. This deletion maps within the paired homeodomain of PAX-3 and is predicted to create a truncated protein as a result of a newly created termination codon at the deletion breakpoint. Our study provides evidence for a causal link between deletion of the paired homeodomain of Pax-3 and the Sp2H mutation, and infers that Pax-3 plays a key role in normal neural development.

Amino Acid Sequence↗
PubMed1991

Interstitial tandem direct duplication of the long arm of chromosome 4 (q23-q27) and possible assignment of the structural gene encoding human aspartylglucosaminidase to this segment.

We report on a girl with a previously undescribed de novo direct tandem duplication 4q involving the segment q23----q27. Clinical manifestations included postnatal growth and psychomotor retardation, microcephaly, hirsute forehead, epicanthic folds, strabismus, depressed nasal bridge, long philtrum, small mouth, tetralogy of Fallot, and sacral dimple. Her phenotype is compared with that of previously reported cases of duplication 4q. An increased activity of the enzyme aspartylglucosaminidase (AGA) in cultured fibroblasts was demonstrated. This suggests possible assignment of the AGA gene to the chromosomal segment 4q23----4q27.

Aspartylglucosylaminase↗
PubMed1991

Outgrowth of stable class I major histocompatibility complex-expressing subsets from immunogenic variants of a murine mammary carcinoma: association with a differentially staining region on chromosome 9.

We have examined interactions among intratumor subpopulations during the rejection of immunogenic variants of a murine mammary carcinoma (SPI) and in the outgrowth of tumorigenic "revertant" subsets. Analysis of subclones isolated during the early phase of rejection of one immunogenic variant revealed extensive cellular heterogeneity of tumor-forming ability and class I major histocompatibility complex (MHC) expression. Two main categories of subclones were identified. One set expressed high levels of class I MHC (MHCH) and grew poorly or not at all in normal syngeneic mice. The second set of clones expressed generally low levels of class I MHC (MHCL) and exhibited progressive growth in vivo, similar to the parent tumor. The steady-state mRNA levels for class I MHC and beta 2-microglobulin were constitutively elevated in MHCH clones compared to MHCL clones or the parent tumor. However, in vivo tumorigenic outgrowths from immunogenic variants always expressed the MHCH phenotype. A cytogenetic analysis was carried out to determine the clonal origin and lineage relationship of in vivo selected tumor outgrowths. Surprisingly, tumor outgrowths from mixtures of karyotypically distinct MHCH and MHCL subclones were derived from one lineage within the MHCH subset, despite the fact that MHCH subclones exhibited slower growth in vivo than MHCL subsets when analyzed individually. These results suggest that in polyclonal populations the various subsets sometimes interact in a way that overrides the influence of immunogenic and MHC phenotypes of individual subclones.

Adenocarcinoma↗
PubMed1991

The host resistance locus Bcg is tightly linked to a group of cytoskeleton-associated protein genes that include villin and desmin.

In the mouse, innate resistance or susceptibility to infection with a group of unrelated intracellular parasites which includes, Mycobacteria, Salmonella, and Leishmania is determined by the expression of a single dominant autosomal gene designated Bcg located on the proximal portion of chromosome 1. The gene is expressed at the level of the mature tissue macrophage and influences its capacity to restrict intracellular proliferation of the parasites. We have used restriction fragment length polymorphism analysis in segregating populations of inter- and intraspecific backcross mice and in recombinant inbred strains to position four new marker genes, transition protein 1 (Tp-1), desmin (Des), the alpha subunit of inhibin (Inha), and retinal S-antigen (Sag), in the vicinity of the host resistance locus, Bcg. The gene order for Tp-1, Des, Inha, and Sag was established in an eight-point testcross with respect to anchor loci previously assigned to that portion of mouse chromosome 1 and was found to be centromere-Fn-1-Tp-1-(Vil,Bcg)-Des-Inha-Akp-3-Acrg+ ++-Sag. Two of these new marker genes were found very tightly linked to Bcg: Des was located 0.3 +/- 0.3 cM distal from (Vil,Bcg) and 0.3 +/- 0.3 cM proximal to Inha. Tp-1 mapped 0.8 +/- 0.8 cM proximal and Sag 12.8 +/- 1.7 cM distal to (Vil,Bcg). Tp-1, Des, Inha, and Sag all fall within a large mouse chromosome 1 segment homologous with the telomeric region of the long arm of human chromosome 2 (2q). Our findings indicate that the two closest markers to the host resistance locus, Bcg, encode cytoskeleton-associated proteins which are capable of interaction with actin filaments.

Animals↗
PubMed1991

Molecular characterization of a deletion encompassing the splotch mutation on mouse chromosome 1.

We have used a set of markers newly assigned to the proximal portion of mouse chromosome 1 to characterize the chromosomal segment deleted in the splotch-retarded (Spr) mouse mutant. Among nine markers tested in the heterozygote Spr/+mouse, we have identified four genes, Vil, Des, Inha, and Akp-3, which map within the Spr deletion. The closest distal marker to the deletion is the Acrg gene, with the distal deletion breakpoint mapping within the 0.8-cM segment separating Akp-3 and Acrg. The most proximal gene to the Spr deletion is Tp1. The proximal deletion breakpoint maps within the 0.8-cM segment separating Tp1 and Vil. The minimum size of the Spr deletion would therefore be limited to 14 cM, the genetic distance between Vil and Akp-3. The maximum size of the Spr deletion is estimated to be 16 cM, the genetic distance between Tp1 and Acrg.

Animals↗
PubMed1990

Distal deletion of chromosome 1q in an adult.

An adult patient with mongoloid appearance, profound retardation and autistic-like behavior was found to have a deletion of the distal bands of chromosome 1q. To our knowledge, this is the oldest patient with distal deletion 1q.

Adult↗
PubMed1990

Ring chromosome 4 in a child with duodenal atresia.

We report on a 19-month-old girl with ring chromosome 4 and a multiple congenital anomaly syndrome. The clinical and cytogenetic findings are compared with those of previous cases in whom the breakpoints in ring chromosome 4 are known.

Abnormalities, Multiple↗
PubMed1990

Clonal lines of aneuploid cells in Rothmund-Thomson syndrome.

We report on a 21-month-old white boy with the Rothmund-Thomson syndrome. The karyotype on fibroblasts from an area of skin with poikiloderma showed the 46,XY,17 + der(17),t(2;17)(q11;p13) pattern. Karyotype on fibroblasts from normal skin showed two different abnormal patterns: 47,XY, + 8 and 47,XY, + i(2q). His lymphocytes had a normal 46,XY pattern. These findings indicate in vitro abnormalities. They are explained by a degree of chromosomal instability.

Aneuploidy↗
PubMed1990

Malformations and minor anomalies in children whose mothers had prenatal diagnosis: comparison between CVS and amniocentesis.

The frequency of abortion following chorionic villus sampling (CVS) is similar to that following amniocentesis. However, there is no information on long-term effects, such as malformations in liveborn children exposed to CVS. We evaluated 189 infants whose mothers had either CVS or amniocentesis as participants in the Canadian Collaborative Randomized Trial, a prospective assessment of the safety of CVS compared with amniocentesis. The participation rate of children who could be contacted was 95%. Ninety-five of the 189 infants (50.2%) had been exposed to CVS, 87 (46%) to amniocentesis, and 7 (3.8%) to both. (The latter group was excluded from calculations.) One hundred twenty-eight (128) children had greater than or equal to one minor anomalies but no major abnormalities: 58 of 95 (60%) in the CVS and 70 of 87 (80%) in the amniocentesis group. Twenty-six children had malformations: 17 (17.8%) in the CVS and 9 (10.3%) in the amniocentesis group. Only one anomaly, Sturge-Weber dysplasia (amniocentesis group), was potentially severe and none were life-threatening. Superficial cavernous hemangiomas (strawberry nevi) were noted more frequently in children in the CVS group (12.6%) than in the amniocentesis group (3.4%), but only slightly higher than in the general public. We conclude that exposure to CVS is not associated with an increased frequency of malformations or minor anomalies in infants compared with amniocentesis although we observed a higher frequency of superficial cavernous (strawberry) hemangiomas in the children in the CVS group.

Amniocentesis↗
PubMed1990

Aminopterin-like syndrome sine aminopterin associated with translocation involving chromosomes 5 and 10.

We studied a baby born with physical features suggestive of the aminopterin syndrome, but without exposure of the mother to aminopterin during pregnancy. G-banded chromosomes from peripheral blood lymphocytes had a normal 46,XX pattern. However, in 50 skin fibroblasts there was a normal female karyotype in 5 cells and 45 cells showed an apparently balanced reciprocal translocation involving the long arm of chromosome 5 (band q35) and the long arm of chromosome 10 (band q22). The relation of this mosaicism to the abnormal phenotype is unclear.

Abnormalities, Multiple↗
PubMed1990

Duplication of the long arm of chromosome 13 secondary to a recombination in a maternal intrachromosomal insertion (shift).

A rare chromosomal aberration consisting of a chromosomal shift was found in a woman who had prenatal diagnosis because she had previously had a malformed girl with phenotypic features compatible with the diagnosis of Patau syndrome. Chromosome analysis using G, C, and NOR banding showed a direct intrachromosomal insertion of bands 13q12 to 13q14 onto the short arm of chromosome 13 at band 13p13. We discuss this observation and compare it with other published reports of chromosomal shifts.

Adult↗
PubMed1990

Genetic control of the survival of murine trisomy 16 fetuses.

A mouse model that allows for the experimental induction of an aneuploid state has been employed to investigate the factors that control the survival of trisomy 16 fetuses. The prevalence of trisomy 16 fetuses on day 15 of gestation was shown to vary significantly with the genetic background of the female parent. The ability to spontaneously abort a trisomy 16 conceptus was shown to be higher in the mouse strain with a low prevalence of trisomy 16, compared to those mouse strains with a high prevalence of trisomy 16. Furthermore, the maternal ability that selects against, or promotes the survival of a trisomic conceptus was shown to be specific for the trisomy in question.

Abortion, Spontaneous↗
PubMed1990

[AIDS: is it an indication for artificial insemination with anonymous donor sperm?].

Such demands raise difficulties, as the physician has to consider (and has to be the defender of) the coming child. A thorough psychological investigation must be conducted, as the couple's motives and those of each partner considered separately are not necessarily in agreement. Most important for the couple are the persistence of common projects and the strengthening of the bonds. The husband wants to survive through a child, to give an ultimate present and to increase the chance of keeping his partner. The wife shows her faithfulness and diminishes her partner's guilt feelings. She is, anyway, in a difficult situation if trying not to become pregnant, especially if she had already expressed a wish for maternity in normal circumstances. Unconscious mechanisms can intervene, such as fantasmatic adultery (through IAD) which reequilibrates the couple: the husband who brought the HIV has to be forgiven, or punished. Also, and most importantly, one has to analyze the prospects for the child, who is at risk of loosing his father, and also his mother: a later transmission of the virus to her cannot be excluded. The child will be confronted by illness and death of his father, and by heavy family secrets. The attitude of the medical team remains problematic: no clearcut attitude prevails.

Acquired Immunodeficiency Syndrome↗