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R Reichel

Publications and source records attributed to R Reichel.

32 records · Page 2Linked to original sources
PubMed1987

Role of an adenovirus E2 promoter binding factor in E1A-mediated coordinate gene control.

A product of the adenovirus gene E1A is responsible for the stimulation of transcription from six viral promoters as well as at least two cellular promoters. We have detected a HeLa cell factor, termed E2 promoter binding factor (E2F), that appears to mediate the transcriptional stimulation of the viral E2 promoter. Competition experiments revealed that E2F did not recognize and bind to the E1B, E3, E4, or major late promoter sequences. Furthermore, three additional promoters stimulated by E1A, heat shock protein 70, beta-globin, and early simian virus 40, do not bind E2F. In contrast, the factor does recognize sequences in the E1A enhancer, and within the E1A enhancer are duplicated binding sites for E2F. Finally, a single E2F binding site from the E1A enhancer can confer increased transcription to a mouse beta-globin promoter, dependent on the action of the E1A gene product. This stimulation requires binding of E2F since methylation of the binding site, which blocks binding in vitro, reduces transcription stimulation in vivo. We, therefore, conclude that E2F is likely to be responsible for the E1A-mediated stimulation of the E1A gene as well as the E2 gene but is not involved in the activation of the other E1A-inducible promoters.

Adenovirus Early Proteins↗
PubMed1986

Identification of a cellular transcription factor involved in E1A trans-activation.

We have employed a gel assay to detect a transcription factor in nuclear extracts of adenovirus-infected cells that interacts with the adenovirus E2 promoter, an E1A inducible promoter. Binding of the factor to the promoter protected sequences between -33 and -74 from DNAase cleavage in a footprint assay. This region was also protected from exonuclease III digestion. These sequences coincide with those previously shown to be essential for promoter activity and E1A stimulation. The factor could be detected in extracts of uninfected cells, although at greatly reduced levels. The increased level of factor in infected cells required a functional E1A gene. These results suggest that the E2 binding activity is a cellular transcriptional factor, the concentration or binding activity of which increases as a result of the action of the E1A gene product.

Adenovirus Early Proteins↗
PubMed1986

E1A transcription induction: enhanced binding of a factor to upstream promoter sequences.

The adenovirus E1A gene product trans-activates a number of viral and cellular promoters. The mechanism for this transcriptional induction was investigated with an in vivo exoIII mapping technique to assay for proteins that interact with an E1A-inducible promoter. A protein bound to the early E2 promoter was detected in wild-type infected cells. In the absence of E1A induction, specific interactions at the promoter could not be detected, as indicated by the absence of an exoIII-protected fragment. However, if conditions were established that allowed transcription of the E2 gene in the absence of E1A, the same exoIII protection was observed as was found in the presence of E1A. These results suggest a model in which the efficient utilization of the E2 promoter is mediated by a cellular transcription factor. In the absence of E1A, the interaction can take place, but slowly and inefficiently in comparison with the interaction in the presence of E1A.

Adenovirus Early Proteins↗
PubMed1985

[Resorption of prostaglandin E2 following various methods of local administration for ripening of the cervix and end the induction of labor].

PGEM concentration was determined radioimmunologically in a non-pregnant woman in whom PGE2 was infused intravenously at increasing dosage and in women in whom labour was induced by various methods for local application of PGE2. There was excellent correlation between the amount of PGE2 infused intravenously and the levels of PGEM determined in the peripheral plasma. The following methods of local application of PGE2 were included in the study: 0.4 mg PGE2 gel placed retroamnially by means of a balloon catheter; 0.4 and 0.5 mg PGE2 gel applied endocervically; 1.5 mg PGE2 given pericervically through a portio adapter and 3 mg PGE2 placed intravaginally in form of a single vaginal tablet; also included was a control group where only vaginal examination was performed. Blood was withdrawn before, and then 30 minutes, 1, 2 and 3 hours after PGE2 administration. Mean levels of PGEM in the maternal peripheral plasma showed no change within or between the various groups, with the exception of one patient in the portio adapter group where hyperstimulation occurred. After removal of the adapter PGEM levels dropped to baseline values. It is concluded from the present study that local application of doses currently used to soften the cervix and/or induce labour at term does not give rise to PGEM concentrations in the maternal blood of the same magnitude as achieved by intravenous PGE2 administration.

Abortion, Induced↗
PubMed1984

Localization of small nuclear polymerase I RNA sequences at the 5' end of the human rDNA transcription unit.

A human ribosomal DNA clone isolated from a genomic library was used to localize the DNA sequences coding for HeLa cell small nuclear polymerase I RNA (snPI RNA). By using a subcloned 1.2-kb EcoRI-SalI fragment, including the initiation region of the 45S rRNA transcription unit, it was shown that the snPI RNA sequences are located within the first 600 nucleotides of the 5' end of the external transcribed spacer. Strand-specific hybridization following exonuclease III digestion of the plasmid containing the 1.2-kb Eco-Sal fragment demonstrated that the snPI RNA molecules and the 45S pre-rRNA are transcribed from the same coding strand. A detailed mapping of individual snPI RNA molecules showed that most of these small RNA species span the putative early processing site at position 415 of the external transcribed spacer of the human rRNA precursor.

Base Sequence↗
PubMed1984

Plasma concentration of 13,14-dihydro-15-keto-PGE2 (PGEM) after various ways of cervix ripening with PGE2.

PGEM concentration was determined radioimmunologically in a non-pregnant woman, in whom PGE2 was infused intravenously at increasing rates and in women, in whom labor was induced by various methods for local application of PGE2. There was excellent correlation between the amount of PGE2 infused intravenously and the levels of PGEM determined in the peripheral plasma. The following methods of local application of PGE2 were included in the study: 0.4 mg PGE2 gel placed retroamnially by means of a balloon catheter, 0.4 and 0.5 mg PGE2 applied endocervically and 3 mg PGE2 placed intravaginally in form of a single vaginal tablet; also included was a control-group, where only vaginal examination was performed. Bloods were drawn before, 30 minutes, 1, 2 and 3 hours after PGE2 administration. Mean levels of PGEM in the maternal peripheral plasma did not change neither within nor between the various groups. It is concluded from the present study, that local application of doses currently used to soften the cervix and/or induce labor at term do not lead to the same PGEM-concentration in the maternal blood as after intravenous infusion of PGE2 in doses normally used to induce labor.

Cervix Uteri↗
PubMed1983

Isolation and characterization of snRNA and scRNA gene candidates from a human genomic library.

A simple procedure for the isolation and preparative gel electrophoresis of snRNA and scRNA is described. These small RNA species were used to select DNA sequences from a human genomic library which are able to protect hybridized snRNA or scRNA against T1-ribonuclease attack. The snRNA clones obtained contain only sequences for one snRNA species and only one copy of the respective gene. In contrast, more than one 7S RNA gene is present within the scRNA clones.

Cloning, Molecular↗
PubMed1982

Small nuclear RNAs are encoded in the nontranscribed region of ribosomal spacer DNA.

The structure of in vitro synthesized mouse small nuclear RNA transcribed by RNA polymerase I (snPI RNA) was studied by T1 RNase digestion pattern analysis. The patterns of four different snPI RNA species were different from those of the U1 and U2 RNA species. In addition, the four different snPI RNA species, ranging from 130 to 240 nucleotides in length, yielded almost identical patterns. The snPI RNA molecules hybridized to cloned mouse ribosomal DNA containing the nontranscribed spacer DNA and 45S ribosomal precursor RNA molecules did not compete with this hybridization. Southern blot analysis of fragments from the ribosomal DNA confirmed that snPI RNA species exclusively hybridized to sequences corresponding to the so-called nontranscribed ribosomal spacer region.

Animals↗
PubMed1980

Reinitiation of synthesis of small cytoplasmic RNA species K and L in isolated HeLa cell nuclei in vitro.

Isolated HeLa cell nuclei were used to synthesize low molecular weight RNA species in-vitro. The labelled RNA released from the nuclei during the incubation mainly consists of 5S RNA, pre-tRNA and small cytoplasmic RNA species K and L. All these low molecular weight RNA species are synthesized by RNA polymerase C (or III). The polyanion heparin was applied to study the reinitiation of these RNA molecules in-vitro. A comparison of the kinetics of RNA synthesis in the absence and in the presence of this inhibitor demonstrates a highly efficient in-vitro reinitiation of scRNA species K and L as well as 5S and pre-tRNA by RNA polymerase C. These results indicate a general competence of this enzyme to catalyze the de-novo formation of specific gene products in-vitro.

Cell Nucleus↗
PubMedDate not supplied

A factor discriminating between the wild-type and a mutant polyomavirus enhancer.

Enhancers increase the frequency of transcription initiation from linked promoter elements, most probably as a result of the binding of specific proteins to the enhancer. The polyomavirus early region is expressed in differentiated mouse cells but not in undifferentiated embryonal carcinoma (EC) cells. This host range is a function of the enhancer because polyomavirus mutants selected for growth in EC cells have mutations in the enhancer and the host range is reproduced in transfection assays using the mutant enhancers. To understand the basis for this alteration in enhancer function, we have assayed extracts of EC cells for proteins that can interact with this sequence. We have detected a protein, present in a variety of cells, that can bind to the F441 mutant sequence, but binds only very poorly to the wild-type sequence. We conclude that this sequence alteration has probably generated a binding site for a positive-acting factor that allows the enhancer to function.

Animals↗
PubMedDate not supplied

[The cervix at term--an ultrasonographic study].

Transvaginal sonography with a 5 MHZ probe was used to measure the cervical length, width and the internal os. We examined 37 Primiparae (group 1) and 36 Multiparae (group 2) in the 40th and 41st gestational week vagino-sonographically. All pregnancies were uncomplicated. For comparison between the datas of shortening and thickening of cervix the students t-test showed a significance of p less than 0.05. We registered vagino-sonographically that under painless uterine contractions the cervix shortened with an increase of thickness, while the internal os was constant and opened at least. A reformation of cervix in the relaxation phases was seen.

Adult↗