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Biomedical subjects

G Hansen

Publications and source records attributed to G Hansen.

At least 19 recordsLinked to original sources
PubMed1992

[On ketamine].

Explore the source record for details and available documents.

Humans↗
PubMed1992

A T-DNA transfer stimulator sequence in the vicinity of the right border of pRi8196.

An 8 bp sequence repeated 6 times is present to the right of the mannopine type pRi8196 T-DNA right-border sequence. Experiments were designed to test whether these repeats have a role in T-DNA transfer. Several constructs in which different lengths of pRi8196 right-border region were linked to the cucumopine synthesis gene on an Agrobacterium-Escherichia coli shuttle vector were made. The recombinant plasmids were tested for their efficiency to act as a source of T-DNA in a binary system in which a wild-type Ri plasmid provided virulence and root-inducing functions. The T-DNA transfer efficiency of the constructs was assessed by computing the relative frequency of roots containing cucumopine. Depending on the Ri plasmid used as source of virulence functions, a high level of T-DNA transfer was observed only if 6 (pRi8196) or 5 (pRiA4) repeats were present. These results were confirmed by looking for single-stranded T-DNA molecules (T-strands) in bacteria induced for virulence. The repetition of the 8 bp unit was named 'T-DNA transfer stimulator sequence' (TSS).

Base Sequence↗
PubMed1992

Monoclonal antipeptide antibodies recognize epitopes upon VP4 and VP7 of simian rotavirus SA11 in infected MA104 cells.

To study morphogenetic events of rotavirus SA11-infected MA104 cells with strictly defined reagents we produced monoclonal antibodies against synthetic peptides from both outer capsid proteins VP4 (aa residues 228-241: QNTRNIVPVSIVSR) and VP7 (aa residues 319-326: SAAFYYRV) of simian rotavirus SA11. Two of the selected monoclonal antibodies proved to be reactive with determinants of SA11-infected MA104 rhesus monkey kidney cells, with purified SA11 as well as with the particular peptides used for immunization. The anti-VP4 antibody had a demonstrable neutralizing titer of 200 (50% focus reduction) whereas the anti-VP7 MuMAb revealed no detectable neutralizing activity. In peptide-inhibition experiments, the corresponding peptide inhibited its MuMAb whereas the noncorresponding peptide had no effect on antibody binding to intracellular viral antigen. Localization of VP7 was preceded by VP4 as shown by immunofluorescence microscopy.

Amino Acid Sequence↗
PubMed1992

Intrathecal baclofen. Effects on nocturnal leg muscle spasticity.

Electromyographic activity was recorded from tibialis anterior during nocturnal polysomnography in six patients with severe spasticity of spinal origin. The patients had a baclofen reservoir system implanted subcutaneously into their lumbar subarachnoid space and were studied for two nights in a double-blind, placebo controlled, crossover design. Tibialis anterior electromyographic activity per hour of sleep was reduced on the night of baclofen infusion. In particular, less electromyographic activity occurred after arousal from sleep.

Adult↗
PubMed1991

[Tracheobronchial tumors treated with laser. 7-year experiences at Aker hospital].

The first Nd-YAG laser treatment for endoluminal airway obstruction in Norway was performed at Aker Hospital in November 1983. During the ensuing seven years 68 patients have been treated, involving altogether 172 procedures. During the early years a flexible bronchoscope was used to guide the flexible laser probe, in later years the usual practice has been to use the rigid bronchoscope, 54 patients were treated for malignant tumour, three for semi-malignant and 11 for benign tumour. In general, the best results were achieved with a proximal location of the tumour. Two patients died during the procedure from hypoxia, and one patient died from hemoptysis on the fifth day after operation. Based on retrospective studies of the clinical journal and the results from postmortem examination of 97 consecutive patients who died from pulmonary carcinoma, we anticipated that six of these patients would have benefited from laser treatment on at least one occasion during their disease. In Norway, with an incidence of approximately 400 cases of pulmonary carcinomas each year per million inhabitants, we estimate the need of lung laser procedures to be 25 per million each year.

Adolescent↗
PubMed1991

Agrobacterium rhizogenes pRi8196 T-DNA: mapping and DNA sequence of functions involved in mannopine synthesis and hairy root differentiation.

This paper presents the map and DNA sequence analysis of pRi8196 transferred DNA (T-DNA) genes encoding root-inducing and mannopine synthesis functions. A canonical 24-base-pair border repeat as well as two "pseudoborders" are present at the functional right T-DNA border. To the left of this border are homologs of the mas1' and mas2' genes of TR pRiA4. Next to these are five open reading frames (ORFs) homologous to ORFs 10-14 of TL of pRiA4. ORFs 10-12 (rolA, rolB, and rolC) are less related to their pRiA4 homologs than are the other large ORFs analyzed here. In contrast to T-DNA genes of pRiA4, pRi8196 T-DNA ORFs 11 and 12 (rolB and rolC) are sufficient to induce hairy roots on carrot disks.

Base Sequence↗
PubMed1991

Influence of Na+ and Li+ ions on the kinetics of sodium channel block by tetrodotoxin and saxitoxin.

Voltage clamp experiments were done on single myelinated frog nerve fibres. The rate of block of Na+ channels by tetrodotoxin (TTX) was obtained from changes in peak Na+ current during 1-Hz trains of depolarizing impulses. In hypertonic Na(+)-rich solution (216 mM) the stationary block was reduced compared with Na(+)-poor solutions (54 mM or less; tetramethylammonium ions substituting for Na+). Washout in 216 mM Na+ was faster than in 54 mM Na+. Concentration of Na+ [( Na+]) little affected onset of block. After equilibration in Na(+)-poor TTX solution, a sudden application of Na(+)-rich toxin solution led to a partial relief from block that proceeded faster than the onset in the latter solution. Comparable results were obtained with saxitoxin (STX) and in analogous Li+ solutions. Most of the observed phenomena could be quantitatively fitted by a cyclic model in which cations favour the transition of channels (unblocked and blocked) from a high- to a low-affinity state from which toxin dissociates faster.

Animals↗
PubMed1991

Pathogenesis of infection with a virulent allotropic variant of minute virus of mice and regulation by host genotype.

Neonates of various inbred strains of mice expressed three susceptibility phenotypes in response to infection with the lymphocyte-specific variant of minute virus of mice (MVMi). MVMi caused asymptomatic infections in C57BL/6 (B6) mice, lethal infections with intestinal hemorrhage in DBA/2 mice, and lethal infections with renal papillary hemorrhage in BALB/c, SWR, SJL, CBA, and C3H (H) mice. Sequential virus titration, histology, in situ hybridization with a full-length MVMi genomic probe, and immunohistochemistry for viral capsid antigen were used to compare the pathogenesis of MVMi infection in B6 and H mice. Peak infectious virus titers in heart, lung, liver, spleen, kidney and intestine did not differ between strains but brains of B6 mice, unlike H mice, were refractory to infection. Lesions in H mice consisted of renal papillary infarcts and accelerated involution of hepatic erythropoietic foci. No lesions were seen in B6 mice. In situ hybridization and immunohistochemistry indicated that three cell types were primary targets of MVMi; endothelium, lymphocytes, and hepatic erythropoietic precursors. Renal papillary infarcts in H mice were associated with virus replication in endothelial nuclei of the vasa recta. In contrast to the parity of infectious virus titers between strains, fewer cells in target organs of B6 mice were labeled with the MVMi probe then were labeled in H mice and fewer cells expressed viral capsid antigen. These results indicate (a) that the allotropic variants of minute virus of mice may be useful tools to dissect molecular mechanisms of parvovirus virulence, (b) that the virulence of MVMi for neonatal mice does not reside in its lymphotropism, and (c) that genetic susceptibility to lethal MVMi infection may result from overproduction of noninfectious virus products.

Animals↗
PubMed1991

[A thermostable alpha-amylase from Thermoactinomyces vulgaris: purification and characterization].

Alpha-amylase from Thermoactinomyces vulgaris (strain 94-2A) was purified by cellulose chromatography and gel-chromatography on Sephadex G-75 and subsequently characterised. The enzyme shows a single band in the polyacrylamide gel electrophoresis (PAGE). The isoelectric point was determined to be pH 5.4, and the molecular mass was estimated as 53,000 Dalton by PAGE. The amino acid composition was determined; it shows characteristics of other microbial alpha-amylases. A comparison of the N-terminal sequence with that of other alpha-amylases shows a homology of 66.6% to Taka-amylase. The pH-optimum for the alpha-amylase activity is 4.8 to 6.0 and the temperature optimum 62.5 degrees C. The heat inactivation was investigated under different conditions (temperature, time, Ca2+, EDTA).

Amino Acid Sequence↗
PubMed1989

Cleavage of synthetic peptides by purified poliovirus 3C proteinase.

Synthetic peptides, 14-16 residues in length, were used as substrates for purified recombinant poliovirus proteinase 3C. The sequences of the substrates correspond to the sequences of authentic cleavage sites in the poliovirus polyprotein, all of which contain Gln-Gly at the scissile bond. Specificity of cleavages was demonstrated by analysis of 3C digests of synthetic peptides. Relative rate constants for the cleavages were derived by competition experiments. The rate constants roughly correlated with the estimated half-life of the homologous precursor proteins detected in poliovirus-infected cells. The peptide most resistant to cleavage corresponded to the 3C/3D junction, a site known to be cleaved very slowly by 3C in vivo. Substitution of threonine for alanine in P4 position of this peptide, however, resulted in significant cleavage. This observation supports the hypothesis that the residue in P4 position, in addition to the Gln-Gly in P1 and P1', respectively, contributes to substrate recognition. Ac-Gln-Gly-NH2 was not a substrate for 3C.

3C Viral Proteases↗
PubMed1989

In vitro comparison of velocity profiles and turbulent shear distal to polyurethane trileaflet and pericardial prosthetic valves.

A comparative study of flow dynamics past biomer trileaflet valves and a pericardial bioprosthetic valve under steady and physiological pulsatile flow conditions in vitro is reported in this paper. The velocity profiles and the turbulent shear stresses distal to the valves were measured using laser Doppler anemometry. The authors' results showed that the velocity profiles distal to the trileaflet valves were similar to that measured distal to the pericardial valve. Higher magnitudes of absolute turbulent shear stresses were measured distal to the synthetic valves in comparison to the pericardial valves. However, when the stresses were nondimensionalized with respect to the orifice diameter at the inlet aspect, the stresses were comparable for all of the three valves. With design modifications to increase the orifice diameter at the inlet aspect of the polyurethane valves, the turbulent stresses distal to the valves can be minimized. Such in vitro studies on the flow dynamics past the polyurethane valves can provide information towards design changes to improve the performance characteristics of these valves. Polyurethane valves with flow characteristics comparable to the pericardial valves can be manufactured relatively inexpensively compared to mechanical or tissue valve prosthesis. Hence, the synthetic valves may be a viable alternative for short-term use in total artificial heart devices as a bridge to transplant.

Bioprosthesis↗
PubMed1989

Gastric ulcer is accompanied by a decrease of epidermal growth factor in gastric juice and saliva.

Numerous studies have indicated a role of epidermal growth factor in the maintenance of the gastrointestinal mucosa. In the present study epidermal growth factor concentrations in saliva and gastric juice of patients with gastric or duodenal ulcer or gastritis are compared with those of healthy controls. For this purpose a novel ELISA system has been developed and shown to be sensitive and specific. It is demonstrated that gastric juice and saliva of patients with gastric ulcer contain less epidermal growth factor than the samples of healthy controls (p less than 0.01). Epidermal growth factor concentrations and outputs (product of epidermal growth factor concentration and the volume secreted in 15 min) in the gastric juice of patients with duodenal ulcer do not differ from those of healthy controls.

Duodenal Ulcer↗