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Biomedical subjects

C Dobson

Publications and source records attributed to C Dobson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Excretory-secretory antigens from adult Nematospiroides dubius.

Adult Nematospiroides dubius excretory-secretory (ES) products were collected from worms cultured in vitro, radiolabelled and separated by sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE). The components were characterized and assessed for molecular weight (MW) after autoradiography and gel staining, for antigenicity in immunoblots, for sensitivity to protease enzymes, and for carbohydrate content. ES contained at least 18 denatured components from MW less than 20,000 to greater than 200,000. At least one of the surface proteins of adults was found with the ES antigens recovered when adults were cultured in vitro. Molecules with MW 200,000, 78,000 and 60,000 were glycoproteins and reacted with immune mouse serum in Western blots. The dominant ES, MW 60,000 component stained with periodic acid-Schiff (PAS), bound lectins with affinity for D-mannose, and was resistant to peptic and tryptic but not V8 protease digestion.

Animals↗
PubMed1989

Hereford cattle protected against Boophilus microplus with antigens purified by immunoaffinity chromatography from larval and adult ticks.

Tick larvae (Boophilus microplus) were extracted, fractionated by gel filtration and ion-exchange chromatography, and the fractions assayed by enzyme-linked immunosorbent assay (ELISA) against sera from cattle immunized and protected by antigens from the mid-gut of adult ticks. Unfractionated, whole larval extracts and selected reactive components were used to vaccinate cattle; they decreased the number of ticks dropped after challenge, but the effect of treatment was not significant. Antigens purified from crude larval extracts by affinity chromatography, using immunoglobulin ligands from an immune steer vaccinated with tick mid-gut antigens, also failed to protect cattle. However, tick extracts from both larval and adult ticks, which were first separated into membrane-associated and soluble fractions and then purified by exposure to the affinity ligands, protected cattle greater than 80% against subsequent challenge with ticks.

Animals↗
PubMed1988

Hereford cattle immunized and protected against Boophilus microplus with soluble and membrane-associated antigens from the midgut of ticks.

Hereford cattle were immunized with membranes and soluble components extracted from the midgut of Boophilus microplus. Membrane vaccines protected cattle (91%) against challenge with 3 x 20,000 larval ticks administered at intervals of 7 days. Vaccines made from soluble antigens did not protect cattle. Antibody levels measured by enzyme-linked immunosorbent assay (ELISA) related to the levels of protection induced by vaccination.

Animals↗
PubMed1988

Vaccines to protect Hereford cattle against the cattle tick, Boophilus microplus.

Vaccines made from gut and gut and synganglion tissue dissected from Boophilus microplus gave 87% and 80% protection, respectively, compared with adjuvant-injected controls in cattle against three infestations with 20,000 larval ticks administered over 14 days. A vaccine prepared from synganglion alone did not protect cattle. Ticks collected from vaccinated cattle produced 95% and 91% fewer eggs, respectively, than ticks from control animals. Vaccinated cattle were protected (36%) 7 months after they had been immunized with tick antigens. Antibody responses to the vaccines were detected by enzyme-linked immunosorbent assay (ELISA).

Animals↗
PubMed1987

Mice vaccinated against Nematospiroides dubius with antigens isolated by affinity chromatography from adult worms.

A crude soluble extract (AWH) obtained from homogenized adult Nematospiroides dubius worms was fractionated into normal (NMIgAg) and immune (IMIgAg) antigens by sequential passage through Sepharose 4B, and CNBr-activated Sepharose 4B to which immunoglobulins from normal (NMIg) and N. dubius-infected mouse serum (IMIg) had been coupled. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions showed that MNIgAg and IMIgAg contained several proteins with molecular weights (MW) between 20,000 and 200,000. IMIgAg contained 2 polypeptides, MW 24,000 and 55,000, which reacted strongly in western blot analysis against IMIg; the larger molecule related to a cuticular component of the worm. Protective high MW AWH G-200 filtrates shared 5 polypeptides with IMIgAg (MW 85,000-200,000) together with several smaller molecules (MW 30,000-less than 10,000). The MW 55,000 and 24,000 components concentrated in IMIgAg were restricted to non-protective low MW AWH gel filtrates. BCF1 mice vaccinated with IMIgAg were protected against N. dubius. Worm numbers, size and fecundity were reduced to an extent commensurate with that obtained in mice vaccinated with AWH. Mice vaccinated with NMIgAg showed partial resistance. The role of surface and dominant parasite immunogens in immunity is discussed.

Animals↗
PubMed1987

Surface and excretory/secretory antigens of Nematospiroides dubius.

Sera from mice immunized by repeated anthelmintic-terminated infections (IMS) or by a single primary infection (PMS) of Nematospiroides dubius were assayed for antibodies reactive with N. dubius antigens. The surface proteins of adult worms, the excretory/secretory (ES) proteins of adult worms and soluble extracts from lysates of both adult (AWH) and larval (LWH) N. dubius were used in an immunoprecipitation assay. A 60,000 MW protein was the major radiolabelled surface and ES protein. This antigen was dominant in precipitates by IMS from AWH, ES and surface-labelled worms but was not precipitated by PMS from any antigen source. Minor antigens of 20,000, 33,000, 36,000, 45,000, 50,000 and 66,000 MW were precipitated from AWH by both PMS and IMS but not from ES or surface-labelled worms. The dominant antigen precipitated from LWH by IMS was 20,000 MW. This antigen was not precipitated by PMS but larval antigens of 65,000 and 96,000 MW were precipitated by both PMS and IMS. The major antigens precipitated by IMS were adult (60,000 MW) and larvae (20,000 MW) stage-specific but some minor antigens (33,000, 45,000, 50,000 MW) were common to both stages. Our results show that the dominant antigen precipitated by serum immunoglobulin from mice immunized by repeated anthelmintic-terminated infections are proteins present on both the cuticle surface and in the ES.

Animals↗
PubMed1987

Stage-specific antigens of Nematospiroides dubius Baylis, 1926 (Nematoda: Heligmosomides).

Antigens were identified from Nematospiroides dubius recovered from outbred Quackenbush mice between 4 and 10 days postinoculation (PI). Parasite surface proteins were radioiodinated and extracts of the whole worms were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose, and reacted with normal and immune mouse sera followed by an avidin-biotin-peroxidase assay. Antigens ranged between 250,000 and 20,000 molecular weight (MW). A major surface antigen, 60,000 MW, which appeared to be a complex of different antigens, and a 250,000-MW internal antigen were found on fourth-stage (L4) and fifth-stage (L5) larvae 5-10 days PI but not earlier. A group of minor surface antigens (24,000-30,000 MW) were also expressed as larvae molted from L4 to L5, 6 and 7 days PI, but they differed from antigens of similar MW expressed by adult worms. An antigen, 45,000 MW, was detected in worms 5-10 days PI, but it was only expressed on the surface of L5 worms 9 and 10 days PI. We suggest that the antigen(s) common to adults and larvae may account for protective immunity.

Animals↗
PubMed1986

Nematospiroides dubius: direct and correlated responses to selection for high and low immune responsiveness in mice.

High and low immune responder lines of mice were bred selectively from an allogeneic stock over 10 generations, based on their fecal parasite egg count assayed 3 weeks after reinfection with 100 Nematospiroides dubius larvae. By generation 10, (F10), the low immune response mice voided about 10 times as many fecal N. dubius eggs as the high immune response mice. Realized heritability for the selected trait, fecal egg count after secondary infection (= protective immunity), was 0.35 at F7. F7 was considered the selection limit. Selection for change in fecal egg count did not significantly influence the conformational nor reproductive characteristics of these mice. Significant phenotypic and genetic correlations were evident between the selected character and innate immunity to N. dubius, humoral antibody response to N. dubius infection, and establishment, growth, and reproduction of N. dubius in the selected mice.

Animals↗
PubMed1986

Immunodiagnosis of Entamoeba histolytica and Ascaris lumbricoides infections in Caucasian and aboriginal Australians.

The immunodiagnostic efficiency of an indirect immunofluorescence test (IFAT) and in vitro lymphocyte proliferative responsiveness (cell mediated immunity test, CMIT) used to measure the immunological responses of individuals with known natural Entamoeba histolytica and Ascaris lumbricoides infections, was studied under survey conditions. E. histolytica was common among Aborigines from Cherbourg, Kowanyama and Central Australia, but it was not found in Brisbane Caucasians. The protozoan was selected for the study because it was prevalent and purified antigen was commercially available. Immunodiagnosis for A. lumbricoides was made using an antigen prepared by affinity chromatography. Diagnosis based on frequency distribution of immunological data gave valid assessment of the number of infected individuals in each population studied.

Adolescent↗
PubMed1986

Inheritance of immunity in mice to challenge infection with Nematospiroides dubius.

Two lines of mice (Mus musculus) were selectively reared over 10 generations for high (H) and low (L) levels of immune response to Nematospiroides dubius, an enteric nematode parasite. Filial and backcross families were derived from the two parent lines. The mode of inheritance of the trait, immune response to challenge infection with N. dubius, was analysed by comparing the levels of infection in the parental, filial and backcross (BC) families of mice. The immunity of the F1 mice was found to be dissimilar to both parents, but was closer to the H value than to the level of immunity in the L mice. The backcross to H progeny showed levels of immunity approaching that of the H mice, whereas only two of four backcross to L families were low immune responders. Analysis of these results indicated that the inheritance of immunity in these mice to challenge infection with N. dubius was quantitative, partially dominant for high immune response, and additive, in nature.

Animals↗
PubMed1986

Protective antigens in fractions of adult Nematospiroides dubius.

Adult Nematospiroides dubius crude soluble homogenate consistently produced five fractions (F1-5) after filtration through Sephadex G-200 with molecular weights of greater than 300,000, 240,000, 83,000, 31,000 and less than 10,000. The high molecular weight F1 and F2 reacted strongly with serum from previously infected mice in ELISA. Protective immunity was associated with F1 N. dubius immunogens (molecular weight greater than 300,000). Immunization with smaller molecular weight fractions also reduced worm recoveries following challenge infections but to a lesser extent.

Animals↗
PubMed1986

Nematospiroides dubius: multiple infections in mice bred for immune responsiveness.

Allogeneic mice were reared over 5 generations in a 2-way selection for high (H) and low (L) immune responsiveness to the intestinal trichostrongylid nematode Nematospiroides dubius. After 5 generations of selective breeding, the H mice passed fewer N. dubius eggs and harbored fewer, smaller and less fecund worms than did the L mice. These trends were observed after each of 4 consecutive infections, which were all treated with levamisole before reinfection. Further, more H than L mice were worm-free, and H mice were sensitized to sterile immunity by fewer infections than were needed by the L mice. These results encourage the view that the selective breeding of host species of agricultural importance is a valuable means of biologic control of nematodiasis.

Animals↗
PubMed1985

Mathematical models of patterns of seizures. Their use in the evaluation of drugs.

The analysis of the results of many well-designed, double-blind trials of anticonvulsant drugs has been unsophisticated. We draw attention to the nonrandom occurrence of seizures, which negates the simple comparison of average seizure frequency. We propose a method of taking into account clustering of seizures when deciding on the appropriate length of follow-up after introducing a new treatment. Deterministic and nondeterministic models were used to show why there may be reasons for sometimes using more than one drug in the treatment of epilepsy.

Anticonvulsants↗
PubMed1985

Vaccination against Nematospiroides dubius in mice using adult worm extracts as antigens.

Various preparations of somatic Nematospiroides dubius antigens were emulsified in Freund's complete adjuvant and assayed in Quackenbush mice for efficacy as vaccines against homologous infection. Soluble and particulate fractions were given by two different routes. Only minimal protection was induced by vaccination with either soluble or particulate parasite fractions used independently when compared with the adjuvant control. Fewer and smaller worms were recovered from, and significantly fewer parasite eggs were voided by, mice which had been treated previously with both soluble somatic protein (15 micrograms N. dubius per mouse) by the intraperitoneal route and particulate antigen by subcutaneous injection. These mice showed higher antibody titres in comparison with other mice treated with either fraction alone. Further, treatment with both antigen fractions together appeared to exert a synergistic effect in comparison with either fraction administered alone.

Animals↗