Biomedical subjects

I J Sørensen

Publications and source records attributed to I J Sørensen.

11 recordsLinked to original sources

PubMed2000

[Dengue fever].

Dengue virus infections have increased globally. This results in an increased incidence of patients with dengue fever in Denmark. In order to draw attention to this diagnosis among febrile persons returning from a stay in tropical and subtropical areas, we present two cases of dengue virus infection and describe the symptoms and diagnostic possibilities. Dengue Haemorrhagic Fever (DHF) is supposed to occur only in persons who have previously had dengue virus infection and who acquire a second infection with dengue virus.

Adult↗

PubMed2000

Complexes of serum amyloid P component and DNA in serum from healthy individuals and systemic lupus erythematosus patients.

Serum amyloid P component (SAP) binds in vitro to DNA; based on findings in SAP-deficient mice it was proposed that SAP's role is to handle chromatin and DNA, thereby preventing formation of anti-DNA antibodies. For the first time we have shown the presence of Ca2+-dependent SAP-DNA complexes, measured by ELISA, in sera from both healthy volunteers and systemic lupus erythematosus patients (SLE). The concentration of SAP-DNA complexes in SLE sera was significantly lower than in normal sera and particularly low in sera from patients with anti-DNA titers exceeding 50. The complexes were dissociated by the SAP ligand heparin and were not demonstrable in EDTA plasma. Normal sera showed similar capacity to form SAP-DNA complexes with both thymus and Escherichia coli DNA, whereas significantly lower amounts of complexes, in particular with E. coli DNA, were formed in SLE sera. SLE patients with moderate to high anti-DNA titers showed a significant negative correlation between serum SAP's binding of E. coli DNA and the anti-DNA titer.

Antibodies, Antinuclear↗

PubMed1998

Effects of anaesthesia based on high versus low doses of opioids on the cytokine and acute-phase protein responses in patients undergoing cardiac surgery.

BACKGROUND: Cardiac surgery with cardiopulmonary bypass (CPB) evokes a systemic inflammatory response involving the proinflammatory cytokines tumor necrosis factor-alpha (TNFalpha), interleukin (IL)-1, IL-6, IL-8 and anti-inflammatory cytokines such as IL-10. Like IL-10, opioids downregulate the immune responses in vivo and in vitro, including the activity of the cytokine-producing monocytes and granulocytes. The proinflammatory cytokines are potent inducers of the hepatic acute-phase protein synthesis. The aim of the present study was to investigate if choice of anaesthesia, based on high-dose opioids (fentanyl) versus low-dose opioids influenced the release of IL-6, IL-8, and IL-10. Secondly, it was investigated whether serum amyloid P-component (SAP) is an acute-phase protein in man such as C-reactive protein (CRP), with which it is physically and structurally related. METHODS: Sixteen patients submitted to elective coronary artery bypass grafting (CABG) surgery were randomized to either low-dose opioid anaesthesia consisting of thoracic epidural analgesia combined with inhalational anaesthesia (group I) or high-dose fentanyl anaesthesia (group II). From each patient 18 blood samples were taken perioperatively. Cytokine analyses were performed with ELISA, CRP and SAP mere measured with rocket immunoelectrophoresis (RIE). RESULTS: Surgery and CPB elicited a marked, transient and almost simultaneous proinflammatory and anti-inflammatory cytokine response with no differences between the groups. The cytokine levels returned to preoperative levels 1-3 d after operation. Anaesthesia and surgery did not affect SAP plasma levels while patients showed a major increase in CRP concentrations preceding the cytokine responses. CONCLUSION: CABG performed during two different anaesthetic techniques, high-dose fentanyl versus low-dose opioid anaesthesia, elicited a well-defined cytokine response with minor variation in the time course of each cytokine. The cytokine production was not modified by type of anaesthesia. Finally, SAP is not an acute-phase protein in men.

Acute-Phase Proteins↗

PubMed1997

Calcium-dependent and -independent binding of the pentraxin serum amyloid P component to glycosaminoglycans and amyloid proteins: enhanced binding at slightly acid pH.

Serum amyloid P component (SAP), a member of the pentraxin family of proteins, binds calcium-dependently to several ligands including glycosaminoglycans (GAG's). We have investigated the influence of pH on the Ca2(+)-dependent binding of SAP to solid phase GAG's and amyloid fibril proteins (AA and beta2M) by ELISA. An increase in the dose-dependent binding of SAP to heparan sulfate, AA-protein and beta2M was observed as the pH decreased from 8.0 to 5.0. Furthermore, a lower, but significant Ca2(+)-independent binding of SAP to heparan sulfate, dermatan sulfate, AA protein and the amyloid precursor protein beta2M was observed. This binding was also enhanced at slightly acid pH, most pronounced at pH 5.0. The results of this study indicate that SAP can exhibit both Ca2(+)-dependent and -independent binding to ligands involved in amyloid fibril formation and that the binding is enhanced under conditions of slightly lowered pH.

Amyloid↗

PubMed1996

Binding of complement proteins C1q and C4bp to serum amyloid P component (SAP) in solid contra liquid phase.

Serum amyloid P component (SAP), a member of the conserved pentraxin family of plasma proteins, binds calcium dependently to its ligands. The authors investigated SAPs interaction with the complement proteins C4b binding protein (C4bp) and C1q by ELISA, immunoelectrophoresis and electron microscopy. Binding of these proteins to SAP was demonstrated when SAP was immobilized using F(ab')2 anti-SAP, but not when SAP reacted with these proteins in liquid phase; thus the binding to human SAP was markedly phase state dependent. Presaturation of solid phase SAP with heparin, which binds SAP with high affinity, did not interfere with the subsequent binding of C4bp or C1q to SAP. In contrast, collagen I and IV showed partial competition with the binding of C1q to SAP. Using fresh serum, immobilized native SAP bound C4bp whereas binding of C1q/C1 could not be demonstrated. Altogether the results indicate that firm binding of C1q and C4bp to SAP requires that SAP is presented on a solid phase, that C1q and C4bp react with sites distinct from the heparin binding site, and that C1q and collagen I share binding sites on SAP. Immobilized native SAP, aggregated SAP and SAP-heparansulphate complexes induced no detectable complement activation.

Animals↗

PubMed1995

Native human serum amyloid P component is a single pentamer.

Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer) whereas CRP is a single pentameric molecule. We have investigated by gel permeation chromatography the M(r) of SAP in freshly collected human serum and of SAP purified by carbohydrate affinity chromatography and anion exchange chromatography. SAP was monitored by quantitative immunoelectrophoresis and ELISA, and SAP peak fractions were analysed by use of SDS-PAGE, Western blotting, and electron microscopy. The results indicate that native SAP circulates as a single pentamer, a part of which forms complexes with C4b-binding protein. The properties of SAP changed during purification as indicated by rocket immunoelectrophoresis and electron microscopy. Thus, electron micrographs of purified SAP showed a predominance of decamers. However, the decamer form of SAP reversed to single pentamers when purified SAP was incorporated into SAP-depleted serum.

Biopolymers↗

PubMed1995

Multiple isoforms of the human pentraxin serum amyloid P component.

Human serum amyloid P component (SAP) isolated from 20 healthy individuals was analyzed by anion exchange chromatography and isoelectric focusing (IEF) in order to investigate the existence of multiple forms of SAP and interindividual structural differences. Anion exchange chromatography showed one major and several minor subpopulations of SAP. IEF of all SAP isolates showed a previously unreported degree of heterogeneity with six isoelectric forms (pKi range 5.5-6.1) and with minor interindividual differences in respect of isoelectric points. Total enzymatic deglycosylation of SAP reduced the number of bands in IEF to two indicating the existence of two types of polypeptide chains.

Blood Proteins↗

PubMed1994

Calcium-enhanced aggregation of serum amyloid P component and its inhibition by the ligands heparin and heparan sulphate. An electron microscopic and immunoelectrophoretic study.

Serum amyloid P component (SAP) is a pentraxin found in the circulation and in all forms of amyloid deposits. Its physiological and pathophysiological functions are largely unknown. Electron microscopy showed purified human SAP to consist of double pentameric discs compatible with the results of size chromatography. The formation of double pentamers did not require calcium ions. The outer diameter of the discs arranged face-to-face was 11.6 nm and the inner diameter 3.2 nm. The thickness of single and double pentamers was 4.1 and 8.7 nm, respectively. Quadruple pentamers were occasionally seen. The self-aggregation of human SAP molecules was investigated in the presence and absence of calcium ions at different concentrations. In calcium-free solutions few and mostly small SAP aggregates were seen. After addition of calcium at increasing concentration the aggregates grew in size and crystalline-like structures were formed already at 2 mM calcium. At 25 mM calcium, large aggregates with a crystalline array occasionally exhibiting cylinders predominated. Binding of the ligands heparin and heparan sulphate to SAP completely abolished the calcium-enhanced aggregation, but the distribution of the SAP molecules was affected, resulting in strands or groups of adjacent molecules. The electrophoretic mobility of SAP was moreover significantly altered after its calcium-dependent reaction with these ligands. We conclude that purified SAP has a tendency to double pentamer formation and self-aggregation also in the absence of calcium ions. However, aggregation is greatly enhanced even at low concentrations (2 mM) of calcium. SAP's tendency to self-aggregation is abolished after its binding to heparin or heparin sulphate. Furthermore, our TEM studies indicate that purified human SAP freed of its natural ligands has the double pentameric form, whereas the electrophoretic investigations suggest that SAP's interaction with low-molecular-weight natural ligands in serum prevents homodimerization and self-aggregation.

Blotting, Western↗

PubMed1993

[Serum electrolytes and drug therapy of patients admitted to a geriatric department].

The distributions of sodium and potassium in the serum on admission, and the types of medicine used were studied retrospectively in hospitalized geriatric patients (n = 1418). Sodium concentrations below 130 mmol/l were found in 7.4% and potassium concentrations below 3.0 mmol/l in 5.0% of patients. Risk factors for low sodium concentrations were treatment with the combination of thiazide+amiloride, potassium-sparing diuretics, thiazides, emergency hospitalization and low body weight. Risk factors for low potassium concentrations were treatment with the combination of thiazide+amiloride, thiazides and female gender. On an average, patients were given two different drugs from specified groups both on admission and on discharge, but changes in medical treatment were often performed during the hospital stay. Prehospital treatment with thiazide diuretics and the combination of thiazide+amiloride was frequently withdrawn. 38% were given benzodiazepines on discharge. In 40.4% of these, treatment had been started during the hospital stay, most often on account of insomnia.

Aged↗

PubMed1981

Family studies of complement C4 and HLA in man.

At least 12 different C4 gene products with a three band pattern have been identified after electrophoresis of sera pretreated with neuraminidase. Segregation analysis showed at least 12 different C4 haplotypes (or supergenes), of which five represent a single gene product and seven are duplications each composed of an F and an S gene. The data analyzed with respect to linkage showed one recombinant between the C4 and HLAB loci in 154 meioses giving a map distance of C4 HLAB of 0.6 cM. Another recombinant between the C4 and the HLAD loci was found in 101 meioses giving a map distance of C4 HLAD of 1.0 cM. Linkage disequilibrium was found between at least eight C4 haplotypes and certain alleles at the HLAB as well as the HLAD loci. Examinations of 15 families selected through a proband with HLAA 25, HLAB 18 and C2Q0 showed that in almost all cases a slight variant of the C4 supergene F3S2 followed the haplotype HLAA25 HLAB18 C2Q0. No associations were found between the two duplications of C4F3 C4S2 and C4F3 C4S1 and the loci. These findings may indicate that these C4 haplotypes were the original ones preceding the other C4 haplotypes.

Adult↗

PubMed1979

Genetic studies of complement C4 in man.

A C4 variant found in about 5% of the population is described. The fast-moving part of this variant is governed by an allele (Fx) codominant to F. The Fx allele is in very strong linkage disequilibrium with HLA-B17 as the linkage disequilibrium parameter accounted for nearly 100% of the haplotype frequency of B17,Fx. The strong association is also evidenced by the study of 11 families segregating for the Fx allele. There was no instance of recombination between C4 and HLA in 36 informative meioses.

Adult↗