Search PubMed⌕ Search

Biomedical subjects

U Hansen

Publications and source records attributed to U Hansen.

80 records · Page 5Linked to original sources
PubMed1983

Sequences controlling in vitro transcription of SV40 promoters.

A series of deletion mutants of SV40 were tested for early and late promoter activity in vitro in a transcription extract prepared from HeLa cells. These mutants had previously been characterized for expression in vivo. Transcription in vitro from both the SV40 early and late promoters was strongly dependent on an upstream region of DNA that contains six direct GC repeats. Sequences spanning two or more of these repeats stimulated transcription in a bidirectional fashion, at distances of 50-200 bp. These sequences may function by mediating the activity of a specific transcriptional factor. Little effect on transcription in vitro was observed upon deletion of the 72-bp enhancer elements. With this exception, the sequence dependence of early and late transcription in vitro was similar to that observed previously in vivo, both of the region including the GC repeats and of the early TATA sequence.

Base Sequence↗
PubMed1983

Necrotizing vasculitis in athymic rats with infarct kidney hypertension.

Infarct kidney hypertension was induced in congenital athymic nude rats and in their haired normal littermates. In both groups a significant and similar elevation of blood pressure was observed. The mesenteric vessels were studied histologically five, 12 and 20 days after operation. Necrotizing vasculitis with and without perivascular inflammatory reactions was found in mesenteric arteries and arterioles in six out of six athymic and in six out of 11 control rats. In sham operated athymic rats and in haired littermates neither hypertension nor vasculitis was observed. These observations indicate that the thymus play no role in the pathogenesis of acute hypertensive vascular disease.

Animals↗
PubMed1983

The pharmacokinetics of frusemide are influenced by age.

After a 24 h control period 80 mg frusemide was given intravenously over 2 min to a group of young and a group of elderly healthy male volunteers. The serum concentration of frusemide and the excretion in urine of the drug and a glucuronidated metabolite were followed for 24 h. The elimination of the drug from serum was described by an open two compartment model. The serum clearance (CLs) was 170 +/- 19 ml min-1 in the young and 129 +/- 11 ml min-1 in the elderly (P less than 0.01) and the average renal clearance (CLr) was 67% of CLs in the young and 58% of CLs in the elderly (NS). The average amount of unchanged frusemide in the urine during the first 30 min was 30 +/- 6 mg in the young but only 20 +/- 4 mg in the elderly (P less than 0.01). The albumin concentration in serum was 15% lower in the elderly but on the average the protein bound fraction of frusemide was 98.6% in both groups. The Vd ss did not differ between the two age groups (0.130 1 kg-1) but the elimination half-life was 70 +/- 20 min in the young and 102 +/- 33 min in the elderly (P less than 0.05). In the young 11.4 +/- 5.0 mg frusemide was excreted as a glucuronidated compound whereas this figure was only 5.4 +/- 2.9 mg in the elderly (P less than 0.01). It is concluded that the age-related changes in the fate of unchanged frusemide in the organism mainly can be explained by a reduction in the tubular secretion of the drug which in turn may be caused by a reduction in renal plasma flow.

Adult↗
PubMed1981

T antigen repression of SV40 early transcription from two promoters.

The SV40 early mRNAs encode large (T) and small (t) tumor antigens. During the lytic cycle, the 5' termini of the early mRNAs undergo a shift: shortly after infection only an initiation site downstream from the TATA box is utilized; later an upstream initiation site becomes prominent. Both initiation sites are utilized in an in vitro transcription extract. D2T, a T antigen analog, specifically represses transcription in vitro from both initiation sites, but at different concentrations. Binding of D2T to site I suppresses initiation from the site downstream of the TATA box; binding to sites II and I suppresses initiation from the upstream site. The role of T antigen binding in repression of transcription and in the shift of initiation sites on the early strand is discussed.

Antigens, Polyomavirus Transforming↗
PubMed1981

Sequential transcription-translation of simian virus 40 by using mammalian cell extracts.

Ribonucleic acids (RNAs) transcribed in vitro by using the whole-cell extract system of Manley et al. (Proc. Natl. Acad. Sci. U.S.A. 77:3855-3859, 1980) were tested for their efficiency and fidelity in directing protein synthesis in reticulocyte lysates. Simian virus 40 deoxyribonucleic acid (DNA), cleaved by various restriction endonucleases, was used as the template. Successful translation of the small tumor antigen t, as well as the capsid proteins VP1, VP2, and VP3, was detected by immunoprecipitation analysis. Although no synthesis of large T antigen was detected, use of this technology allows detection of large T synthesis resulting from the correct splicing of as little as 0.2% of the in vitro RNA transcripts, making it ideal for use as an in vitro splicing assay. Transcripts synthesized in vitro were used as messages at least as efficiently as were viral messenger RNA's (mRNA's) synthesized in vivo; and in the case of small t, there was more efficient translation of small t mRNA synthesized in vitro than of small t mRNA synthesized in vivo. The transcripts that served as mRNA's for the various polypeptides were identified by using the following two criteria. (i) The sensitivity of synthesis of a given protein to digestion of the template DNA with restriction enzymes allowed the localization of the promoter and coding regions. (ii) Translation of size-fractionated RNA allowed confirmation of the transcript-mRNA assignments. With these techniques we found that VP2, VP3 and, in some cases, VP1 synthesis resulted from the initiation of translation at internal AUG codons. In fact, families of polypeptides were produced by initiation of translation at AUG codons within sequences coding for VP1 and T, presumably as a result of transcription initiation events that generated 5' ends immediately upstream from these AUGs. Application of this technology for the identification of coding regions within cloned DNA fragments is discussed.

Animals↗
PubMed1980

Diagnosis of pre- and postnatal rubella by demonstration of specific IgM-class antibodies by a microplate immunofluorescence test.

An indirect immunofluorescence technique employing rubella virus infected SIRC-cells grown in flat-bottomed plastic plates is described for the detection of specific IgM-class rubella antibodies in serum fractions obtained by sucrose density ultracentrifugation. The results were read by means of a fluorescence microscope with an incident light illuminator. A total of 176 serum specimens from five groups of patients were used for determination of the specificity and sensitivity of the test. The technique proved to be less time consuming and in addition to be more sensitive than the hemagglutination-inhibition method for the detection of rubella IgM-class antibodies.

Antibodies, Viral↗
PubMed1976

Formation of lipid-linked sugar compounds in Halobacterium salinarium. Presumed intermediates in glycoprotein synthesis.

The ability of bacitracin to inhibit the growth of Halobacterium salinarium suggested that glycosylation of the major envelope component, a high molecular weight glycoprotein, might occur via a pathway involving lipid intermediates. This report demonstrates that the cells have enzymatic activities for formation of lipid-linked sugar compounds having the expected properties of such intermediates. Whole cell homogenate catalyzed the transfer of sugar from UDP-glucose, GDP-mannose, and UDP-N-acetyglucosamine to endogenous lipid acceptors. Two lipid products were formed from UDP-glucose, two from GDP-mannose, and one from UDP-N-acetylglucosamine. Characterization of the partially purified lipids by ion exchange chromatography, thin layer chromatography, and mild acid and base hydrolysis showed the major product in each case to have the properties expected for polyisoprenyl phosphoglucose, polyisoprenyl phosphomannose, and polyisoprenyl pyrophospho-N-acetylglucosamine. Estimates of chain length by thin layer chromatography indicate that the lipid has 11 to 12 isoprene identity as a C55-60-polyisoprenyl pyrophospho-N-acetylglucosamine. The N-acetylglucosamine transferase, present in cell envelope preparations, was partially characterized. The enzyme was found to be extremely halophilic, specifically requiring a high concentration of KCl. Optimum activity was obtained at 4 m KCl and partial substitution of K+ by Na+ resulted in a decrease in activity.

Cell Membrane↗