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M C Healey

Publications and source records attributed to M C Healey.

At least 37 records · Page 2Linked to original sources
PubMed1993

The immunosuppressive effects of dexamethasone administered in drinking water to C57BL/6N mice infected with Cryptosporidium parvum.

The feasibility of immunosuppressing adult C57BL/6N mice by using dexamethasone in drinking water to sustain infections with Cryptosporidium parvum was investigated. An ethanol-soluble formulation of dexamethasone (DEX) was compared with a water-soluble (phosphated) formulation (DEXp). DEX or DEXp was provided for mice ad libitum in drinking water at dosages of 10, 33, and 100 micrograms/ml. DEX was also administered to mice by intraperitoneal injection at 125 micrograms/mouse/day. All mice were inoculated intragastrically with 10(6) C. parvum oocysts/mouse on day 14 postimmunosuppression. Mice immunosuppressed through drinking water exhibited increased signs of toxicity compared with mice intraperitoneally injected with DEX. Moreover, mice receiving DEX in drinking water were less active and died significantly sooner (P < 0.05) than mice receiving DEXp at the same dosages. Immunosuppressed mice began shedding oocysts 3 days postinfection and continued to shed until they either died or were killed. Beginning on day 12 postinfection, mice receiving DEX or DEXp in drinking water shed significantly more oocysts (P < 0.05) than mice immunosuppressed via intraperitoneal injection. Immunosuppressing mice through drinking water was comparatively simple, less traumatic than injection, and efficient with regard to time and labor.

Administration, Oral↗
PubMed1993

Effects of dehydroepiandrosterone in immunosuppressed rats infected with Cryptosporidium parvum.

Cryptosporidium parvum is a coccidian parasite that causes diarrheal disease in animals and humans. Severe cryptosporidial infections were noted in young adult rats immunosuppressed with the glucocorticosteroid dexamethasone (DEX). B-cell and T-cell responses to the mitogens lipopolysaccharide and concanavalin A, respectively, were depressed in the DEX-treated rats. In addition, DEX treatment suppressed serum IgG levels, in vitro IgG production, and natural killer cell activities. Previous results have shown that DEX-immunosuppressed rats treated with dehydroepiandrosterone (DHEA) exhibit significant reductions in cryptosporidiosis as determined by monitoring oocyst shedding in the feces and parasite colonization of the small intestine. Results from this study indicated that B- and T-cell responses to their respective mitogens, serum IgG levels, and in vitro IgG production were greater in DHEA-treated immunosuppressed rats than in untreated DEX-immunosuppressed rats infected with C. parvum. Similar results were demonstrated in DHEA-treated versus normal control rats infected with C. parvum. These results suggest that the effects of DHEA in reducing cryptosporidiosis are the result of a potentiation of the immune system in the immunosuppressed rats.

Animals↗
PubMed1992

The phototoxic effect of erythrosin B on third-stage larvae of gastrointestinal nematodes in sheep.

The phototoxic effect of erythrosin B on the infective third-stage larvae (L3) of naturally acquired mixed populations of ovine gastrointestinal nematodes was investigated. This xanthene dye was phototoxic when administered orally to parasitized lambs or applied directly to feces containing nematode ova. Phototoxicity was assessed by the lack of motility (non-swimming) exhibited by the L3 following their collection by Baermannization from cultured feces and exposure to fluorescent light for 360 min. When lambs were administered erythrosin B orally at dosages of O (control), 40, 60 and 80 mg dye kg-1 body weight daily for 10 consecutive days, the percentages of non-swimming L3 were 16%, 46%, 55% and 62%, respectively. However, erythrosin B phototoxicity did not persist after administration of the dye was discontinued and the percentage of non-swimming L3 declined to a level similar to that of the untreated controls within 2 days. The highest percentage of non-swimming L3 was observed when erythrosin B was added directly to feces containing nematode ova. A dose-response curve was evident from the successively higher percentages of non-swimming L3 with increasing concentrations of erythrosin B. Xanthene dyes have the potential to control parasites acquired by livestock on pasture by inducing a phototoxic reaction in the infective L3.

Administration, Oral↗
PubMed1992

Cryptosporidium parvum: experimental infections in aged Syrian golden hamsters.

Young (8-12 weeks) and aged (20-24 months) Syrian golden hamsters were intragastrically inoculated with Cryptosporidium parvum oocysts to compare the susceptibility to cryptosporidiosis between these two age groups. Oocyst shedding was significantly more intense in the aged than in the young hamsters. Moreover, parasite colonization of the small intestine was observed in the aged but not the young hamsters. Splenocytes from aged hamsters exhibited significantly lower T, B, and natural killer cell activities than did those from young hamsters. These studies suggest that susceptibility to cryptosporidial infections may be greater in aged individuals than has been previously realized.

Aging↗
PubMed1992

Effectiveness of dehydroepiandrosterone in reduction of cryptosporidial activity in immunosuppressed rats.

The aim of this study was to evaluate the efficacy of the immunomodulator dehydroepiandrosterone in the treatment of cryptosporidiosis in glucocorticoid-induced immunosuppressed rats. A significant reduction in cryptosporidial activity occurred in treated versus untreated rats as assessed by oocyst shedding intensities and examination of parasite colonization in the small intestine.

Animals↗
PubMed1992

Experimental Cryptosporidium parvum infections in immunosuppressed adult mice.

Five strains of adult mice were immunosuppressed with the synthetic glucocorticosteroid dexamethasone (DEX), administered either orally or intraperitoneally. The strains of mice used were C57BL/6N, DBA/2N, CBA, C3H/HeN, and BALB/cAnN. All mice were evaluated for susceptibility to Cryptosporidium parvum after intragastric inoculation with 10(6) oocysts per mouse. The DBA/2N, CBA, C3H/HeN, and BALB/cAnN mice given 0.25 micrograms of DEX per g per day orally (the dose and route previously used to infect rats with C. parvum) failed to develop chronic infections. However, the C57BL/6N mice sustained light infections during the entire 28-day experiment. The five strains of mice were also administered DEX intraperitoneally at concentrations ranging from 62.5 to 500 micrograms/day. Only the C57BL/6N mice given DEX at 125 micrograms/day developed chronic infections which persisted over 10 weeks, suggesting that the genetic background of the mouse plays a role in determining susceptibility to cryptosporidosis following immunosuppression with DEX. We believe that the C57BL/6N mouse model will prove to be superior to other animal models for evaluating potential anticryptosporidial agents, as well as for elucidating the immunological defects that allow C. parvum to establish chronic infections, because of cost effectiveness and ease in maintenance, breeding, and handling. We also evaluated the C3H/HeJ/beige mouse (lacks natural killer cell activity) and the C57BL/6N mouse maintained on a low-protein diet to induce immunosuppression. Neither of these mice exhibited heavy cryptosporidial infections.

Analysis of Variance↗
PubMed1992

Growth of hybridoma cells and antibody production in agamma calf serum.

An agamma calf serum (ACS) was compared to fetal bovine serum (FBS) and calf serum supplemented growth media for both murine and human fusion partners and derived hybridoma cells. The variables analyzed were cloning efficiencies, growth characteristics, and MAb production levels. Cultures were established in each serum source, and supernatants were kept for analysis. For cloning efficiencies, the results indicate that although there is no clear advantage in the performance of FBS-supplemented medium, ACS-supplemented RPMI 1640 medium can be used to clone hybridomas and the fusion partners. When analyzed for MAb production in the various sera, the hybridoma cell lines used in this study appeared to produce up to twice as much immunoglobulin when grown in ACS as when grown in supplemented medium. IgG- and IgM-secreting hybridoma cultures should be checked independently for antibody production. Six out of eight murine and human hybridoma cell lines produced higher levels of MAbs when grown in ACS.

Animals↗
PubMed1992

Dehydroepiandrosterone-induced reduction of Cryptosporidium parvum infections in aged Syrian golden hamsters.

Cryptosporidiosis, a parasitic disorder caused by Cryptosporidium parvum, is frequently a fulminating and life-threatening disease in immunocompromised hosts. The immune status of the host plays a critical role in determining the length and severity of the disease. Dehydroepiandrosterone (DHEA) is an immunomodulator that has been demonstrated to upregulate immune parameters. Ten aged (20-24 mo) Syrian golden hamsters were treated with DHEA for 7 days prior to intragastric inoculation with 1 x 10(6) C. parvum oocysts. An additional 10 aged hamsters were infected similarly but retained as untreated controls. The untreated hamsters presented with generalized infections as determined by oocyst shedding in the feces and parasite colonization of the small intestine. Hamsters treated with DHEA exhibited a significant reduction in cryptosporidial infection when compared to untreated hamsters. These results suggest that DHEA may be an effective prophylactic agent for cryptosporidiosis in immunocompromised patients.

Aging↗
PubMed1991

Chronic Cryptosporidium parvum infections in congenitally immunodeficient SCID and nude mice.

Severe combined immune deficient (SCID) and athymic National Institutes of Health (NIH)-III (bg/nu/xid) mice were evaluated for susceptibility to Cryptosporidium parvum infections as neonates and as adults after challenge with inocula of 5 x 10(4) and 1 x 10(6) oocysts/mouse, respectively. SCID and NIH-III nude mice developed chronic infections that persisted over 12 weeks. Cryptosporidial organisms were observed in the small and large intestines of all mice. Colonization of the gallbladder and hepatobiliary duct epithelium occurred in a majority of the NIH-III nude mice and a smaller number of the SCID mice. Severe infections in both mouse strains were associated with clinical deterioration followed by death. Signs in these mice included dehydration, icterus, and emaciation. Deaths apparently resulted from hepatic dysfunction. Control mice experienced transient infections with no clinical signs. Immunodeficient mice should prove useful in studies of disease pathogenesis and in evaluating potential anticryptosporidial agents.

Animals↗
PubMed1991

In vitro activities of lytic peptides against the sporozoites of Cryptosporidium parvum.

Cryptosporidium parvum is a protozoan parasite that causes mild to severe diarrheal disease in animals and humans. There are currently no effective chemotherapeutic agents available for the treatment of cryptosporidiosis. Recent studies have described small, naturally occurring antimicrobial lytic peptides with antiprotozoal activities. In the present study, the anticryptosporidial activities of three synthetic lytic peptides were determined in an in vitro sporozoite susceptibility assay. Sporozoite viability was assessed microscopically by the uptake of the vital dyes fluorescein diacetate and propidium iodide. Sporozoite viability was reduced by 93.5% following a 60-min exposure to 10 microM Hecate-1 at 37 degrees C. Shiva-10 reduced sporozoite viability by approximately 74.0% after a 60-min exposure at 100 microM and 37 degrees C. The cecropin-b analog SB-37 reduced sporozoite viability by 6.0% following a 60-min exposure at 100 microM and 37 degrees C. A control peptide showed no anticryptosporidial activity.

Amino Acid Sequence↗
PubMed1991

Production and partial characterization of monoclonal antibodies specific for the gamonts of Eimeria tenella.

Thirteen hybridomas secreting monoclonal antibodies (Mabs) specific for the sexual stages (gamonts) of Eimeria tenella were produced by fusing spleen cells of gamont-immunized RBF/Dn mice with FOX-NY myeloma cells. A Mab subisotype profile revealed 1 IgG2a and 12 IgG1. All Mabs demonstrated a similar binding pattern when incubated with parasitic gamonts as determined by the indirect fluorescent antibody test. Ascitic fluid containing Mab (GD9 (IgG1) was produced and used to immunize chicks passively per os. There was a 34% decrease (P less than 0.05) in oocyst output from immunized chicks when compared to control chicks. Passively immunized chicks also had reduced cecal lesion scores when compared to control chicks. These results suggest that Mab GD9 partially inhibited the fertilization process of E. tenella.

Animals↗
PubMed1991

A model for demonstrating the adhesion of Actinobacillus seminis to epithelial cells.

The objective of this study was to demonstrate that a field isolate of Actinobacillus seminis (As8C) will adhere to epithelial cells and that this adhesion can be inhibited by pretreating the bacteria with mouse serum containing polyclonal antibodies (PoAbs) prepared against this isolate. An indirect fluorescent antibody test, transmission electron microscopy, and phase-contrast microscopy confirmed the adhesion of As8C to an established culture of bovine kidney epithelial cells (BKECs). In a bacterial adhesion assay, 40 As8C were estimated to adhere to each BKEC after 60 min. Using a bacterial inhibition assay, PoAbs diluted 10(-2) or 10(-3) inhibited the adhesion of As8C to BKECs by approximately 90%. Bacterial inhibition decreased to about 50% when the PoAbs were diluted to 10(-4). There was less than 10% inhibition of adhesion of As8C to BKECs when higher dilutions of PoAbs were used. The inhibition of As8C adhesion to BKECs was less than 20% following pretreatment of BKECs with 10(-2) to 10(-5) dilutions of PoAbs. Moreover, pretreatment of As8C with a 10(-2) dilution of PoAbs did not appear to adversely affect bacterial growth on agar. It is likely that the PoAbs interrupted the adhesion of As8C to BKECs by sterically interfering with a bacterial adhesin-epithelial cell receptor interaction.

Actinobacillus↗
PubMed1990

Effect of oxamisole on immune parameters of mice infected with murine hepatitis.

The effects of Oxamisole, 2,3,5,6,7,8-hexahydro-2-phenyl-8,8- dimethoxyimidazo[1,2a]pyridine on immune parameters of mice infected with murine hepatitis were investigated. Young Swiss Webster mice were injected intraperitoneally (i.p.) with the Friend-Braunsteiner strain of murine hepatitis virus and with various doses of Oxamisole at 48 h pre- 24 h pre-, and 4 h post-virus exposure. Antiviral activity was seen in the drug-treated mice which was approximated on the basis of 21-day survival frequency and hepatic discoloration, SGOT and SGPT levels and amount of infectious virus recoverable from the liver. On day 4 post-viral exposure, splenic cells from some of the drug- and placebo-treated cells of infected mice injected with Oxamisole, 25 mg/kg/day, produced significantly more interleukin-1 and interleukin-2 than cells of infected mice treated with saline only. Similarly, mice treated with 25 mg/kg/day of this compound had cells with significantly increased antibody-dependent cell-mediated cytotoxicity as compared with placebo treated animals. However, cells from mice treated with Oxamisole did not demonstrate altered natural killer cell activity. It is concluded that Oxamisole, when administered to mice infected with murine hepatitis virus, has antiviral properties which possibly are mediated through the immunomodulatory effects of this compound on the immune system.

Adjuvants, Immunologic↗
PubMed1989

Cultural and biochemical characterization of Actinobacillus and Actinobacillus-like species from ram lambs with epididymitis.

Cellular, colonial, cultural, and biochemical characteristics of 25 field strains of gram-negative pleomorphic bacilli from rams with epididymitis were compared with Actinobacillus actinomycetemcomitans American Type Culture Collection (ATCC) strain 29522 and Actinobacillus seminis ATCC strain 15768. Three field strains were identified as A. actinomycetemcomitans, 15 as A. seminis, and 2 as Haemophilus agni; however, 5 strains (3 in group A and 2 in group B) were not identified as species in the genera Actinobacillus, Haemophilus, or Pasteurella based on the taxonomic criteria in Bergey's manual of systematic bacteriology. The 5 Actinobacillus-like organisms in groups A and B were predominantly gram-negative coccobacilli and exhibited less pleomorphism than the 2 Actinobacillus species. The colonial morphologies of groups A and B were similar to the 2 Actinobacillus species but were smaller in diameter and had a pale yellow color. Groups A and B, like the actinobacilli, were facultative anaerobic and capnophilic, did not grow on MacConkey agar, and were catalase-positive and oxidase-positive. Group A reduced nitrate but group B did not. The A. seminis strains utilized ornithine, and group A utilized arginine; but group B did not utilize either ornithine or arginine. All strains failed to utilize lysine or tryptophane. All strains produced acid but no gas from glucose, and the utilization of other carbohydrates varied markedly both between and within the 5 groups of bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinobacillus↗
PubMed1988

Purification of ascitic fluid-derived murine monoclonal antibodies by anion-exchange and size-exclusion high-performance liquid chromatography.

Ascitic fluid-derived murine monoclonal antibodies (MoAbs) of immunoglobulin (Ig) M and IgG isotypes (IgG1 and IgG2a subisotypes) were previously prepared against an isolate of Actinobacillus sp (CAs8C) for the purpose of identifying and characterizing outer membrane antigens on this bacterium. An attempt was made to purify these MoAbs by anion-exchange and size exclusion high-performance liquid chromatography (HPLC). Hybridomas producing the IgG1 and IgG2a MoAbs posed unique difficulties in that they also secreted irrelevant IgG2b MoAbs that were present in the ascitic fluids. Anion-exchange chromatography (Protein-Pak DEAE-5PW column), with a simultaneous change in gradients of pH and ionic strength, was used to purify IgG and as a first step in the purification of IgM. There was good separation of IgG2b from IgG2a, but not from IgG1. Size-exclusion chromatography (Protein-Pak 300 SW column) was required to complete the purification of IgM. The presence of MoAbs in the HPLC fractions was confirmed by discontinuous gradient polyacrylamide gel electrophoresis (denatured and either reduced or non-reduced conditions) and the enzyme-linked immunosorbent assay. HPLC-purified MoAbs were free from transferrin and albumin and retained their specificity for As8C.

Actinobacillus↗
PubMed1988

Comparison and partial characterization of the protein profiles and outer membrane antigens of Actinobacillus species isolated from ram lambs with epididymitis.

Three monoclonal antibodies (LG17, LG30, LG33) were used in the indirect fluorescent antibody test, the ELISA, and the immunoelectrotransfer blot technique to identify group-specific and strain-specific epitopes on the outer membranes of Actinobacillus seminis, A actinomycetemcomitans, and 17 field isolates of Actinobacillus spp. The field isolates had been obtained by bacteriologic culture of specimens from ram lambs with epididymitis. Only antibody LG33 consistently had specificity for an outer membrane epitope shared by most of the bacterial isolates tested. Staining of polyacrylamide gels with periodic acid-Schiff reagent, Sudan black B, and Coomassie brilliant blue R250 indicated that target antigens for antibodies LG17 and LG33 contained carbohydrate and lipoprotein components, respectively. The chemical composition of the LG30 target antigen was not determined because of its instability after exposure to sodium dodecyl sulfate. Discontinuous-gradient polyacrylamide gel electrophoresis in sodium dodecyl sulfate and spectrophotometric scans of the gels were used to analyze n-octyl-beta-D-glucopyranoside protein extracts from A seminis, A actinomycetemcomitans, and 13 representative field isolates of Actinobacillus spp. Bacterial isolates could be grouped according to their protein profiles. The first group consisted of A seminis, A actinomycetemcomitans, and 7 field isolates of Actinobacillus spp, all of which shared common protein bands with molecular masses of approximately 94 kilodaltons (kD), 64 kD, 60 kD, 52 kD, 44 kD, and 26 kD. The second group was composed of 6 field isolates, each with unique protein profiles; isolates had relatively few protein bands in common. These data suggested that members of the genus Actinobacillus cultured from ram lambs with epididymitis probably include a number of various strains.

Actinobacillus↗
PubMed1987

Comparison of treatments for ovine foot rot.

Sheep affected with foot rot were treated by vaccination and/or hour-long footsoaks, without hoof paring. The response to each treatment was obvious, but the cure rate was not satisfactory for eradication efforts. Booster vaccination and hoof paring combined with medication applied topically greatly improved the response to treatment. There was little difference in response to footsoaking or footbathing when hooves were pared.

Animals↗