5′-Cytosine DNA-methyltransferase mRNA levels in hereditary colon carcinoma

 DNA methylation plays an important part in the regulation of gene expression. Alterations in DNA methylation in tumours have been reported and have been used to generate hypotheses about mutagenesis and silencing of tumour suppressor genes. However, the underlying mechanism is still poorly understood, and conflicting data on the levels of overexpression of 5′-cytosine DNA methyltransferase in sporadic colon carcinoma have been published. We used a competitive RT-PCR assay for quantification of mRNA of 5′-cytosine DNA methyltransferase in colon biopsies obtained from patients with hereditary colon carcinoma syndromes and compared the results with those obtained in a control group. No significant difference was found between the flat mucosa of FAP patients and the mucosa of the control group. In FAP and HNPCC patients, the 5′-cytosine DNA methyltransferase mRNA levels of adenomas were significantly higher (P<0.05) than of flat mucosa in the same group, but both showed great variability from patient to patient. Our findings suggest that the mRNA levels of methyltransferase cannot be used as predictive marker for screening in families affected by hereditary colon carcinoma. Received: 20 July 1998 / Accepted: 21 September 1998     

Application of a comprehensive subtelomere array in clinical diagnosis of mental retardation

In 2-8% of patients with mental retardation, small copy number changes in the subtelomeric region are thought to be the underlying cause. As detection of these genomic rearrangements is labour intensive using FISH, we constructed and validated a high-density BAC/PAC array covering the first 5 Mb of all subtelomeric regions and applied it in our routine screening of patients with idiopathic mental retardation for submicroscopic telomeric rearrangements. The present study shows the efficiency of this comprehensive subtelomere array in detecting terminal deletions and duplications but also small interstitial subtelomeric rearrangements, starting from small amounts of DNA. With our array, the size of the affected segments, at least those smaller than 5 Mb, can be determined simultaneously in the same experiment. In the first 100 patient samples analysed in our diagnostic practice by the use of this comprehensive telomere array, we found three patients with deletions in 3p, 10q and 15q, respectively, four patients with duplications in 9p, 12p, 21q and Xp, respectively, and one patient with a del 6q/dup 16q. The patients with del 3p and 10q and dup 12p had interstitial rearrangements that would have been missed with techniques using one probe per subtelomeric region chosen close to the telomere.     

Characterization of FcepsilonRI-bearing CD123 blood dendritic cell antigen-2 plasmacytoid dendritic cells in atopic dermatitis

BACKGROUND: The high-affinity receptor for IgE (FcepsilonRI) on myeloid dendritic cells has been shown to play a major role in atopic dermatitis (AD). Plasmacytoid dendritic cells (pDCs), which are instrumental in the defense of viral infections, are present in reduced amounts in the skin of patients with AD, which is characterized by a high susceptibility to viral infections. OBJECTIVE: We explored phenotypical and functional characteristics of pDC in the peripheral blood of patients with AD and healthy individuals. METHODS: Blood dendritic cell antigen-2+CD123+ pDCs were enriched from the peripheral blood of patients with AD and studied in functional assays. RESULTS: Skin-homing molecules such as cutaneous lymphocyte antigen and L-selectin CD62L were expressed in lower levels on pDCs of patients with AD. pDCs expressed high amounts of IgE-occupied FcepsilonRI. Further, FcepsilonRI aggregation on pDCs impaired the surface expression of MHC I and II, induced the production of IL-10, and enhanced the apoptosis of pDCs. Importantly, FcepsilonRI preactivated pDC produced less IFN-alpha and IFN-beta after stimulation with CpG motifs and enhanced the outcome of immune responses of the TH2 type. CONCLUSION: From these data, we conclude that FcepsilonRI-bearing pDCs from patients with AD (1) are different from pDCs of healthy individuals, (2) might be important in the pathophysiology of AD, and (3) contribute to the enhanced susceptibility of patients with AD to viral infections.     

Structure and stability of poly(vinyl chloride), 4. Unsaturated ketones and their role in the initiation of thermal degradation

The thermal dehydrochlorination of poly(vinyl chloride) (PVC) in an inert atmosphere was investigated by the continuous potentiometric method. The effect of the structure of alicyclic and aliphatic α,β-unsaturated ketones on the rate of dehydrochlorination was examined, and a new mechanism of initiation for the dehydrochlorination of PVC was suggested. The results obtained demonstrate that the basic cause of the thermal instability of PVC are structures of the type of cisoid α,β-unsaturated ketone, dienone, or polyenone which by the dehydrochlorination of regular structural PVC units form isolated double bonds which, in turn, initiate the chain dehydrochlorination of PVC by allyl activation.     

Epitope analysis with monoclonal antibodies directed against class II molecules subdivides HLA-DR2, DR3 and DR4: correlations with cellularly defined Dw specificities

Monoclonal antibodies (Mabs) defining 14 distinct polymorphic epitopes have been produced against the class II antigens of HLA-DR3Dw3DQw2 cells. Population analysis indicates that Mab C1 is directed against the DQw2 specificity and Mab M6 against the DRw52 specificity. The remaining Mabs define epitopes shared by the class II molecules of DR3 and various other specificities. Seven DR3Dw3DQw2 haplotypes were examined and could be divided into two types based on the presence of the epitope defined by Mab M3. Analysis of DR2 and DR4 homozygous cells with these Mabs revealed several distinct patterns of epitope expression. These subdivisions were found to correlate with the cellularly defined Dw specificities.     

The repair of DNA damage induced in human peripheral lymphocytes with styrene oxide

Isolated human peripheral lymphocytes were treated in vitro with styrene-7, 8-oxide (SO) and the kinetics of the repair of induced DNA damage was assessed by comet assay during further incubation of lymphocytes. Using a modified assay we measured simultaneously the number of single strand breaks in DNA (SSBs) and the sites sensitive to endonuclease III (endo III) that most probably represent abasic sites in DNA molecules. SO induced DNA damage in a dose-dependent manner and both SSBs and endo III sites were removed from the DNA by a repair process with a half time about 2-4 hours. The damage was repaired completely within 12 hours after the treatment.     

Combined liquid-crystalline polymers with chiral phases, 2. Lateral substituents

Chiral combined liquid-crystalline polymers (i. e. polymers with the mesogenic groups in the main chain as well as in the side groups) with dipole moments perpendicular to the mesogenic groups were synthesized and characterized. These dipole moments were introduced by lateral substituents, which were located at different parts of the mesogen or directly at the chiral centre. The polymers, thus prepared, show crystalline or glassy phases at room temperature and smectic A, chiral smectic C^* or cholesteric phases at higher temperatures. Since the lateral substituents decrease the melting temperature more strongly than the clearing temperature, the liquid-crystalline phases are broadened compared to the unsubstituted polymers. Often glassy liquid-crystalline phases are obtained. The dipole moments perpendicular to the mesogenic groups or at the chiral centre may help to obtain a high spontaneous polarisation in the chiral smectic C^* phase (ferroelectricity).     

Liquid crystalline elastomers based on liquid crystalline side group,main chain and combined polymers

Covalently crosslinked liquid crystalline networks with elastic properties were prepared in isotropic solution from linear liquid crystalline polymers. As linear precursors for the networks were used: (i) polymers with the mesogenic groups in the side groups (polyacrylates and polymethacrylates), (ii) polymers with the mesogenic groups in the main chain (polymalonates) and (iii) polymers with the mesogenic groups in main chain and side groups (“combined liquid crystalline polymers”). In all crosslinked polymers the liquid crystalline phases of the linear polymers are retained. For low degrees of crosslinking (≤2 mol-%) the phase transition temperatures remain nearly unchanged. These elastomers are very soft above T_g and can be easily stretched for more than 100%. For higher degrees of crosslinking the phase transition temperatures are reduced.     

Transition from a botanical to a molecular classification in tree pollen allergy: implications for diagnosis and therapy

Tree pollens are among the most important allergen sources. Allergic cross-reactivity to pollens of trees from various plant orders has so far been classified according to botanical relationships. In this context, cross-reactivities to pollens of trees of the Fagales order (birch, alder, hazel, hornbeam, oak, chestnut), fruits and vegetables, between pollens of the Scrophulariales (olive, ash, plantain, privet, lilac) and pollens of the Coniferales (cedar, cypress, pine) are well established. The application of molecular biology methods for allergen characterization has revealed the molecular nature of many important tree pollen allergens. We review the spectrum of tree pollen allergens and propose a classification of tree pollen and related allergies based on major allergen molecules instead of botanical relationships among the allergenic sources. This molecular classification suggests the major birch pollen allergen, Bet v 1 as a marker for Fagales pollen and related plant food allergies, the major olive pollen allergen, Ole e 1, as a possible marker for Scrophulariales pollen allergy and the cedar allergens, Cry j 1 and Cry j 2, as potential markers for allergy to Coniferales pollens. We exemplify for Fagales pollen allergy and Bet v 1 that major marker allergens are diagnostic tools to determine the disease-eliciting allergen source. Information obtained by diagnostic testing with marker allergens will be important for the appropriate selection of patients for allergen-specific forms of therapy.