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Biomedical subjects

N Blin

Publications and source records attributed to N Blin.

At least 37 records · Page 2Linked to original sources
PubMed2001

Frequency of the recessive 30delG mutation in the GJB2 gene in Northeast-Hungarian individuals and patients with hearing impairment.

Mutations in the GJB2 gene, which encodes a gap junction protein (connexin 26) account for up to 50% of cases of congenital autosomal recessive non-syndromic hearing impairment. A single mutation, 30delG, is responsible for 70% of this autosomal recessive hearing loss in Europe. This study describes the 30delG mutation analysis of 23 Hungarian families (64 individuals) with at least two subjects with congenital non-syndromic hearing defect and of 52 unrelated individuals from the Northeastern population of Hungary. In all patients, non-progressive hearing impairment varied from moderate to profound involving all frequencies. DNA was tested by PCR based restriction enzyme assay (BSiYI). Sixty-four percent of the patients displayed this one base deletion in GJB2. Out of these, 65.9% were homozygous for this mutation and 34.1% were heterozygotes. The latter showed compound heterozygosity since in these 14 patients, eight previously reported different nucleotide changes were observed on the second allele. The carrier frequency of the 30delG mutation among control group was one in 10.4 (9.6%). This high frequency of 30delG corresponds more to frequencies reported in Southern than in North Europeans.

Adolescent↗
PubMed2001

Comparative genomic hybridization analysis of chromosomal alterations in patients with long-standing ulcerative colitis.

Patients with ulcerative colitis (UC) are prone to develop colorectal cancer which is related to the duration and extent of the disease. One of the earliest events in tumor progression is the development of aneuploidy. Aneuploidy is correlated with the grade of dysplasia which serves as a common but not always reproducible marker for the prediction of UC associated formation of cancer. We analyzed 48 biopsy samples from 5 patients with long-standing ulcerative colitis by comparative genomic hybridization (CGH). The majority of these samples represented premalignant stages which are not well characterized at the molecular level as yet. We compared biopsy samples from different colon locations in regard to chromosomal alterations, dysplasia status and DNA index. Besides chromosomal changes occurring only in certain patients in restricted areas of the colon we also detected amplifications and deletions which were common in all persons throughout the colon. The stage of dysplasia seems to have no influence on the number and appearance of chromosomal changes. Amplifications in 2, 3, 6, 9, 11, 12 and 15 were found in almost all cases. In dysplastic samples chromosomal regions 3, 6 and 11 revealed gains of DNA. Deletions were detected within 8q, 15, 18q, 20p and 22q. The affected chromosomal regions may contain yet unknown oncogenes or tumor suppressor genes participating in UC associated carcinogenesis. The conspicuous regions found in the CGH experiments allow the selective and detailed characterization at a molecular level.

Chromosome Aberrations↗
PubMed2000

Transcription factor GATA-6 activates expression of gastroprotective trefoil genes TFF1 and TFF2.

One of the early events in inflammation and epithelial restitution of the gastrointestinal tract is the up-regulation of secretory peptides belonging to the trefoil factor family (TFF) that promote cell migration, protect and heal the mucosa. Their major expression site is stomach (TFF1, TFF2) and intestine (TFF3). Located in the 5'-flanking region of the genes are several consensus sites for members of the GATA transcription factors known to control gut-specific gene expression. By reverse transcription-PCR (RT-PCR), GATA-6 was shown to be expressed in a variety of tumor cell lines of gastric, intestinal and pancreatic origin. In MKN45, KATOIII and LS174T, cotransfection with TFF reporter genes and GATA-6 expression vectors revealed that GATA-6 activates TFF1 and TFF2 4-6-fold, without an effect on TFF3. The functional contribution of GATA binding sequences in the reverse orientation was further characterized by reporter gene assays using TFF2 deletion constructs and by gel shift experiments.

Adenocarcinoma↗
PubMed2000

[Mutational analysis of the connexin26 gene in sporadic cases of moderate to profound deafness].

Non-syndromic neurosensory recessive deafness (NSRD) is one of the most common human sensory disorders. Mutations in the connexin 26 gene have been established as a major cause of inherited and sporadic non-syndromic deafness in different populations. The CX26 gene encodes the gap junction protein connexin 26 (beta-2, GJB2), whose expression was shown in several tissues and in the cochlea. The 30delG mutation is the most frequent mutation in the CX26 gene. It represents a deletion of guanosine (G) in a sequence of six Gs extending from position 30 to 35 of the CX26 cDNA. The deletion creates a frameshift resulting in a premature stop codon and a non-functional intracellular domain in the protein. The 30delG mutation can be detected at the molecular level using PCR followed by BsiYI digestion. We screened 164 mainly German patients with non-syndromic sporadic deafness for this mutation to determine its distribution in the German population. The frequency of the mutation in our analyzed patients was lower than in other studies and therefore indicates its dependency on geographically distinct populations.

Audiometry, Pure-Tone↗
PubMed2000

Microsatellite instability in thyroid papillary carcinoma and multinodular hyperplasia.

Microsatellite instability (MSI) is a molecular landmark of mutations in DNA mismatch repair genes. The impaired efficiency of DNA repair mechanisms promotes carcinogenesis as well as contributes to tumour progression. Until now, only few studies on MSI in thyroid tumours have been published. Therefore, the aim of the present study was to investigate MSI as a possible characteristic feature of thyroid tumours. The analysis of 12 thyroid papillary carcinomas and 17 multinodular hyperplasias at 13 microsatellite loci showed MSI and loss of heterozygosity (LOH) in both types of lesion, with more alterations noted in the papillary thyroid carcinomas (in 65%) than in multinodular hyperplasia (in 35%). In carcinomas, LOH occurred more frequently than MSI, while in multinodular hyperplasia the LOH/MSI ratio is almost equal.

Adolescent↗
PubMed2000

Frequent D-loop polymorphism in mtDNA enables genotyping of 1400-year-old human remains from Merowingian graves.

Improvements of DNA extraction and amplification techniques presently enable DNA analysis of ancient DNA (aDNA) from samples which range from several hundred years of age up to possibly 5000 years. Taking advantage of the abundance of mitochondrial DNA and its polymorphic D-loop sequence, ten individuals from multiple burial sites of the Merowingian culture (South Germany), estimated to be about 1400 years old, were genotyped to determine possible kinship. Moreover, gonosomal DNA markers from the X- and Y-chromosome were applied for sex determination of the remains. In all individuals investigated, deviations from the Anderson mtDNA consensus sequence were observed, all representing substitutions (7 transitions and 3 transversions). Although such mutations have been reported from recent populations, our study constitutes the first description of these mtDNA mutations from numerous aDNA samples recovered from multiple burial sites. The results obtained by molecular anthropology can aid in describing kinship relations and burial customs of ancient remains.

Journal Article↗
PubMed2000

Adaptor-mediated amplification of minute amounts of severely fragmented ancient nucleic acids.

It has been repeatedly shown that high copy number mitochondrial DNA sequences can be recovered from ancient samples. A significant increase in the volume of information available to researchers will be observed when the amplification of nuclear DNA becomes commonplace and reproducible. To this end we established a modification of the Rapid Amplification of cDNA Ends (RACE) procedure normally used for the generation of cDNA ends from adaptor-ligated expressed sequence tag libraries. The modifications were designed to specifically address the problems associated with the highly damaged nucleic acids extracted from palaeontological specimens. For this study we used 6 human samples dating to 450 AD and approximately 6.500 BP that were refractory to reliable amplification of single copy loci by PCR. Racemate contents (ratio of D/L enantiomers) of aspartic acid, alanine, and leucine also indicated that no amplifiable DNA is present in 5 of the 6 samples. The proposed technique allowed us (i) to amplify four X-chromosomal loci from 5 human specimens, and (ii) to correct allelic drop-out phenomena at the amelogenin locus in one individual; thus showing that the threshold of 80 x 10-3 for D/Lasp as a borderline for the presence/absence of amplifiable aDNA requires reassessment. Reliability of the proposed technique (i.e. amplification of DNA sequences endogenous to the find) was validated by the application of "ancient RACE" (aRACE) to prehistoric animal samples.

Journal Article↗
PubMed1999

Tracing the evolutionary origin of the TFF-domain, an ancient motif at mucous surfaces.

Mammalian trefoil factor family (TFF)-domain peptides promote gastrointestinal protection, healing and cell migration and may act as tumour suppressors. TFF-like domains also constitute modules of composite proteins like mucin glycoproteins and zona pellucida proteins. Database searches with a modified, less stringent consensus sequence - C-x(5,6)-[ST]-x(3)-C-x(4,5)-C-C-[FYWH]-x(2, 24)-C-[FY] - revealed that ancestors of the TFF-domain arose before amphibian evolution. Eggshell proteins and a zona pellucida-like protein in teleost species, an epidermis-specific protein in a tunicate as well as an open reading frame in a nematode exhibited TFF-like motifs suggesting that they most likely originated in some multicellular organism.

Amino Acid Sequence↗
PubMed1999

Differential expression of mucins and trefoil peptides in native epithelium, Barrett's metaplasia and squamous cell carcinoma of the oesophagus.

BACKGROUND AND AIMS: In humans, trefoil peptides (TFF peptides) and some mucins have been reported to be expressed in a cell-specific manner at mucosal surfaces of normal gastrointestinal tissues. Neoplastic conditions cause characteristic changes of these expression patterns. To study such patterns in Barrett's metaplasia and squamous cell carcinoma of the oesophagus (SCC), the distribution of MUC1, MUC2, MUC5AC and the three TFF peptides (TFF1, TFF2 and TFF3) was investigated. METHODS: In 40 archival samples of SCC and in 21 samples of Barret's metaplasia, expression of the three mucins and two TFF peptides (TFF1 and TFF2) was assessed by specific antibodies. Reverse transcriptase/polymerase chain reaction amplification (RT-PCR) was performed on frozen tissue samples from the 11 biopsies of SCC for the three TFF peptides. RESULTS: Immunohistochemical tests for MUC2 and TFF2 were negative both in samples of Barret's metaplasia and in SCC. MUC1 expression was detected in 57.5% of the tumour samples, while TFF1 and MUC5AC were found in 10% and 7.5% of the cases respectively. In Barrett's metaplasia MUC1 was detected in 90.5% of the cases and TFF1 and MUC5AC in all of them. RT-PCR analysis revealed a more complex pattern: TFF1 and TFF3 expressed the corresponding mRNA in all samples investigated; the third member, TFF2, was active in 45.5% of the carcinoma biopsies and not in the corresponding native tissue. CONCLUSIONS: This finding in oesophageal carcinoma contrasts with the situation found in normal and neoplastic stomach epithelium where TFF1 and TFF2 are found co-expressed and TFF3 remains silent. Interestingly, MUC1 is expressed in a significant proportion of SCC. Both in Barett's metaplasia and in SCC the expression of MUC5AC mirrors the TFF1 synthesis in intensity and spatial distribution.

Adult↗
PubMed1999

Hepatocyte nuclear factor 3 (winged helix domain) activates trefoil factor gene TFF1 through a binding motif adjacent to the TATAA box.

The winged helix transcription factors HNF-3/FKH (forkhead homologs) activate endodermal-derived and acute-phase gene expression and control gut development in Drosophila. Trefoil factor family (TFFs) peptides are vertebrate products secreted by mucin-producing epithelial cells of the gastrointestinal tract involved in restitution and repair of the mucosa. They are positively regulated in ulcerative and neoplastic conditions. We describe a consensus sequence in human and rodent TFF promoters close to the TATAA box showing striking similarity to the binding site of the HNF-3/FKH family. In gel retardation assays, HNF-3 alpha and beta bound predominantly to the site in TFF1 (formerly pS2) and, to a lesser extent, to the sites in TFF2 or TFF3. Mutations generated in this motif severely impaired transcription of TFF1 reporter genes. Cotransfection with expression vectors of HNF-3alpha and beta, but not the related HFH 11A and B, specifically activated the wild-type TFF1 reporter genes. Activation of endogenous expression of TFF1 by HNF-3 alpha and beta gene products was more than 1000 fold in the pancreatic cell line Capan-2 and fivefold in the gastric cell line MKN-45, whereas the intestinal cell lines HUTU 80 and HT-29 displayed no effect. Thus, HNF-3/FKH factors contribute causally to cell-specific regulation of TFF genes and may explain the acute-phase response of TFF peptides.

Animals↗
PubMed1999

Variable distribution of TFF2 (Spasmolysin) alleles in Europeans does not indicate predisposition to gastric cancer.

Peptides belonging to the trefoil factor family (TFF) protect the gastrointestinal epithelia. Overexpression of TFFs was observed in pathological conditions such as gastritis, ulceration, metaplasia and neoplasia of the gastrointestinal tract. The aims of this work were to investigate the recently described TFF2 gene polymorphism in different European populations. DNA samples from blood of healthy individuals and gastric cancer patients were genotyped using the polymerase chain reaction. They were compared to a gastric cancer population. The results do not show any significant difference in allelic frequencies between gastric cancer patients and healthy individuals from Portugal. However, the frequency of the two alleles found varies considerably among Europeans.

Alleles↗
PubMed1999

E-cadherin gene mutations provide a genetic basis for the phenotypic divergence of mixed gastric carcinomas.

Inactivation of the E-cadherin gene has been described previously in gastric carcinomas. In the present study, we investigated the alterations of the E-cadherin gene in gastric carcinomas and analyzed the relationship between such alterations and the histotypes of the tumors. We performed PCR/single-strain conformation polymorphism mutation screening and loss of heterozygosity analysis of the E-cadherin gene in a series of 26 gastric carcinomas, including 10 "pure" intestinal, 10 "pure" diffuse, and 6 mixed gastric carcinomas, the latter with intestinal and diffuse components. Fifteen mutations of the E-cadherin gene were identified in 12 cases (46.2%). Mutations included 10 missense mutations, 7 of which occurred in sequences coding for calcium binding motifs, 3 splice site mutations, 1 nonsense mutation, and 1 frameshift deletion. We found mutations of the E-cadherin gene in 7 of 10 "pure" diffuse carcinomas (70.0%) and in 5 of 6 mixed carcinomas (83.3%). No mutations were found in "pure" intestinal carcinomas. In mixed carcinomas, inactivating E-cadherin mutations were exclusively observed in the diffuse component of the tumors. We conclude that E-cadherin inactivation is significantly related with the diffuse histotype in gastric carcinomas, not only in "pure" diffuse carcinomas but also in the diffuse component of mixed tumors. To the best of our knowledge, this is the first report advancing a genetic basis for the phenotypic divergence of mixed gastric carcinomas.

Cadherins↗
PubMed1998

Osmotic changes and ethanol modify TFF gene expression in gastrointestinal cell lines.

The gastrointestinal tract is exposed to environmental insult as a result of food intake or in pathological conditions such as diarrhoea, and is therefore protected by the mucus layer. As part of it, trefoil peptides (TFFs) are able to modify the visco-elastic properties of the mucus, protect against experimental ulceration, and promote repair of the epithelia. We investigated, using transient reporter gene assays and RT-PCR in the gastric carcinoma cell line MKN45 and colon carcinoma cell lines LS174T and HT29, whether ethanol and osmotic changes can modify transcriptional activity of TFFs. In a mild hypotonic environment (200 mosmol/l) all three TFF genes were up-regulated by at least a factor of 2. In hypertonic medium (400 mosmol/ll), TFF1 and TFF3 were down-regulated, whereas TFF2 was up-regulated by elevated concentrations of sodium or chloride in MKN45. Raising the osmolality by ethanol resulted in an up-regulation of TFF3 in both colon cell lines but not in the gastric cell line. We conclude that alteration in TFF gene expression is a response of gut epithelia to deal with osmotic forces and ethanol.

Digestive System↗
PubMed1998

Deletion mapping by FISH with BACs in patients with partial monosomy 22q13.

Patients with deletions in 22q13 are known to have phenotypic features that include normal or accelerated growth, large hands and feet, hypotonia, delayed psychomotor development and mild facial dysmorphism. To date, very few cases have been investigated by detailed molecular genetic analysis. We have analyzed three new patients with terminal deletions in 22q. We compared the cytogenetic observations with molecular data assessed by fluorescence in situ hybridization and an array of characterized bacterial artificial chromosome recombinants. The shortest region of deletion overlap is localized in 22q13.2-qter distal to the marker D22S94, but the telomeric repeat in the deleted chromosome appears to remain intact. When parental alleles were investigated in two of the three patients, the aberrant homolog was found to be of paternal origin in both cases. Although the deleted region still spans >20 cM, molecular analysis of additional patients and screening for new genes might help in elucidating candidate genes connected with the dysmorphisms defined by deletions of 22q13.

Child, Preschool↗
PubMed1998

The SOX10/Sox10 gene from human and mouse: sequence, expression, and transactivation by the encoded HMG domain transcription factor.

The SOX genes form a gene family related by homology to the high-mobility group (HMG) box region of the testis-determining gene SRY. We have cloned and sequenced the SOX10 and Sox10 genes from human and mouse, respectively. Both genes encode proteins of 466 amino acids with 98% sequence identity. Significant expression of the 2.9-kb human SOX10 mRNA is observed in fetal brain and in adult brain, heart, small intestine and colon. Strong expression of Sox10 occurs throughout the peripheral nervous system during mouse embryonic development. SOX10 shows an overall amino acid sequence identity of 59% to SOX9. Like SOX9, SOX10 has a potent transcription activation domain at its C-terminus and is therefore likely to function as a transcription factor. Whereas SOX9 maps to 17q, a SOX10 cosmid has previously been mapped by us to the region 22q13.1. Mutations in SOX10 have recently been identified as one cause of Waardenburg-Hirschsprung disease in humans, while a Sox10 mutation underlies the mouse mutant Dom, a murine Hirschsprung model.

Adult↗
PubMed1998

Novel immunogenic antigen homologous to hyaluronidase in meningioma.

By screening a meningioma expression library with autologous serum we identified four cDNA clones representing a novel gene with striking homology to Caenorhabditis elegans hyaluronidase as indicated by BLASTP analysis. In humans hyaluronidase has been implicated in cancer development and three human genes are known to encode proteins with hyaluronidase activity. None of the human genes, however, showed any homology at the nucleotide or amino acid sequence level to the newly isolated antigen we termed meningioma expressed antigen 5 (MGEA5). Somatic cell hybrid mapping and fluorescence in situ hybridization mapped the gene for MGEA5 to chromosomal band 10q24.1-q24.3. Reverse transcription (RT)-PCR and northern blot hybridization revealed expression of the gene encoding MGEA5 in several meningioma and additional human tissues. Expression analysis also indicated an alternative splicing event giving rise to a shorter and altered transcript termed MGEA5s. The expression of MGEA5 and MGEA5s as fusion proteins revealed an approximate molecular weight of 92 and 54 kDa, respectively. Using heterologous sera we found antibodies against MGEA5s in five out of 23 meningioma patients, whereas no immune reaction was detected in 12 control sera from healthy individuals. Confirmation of hyaluronidase activity was independently achieved by turbidometric analysis and a gel matrix assay. A model for involvement of the novel hyaluronidase gene in meningioma development is proposed.

Acetylglucosaminidase↗
PubMed1998

Classical and molecular cytogenetic methods in diagnosis of a rare translocation t(3;21).

We report the characterization by traditional cytogenetic methods and fluorescence in situ hybridization (FISH) of a rare balanced reciprocal translocation t(3;21) in a male spouse connected with several miscarriages. G- and C-banding analysis of the male karyotype was suggestive of breakpoints in chromosomal bands 3q11.1 and 21p11.1. Multicolor-FISH analysis using chromosome-specific alpha-satellite probes in combination with a locus-specific bacterial artificial chromosome (BAC) from 21q22.3 allowed us both to identify the origin of centromeres in the derivative chromosomes and to establish centromere-telomere orientation of the translocated chromosome 21 segment. Characterization of the translocated chromosomes by FISH analysis permitted describing the exact karyotype of the carrier as: 46,XY,-3,-21,+der(3)(21qterO21q11. 2::3p11.2O cenO3qter),+der(21)(3pterO3p11.2::21q11.2OcenO21pte r).

Abortion, Spontaneous↗