Biomedical subjects

M Schmid

Publications and source records attributed to M Schmid.

At least 217 records · Page 12Linked to original sources

PubMed1998

[Therapy studies of the Austrian Breast Cancer Group (ABC)].

The Austrian Breast Cancer Group (ABC) consisting of more than 60 participating centers in Austria has randomized more than 5800 patients in 11 randomized trials since 1984. At present, roughly 30% of all patients with the diagnosis primary breast cancer are accrued in protocols throughout the country. Due to specific activities, the breast conservation rate raised from an initial 20% to more than 60% in the last years. Multicenter trials are not only the basis for progress in medicine but also tools for quality control and quality improvement.

Antineoplastic Agents, Hormonal↗

PubMed1997

Identification of dynein heavy chain genes expressed in human and mouse testis: chromosomal localization of an axonemal dynein gene.

Dynein heavy chains are involved in microtubule-dependent transport processes. While cytoplasmic dyneins are involved in chromosome or vesicle movement, axonemal dyneins are essential for motility of cilia and flagella. Here we report the isolation of dynein heavy chain (DHC)-like sequences in man and mouse. Using polymerase chain reaction and reverse-transcribed human and mouse testis RNA cDNA fragments encoding the conserved ATP binding region of dynein heavy chains were amplified. We identified 11 different mouse and eight human dynein-like sequences in testis which show high similarity to known dyneins of different species such as rat, sea urchin or green algae. Sequence similarities suggest that two of the mouse clones and one human clone encode putative cytoplasmic dynein heavy chains, whereas the other sequences show higher similarity to axonemal dyneins. Two of nine axonemal dynein isoforms identified in the mouse testis are more closely related to known outer arm dyneins, while seven clones seem to belong to the inner arm dynein group. Of the isolated human isoforms three clones were classified as outer arm and four clones as inner arm dynein heavy chains. Each of the DHC cDNAs corresponds to an individual gene as determined by Southern blot experiments. The alignment of the deduced protein sequences between human (HDHC) and mouse (MDHC) dynein fragments reveals higher similarity between single human and mouse sequences than between two sequences of the same species. Human and mouse cDNA fragments were used to isolate genomic clones. Two of these clones, gHDHC7 and gMDHC7, are homologous genes encoding axonemal inner arm dyneins. While the human clone is assigned to 3p21, the mouse gene maps to chromosome 14.

Amino Acid Sequence↗

PubMed1997

Susceptibility to the development of pigment cell tumors in a clone of the Amazon molly, Poecilia formosa, introduced through a microchromosome.

The Amazon molly Poecilia formosa is a gynogenetic fish that reproduces through the development of ameiotic diploid eggs triggered by insemination by males of related species without following karyogamie. This leads to clonal offspring. In rare cases, however, this gynogenesis is leaky, and paternal DNA in the form of small supernumerary chromosomes is included into the maternal genome. We have obtained a clone where one such microchromosome contains a pigmentary locus, resulting in macromelanophore pigmentation of the carrier. Approximately 5% of these fish spontaneously develop exophytic nodular or papillomatous pigment cell tumors. The tumors display considerable differences with respect to growth characteristics and invasiveness, despite the genetic uniformity of the affected animals. Following transplantation to syngeneic hosts, a remarkable clonal variability was observed. Oncogenes that are involved in tumorigenesis in hereditary melanoma of the closely related fish Xiphophorus appear not to be instrumental for induction of the P. formosa pigment cell tumors. Moreover, a new genetic locus is defined that mediates susceptibility to pigment cell tumor development and leads to transformation of chromatoblasts.

Animals↗

PubMed1997

CD68+ cells of monocyte/macrophage lineage in the environment of AIDS-associated and classic-sporadic Kaposi sarcoma are singly or doubly infected with human herpesviruses 7 and 6B.

Earlier studies have shown that Kaposi sarcomas contain cells infected with human herpesvirus (HHV) 6B, and in current studies we report that both AIDS-associated and classic-sporadic Kaposi sarcoma contain HHV-7 genome sequences detectable by PCR. To determine the distribution of HHV-7-infected cells relative to those infected with HHV-6, sections from paraffin-embedded tissues were allowed to react with antibodies to HHV-7 virion tegument phosphoprotein pp85 and to HHV-6B protein p101. The antibodies are specific for HHV-7 and HHV-6B, respectively, and they retained reactivity for antigens contained in formalin-fixed, paraffin-embedded tissue samples. We report that (i) HHV-7 pp85 was present in 9 of 32 AIDS-associated Kaposi sarcomas, and in 1 of 7 classical-sporadic HIV-negative Kaposi sarcomas; (ii) HHV-7 pp85 was detected primarily in cells bearing the CD68 marker characteristic of the monocyte/macrophage lineage present in or surrounding the Kaposi sarcoma lesions; and (iii) in a number of Kaposi sarcoma specimens, tumor-associated CD68+ monocytes/macrophages expressed simultaneously antigens from both HHV-7 and HHV-6B, and therefore appeared to be doubly infected with the two viruses. CD68+ monocytes/macrophages infected with HHV-7 were readily detectable in Kaposi sarcoma, but virtually absent from other normal or pathological tissues that harbor macrophages. Because all of the available data indicate that HHV-7 infects CD4+ T lymphocytes, these results suggest that the environment of the Kaposi sarcoma (i) attracts circulating peripheral lymphocytes and monocytes, triggers the replication of latent viruses, and thereby increases the local concentration of viruses, (ii) renders CD68+ monocytes/macrophages susceptible to infection with HHV-7, and (iii) the combination of both events enables double infections of cells with both HHV-6B and HHV-7.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Altered sensitivity to retinoid-induced apoptosis associated with changes in the subcellular distribution of Bcl-2.

In the acute promyelocytic leukemia cell line NB4, Bcl-2 downregulation occurred as a late event of retinoid-induced differentiation. In the maturation-resistant NB4-R1 subclone, retinoids failed to downregulate Bcl-2 even in the situation of apoptosis massively induced by pan-agonists and RXR-selective agonists. We observed that NB4 and NB4-R1 cells differed with respect to the intracellular localization of Bcl-2 which showed a perinuclear localization in NB4-R1 cells, while Bax was broadly expressed in the cytoplasm and to only a minor extent in the perinuclear area. Therefore, the distinct intracellular localization of Bcl-2 and Bax was in general nonoverlapping. Bcl-2 remained massively expressed until cell disruption. Bax was not significantly upregulated in cells committed to death. However, Bax localization changed from a diffuse pattern to concentrate in few specific cytoplasmic area at a stage preceding the formation of apoptotic bodies. A human Bcl-2 transgene was transiently overexpressed in NB4-R1 cells which showed increased resistance to apoptosis induced by retinoids. Stably transfected clones of NB4-R1 cells showed an increased expression of Bcl-2 and a marked resistance to apoptosis. Interestingly, the overexpression of Bcl-2 restored a pattern of uniform Bcl-2 labeling in the cytoplasm and, remarkably, the colocalization of Bcl-2 with Bax. This work demonstrates that the ability of retinoid-induced cells to undergo apoptosis depends on the level of expression and the functional interaction between Bcl-2 and Bax.

Apoptosis↗

PubMed1997

Structure of the human type I iodothyronine 5'-deiodinase gene and localization to chromosome 1p32-p33.

The human type I iodothyronine 5'-deiodinase gene encodes a member of the family of selenocysteine-containing deiodinases. These enzymes catalyze the activation of the prohormone thyroxine to 3,3',5-triiodothyronine or the degradation of thyroxine and triiodothyronine to inactive metabolites. Here we report the isolation of two genomic type I 5'-deiodinase clones from a chromosome 1-specific gridded cosmid library, the localization of the gene to chromosome 1p32-p33 by fluorescence in situ hybridization, and the determination of the complete structure of the 17.5-kb gene.

Base Sequence↗

PubMed1997

Sequence of a gene cluster from Klebsiella pneumoniae encoding malonate decarboxylase and expression of the enzyme in Escherichia coli.

Malonate decarboxylase of Klebsiella pneumoniae consists of four different subunits and catalyzes the conversion of malonate plus H+ to acetate and CO2. The catalysis proceeds via acetyl and malonyl thioester residues with the phosphribosyl-dephospho-CoA prosthetic group of the acyl carrier protein (ACP) subunit. From a cosmid library of K. pneumoniae, a gene cluster of 9 kb has been isolated and sequenced that included the structural genes for the malonate decarboxylase. The cluster consisted of the eight consecutive genes mdcABCDEFGH and the divergently oriented mdcR gene. The intergenic regions were short (usually < 17 bp, 136 bp between mdcE and mdcF) and ribosome binding sites were found 4-10 bp before each gene. According to N-terminal protein sequencing, the mdcA, C, D and E genes encoded subunits alpha, delta, beta and gamma of malonate decarboxylase. Data bank searches for related proteins with known function revealed that MdcA represents the ACP-transferase and that MdcD and E together probably function as malonyl-S-ACP decarboxylase. MdcC is the (apo) ACP subunit. MdcB and MdcG could be involved in the synthesis and attachment of the prosthetic group. MdcH is similar to various malonyl-CoA:ACP-SH transacylases and therefore probably involved in the initial activation of the enzyme by malonylation. MdcF is a membrane protein that could function as a malonate carrier. The mdcR gene encodes a protein of the LysR regulator family. Malonate decarboxylase was functionally expressed in Escherichia coli from plasmids harbouring the entire gene cluster including mdcR. As partial deletion of the mdcR gene impaired growth of the transformants on malonate, MdcR is probably a transcriptional regulator of the mdc genes.

Amino Acid Sequence↗

PubMed1997

p53 abnormalities are rare events in neuroendocrine (Merkel cell) carcinoma of the skin. An immunohistochemical and SSCP analysis.

The aim of the present study was to assess a possible role of the tumour suppressor gene p53 in neuroendocrine (Merkel cell) carcinoma of the skin with regard to tumour development and tumour progression. p53 was investigated in a series of routinely processed Merkel cell carcinomas, with application of four different p53 antibodies (CM-1, PAb1801, DO7, and PAb240) to 25 carcinomas and screening for p53 mutations of exons 4-8 by single-strand conformation polymorphism (SSCP) analysis in 9 cases. All 25 tumours in the present series showed the characteristic microscopic and immunohistochemical features of Merkel cell carcinoma of the skin. In 5 of the 25 Merkel cell carcinomas investigated 5-10% of tumour cell nuclei showed a positive p53 reaction with at least one anti-p53 antibody. A few scattered p53 positive nuclei were found in an additional 9 cases. The remaining 11 cases completely lacked p53 immunostaining. SSCP analysis of exons 4-8 revealed no significant alterations in the mobility shift of the single strand DNAs in the five cases with 5-10% p53-immunoreactive tumour nuclei or in five cases lacking p53 accumulation significant. Our results suggest that alterations of the p53 gene play only a minor part in the development or progression of Merkel cell carcinoma of the skin.

Aged↗

PubMed1997

Cloning of the homogentisate 1,2-dioxygenase gene, the key enzyme of alkaptonuria in mouse.

We determined 48 amino acid residues from five peptides from the homogeneous monomer of homogentisate 1,2-dioxygenase (HGO; E.C. 1.13. 11.15) of mouse liver. After digestion with trypsin, peptides were separated by reversed phase chromatography and amino acid sequenced. The deduced codon sequence of three peptides was used to derive degenerated oligomeres. By combining these oligos, we were able to amplify fragments from 100 to 300 bases (b) from mouse liver cDNA by polymerase chain reaction after reverse transcription (RT-PCR). A fragment of 200 b was cloned and used as a probe to screen a mouse liver cDNA library. One clone from this library contained the complete cDNA-insert for HGO as determined by sequencing. The cDNA encodes for a protein of 50 kDa, as predicted. The cDNA of mouse HGO has an overall identity of 41% to the corresponding gene hmgA from Aspergillus. Sequence similarities to human expressed sequence tags (EST) clones ranged from 70% to 20%. The positions of 122 conserved amino acids could be determined by multiple sequence alignment. We identified one first intron of 928 b in the mouse gene. The gene for HGO seems to be expressed in various tissues, as shown by RT-PCR on different cDNAs. FISH experiments with the whole murine cDNA as probe clearly revealed signals at the human chromosomal band 3q13. 3-q21. This corresponds well to the previous assignment of the locus for the human alkaptonuria gene (AKU) to the same chromosomal region by multipoint linkage analysis. We therefore conclude that the HGO cDNA encodes the gene responsible for alkaptonuria.

Alkaptonuria↗

PubMed1997

Segregation of sex chromosomes into sperm nuclei in a man with 47,XXY Klinefelter's karyotype: a FISH analysis.

Meiotic segregation of the sex chromosomes was analysed in sperm nuclei from a man with Klinefelter's karyotype by three-colour FISH. The X- and Y-specific DNA probes were co-hybridized with a probe specific for chromosome 1, thus allowing diploid and hyperhaploid spermatozoa to be distinguished. A total of 2206 sperm nuclei was examined; 958 cells contained an X chromosome, 1077 a Y chromosome. The ratio of X:Y bearing sperm differed significantly from the expected 1:1 ratio (chi2 = 6.96; 0.001 < P < 0.01). Sex-chromosomal hyperhaploidy was detected in 2.67% of the cells (1.22% XX, 1.36% XY, 0.09% YY) and a diploid constitution in 0.23%. Although the frequency of 24,YY sperm was similar to that detected in fertile males, the frequencies of 24,XX, 24,XY and diploid cells were significantly increased. A sex-chromosomal signal was missing in 4.26% of the spermatozoa. This percentage appeared to be too high to be attributed merely to nullisomy for the sex chromosomes and was considered, at least partially, to be the result of superposition of sex-chromosomal hybridization signals by autosomal signals in a number of sperm nuclei. The results contribute additional evidence that 47,XXY cells are able to complete meiosis and produce mature sperm nuclei.

Adult↗

PubMed1997

Analysis of structural and numerical chromosome abnormalities in sperm of normal men and carriers of constitutional chromosome aberrations. A review.

Sperm chromosome analysis offers the opportunity to gather information about the origin of chromosome aberrations in human germ cells. Over the last 20 years more than 20,000 sperm chromosome complements from normal donors and almost 6000 spermatozoa from men with constitutional chromosome aberrations (inversions, translocations) have been analyzed for structural and numerical chromosome abnormalities, as well as for segregation of the constitutional chromosome aberrations after the sperm had penetrated hamster oocytes. On the other hand, it took only 6 years to screen more than 3 million mature spermatozoa from healthy probands for disomy rates of 20 autosomes (chromosomes 19 and 22 not evaluated) and the sex chromosomes, and for diploidy rates by in situ hybridization techniques. In the present paper the results arising from both methods are compiled and compared.

Adult↗

PubMed1997

Pregnancy after intracytoplasmic sperm injection with sperm from a man with a 47,XXY Klinefelter's karyotype.

OBJECTIVE: To report the initiation of a pregnancy that was achieved by intracytoplasmic sperm injection (ICSI) with sperm from a patient with Klinefelter's syndrome. DESIGN: Case report. SETTING: University women's hospital IVF center. PATIENT(S): A couple with primary infertility and nonmosaic 47,XXY karyotype of the male partner. INTERVENTION(S): Intracytoplasmic sperm injection after ovarian stimulation and transvaginal ultrasound-guided oocyte pick-up with sperm from a hypergonadotropic man with a nonmosaic 47,XXY karyotype. MAIN OUTCOME MEASURE(S): Clinical pregnancy. RESULT(S): Despite a 47,XXY karyotype in all 50 analyzed lymphocyte metaphases, the sperm of the patient led to a clinical pregnancy with the first attempt of ICSI and intrauterine transfer of three embryos. The pregnancy stopped developing in the ninth week. Cytogenetic investigation of the abortion material revealed a numerical normal 46,XXY karyotype. CONCLUSION(S): Sperm from a patient with hypergonadotropic nonmosaic Klinefelter's syndrome, when used for ICSI, can lead to a pregnancy.

Abortion, Induced↗

PubMed1997

Cytogenetics of the genus Leporinus (Pisces, Anostomidae). 1. Karyotype analysis, heterochromatin distribution and sex chromosomes.

Cytogenetic analyses (Giemsa staining, C-banding, AgNO3 labelling of nucleolus organizer regions (NORs) and staining with base-specific fluorochromes) were performed on the South American fish species Leporinus friderici, L. obtusidens and L. elongatus. The overall karyotypic structure, position of NORs, as well as the amount, distribution and composition of constitutive heterochromatin were determined. Particular attention was given to the highly differentiated ZZ/ZW sex chromosome system of L. obtusidens and L. elongatus. Sharing the apparently ancient macroscopic karyotype of Anostomidae, all three species have 2n = 54 meta- or submetacentric chromosomes. NORs were found exclusively on chromosome pair 2, which may represent the ancestral NOR-bearing chromosome of the anostomid karyotype. Observed differences in the relative position of NORs along chromosome 2 and variations in the amount and distribution of constitutive heterochromatin throughout the karyotype were most probably caused by heterochromatin-mediated chromosome rearrangements. Detailed analysis of the morphologically similar heteromorphic ZZ/ZW sex chromosomes of L. obtusidens and L. elongatus allowed detection of differences in the DNA composition of the largely heterochromatic W chromosomes. However, since these and the W chromosomes of three other Leporinus species exhibit homologies with respect to their relative size, centromere position and amount and distribution of heterochromatin, it is concluded that they evolved from the same ancestral W chromosome.

Animals↗

PubMed1997

Cytogenetics of the genus Leporinus (Pisces, Anostomidae). II. Molecular cytogenetics, organization and evolutionary conservation of a chromosome-specific satellite DNA from Leporinus obtusidens.

A chromosome-specific satellite DNA from the South American fish species Leporinus obtusidens has been isolated and characterized. Sequence analysis and Southern hybridization studies indicate that the cloned 483-bp fragment is 60% AT rich and appears to comprise two diverged monomers. A highly variable low-copy number polymorphism was detected and, thus, this satellite DNA may serve as a valuable genetic marker. Using a Southern blot approach, the cloned satellite DNA cross-hybridized strongly to the DNA of Leporinus elongatus but failed to detect homologous sequences in the genomes of other closely related Leporinus species and higher vertebrates. Using fluorescence in situ hybridization to mitotic metaphase spreads of L. obtusidens and L. elongatus, this satellite DNA was located to the (peri)centromeric region of one single chromosome pair in both species. As the cloned satellite DNA sequence clearly evolved along a chromosomal lineage and is highly variable, it may serve as a very useful marker in further genetic, molecular and cytogenetic studies of the genus Leporinus.

Animals↗

PubMed1997

Polymorphism of the tumour necrosis factor-alpha and lymphotoxin-alpha genes in hairy cell leukaemia.

Hairy cell leukaemia (HCL) is a rare chronic B lymphoproliferative disorder which can lead to severe pancytopenia and several immunologic abnormalities. The pathogenetic role of tumour necrosis factor (TNF)-alpha in HCL prompted us to study the potential contribution of functionally important genetic polymorphisms of the TNF gene cluster in a large group of patients with HCL. The TNF-alpha (-308 bp) promoter/enhancer point mutation and two polymorphisms located within the first intron of the lymphotoxin (LT)-alpha gene showed neither significant allelic deviation for the patient group nor, after analysis of clinical characteristics such as blood counts, stable or progressive disease or response to therapy.

Adult↗

PubMed1997

Polymorphism of the tumour necrosis factor-alpha and lymphotoxin-alpha genes in chronic lymphocytic leukaemia.

The neoplastic cells of CLL are able to produce TNF which is known to stimulate the proliferation of CLL cells in an autocrine and paracrine manner. Genetic polymorphism of molecules of the TNF ligand superfamily has been described and certain alleles were suspected to predispose to variant biological responses. Previously, the rare allele TNFB*1 of the TNF-beta/lymphotoxin (LT)-alpha gene (NcoI, asparagine at amino acid position 26) was found to be associated with a stronger LT-alpha response of PBMC in vitro. We now report on a significant increase of the allele TNF1 (TNFA -308 G) of the TNF-alpha promoter/enhancer polymorphism in a group of 73 CLL patients when compared to healthy individuals (RR = 3.18, 95% confidence interval 1.57-8.3; P = 0.006). The allelic distribution of the TNF-beta/LT-alpha NcoI polymorphism did not differ significantly from randomized healthy controls. On the other hand, the frequency of the allele TNFB*2 was increased in CLL patients with advanced clinical stage (P = 0.004). These findings indicate immunogenetic associations involving polymorphisms of cytokine genes serving as paracrine and autocrine growth factors, which thus can contribute to the pathogenesis of the TNF/LT-sensitive haematological malignancy CLL.

Adult↗

PubMed1997

Follow-up in children with Joubert syndrome.

Although Joubert syndrome (JS) was first reported in 1969 by Joubert et al (21), the long-term outcome is not yet documented. We report 19 children (4 pairs of siblings) from a single institution diagnosed with JS. Nine children were last seen between ages 10 and 18 years, seven between ages 1 and 4 years. Three children died before 3 years of age, showing marked breathing problems and minimal development. The 16 surviving children showed variable motor development, walking was typically achieved between 2 and 10 years, two children did not learn to walk. Cognitive development showed four with development quotient (DQ) of 30 or less and nine with DQ of 60-85, the others could not be judged confidently. Siblings did not show similar development and sex was not predicting outcome. The following oculomotor problems were seen: mystagmus in 11, ocular motor apraxia in six, isolated ptosis in two, and vertical gaze palsy in three. Additional features were retinal involvement in eight and kidney involvement in four, in one of them after normal previous ultrasound. In conclusion development of children with JS can be split into distinct subgroups, with one group dying at a young age. Those who survive show variable motor and cognitive development and can be grouped into those with DQ of less than 30 or those with DQ between 60 and 85. Ophthalmological and renal involvement may change or develop over the years and should be followed carefully.

Adolescent↗

PubMed1997

Controlling varicella in the healthcare setting: the cost effectiveness of using varicella vaccine in healthcare workers.

OBJECTIVE: To determine if varicella vaccination of healthcare workers would result in a net cost savings. DESIGN: A Markov-based decision analysis. SETTING: The analysis was based on a hypothetical population of healthcare workers. Data were obtained from exposure records of a tertiary-care hospital and from the literature. Workers were considered potentially susceptible if they had no past history of varicella. RESULTS: Vaccination of potentially susceptible workers would result in a net cost savings of $59 per person. Serological testing prior to vaccination resulted in smaller net savings. The results were robust across a wide range of assumptions. Importantly, however, the result was very dependent on infection control policy regarding work restrictions for vaccine recipients. If more than 3% of vaccinees were removed from work due to vaccine-associated rash, vaccination no longer would result in a net cost savings. CONCLUSION: Varicella vaccination of potentially susceptible healthcare workers can reduce costs and decrease morbidity. Infection control policy regarding work restrictions for vaccine recipients will play a key role in the feasibility of vaccination.

Chickenpox↗