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Biomedical subjects

D Bartsch

Publications and source records attributed to D Bartsch.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Parathyroid gland cancer. Problems in diagnosis and therapy].

Parathyroid carcinoma occurs in 0.1 to 5% as the cause of primary hyperparathyroidism (HPT). It is difficult to determine the true incidence, because parathyroid carcinoma is diagnosed too often due to unreliable histologic criteria. It is only justified to make the diagnosis, when a local recurrence or metastases with the clinical picture of a recurrent or persistent HPT occurred. Treatment of choice is the initial en-bloc resection, which may result in long disease-free intervals. Pharmacological treatment, chemotherapy, and radiation are mostly ineffective in the treatment of parathyroid carcinoma. A satisfactory long-term palliation can only be achieved with repeated resections of the local recurrences and metastases. Diagnostic efforts should be made to localize the recurrent tumor before every reoperation, whereby ultrasonography of the neck is the most sensitive procedure. Occasionally the parathyroid tissue cannot be identified in spite of preoperative diagnostic studies or hypercalcemia persists after surgery. In these cases forced diuresis and medical treatment with calcitonin, diphosphonates or mithramycine can briefly control hypercalcemia. The clinical courses of 3 patients with metastasizing parathyroid carcinoma are presented and discussed. In these patients 3 to 11 surgical interventions were performed in combination with an intermittent medical treatment. By this regimen we achieved long-term palliations up to 13 years.

Adenoma↗
PubMed1992

Retinoic acid-mediated repression of human papillomavirus 18 transcription and different ligand regulation of the retinoic acid receptor beta gene in non-tumorigenic and tumorigenic HeLa hybrid cells.

Human papillomavirus type 18 (HPV18) belongs to the group of genital papillomaviruses involved in the development of cervical carcinomas. Since retinoic acid (RA) is a key regulator of epithelial cell differentiation and a growth inhibitor in vitro of HPV18-positive HeLa cervical carcinoma cells, we have used HeLa and HeLa hybrid cells in order to analyse the effects of RA on expression of the HPV18 E6 and E7 oncogenes and of the cellular RA receptor genes RAR-beta and -gamma. We show here that RA down-regulates HPV18 mRNA levels apparently due to transcriptional repression. Transient cotransfection assays indicated that RARs negatively regulate the HPV18 upstream regulatory region and that the central enhancer can confer RA-dependent repression on a heterologous promoter. RA treatment resulted in induction of RAR-beta mRNA levels in non-tumorigenic HeLa hybrid cells, but not in tumorigenic hybrid segregants nor in HeLa cells. No alterations of the RAR-beta gene or of the HeLa RAR-beta promoter could be revealed by Southern and DNA sequence analysis, respectively. As determined by transient transfection assays, however, the RAR-beta control region was activated by RA more strongly in non-tumorigenic hybrid cells than in HeLa cells, thus indicating differences in trans-acting regulatory factors. Our data suggest that the RARs are potential negative regulators of HPV18 E6 and E7 gene expression, and that dysregulation of the RAR-beta gene either causatively contributes to or is an indicator of tumorigenicity in HeLa and HeLa hybrid cells.

Base Sequence↗
PubMed1991

Influence of chromosomal integration on glucocorticoid-regulated transcription of growth-stimulating papillomavirus genes E6 and E7 in cervical carcinoma cells.

In most cervical carcinoma cells the E6 and E7 genes of specific human papillomaviruses are transcribed from viral sequences integrated into host cell chromosomes. Glucocorticoids activate the promoter elements of various human papillomaviruses in transient-expression assays. We have analyzed the effect of dexamethasone on the transcription rate of human papillomavirus 18 E6 and E7 genes integrated at different chromosomal sites in four cervical cancer cell lines. Dexamethasone led to an increase in the transcription rate of the integrated E6-E7 sequences in C4-1 and C4-2 cells but led to a decrease in SW 756 cells and did not affect the transcription rate in HeLa cells. However, when the viral promoter elements derived from HeLa or SW 756 cells, in which dexamethasone does not activate transcription of the integrated E6-E7 sequences, were tested in transient-expression assays within the same cell lines, dexamethasone consistently activated the viral promoter. It thus appears that dominant regulatory mechanisms presumably depending on the chromosomal integration site are able to override the response of the viral promoter to steroid hormones. The growth rate of all dexamethasone-treated cell lines correlated consistently with the expression of the papillomavirus E6 and E7 genes, supporting their role in the maintenance of the proliferative phenotype of cervical carcinoma cells. Since human papillomaviruses are integrated into the host cell genome at variable, presumably randomly selected chromosomal loci, regulatory mechanisms that influence viral gene expression, and hence cell growth, may differ among cancers of independent clonal origin.

Cell Line↗
PubMed1991

Distribution of the 3-fucosyl-N-acetyl-lactosamine (FAL) epitope in the adult mouse brain.

The distribution of the 3-fucosyl-N-acetyl-lactosamine (FAL) epitope within the adult mouse brain was studied by immunohistochemistry using the monoclonal antibody Leu-M1. Leu-M1-positive elements comprised astrocytes and neurons. FAL-positive astrocytes were particularly abundant in barrier structures of the brain, but were also prominent at the periphery of most medullated fiber tracts. Their intracerebral distribution led to a distinct pattern of organization, which in some locations, including the cerebral cortex, could be used for an extended regional architectonic description. Since only some FAL-positive astrocytes were also positive for glial fibrillary acid protein (GFAP), the emerging topography of the FAL-positive astrocytes often differed from the GFAP-distribution. In the cerebellum, Bergmann glia cells expressed the FAL epitope and, in the vermis, their arrangement had a band-like appearance. Positive oligodendrocytes could not be identified. The common ependymal cells were negative, whereas tanycytes were highly immunoreactive. The Leu-M1 antibody also stained some neurons. These occurred in selected neocortical regions, within the dorsal and ventral striatum, in the globus pallidus, the nucleus basalis of Meynert, the nucleus diagonalis and some hypothalamic areas. In some instances, their morphology and location indicated an association with neurochemically specified cell groups.

Animals↗
PubMed1991

Human papillomavirus type 18 E6*, E6, and E7 protein synthesis in cell-free translation systems and comparison of E6 and E7 in vitro translation products to proteins immunoprecipitated from human epithelial cells.

Expression of the E6 and E7 transforming genes of human papillomavirus type 18 (HPV18) occurs via structurally bicistronic mRNAs in which the downstream open reading frame (ORF) E7 is preceded either by the full-length ORF E6 or by a spliced ORF, E6*. We have used in vitro transcription and translation of HPV18 cDNAs in order to analyze the synthesis of E6*, E6, and E7 proteins and to compare the E6 and E7 in vitro translation products with the authentic proteins immunoprecipitated from cervical cancer cells. In wheat germ extract, in vitro translation resulted in the production of all three proteins, E6*, E6, and E7. In rabbit reticulocyte lysate, however, only the E6 and E7 proteins were produced. The lack of E6* protein was due neither to template RNA degradation nor to an inhibitory influence of the RNA 5' leader sequences, thus indicating the possibility of either inhibition of synthesis or degradation of E6* protein in reticulocyte lysate. The E7 protein was synthesized from both E6*-E7 and E6-E7 RNAs. In vitro-synthesized and authentic HPV18 E7 proteins revealed identical electrophoretic mobilities in two-dimensional gel electrophoresis, thus indicating similar modifications. By using a monoclonal antibody against the N terminus of HPV18 E6* and E6, an 18-kDa protein was detected not only in HPV18-positive but also in HPV18-negative epithelial cells. The 18-kDa proteins and the in vitro-synthesized HPV18 E6 protein exhibited comparable electrophoretic characteristics in two-dimensional gels. These results suggest the possible existence of a cellular protein related to HPV18 E6.

Cell-Free System↗
PubMed1990

Suppression in vivo of human papillomavirus type 18 E6-E7 gene expression in nontumorigenic HeLa X fibroblast hybrid cells.

The E6 and E7 genes of the cancer-associated human papillomavirus (HPV) types 16 (HPV16) and 18 (HPV18) can induce cell immortalization in vitro in normal human keratinocytes. This, however, is not associated with tumorigenicity in vivo. On the other hand, tumorigenicity of HPV18-positive HeLa cervical carcinoma cells can be suppressed by fusion of HeLa cells with normal human keratinocytes or fibroblasts. We have addressed the question of whether suppression of tumorigenicity in HeLa x fibroblast hybrid cells might be due to a reduced ability of these cells to express the HPV18 E6-E7 genes in vivo. Nontumorigenic hybrid cells and tumorigenic hybrid segregants were transplanted as organotypical cultures or injected subcutaneously into immunocompromised mice and were analyzed for HPV18 E6-E7 gene expression by RNA-RNA in situ hybridization. The tumorigenic hybrid cells showed a continuous and invasive growth that was associated with high levels of HPV18 E6-E7 mRNAs at all time points examined. In contrast, the nontumorigenic hybrid cells stopped cell proliferation approximately 3 days after transplantation. At this time they expressed the E6-E7 genes at low levels, whereas at day 2 high expression levels were observed. However, the mRNA levels of the cytoskeletal genes beta-actin and vimentin remained high for at least 14 days, demonstrating that inhibition of growth and of HPV18 E6-E7 gene expression was not due to cell death. These results suggest that growth inhibition of the nontumorigenic HeLa x fibroblast hybrid cells in vivo might be caused by suppression of HPV18 E6-E7 gene expression and are compatible with the idea of an intracellular surveillance mechanism for HPV gene expression existing in nontumorigenic cells.

Blotting, Northern↗
PubMed1988

Epstein-Barr virus nuclear antigen type 1 binding: electron microscopy.

Epstein-Barr virus (EBV) nuclear antigen type-1 (EBNA-1) was extracted and purified from Raji cells by chromatography on DNA-Sepharose and Blue-dextran Sepharose. Its complexes with plasmid pM765-10 derived from EBV (strain M-ABA) DNA were visualized by electron microscopy. The criteria of specificity were as follows: (1) preferential binding of EBNA-1 to the ori-P region of pM765-10; (2) specific enlargement of EBV DNA/EBNA-1 complexes with anti-EBNA-1 (IR-3) IgG antibody; and (3) resistance of the resulting EBV DNA/EBNA-1/anti-EBNA-1 antibody complexes to treatment with 1.5 M NaCl. The optimal conditions for the formation of EBV DNA/EBNA-1 complexes were 50 to 150 mM NaCl and pH 6.0. A balanced equilibrium of EBNA-1 and pM765-10 was necessary to achieve both a high yield and specificity of EBV DNA/EBNA-1 complexes.

Antigens, Viral↗
PubMed1987

Electron microscopy of binding of Epstein-Barr virus (EBV) nuclear antigen (EBNA-1) to EBV DNA.

Specific binding sites for Epstein-Barr virus (EBV) nuclear antigen (EBNA-1), isolated and semipurified from EBV-transformed nonproductive Raji cells, were visualized on the molecule of EBV DNA by electron microscopy and mapped. Two measures had to be applied to counteract the limited purity of the EBNA-1 preparation: (i) EBV DNA/EBNA-1 complexes were specifically enlarged by binding with anti-EBNA-1 (IR-3) IgG antibody. (ii) DNA-binding proteins that did not react with the anti-EBNA-1 antibody were eluted from EBV DNA with 1.5 M NaCl, taking advantage of the resistance of DNA/EBNA-1/anti-EBNA-1 antibody complexes to the high-salt treatment. EBNA-1 bound at the highest relative frequency (greater than 30%) to the EBV DNA map positions of 8.8 +/- 0.3, 10.3 +/- 0.5, and 46.6 +/- 1.2 kb. It bound with a lower but still statistically significant frequency (16%) to the map positions of 64.5 +/- 1.0, 89.7 +/- 1.6, 129.6 +/- 1.1 kb.

Antigens, Viral↗
PubMed1987

Transfection of human lymphocytes with cloned Epstein-Barr virus (EBV) DNA.

Human primary cord-blood lymphocytes were transfected, using the DEAE-dextran technique, with a set of seven largely overlapping clones jointly covering the whole M-ABA Epstein-Barr virus (EBV) genome. Three fragments, cosmids cMB-14 and cM301-99 and plasmid pM966-20, were able to stimulate transient cellular DNA synthesis, blastic transformation, and clumps formation, as well as to prolong the life span from a maximum of 2 weeks in control cultures to up to 6 weeks. The fragments stimulating DNA synthesis also expressed this property in mutual combinations or when combined with cosmid cMSal-A or cM302-21. Their use with any other fragments in cotransfection did not result in further DNA synthesis stimulation. Cosmids cM302-23 and cMSal-B suppressed this effect. Cosmid cM301-99 but not cM302-23 induced transient EBNA-1 formation in about 1% of lymphocytes. Lymphocytes transfected with single fragments or their combinations failed to grow into immortalized cell lines. The results suggest that transient expression of viral functions at levels achievable by transfection is not sufficient for cell immortalization.

Cell Transformation, Viral↗
PubMed1983

[Experimental development of hollow cellulose membranes for blood detoxification].

In recent years there have been repeated demands in medical circles for new membranes for various purposes. At present attention is focussed on the development of membranes for the detoxification of blood. Using available technology and resources, it seemed appropriate to develop such hollow membranes out of cellulose by the viscose process. It is possible to give the membrane a suitable structure according to the use intended. The transport of matter and ultrafiltration can be influenced by varying the influence parameter in the spinning process via changes in the pore structure. In this way it is possible to produce hollow membranes for dialysis or ultrafiltration, with varying grades of permeability, out of cellulose by the viscose process.

Blood↗
PubMed1976

[Rheology and spinning of alkaline solutions of sunflower seed globulin and casein].

The specific demand of sodium hydroxide is determined for the dissolution of sunflower seed globulin, casein and a mixture of them to equal parts. In low protein-containing solutions it depends for sunflower seed globulin very much on the sodium chloride concentration. From sunflower seed globulin, casein and a mixture of them to equal parts are prepared with sodium hydroxide high protein-containing alkaline solutions. Sunflower seed globulin forms temporally a gel phase. After this phase the solution of sunflower seed globulin shows like casein and a mixture of sunflower seed globulin/casein (I:I) pseudoplastic flow. The flow curves of the pseudoplastic solutions are described mathematically with the OSWALDian power statement. By alkaline solutions of casein and sunflower seed globulin/casein (I:I) the flow exponent n is distributed statistically about 0.9, by solutions of sunflower seed globulin a distribution exists about the mean values n = 0.85 and n = 0.50. lg k depends in all protein solutions on the concentration of protein, sodium chloride, sodium hydroxide and on the temperature and time. For all protein solutions exists a linear relation between the logarithm of viscosity and the reciprocal temperature for lg k and I/T, which is derived normally for NEWTONian flow behaviour. In a suitable scope of spinning for all protein solutions are carried out complete factorial experiment, which guide to regression equations of lg k; in the case of sunflower seed globulin are calculated also a regression equation of the flow exponent n. Going out from the parameters of the spinning process the properties of the spun sunflower seed globulin/casein (I:I) fibers are described.

Caseins↗
PubMed1976

[Rheology and spinning of alkaline solution of field bean protein and casein].

From field bean protein and a mixture of field bean protein with casein to equal parts are prepared with sodium hydroxide high protein-containing alkaline solutions, which show pseudoplastic flow. The flow curves of the pseudoplastic field bean protein-casein (I:I)-solutions are described mathematically with the Ostwaldian power statement. In a suitable scope of spinning of this solutions are carried out complete factorial experiments, which guide to regression equations of lg k and n. g k depends on the concentration of protein; an effect of the sodium hydroxide concentration exists lonly about interactions. On the other hand the flow exponent n depends on the hydroxide concentration. The properties of the spun field bean protein/casein (I:I) fibres are described.

Caseins↗
PubMed1976

[Characterization and spinning of alkaline solutions of wheat protein and casein].

The viscosity behaviour of alkaline solutions of mixtures from different wheat glutens with casein in dependence on the concentration of the whole protein, wheat protein, sodium hydroxide, sodium chloride and on the temperature, time and the effect of treatment of wet wheat gluten with sodium chloride or sodium hydroxide on the properties of the spun wheat protein/casein fibers are described. Based on this model experiments the rheological behaviour of alkaline solutions of wheat protein/casein (I:2) and proceed from the parameters of the spinning process the properties of the corresponding spun fibers are represented.

Caseins↗