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Biomedical subjects

C Weemaes

Publications and source records attributed to C Weemaes.

15 recordsLinked to original sources
PubMed2003

[From gene to disease; ataxia telangiectasia].

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterised by cerebellar ataxia, telangiectasia, immune defects, and a predisposition to malignancy. Chromosomal breakage is a feature. AT cells are abnormally sensitive to cell kill by ionising radiation and abnormally resistant to inhibition of DNA synthesis by ionising radiation. The responsible gene, 'ataxia telangiectasia mutated' (ATM) plays a crucial role in a signal transduction pathway, regulating the cell cycle, and in preventing damaged DNA from being reproduced. This rare genetic disorder manifests itself during childhood. The illness is progressive and most individuals die in their second or third decade of life due to infections or cancer. AT is difficult to diagnose due to its rarity and clinical heterogeneity. Both a physical examination and several laboratory tests are necessary for establishing its proper diagnosis.

Antibody Formation↗
PubMed2003

Development of immunoglobulin A in infancy and childhood.

Serum and salivary concentrations of immunoglobulin A1 (IgA1) and IgA2 were studied in 105 Icelandic children aged 0-12 years. Serum concentrations of both IgA1 and IgA2 increased slightly (P < 0.001) during childhood. The salivary IgA1/IgA2 ratio tended to decrease during the same period; this trend is less apparent when omitting the youngest children. The salivary IgA1 and IgA2 output could be high, even in children with low levels of serum IgA. Only polymeric IgA was found in whole saliva. Interestingly, in serum, most IgA1 and IgA2 were polymeric during infancy. The proportion of polymeric IgA decreased, when the concentration of IgA increased. The polymeric form of IgA might provide the infant with better protection against invading microorganisms by activation of the innate immune mechanisms.

Age Factors↗
PubMed2000

Genetic variation in ICF syndrome: evidence for genetic heterogeneity.

ICF syndrome is a rare autosomal recessive immunoglobulin deficiency, sometimes combined with defective cellular immunity. Other features that are frequently observed in ICF syndrome patients include facial dysmorphism, developmental delay, and recurrent infections. The most diagnostic feature of ICF syndrome is the branching of chromosomes 1, 9, and 16 due to pericentromeric instability. Positional candidate cloning recently discovered the de novo DNA methyltransferase 3B (DNMT3B) as the responsible gene by identifying seven different mutations in nine ICF patients. DNMT3B specifically methylates repeat sequences adjacent to the centromeres of chromosome 1, 9, and 16. Our panel of 14 ICF patients was subjected to mutation analysis in the DNMT3B gene. Mutations in DNMT3B were discovered in only nine of our 14 ICF patients. Moreover, two ICF patients from consanguineous families who did not show autozygosity (i.e. homozygosity by descent) for the DNMT3B locus did not reveal DNMT3B mutations, suggesting genetic heterogeneity for this disease. Mutation analysis revealed 11 different mutations, including seven novel ones: eight different missense mutations, two different nonsense mutations, and a splice-site mutation leading to the insertion of three aa's. The missense mutations occurred in or near the catalytic domain of DNMT3B protein, indicating a possible interference with the normal functioning of the enzyme. However, none of the ICF patients was homozygous for a nonsense allele, suggesting that absence of this enzyme is not compatible with life. Compound heterozygosity for a missense and a nonsense mutation did not seem to correlate with a more severe phenotype.

Abnormalities, Multiple↗
PubMed1999

Kinetic study of the irreversible thermal and pressure inactivation of myrosinase from broccoli (Brassica oleracea L. Cv. italica).

Thermal and pressure inactivation of myrosinase from broccoli was kinetically investigated. Thermal inactivation proceeded in the temperature range 30-60 degrees C. These results indicate that myrosinase is rather thermolabile, as compared to other food quality related enzymes such as polyphenol oxidase, lipoxygenase, pectinmethylesterase, and peroxidase. In addition, a consecutive step model was shown to be efficient in modeling the inactivation curves. Two possible inactivation mechanisms corresponding to the consecutive step model were postulated. Pressure inactivation at 20 degrees C occurred at pressures between 200 and 450 MPa. In addition to its thermal sensitivity, the enzyme likewise is rather pressure sensitive as compared to the above-mentioned food quality related enzymes. By analogy with thermal inactivation, a consecutive step model could adequately describe pressure inactivation curves. At 35 degrees C, pressure inactivation was studied in the range between 0. 1 and 450 MPa. Application of low pressure (<350 MPa) resulted in retardation of thermal inactivation, indicating an antagonistic or protective effect of low pressure.

Brassica↗
PubMed1998

Radiation induction of p53 in cells from Nijmegen breakage syndrome is defective but not similar to ataxia-telangiectasia.

p53-mediated signal transduction after exposure to ionizing radiation was examined in cells from patients with Nijmegen breakage syndrome (NBS), an autosomal recessive disease characterized by microcephaly, immunodeficiency, predisposition to malignancy, and a high sensitivity to ionizing radiation. NBS cells accumulated p53 protein in a dose-dependent fashion, with a peak level 2 hrs after irradiation with 5 Gy. However, the maximal level of p53 protein in NBS cells was constantly lower than in normal cells. Moreover, this attenuation of p53 induction was confirmed by decreased levels of p21WAF1 protein, which is transcriptionally regulated by p53 protein. This defective induction of p53 protein in NBS is similar to that in ataxia-telangiectasia (AT), although the induced levels of p53 protein in NBS appeared to be the intermediate between normal cells and AT cells. This moderate p53 induction in NBS cells is consistent with the relatively mild radiation sensitivity and the abnormal cell cycle regulation post-irradiation, as present in NBS. Furthermore, all NBS cell lines used here exhibited time courses of p53 induction similar to normal cells, which is in contrast with p53 induction in AT cells, where the maximum induction shows a delay of approximately 2 hrs compared with normal cells. These evidences suggest a different function of each gene product in an upstream p53 response to radiation-induced DNA damage.

Ataxia Telangiectasia↗
PubMed1997

Genetic mapping using microcell-mediated chromosome transfer suggests a locus for Nijmegen breakage syndrome at chromosome 8q21-24.

Nijmegen breakage syndrome (NBS) is an autosomal recessive disorder characterized by microcephaly, short stature, immunodeficiency, and a high incidence of cancer. Cultured cells from NBS show chromosome instability, an increased sensitivity to radiation-induced cell killing, and an abnormal cell-cycle regulation after irradiation. Hitherto, patients with NBS have been divided into the two complementation groups V1 and V2, on the basis of restoration of radioresistant DNA synthesis, suggesting that each group arises from a different gene. However, the presence of genetic heterogeneity in NBS has been considered to be controversial. To localize the NBS gene, we have performed functional complementation assays using somatic cell fusion between NBS-V1 and NBS-V2 cells, on the basis of hyper-radiosensitivity, and then have performed a genomewide search for the NBS locus, using microcell-mediated chromosome transfer followed by complementation assays based on radiosensitivity. We found that radiation resistance was not restored in the fused NBS-V1 and NBS-V2 cells and that only human chromosome 8 complements the sensitivity to ionizing radiation, in NBS cell lines. In complementation assays performed after the transfer of a reduced chromosome, merely the long arm of chromosome 8 was sufficient for restoring the defect. Our results strongly suggest that NBS is a homogeneous disorder and that the gene for NBS is located at 8q21-24.

Abnormalities, Multiple↗
PubMed1996

Nijmegen breakage syndrome.

Nijmegen breakage syndrome (NBS), a rare autosomal recessive condition also known as ataxia telangiectasia (AT) variants V1 and V2, is characterised by microcephaly, typical facies, short stature, immunodeficiency, and chromosomal instability. We report the clinical, immunological, chromosomal, and cell biological findings in 42 patients who are included in the NBS Registry in Nijmegen. The immunological, chromosomal, and cell biological findings resemble those in AT, but the clinical findings are quite different. NBS appears to be a separate entity not allelic with AT.

Abnormalities, Multiple↗
PubMed1996

Potential Bacillus subtilis alpha-amylase-based time-temperature integrators to evaluate pasteurization processes.

Thermal inactivation kinetics of Bacillus subtilis alpha-amylase (BSA) in different environmental conditions was studied by performing isothermal experiments. As a response property, residual enzymic activity and residual heat of enzyme deterioration were chosen. A comparison of processing values determined from the read-out of a system with actual integrated processing values revealed the potentials of these systems as time-temperature integrators to be used in the pasteurization domain (temperatures of 70 to 100 degrees C) for target attributes with z-values ranging from 6 to 12 degrees C.

Bacillus subtilis↗
PubMed1991

Cartilage hair hypoplasia, metaphyseal chondrodysplasia type McKusick: description of seven patients and review of the literature.

We describe 7 cases of cartilage hair hypoplasia (CHH) with emphasis on the clinical and immunological aspects. The literature on CHH is reviewed and symptoms in 63 non-Amish cases are summarized. In this autosomal recessive disorder the immunodeficiency, hair abnormalities, and severity of skeletal involvement show extremely variable expressivity, between and within families. Two of the 3 sib-pairs among our cases demonstrate the great difference in expression within one family. At adult age roentgenological abnormalities can be very mild, or even absent. An impairment in cell-mediated immunity is present in all of our cases and seems a consistent manifestation in CHH; however, sometimes it is very subtle and without clinical symptoms.

Abnormalities, Multiple↗
PubMed1981

Normal microbicidal function of monocytes in a girl with chronic granulomatous disease.

The history of a 13-year-old girl with a syndrome resembling Chronic Granulomatous Disease (C.G.D.) is described. Metabolic studies in granulocytes and monocytes classified the patient as having C.G.D. The granulocytes failed to kill Staphylococcus aureus and Candida Albicans; however, the killing of these microorganisms by the patient's monocytes was nearly normal. Family studies revealed no abnormalities in the phagocytic cells of the parents and the siblings.

Adolescent↗