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Biomedical subjects

G Husby

Publications and source records attributed to G Husby.

At least 109 records · Page 6Linked to original sources

Rabbit serum amyloid protein A: expression and primary structure deduced from cDNA sequences.

Serum amyloid A protein (SAA), the precursor of amyloid protein A (AA) in deposits of secondary amyloidosis, is an acute phase plasma apolipoprotein produced by hepatocytes. The primary structure of SAA demonstrates high interspecies homology. Several isoforms exist in individual species, probably with different amyloidogenic potential. The nucleotide sequences of two different rabbit serum amyloid A cDNA clones have been analysed, one (corresponding to SAA1) 569 base pairs (bp) long and the other (corresponding to SAA2) 513 bp long. Their deduced amino acid sequences differ at five amino acid positions, four of which are located in the NH2-terminal region of the protein. The deduced amino acid sequence of SAA2 corresponds to rabbit protein AA previously described except for one amino acid in position 22. Eighteen hours after turpentine stimulation, rabbit SAA mRNA is abundant in liver, while lower levels are present in spleen. None of the other extrahepatic organs studied showed any SAA mRNA expression. A third mRNA species (1.9 kb) hybridizing with a single-stranded RNA probe transcribed from the rabbit SAA cDNA, was identified. SAA1 and SAA2 mRNA were found in approximately equal amounts in turpentine-stimulated rabbit liver, but seem to be coordinately decreased after repeated inflammatory stimulation.

Amino Acid Sequence↗

High molecular weight glycosaminoglycans in AA type amyloid fibril extracts from human liver.

Glycosaminoglycans have previously been identified in extracts of AA type hepatic amyloid fibril from a patient with amyloidosis associated with juvenile rheumatoid arthritis. The macromolecular properties of these polysaccharides are described here in more detail. By gel filtration and ion exchange chromatography glycosaminoglycans in the form of high molecular weight free chains were shown to coisolate with water extracted amyloid fibrils. About 60% of these were characterised as galactosamines (chondroitin sulphate/dermatan sulphate), whereas the remaining 40% consisted of N-sulphated glucosamines (heparin/heparan sulphate). The amyloid associated glycosaminoglycans were not part of intact proteoglycans in the fibril extracts.

Amyloidosis↗

Peripheral neuropathy in systemic lupus erythematosus.

We studied 33 consecutive patients with systemic lupus erythematosus (SLE) for neuropathy by employing the Neuropathy Symptom Score (NSS), Neurological Disability Score (NDS), EMG and nerve conduction velocity (NCV) studies, and determinations of vibration thresholds (VT). Polyneuropathy defined as NCV abnormalities of two or more nerves occurred in seven patients (21%). Neuropathic symptoms showed a poor correlation with NCV and VT, while clinical neuropathic signs, VT, and NCV correlated with each other in most instances. When reporting frequencies of neuropathy in SLE, NCV studies should be used as a basis. NSS, NDS, and VT give additional quantifiable information and can be useful in the follow-up of patients and for evaluating the response to therapy.

Adolescent↗

Identification of glycosaminoglycans in human renal and splenic secondary AA amyloid fibril preparations.

The evidence that glycosaminoglycans (GAGs) are specifically associated with amyloid, is strong. In the present study we looked for GAGs in water extracts of amyloid fibrils from kidney and spleen laden with AA amyloid secondary to ankylosing spondylitis. Significant amounts of high molecular weight GAGs were isolated from the fibril preparations of both organs using ion-exchange chromatography and gel filtration procedures. The polysaccharides present in purified human renal and splenic amyloid fibril material were characterized as follows: a) Sulphated GAGs of high molecular weight were found in both renal and splenic amyloid fibril extracts, but not in extracts from corresponding normal tissues. b) All of the renal amyloid-associated high molecular weight GAGs were chondroitin sulphate/dermatan sulphate, whereas splenic amyloid-associated high molecular weight GAGs had a chondroitin sulphate/dermatan sulphate:heparan sulphate ratio of approximately 2:1. c) The findings gave no evidence that GAGs coisolated with AA amyloid fibrils were parts of intact proteoglycan molecules with several GAG chains.

Adult↗

Muscular weakness in systemic lupus erythematosus.

We systematically evaluated muscular weakness in a series of patients with systemic lupus erythematosus (SLE) using standardized neurological scoring systems, namely Neuropathy Symptom Score for symptoms, and Neurological Disability Score for signs. Symptoms of weakness were statistically associated with clinical and electrophysiological evidence of nerve and muscle disease. Signs of weakness were statistically associated with malaise, disease activity, anemia, age, and raised erythrocyte sedimentation rate. Various disease associated variables influenced symptoms and signs differently. It is important to define a baseline characterizing muscular weakness in SLE before conclusions are drawn regarding its significance and prevalence.

Adolescent↗

[Central nervous symptoms and findings in patients with systemic lupus erythematosus].

Systemic lupus erythematosus is a disease characterized by multiple autoimmune phenomena, and a broad clinical spectrum. Involvement of the central nervous system is common, and in the majority of patients occurs mainly as an organic brain syndrome or as migraineous headache. Cerebral atrophy as judged by CT scan is common. Cerebral infarction occurs in a minority of patients, mainly those with high disease activity and a high titer of anti-phospholipid antibodies. Systemic lupus erythematosus should be considered as a possible diagnosis in patients with certain central nervous system aberrations, especially young females.

Adult↗

[Neuromuscular symptoms and findings in systemic lupus erythematosus].

Systemic lupus erythematosus (SLE) gives rise to a variety of autoimmune and clinical phenomena in a multisystem manner. Both the central and peripheral nervous systems are involved as well as skeletal muscle. Based on our work with SLE patients, we describe the different categories of peripheral neuropathy and myopathy. We suggest that the disease be considered as a possible diagnosis, especially when evaluating women with symptoms and signs of neuromuscular abnormalities.

Electromyography↗

Mink serum amyloid A protein. Expression and primary structure based on cDNA sequences.

The nucleotide sequences of two mink serum amyloid A (SAA) cDNA clones have been analyzed, one (SAA1) 776 base pairs long and the other (SAA2) 552 base pairs long. Significant differences were discovered when derived amino acid sequences were compared with data for apoSAA isolated from high density lipoprotein. Previous studies of mink protein SAA and amyloid protein A (AA) suggest that only one SAA isotype is amyloidogenic. The cDNA clone for SAA2 defines the "amyloid prone" isotype while SAA1 is found only in serum. Mink SAA1 has alanine in position 10, isoleucine in positions 24, 67, and 71, lysine in position 27, and proline in position 105. Residue 10 in mink SAA2 is valine while arginine and asparagine are at positions 24 and 27, respectively, all characteristics of protein AA isolated from mink amyloid fibrils. Mink SAA2 also has valine in position 67, phenylalanine in position 71, and amino acid 105 is serine. It remains unknown why these six amino acid substitutions render SAA2 more amyloidogenic than SAA1. Eighteen hours after lipopolysaccharide stimulation, mink SAA mRNA is abundant in liver with relatively minor accumulations in brain and lung. Genes encoding both SAA isotypes are expressed in all three organs while no SAA mRNA was detectable in amyloid prone organs, including spleen and intestine, indicating that deposition of AA from locally synthesized SAA is unlikely. A third mRNA species (2.2 kilobases) was identified and hybridizes with cDNA probes for mink SAA1 and SAA2. In addition to a major primary translation product (molecular mass 14,400 Da) an additional product with molecular mass 28,000 Da was immunoprecipitable.

Amino Acid Sequence↗

Antibodies to the peptide from the plasmid-coded Yersinia outer membrane protein (YOP1) in patients with ankylosing spondylitis.

Seventy-five Norwegian patients with ankylosing spondylitis (AS) were studied for class-specific antibody response against synthetic peptide, P81, representing the sequence of plasmid-coded outer membrane protein of Yersinia (YOP1) containing four amino acid homology (TDRE) with HLA-B27 sequence. Ten (16.7%), five (8.3%) and seven (11.2%) of 60 male AS patients showed elevated anti-YOP1 P81 antibody of IgA, IgG, and IgM class, respectively, whereas for each isotype only one (4%) of 25 healthy male controls was positive. Differences were not observed between female patients and controls. In all isotypes, antibody-positive patients were more frequently found in patients with active disease. The anti-YOP1 P81 antibody levels of the patients were generally not correlated with the antibody levels against the peptide representing the hypervariable region of HLA-B27 (B27 peptide). However, in one patient the antibody was shown to react with both peptides by cross-inhibition analysis. Overall, it appears that any causal relationship between YOP1 and pathogenesis of AS is not strong. Immunogenicity and cross-reactivity of the YOP1 region encompassing the TDRE sequence particularly at the T cell level require further study.

Adhesins, Bacterial↗

Autoantibodies to the HLA-B27 sequence cross-react with the hypothetical peptide from the arthritis-associated Shigella plasmid.

We previously reported elevated serum antibody levels to a peptide representing the HLA-B27 polymorphic region (B27 peptide) in HLA-B27(+) ankylosing spondylitis (AS) patients. A plasmid (pHS-2) isolated from arthritogenic Shigella flexneri strains had been shown to encode an amino acid sequence homologous to HLA-B27. Rabbit antibody to this sequence (pHS-2 peptide) strongly cross-reacted with B27 peptide and, to a much lesser extent, with Klebsiella nitrogenase peptide. Serum antibody levels to pHS-2 peptide were studied in 160 spondylarthropathy patients. 12 of 115 (10.4%) AS patients, 2 of 45 (4.4%) patients with Reiter's syndrome or reactive arthritis as well as 6 of 147 (4.1%) normal controls were shown to have elevated anti-pHS-2 peptide antibodies. Antibody levels to B27 and pHS-2 peptides were significantly correlated in 134 HLA-B27(+) patients (r = 0.333, P less than 0.001). 13 of 15 affinity-purified anti-B27 peptide antibodies from patients strongly cross-reacted with pHS-2 peptide, whereas only 3 weakly cross-reacted to nitrogenase peptide. Leucine appeared to be a critical residue for this cross-reaction. AS patients' anti-B27 peptide antibodies reacted with HLA-B27 transfected L cells. These results may suggest that pHS-2 peptide more efficiently "mimics" B27 peptide than does nitrogenase peptide. Involvement of pHS-2 in pathogenesis of spondylarthropathy through molecular mimicry mechanisms requires further study.

Amino Acid Sequence↗

[Primary Sjögren's syndrome--more than a dry mouth and dry eyes].

Primary Sjögren's syndrome is an autoimmune disease mainly affecting exocrine glands. The cardinal symptoms are keratoconjunctivitis sicca and xerostomia, the sicca complex, in addition to extraglandular manifestations. The diverse clinical picture and the therapeutic aspect of the syndrome are discussed.

Autoimmune Diseases↗

[The antiphospholipid syndrome].

Coagulopathy leading to arterial and venous thrombosis is sometimes seen in patients with systemic lupus erythematosus (SLE). It is caused by antiphospholipid antibodies reacting with negatively charged phospholipid constituents of membranes and coagulation factors. The patients may also suffer from recurrent fetal loss and neurological manifestations, and may have intermittent thrombocytopenia and low serum concentration of complement factor C4. Patients without evidence of SLE or other immunological disorders may also exhibit this antiphospholipid antibody-associated thrombotic tendency. The patients are often young women, and it is important to be aware of this kind of coagulopathy, because it may take a most severe course in some of the persons affected.

Adult↗

Cross-reactive epitope with Klebsiella pneumoniae nitrogenase in articular tissue of HLA-B27+ patients with ankylosing spondylitis.

Synovial tissues from patients with ankylosing spondylitis or reactive arthritis were examined by an immunoperoxidase technique, using antisera to synthetic peptides representing antigens shared between HLA-B27.1 and Klebsiella pneumoniae nitrogenase. With either antiserum, all HLA-B27+ patients with synovial inflammation showed strong immunoperoxidase staining in synovial lining cells, vascular endothelium, and infiltrating inflammatory cells. These findings indicate that antigens showing cross-reactivity between HLA-B27.1 and Klebsiella nitrogenase epitopes are strongly expressed within inflamed synovial tissues of HLA-B27+ patients.

Arthritis↗

Interleukin-6 in synovial fluid from patients with arthritis.

Synovial fluid and serum from patients with rheumatoid arthritis, other inflammatory arthritides, and traumatic arthritis were assayed for the presence of interleukin-6 (IL-6) by means of an IL-6-dependent mouse hybridoma cell line. The cytokine was detected in all the samples of synovial fluid (range 50-22000 U/ml). IL-6 in synovial fluid was positively correlated (r = 0.58, P = 0.03) with the erythrocyte sedimentation rate in patients with inflammatory arthritis. In serum, the concentration of IL-6 was slightly elevated in some patients with rheumatoid arthritis. The results demonstrate that IL-6 is released into synovial fluid in joints affected by arthritis, and there appears to be an association between the levels of IL-6 and disease activity.

Adolescent↗

The primary structure of equine serum amyloid A (SAA) protein.

The complete amino acid sequence of equine serum amyloid A (SAA) was elucidated. The protein consists of 110 amino acid residues and contains an 8-amino acid residue insertion tentatively located between positions 69 and 70, as compared with human SAA. Microheterogeneities were detected at positions 16, 44, and 59, compatible with the existence of more than one SAA gene in the horse. This corresponds to the situation in man and mouse. Pronounced homology with SAA from man and several animal species was observed, thus confirming the conserved structure of this acute phase reactant and apoprotein of high-density lipoprotein (HDL).

Amino Acid Sequence↗

Electrophoretic study of proteins associated with pseudo-exfoliation syndrome.

Lens capsule and aqueous humour from cataractous eyes with and without pseudo-exfoliation syndrome have been studied by SDS-PAGE electrophoresis. Four cataractous lenses with and four without pseudo-exfoliation were used. The pseudo-exfoliation positive capsule revealed two polypeptides not present in the control material, and accordingly, these components were regarded to be pseudo-exfoliation specific. The molecular weight of the respective polypeptides was estimated to be 14,400 and 16,300. No marked differences were found between the pseudo-exfoliation positive and negative aqueous humours.

Aqueous Humor↗

Presence of glycosaminoglycans in purified AA type amyloid fibrils associated with juvenile rheumatoid arthritis.

Previous studies have strongly suggested an association between glycosaminoglycans and tissue deposits of amyloid. The present study was aimed at studying this association in purified preparations of hepatic amyloid fibrils obtained from human AA type secondary amyloidosis. Glycosaminoglycans were isolated by gradient ion exchange chromatography of purified amyloid fibrils treated with pronase. Degradation with specific enzymes identified the glycosaminoglycans as chondroitin sulphate, dermatan sulphate, and heparin/heparan sulphate. The total amount of glycosaminoglycans specifically coisolated with the amyloid fibrils was 15 micrograms/mg fibril weight. The presence of glycosaminoglycans in amyloid may play a part in the incorporation of structurally diverse protein precursors into amyloid fibrils of identical ultrastructure.

Amyloidosis↗