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Biomedical subjects

L Svensson

Publications and source records attributed to L Svensson.

At least 19 recordsLinked to original sources
PubMed1992

Rapid changes in ascorbate and dopamine release in rat nucleus accumbens after intracerebroventricular administration of NMDA.

In vivo voltammetry at electrochemically pretreated carbon fibre electrodes was used to investigate the effect of intracerebroventricular (i.c.v.) administration of N-methyl-D-aspartic acid (NMDA) on neuronal activity in rat nucleus accumbens. Infusion of a low dose of NMDA (1 nmol) was followed a few minutes later by rapid changes in both Peak 1 and Peak 2 heights indicating large but short-lived increases in the extracellular concentrations of ascorbate and catecholamines, respectively. These responses did not seem to be dependent on the dose infused since infusion of NMDA for a longer time period neither changed the amplitude nor the time-course of these effects. The increase in Peak 2 height was resistant to pargyline pretreatment indicating that this response mainly reflected the release of dopamine. The administration of NMDA was followed by behavioural activation in the animals but not convulsions. Co-administration of the competitive NMDA receptor antagonist, CPP (1 nmol), completely blocked these effects while the acetylcholine receptor antagonist, atropine (1.5 nmol), and the GABA receptor antagonist, picrotoxin (1 nmol), failed in this respect. The phenomenon spreading depression is discussed as a possible explanation of these results.

Animals↗
PubMed1992

99mTechnetium-dimercaptosuccinic acid scan in the diagnosis of acute pyelonephritis in children: relation to clinical and radiological findings.

Seventy-two children, 59 girls and 13 boys, 0.1-15.9 (median 1.1) years of age, with acute pyelonephritis (APN) were investigated with the aid of a dimercaptosuccinic acid (DMSA) scan, renal ultrasonography (US) and a desmopressin test within 5 days of admission. Sixty-two children were reinvestigated approximately 2 months later when intravenous urography (IVU) and micturition cysto-urethrography were also performed. During infection, 92% of the children showed changes in the DMSA scan with 69% by US, and the two investigations agreed in 58% of the kidneys. At follow-up, 68% showed changes in the DMSA scan, 47% by US and 48% by IVU. The DMSA scan and IVU agreed in 60% of the kidneys. Twenty-nine percent of the children had vesico-ureteric reflux (VUR). The presence of grade greater than or equal to 3 VUR was associated with greater defects on the DMSA scan during infection, and at follow-up with a higher frequency of persistent changes compared with no VUR (P less than 0.02 and 0.01, respectively). During infection the size of the defect on the DMSA scan correlated with renal volume and C-reactive protein and inversely with the glomerular filtration rate, and at follow-up it correlated inversely with the renal concentration capacity. The DMSA scan is a sensitive method for diagnosing and localizing APN in children, and findings on DMSA scan show a weak but significant correlation with routine clinical and radiological parameters. It is suggested that persistent renal damage after APN in children without VUR may be more common than previously assumed.

Acute Disease↗
PubMed1992

A family outbreak of gastroenteritis caused by group C rotavirus.

A family outbreak of gastroenteritis caused by group C rotavirus is described. All five members of the family, with children between 8 and 15 years of age, fell ill with diarrhea. The diagnosis was initially based on the detection of rotavirus RNA showing a typical group C profile in gel electrophoresis in stool samples, and it was serologically verified from patient sera using a cell culture adapted porcine group C rotavirus as a source of standard antigen. All collected serum samples from the family contained IgM and/or IgG class antibodies to group C rotavirus measurable by immunofluorescence antibody test (IFAT). Group C rotavirus specific IgM class antibodies were present in the early serum samples in 3/4 patients. A roller tube neutralization test (NT) was established to demonstrate neutralizing antibodies to porcine group C rotavirus in human sera. These methods can be used to detect serologically group C rotavirus infections.

Adolescent↗
PubMed1992

Characterisation of the anti-A antibody response following an ABO incompatible (A2 to O) kidney transplantation.

Anti-A,B antibodies produced in a blood group OLe(a-b-) recipient receiving a kidney graft from a blood group A2Le(a-b+) donor have been analysed for their ability to bind to different glycosphingolipid antigens. Solid-phase RIA using pure glycosphingolipid antigens and a chromatogram binding assay using total nonacid glycosphingolipid fractions from erythrocytes of different human blood group phenotypes together with pure glycolipid antigens were used as assay systems. Serum antibodies were shown to bind equally well to A (types 1, 2, 3 and 4) and B (types 1 and 2) antigenic structures but no binding to H antigens (types 1, 2 and 4) was detected. After adsorption of serum antibodies on A1 Le(a-b+) erythrocytes there was a residual anti-A antibody activity which could not be adsorbed by synthetic A-trisaccharides coupled to crystalline silica (Synsorb-A). These residual antibodies, which are not present in a pretransplant serum sample, had a specificity for the A antigen with type 1 core saccharide chain and the binding epitope obviously included both the N-acetylgalactosamine and the N-acetylglucosamine. The fucose residue was apparently not obligate for binding. The conformation of the sugar units involved in the binding epitope was determined.

ABO Blood-Group System↗
PubMed1992

Group C rotavirus requires sialic acid for erythrocyte and cell receptor binding.

Current immunological and biochemical information regarding the hemagglutinin and virus-cell interactions of rotavirus is obtained exclusively from studies with group A rotaviruses. In this study, I report that the immunologically and genetically distinct group C rotavirus also possesses a hemagglutinin. The viral hemagglutinin was identified on a cultivable porcine group C rotavirus strain (strain AmC-1) by using agglutinated human and guinea pig erythrocytes. Neuraminidase treatment of fresh human erythrocytes or blocking with glycophorin A or fetuin prevented hemagglutination. Infection of swine testicular cells with group C AmC-1 virus was also prevented by glycophorin A, fetuin, and neuraminidase treatment, suggesting that sialic acid constitutes an essential part of the cell receptor.

Animals↗
PubMed1992

Raised plasma concentrations of endothelin-1 and -3 in marmosets with acute aortic stenosis: no relation to the renin-angiotensin system.

Plasma levels of endothelin (ET), plasma renin activity (PRA) and angiotensin II (Ang II) were measured in anaesthetized marmosets exposed to acute aortic stenosis proximal to the renal arteries. In vehicle experiments, ET rose from 5 +/- 2 to 38 +/- 4 pg ml-1, PRA from 5 +/- 2 to 99 +/- 21 ng ml-1 h-1 and Ang II from 21 +/- 4 to 213 +/- 76 pg ml-1. Administration of renin inhibitor and angiotensin converting enzyme inhibitor reduced PRA and Ang II to control levels, while the plasma levels of ET increased further (51 +/- 10 and 71 +/- 16 pg ml-1, respectively). During aortic stenosis the two isoforms ET-1 and ET-3 appeared in the circulation, while in conscious control animals only ET-1 was found. It is concluded that the increased plasma levels of ET in our primate model could not be ascribed to the increased circulating levels of PRA and Ang II.

Acute Disease↗
PubMed1991

Phosphorylated Mr 32,000 dopamine- and cAMP-regulated phosphoprotein inhibits Na+,K(+)-ATPase activity in renal tubule cells.

Dopamine inhibits Na+,K(+)-ATPase activity in several renal tubule segments and thereby regulates urinary Na+ excretion. We now show that a phosphopeptide of 31 amino acids, corresponding to residues 8-38 of the protein phosphatase inhibitor DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of Mr 32,000), mimics the inhibitory action of dopamine on Na+,K(+)-ATPase activity in renal tubule cells from the ascending limb of the loop of Henle. The dephosphorylated form of the peptide is ineffective. The results indicate that dopamine acts through a protein phosphorylation pathway to regulate the activity of an ion pump. In addition, the data suggest that inhibition of protein phosphatase 1 by phophorylated DARPP-32 is a component of the mechanism by which dopamine regulates urinary Na+ excretion.

Amino Acid Sequence↗
PubMed1991

A pharmacokinetic study of prednimustine as compared with prednisolone plus chlorambucil in cancer patients.

The pharmacokinetic characteristics of prednisolone and of chlorambucil and its beta-oxidized metabolite, phenylacetic mustard (PAM) were studied in plasma after the oral administration of 200 mg prednimustine (Sterecyt) and a regimen consisting of 20 mg prednisolone plus 20 mg chlorambucil, respectively. A total of 12 cancer patients completed this trial. The drugs were given in a cross-over study as single doses, and serial plasma samples were collected for 32 h. Chlorambucil and PAM were assayed by a gas chromatographic/mass spectrometry method and prednisolone, by radioimmunoassay. The median relative availability of the prednisolone and chlorambucil moiety in prednimustine was 19% and 16%, respectively. Prednisolone, as well as chlorambucil and PAM, appeared later and at a significantly lower concentration in plasma after treatment with prednimustine as compared with the mixture of chlorambucil and prednisolone. We also found that the elimination phase of chlorambucil and PAM in plasma is prolonged after the administration of prednimustine as compared with chlorambucil per se. In contrast, the elimination of the prednisolone moiety of prednimustine and that following the administration of a plain prednisolone tablet did not seem to differ. The modified plasma profile of the alkylating components following prednimustine administration may be important for the clinical efficacy of prednimustine.

Adult↗
PubMed1991

Adaptation and serial passage of porcine group C rotavirus in ST-cells, an established diploid swine testicular cell line.

A porcine group C rotavirus (strain Cowden-AmC-1) was adapted and serially passaged in an established diploid swine testicular cell line (ST cells). Growth of group C rotavirus in ST cells, which in maintenance medium required trypsin, but not pancreatin resulted in cytopathic effect characterized by cellular stranding and subsequent cell lysis. Active replication and assembly were confirmed by RNA profile analysis, immune electron microscopy and immunofluorescence. Adaptation of non-group A rotavirus to a continuous cell line has not previously been reported and should facilitate progress in diagnostic procedures and vaccine development.

Adaptation, Physiological↗
PubMed1991

Evidence for a role for dopamine in the diazepam locomotor stimulating effect.

It is well known that benzodiazepines produce dependence in humans and locomotor stimulation in experimental animals. In this study the possible involvement of catecholamines in the diazepam-induced locomotor stimulation in mice were investigated. Diazepam was found to have a biphasic effect; increasing locomotor activity at a low dose (0.25 mg/kg), while decreasing it at higher doses (greater than 0.5 mg/kg). The locomotor stimulating effect of diazepam was effectively blocked by pretreatment with the benzodiazepine receptor antagonist flumazenil, as well as with the catecholamine synthesis inhibitor alpha-methyltryrosine and the dopamine receptor antagonists haloperidol, spiperone and SCH 23390. Taken together, these data indicate that the locomotor stimulating effect observed after low doses of diazepam is due to activation of brain dopaminergic systems involved in locomotor activity. The observations are discussed in relation to the hypothesis that dependence-producing drugs activate specific brain reward systems.

Animals↗
PubMed1991

Evidence for a dissociation between cardiovascular and behavioral reactivity in the spontaneously hypertensive rat.

Spontaneously hypertensive rats of the Okamoto strain (SHR) were compared with normotensive rats of the Wistar-Kyoto strain (WKY) on the acoustic startle response in rats prepared for simultaneous blood pressure recordings. Blood pressure was continuously recorded by means of an indwelling cannula in the caudal tail artery. The presentation of the startle stimulus caused a blood pressure response in both strains consisting of an initial increase in blood pressure followed by a decrease and after that a longer lasting, but less pronounced second increase in pressure. The startle-elicited increase in blood pressure was significantly elevated in SHRs and at the same time the acoustic startle response was depressed as compared to WKY rats. These data indicate a dissociation between cardiovascular and behavioral reactivity in the SHR.

Acoustic Stimulation↗
PubMed1991

Symmetric infection of rotavirus on polarized human intestinal epithelial (Caco-2) cells.

When rotavirus infects the mature villus tip cells of the small intestine, it encounters a highly polarized epithelium. In order to understand this virus-cell interaction more completely, we utilized a cell culture-adapted rhesus rotavirus (RRV) to infect human intestinal (Caco-2) and Madin-Darby canine kidney (MDCK-1) polarized epithelial cells grown on a permeable support. Filter-grown Caco-2 cells and MDCK-1 cells, producing a transepithelial resistance of 300 to 500 and greater than 1,000 omega . cm2, respectively, were infected from either the apical or basolateral domain with RRV or Semliki Forest virus. Whereas Semliki Forest virus infection only occurred when input virions had access to the basolateral domain of MDCK-1 or Caco-2 cells, RRV infected MDCK-1 and Caco-2 monolayers in a symmetric manner. The effect of rotavirus infection on monolayer permeability was analyzed by measuring the transepithelial electrical resistance. Rotavirus infection on filter-grown Caco-2 cells caused a transmembrane leak at 18 h postinfection, before the development of the cytopathic effect (CPE) and extensive virus release. Electrical resistance was completely abolished between 24 and 36 h postinfection. Although no CPE could be detected on RRV-infected MDCK cells, the infection caused a transmembrane leak that totally abolished the electrical resistance at 18 to 24 h postinfection. Cell viability and the CPE analysis together with immunohistochemistry and immunofluorescence data indicated that the abolishment of resistance across the monolayer was due not to an effect on the plasma membrane of the cells but to an effect on the paracellular pathway limited by tight junctions. Attachment and penetration of rotavirus onto Caco-2 cells caused no measurable transmembrane leak during the first hour of infection.

Animals↗
PubMed1990

The role of the dopaminergic system in the modulation of the acoustic startle response in the rat.

The (+) and (-) isomers of 3-(3-hydroxyphenyl)-N-propylpiperidine (3-PPP) (2-32 mg/kg) were tested for their effects on the acoustic startle response in the rat and these effects were compared with those of apomorphine and haloperidol. Both startle amplitude and startle latency were recorded. (+)-3-PPP produced a dose-dependent prolongation of startle latency. No other significant effects of the 3-PPP isomers were observed. Apomorphine (0.75-3 mg/kg) produced a dose-dependent increase in startle amplitude concurrent with a dose-dependent prolongation of startle latency. Both these effects were blocked by haloperidol. Haloperidol by itself produced a significant decrease in startle amplitude at the highest dose used (1.6 mg/kg). These and other data suggest that activation of both dopamine D-1 and dopamine D-2 receptors is essential for the stimulatory effects of dopamine receptor agonists on the acoustic startle response in the rat.

Animals↗
PubMed1990

Enteric adenoviruses.

Human adenoviruses are classified into 47 serotypes and six subgenera (A-F) with different tropisms. In recent years adenovirus type 40 (Ad40) and 41 (Ad41) of subgenus F have been shown to be causative agents in enteric infections, which is second in importance only to rotaviruses as a cause of infantile gastroenteritis. Infection with EAds occurs worldwide and has been associated with 4-17% of cases of diarrhoea in children. AD40 and Ad41 primarily affect young children less than 2 years of age and occur throughout the year. The clinical characteristics include watery diarrhoea accompanied by vomiting, low grade fever and mild dehydration. A distinct feature of EAds infection is the protracted diarrhoea (mean 8.6 and 12.2 days for Ad40 and Ad41, respectively). Respiratory symptoms are infrequent. Serotypes Ad40 and Ad41 differ from all other (established) adenoviruses by being unable to replicate in conventional cell cultures. These fastidious viruses only grow in selected cell lines, 293 cells being the most commonly used. In spite of the difficulty of isolating Ad40 and Ad41, they can be directly identified and typed by ELISA and solid-phase immune electron microscopy. The amount of viral DNA in stool specimens is sufficient for identification by DNA restriction and dot-blot assays. The recent development of highly sensitive and specific monoclonal antibody-based ELISAs enable accurate diagnosis of adenovirus gastroenteritis in routine work and make possible the evaluation of the role of the enteric adenoviruses in diarrhoeal disease in the developing countries.

Adenoviridae↗
PubMed1990

Lack of cosegregation of the subgroup II antigens on genes 2 and 6 in porcine rotaviruses.

The rotavirus subgroup I and II specificities associated with gene 2 and 6 products (vp2 and vp6, respectively) were shown not to cosegregate in a number of porcine rotavirus strains. The porcine OSU rotavirus strain and OSU-vp7-like strains were all found to possess a subgroup II-specific region on vp2 and a subgroup I-specific region on vp6. Of interest is the observation that the subgroup II-specific epitope on vp2 appears to be present only in human and porcine rotavirus strains, suggesting a possible human-pig ancestral lineage for gene 2.

Animals↗