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Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the ability of two filarial species, Onchocerca volvulus and Brugia malayi, to solubilize collagen molecules from native collagen fibrils. Collagenolytic activity was detected in extracts of adult worms, in living microfilariae of O. volvulus and in live infective larvae and adult female worms of B. malayi. Excretion-secretion factors produced in vitro by infective larvae of B. malayi also contained large amounts of collagenase. Studies with enzyme inhibitors suggest that the latter may be a metallo-protease. Antibodies to filarial collagenase were present in sera from patients with onchocerciasis and brugian filariasis and from mice immunized with B. malayi. These antibodies and a monoclonal antibody raised against O. volvulus antigens immunoprecipitate filarial collagenase but appear not to be directed against the active site of the enzyme.
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PMID:Studies on a filarial antigen with collagenase activity. 242 72

Adults of Onchocerca volvulus and Onchocerca gibsoni were identically fractionated into a surface-enriched fraction, a phosphate buffered saline (PBS) extract and a PBS insoluble-detergent soluble fraction. Glycoproteins were prepared from these extracts and all fractions were examined by the Western blot technique using sera from individuals infected with a variety of filarial and non-filarial nematode worms. Using antisera to O. volvulus, a number of antigens were demonstrated in all of the extracts, with some antigens of each extract being unique. Many antigens were glycoproteins, and a high cross-reactivity was observed between O. volvulus and O. gibsoni. The different fractions of both species were also analysed using a panel of different sera in order to identify Onchocerca-specific antigens. The studies revealed that the lower molecular weight antigens showed greater Onchocerca specificity in all of the extracts examined. The surface-enriched fraction, however, clearly contained less widely cross-reacting components than the somatic and glycoprotein fractions. Finally, using surface labelling and coprecipitation techniques, O. gibsoni was shown to possess a 20 kDa Onchocerca-specific antigen, previously described for O. volvulus. The findings indicate a number of Onchocerca-specific antigens which may have potential in diagnosis of human onchocerciasis. They also show that the related bovine parasite O. gibsoni, may be an alternative source of material.
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PMID:Identification of antigens of Onchocerca volvulus and Onchocerca gibsoni for diagnostic use. 242 80

A surface enriched fraction was prepared from adults of Onchocerca volvulus by brief extraction of entire worms with detergent. This was then gel filtered to yield a low molecular weight fraction which functioned specifically in ELISA analysis. An identical result was also obtained when the related cattle parasite, O. gibsoni, was similarly fractionated and tested. The low molecular weight fraction contained at least four antigenic components when examined by coprecipitation and immunoblotting studies. One ml of packed worms yielded sufficient low molecular weight antigen to examine about 2,000 human sera by the ELISA procedure, and the test was sensitive at human serum dilutions down to 1/400. A preliminary study with individual sera from Onchocerciasis endemic and non-endemic areas of Southern Mexico yielded 0/24 false positives, 3/24 false negatives and a significant ELISA value in 21/24 sera from proven cases of Onchocerciasis.
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PMID:Isolation of an antigenic fraction for diagnosis of onchocerciasis. 243 30

Adult Onchocerca volvulus were isolated from nodules removed from onchocerciasis patients at four locations--two in the West African Sudan-savanna region (near Bamako, Mali, and Touboro, Cameroon), one in a West African forest region (Kumba, Cameroon) and one near Guatemala City, Guatemala. Four different cDNA expression libraries were constructed in bacteriophage lambda gt11 using poly(A)+ RNA from the adult female worms. Individual cDNA clones of single copy genes were used to compare the genomes of parasites from the different locales and to show that the haploid genome of O. volvulus is 1.5 x 10(8) base pairs. About 1 in 700 recombinant clones in each of the four amplified cDNA libraries produces a fusion protein recognized by pooled human anti-O. volvulus antisera. Partial sequence determination of a 2.0 kb cDNA clone for an O. volvulus protein that induces an immunodominant response in rabbits revealed that this antigen has sequence similarities with Caenorhabditis elegans myosin and with schistosome paramyosin (which confers partial protection against schistosome infection). The four cDNA libraries have been deposited with American Type Culture Collection (ATCC), 12301 Parklawn Drive, Rockville, MD 20852, U.S.A., for general distribution under ATCC Number 37509.
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PMID:Construction of Onchocerca volvulus cDNA libraries and partial characterization of the cDNA for a major antigen. 246 64

The cDNA synthesized from mRNA of Dirofilaria immitis female adult worms was cloned into the expression vector lambda gt11. Screening the library with a hyperimmune rabbit antiserum raised against adult worm homogenates yielded several antigen positive clones. One of these clones, lambda cDi2, was recognized by rabbit antisera raised against either D. immitis L-3, adult, Brugia malayi L-3 or Onchocerca volvulus adult worm antigen, as well as by antisera from humans naturally infected with O. volvulus or Wuchereria bancrofti. Affinity-purified anti-lambda cDi2 antibodies reacted with a 97-kDa protein on Western transfers of adult D. immitis antigen extracts that were reduced with beta-mercaptoethanol. The whole rabbit anti-D. immitis adult antiserum depleted of anti-lambda cDi2 antibodies exhibited decreased reactivity to this 97-kDa band. A monoclonal antibody (IA6) that specifically binds Schistosoma mansoni paramyosin also recognised a 97-kDa protein in D. immitis extracts upon Western transfer. The deduced amino acid sequence of partial DNA sequence from lambda cDi2 showed some similarity to nematode myosin, and gave a stretch of 82 amino acids that is 91.5% identical to Caenorhabditis elegans paramyosin: thus, lambda cDi2 encodes D. immitis paramyosin.
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PMID:A lambda gt11 cDNA recombinant that encodes Dirofilaria immitis paramyosin. 252 35

The suitability of motility indices and tetrazolium-based colorimetric assays for the determination of the viability of adult Onchocerca volvulus after in vitro exposure to potential macrofilaricides has been examined. Experimentation showed that both techniques could be applied to adult O. volvulus, although the variability between individual worms necessitated the use of large experimental groups. The potential of using cut anterior tips of female O. volvulus for screening was also investigated. These were shown to give reasonably consistent motility indices, and drug effects were discernible even after 72 h in vitro culture. Application of these viability criteria to studies on the short-term in vitro survival of intact male and female O. volvulus incubated in Eagles MEM plus serum, under 5% CO2 in air, showed this medium to be suboptimal with a greater than 50% loss of worm viability within 144 h of nodulectomy. Males isolated by the collagenase technique were shown to be significantly less viable than dissected males, by both motility indices and tetrazolium reduction. The results highlight the need to use either dissected males, or in the case of females, the need to minimize exposure to collagenase solution. A possible mechanism for selecting a more uniformly viable female worm population is discussed. Examination of the in vitro effects of CGP 20376 using these viability criteria/assay systems showed some delayed suppression of worm motility, but after 120 h in vitro CGP 20376 was not macrofilaricidal against male or female O. volvulus. Male worms were also implanted subcutaneously into gerbils.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A preliminary assessment of the feasibility of evaluating promising antifilarials in vitro against adult Onchocerca volvulus. 255 38

Experiments have confirmed that MTT-formazan colorimetry in its simplest form (incubation of intact worms with MTT and direct visualisation of any formazan formed) can be readily applied to several species of filariae including Onchocerca volvulus. Data is presented which will assist the development of quantitative MTT reduction viability tests for a selection of the smaller filarial species. Assays of pieces of Onchocerca gutturosa and O. volvulus females have led us to tentatively conclude that the tips of filariae, particularly the anterior ends, may well be metabolically the most active part of the worm. Selective sampling of these regions for Onchocerca might therefore be a useful indicator for the viability of the parasite. An example of how MTT-formazan colorimetry has been applied to yield additional data to support motility observations on the in vitro survival of male O. gutturosa is also given. The in vitro timecourse of worm death caused by 10 microM CGP 20376 on Acanthocheilonema viteae females has been examined by MTT reduction and compared with 6 other non-subjective parameters. The results suggests that the parameters examined could be divided into two groups according to the time taken for CGP 20376 to cause 50% inhibition (t50) of the parameter. Fast response parameters had t50's between 1 and 6 h (motility indices, 14CO2 evolution, adenine uptake and leucine uptake), they are more sensitive measures of viability and indicate possible worm damage which may or may not be reversible. Slow response parameters had t50's between 34 and 48.5 h (lactate output, MTT reduction and adenine leakage), and are probably linked with severe degenerative changes and are indicative of worm death.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The further application of MTT-formazan colorimetry to studies on filarial worm viability. 261 39

The viability and drug responses of cryopreserved adult Onchocerca have been examined in vitro. Male worms were cryopreserved in liquid nitrogen (-196 degrees C) using ethanediol as a cryoprotectant in a 2-step incubation procedure. After thawing, 85-90% of O. gutturosa males were normally motile. These motile worms were evaluated for viability using 4 measurements (long-term motility/survival in culture; [U-14C]adenine uptake and leakage; glucose utilization; MTT-formazan colorimetry) and were no different from unfrozen controls. Subsequent experiments demonstrated that the motility responses of cryopreserved worms exposed to the antifilarial drugs ivermectin, CGP 6140 and levamisole were virtually identical to unfrozen controls. Some success was also obtained with this technique in cryopreserving O. volvulus males, with 2 thawed specimens surviving in culture for 93 and 106 d respectively. Following collagenase isolation, female worms were cryopreserved in medium +10% serum without protectant at -79 degrees C. A batch of 8 female O. gutturosa were all motile when thawed 14 d later, with a mean survival time (based on 5 specimens) of 71 d (range 60-90). However, a batch of worms transferred from -79 degrees C to -196 degrees C were badly damaged when thawed. Female O. volvulus were cryopreserved at -79 degrees C in Guatemala and sent by air freight on solid CO2 to the UK. Most specimens were active when thawed. Survival of motile specimens ranged from 7 to 272 d in culture. It is concluded that these techniques are of practical value for the storage and transportation of adult Onchocerca.
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PMID:Onchocerca gutturosa and O. volvulus: studies on the viability and drug responses of cryopreserved adult worms in vitro. 261 29

Free ecdysteroids were detected in Onchocerca gibsoni, in tissues constituting O. volvulus and O. gibsoni nodules and in unrelated bovine tissues. Ecdysone and 20-hydroxyecdysone were identified by HPLC-RIA and GC/MS(SIM). The concentration of free ecdysteroids in the nodule tissue immediately surrounding the parasites was at least an order of magnitude higher than that detected in the worms themselves, or in adjacent nodular tissues or other bovine tissues.
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PMID:Analysis of ecdysteroids in Onchocerca gibsoni, O. volvulus and nodule tissues. 262 26

A new procedure is described which enables gram quantities of adult Onchocerca tissue to be isolated from frozen connective tissue nodules, thus minimizing the risk of enzymatic degradation. Bovine connective tissue nodules containing adult Onchocerca gibsoni worms were obtained from Australia frozen at -70 degrees C and sectioned while still frozen into 3 mm thick slabs. The sections were thawed immediately before use, worm segments removed, rinsed, pelleted, and flash frozen in liquid nitrogen. Quality of the isolated material was demonstrated by the presence of an intact adult epicuticle as determined by electron microscopy, and by the presence of viable uterine larvae and cells. This procedure is applicable to other nodule-forming worms such as Onchocerca volvulus and is suitable for investigations which require the isolation of labile molecules or those present in minute quantities.
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PMID:Isolation of Onchocerca gibsoni tissue from frozen nodules for biochemical use. 263 68


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