Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| molecular cloning and primary sequence of a cysteine protease expressed by haemonchus contortus adult worms. | we have cloned cdnas encoding a 35-kilodalton cysteine protease that is a major component of protective extracts isolated from blood-feeding haemonchus contortus adult worms. near full-length cdnas for the protease were isolated by immunoscreening an adult worm cdna expression library with a rabbit antiserum prepared against the protein eluted from preparative sds gels and by rescreening the library with oligonucleotide probes. the protein predicted from the nucleotide sequence of the cdnas and ... | 1990 | 2385265 |
| development and survival of haemonchus contortus larvae on pasture at vom, plateau state, nigeria. | the development and survival of the eggs of haemonchus contortus on pasture at vom were studied by depositing faecal pellets on grass plots over a period of 12 months. development and survival to the infective larvae occurred throughout the study except during the dry season months of december to april. more infective larvae were recovered from the herbage in june, july and august than in other months. the survival time of the infective larvae ranged from 2 weeks in october to 10 weeks in june, ... | 1990 | 2382405 |
| critical controlled test to evaluate resistance of field strains of haemonchus contortus to thiophanate. | following reports of suspected gastrointestinal strongylid nematode resistance to thiophanate in sheep and goats at sokoine university of agriculture (sua), tanzania, field strains of haemonchus contortus, one from sua and another from kimamba, tanzania, were selected for a critical controlled test to evaluate the efficacy of thiophanate. the sua h. contortus strain in goats showed a marked resistance to thiophanate at an oral dose of 50 mg kg-1 liveweight (efficacy = 24.1%), while the kimamba h ... | 1990 | 2382387 |
| seasonal changes and hypobiosis in haemonchus contortus infection in the west african dwarf sheep and goats in the nigerian derived savanna. | a survey was conducted in the nigerian derived savanna (from august 1987 to july 1988) on the seasonal fluctuations in the composition of haemonchus contortus burden of naturally infected west african dwarf sheep and goats. during this period 117 abomasa collected from locally slaughtered animals were processed. male, female as well as immature worms were enumerated. the incidence of haemonchus infection was high (77.8-100%) with no definite seasonal distinction. there was however, a clear seaso ... | 1990 | 2382380 |
| the effect of level of nutrition on the development of resistance to haemonchus contortus in sheep. | merino wether weaners, 5-months old at the start of the experiment and fed lucerne-based pellets at 600 g per head per day, developed resistance to haemonchus contortus given as a continuous or "trickle" infection at the rate of 500 larvae 3 times per week over a period of 17 weeks. by contrast, the development of resistance was impaired in weaners fed pellets at 400 g per head per day. low food intake and protein-energy deprivation, therefore, have a major effect in impairing the development an ... | 1990 | 2375712 |
| [principal helminths of small ruminants in ituri (upper zaire)]. | from august 1986 to november 1987, about 180 slaughtered sheep and goats were examined at bunia (haut-zaïre) in order to establish the main helminth parasites. seventeen and fifteen species were identified in sheep and goats respectively. the occurrence of stilesia hepatica, oesophagostomum multifoliatum and muellerius capillaris as well as the absence of echinococcus granulosus constituted the original features of this check-list in the area. parasitism the most frequently encountered both in s ... | 1990 | 2369171 |
| fenbendazole resistance in haemonchus contortus of sheep. | 1990 | 2368313 | |
| resistance by haemonchus contortus to ivermectin in angora goats. | 1990 | 2368307 | |
| immune exclusion of haemonchus contortus larvae in the sheep: effects on gastric mucin of immunization, larval challenge and treatment with dexamethasone. | the rapid expulsion of the gastric nematode haemonchus contortus from primed sheep is a complex mechanism which probably involves immediate hypersensitivity reactions and mucus. quantitative techniques were employed to determine the content and distribution of mucin in the gastric mucosae of sheep of varying immune status, following a single large challenge with h. contortus. substantial depletion of both neutral and acidic mucin, following challenge, was noted in the gastric mucosae of naive sh ... | 1990 | 2365855 |
| biochemical characterization of cuticle polypeptides from the infective larvae of haemonchus contortus. | 1. ecdysis of infective haemonchus contortus larvae is effected by the enzymatic degradation of a specialized region of the second molt cuticle containing a biochemically unique polypeptide (mol. wt = 160,000). 2. the 160,000 mol. wt polypeptide and related polypeptides are synthesized at approximately 6 days of larval development. antigenically similar polypeptides occur in other ruminant trichostrongyles. 3. cuticle polypeptides digested during ecdysis differ from second molt cuticle collagens ... | 1990 | 2361368 |
| effect of environmental stimuli on pre-infective and infective stages of haemonchus contortus in the northern united states for the induction of hypobiosis. | the effects of both natural and artificial conditioning of pre-infective and infective stages of haemonchus contortus were examined in two studies with 108 crossbred lambs, using an ohio isolate of h. contortus known to exhibit up to 100% winter hypobiosis. the intensity of hypobiosis varied from 0 to 36% in 17 lamb groups given larvae subjected to various temperature and photoperiod conditions. the results in lambs given larvae conditioned for 4-8 weeks were not significantly different from tho ... | 1990 | 2353422 |
| faecal water content and egg survival of goat gastro-intestinal strongyles under dry tropical conditions in guadeloupe. | faeces from naturally infected goats were deposited on a natural grassland during the dry season in guadeloupe (french west indies) at different times throughout the day. the grass was either 7 or 20-30 cm tall. after a period of between several hours and 7 days, the number of viable strongyle eggs and the faecal water content were measured. faecal temperature was recorded continuously. faecal temperature was greater than 40 degrees-45 degrees c at midday and dehydration was rapid between 8 a.m. ... | 1990 | 2352914 |
| anthelmintic activity of paraherquamide in sheep. | paraherquamide, an oxindole alkaloid metabolite of penicillium paraherquei, was tested against the common gastrointestinal nematode species of sheep at 0.25, 0.5, 1.0, and 2.0 mg/kg, per os. it was highly efficacious (greater than or equal to 98% reduction) as a single oral treatment dosages greater than or equal to 0.5 mg/kg against adult haemonchus contortus, ostertagia circumcincta, trichostrongylus axei, trichostrongylus colubriformis and cooperia curticei, and the l4 stage of cooperia spp. ... | 1990 | 2352063 |
| effect of selection pressure for thiabendazole resistance on fitness of haemonchus contortus in sheep. | a strain of haemonchus contortus showing moderate levels of resistance to thiabendazole (tbz) (egg hatch assay lc50 2.1 microm) was subjected, in alternating sequence, to 5 in vitro and 4 in vivo selections with tbz. this resulted in a significant increase in resistance (egg hatch assay lc50 2.8 microm). the isolates obtained after each combined in vitro and in vivo selection were compared in terms of egg hatch assay, establishment, net egg output, per capita egg output and degree of pathology c ... | 1990 | 2345665 |
| the establishment and development of haemonchus contortus in goats. | twelve goats were inoculated with 40,000 third-stage haemonchus contortus larvae and two were killed on each of days 4, 7, 11, 14, 18 and 21 after inoculation (dai). the number of worms that established, and the site of development were recorded. more worms established in the fundic, than in the middle or pyloric thirds of the abomasum. early development occurred within the mucosa; emergence into the lumen started between 7 and 11 days after infection. by 4 dai, all worms had completed the third ... | 1990 | 2343536 |
| a novel approach to the control of anthelmintic-resistant haemonchus contortus in sheep. | this paper reports attempts to control a resistant strain of haemonchus contortus on pasture by replacing it with a susceptible strain. by making use of artificially infected donor sheep, six camps (paddocks) were seeded with a resistant field strain of h. contortus until it was confirmed by means of worm-free tracer lambs that the grazing had become infective. thereafter, using donor sheep infected with a susceptible laboratory strain of h. contortus for seeding the pasture, attempts were made ... | 1990 | 2343532 |
| cryopreservation of some common nematodes of ruminants for up to 11,3 years. | infective larvae of selected batched of the following nematode species from sheep and cattle were examined for survival and infectivity (by injection into either the abomasum, the duodenum, or the jugular vein) after having been stored in liquid nitrogen for 103-136 months: haemonchus contortus, haemonchus placei, ostertagia circumcincta, ostertagia ostertagi, marshallagia marshalli, cooperia spp., trichostrongylus axei, trichostrongylus colubriformis, trichostrongylus falculatus, nematodirus sp ... | 1990 | 2338992 |
| closantel resistance in haemonchus contortus from sheep. | 1990 | 2334373 | |
| development and survival of infective larvae of haemonchus contortus and trichostrongylus colubriformis on pasture in a tropical environment. | a trial to determine the seasonal pattern of egg hatching and larval survival on pasture was carried out in representative wet and dry zones of fiji. fourteen plots were established on parasite-free pasture at each of two sites. one plot at each site was contaminated every month with faeces from naturally infected goats containing a known proportion of haemonchus contortus and trichostrongylus colubriformis eggs. pasture was sampled at regular intervals after contamination and infective larvae i ... | 1990 | 2332275 |
| specific interaction of benzimidazole anthelmintics with tubulin: high-affinity binding and benzimidazole resistance in haemonchus contortus. | the specific (high-affinity) binding of tritiated benzimidazole [(3h]bz) anthelmintics-mebendazole [(3h]mbz) and oxibendazole [(3h]obz) to, and the specific displacement (inhibition) of these radioligands by unlabelled bzs (oxibendazole, mebendazole, oxfendazole, albendazole, fenbendazole and thiabendazole) from crude tubulin extracts prepared from thiabendazole (tbz)-susceptible (s) or tbz-resistant (r) strains of adult haemonchus contortus, have been examined. the most striking difference betw ... | 1990 | 2325707 |
| scanning electron microscopy of the sheathed infective larva and parasitic third-stage larva of haemonchus contortus (nematoda: trichostrongyloidea). | scanning electron microscopy was used to describe the infective and parasitic third-stage larvae of haemonchus contortus, the large stomach worm of ruminants. infective larvae are ensheathed in the cuticle of the second stage, so the descriptions are of the second- and third-stage cuticles. both larval stages had an inner circle of 6 labial papillae, an outer circle of 6 labial papillae and 4 somatic papillae, and lateral amphidial pits. infective larvae (cuticle of the second stage) had the 6 i ... | 1990 | 2319426 |
| a novel anthelmintic model utilizing jirds, meriones unguiculatus, infected with haemonchus contortus. | currently, no in vivo laboratory model is available for evaluating anthelmintics against the important ruminant helminth haemonchus contortus. this report outlines a novel anthelmintic assay utilizing immunosuppressed (0.02% hydrocortisone in feed) jirds, meriones unguiculatus, infected with h. contortus. immunosuppressed jirds were inoculated with approximately 1,000 exsheathed infective larvae of h. contortus, treated per os on day 10 postinoculation (pi), and necropsied on day 13 pi. each sto ... | 1990 | 2319415 |
| pepsinogen types in worm-free sheep and in sheep infected with ostertagia circumcincta and haemonchus contortus. | pepsinogen isolated from the plasma of dorset wethers with abomasal burdens of ostertagia circumcincta was found to have the same proportions of three zymogen subtypes as that isolated from the plasma of merino wethers with abomasal burdens of haemonchus contortus. it appears that the underlying pathophysiological response which causes increased plasma pepsinogen concentrations during abomasal parasitism may be the same irrespective of the breed of sheep or species of parasite. | 1990 | 2300702 |
| influence of dietary protein on the immune responsiveness of sheep to haemonchus contortus. | twenty helminth-free lambs were fed diets containing either 169 g crude protein (cp) kg-1 dry matter (dm) or 88 g cp kg-1 dm from the age of seven months. one month later five lambs from each dietary group were vaccinated against haemonchus contortus by the oral administration of 10,000 irradiated larvae on two occasions, four weeks apart. four weeks following the administration of the second dose of irradiated larvae both the vaccinated and unvaccinated lambs were exposed to an experimental inf ... | 1990 | 2300701 |
| gastro-intestinal nematode infections in a goat breeding farm in north-western sri lanka. | faecal egg counts were used to study patterns of nematode infestation of adult female goats and their offspring according to season, pregnancy and lactation or age on a goat farm (n = 2000) in north-western sri lanka. average rainfall in the area is 825 mm and temperature is between 23 and 33 degrees c throughout the year. the only nematode species present on the farm were haemonchus contortus and oesophagostomum columbianum. in adult females the faecal egg output was not influenced by season an ... | 1990 | 2288007 |
| low susceptibility of the laboratory-reared afghan pika, ochotona rufescens rufescens to haemonchus contortus. | 1990 | 2280496 | |
| changes in liveweight gain, blood constituents and worm egg output in goats artificially infected with a sheep-derived strain of haemonchus contortus. | two groups of goats were dosed with 10,000 and 20,000 sheep-derived strain (sds) larvae of haemonchus contortus respectively. over a period of 42 days goats dosed with 20,000 larvae lost more weight than those dosed with 10,000 larvae. infected goats showed anaemia from about 2 weeks after infection as well as reduced levels of total serum proteins and albumins. | 1990 | 2271911 |
| the efficacy of netobimin against a benzimidazole susceptible and a resistant strain of haemonchus contortus in sheep in the netherlands. | netobimin was tested for efficacy against haemonchus contortus using 7 groups of 5 parasite-free lambs of six months age. the lambs in group 1 and 2 were infected with 10,000 larvae of a benzimidazole susceptible strain and those in groups 3-7 with the same dose of a resistant strain. the following treatment scheme was applied 21 days after infection: lambs in groups 2 and 4-7.5 mg kg-1 netobimin, in group 5-20 mg kg-1 netobimin, in group 6-5 mg kg-1 oxfendazole and in group 7--3.8 mg kg-1 alben ... | 1990 | 2270650 |
| strategies for detoxification of aldehydic products of lipid peroxidation in helminths. | crude extracts from a number of helminths including schistosoma intercalatum and fasciola hepatica were able to detoxify known aldehydic products of lipid peroxidation. a major route for alk-2-enal and alka-2,4-dienal detoxification in parasitic helminths was via glutathione conjugation and glutathione transferase appeared to be responsible for the activity. as yet uncharacterised nadph-linked systems may provide an important secondary pathway for detoxification of alk-2-enals and alka-2,4-diena ... | 1990 | 2270103 |
| biochemical and immunochemical characterization of 125i-labeled cuticle components of haemonchus contortus. | live haemonchus contortus developmental stages were radioiodinated and then subjected to a stepwise extraction procedure consisting of a buffer extract (with or without detergent) to solubilize putative surface-associated antigenic macromolecules, followed by a detergent/beta-mercaptoethanol (bme) extract to solubilize putative cuticle collagen proteins. a buffer-extracted iodinated 100-kda protein was present in the free-living, infective l3(2m) stage. this labeled protein was released during i ... | 1990 | 2270098 |
| the population biology of the free-living phase of haemonchus contortus. | a deterministic model for the demography of the free-living stages of haemonchus contortus is described. the model consists of three compartments: the pre-infective stages, comprising the eggs and first- and second-stage larvae combined; third-stage larvae in the faeces; and third-stage larvae on the pasture. the mortality (mu j) of each of these stages was a function of temperature (k, where k = (degrees celsius + 30)/100) of the form, mu j = a j exp [alpha j k] + b j exp [-beta j k]. the minim ... | 1990 | 2263426 |
| [the nematode haemonchus contortus: antigenic characterization and immune response in rabbits and sheep]. | in the first part of the study, various tissues of l3 larvae and adult haemonchus contortus were examined by indirect fluorescence to investigate their antigenicity. l3 larvae were studied in immunoblots as well. the following tissues contained antigens: the sheath and cuticle of l3 larvae; and the cuticle, muscles, epithelium and glandular tissue of the oesophagus and sheath of the spicules of adult nematodes. on the cuticle of exsheathed l3 larvae, we detected by light-microscope slightly rais ... | 1990 | 2260078 |
| the epidemiology of helminthosis in small ruminants under the traditional husbandry system in eastern nigeria. | the epidemiology of helminth infections in west african dwarf sheep and goats under the traditional husbandry system prevailing in the derived savanna area of eastern nigeria was studied for 12 months. the infections observed were due to haemonchus contortus (87.1%), trichostrongylus spp. (63.8%), metacestodes of taenia hydatigena (30.2%), oesophagostomum columbianum (22.4%), strongyloides sp. (18.8%), cooperia spp. (17.2%), gaigeria pachyscelis (6.0%), moniezia expansa (6.0%), bunostomum trigon ... | 1990 | 2247944 |
| special problems of hair goats. | the majority of angora goats in the united states are in texas, although several other states have significant populations. angora goats have unique nutritional requirements, especially for protein, owing to their selection for mohair production. they are typically managed on extensive systems in which nutrition is marginal at certain times of the year. mineral requirements and plant toxicities may vary between regions where angora goats are raised. many toxic plants are unpalatable and a proble ... | 1990 | 2245371 |
| characterization of a high-affinity membrane-associated ornithine decarboxylase from the free-living nematode caenorhabditis elegans. | ornithine decarboxylase has been identified and characterized in the free-living nematode caenorhabditis elegans. unlike previously described ornithine decarboxylases, the enzyme activity is membrane-associated and remains in the membrane fraction after treatment with high salt, detergents or phosphatidylinositol-specific phospholipase c. ornithine has an apparent km value of 2.7 microm for ornithine decarboxylase. the enzyme is competitively inhibited by arginine and lysine with ki values of 4. ... | 1990 | 2241895 |
| anthelmintic activity of the macrocyclic lactone f28249-alpha in sheep. | the macrolytic lactone f28249-alpha was titrated in experimentally infected sheep and found to be highly effective against most of the common gastrointestinal nematodes as a single oral dose, given at a rate of 0.025, 0.05, or 0.1 mg/kg. specifically, maximal activity was evident at even the lowest dosage against adult haemonchus contortus, ostertagia circumcinta, trichostrongylus axei, and t colubriformis and l4 o circumcinta. activity against oesophagostomum columbianum was also high at all do ... | 1990 | 2240816 |
| is there a relationship between haemoglobin genotype and the innate resistance to experimental haemonchus contortus infection in merino lambs? | responses to a single or repeated infection with 7000 infective larvae of haemonchus contortus were studied in an experiment using a total of 106 3-month-old lambs with aa, ab or bb haemoglobin (hb) genotypes. results were assessed by faecal egg counts, adult worm counts, haematocrit values, haemoglobin concentrations, total serum protein and serum antibody igg1 and iga elisa titres. none of these parameters showed a strong relationship to the hb type. the prevalence of low responder (greater th ... | 1990 | 2238431 |
| absence of hypobiosis in abomasal nematodes of sheep and goats in egypt. | a total of 96 abomasa from sheep and goats at the zagazig abattoir, sharkia province, egypt, were examined, during the four climatic seasons from april 1986 to march 1987, for the presence of adult and larval nematodes. adults of trichostrongylus axei were most numerous followed by adult haemonchus contortus. adult ostertagia sp. and parabronema skrjabini were less prevalent. there was no significant difference between sheep and goats in infection rates, but worm burdens of the nematodes other t ... | 1990 | 2238430 |
| the seasonal epidemiology of gastrointestinal nematodes in n'dama cattle in the gambia. | from june 1987 to june 1988, a total of 180 n'dama cattle were necropsied to identify and enumerate parasites present, including 39 sick calves and 25 dead calves from local village herds, and 116 adult cattle from a local abattoir. of 175 animals infected with one or more helminths (97%), haemonchus contortus was found in 67% of all necropsied animals, cooperia punctata in 75%, cooperia pectinata in 55%, oesophagostomum radiatum in 71% and bunostomum phlebotomum in 21%. there was a wide range o ... | 1990 | 2238429 |
| efficacy of ivermectin against benzimidazole-resistant nematodes of sheep. | two trials involving a total of 36 dorset horn lambs were conducted to assess the anthelmintic efficacy of ivermectin against experimental infections of benzimidazole-resistant strains of haemonchus contortus and ostertagia circumcincta. two resistant strains of each of the two species were used and in each trial the lambs were allocated to three groups. one group was given 200 micrograms ivermectin/kg bodyweight orally, the second group was given 5 mg oxfendazole/kg bodyweight orally and the th ... | 1990 | 2238413 |
| a larval development test for the detection of anthelmintic resistance in nematodes of sheep. | first stage larvae of a number of species of parasitic nematodes of sheep have been shown to develop to third stage larvae in the presence of a defined medium consisting of earle's balanced salt solution and yeast extract. a larval development test, based on this culture technique, was used as a screen for detecting the presence of anthelmintic resistance in nematodes of sheep. it was found to be sensitive and simple to use and also appeared capable of detecting resistance to any of the main ant ... | 1990 | 2236917 |
| effect of copper oxide wire particle treatment on establishment of major gastrointestinal nematodes in lambs. | eighty-four 10-week-old lambs were used to investigate the effect of copper oxide wire particle treatment on the establishment of major gastrointestinal nematodes. they were maintained on pasture previously treated to minimise larval contamination. five grams of uniform sized copper oxide wire particles were given orally five days before infection with either 20,000 trichostrongylus colubriformis larvae, 20,000 ostertagia circumcincta larvae or 3000 haemonchus contortus larvae given as three dos ... | 1990 | 2236907 |
| tyrosine-derived cross-linking amino acids in the sheath of haemonchus contortus infective larvae. | the sheath or second-molt cuticle (2m) was isolated from in vitro exsheathed haemonchus contortus infective larvae (l3[2m]). acid hydrolysates of 2-mercaptoethanol (2me)-soluble and 2me-insoluble cuticular proteins were analyzed by high performance liquid chromatography for tyrosine-derived cross-linking amino acids. dityrosine and isotrityrosine were identified by their chromatographic behavior, absorbance spectra, and other chemical characteristics in both the 2me-soluble and 2me-insoluble fra ... | 1990 | 2213404 |
| studies on the presence and release of proteolytic enzymes (proteinases) in gastro-intestinal nematodes of ruminants. | the proteolytic activity of worm homogenates prepared from the third stage larval (l3) and adult stages of the ovine gastro-intestinal nematodes, nematodirus battus, ostertagia circumcincta, trichostrongylus colubriformis, trichostrongylus vitrinus and haemonchus contortus, and the rodent intestinal nematode, nippostrongylus brasiliensis, has been examined using the protein substrates azocasein, azocoll and elastin-orcein. activity detected in third stage larvae was usually higher than that obse ... | 1990 | 2185170 |
| strategies for vaccination against gastro-intestinal nematodes. | a great diversity of gastro-intestinal nematodes parasitise man and his animals. each nematode is antigenically highly complex with distinct developmental stages. the parasites occupy a range of niches in the host gut and have a variety of feeding habits. hosts have evolved only partially successful local immune responses. the host and parasite factors modulating these responses are described. strategies for vaccination are surveyed. it is argued that the best route to successful vaccines will b ... | 1990 | 2132697 |
| infection of immunosuppressed mice with the abomasal nematode parasite of ruminants, haemonchus contortus. | infective larvae of haemonchus contortus established in mice either immunosuppressed with the corticosteroid, dexamethasone, or the cytotoxic drug, cyclophosphamide, or treated with the histamine h2 inhibitor, cimetidine. infections persisted for as long as the immunosuppressive treatment (7 days) and growth of larvae was similar to that seen in sheep. virtually no larvae survived in untreated mice. accordingly, it would appear that adaptive immunity is an important barrier against primary infec ... | 1990 | 2121657 |
| efficacy of some commercial formulations of anthelmintics on haemonchus contortus and trichostrongylus columbianum. | the anthelmintic action of five commercially formulated anthelmintics: assiazine, banminth, nemafax, piperazine and levamisole has been evaluated by observing the effect on egg hatch, motility and mortality of the larvae of trichostrongylus columbianum and haemonchus contortus. assiazine and levamisole inhibited egg-hatch of the helminth ova dose-dependently. nemafax, banminth, and piperazine did not inhibit egg hatch. levamisole and banminth affected the motility of the helminth larvae with sub ... | 1990 | 2093109 |
| a developmentally regulated cysteine protease gene family in haemonchus contortus. | the nucleotide sequence of a gene encoding a 35-kda thiol protease of the parasitic nematode haemonchus contortus has been determined. the gene, designated ac-2, shares 97% nucleotide sequence identity and 98% amino acid identity with previously characterized ac-1 cdnas encoding the thiol protease. the ac-2 gene spans 8 kb and appears to contain 11 introns, ranging in size from 57 bp to over 5.2 kb. one of the introns interrupts the proposed active site region that is conserved between the h. co ... | 1990 | 2090940 |
| effect of haemonchus contortus infection on the clearance of antipyrine, sulfobromophthalein, chloramphenicol, and sulfathiazole in lambs. | a study was made to determine the effect of haemonchus contortus parasitic infection in lambs on the clearance of several iv administered drugs. clearance of sulfobromophthalein or sulfathiazole from the plasma of lambs was unaffected by infection with h contortus. clearance of antipyrine was enhanced by the infection, and thiabendazole treatment did not alter this effect. clearance of chloramphenicol (cap), administered as the succinate ester (caps), was not changed by the infection, but it was ... | 1990 | 2085232 |
| the intensity of resistance by mature merino ewes against haemonchus contortus and trichostrongylus colubriformis in single-species and combined-species infection. | three-year-old, non-lactating and non-pregnant merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with haemonchus contortus, were given single-dose infections with either h. contortus or trichostrongylus colubriformis or both species together. the purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to i ... | 1990 | 2076067 |
| response to helminth infection of sheep selected for resistance to haemonchus contortus. | lines of merino sheep selected for increased (irh) and decreased (drh) resistance to haemonchus contortus were compared with an unselected (ch) line, after approximately four generations of selection. measurements were recorded on 69 irh, 47 drh and 84 ch animals. following artificial challenge with h. contortus, the irh line had significantly (p less than 0.001) lower faecal egg counts than the ch and drh lines (2730, 12,720 and 17,400 epg, respectively). significant differences (p less than 0. ... | 1990 | 2074125 |
| effect of development of resistance to benzimidazoles, salicylanilides and ivermectin on the pathogenicity and survival of haemonchus contortus. | two groups of six lambs were infected either with an anthelmintic-susceptible strain of haemonchus contortus or with a strain resistant to benzimidazoles, ivermectin and salicylanilides. the pathogenicity of the two strains of parasite was compared by monitoring the development of anaemia, changes in plasma proteins and abomasal damage in the two groups of lambs. there were no significant differences between the groups, suggesting that the development of resistance to several anthelmintics did n ... | 1991 | 2063534 |
| secretion and excretion of endogenously synthesized lipids by adult haemonchus contortus in vitro. | results of the incorporation of carbon from 14c-glycerol into total, polar and nonpolar lipids in haemonchus contortus (nematoda: trichostrongylidae) reveal that the radioactivity lost into the medium as lipids decreased during the first 3 h of incubation. this was followed by a drastic increase during the 4th h. again, there was a decline by 75% during the 5th h. however, there was a slight increase in the nonpolar lipids during the 5th h. | 1991 | 2050989 |
| fecundity of anthelmintic resistant adult haemonchus contortus after exposure to ivermectin or benzimidazoles in vivo. | a strain of haemonchus contortus resistant to the benzimidazoles, ivermectin and salicylanilides was used to study the effect of exposure to ivermectin or oxfendazole on the number of eggs produced by adult female parasites. after anthelmintic administration there was a reduction in the faecal egg count of the infected lambs. ivermectin caused a reduction in the number of eggs within adult parasites for up to 72 hours but this returned to higher than pre-treatment levels at 168 hours after treat ... | 1991 | 2034909 |
| utility of a haemonchus contortus/jird (meriones unguiculatus) model for studying resistance to levamisole. | trichostrongylid nematodes of sheep commonly are identified as exhibiting resistance to levamisole. in vitro assays have been developed to study levamisole resistance for haemonchus contortus, but no in vivo model has been identified for this species. to determine the utility of a h. contortus/jird (meriones unguiculatus) model for examining levamisole resistance, immunosuppressed jirds were inoculated with approximately 1,000 exsheathed infective larvae of h. contortus (resistant or susceptible ... | 1991 | 1992099 |
| specific interaction of benzimidazole anthelmintics with tubulin from developing stages of thiabendazole-susceptible and -resistant haemonchus contortus. | the low- and high-affinity binding of tritiated benzimidazole anthelmintics (mebendazole and oxibendazole) to tubulin-containing supernatants derived from unembryonated eggs, third stage larvae or adult worms of thiabendazole-susceptible and -resistant strains of haemonchus contortus were examined and compared. the displacement of these radioligands by unlabelled benzimidazoles (mebendazole, fenbendazole, thiabendazole and oxibendazole) also was examined. the binding affinity, k alpha, and maxim ... | 1991 | 1986746 |
| molecular analysis of selection for benzimidazole resistance in the sheep parasite haemonchus contortus. | the molecular basis for the resistance of the sheep parasitic nematode haemonchus contortus to the benzimidazole (bz) group of anthelmintics was investigated. three bz-susceptible and three resistant populations from different geographical locations were characterized with respect to the egg-hatch assay with thiabendazole (tbz), mebendazole (mbz) binding tests and restriction fragment length polymorphism (rflp) after southern blotting. cloned h. contortus alpha- and beta-tubulin genes were used ... | 1990 | 1981249 |
| resistance to benzimidazoles in haemonchus contortus of sheep in tanzania. | this study was undertaken to establish whether resistance to benzimidazole anthelmintics was present in gastrointestinal nematodes of sheep and goats at the university farm of sokoine university of agriculture, morogoro, tanzania. groups of lambs were treated with albendazole at 3.8 mg/kg (recommended dose rate), 5.6 mg/kg and 10.0 mg/kg and a fourth group was untreated. seven days after treatment, faecal egg count reductions (fecr) were found to be 94.3%, 97.6% and 99.3% and 14 days after treat ... | 1990 | 1980804 |
| the localization of somatostatin-like immunoreactivity in the alimentary tract of the sheep with observations on the effect of an infection with the parasite haemonchus contortus. | cells containing somatostatin immunoreactivity were localized in the alimentary tract of parasite-free sheep by indirect immunocytochemistry, using an antiserum raised to ovine somatostatin. nerve fibres showing somatostatin-like immunoreactivity were identified in the oesophagus, reticulum wall and groove, rumen pillar and wall, omasum sulcus and abomasum. varicose fibres were found in the myenteric plexuses of the duodenum, jejunum, ileum and colon. the greatest distribution of endocrine cells ... | 1990 | 1980195 |
| molecular biology of the cuticle collagen gene families of caenorhabditis elegans and haemonchus contortus. | 1990 | 1978527 | |
| a membrane associated glutamate binding protein from caenorhabditis elegans and haemonchus contortus. | 1. a glutamate binding protein has been identified in membrane preparations from the free living nematode, caenorhabditis elegans, and from the parasitic nematode, haemonchus contortus. 2. this putative glutamate receptor was solubilized with 30 mm octyl-b-glucoside and partially purified by anion exchange and gel filtration chromatography. 3. an 80-fold purification with recovery of 75% of the glutamate binding activity was achieved. 4. the soluble c. elegans binding protein displayed a kd for ... | 1990 | 1977551 |
| effect of nilzan and albendazole on the absorptive surfaces of haemonchus contortus (nematoda)--a histoenzymic study. | haemonchus contortus, incubated in 10 micrograms/ml and 50 micrograms/ml concentrations of nilzan and albendazole in tyrode solution were stained for histoenzymatic demonstration of various phosphatases, oxido-reductases and esterases. the intestine showed major alterations after drug treatments. the alkaline phosphatases (akpase), adenosine triphosphatase (atpase), glucose-6-phosphatase, succinic dehydrogenase (sdh), glutamate dehydrogenase (gdh), reduced nicotinamide adenine dinucleotide phosp ... | 1990 | 1963279 |
| efficacy of some anthelmintics on an ivermectin-resistant strain of haemonchus contortus in sheep. | following evidence of reduced efficacy of ivermectin in a field population of haemonchus contortus in brazil, this strain of the parasite was submitted to a controlled anthelmintic test. eighty worm-free lambs were randomly split into two groups of 40. each lamb in the first group was infected with 5000 third stage larvae (l3) of the ivermectin-resistant strain; the remaining 40 lambs were each infected with 5000 l3 of a h. contortus strain of known susceptibility to the major groups of anthelmi ... | 1991 | 1957487 |
| effectiveness of strategic anthelmintic dosing in controlling haemonchus contortus infections in sheep in the united kingdom. | the strategic use of anthelmintics in the control of infections of haemonchus contortus in ewes and lambs, was investigated in a series of paddock trials. the levels of infection and clinical signs associated with the presence of either benzimidazole-resistant or benzimidazole-susceptible strains of h contortus in lambs were controlled by regular drenching with levamisole or mebendazole, respectively, or by the strategic use of closantel in combination with mebendazole. in the latter case, contr ... | 1991 | 1957469 |
| non-specific resistance of sheep against haemonchus contortus with freund's complete adjuvant. | six groups of four ovines each were injected intraperitoneally with freund's complete adjuvant (fca), at various times before, during, or after infection with 10 000 larvae (l3) of haemonchus contortus per sheep. animals in groups a and b received fca on days 14 and 7, respectively, before infection. ovines in group c were treated with fca on the same day of infection; while sheep in groups d, e, and f were injected with the adjuvant on days 7, 14, and 21, respectively, after infection. signific ... | 1991 | 1956702 |
| synthesis and biological activity of a series of diaryl-substituted alpha-cyano-beta-hydroxypropenamides, a new class of anthelmintic agents. | a series of alpha-cyano-beta-hydroxypropenamides was prepared and tested for anthelmintic activity. alpha-cyano-beta-hydroxy-n-[4- (trifluoromethyl)phenyl]-3-[4-(trifluoromethyl)phenyl]propenamide (1) showed good activity against the nematode nematospirodes dubius in a mixed parasite infection in mice; several of the analogues were also effective against the cestode hymenolepis nana. in sheep trials, 1 caused 100% reduction of the hematophagous nematode haemonchus contortus after a single dose o ... | 1991 | 1956049 |
| effectiveness of clean grazing strategies in controlling haemonchus contortus infections in sheep in the united kingdom. | the effectiveness of clean grazing systems for controlling the sheep abomasal parasite haemonchus contortus under experimental conditions was monitored for a grazing season in ewes and lambs carrying either benzimidazole-susceptible or resistant populations of the parasite. both preventive and evasive strategies failed to give effective control of h contortus. lambs grazing with ewes that had received no anthelmintic showed clinical signs of haemonchosis by early july. lambs from ewes dosed with ... | 1991 | 1949535 |
| protective immunity to a blood-feeding nematode (haemonchus contortus) induced by parasite gut antigens. | to determine the ability of gut antigens to induce a protective immune response against blood-feeding nematodes, isolated gut antigens were used to immunize goats against haemonchus contortus. immunization-induced antibody responses recognized parasite gut antigens which were associated predominantly with the microvillous membrane region of the parasite gut. antibody from immune serum also recognized seven predominant gut proteins on a western blot (immunoblot). several of these proteins appeare ... | 1991 | 1937800 |
| post natal ontogeny of immunological responsiveness in merino sheep. | sheep in five age groups (two weeks, 10 weeks, 18 weeks, six months and four years old) were immunised systemically, twice, with ovalbumin or brucella abortus (live or killed) and antibody responses in blood were measured. the animals were also infected with the nematode parasites trichostrongylus colubriformis and haemonchus contortus and faecal egg counts and serum antibody responses to larval antigens were measured. the experiments were designed so that, as far as possible, the effect of age ... | 1991 | 1910202 |
| periparturient rise in faecal nematode egg counts in west african dwarf sheep in southern ghana in the absence of arrested strongyle larvae. | the nematode egg output of two groups of ewes, a pregnant test group (2-3 years of age) mated between march and april and a non-pregnant control group (5-6 years of age) was followed. the worm burdens acquired by worm-free 'tracer' lambs were also followed on the same pasture from march 1988 to february 1989. there was a significant difference (p less than 0.05) in the magnitude of the egg output in the test group compared with the control group. in the test ewes, an initial rise in egg producti ... | 1991 | 1897121 |
| fecundity of gastrointestinal trichostrongylid nematodes of sheep in the field. | twenty-two dorset rambouillet lambs were moved to contaminated pasture on apr 1, 1987. at regular intervals thereafter, pairs of lambs were withdrawn and euthanatized. gastrointestinal parasites in the abomasum, small intestine, cecum, and large intestine were removed and counted. the last pair of lambs was euthanatized 8 months after original placement on the contaminated pasture. fecal samples were taken at 3- to 4-week intervals throughout the grazing season and the fecal egg counts were used ... | 1991 | 1892277 |
| interaction of benzimidazole anthelmintics with haemonchus contortus tubulin: binding affinity and anthelmintic efficacy. | the ability of various benzimidazoles (bzs) to bind tubulin under different conditions was assessed by determining their ic50 values (the concentration of unlabeled drug required to inhibit 50% of the labeled drug binding), ka (the apparent equilibrium association constant) and bmax (the maximum binding at infinite [bz] = [drug-receptor]). the ability of unlabeled benzimidazoles--fenbendazole, mebendazole (mbz), oxibendazole (obz), albendazole (abz), rycobendazole (albendazole sulfoxide, abzso), ... | 1991 | 1889474 |
| concurrent infections with the ruminant nematodes haemonchus contortus and trichostrongylus colubriformis in jirds, meriones unguiculatus, and use of this model for anthelmintic studies. | haemonchus contortus- and trichostrongylus colubriformis-infected jirds (meriones unguiculatus) are useful for anthelmintic studies. with concurrent infections of these parasites established in the jird, questions of not only anthelmintic activity, but to some extent spectrum, could be assessed in a single model system. this report outlines a model using immunosuppressed (0.02% hydrocortisone in feed) jirds concurrently infected with h. contortus and t. colubriformis. immunosuppressed jirds were ... | 1991 | 1865271 |
| changes in liveweight gain and blood constituents in experimental infection of goats with a goat-derived compared with a sheep-derived strain of haemonchus contortus. | two groups of goats were experimentally infected with two different strains of haemonchus contortus and compared with the controls. group a animals were infected with a goat-derived strain (gds) while group b animals were infected with a sheep-derived strain (sds). changes in the liveweights and some blood constitutents between the two infected groups were compared. the pathogenic effects of the gds larvae were generally more serious when compared with those of the sds larvae. | 1991 | 1858284 |
| serum igg response of manchego lambs to infections with haemonchus contortus and preliminary characterization of adult antigens. | manchego lambs (16-18 weeks old) were infected with 2500 infective larvae (l3) of haemonchus contortus and challenged 2 months later with 5000 l3. the serum igg anti-haemonchus response was estimated by enzyme-linked immunosorbent assay (elisa) using soluble proteins from adults and l3. previously infected manchego lambs failed to mount a protective immune response against challenge, at least as assessed by faecal egg counts and pre-patency periods. primary infection did not provoke any rise in ... | 1991 | 1858283 |
| beta-tubulin and benzimidazole resistance in the sheep nematode haemonchus contortus. | we have compared benzimidazole (bz) susceptible (s) and resistant (r) strains of haemonchus contortus from sheep by two-dimensional polyacrylamide gel electrophoresis (2-d page), western blotting and elisa techniques. the s strain bound more drug per mg protein than the r strain. bz binding could be resolved into high-affinity and low-affinity binding. low-affinity binding in parasite preparations devoid of tubulin was observed, but high-affinity binding occurred only in preparations containing ... | 1991 | 1857382 |
| protective studies in sheep immunized with cuticular collagen proteins and peptides of haemonchus contortus. | twenty-eight nonsibling sheep aged approximately 12 months and raised in a helminth-free environment were used in two protection studies. immunizations were conducted by two intramuscular injections 30 days apart with a synthetic 18aa cuticle collagen peptide and native cuticle collagens derived from the third- and fourth-stage larvae of haemonchus contortus. ten days following the last immunization, the sheep were each given 500 infective h. contortus larvae per day for five consecutive days by ... | 1991 | 1852473 |
| cloning of a cdna encoding phosphofructokinase from haemonchus contortus. | phosphofructokinase (pfk), the key regulatory enzyme in glycolysis, has been cloned from the pathogenic parasitic nematode haemonchus contortus by functional complementation in escherichia coli. an e. coli strain deleted for both pfk loci (strain df1020) was transformed with plasmid dna from a lambda zap ii h. contortus cdna library. two out of 3 x 10(7) transformants were able to grow on minimal medium with mannitol as the sole carbon source. a plasmid, ppfk, containing a 2.7-kb insert, was iso ... | 1991 | 1838137 |
| [development and survival of haemonchus contortus isolated from sheep on a pasture at bunia (itiri, zaire)]. | development and survival of haemonchus contortus larvae were studied from december 1987 to november 1988 during three different periods (dry season, first and second rainy seasons) on an experimentally infected pasture at bunia (ituri, zaïre). whatever the season, eggs developed into infective larvae within six days and the largest number of larvae on the herbage occurred between the 12th and the 18th day post deposition. however, the two rainy seasons were the most favourable for transmission b ... | 1991 | 1818364 |
| blood gastrin and pepsinogen responses of native village goats in malaysia to infection with haemonchus contortus. | blood gastrin and pepsinogen responses of native village goats in malaysia to a single dose of 10,500 infective haemonchus contortus larvae were investigated. both blood values were significantly elevated within a week of infection and exhibited a highly significant correlation during the study. the magnitude of the blood gastrin response was, however, significantly greater than that of pepsinogen during the period that both blood values were elevated. it is suggested that blood gastrin assay ma ... | 1991 | 1796870 |
| production and characterization of monoclonal antibodies against excretory-secretory products of fasciola hepatica. | four monoclonal antibodies (mabs) (9.49, 24.27, 46.71 and 179.57) were produced against fasciola hepatica excretory-secretory products. isotype analysis revealed the antibodies to be igm, igg3, igg1, and igm. in immunoblot assays, the mabs recognized different antigenic polypeptides migrating between 29 and 180 kda. specificity of the mabs was evaluated by elisa against antigens of fascioloides magna, anoplocephala magna, stichorchis subtriquetrus, haemonchus contortus, sheep liver extract (sle) ... | 1991 | 1788930 |
| effect of weaning on antibody responses and nematode parasitism in merino lambs. | lambs weaned at eight weeks old were compared with control lambs which remained with their dams; both groups grazed the same pasture. weaning significantly reduced the growth rate, control lambs being, on average, 6 kg heavier than weaned lambs at 15 weeks old. when contamination of pasture with larval parasites was light, both groups of lambs suffered only modest parasitic infections. when lambs were experimentally infected with 5000 haemonchus contortus and 10,000 trichostrongylus colubriformi ... | 1991 | 1788476 |
| disposition of oxfendazole in goats and efficacy compared with sheep. | the disposition of intraruminally administered oxfendazole (ofz) in goats was studied at 5, 10 and 20 mg kg-1. the area under the plasma concentration with time curve (auc) increased with increasing dose but at a declining rate. auc was lower after intra-abomasal compared with intraruminal administration. ofz was less effective against drug resistant trichostrongylus colubriformis in goats than in sheep but was of similar efficacy against drug resistant haemonchus contortus in both host species. ... | 1991 | 1780578 |
| ultrastructural changes associated with exsheathment of infective juveniles of haemonchus contortus. | ultrastructural changes associated with exsheathment of the infective juveniles of haemonchus contortus are described. hyaline ring formation occurs associated with annulations 10 and 20 and consists of the dissolution of the basal zone and the inner electron-dense layer resulting in the rupture of the sheath. these changes are consistent with the action of a protease-exsheathing enzyme. there is a significant reduction associated with exsheathment in the size of the excretory cells and the numb ... | 1991 | 1780179 |
| infection of goats with haemonchus contortus and trichostrongylus colubriformis: histopathology and ph changes. | two groups of goats were experimentally infected with haemonchus contortus and trichostrongylus colubriformis, and killed at various days after infection (dai). the percentage of worms that established in the abomasum and the small intestine was low. at necropsy, abomasums from infected goats had thickened walls and oedematous folds. at 7 dai there was an initial infiltration of eosinophils and some neutrophils which tend to increase with age of infection. the mean ph of the abomasum in goats in ... | 1991 | 1777801 |
| a study of the mortality and fecundity of haemonchus contortus in sheep following experimental infections. | the regulation of the fecundity and mortality of h. contortus in sheep was examined using a series of mathematical models. six-month-old dorset crossbred lambs were infected once only with various doses of infective h. contortus larvae (500-20,000 larvae). parasite mortality was found to be an increasing linear function of the magnitude of the initial infection over the range of doses examined. parasite fecundity was found to remain constant over the intensity and duration of the infection. the ... | 1991 | 1774120 |
| purified glutathione s-transferases from parasites as candidate protective antigens. | glutathione s-transferase (gst) activity was detected in larvae of the australian sheep blowfly lucilia cuprina, and in the nematode haemonchus contortus. a specific inhibitor of the enzyme was shown to affect survival of both species of parasite in vitro. gst from both parasites has been purified and partially characterized. antisera raised to the purified enzymes were shown to inhibit the enzyme activity in vitro. however, the antisera had no effect on the survival of either parasite. | 1991 | 1774119 |
| detection of resistance to ivermectin in haemonchus contortus. | infective, third-stage (l3) larvae of haemonchus contortus isolates resistant to ivermectin (ivm) show a decreased sensitivity to ivm-induced paralysis in vitro. the inhibition of larval motility by ivm can be detected in l3 larvae incubated in the dark on an agar matrix containing ivm, by the failure of affected larvae to move when stimulated by exposure to light. optimally, avermectin (avm) potency is quantified after three cycles, each involving storage in the dark for 24 h followed by a brie ... | 1991 | 1774112 |
| [the threat of wide dissemination of anthelmintic resistance by veld ram performance testing units]. | a veld ram performance testing unit consists of an association of stud or commercial ram breeders, who compare the performance of selected rams under field conditions on common pastures. the best performers are subsequently auctioned at public sales. to date, at least 10 merino veld ram clubs have been established in various centres in south africa. a strain of haemonchus contortus, which was isolated from the pastures of one of these performance testing units, was found to be resistant to iverm ... | 1991 | 1770493 |
| interaction of parasitism and nutrition and their effects on production and clinical parameters in goats. | weaned wether goats (n = 144) approximately 6 months of age were placed in a 2 x 3 factorial design experiment for 5 months to test the main effects and interaction of two levels of nutrition (growth + maintenance, nut1; twice growth + maintenance, nut2) and three levels of haemonchus contortus burden (0, 500 and 2000 larvae administered every 2 weeks: w0, w500 w2000, respectively) on weight, feed intake, level of infection and packed cell volume (pcv). the rationale for the experimental design ... | 1991 | 1763494 |
| effects of time of day, season and stratum on haemonchus contortus and haemonchus placei third-stage larvae on irrigated pasture. | the effect of time of day, season and stratum of herbage and soil on the availability of haemonchus contortus and haemonchus placei third-stage larvae (l3) on pasture was assessed. feces from infected calves and lambs were placed on pasture plots and samples of upper herbage, lower herbage, mat and soil were collected at five intervals per day throughout the daylight hours on 18 sample days over 12 months. using recovery rate factors derived from a preliminary investigation on the efficacy of la ... | 1991 | 1763493 |
| effects of cholinergic drugs on longitudinal contraction in levamisole-susceptible and -resistant haemonchus contortus. | a novel force transducer was used to measure the effects of cholinergic agonists on longitudinal contraction in haemonchus contortus. drugs were applied to whole worms or injected via a cannula in the pseudocoelomic cavity. a number of agonists, including nicotine and the anthelmintics m-aminolevamisole, levamisole and morantel, caused contractions in whole worms. four- to 25-fold increases in concentration of the active compounds were required to cause contractions in each of two levamisole-res ... | 1991 | 1757196 |
| immunity to haemonchus contortus and the cellular response to helminth antigens in the mammary gland of non-lactating sheep. | cellular exudates induced by infusion with helminth antigens were examined in non-lactating mammary glands of ewes immune to infection with the abomasal nematode, haemonchus contortus. secondary immunological responsiveness was expressed in two ways. firstly, antigens from adult h. contortus elicited larger eosinophil-rich cellular exudates in immune compared to non-immune ewes. in this situation, secondary responsiveness in the mammary gland must have been generated through abomasal infection w ... | 1991 | 1757191 |
| local eradication of haemonchus contortus using closantel. | 1991 | 1755790 | |
| a possible role of caesium radiations in the control of propagation of hookworm. | faeces charcoal mixtures containing eggs of sheep hookworm, haemonchus contortus were exposed to caesium radiations (23 r to 1656 r) from 1st to 7th day of incubation. each plate was exposed only once. a dose related inhibition of transformation of eggs to infective larvae was observed. the maximum effect was observed on 2nd day of incubation. the radiation has maximum effect on the 1st stage larvae followed by 2nd stage. the 3rd stage or ineffective larvae are relatively resistant to the effect ... | 1991 | 1743750 |
| three beta-tubulin cdnas from the parasitic nematode haemonchus contortus. | experimental evidence indicates that tubulin is the site of action of the anthelmintic benzimidazoles. furthermore, certain residues of beta-tubulin seem to be critical for this mechanism. although the benzimidazoles selectively affect nematode vs. mammalian beta-tubulin, the molecular basis for this differential action is not known. to enhance our understanding of this phenomenon, and to provide the basis for investigating benzimidazole resistance in parasitic nematodes, we undertook the clonin ... | 1992 | 1741017 |
| cloning of a cdna encoding phosphoenolpyruvate carboxykinase from haemonchus contortus. | biochemical and metabolic data have led to the conclusion that the enzyme phosphoenolpyruvate carboxykinase (pepck; ec 4.1.1.32) contributes to a critical point of divergence in energy conservation pathways between mammals and nematodes. to facilitate the determination of the molecular basis for host vs parasite differences in pepck, we have cloned a cdna encoding this enzyme from a parasitic nematode of ruminants, haemonchus contortus. h. contortus pepck was cloned by functional complementation ... | 1992 | 1741016 |
| identification of a novel brugia pahangi beta-tubulin gene (beta 2) and a 22-nucleotide spliced leader sequence on beta 1-tubulin mrna. | we have examined the expression of beta-tubulin genes in the parasitic nematode, brugia pahangi. a genomic library was constructed and screened by hybridization with a haemonchus contortus beta-tubulin cdna fragment which recognizes several b. pahangi beta-tubulin sequences, including sequences which correspond to the previously characterized beta 1-tubulin gene. the b. pahangi beta 2-tubulin gene was isolated by selecting clones which hybridize to the h. contortus beta-tubulin gene but which do ... | 1992 | 1741015 |
| biochemical characterisation of the enzyme responsible for "activated l-serine sulphydrase" activity in nematodes. | the biochemical properties of the enzyme responsible for nematode "activated l-serine sulphydrase" activity (l-cysteine + r-sh----cysteine thioether + h2s) have been investigated using primarily the gastro-intestinal nematodes nippostrongylus brasiliensis and haemonchus contortus. the activated l-serine sulphydrase enzyme was found to be cytosolic in origin and exhibited maximal activity at ph 9.0. enzyme activity was widely distributed amongst the major tissues of adult female ascaris suum but ... | 1992 | 1740180 |
| vital staining of glycoprotein secreted by infective third stage larvae of haemonchus contortus prior to exsheathment. | staining of infective third stage larvae of haemonchus contortus prior to exsheathment shows that protein is exuded from the head region and spreads between the cuticles and that a carbohydrate-containing substance is also found between the l2 and l3 cuticles throughout, at exactly the same sites in this nematode. this glycoprotein, which is either secreted from the mouth or the amphids or both is exuded whether or not the larvae have been stimulated to exsheath. slight staining was also sometim ... | 1990 | 1699905 |