István Raskó

Elevated levels of oxidative DNA damage in lymphocytes from patients with Alzheimer's disease

Previous studies have provided evidence of the involvement of oxidative damage in the pathogenesis of Alzheimers disease (AD). Although the role of oxidative stress in the aetiology of the disease is still not clear, the detection of an increased damage status in the cells of patients could have important therapeutic implications. The level of oxidative damage and repair capacity in peripheral lymphocytes of AD patients and of age-matched controls was determined by the Comet assay applied to freshly isolated blood samples with oxidative lesion-specific DNA repair endonucleases. This is less prone to errors arising from oxidative artifacts than chemical analytical methods; and is therefore a relatively reliable, as well as rapid method for assay of oxidative DNA damage in cells. Statistically significant elevations (P < 0.05) of oxidized purines were observed in nuclear DNA of peripheral lymphocytes from AD patients, compared to age matched control subjects, both at basal level and after oxidative stress induced by H(2)O(2.) AD patients also showed a diminished repair of H(2)O(2) -induced oxidized purines.

Caffeine enhancement of X-ray killing in cultured human and rodent cells

A 16 to 20 hr postirradiation incubation with caffeine enhances x-ray killing of rodent and human cells. Cells tested were Chinese hamster ovary (CHO-K1), lung (CHL), V79, mouse L, HeLa S3, human fibroblasts (AF288, TC171, FS9, CRL1166), and a human-hamster hybrid. The effect of caffeine on the x-ray survival curve of these cells was to remove the initial shoulder without significantly altering the mean lethal dose (D/sub 0/). This action can be achieved at caffeine concentrations which of themselves cause less than 15% killing. In randomly growing CHO-K1 cells the caffeine-sensitive process occurs with a half-time of 2 to 5 hr after irradiation. These experiments indicate the existence in human and rodent cells of caffeine-inhibited genome repair for x-ray damage.

Formin Proteins of the DAAM Subfamily Play a Role during Axon Growth

The regulation of growth cone actin dynamics is a critical aspect of axonal growth control. Among the proteins that are directly involved in the regulation of actin dynamics, actin nucleation factors play a pivotal role by promoting the formation of novel actin filaments. However, the essential nucleation factors in developing neurons have so far not been clearly identified. Here, we show expression data, and use true loss-of-function analysis and targeted expression of activated constructs to demonstrate that the Drosophila formin DAAM plays a critical role in axonal morphogenesis. In agreement with this finding, we show that dDAAM is required for filopodia formation at axonal growth cones. Our genetic interaction, immunoprecipitation and protein localization studies argue that dDAAM acts in concert with Rac GTPases, Profilin and Enabled during axonal growth regulation. We also show that mouse Daam1 rescues the CNS defects observed in dDAAM mutant flies to a high degree, and vice versa, that Drosophila DAAM induces the formation of neurite-like protrusions when expressed in mouse P19 cells, strongly suggesting that the function of DAAM in developing neurons has been conserved during evolution.

Apolipoprotein E polymorphism in Pick's disease and in Huntington's disease

The polymorphism of apolipoprotein E (apoE) has been recognized as a genetic risk factor in different neurodegenerative disorders, with or without tau protein- related neuropathology, but few published epidemiological data are available as concerns the association of different apoE alleles with two relatively rare forms of dementia, Picks disease (PiD) and Huntingtons disease (HD). In this study the frequency of the apoE4 allele was examined in 36 persons with histopathologically proven PiD and compared with that of the apoE genotype in 28 HD probands and 79 aged healthy controls. The E4 allele was overrepresented selectively in PiD (42%) as compared with the control population (7%). No such association was found for HD probands (9%). This finding lends further support to the hypothesis that the E4 genotype is not an Alzheimers disease specific susceptibility factor, and that it could be present in diverse dementing disorders with tau protein related neuropathology, such as PiD.

Association study of BMP4, IL6, Leptin, MMP3, and MTNR1B gene promoter polymorphisms and adolescent idiopathic scoliosis.

Study Design. A genetic association study was performed on 126 patients with adolescent idiopathic scoliosis and 197 healthy controls from independent Hungarian pedigrees. Objective. To reveal implication of promoter polymorphisms of bone morphogenetic protein 4 (BMP4), interleukin-6 (IL6), leptin, matrix metalloproteinase-3 (MMP3), melatonin 1B receptor (MTNR1B) genes in adolescent idiopathic scoliosis (AIS). Combinatorial association of these candidate genes was also studied to detect additive effect of certain single-nucleotide polymorphism (SNP) patterns. Summary of Background Data. It was previously unraveled that IL6, MMP3, and MTNR1B genes could be considered as predisposition genes of AIS. Since BMP4 and leptin play a central role in bone formation and remodeling and are in direct interaction with melatonin, IL6, and MMP3, these also can be potential predisposition genes. Methods. The genotyping was determined by polymerase chain reaction-restriction fragment length polymorphism. Results. At a single gene level, no significant differences were found for allele and genotype frequencies of the polymorphisms of these genes between cases or controls; therefore, the formerly detected association of IL6, MMP3, and MTNR1B with AIS was not confirmed in the Hungarian population by independent SNP analysis. However, significantly increased AIS risk was observed at particular combinations of genotypes of paired SNPs of the candidate genes. Conclusions. The genetic effect of promoter polymorphisms of BMP4, IL6, leptin, MMP3, and MTNR1B can be synergistic for susceptibility to AIS. The combinatorial effect can modulate the final biological impact of many susceptibility polymorphisms; therefore, this should be considered at the comparison of results from case-control studies of different populations.

Prevalence of adult-type hypolactasia as diagnosed with genetic and lactose hydrogen breath tests in Hungarians

The prevalence of adult-type hypolactasia varies ethnically and geographically among populations. A C/T–13910 single nucleotide polymorphism (SNP), upstream of the lactase gene, is known to be associated with lactase non-persistence. The aim of this study was to determine the prevalence of lactase-persistent and non-persistent genotypes in the Hungarian population, the age at onset and the applicability of the lactose H2 breath test in comparison with genetic screening. The prevalence of the C/C−13910 genotype among adults was 37%. Hypolactasia starts to appear at around 5 years of age. Over the age of 12 years, almost all of those with a C/C−13910 genotype have lactase non-persistence. The C/C−13910 genotype was closely associated with a positive lactose H2 breath test in symptomatic children, whereas the lactase-persistent genotypes correlated better with a negative H2 test in a control group. In conclusion, supplementary non-invasive breath and genotyping tests furnish a perfect clinical diagnosis.

Y-chromosome analysis of ancient Hungarian and two modern Hungarian-speaking populations from the Carpathian Basin

The Hungarian population belongs linguistically to the Finno‐Ugric branch of the Uralic family. The Tat C allele is an interesting marker in the Finno‐Ugric context, distributed in all the Finno‐Ugric‐speaking populations, except for Hungarians. This question arises whether the ancestral Hungarians, who settled in the Carpathian Basin, harbored this polymorphism or not. 100 men from modern Hungary, 97 Szeklers (a Hungarian‐speaking population from Transylvania), and 4 archaeologically Hungarian bone samples from the 10th century were studied for this polymorphism. Among the modern individuals, only one Szekler carries the Tat C allele, whereas out of the four skeletal remains, two possess the allele. The latter finding, even allowing for the low sample number, appears to indicate a Siberian lineage of the invading Hungarians, which later has largely disappeared.

Comparison of lactase persistence polymorphism in ancient and present‐day Hungarian populations

The prevalence of adult-type hypolactasia varies ethnically and geographically among populations. A C/T-13910 single nucleotide polymorphism (SNP) upstream of the lactase gene is known to be associated with lactase non-persistence in Europeans. The aim of this study was to determine the prevalence of lactase persistent and non-persistent genotypes in current Hungarian-speaking populations and in ancient bone samples of classical conquerors and commoners from the 10th-11th centuries from the Carpathian basin; 181 present-day Hungarian, 65 present-day Sekler, and 23 ancient samples were successfully genotyped for the C/T-13910 SNP by the dCAPS PCR-RFLP method. Additional mitochondrial DNA testing was also carried out. In ancient Hungarians, the T-13910 allele was present only in 11% of the population, and exclusively in commoners of European mitochondrial haplogroups who may have been of pre-Hungarian indigenous ancestry. This is despite animal domestication and dairy products having been introduced into the Carpathian basin early in the Neolithic Age. This anomaly may be explained by the Hungarian use of fermented milk products, their greater consumption of ruminant meat than milk, cultural differences, or by their having other lactase-regulating genetic polymorphisms than C/T-13910. The low prevalence of lactase persistence provides additional information on the Asian origin of Hungarians. Present-day Hungarians have been assimilated with the surrounding European populations, since they do not differ significantly from the neighboring populations in their possession of mtDNA and C/T-13910 variants.

No mitochondrial haplotype was found to increase risk for alzheimer’s disease

BACKGROUND Seventy Alzheimers disease (AD) patients and 80 age- and sex-matched controls were analyzed for mitochondrial mutations T4336C and A3397G, reported to be associated with AD, and for mutations T4216C/G13708A characteristic for a normal human haplotype associated with increased frequency of occurrence of some hereditary diseases. The distribution of apolipoprotein E (apoE) alleles was also analyzed. METHODS Mitochondrial DNA was amplified by polymerase chain reaction, and the presence of mutations was detected by digestion with approximately chosen restriction endonucleases (restriction fragment length polymorphism). RESULTS One patient and 2 controls were found to belong to the T4336C/T1630C haplotype. No A3397G mutant was detected. The T4216C/G13708A haplotype occurred at 5/70 and 5/80 frequency in the two groups. Prevalence of the apoE4 allele was significantly higher in AD patients (25%) than in the control group (8.1%). CONCLUSIONS The T4336C/T16304C mutations were not found to associated with AD, and no predisposing mitochondrial haplotypes were found.

Centromere proteins - I. Mitosis specific centromere antigen recognized by anti-centromere autoantibodies

Human anti-centromere sera from scleroderma patients were used to detect centromere antigens of mouse fibroblast cells. An Mr=59000 centromere protein was localized exclusively on mitotic chromosomes. The association of this protein with the mitotic chromosomes proved to be DNase I sensitive. In interphase nuclei, this centromere antigen was not detectable by immunoblot techniques. The results suggest that the Mr=59000 mitosis specific protein may be necessary for the structural stability of kinetochores during mitosis.