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A Ziegler

Publications and source records attributed to A Ziegler.

At least 109 records · Page 6Linked to original sources
PubMed2000

Mapping of leukaemia-associated breakpoints in chromosome band 3q21 using a newly established PAC contig.

Chromosome aberrations affecting band 3q21 are associated with a particularly poor prognosis in patients with acute myeloid leukaemia. To facilitate the molecular characterization of such rearrangements, we established a PAC contig covering the relevant genomic region. Using these PACs as probes in fluorescence in situ hybridization (FISH) experiments, we showed that a number of 3q21 breakpoints in patient samples map to a previously defined 'breakpoint cluster region'. Others, however, are located at varying distances centromeric of it. These results have important implications in the search for genes affected by 3q21 rearrangements.

Acute Disease↗
PubMed2000

Treatment with an anti-CD44v10-specific antibody inhibits the onset of alopecia areata in C3H/HeJ mice.

A murine CD44v10-neutralizing antibody has been reported to impair delayed-type hypersensitivity reactions. Because alopecia areata is characterized by a delayed-type hypersensitivity-like T cell mediated immune response, we addressed the question whether an anti-CD44v10-antibody influences the onset of alopecia areata. Therefore, we used the C3H/HeJ mouse model with the induction of alopecia areata in unaffected mice by the grafting of lesional alopecia areata mouse skin. Six grafted mice were injected (intraperitoneally) with anti-CD44v10, six grafted mice with anti-CD44standard, and six with phosphate-buffered saline only. After 11 wk phosphate-buffered saline injected animals on average had developed alopecia areata on 36.8% of their body. The onset of hair loss was slightly delayed and its extent reduced to 17.2% of their body in anti-CD44standard-treated mice. By contrast, five of six anti-CD44v10-treated mice did not show any hair loss and one mouse developed alopecia areata on only 1% of the body. Immunohistochemical examination revealed a marked reduction of perifollicular CD8+ lymphocytes and, to a lesser degree, CD4+ cells as well as a decreased expression of major histocompatibility complex class I on hair follicle epithelium in anti-CD44v10-treated mice as compared with phosphate-buffered saline or anti-CD44 standard-treated mice. Our data show that anti-CD44v10 is able to inhibit the onset of alopecia areata in C3H/HeJ mice. This might be accomplished by an anti-CD44v10-triggered impairment of immune cell homing (e.g., CD8+ T cells), resulting in a decrease of their number in target tissues.

Alopecia Areata↗
PubMed2000

Surface expression of HLA-C antigen by human extravillous trophoblast.

In this paper definitive evidence that the classical class I product, HLA-C, is expressed on the surface of normal trophoblast cells is provided. HLA-C transcripts were sequenced from cDNA isolated from first trimester trophoblast cells obtained by flow cytometric sorting. Both paternal and maternal alleles were transcribed. HLA-C proteins were demonstrated by biochemical analysis and found on the cell surface in association with beta(2)-microglobulin. Upregulation of cell surface HLA-C but not HLA-G expression after interferon (IFN)-gamma treatment was demonstrated by flow cytometric analysis. Immunohistology has confirmed HLA-C is expressed by all extravillous subpopulations in vivo. The question of whether trophoblast HLA-C molecules interact with decidual NK cells expressing killer Ig-like receptors (KIR) has also been addressed. Our results demonstrate that extravillous trophoblast expresses at least two HLA class I molecules, HLA-G and HLA-C on the cell surface.

Adult↗
PubMed2000

Multiple primaries in pancreatic cancer patients: indicator of a genetic predisposition?

BACKGROUND: The genetic basis of several familial cancers including breast and colon cancers has been identified recently. The occurrence of multiple cancers in one individual is also suggestive of a genetic predisposition. To evaluate inherited predisposition in pancreatic cancer we compared the clinical data of pancreatic cancer patients with and without multiple primaries as well as the frequency of malignancies among their relatives. METHODS: Detailed data on 69 pancreatic cancer patients included survival time and TNM-classification. Index case data were separated into two groups. The first group (group 1) developed only pancreatic cancer during their lifetime, whereas the second group (group 2) developed additional primary tumours. A systematic family history was taken from 59 of these pancreatic cancer patients using a standardized questionnaire. The pancreatic cancers and the multiple primaries of the 59 patients were histologically proven. RESULTS: Of the 69 pancreatic cancer patients, 13 (18.8%) had multiple primaries. Neither the clinical data nor the survival data of the index cases revealed differences between the two groups (all nominal P-values >0.05). In the family history study blood relatives developed a malignancy in 51% (24 of 47) of the families in group 1 compared to 75% (9 of 12) in group 2. The risk of relatives in group 2 of developing a malignant tumour was significantly higher (P = 0.034) than in group 1 after adjustments for family size and age of disease onset of the index case. The cancer spectrum of the 59 families mainly included tumours of the digestive tract and the reproductive organs. CONCLUSIONS: A multiple primary cancer history is a common condition among pancreatic cancer patients. Relatives of these patients seem to have an increased risk for the development of distinct malignant solid tumours, which might be caused by an inherited predisposition. Clinical and genetic investigation of pancreatic cancer patients with multiple primaries and their families might lead to the identification of predisposing gene defects providing a new goal for the understanding of a shared genetic basis of different solid tumours.

Aged↗
PubMed2000

Aphid transmission studies using helper component proteins of potato virus Y expressed from a vector derived from potato virus X.

The genes encoding the helper component (HC) proteins of two strains of Potato virus Y (PVY) were cloned and the proteins expressed from a vector derived from Potato virus X (PVX). The expressed HC contained six N-terminal histidine residues to facilitate purification by metal affinity chromatography. Approximately 2-4 microg/g of purified HC was obtained from leaves of Nicotiana benthamiana plants systemically infected by recombinant PVX. Preparations of the HC protein derived from PVY ordinary strain (PVY(o)) assisted aphid transmission of purified particles of PVY(o) and PVY strain C (PVY(c); a naturally occurring non-aphid transmissible strain of PVY which contains a defective HC), as well as Potato aucuba mosaic virus. The HC derived from PVY(c) contained the Glu-Ile-Thr-Cys (EITC) motif, and mutation of Glu (E) to Lys (K) enabled the mutant PVX-expressed preparations to assist virus transmission by aphids. Expression of HC protein from the PVX vector produced biologically active protein. This approach should facilitate further studies to elucidate more precisely the molecular mechanism of virus transmission by aphids.

Amino Acid Sequence↗
PubMed2000

MHC-linked olfactory receptor loci exhibit polymorphism and contribute to extended HLA/OR-haplotypes.

Clusters of olfactory receptor (OR) genes are found on most human chromosomes. They are one of the largest mammalian multigene families. Here, we report a systematic study of polymorphism of OR genes belonging to the largest fully sequenced OR cluster. The cluster contains 36 OR genes, of which two belong to the vomeronasal 1 (V1-OR) family. The cluster is divided into a major and a minor region at the telomeric end of the HLA complex on chromosome 6. These OR genes could be involved in MHC-related mate preferences. The polymorphism screen was carried out with 13 genes from the HLA-linked OR cluster and three genes from chromosomes 7, 17, and 19 as controls. Ten human cell lines, representing 18 different chromosome 6s, were analyzed. They were from various ethnic origins and exhibited different HLA haplotypes. All OR genes tested, including those not linked to the HLA complex, were polymorphic. These polymorphisms were dispersed along the coding region and resulted in up to seven alleles for a given OR gene. Three polymorphisms resulted either in stop codons (genes hs6M1-4P, hs6M1-17) or in a 16-bp deletion (gene hs6M1-19P), possibly leading to lack of ligand recognition by the respective receptors in the cell line donors. In total, 13 HLA-linked OR haplotypes could be defined. Therefore, allelic variation appears to be a general feature of human OR genes.

Alleles↗
PubMed2000

Independent confirmation of a major locus for obesity on chromosome 10.

Linkage results obtained in genome-wide scans for complex phenotypes require confirmation in independent samples. Recently, linkage of obesity to chromosome 10p12 with a maximal multipoint LOD score of 4.85 was reported upon use of an affected sib-pair approach including nuclear families in which the adult index case had a BMI > or = 40 kg/m2 and at least one further sibling had a BMI > or = 27 kg/m2 (Hager et al., 1998, Nat Genet 20:304-8). To attempt to replicate this linkage finding we genotyped 11 markers spanning approximately 23 cM from 10p13 to 10ql1 in a total of 386 individuals stemming from 93 nuclear families with two or more young obese offspring with a BMI > or = 90th age percentile. The highest multipoint maximum likelihood binomial (MLB) LOD score using the extreme concordant sib-pair approach in which one sib had a BMI > or = 95th percentile, and other sibs a BMI > or = 90th percentile was 2.32. Six markers yielded nominal p-values < 0.05, the highest two point MLB-LOD score of 2.45 (nominal p = 0.0004) was obtained for the marker TCF8. Transmission disequilibrium tests for the most frequent parental allele yielded no nominal p-value < 0.05. The linkage results confirm the presence of a major susceptibility locus for obesity in a region near the centromere on chromosome 10.

Adult↗
PubMed2000

Effects of potassium channel inhibitors on the relaxation induced by the nitric oxide donor diethylamine nitric oxide in isolated human cerebral arteries.

OBJECT: The goal of this study was to investigate whether K+ channels are involved in nitric oxide (NO)-induced relaxation of isolated human cerebral arteries. METHODS: Successive concentration-response curves relating to the use of the NO donor diethylamine NO (DEA/NO) were established in the absence and presence of different K+ channel inhibitors after mounting human cerebral arteries onto a wire myograph. The arteries were obtained from macroscopically intact tissue that had been removed during brain tumor operations. A high K+ concentration partially inhibited the relaxant effects of DEA/NO. Different K+ channel inhibitors (tetraethylammonium [TEA], 10(-3) M; charybdotoxin, 10(-7) M; glibenclamide, 10(-6) M; 4-aminopyridine [4-AP], 10(-3) M; BaCl2, 5 x 10(-5) M; and apamin, 10(-6) M) alone failed to affect the responses to DEA/NO. However, a combination of TEA, glibenclamide, 4-AP, and BaCl2 partially blocked the relaxant effects of DEA/NO. In addition, the effects of DEA/NO were inhibited by the thromboxane A2 analog U46619 (3 x 10(-7) M). CONCLUSIONS: Inhibitors of the large-conductance or small-conductance Ca++-activated K+ channels, the adenosine triphosphate-sensitive K+ channels, and the delayed-rectifier or inward-rectifier K+ channels failed to alter the effects of DEA/NO when only one K+ channel blocker was used. However, a regimen of a combination of K+ channel blockers that possess selectivity for different channels demonstrated that different K+ channel types are involved; these channels may function in a redundant manner and compensate for each other. Selective thromboxane A2 agonists are capable of inhibiting the relaxant response to the NO donor.

Cerebral Arteries↗
PubMed2000

Characterization of the major metabolites of verapamil as substrates and inhibitors of P-glycoprotein.

Verapamil is subject to extensive oxidative metabolism mediated by cytochrome P450 enzymes with less than 5% of an oral dose being excreted unchanged in urine. Furthermore, verapamil is known to be a potent inhibitor of P-glycoprotein function. There is evidence from in vivo investigations that some verapamil metabolites might be actively transported. The aim of the present study was to investigate P-glycoprotein-mediated transport and inhibition properties of verapamil and its metabolites norverapamil, D-620, D-617, and D-703. Polarized transport of these compounds was assessed in P-glycoprotein-expressing Caco-2 and L-MDR1 cells (LLC-PK1 cells stably transfected with human MDR1-P-glycoprotein). Inhibition of P-glycoprotein-mediated transport by these compounds was determined using digoxin as P-glycoprotein substrate. At concentrations of 5 microM, significant differences between basal-to-apical and apical-to-basal apparent permeability coefficients were observed for D-617 and D-620 in all P-glycoprotein-expressing cell monolayers, indicating that both are P-glycoprotein substrates. In contrast, no P-glycoprotein-dependent transport was found for verapamil, norverapamil, and D-703 in Caco-2 cells and for D-703 in L-MDR1 cells. Moreover, verapamil, norverapamil, and D-703 inhibited P-glycoprotein-mediated digoxin transport with IC(50) values of 1.1, 0.3, and 1.6 microM, respectively, whereas D-617 and D-620 did not (at concentrations up to 100 microM). We conclude that verapamil phase I metabolites exhibit different P-glycoprotein substrate and inhibition characteristics, with the N-dealkylated metabolites D-617 and D-620 being P-glycoprotein substrates and norverapamil and D-703 being inhibitors of P-glycoprotein function, which may influence P-glycoprotein-dependent drug disposition and elimination.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

No evidence for involvement of polymorphisms of the dopamine D4 receptor gene in anorexia nervosa, underweight, and obesity.

Family and twin studies suggest a genetic contribution to the etiology of anorexia nervosa (AN) and obesity. Genes involved in weight regulation can be considered as candidate genes for AN. The dopaminergic system has been implicated in weight regulation; previous results had suggested a possible involvement of the dopamine D4 receptor gene (DRD4). We screened for alleles of two different polymorphisms (13-bp deletion, 48-bp repeat) in the DRD4. For association tests, allele frequencies were compared between 109 inpatients with AN, 82 underweight students, and 327 extremely obese children and adolescents. For application of transmission disequlibrium tests (TDT) we additionally genotyped 57 and 137 trios comprising a patient with AN or an extremely obese child or adolescent, respectively, and both parents. All genotyping was performed with polymerase chain reaction fragment length polymorphism analyses. None of the association tests or TDT rendered nominal P values below 0.1. An influence of alleles of the DRD4 on the development of AN, underweight, or extreme early onset obesity was not detected. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:594-597, 1999.

Adolescent↗
PubMed1999

Linkage disequilibrium of MTHFR genotypes 677C/T-1298A/C in the German population and association studies in probands with neural tube defects(NTD).

A number of studies have demonstrated that the common polymorphism 677C-->T in the gene encoding 5, 10-methylenetetrahydrofolate reductase (MTHFR) leads to a thermolabile variant with decreased enzyme activity and to mildly elevated plasma homocysteine. 677TT homozygosity was shown to be more frequent in NTD probands compared with controls in some studies. Recently, another polymorphism, 1298A-->C, in the MTHFR gene was described and combined heterozygosity 677CT/1298AC was suggested to be an additional risk factor for NTD. The present study examines the genotype and haplotype distribution of the two polymorphisms in the German population and evaluates the impact on NTD individuals and their relatives. To determine the haplotype of all individuals tested, we developed an easy-to-perform ARMS-RFLP test. Our data show that the two polymorphisms are in linkage disequilibrium in the general population and in NTD individuals. There was no statistically significant difference in allele and genotype frequency between probands (patients, fetuses) and controls (P > 0.10) and between observed and expected values for mother-child pairs (P > 0.80). Taking into account gender, an increased rate of 677CT heterozygotes was found in affected and unaffected males compared to affected and unaffected females. A family-based association study using a multiallelic transmission disequilibrium test (TDT) also shows that transmission rates do not deviate significantly from equilibrium (P > 0.50). Thus, our data provide no evidence for an association between NTD phenotype and MTHFR 677C/T-1298A/C genotypes and haplotypes.

Alleles↗
PubMed1999

Association analysis of exonic variants of the gene encoding the GABAB receptor and idiopathic generalized epilepsy.

The gene encoding the GABAB receptor (GABABR1) maps close to the HLA-F locus on chromosome 6p21.3 in the same region to which a major susceptibility locus for common subtypes of idiopathic generalized epilepsy (IGE), designated as EJM1, has been localized. Moreover, animal models suggest that the GABAB receptor plays a critical role in the epileptogenesis of absence seizures. Accordingly, the present association study tested the candidate gene hypothesis that genetic variants of the human GABABR1 gene confer susceptibility to common subtypes of IGE. Three DNA sequence variants in exons 1a1, 7, and 11 of the GABABR1 gene were assessed by PCR-based restriction fragment length polymorphisms in 248 unrelated probands of German descent, comprising 72 patients with juvenile myoclonic epilepsy (JME), 46 patients with idiopathic absence epilepsy (IAE), and 130 control subjects without a history of epileptic seizures and lack of generalized spike-wave discharges in their electroencephalogram. The results revealed no evidence for an allelic association of any of the GABABR1 sequence variants with either JME or IAE (P > 0.18). Thus, we failed to demonstrate that any of the three exonic GABABR1 variants themselves, or other so-far unidentified mutations, which are in strong linkage disequilibrium with the investigated variants, are involved in the pathogenesis of common IGE subtypes.

Adolescent↗
PubMed1999

Decamer-like conformation of a nona-peptide bound to HLA-B*3501 due to non-standard positioning of the C terminus.

The N and C termini of peptides presented by major histocompatibility complex (MHC) class I molecules are held within the peptide binding groove by a network of hydrogen bonds to conserved MHC residues. However, the published structure of the human allele HLA-B*3501 complexed with the nef octa-peptide VPLRPMTY, revealed non-standard positioning for both peptide termini. To investigate whether these deviations are indeed related to the length of the nef-peptide, we have determined the structure of HLA-B*3501 presenting a nona-peptide to 2.5 A resolution. A comparison of HLA-B*3501/peptide complexes with structures of other HLA molecules exhibits allele-specific properties of HLA-B*3501, as well as peptide-induced structural changes. Independent of the length of the bound peptide, HLA-B*3501 positions the peptide C terminus significantly closer to the alpha1-helix and nearer to the A pocket than observed for other HLA class I/peptide complexes. This reorientation is accompanied by a shift within the N-terminal part of the alpha2-helix towards the middle of the binding groove. Due to the short distance between the N and C termini, the nona-peptide is compressed and forced to zig-zag vertically within the binding groove. Its conformation rather resembles that of a deca-peptide than of other nona-peptides bound to class I molecules. Superposition of both HLA-B*3501/peptide complexes additionally reveals a significant, peptide-dependent deviation between the N-terminal parts of the alpha1-helices which might be due to different positioning of the peptide N termini. Taken together, these data illustrate the strong interdependence between the HLA class I molecule and the bound peptide.

Alleles↗
PubMed1999

Low-temperature polarized helium-3 for MRI applications.

The first 3He nuclear magnetic resonance (NMR) experiments using low-temperature prepolarization are presented. 3He cells were polarized at 4.2 K and 4.7 T, transported to another magnet, heated to room temperature, and used for NMR experiments at 2.35 T. Cells with and without a rubidium coating were tested. In both cases, the NMR signal was greater than 100 times the thermal equilibrium signal. No evidence of a rubidium coating effect on the longitudinal relaxation time T1 of 3He (500 mbar) at 4.2 K could be demonstrated. NMR gradient-echo images of the cells were acquired.

Helium↗
PubMed1999

Significant evidence for linkage of a simulated trait to D1G024--a conclusion reached using multiallelic transmission/disequilibrium tests.

We applied three versions of the transmission/disequilibrium test (TDT) for detecting linkage in nuclear families using the a priori information of possibly present association. For our analyses we employed all marker data for a simulated trait. Results for replicate 11 showed significant linkage to D1G024 using the multiallelic Tmhet statistic and the extended TDT. The TDT for the most frequent parental allele which had been applied successfully in previous studies failed to detect linkage. This result may have happened because the data did not arise from a realistic simulation of the evolution of a real population, where mutations might be expected to occur against a specific haplotype. Simulation studies are required to elucidate the applicability of the TDT for the most frequent parental allele in realistic situations. Furthermore, guidelines have to be developed for how to pool categories in large, sparse contingency tables to obtain larger cell frequencies and lower degrees of freedom.

Alleles↗