Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Circulating immune complexes were detected in sera of patients with both localized and generalized onchocerciasis by a 125I-Clq binding assay but not by the IgG latex agglutination inhibition method. Gel filtration of sera demonstrated high molecular weight Clq-reactive material(greater than 2 x 10(6) Daltons) which contained IgM but no IgG. Antibody titres to Onchocerca volvulus antigen were higher in patients with generalized disease than in those with the localized form. The lack of correlation between antibody titres and levels of immune complexes suggests that these immune complexes contain antigens other than those derived exclusively from the parasite. Although few of the symptoms of this disease are likely to be due to deposition of circulating immune complexes, the depression of delayed hypersensitivity reactions to the parasite found in patients with generalized onchocerciasis may be due to IgM immune complexes exerting an immuno-regulatory role on T cell function.
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PMID:Circulating immune complexes in onchocerciasis. 737 29

Onchocerca volvulus is a pathogenic human filarial parasite which, like other helminth parasites, is capable of evading the host's immune responses by a variety of defense mechanisms which are likely to include the detoxification and repair mechanisms of the enzyme glutathione S-transferase (GST). In this study, we show that one of the previously described GSTs from O. volvulus appears to possess the characteristics of a secreted enzyme. When the complete O. volvulus GST1 (OvGST1) sequence presented here is compared with those of other GSTs, 50 additional residues at the N terminus are observed, the first 25 showing characteristics of a signal peptide. This is consistent with the N-terminal sequence data on the native mature enzyme which begins at amino acid 26, based on the deduced protein sequence from the cDNA. The native protein, without the signal peptide sequence, possesses a 24-amino-acid extension not present in other GSTs. The deduced amino acid sequence of the OvGST1 cDNA clone was shown to possess four potential N-glycosylation sites. Digestion of O. volvulus homogenate with endoglycosidase, followed by detection of OvGST1 with specific antibody, indicated that the enzyme possesses at least two N-linked oligosaccharide chains. Gel filtration of the Escherichia coli-produced recombinant OvGST1 showed that it is enzymatically active as a nonglycosylated dimer. OvGST1 is found in the media surrounding adult worms maintained in culture, indicating that, in vitro, this enzyme is released from the worm. The strongest immunostaining for OvGST1 was observed in the outer cellular covering of the adult worm body, the syncytial hypodermis, especially in the interchordal hypodermis, where the peripheral membrane forms a series of lamellae which run into the outer zone of the hypodermal cytoplasm.
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PMID:A novel type of glutathione S-transferase in Onchocerca volvulus. 792 52

Complete cDNA and genomic sequences encoding the Onchocerca volvulus S-adenosylmethionine decarboxylase (SAMDC), a key enzyme in polyamine biosynthesis, have been isolated and characterized. The deduced amino acid sequence encodes a 42 kDa proenzyme with a moderate level of sequence homology to eukaryotic SAMDCs. Enzymically active O. volvulus SAMDC was expressed at a high level in an Escherichia coli mutant strain lacking endogenous SAMDC. The recombinant enzyme was purified to homogeneity using DEAE-cellulose, methylglyoxal bis(guanylhydrazone)-Sepharose and Superdex S-200 chromatography. It was determined that the recombinant proenzyme is cleaved to produce 32 and 10 kDa subunits. The sequence of the N-terminal portion of the large subunit was determined and comparison with the sequence of the proenzyme revealed that the precise cleavage site lies between Glu86 and Ser87. Gel-filtration experiments demonstrated that these two subunits combine to form an active heterotetramer. Comparison of the cDNA and genomic sequences revealed that the SAMDC mRNA undergoes both cis- and trans-splicing in its 5'-untranslated region (UTR). Anchored PCR on O. volvulus mRNA confirmed the cDNA sequence and identified two distinct trans-spliced products, a 22-nucleotide spliced-leader sequence and a 138 bp sequence containing the 22 nucleotide spliced-leader sequence. Genomic Southern-blot analysis suggests that the O. volvulus SAMDC is encoded by a single-copy gene. This gene spans 5.3 kb and is comprised of nine exons and eight introns. The first intron is located in the 5'-UTR and processing of this intron has a potential regulatory function. The 5'-flanking region of the gene contains potential transcriptional regulatory elements such as a TATA box, two CAAT boxes and AP-1-, C/EBP-, ELP-, H-APF-1-, HNF-5- and PEA3-binding sites.
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PMID:A novel trans-spliced mRNA from Onchocerca volvulus encodes a functional S-adenosylmethionine decarboxylase. 897 61

Glyoxal, methylglyoxal and other physiological alpha-oxoaldehydes are formed by the lipid peroxidation, glycation and degradation of glycolytic intermediates. They are detoxified enzymically by the glyoxalase system. To investigate the physiological function of glyoxalase I in parasitic organisms, the cDNA for glyoxalase I from the filarial nematode Onchocerca volvulus (designated Ov-GloI) has been cloned and characterized. The isolated cDNA contains an open reading frame of 579 bp encoding a protein with a calculated molecular mass of 21930 Da. Owing to the high degree of sequence identity (60%) with human glyoxalase I, for which the X-ray structure is available, it has been possible to build a three-dimensional model of Ov-GloI. The modelled core of Ov-GloI is conserved compared with the human glyoxalase I; however, there are critical differences in the residues lining the hydrophobic substrate-binding pocket of Ov-GloI. A 22 kDa protein was obtained by heterologous expression in Escherichia coli. A homogeneous enzyme preparation was obtained by affinity purification and functional characterization of the recombinant enzyme included the determination of kinetic constants for methylglyoxal and phenylglyoxal as well as inhibition studies. Gel filtration demonstrated a dimeric structure. To assess the role of Ov-GloI as a potential vaccine candidate or serodiagnostic tool, the serological reactivity of the recombinant Ov-GloI was analysed with sera from microfilaria carriers and specific IgG1 antibodies were detected. The effects of oxidative insult, namely plumbagin and xanthine/xanthine oxidase, on the gene transcript level of Ov-GloI were investigated. By using a semi-quantitative PCR ELISA it was shown that Ov-GloI is expressed at elevated levels under conditions of oxidative stress.
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PMID:A stress-responsive glyoxalase I from the parasitic nematode Onchocerca volvulus. 1117 Oct 39