Biomedical subjects

C Boulard

Publications and source records attributed to C Boulard.

At least 55 records · Page 3Linked to original sources

PubMed1993

In vitro and ex vivo responses of bovine lymphocytes to hypodermin C, an enzyme secreted by Hypoderma lineatum (insect oestridae).

The aim of this work was to determine if Hypodermin C (HC), an enzyme secreted by Hypoderma spp. larvae during their migration, is able to depress the lymphocyte response to mitogens and antigens. HC, when added to the lymphocyte culture, was able to influence the response of naive-calf lymphocytes to phytohemagglutinin. Secondly, injections of HC to uninfested and previously-infested cattle did not modify the proliferative response of the lymphocytes of these animals to mitogens. Thirdly, injections of HC to infested cattle did not negatively influence the specific humoral and cellular responses.

Animals↗

PubMed1993

Kinetic responses of parasite-specific antibody isotypes, blood leucocyte pattern and lymphocyte subsets in rats during primary infestation with Fasciola hepatica.

Antibody responses, blood leucocyte and splenic lymphocyte subset patterns were studied during a primary infection with Fasciola hepatica in the rat. The infection induced parasite-specific IgM by 2 weeks after infection. High levels of IgM antibodies were maintained for many weeks. The IgE response was biphasic with peaks at 5 and 9 weeks after infection which were correlated with different phases in the development of F. hepatica in the rat. Both IgG2a and IgG1 antibodies were detected but the titre of IgG2a augmented slightly and rose more slowly than did that of IgG1. There was a rise in neutrophil and eosinophil numbers. Neutrophils did not increase before the fourth week but eosinophil numbers were raised by the second week after infection and remained high during the whole migratory phase of the parasite. In the spleen, the percentage of B lymphocytes increased and there was a decrease in the percentages of CD4+ and CD(8+)-like T lymphocytes. These results suggested that, in the rat infested with F. hepatica, TH2-like lymphocytes could be preferentially stimulated, as has been reported in murine schistosomiasis.

Analysis of Variance↗

PubMed1993

Efficacy of doramectin against warble fly larvae (Hypoderma bovis).

The efficacy of doramectin in the treatment of cattle harbouring naturally acquired infestations of first, second and third instar larvae of Hypoderma bovis was determined in two studies carried out in the Burgundy region of France. In the first study, cattle on six farms with a history of H. bovis infestations were treated during October 1989 with either doramectin at a dose of 200 micrograms kg-1 liveweight (186 animals) or with an equivalent volume of saline (157 animals). During the following March and April, all animals were examined for the presence of warbles. In the second study, cattle on four farms with warbles present in their backs were treated during March 1990, with either doramectin or saline (as before). The viability of larvae within each warble on all the animals was then assessed every 2 days for 14 days. In Study 1, no warbles were present in any of the doramectin-treated cattle at any time, whereas warbles were found in 135 saline-treated animals. In Study 2, all larvae in warbles on the backs of the doramectin-treated cattle were dead by Day 14 after treatment, whereas viable larvae were still present in warbles in the backs of all saline-treated cattle. No adverse reaction to doramectin treatment was observed in any animal at any time. It was concluded that doramectin is both safe and 100% efficacious in the treatment of first, second and third instar H. bovis infections of cattle.

Analysis of Variance↗

PubMed1992

Effect of hypodermin A, an enzyme secreted by Hypoderma lineatum (Insect Oestridae), on the bovine immune system.

The absence of any inflammatory reaction around the first instar larvae (L1) of Hypoderma sp. in previously uninfested cattle suggested that these larvae may escape the non-specific defence system of the host. Immunosuppression had been noted during an experimental infestation. The aim of this work was to determine more precisely the potential role of hypodermin A (HA), an enzyme secreted by the larvae, in this immunosuppression. HA was found to have no effect on unstimulated lymphocytes from naive cattle but could influence the response of these cells to mitogens. In calves, injection of HA was accompanied by a decrease in the lymphocyte proliferative response to mitogens. This immunodepression lasted only for the duration of enzyme injections. In cattle, when HA is added, the antigen-dependent proliferative response increased significantly after 1 week of injection and disappeared 2 weeks after the end of the injection period. Finally, the rate of production of anti-HA antibodies increased at the same rate for calves and cows, and achieved a similar level. These results suggest that HA significantly modified the lymphoproliferative response for naive cattle and, to a lesser extent, immune cattle during the time of administration only.

Animals↗

PubMed1992

Effect of genetic type, lactation and management on helminth infection of ewes in an intensive grazing system on irrigated pasture.

A survey of helminth infection was conducted in a flock of 290 ewes distributed into Romanov (R), Merinos d'Arles (M) and Romanov x Merinos (R x M) genetic types, grazing irrigated pasture in the south of France. Faecal egg and larval counts were done seven times per year from 1981 to 1984 on homogeneous groups of ewes and then individually once to four times every autumn from 1985 to 1988. Helminth fauna was diverse and more abundant during autumn. High levels of strongyle infection occurred in the ewes that remained on the same irrigated pastures during summer. Moving to Alpian pastures during the summer lowered autumnal infection. Significant differences between genotypes in intensity of infection were observed in the order R > R x M > M for strongyles (Teladorsagia circumcincta and/or Trichostrongylus vitrinus, Chabertia ovina and/or Oesophagostomum venulosum, Nematodirus spp.), Moniezia spp. and Dictyocaulus filaria. The hierarchy was reversed for Fasciola hepatica infection and not consistent from one year to another for protostrongylid infections. The effect of lactation intensity on the postparturient rise was studied by equilibrating number of ewes according to reproductive status (zero, one or two lambs in lactation). Merino ewes with two lambs in lactation, as well as primiparous Romanov ewes, had significantly higher strongyle infections than the others. The repeatabilities of the larval and egg counts between the four trial years were 0.24, 0.23 and 0.16, respectively, for protostrongyles, Nematodirus and strongyles, with higher intra-annual values for protostrongyles and inconsistently significant results for strongyles due to the presence of several species.

Animals↗

PubMed1992

Humoral and cellular immune responses in rats during a primary infestation with Fasciola hepatica.

The antibody and lymphocyte responses to Fasciola hepatica were studied in rats. Infested rats were shown to produce antibodies against excretory-secretory (ES) products of adult flukes as early as the first week after infestation. Immunoblotting revealed fractions of ES products of adult flukes to which antibodies were progressively produced during the course of the infestation. Proliferation of peripheral blood lymphocytes, splenocytes and thymocytes when incubated with different mitogens (Concanavalin A (ConA) or Pokeweed mitogen (PWM) or different liver fluke antigens (metacercariae antigen (EM) or ES products of adult flukes) have been studied. In response to these mitogens or antigens, splenocytes were stimulated on the second and fourth weeks after infestation. Thymocytes were significantly activated by PWM on the second week but peripheral blood lymphocytes did not show any statistically significant response. Results obtained in antibody production, immunoblotting and lymphocyte proliferation suggested sequential releases of F. hepatica substances and the existence of common proteins between adult and juvenile parasite stages. Cellular and humoral responses observed in this work did not seem to confer a complete resistance to liver fluke primary infestation on the rat.

Animals↗

PubMed1992

Opsonization of Streptococcus agalactiae of bovine origin by complement and antibodies against group B polysaccharide.

The contribution of bovine complement and antibodies (Ab) against the group B polysaccharidic antigen (GBA) to the opsonization of Streptococcus agalactiae isolated from bovine mastitis cases was investigated by using affinity-purified Ab. GBA-specific Ab were not opsonic by themselves, but in the presence of complement (precolostral calf serum) with an opsonization time of 15 min, they exhibited a dose-dependent opsonic activity in a polymorphonuclear leukocyte chemiluminescence assay. Kinetic studies of the deposition of complement component C3 on protein X-bearing nontypeable (NT/X) strains with an enzyme-linked immunosorbent assay showed that C3 was deposited on bacteria in the absence of Ab but that GBA-specific Ab markedly accelerated the process by reducing the lag phase, which extended up to 15 min when Ab were absent. In the absence of Ab, C3 deposition was inhibited by 5 mM salicylaldoxime or heat treatment at 56 degrees C for 3 min and necessitated Mg2+ ions but not Ca2+ ions, suggesting that activation of complement was effected by the alternative pathway only. When GBA-specific Ab were added to complement, the inhibitory treatments lost much of their efficacy, suggesting that the classical pathway was recruited. Deposition of C3 on NT/X strains in the absence of Ab induced chemiluminescence and phagocytic killing. With the addition of GBA-specific Ab, the numbers of surviving bacteria were halved (P < 0.05) compared with killing in the presence of complement alone. It can be concluded that NT/X strains are activators of the alternative pathway of complement and that GBA-specific Ab reinforce the opsonic efficiency of serum by recruiting the classical pathway and slightly enhancing phagocytic killing.

Animals↗

PubMed1991

The response of cattle vaccinated with hypodermin A to a natural infestation of Hypoderma bovis and Hypoderma lineatum.

In this study, we have determined whether immunization with hypodermin A (HA), associated with various adjuvants, could provide protective immunity for calves when challenged with a natural hypoderma infestation. Groups of naive calves were vaccinated with HA antigen alone or with adjuvants [Freund's incomplete adjuvant (FIA) or alumina phosphate (AP)]. Subcutaneous injection with HA antigen with or without adjuvant did not significantly protect calves against a natural hypodermosis infestation. The humoral response during the infestation period was evaluated by ELISA. A significant earlier and greater response was induced in groups vaccinated with HA alone and HA combined with FIA. These results indicate that HA, in this vaccination protocol, induces a very incomplete protection in calves exposed to a natural infestation.

Adjuvants, Immunologic↗

PubMed1991

Use of pooled serum or milk samples for the epidemiological surveillance of bovine hypodermosis.

An enzyme-linked immunosorbent assay (ELISA) was used on pooled serum and milk samples to determine whether hypodermosis could be detected where a larger sero-epidemiological survey was required. This study was undertaken to assess the potential of this assay for testing sera on milk samples, pooled from 10 cows, and determining the period of the year when detection was optimal. The sensitivity of the assay was determined by increasingly diluting a positive serum with pooled negative sera, from 1:10 to 1:100. The diagnostic lower limit of the assay requires at least two serological reactors within a herd of 100. The kinetic development and depletion of anti-Hypoderma antibody of individual and pooled sera or milk from 30 cows was evaluated from November to July. Anti-Hypoderma antibody levels of two groups of 8 calves, one control and one teated with ivermectin (Ivomec), were tested from October to June. These preliminary results indicate that an ELISA assay on serum or milk samples pooled from 10 cows can be used between February and April to evaluate the prevalence of hypodermosis within cattle herds in France, demonstrating the feasibility of using pooled serum already collected for bovine leucosis testing.

Animals↗

PubMed1991

Cutaneous myiasis. Recent advances in biology, immunology and improvements of the control measures.

The evolution of the main topics of study related to the biology, the life-cycle and the distribution of insects causing cutaneous myiasis during the last century is presented. These subjects are still of interest and a synopsis of new data concerning Hypoderma tarandi, H. diana and Prezhevalskiana silenus is reported as well as the changes of distribution of some species such as Cochliomyia hominivorax. In the second part, an over view of what has been archived on myiasis immunology is reviewed. This is based on the work conducted on Lucilia cuprina and Hypoderma. The areas of research are serological diagnosis, disease monitoring, immunological mechanisms of host protection and parasite escape. The following topic reviewed the latest developments in chemotherapy, the problems associated with this approach to control the myiasis and the part played by these chemicals in successful eradication programs. In the last topic the latest results obtained with the use of biological measures to control C. hominivorax and H. bovis and H. lineatum are reported.

Animals↗

PubMed1990

Preliminary evaluation of four immunological tests for the early diagnosis of Hypoderma tarandi causing hypodermosis in reindeer.

294 serum samples from five Norwegian reindeer herds were examined for antibodies against Hypoderma tarandi L. The first and second larval instars of H. tarandi were tested as antigens in immunodiffusion tests, passive haemagglutination and an Enzyme-Linked Immunosorbent Assay (ELISA). The latter technique, using first instar antigens, produced the best results. A significant difference (P less than 0.1%) was observed between the antibody value of naive reindeer bred in France and those from infected Norwegian herds. No correlation was observed between the antibody titre and the number of warbles recovered at necropsy from the 294 Norwegian reindeer.

Animals↗

PubMed1990

Rabbit antibody responses to experimental infestation with Dermatobia hominis.

The three larval stages of Dermatobia hominis (Linnaeus) have been evaluated for their immunogenicity by ELISA and immunodiffusion (ID) using sera from experimentally infested rabbits. During a primary infestation, first instar D. hominis were found to cause most reaction and allowed the earliest diagnosis by ELISA. An inhibition of the antibody response against second and third instars was observed. The inhibition disappeared after departure of the larvae from the host. In experimentally immunized hosts the antibody response, following challenge, was highest against second and third instar antigens. Antibody remained elevated during the infestation but fell immediately after the larvae had left the host.

Animals↗

PubMed1989

Degradation of bovine C3 by serine proteases from parasites Hypoderma lineatum (Diptera, Oestridae).

Purified enzymes of Hypoderma lineatum (Insecta, Oestridae), were assayed for their proteolytic activity on bovine C3 in normal cattle sera. The products of cleavage by these serine proteases (hypodermins A, B, and C), were analysed by electrophoresis in SDS polyacrylamide gels followed by immunoblotting. The enzymatic attack was initially directed at the alpha polypeptide chain by hypodermin A at a concentration of 1 micrograms/ml of serum and by hypodermin B at 5 micrograms/ml. The generated peptides differed in their molecular size from those produced during natural degradation of C3 in a control serum by physiologically relevant enzymes. Hypodermin A, at a concentration of 1 microgram/ml, also caused a cleavage of the beta chain. At 5 micrograms/ml, hypodermin A induced total degradation of the C3 molecule. Hypodermin B (5 micrograms/ml) starts splitting C3 near cleavage sites of factor I. Bovine C3 appears to be highly sensitive to hypodermins A and B in normal sera. Apparent molecular sizes and alignment of the bovine C3 cleavage products are presented schematically. Hypodermin C, a collagenolytic enzyme, had no effect on C3 in normal sera. The biological consequences for the immunopathological reactions associated with hypodermosis are discussed.

Animals↗

PubMed1989

[Experimental equine fascioliasis: evolution of serologic, enzymatic and parasitic parameters].

Three, four, and one horses were respectively infected with 100, 1,000, and 5,000 metacercariae of Fasciola hepatica. Six of them were reinfected 38 weeks later with 1,000 metacercariae each. Specific antibodies assayed by counter-electrophoresis, passive hemagglutination and ELISA tests appeared three to six weeks post-infection and peaked 10 to 17 weeks post-infection. Horses infected by 1,000 metacercariae and more showed 17.6% of positive samples by counter-electrophoresis, 49.2% by ELISA, and 75.6% by passive hemagglutination. Plasma glutamate dehydrogenase and gamma-glutamyltransferase levels increased significantly 3 to 5 months post-infection in the most infected animals. Eggs of Fasciola hepatica were only observed in 2 of the 8 horses, 14 and 15 weeks post-infection. This last observation indicates the limits of fecal examination in the diagnosis of fascioliasis in horses.

Animals↗

PubMed1988

Incidence of a subclinical fascioliasis on antipyrine clearance and metabolite excretion in sheep.

1. The pharmacokinetics of i.v. antipyrine (25 mg/kg) used as a model compound, were determined in young male sheep, before and each month after an oral infestation by 150 metacercariae of Fasciola hepatica, and 8 weeks following a flukicidal treatment. 2. The parasitic pathology was ascertained by the clinical observation of animals and the increase in plasma antibodies directed against liver flukes. 3. A significant decrease in the total plasma clearance of the drug occurred by week 4 to 16, and a 1.7 fold increase in mean residence time occurred by week 12 post-infection. 4. Urinary excretion of antipyrine metabolites was determined before and 8 weeks following the infestation. 4-Hydroxyantipyrine was the major urinary metabolite and its excretion was decreased by 30% in infected sheep, whereas there was no change in the excretion of norantipyrine, 3-hydroxymethylantipyrine or unmetabolized drug. 5. It is concluded that the impairment of antipyrine clearance in the course of fascioliasis could be related to the decrease in liver microsomal cytochrome P-450-dependent mono-oxygenases observed in sheep with a similar parasitic burden.

Animals↗

PubMed1987

[Cimetidine treatment of primary hyperparathyroidism].

Since Sherwood's report in 1979, contradictory findings have been published with regarding the treatment of primary hyperparathyroidism with Cimetidine. We studied 16 patients with primary hyperparathyroidism treated with 1,200 mg of Cimetidine and followed-up clinically and biochemically. A decrease in serum calcium and urinary CAMP was observed after the fourth week of Cimetidine therapy with no significant change in parathormone levels. In none of the cases did Cimetidine seem to provide a treatment of hyperparathyroidism, a condition which remains curable with surgery.

Calcium↗

PubMed1985

[Advantages of the immunodiagnosis of bovine hypodermosis established by passive hemagglutination and by ELISA, using serum and lactoserum, over the warble count].

For an immunodiagnosis of hypodermosis, the most favourable period, December to April, was determined by means of annual kinetics of the anti-Hypoderma antibodies. From 69 blood samples, immunodiagnosis by means of a passive hemagglutination and ELISA are strictly correlated (r = 0.429, P less than 0.01). The results obtained by the ELISA technique on the serum and lactoserum of 23 cows are also correlated (r = 0.444, P less than 0.02). The immunodiagnosis of hypodermosis carried out on the serum or the lactoserum requires a single sample, contrary to the warble count which demands numerous interventions in order to be viable.

Animals↗

PubMed1985

[Comparison of the detection of foci of fascioliasis by the ELISA test on lactoserum and serum and by coproscopy].

The purpose of this investigation was to compare techniques to diagnose herds infected by Fasciola hepatica. Based on a previous survey in the slaughter houses of Côtes-du-Nord, 37 herds were selected on the frequency of condemned livers per herd. Fecal examinations and immunodiagnosis by ELISA technique were performed. Antibodies were searched for in the pooled milk of each herd and in sera of 30 to 80% of the cattle. On 9 herds without any previous condemnation, seven had a negative immunodiagnosis on pooled milk and 0 to 16% serologically positive animals. The two other herds had a suspect immunodiagnosis on pooled milk and 28 to 65% serologically positive animals. In nine herds presenting a previous liver seizure, immunodiagnosis on pooled milk were positive on eight of them. 42 to 100% of the cattle were serologically positive and 25 to 75% of the fecal examinations were positive. In 19 herds having previously two or more liver confiscations, 68 to 100% of the cattle were serologically positive, all the pooled milk were immunologically positive and just one herd, treated previously, had a 100% negative fecal examination. The results of fecal examination and immunodiagnosis are globally comparable to the slaughter house survey. Nevertheless the sensitivity of the fecal examination and more specially the immunodiagnosis is higher. The herd diagnosis based on the examination of pooled milk has a practical application in further investigation of parasitic diseases distribution in dairy herd.

Animals↗