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Biomedical subjects

D Müller

Publications and source records attributed to D Müller.

At least 379 records · Page 21Linked to original sources
PubMed1984

Co-transfection of normal NIH/3T3 DNA and retroval LTR sequences: a novel strategy for the detection of potential c-onc genes.

Morphologically transformed, tumorigenic cell lines were obtained after co-transfecting normal NIH/3T3 DNA and cloned 3'-long terminal repeat sequences of Moloney leukemia virus (Mo-LTR) onto NIH/3T3 recipient cells. In four such cell lines the malignant phenotype was found to be associated with single and specific Mo-LTR integration sites that were retained after serial passages through NIH/3T3 and rat 208F cells, indicating that Mo-LTR sequences are linked to the activated oncogenes. In one of these clones the activated transforming gene was identified as c-raf, the cellular homologue of a recently described retroviral oncogene. This finding not only demonstrates that the mouse c-raf gene can be activated to exhibit an oncogenic potential but also that the approach chosen in this study is suitable for the detection of potential c-onc genes. In contrast to this clone, the activated transforming genes in other cell lines appear to be different from 19 previously isolated v-onc and c-onc genes. These results demonstrate the potential of the established transformation system for the detection and isolation of previously unidentified c-onc genes.

Animals↗
PubMed1984

Differential expression of c-fos in hematopoietic cells: correlation with differentiation of monomyelocytic cells in vitro.

Among various neonatal mouse tissues, elevated levels of c-fos transcripts have been detected in crude preparations of bone. Here, we show that c-fos expression originates in the bone marrow, and to a lesser extent in adherent cells (macrophages). High levels of c-fos expression were also detected in primary cultures of differentiated bone marrow-derived macrophages, but not in cell lines resembling immature hematopoietic cells. However, when the human promyelocytic cell line HL60 was induced in vitro to differentiate into macrophages, c-fos expression was readily detectable. These findings suggest that c-fos expression in mononuclear phagocytic cells is restricted to late stages of differentiation. This pattern of c-fos expression is in marked contrast to those of the c-myb and c-myc genes which are transcriptionally active predominantly in precursor cells. In the amnion, where c-fos expression increases to high levels at late stages of gestation, synthesis of c-fos protein occurs in cells that do not resemble macrophages. It thus appears that c-fos expression in several distinct cell types is correlated with differentiation processes.

Amnion↗
PubMed1984

Multiple copies of hemolysin genes and associated sequences in the chromosomes of uropathogenic Escherichia coli strains.

The O6 serogroup Escherichia coli strain 536 carries two hemolysin (hly) determinants integrated into the chromosome. The two hly determinants are not completely identical, either functionally or structurally, as demonstrated by spontaneous deletion mutants carrying only one of them and by cloning each of the two determinants separately into cosmid vectors. Each hly determinant is independently deleted at a frequency of 10(-4), leading to variants which exhibit similar levels of internal hemolysin but different amounts of secreted hemolysin. The two hly determinants were also identified in the O4 E. coli strain 519. The three E. coli strains 251, 764, and 768, which belong to the serogroup O18, and the O4 strain 367 harbor a single chromosomal hly determinant, as demonstrated by hybridization with hly-gene-specific probes. However, a hybridization probe derived from a sequence adjacent to the hlyC-proximal end of the plasmid pHly 152-encoded hly determinant hybridizes with several additional chromosomal bands in hemolytic O18 and O6 E. coli strains and even in E. coli K-12. The size of the probe causing the multiple hybridization suggests a 1,500- to 1,800-base pair sequence directly flanking hlyC. Spontaneous hemolysin-negative mutants were isolated from strains 764 and 768, which had lost the entire hly determinant but retained all copies of the hlyC-associated sequence.2+.

Base Sequence↗
PubMed1984

The influence of cyclobarbital and diazepam on drug metabolism in vitro and their binding to cytochrome P-450.

Cyclobarbital inhibited diazepam metabolism by rat liver supernatant only at concentrations of 1 mM. Ethylmorphine N-demethylation is strongly inhibited by diazepam in a non-competitive manner whereas cyclobarbital shows a competitive inhibition type. Both cyclobarbital and oxazepam are weak inhibitors. Hexobarbital- evokes typical type I spectral changes with rat liver microsomes whereas cyclobarbital and diazepam-induced spectral changes are similar to type II or inverse type I. Barbital evoked the same type of spectral changes as diazepam and cyclobarbital. With the usual concentration in vivo the metabolism of diazepam and other drugs can scarcely be influenced by cyclobarbital.

Animals↗
PubMed1984

[Standardized morphometric studies of the right pulmonary artery in the suprasternal M-mode echocardiogram in childhood].

236 children of all age-groups, without any evidence of cardiopulmonary disease, underwent measurement of the diameters of the right pulmonary artery (RPA) in the suprasternal M-mode echocardiogram with respect to the characteristic motion pattern of the RPA. Since a high correlation was found between these diameters and height (r = 0.94; y = 1.66 square root X - 6.19), the children were divided into 9 sub-groups according to height, and mean values were calculated for all parameters in each sub-group. The systolic expansion of the RPA ranged from 18% to 30% within groups and correlated only weakly to height (r = 0.28). Suprasternal echocardiographic standards for measurement of the RPA may enhance the usefulness of this echocardiographic approach in pediatrics.

Adolescent↗
PubMed1984

[Value of early diagnosis of urinary tract infections in pregnancy].

Clinical report of severe nephrological and urological complications in pregnancy leading to the importance of early diagnosis of urinary tract infections in pregnant women. In this respect the central point is looking for asymptomatic significant bacteriuria. Microscopical methods and chemical practices are to be abandoned. The method of choice is quantitative urine culture. Early diagnosis and treatment of clinically symptomless infections in pregnancy is one of the fundamental criteria of quality in prenatal care.

Adult↗
PubMed1983

[Hepatitis and imported infectious diseases. A. Hepatitis. 1. Virologic findings in acute hepatitis].

The properties of the hepatitis-A-virus and the hepatitis-B-virus are described. The authors refer to the fact that despite the far-reaching development, particularly in the field of the hepatitis-B-infection up to a usable active immunoprophylaxis many questions concerning the natural history, pathogenesis and epidemiology are still unclarified. The development of demonstration methods of the 3rd generation and their use in the diagnostics of hepatitis rendered possible the gain of new realizations. The authors contributed to the introduction of these methods essentially by own developments, as for instance of ELISA for the demonstration of HBeAg and anti-HBe. The solution of some still open questions can be expected only by the successful establishment of a suitable virus-host-cell system.

Acute Disease↗
PubMed1983

Isolation and characterization of Chinese hamster cells defective in cell-cell coupling via gap junctions.

Chinese hamster Wg3-h-o cells which were descended from DON cells have been mutagenized and selected for derivatives defective in metabolic cooperation via gap junctions (i.e., mec-). The selection protocol included four consecutive cycles of cocultivating mutagenized cells, deficient in hypoxanthine phosphoribosyltransferase (HPRT) and wild-type cells in the presence of thioguanine (cf Slack, C, Morgan, R H M & Hooper, M L, Exp cell res 117 (1978) 195-205) [8]. We carried out the last two selection cycles in the presence of 1 mM dibutyryl cyclic adenosine monophosphate (db-cAMP). The isolated Chinese hamster CI-4 cells which expressed the mec- phenotype most stringently showed the following characteristics: 1. In standard culture medium no cell-cell coupling was detected among CI-4 cells when assayed by injections of the fluorescent dye Lucifer yellow or by electrical measurements. Between 73 and 100% of the mec+ parental cells were coupled under these conditions. Up to 14% positive contacts were found between CI-4 cells and Chinese hamster Don cells (mec+). Confluent CI-4 cells grown in the presence of 1 mM db-cAMP showed 9% coupled cells. 2. No gap junction plaques were found on electron micrographs of freeze-fractured, confluent CI-4 cells. The mec+ parental cells showed small gap junction plaques (0.013% of the total cell surface analyzed). 3. CI-4 cells exhibited 16% positive contacts and the parental Wg3-h-o cells showed 92% positive contacts in autoradiographic measurements of metabolic cooperation with DON cells. On an extracellular matrix, prepared from normal embryonic fibroblasts, metabolic cooperation between CI-4 and DON cells was autoradiographically measured to be 68%. Other cells of spontaneous mec- phenotype (for example mouse L cells or human fibrosarcoma HT1080 cells) also appeared to exhibit increased metabolic cooperation when grown on an extracellular matrix and assayed by autoradiographic measurements. When tested by Lucifer yellow injections, however, only very few positive contacts were found for CI-4/DON cell pairs and no positive contacts were found among mouse L cells grown on an extracellular matrix. 4. The mec- defect in the genome of CI-4 cells was cured in somatic cell hybrids with mouse embryonic fibroblasts or with mouse embryonal carcinoma cells. The results of isozyme and karyotype studies of mec-, as well as mec+ somatic cell hybrids suggest that mouse chromosome 16 may be involved in complementation of the mec- defect.

Animals↗
PubMed1983

Influence of impairment of the immune system on hepatic biotransformation reactions, their postnatal development and inducibility.

Neither destruction of thymus by N-methylnitrosourea or by X-rays nor thymectomy or splenectomy in rats of different ages affected hexobarbital sleeping time, ethylmorphine N-demethylation or ethoxycoumarin O-deethylation significantly and systematically. Thymectomy or thymus destruction by x-rays of newborn rats did not significantly influence postnatal development or inducibility by phenobarbital of the monooxygenase reactions.

Animals↗
PubMed1983

Relationship between plasmid and chromosomal hemolysin determinants of Escherichia coli.

Plasmid hemolysin (hly) determinants have been shown previously to comprise three cistrons (hlyA, hlyB, hlyC), coding for the synthesis and transport of hemolysin. Using recombinant plasmids as specific probes for these cistrons, we were able to analyze the chromosomal hly determinants of nine Escherichia coli strains which belonged to serotypes O4, O6, O18, and O75 and were isolated from urinary tract infections and fecal flora. The chromosomal hly genes shared extensive sequence homology with the cloned plasmid hly determinant. Nevertheless, small differences were observed, and these were found to lie mainly within cistron A (hlyA), which has been shown to determine the hemolysin protein itself. These fine variations were not specific for the O-serotype.

Base Sequence↗
PubMed1983

Transcription of c-onc genes c-rasKi and c-fms during mouse development.

We investigated the expression of cellular sequences c-rasKi and c-fms, which are homologous to the oncogenes of Kirsten rat sarcoma virus and the McDonough strain of feline sarcoma virus, during murine development and in a variety of mouse tissues. The c-rasKi gene was found to be transcribed into two mRNA species of approximately 2.0 and 4.4 kilobases, whereas a single c-fms-related transcript of approximately 3.7 kilobases was identified. The c-rasKi gene appeared to be expressed ubiquitously, since similar levels of transcripts were observed in embryos, fetuses, extraembryonal structures, and a variety of postnatal tissues. In contrast, significant expression of c-fms was found to be confined to the placenta and extraembryonal membranes (i.e., combined yolk sac and amnion). The concentration of c-fms transcripts in the placenta increased approximately 15-fold (relative to day-7 to day-9 conceptuses) during development before reaching a plateau at day 14 to 15 of gestation. The time course of cfms expression in the extraembryonal membranes appeared to parallel the stage-specific pattern observed in the placenta. The level of c-fms transcripts in the extraembryonal tissues reached a level which was approximately 20- to 50-fold greater than that in the fetus. These findings suggest that the c-fms gene product may play a role in differentiation of extraembryonal structures or in transport processes occurring in these tissues. Our results indicate that the c-onc genes analyzed in the present study exert essentially different functions during mouse development.

Animals↗