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Biomedical subjects

A Ziegler

Publications and source records attributed to A Ziegler.

At least 199 records · Page 11Linked to original sources
PubMed1996

Genetic analysis of the epidermal differentiation complex (EDC) on human chromosome 1q21: chromosomal orientation, new markers, and a 6-Mb YAC contig.

The epidermal differentiation complex (EDC) unites a remarkable number of structurally, functionally, and evolutionarily related genes that play an important role in terminal differentiation of the human epidermis. It is localized within 2.05 Mb of region q21 on human chromosome 1. We have identified and characterized 24 yeast artificial chromosome (YAC) clones by mapping individual EDC genes, sequence-tagged site (STS) markers (D1S305, D1S442, D1S498, D1S1664), and 10 new region-specific probes (D1S3619-D1S3628). Here we present a contig that covers about 6 Mb of 1q21 including the entire EDC. Fluorescence in situ hybridization on metaphase chromosomes with two YACs flanking the EDC determined its chromosomal orientation and established, in conjunction with physical mapping results, the following order of genes and STSs: 1cen-D1S442-D1S498-S100A10-THH-FLG- D1S1664-IVL-SPRR3-SPRR1-SPRR2-LOR- S100A9-S100A8-S100A7-S100A6-S100A5-S100 A4- S100A3-S100A2-S100A1-D1S305-1qtel. These integrated physical, cytogenetic, and genetic mapping data will be useful for linkage analyses of diseases associated with region 1q21 and for the identification of novel genes and regulatory elements in the EDC.

Cell Differentiation↗
PubMed1996

The TAP complex influences allorecognition of class II MHC molecules.

The influence of the TAP complex on T-cell allorecognition of MHC class II molecules was examined using human B-cell lines that have mutations in the TAP 1 or 2 genes. The TAP mutations led to the loss of allorecognition for two of 28 anti- HLA-DR T-cell clones. Restoration of TAP expression by transfection of a TAP 2 cDNA clone led to recovery of the alloresponse for both clones. These results could be explained in two ways. First, TAP dependence could reflect specificity for a peptide derived from an MHC class I molecule that is less efficiently generated by the endocytic pathway in the TAP-deficient stimulator cells owing to reduction in surface class I expression. The proliferative responses of these clones to the TAP-deficient stimulator cells was not restored by rescue of cell-surface expression of class I molecules by low temperature culture or by the addition of class I-binding peptides. These data therefore favor the alternative explanation that class II loading by some peptides is TAP dependent. Circumstances that lead to the amplification of this minority pathway of endogenous presentation by class II MHC molecules may have the potential to interrupt self-tolerance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Ultrastructural evidence for transepithelial calcium transport in the anterior sternal epithelium of the terrestrial isopod Porcellio scaber (Crustacea) during the formation and resorption of CaCO3 deposits

Before the molt, terrestrial isopods store large amounts of calcium carbonate between the epithelium and the old cuticle of the first four anterior sternites. In order to test whether the anterior sternal epithelium has specific structural differentiations indicative of transepithelial ion transport, the anterior sternal epithelium and, as a control, the posterior sternal epithelium were studied using electron-microscopical techniques. During the formation of calcium carbonate deposits, the basolateral plasma membrane of the anterior sternal epithelium forms an elaborate interconnected network of interstitial dilations and channels. Numerous osmiophilic granules occur within this basolateral intercellular network during resorption of the calcium carbonate deposits. Electron energy-loss spectroscopy of the osmiophilic granules indicates that they contain calcium. During the resorption of the calcium carbonate deposits, the apical plasma membrane of the anterior sternal epithelium has many subcuticular folds. An interstitial network, osmiophilic granules, and apical, subcuticular folds do not occur in the posterior sternal epithelium. Taken together, these structural features are indicative of transepithelial ion transport and are probably necessary for the formation and resorption of the anterior sternal calcium carbonate deposits.

Journal Article↗
PubMed1996

Relationship between sunlight exposure and a key genetic alteration in basal cell carcinoma.

BACKGROUND: Basal cell carcinoma (BCC) of the skin is the most common cancer in humans. Epidemiologic studies implicate sunlight exposure as one risk factor, but the limited association between BCCs and UVB radiation (i.e., UV radiation of a wavelength of 280-320 nm) suggests that additional factors must be involved. At the molecular level, not much is known about the role of specific environmental agents in the pathogenesis of BCCs. Point mutations of the types produced by UVB radiation are seen in the p53 gene (also known as TP53; chromosome 17p) of 40%-56% of BCCs. Loss of heterozygosity (LOH) on chromosome 9q22, however, is the most frequent genetic alteration in these tumors, and its causative agent is unknown. PURPOSE: We investigated whether the genetic alteration in chromosome 9 is common to all clinical subtypes of BCCs and whether inactivation of this putative tumor suppressor is related to sunlight exposure. The presence of UVB radiation-related point mutations in the p53 gene was used as an internal control for sunlight exposure to the precursor cells. METHODS: Tumor and blood samples were obtained from skin cancer patients by a surgeon who used Mohs' micrographic surgical technique. Clinical information on each tumor included location, size, histologic, subtype and whether it was primary or recurrent and sporadic or hereditary. Sixty BCCs from 58 patients were evaluated for LOH with 12 polymorphic markers that span chromosome 9. A subset of 18 tumors was evaluated for point mutations in exons 2-11 of the p53 gene, and a subset of 26 tumors was evaluated for LOH by use of a polymorphism in exon 4 of the p53 gene. Associations between tumor characteristics and molecular alterations were tested by a two-tailed chi-squared analysis or a two-tailed Fisher's exact test, depending on sample size. RESULTS: In a clinically diverse series of 47 informative tumors, 32 (68%) showed LOH for chromosome 9q markers, irrespective of histologic characteristics or clinical behavior. Forty-four (94%) of the 47 tumors were from sun-exposed areas of the body, defined as the head and neck in both sexes, shoulders or chest in males, and legs in females. No association was found between chromosome 9q LOH and sunlight exposure, as assessed by either the location of tumors on the body or the presence of UVB radiation-related p53 mutations. Of note, there was a striking difference between the frequency of LOH on chromosome 17p (two [12.5%] of 16 informative tumors) and on chromosome 9q (32 [68%] of 47 informative tumors; P < .001). CONCLUSIONS: Inactivation of a gene on chromosome 9q22 may be a necessary event for basal cell carcinogenesis. The pathogenesis of mutations in this gene may involve factors other than sunlight in a large proportion of tumors. IMPLICATIONS: The limited association between sunlight exposure and BCC incidence may reflect an etiologic contribution of additional environmental agents.

Adult↗
PubMed1996

Correlation-peak imaging.

Identification and quantitation in conventional 1H spectroscopic imaging in vivo is often hampered by the small chemical-shift range. To improve the spectral resolution of spectroscopic imaging, homonuclear two-dimensional correlation spectroscopy has been combined with phase encoding of the spatial dimensions. From the theoretical description of the coherence-transfer signal in the Fourier-transform domain, a comprehensive acquisition and processing strategy is presented that includes optimization of the width and the position of the acquisition windows, matched filtering of the signal envelope, and graphical presentation of the cross peak of interest. The procedure has been applied to image the spatial distribution of the correlation peaks from specific spin systems in the hypocotyl of castor bean (Ricinus communis) seedlings. Despite the overlap of many resonances, correlation-peak imaging made it possible to observe a number of proton resonances, such as those of sucrose, beta-glucose, glutamine/glutamate, lysine, and arginine.

Ricinus communis↗
PubMed1996

Expression of HLA class I molecules in human first trimester and term placenta trophoblast.

Expression of HLA class I molecules in trophoblast cells from various locations in normal human first trimester and term placenta was investigated by immunohistochemistry with a panel of monoclonal antibodies against the heavy chains or complete HLA class I molecules complexed with beta2-microglobulin. These reagents were also employed to distinguish between the products of different HLA class I loci. In addition to previously characterized reagents, a novel monoclonal antibody against HLA-A molecules (TU155) was used. Various choriocarcinoma and transfected cell lines served as controls for the specificities of the monoclonal antibodies. Cells in close contact with maternal cells, such as invading trophoblast cells and cells of the basal plate, expressed beta2-m micro globulin in association with HLA-G and HLA-C heavy chains. These class I heavy chains may also have been present as isolated molecules, although not in each of the cells. In contrast, cells of the chorion laeve exclusively expressed HLA-G, and not HLA-A, -B, or -C antigens. Our data support the often discussed immune protective function and the regulatory function of the HLA-G molecule, during invasion. In addition, by using monoclonal antibodies HCA2 (anti-HLA-A and -G), HC10 (anti-HLA-B and -C), TU149 (anti-HLA-B, -C, and some -A alleles), SFR8-B6 (anti-HLA-Bw6 and some -C), LA45 (some HLA-A and -B), TU48 (anti-HLA-Bw4 and some -A), and TU155 (anti-HLA-A), we show the presence of HLA-C molecules in all extravillous trophoblast cells of the cell columns and in the basal plate; the trophoblast cells of the chorion laeve lack this antigen. The function of this molecule is not clear, although a protective function against natural killer cell activity in the endometrium is postulated.

Blotting, Western↗
PubMed1996

Gitelman's syndrome is genetically distinct from other forms of Bartter's syndrome.

In the past the term Bartter's syndrome has been used to describe a spectrum of inherited renal tubular disorders with hypokalemic metabolic alkalosis and overlapping and additional clinical and biochemical features. Pathogenesis remained uncertain until recently Gitelman's syndrome, the hypokalemic-hypomagnesemic variant with hypocalciuria, was linked to the gene encoding the thiazide-sensitive Na-Cl-cotransporter (TSC) located on chromosome 16q. Various mutations in the TSC gene were identified in patients with Gitelman's syndrome. To clarify whether different forms of hypokalemic tubular disorders (HTD) represent variable phenotypes of a common genetic defect, we performed linkage analyses in 17 families with different symptoms of HTD with four highly polymorphic chromosome 16 DNA markers closely linked to the TSC gene. Linkage of Gitelman's syndrome to the TSC locus was confirmed in our families with a maximum two-point Lod score Z = 4.70 (theta = 0.001) for marker locus D16S526. Highly negative LOD scores were obtained at this locus in our families with classic Bartter's syndrome (Z = 9.89, theta = 0.001) and hyperprostaglandin E syndrome (Z = -11.24, theta = 0.001). Our data prove that Gitelman's syndrome is genetically distinct from classic Bartter's syndrome and hyperprostaglandin E syndrome. It remains unknown if classic Bartter's syndrome and hyperprostaglandin E syndrome are caused by a common genetic defect.

Adolescent↗
PubMed1996

Synthesis, opioid receptor affinity, and enzymatic hydrolysis of sterically hindered morphine 3-esters.

With the intention of preparing prodrugs, 10 morphine 3-esters were synthesized and evaluated in vitro for opioid receptor binding and enzymatic hydrolysis. The results of binding assays performed on homogenates of guinea pig brain demonstrate a loss in affinity of morphine to mu-, delta-, and kappa-receptors by esterification at the 3-position. The conversion of the esters to morphine was determined in human plasma by HPLC analysis. The half-lives of hydrolysis ranged from 0.5 to > 300 h. The investigations indicate that esterification at the 3-position results in morphine prodrugs with variable hydrolytic stability. Sterically hindered morphine 3-esters may be a promising approach to manipulate the rate of release of morphine.

Animals↗
PubMed1996

The satellite RNAs associated with the groundnut rosette disease complex and pea enation mosaic virus: sequence similarities and ability of each other's helper virus to support their replication.

Pea enation mosaic virus (PEMV) and the causal agents of groundnut rosette disease are diverse examples of disease complexes involving two RNA species, one of which is related to the genomes of luteoviruses and the other to those of umbraviruses. In both complexes, these viral RNA components may be supplemented with satellite RNAs that are dependent on the umbravirus component for replication and systemic movement, and on the luteovirus component for encapsidation and vector transmission. Sequence analysis identified regions of similarity between the satellites of groundnut rosette virus (GRV) and PEMV, particularly at the 5' and 3' termini and around duplicate sequence repeats present in each satellite RNA. The umbravirus GRV and the umbravirus-like PEMV RNA-2 were each able to support the replication and systemic spread of homologous and heterologous satellites. The presence of the PEMV satellite in infections with GRV had no effect on symptom expression in Nicotiana spp. or in Arachis hypogaea. Likewise, in Pisum sativum, the GRV satellite had no effect on the symptoms induced by PEMV. However, the intense yellow blotch symptoms induced in Nicotiana benthamiana by the YB3 GRV satellite in conjunction with GRV were also manifested when PEMV was the helper. Although PEMV RNA-1 was capable of supporting the encapsidation and aphid transmission of the GRV satellite, no evidence was obtained that the essential role of the GRV satellite in the aphid transmission of GRV could be supplied by the PEMV satellite. These data further strengthen the hypothesis of an evolutionary relationship between PEMV and the luteovirus-umbravirus complexes.

Animals↗
PubMed1996

Genes encoding structural proteins of epidermal cornification and S100 calcium-binding proteins form a gene complex ("epidermal differentiation complex") on human chromosome 1q21.

Chromosome 1 reveals in region 1q21 a most remarkable density of genes that fulfill important functions in terminal differentiation of the human epidermis. These genes encode the cornified envelope precursors loricrin, involucrin, and small proline-rich proteins (SPRR1, SPRR2, and SPRR3), the intermediate filament-associated proteins profilaggrin and trichohyalin, and several S100A calcium-binding proteins. Extending and refining our previous physical map of 1q21 we have now mapped two additional S100A genes as well as the three SPRR subfamilies and resolved the arrangement of involucrin, SPRRs, and loricrin. All genes are linked within 1.9 Mbp of human genomic DNA in the order: S100A10, trichohyalin, profilaggrin, involucrin, SPRR3, SPRR1B, SPRR2A, loricrin, S100A9, S100A9, S100A8, S100A6. Colocalization of genes expressed late during maturation of epidermal cells together with genes encoding calcium-binding proteins is particularly intriguing since calcium levels tightly control the differentiation of epithelial cells and the expression of genes encoding epidermal structural proteins. Accounting for the close functional cooperation among these structurally and evolutionary related genes, we conclude that these loci constitute a gene complex, for which we propose the name epidermal differentiation complex.

Base Sequence↗
PubMed1996

[Mechanical/prosthetic protrusion of the mandible: effects on the pharynx].

Pharyngeal Effects: The protrusion of the mandible by prosthetic appliances ("Esmarch-prosthesis") may be a simple therapy for obstructive sleep apnea, but is effective only in rare cases. Aim of this study was the cephalometric investigation of pharyngeal changes by mechanic-/prosthetic mandibular protrusion in respect of the amount of protrusion. Cephalometric investigation was performed in 46 patients before and after mandibular protrusion, subdivided into 3 groups with protrusion of less than 7 mm, 7 to 10 mm, and more than 10 mm. A significant pharyngeal enlargement was found in all patients, but there was no correlation between the amount of protrusion and the amount of pharyngeal enlargement. Mandibular protrusion of more than 10 mm did not necessarily lead to more pharyngeal enlargement. A reliable prognosis of pharyngeal enlargement in respect of the amount of mandibular protrusion is not possible by cephalometric evaluation, even less a reliable prognosis of treatment success in respect of obstructive sleep apnea.

Adult↗
PubMed1996

[Status of radiation protection courses for physicians--plea for a change in paradigm].

The purpose of this study was to evaluate the acceptance of the statutory course of radiation protection, which is attended by physicians. As a first step towards problem based quality management, an anonymous questionnaire was used to assess the participants' opinions. The present methods in teaching, practice-orientation of the educational objectives, the prize and efficiency of the course were judged poor. Neither valid indicators of quality nor a quality management of the course exists. Facing the status quo and future demands within the medical community and society there is a serious need for reshaping radiology. It is emphasized that instead of marginal corrections only a strategic and fundamental approach to a paradigmatic reorganization will meet success.

Attitude of Health Personnel↗
PubMed1996

Sunlight and sunburn in human skin cancer: p53, apoptosis, and tumor promotion.

Sunlight is a carcinogen to which everyone is exposed. Epidemiology indicates that most carcinogenic sunlight exposure takes place several decades before the tumor arises. Some of the early events have been identified by searching for genes having ultraviolet (UV)-specific mutations. Over 90% of squamous cell carcinomas and more than 50% of basal cell carcinomas from New England patients contain UV-like mutations in the p53 tumor suppressor gene. From the mutation pattern, it can be concluded that the carcinogenic DNA lesions were pyrimidine-cytosine photoproducts caused by the UVB portion of sunlight. Particular codons of the p53 gene are most susceptible, apparently because of slower DNA repair at specific sites. Sunlight is sufficiently mutagenic often to mutate both p53 alleles. These mutations are also found in the precancer for squamous cell carcinoma, actinic keratosis, implying an early role. The function of p53 in normal skin is indicated by the observation that inactivating p53 in mouse skin reduces the appearance of sunburn cells, apoptotic keratinocytes generated by UV overexposure. Skin thus appears to possess a p53-dependent "cellular proofreading" response to DNA damage in which precancerous cells self-destruct. If this response is reduced in a single cell by a prior p53 mutation, sunburn can thereafter select for clonal expansion of the p53-mutated cell into an actinic keratosis. Sunlight appears to act twice: as tumor initiator and as tumor promoter.

Animals↗
PubMed1995

Plant histochemistry by correlation peak imaging.

Using a new NMR correlation-peak imaging technique, we were able to investigate noninvasively the spatial distribution of carbohydrates and amino acids in the hypocotyl of castor bean seedlings. In addition to the expected high sucrose concentration in the phloem area of the vascular bundles, we could also observe high levels of sucrose in the cortex parenchyma, but low levels in the pith parenchyma. In contrast, the glucose concentration was found to be lower in the cortex parenchyma than in the pith parenchyma. Glutamine and/or glutamate was detected in the cortex parenchyma and in the vascular bundles. Lysine and arginine were mainly visible in the vascular bundles, whereas valine was observed in the cortex parenchyma, but not in the vascular bundles. Although the physiological significance of these metabolite distribution patterns is not known, they demonstrate the potential of spectroscopic NMR imaging to study noninvasively the physiology and spatial metabolic heterogeneity of living plants.

Journal Article↗