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Biomedical subjects

T Krusius

Publications and source records attributed to T Krusius.

At least 55 records · Page 3Linked to original sources
PubMed1992

Risk factors for hepatitis C virus antibody positivity in blood donors in a low-risk country.

Demographic variables, sexual risk behavior and prevalence of parenteral risk factors were studied in 305 randomly selected donors seronegative for hepatitis C virus, in 170 randomly selected donors reactive on solely enzyme-linked immunosorbent assay (ELISA C-100), in 71 consecutive donors reacting indeterminately according to the second-generation recombinant immunoblot assay (RIBA II) and in 46 consecutive donors found to be positive using the RIBA II. Donors who were positive by RIBA II had significantly more often a risk factor, for example use of intravenous drugs or previous blood transfusion, than donors reacting indeterminately (34 out of 46) (73.9%) versus 14 out of 71 (19.7%, p = 0.0000). Donors reacting indeterminately by RIBA II had one of those risk factors significantly more often than seronegative donors (14 out of 71) (19.7%) versus 23 out of 280 (7.8%, p < 0.005). When donors either positive or indeterminate by RIBA II were compared with donors negative for hepatitis C antibodies, the odds ratio for a possible parenteral source of infection was 7.6 (p = 0.0000). Subjects who had received a poor education (odds ratio 0.3, p < 0.001) or who lived in southern Finland (odds ratio 2.3, p < 0.05) were also at higher risk for being positive or indeterminate in RIBA II. First-time donors were also prone to having antibodies according to RIBA II (odds ratio 2.2, p = 0.1), whereas sexual risk behavior, gender, age, occupational class and type of residential area were not risk factors for hepatitis C antibodies in RIBA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Expression of decorin in human tissues and cell lines and defined chromosomal assignment of the gene locus (DCN).

Earlier studies had shown that the expression of the gene coding for one eminent connective tissue proteoglycan, decorin (DCN), is deficient in the fibroblasts of 3 out of 15 Marfan patients (Pulkkinen et al., 1990). To obtain more information on the expression of this gene, various human tissues and cell lines were studied. High mRNA levels of decorin were detected in aorta, lung, skin, kidney, smooth muscle, and placenta, whereas significantly lower mRNA levels were found in the rest of the tissues analyzed. Two sizes of transcripts were observed in all tissues. The two transcripts of decorin most probably do not represent two different genes, since in situ hybridization gave only one strong signal, placing the gene in 12q21----q22. No tissue-specific differences in the two mRNA species of decorin were detected. This is in contrast to the gene of versican, another connective tissue proteoglycan gene, that was analyzed as a control; high expression of a longer transcript of the versican gene was found in brain and smooth muscle, whereas the shorter transcript was predominant in all other tissues studied. DCN was actively transcribed in cultured mesenchymal cells, whereas in cells of endothelial or epithelial origin, the transcription level was undetectable. These tissue- and cell type-specific variations in the expression of DCN may help to explain the complex phenotypic variation typical of individuals with Marfan syndrome.

Adult↗
PubMed1991

Determination of anti-IgA antibodies with a flow cytometer-based microbead immunoassay (MIA).

A flow cytometer-based microbead immunoassay (MIA) was employed to detect anti-IgA antibodies in patients with IgA deficiency. 3 microns latex particles were coated with purified IgA and serum anti-IgA antibodies of the IgG class were detected with FITC-conjugated anti-human IgG. Antibodies against three different IgA preparations were tested from 22 patients samples as well as 20 controls and compared with a conventional enzyme-linked immunosorbent assay (ELISA) and a passive hemagglutination assay (HA). There was a very close correlation between the results obtained with the MIA and the ELISA assay and between MIA and the HA. Because of the low intra-assay variation and good linearity of the assay, the analysis of one single serum dilution was sufficient to determine the anti-IgA level of a patient and no titration series was required. We conclude that MIA is a satisfactory alternative method for routine anti-IgA antibody determinations. For laboratories already equipped with a flow cytometer the assay is cost effective.

Agammaglobulinemia↗
PubMed1991

Transmission of hepatitis C virus to sexual partners of seropositive patients with bleeding disorders: a rare event.

Sexual transmission of hepatitis C virus (HCV) was studied in 30 partners to anti-HCV positive multitransfused patients with a bleeding disorder. Anti-HCV ELISA C-100 was used as a screening test. Positive results were confirmed with the first generation RIBA test. Indeterminate samples were tested also with the second generation RIBA to verify the positivity. The time of sexual exposure added up was at least 95 years. 29 partners were anti-HCV seronegative. Only 1 partner was anti-HCV indeterminate. Thus sexual transmission of HCV was a rare event.

Adult↗
PubMed1991

Multidrug resistance.

Resistance of malignant cells to cytotoxic agents is often a limiting factor to successful chemotherapy. The classical multidrug resistance is characterised by overexpression of a membrane protein, P-glycoprotein, which acts like a drug extruding pump reducing accumulation of cytotoxic agents inside malignant cells, thereby preventing their function. Resistance is expressed simultaneously towards several structurally unrelated drugs. P-glycoprotein is also expressed in many normal human tissues, e.g., in the gastrointestinal tract, and this may be the reason for intrinsic resistance observed clinically in cancers derived from certain tissues. More often multidrug resistance is acquired during chemotherapy. The physiological function of P-glycoprotein is still unknown but it may have a role in cellular detoxification and secreting mechanisms. Interest in the phenomenon of multidrug resistance centres on the correlation of P-glycoprotein expression to clinical drug resistance. Another goal is to find mechanisms by which the function of P-glycoprotein as a multidrug transporter is prevented and drug resistance reversed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Deficient expression of the gene coding for decorin in a lethal form of Marfan syndrome.

The markedly decreased level of the messenger RNA of decorin, an abundant dermatan/chondroitin sulfate proteoglycan was found in the skin fibroblast culture of a lethally sick Marfan infant. Also, the amount of decorin polypeptide in the culture medium of the fibroblasts of this infant was markedly decreased. When the effect of interleukin-1 beta on the transcription of decorin was tested in these fibroblasts, the response was deficient as compared to control fibroblasts whereas transcription of type I and III collagen genes and versican was stimulated normally. The decreased decorin mRNA level, unresponsive to interleukin-1 beta in this lethally sick Marfan patient, stresses the significance of this proteoglycan in the formation of normal connective tissue. Furthermore, the low expression of this gene could be responsible for the connective tissue findings in this patient, representing a rare type of Marfan syndrome. The identical finding in three other, unrelated Marfan individuals suggests a more general significance of deficient decorin expression in this disease.

Blotting, Western↗
PubMed1989

Characterization of one phenotype of human periodontal granulation-tissue fibroblasts.

Human granulation-tissue fibroblasts were cultured from oral chronic inflammatory lesions and compared with fibroblasts of healthy gingival connective tissue with respect to cell-surface sialoglycoproteins, and the synthesis of extracellular matrix components. Granulation-tissue fibroblasts exhibited a slower growth rate and larger size than their controls. Their cell-surface sialoglycoproteins resembled those of the control cells, except that the relative amount of glycoproteins in the 140-kd region was lower. The ratio of mRNAs for pro alpha l (I) and pro alpha l (III) collagen chains was decreased in granulation-tissue fibroblasts, although electrophoretic fractionation of the proteins did not reveal consistent differences in type I/type III collagen ratio. Granulation-tissue fibroblasts secreted into the culture medium a dermatan sulfate proteoglycan with a lower molecular weight. After digestion with chondroitinase ABC, the molecular weight of the core protein appeared to be identical with that of the control fibroblasts, suggesting a difference in the glycosylation of the core protein. These results support the theory that granulation-tissue fibroblasts represent a distinct phenotype of fibroblastic cells.

Adolescent↗
PubMed1988

The small dermatan sulphate proteoglycans synthesized by fibroblasts derived from skin, synovium and gingiva show tissue-related heterogeneity.

Dermatan sulphate proteoglycans (DSPGs) synthesized in the presence of 35SO4 were characterized in culture media of fibroblast lines obtained from skin, synovium, and gingiva. The molecular mass of DSPG varied from 95-130 kDa as estimated by SDS/polyacrylamide-gel electrophoresis. Gingival fibroblasts constantly produced larger DSPGs than skin fibroblasts. This was due to the larger dermatan sulphate (DS) chains, which also showed tissue-related heterogeneity in the distribution of 4- and 6-sulphated disaccharide units. The N-glycosylated cores (44 and 47 kDa) obtained following chondroitinase ABC treatment were of identical size in all tissues. The cores from the different tissues were also of the same size (38 kDa) when addition of the N-linked oligosaccharides was inhibited by tunicamycin or when they were removed by N-glycanase treatment. No evidence for low-molecular-mass sulphated oligosaccharides was found. All tissues contained two mRNA species (1.6 and 1.9 kb) for the DSPG core protein. These data suggest that the pattern of transferase activities involved in the construction of DS chains differs from one tissue to another. This variation may modulate the functions of DSPG in the extracellular matrix.

Blotting, Northern↗
PubMed1988

Human recombinant interleukin-1 regulates cellular mRNA levels of dermatan sulphate proteoglycan core protein.

Human skin fibroblasts were exposed to various concentrations (from 0.01 to 5.0 units/ml) of human recombinant interleukin-1 alpha and interleukin-1 beta (IL-1 alpha and IL-1 beta). Both IL-1 alpha and IL-1 beta were found to increase dermatan-sulphate-proteoglycan (DSPG) core-protein mRNA levels. Maximal increase (3.0-fold) was seen at 48 h after addition of 1 unit of IL-1 beta/ml. In spite of the elevated DSPG-core-protein mRNA only a slight increase (from 10 to 18%) could be seen in the production of DSPG to cell-culture medium. No changes in the molecular mass of DSPG could be detected.

Aggrecans↗
PubMed1987

A fibroblast chondroitin sulfate proteoglycan core protein contains lectin-like and growth factor-like sequences.

We have isolated cDNA clones that code for a proteoglycan-related polypeptide with unique properties. A lambda gt11 expression library made from human fibroblast mRNA was screened with an antiserum made against a proteoglycan fraction from human fetal membranes. One group of positive clones revealed an open reading frame coding for 685 amino acids from the COOH terminus of a polypeptide. This amino acid sequence contains a domain that is strongly homologous with the COOH-terminal core protein domain of the large aggregating cartilage proteoglycan. This domain also contains sequences that are homologous with vertebrate lectins that bind terminal galactosyl, N-acetyl-glucosaminyl or mannosyl residues. On the NH2-terminal side of the lectin-like domain the cDNA-derived amino acid sequence contains two epidermal growth factor-related segments. The cDNA clones were shown to belong to a chondroitin sulfate proteoglycan by using antisera made against two peptides predicted from the cDNA sequence. These antisera were reactive with a proteoglycan fraction from fibroblasts after chondroitinase treatment of the fraction but not after treatment with heparinase or no treatment. Among the several polypeptides reactive with the anti-peptide antibodies the largest one, corresponding to a molecular weight of about 400,000, is likely to be the intact core protein, whereas the smaller polypeptides may be processing products or products of artifactual proteolysis. These results show that the amino acid sequence belongs to a proteoglycan core protein, and the sequence, therefore, provides a molecular definition to this proteoglycan. The lectin-related and growth factor-like sequences in the core protein of this proteoglycan suggest that it may play a role in intercellular signaling.

Aggrecans↗
PubMed1987

Structural studies on sialylated and sulphated O-glycosidic mannose-linked oligosaccharides in the chondroitin sulphate proteoglycan of brain.

We have previously described the structures of neutral and sialylated O-glycosidic mannose-linked tetrasaccharides and keratan sulphate polysaccharide chains in the chondroitin sulphate proteoglycan of brain. The present paper provides information on a series of related sialylated and/or sulphated tri- to penta-saccharides released by alkaline-borohydride treatment of the proteoglycan glycopeptides. The oligosaccharides were fractionated by ion-exchange chromatography and gel filtration, and their structural properties were studied by methylation analysis and fast-atom-bombardment mass spectrometry. Five fractions containing [35S]sulphate-labelled oligosaccharides were obtained by ion-exchange chromatography, each of which was eluted from Sephadex G-50 as two well-separated peaks. The apparent Mr values of both the large- and small-molecular-size fractions increased with increasing acidity (and sulphate labelling) of the oligosaccharides. The larger-molecular-size fractions contained short mannose-linked keratan sulphate chains of Mr 3000-4500, together with some asparagine-linked oligosaccharides. The smaller tri- to penta-saccharides, of Mr 800-1400, appear to have a common GlcNac(beta 1-3)Manol core, and to contain one to two residues of sialic acid and/or sulphate.

Acetylglucosamine↗
PubMed1987

Identification and synthesis of a recognition signal for the attachment of glycosaminoglycans to proteins.

Comparison of the amino acid sequences of three different proteoglycan core proteins reveals a 12-amino acid sequence that is about 50% homologous among these proteoglycans. In each of the proteoglycans, this sequence surrounds the serine-glycine dipeptide in which the serine is known or presumed to be substituted with a chondroitin/dermatan sulfate glycosaminoglycan chain. Peptides containing this sequence from two proteoglycans were examined for their ability to serve as acceptors for xylosyltransferase, the enzyme that begins the assembly of glycosaminoglycan chains. Those peptides corresponding to amino acid sequences known to contain glycosaminoglycan-substituted serine residues in the protein were efficient xylosyltransferase acceptors, whereas peptides from sequences with no glycosaminoglycan-substituted serine residues were not. Amino acid substitutions at four critical sites in the acceptor peptides showed that single substitutions could completely abolish acceptor activity or greatly reduce it. The results suggest that the proteoglycan recognition consensus sequence for the attachment of glycosaminoglycans to core proteins consists of acidic amino acids closely followed by the tetrapeptide Ser-Gly-Xaa-Gly, where Xaa is any amino acid. The signal appears to be contained in the primary sequence information. In this regard it resembles a number of other signals for protein processing and intracellular routing.

Amino Acid Sequence↗
PubMed1986

Identification of an O-glycosidic mannose-linked sialylated tetrasaccharide and keratan sulfate oligosaccharides in the chondroitin sulfate proteoglycan of brain.

The chondroitin sulfate proteoglycan of rat brain was digested with Pronase, and after removal of glycosaminoglycans, the resulting glycopeptides were treated with alkaline borohydride to release O-glycosidically linked oligosaccharides. These were fractionated by ion exchange chromatography, gel filtration, and preparative thin layer chromatography, and their structural properties were studied by specific enzymatic degradations, methylation analysis, and gas-liquid chromatography-mass spectrometry of disaccharides as their trimethylsilylated and permethylated derivatives. In addition to the previously characterized N-acetyl-galactosamine-linked oligosaccharides and neutral mannitol-containing oligosaccharides [GlcNAc(beta 1-3) Manol and Gal(beta 1-4)[Fuc(alpha 1-3)]GlcNAc(beta 1-3)Manol] (where Fuc is fucose), we have now identified the sialylated tetrasaccharide NeuAc(alpha 2-3)Gal(beta 1-4)GlcNAc (beta 1-3)Manol, which accounts for approximately 20% of the mannitol-containing oligosaccharides. The proteoglycan also contains mannose-linked keratan sulfate chains (with a molecular size of 3,000 to 10,000 Da) composed of disaccharide repeating units consisting of Gal(beta 1-4)GlcNAc-6-O-SO4(beta 1-3), with a small proportion of branch points at C-6 of galactose residues. There is approximately one keratan sulfate chain per four chondroitin sulfate chains of 18,000-19,000 Da. After alkaline borohydride treatment of the neutral and monosialyl glycopeptide fractions, the combined decrease in mannose and N-acetylgalactosamine was very close to the observed destruction of serine + threonine and was accompanied by an equimolar increase in alanine and alpha-aminobutyric acid. One half of the mannose was destroyed by alkaline borohydride treatment of the glycopeptides and stoichiometrically converted to mannitol, while there were only small changes in the relative amounts of the other sugars and amino acids. The data demonstrate that over half of the carbohydrate-peptide linkages in the proteoglycan are of the mannosyl-O-serine/threonine type.

Animals↗