Search PubMed⌕ Search

Biomedical subjects

L B Corbeil

Publications and source records attributed to L B Corbeil.

At least 73 records · Page 4Linked to original sources
PubMed1988

Purification and characterization of lipooligosaccharides from four strains of "Haemophilus somnus".

Lipooligosaccharides (LOSs) from four strains of "Haemophilus somnus" were purified and their electrophoretic profile, composition, endotoxic activity, and antigenic properties were analyzed. The LOSs were most efficiently purified by enzyme digestion, hot aqueous phenol extraction, and ultracentrifugation. Each LOS could be separated into two to six distinct bands with apparent Mrs of 3280 to 4960, following electrophoresis in polyacrylamide gels. Each LOS contained dodecanoic, tetradecanoic, and 3-hydroxytetradecanoic fatty acids; a high proportion of hexose, 3-deoxy-D-manno-octulosonic acid, and phosphate; and a small amount of heptose; glucosamine was present in both the oligosaccharide and the lipid A. Each "H. somnus" LOS demonstrated endotoxic activity, as determined by gelation of Limulus ameobocyte lysate, the dermal Schwartzman reaction, and mouse lethality. Antiserum to purified "H. somnus" LOS cross-reacted with all strains of "H. somnus" tested by enzyme-linked immunosorbent assay (ELISA), but not to any Enterobacteriaceae, Pseudomonas, or Pasteurella species tested. "H. somnus" LOS was a poor immunogen, but inhibition, dot blot, and sandwich ELISA data indicated that antibodies made to LOS were predominantly, though not exclusively, to lipid A. Monoclonal antibodies directed to "H. somnus" LOS confirmed that lipid A and non-lipid A determinants were present.

Animals↗
PubMed1988

Killing of Brucella abortus by bovine serum.

Studies of the serum bactericidal system in bovine brucellosis were undertaken to investigate the role of the humoral immune response in protection of cattle against the facultative intracellular parasite Brucella abortus. Fresh sera from normal control cattle, infected cattle, and cattle immunized with B. abortus cell envelopes were collected before treatment and during the course of immunization or infection. Normal fresh bovine serum or fresh agammaglobulinemic serum from colostrum-deprived calves was effective in killing smooth virulent B. abortus 2308, but rough strains RB51 (a rough mutant of strain 2308) and 45/20 were much more sensitive to serum. The difference in susceptibility to serum was shown to be correlated with differences in lipopolysaccharide chemotype, with the more resistant strain 2308 having O polysaccharide and the more susceptible strains 45/20 and RB51 lacking O side chains. By treatment of fresh serum with MgCl2 and EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] killing was shown to occur via the classical pathway of complement activation. When antibody to B. abortus was present, killing of strain RB51 increased but killing of smooth strain 2308 decreased. The earliest antibody response in serum from infected animals did not interfere with killing. When affinity-purified bovine immunoglobulins specific for B. abortus smooth lipopolysaccharide were added to fresh normal bovine serum, immunoglobulin G1 (IgG1) and IgG2 isotypes blocked killing but IgM and IgA isotypes did not. Thus, it appears that serum from previously unexposed animals or animals early during infection can kill smooth B. abortus, an appropriate defense mechanism before the organism becomes intracellular. At later stages of infection, blocking antibodies predominate.

Animals↗
PubMed1988

Protective ability of antibodies against 78- and 40-kilodalton outer membrane antigens of Haemophilus somnus.

The ability of concentrated antibody against the 78- or 40-kilodalton (kDa) outer membrane protein (OMP) of Haemophilus somnus to passively protect calves against H. somnus-induced pneumonia was determined. The 78- and 40-kDa OMPs were evaluated in passive protection experiments, because results of previous studies demonstrated their (i) immunogenicity for cattle, (ii) intense reactivity with convalescent-phase sera which passively protected calves against experimental H. somnus pneumonia, (iii) surface location and accessibility to antibody, and (iv) conservation among a wide range of H. somnus isolates obtained from animals with different diseases and from different geographic locations. The specificity of the two antisera evaluated in this study was verified by (i) immunoblots in which reactivity against the 78- or 40-kDa OMP was present in postimmunization but not preimmunization serum and (ii) immunoblots in which affinity-purified, surface-reactive antibodies in each antisera were used, which demonstrated that essentially only antibody to the 78- or 40-kDa OMP was reactive with the surface of H. somnus. In enzyme-linked immunosorbent assays, the antiserum against the 40-kDa OMP contained immunoglobulin G1 (IgG1), IgG2, and IgM against H. somnus, while the antiserum against the 78-kDa OMP contained IgG1 and IgM but no IgG2 against H. somnus. The antiserum against the 40-kDa OMP contained IgG1 and IgG2 specific for the 40-kDa OMP, as determined by Western blot analysis. Slight reactivity against H. somnus lipopolysaccharide was detected by enzyme-linked immunosorbent assay but not by Western blot analysis. In passive protection experiments, preincubation of bacteria with antibody against the 40-kDa OMP protected calves (P less than 0.025) against H. somnus pneumonia, while antibody against the 78-kDa OMP failed to protect calves against H. somnus pneumonia. Determination of the potential protective capacity of the 78-kDa OMP awaits resolution of the role of anti-78-kDa IgG2 in protection against H. somnus pneumonia. The 40-kDa OMP is, however, a good candidate antigen for evaluation of protective ability against H. somnus pneumonia following active immunization.

Animals↗
PubMed1988

Rabbit pasteurellosis: induced disease and vaccination.

Pasteurellosis was induced in rabbits by conjunctival inoculation with 2 strains of Pasteurella multocida. The LD50 of strain P1062 (a bovine isolate) was 10(5.1) colony-forming units and that of strain P1059 (a turkey isolate) was 10(5.5) colony-forming units. Pasteurella-free rabbits were vaccinated IV or mucosally with boiled cells of P multocida or a cross-reactive uridine diphosphogalactose epimerase-deficient mutant of Escherichia coli J5. In rabbits challenge exposed with P multocida strain 1062 or 1059, homologous P multocida strain gave the best protection against fatal bacteremia. Partial protection was provided by J5; mucosal routes of vaccination (aerosol or conjunctival) gave better protection than did the IV route. Serum antibody titers were lower in rabbits vaccinated by mucosal routes than in those vaccinated IV. Cross-reactive IgG and IgM titers to P multocida were demonstrated when rabbits were vaccinated with J5. On the basis of bacteriologic examination of nasal secretions, rabbits that died were considered culture positive sooner than were those that survived. On the basis of bacteriologic examination of blood, rabbits that died were considered culture positive, and those that survived were considered culture negative. Seemingly, heat-stable antigens were protective, the cross-reactive E coli J5 mutant (with only core lipopolysaccharide) provided partial protection against pasteurellosis, and the mucosal route was somewhat useful for cross-protective immunization.

Animals↗
PubMed1988

Function of phagocytes obtained from lacteal secretions of lactating and nonlactating cows.

Phagocytes, macrophages and neutrophils, were obtained from lacteal secretions of lactating (n = 13) and nonlactating cows (n = 14). Secretions from nonlactating cows were collected at 7 and 14 days after cessation of lactation. Phagocytes were incubated in vitro with Staphylococcus aureus or Escherichia coli, and function was assessed by fluorescent microscopy of cell suspensions stained with acridine orange and crystal violet. A greater percentage of macrophages from nonlactating cow secretions collected on day 14 phagocytized bacteria than did those collected on day 7. A greater percentage of macrophages from nonlactating cow secretions collected on days 7 and 14 phagocytized bacteria than did neutrophils obtained from the same secretions. A similar percentage of phagocytes from nonlactating cow secretions phagocytized bacteria, compared with phagocytes from lactating cow secretions. Results indicated that the intramammary macrophage may be most important in defense of the mammary gland during the early nonlactating period, because it was more phagocytic than the neutrophil and was more active at 14 days than at 7 days into the nonlactating period.

Animals↗
PubMed1987

Cross-reactive antibody in immunity to colisepticemia in calves.

Cattle were immunized with a uridine diphosphate galactose epimerase deficient mutant of Escherichia coli to prepare antiserum cross-reactive with different serotypes of E. coli. Hypogammaglobulinemic calves were given bovine anti-J5 serum before oral challenge with virulent E. coli derived from a septicemic calf. Passively immunized calves had delayed and decreased bacteremia compared with calves given saline before challenge. Calves given antiserum also lived longer than control calves. A second experiment using ampicillin and antibody to treat colisepticemia also showed increased survival in anti-serum-treated calves. Decreased bacteremia was probably not due to the killing of the challenge strain by antibody and complement, as the strain was serum-resistant. However, anti-J5 serum did increase phagocytosis of the challenge strain of E. coli (JL9) by bovine neutrophils. Thus, partial protection by antiserum was probably due to increased clearance of bacteria as well as neutralization of endotoxin.

Ampicillin↗
PubMed1987

Antigenic specificity of convalescent serum from cattle with haemophilus somnus-induced experimental abortion.

The antigens of Haemophilus somnus recognized by convalescent bovine serum were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting with a protein A-peroxidase conjugate. The same two 76K and 40K antigens were predominant in whole-bacterium preparations and in outer-membrane-enriched, Triton X-100-insoluble fractions. The surface location of these two antigens was confirmed by absorbing antiserum with whole, live bacteria. Absorption with H. somnus removed antibody reactivity for the 76K antigen and reduced reactivity for the 40K antigen. Absorption with Pasteurella multocida, Actinobacillus equuli, or Escherichia coli did not reduce reactivity, and results with Pasteurella haemolytica were equivocal. The two immunodominant antigens detected in this study were conserved in isolates of H. somnus from thromboembolic meningoencephalitis, pneumonia, reproductive failure, or asymptomatic carriers. Convalescent sera from nearly all 17 cattle studied recognized these two antigens. Other antigens were recognized less consistently. Although other antigens may also be involved, the 76K and 40K surface antigens of H. somnus appear to be important candidates for a subunit vaccine or an immunodiagnostic assay.

Abortion, Veterinary↗
PubMed1987

Protective ability and specificity of convalescent serum from calves with Haemophilus somnus pneumonia.

The ability of convalescent serum to passively protect calves against Haemophilus somnus-induced pneumonia was studied. Preimmune and convalescent serum were obtained from calves before or after recovery from experimental chronic H. somnus pneumonia. Passive protection was assessed in another group of calves by intrabronchial inoculation of H. somnus that had been incubated with preimmune or convalescent serum. Each calf was inoculated with each treatment in alternating caudal lung lobes. Twenty-four hours after inoculation almost no pneumonia was present in lungs inoculated with bacteria incubated with convalescent serum, whereas severe pneumonia was present in lungs inoculated with bacteria incubated with preimmune serum. Quantitation of calf pneumonia in both treatment groups indicated a significantly different protective capacity between convalescent serum and preimmune serum (P less than 0.0005). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western blotting of purified H. somnus lipopolysaccharide resulted in intense reactivity with convalescent serum, but no reactivity was detected with preimmune serum. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis of H. somnus outer membrane-enriched fractions, Western blots with convalescent serum gave intense reactions against H. somnus outer membrane antigens with apparent molecular masses of 78 and 40 kilodaltons and weaker reactions with 60-, 34-, 31-, 29-, 18-, and 15-kilodalton outer membrane antigens. No reactivity was detected with preimmune serum. Antibodies eluted from H. somnus after adsorption of convalescent serum reacted almost identically to unadsorbed convalescent serum in Western blots against bacterial outer membrane-enriched fractions. Thus, most of the antigens recognized by convalescent serum are likely to be on the bacterial surface and accessible to antibody. Surface antigens recognized by protective convalescent serum are candidate antigens for a subunit vaccine against H. somnus pneumonia.

Animals↗
PubMed1987

Experimental Haemophilus somnus pneumonia in calves and immunoperoxidase localization of bacteria.

Pneumonia was produced in nine, conventionally reared calves by intrabronchial inoculation with Haemophilus somnus. Volumes of pneumonic lung were determined stereologically, following serial slicing of lungs fixed by vascular perfusion. Twenty-four hours after inoculation, consistent findings were: neutrophilic to fibrinoid vasculitis, degeneration of alveolar macrophages, necrotizing bronchiolitis, suppurative bronchopneumonia, lobular necrosis, and dilation and thrombosis of lymphatics. Bacteria were identified histologically by an immunoperoxidase technic and were either free in alveoli or associated with degenerative alveolar macrophages. The latter suggests that macrophage degeneration may be a result of bacteria/macrophage interaction. Immune complex deposition is unlikely to be the principal mechanism for the vasculitis because bacterial antigen was not generally found in necrotic vessel walls, and two colostrum-deprived, H. somnus antibody-negative calves also had neutrophilic vasculitis 12 to 24 hours after inoculation with the lowest dose of H. somnus used in the above experiment.

Animals↗
PubMed1987

Serum susceptibility of bovine pasteurellas.

In this study, the serum sensitivity of 23 P. haemolytica isolates and 18 P. multocida isolates was determined by incubating dilutions of bacteria with equal volumes of fresh or heat-inactivated bovine serum for one, two, or three hours. Clinical isolates of both Pasteurella species were resistant to serum, whereas isolates from asymptomatic cattle varied in serum susceptibility. The classical pathway of complement appeared to be the principal means of complement mediated killing as detected by incubation in the presence or absence of EGTA-MgCl2. Lyzozyme and iron saturation of serum did not greatly affect serum susceptibility with either of the Pasteurella species.

Animals↗
PubMed1987

In vitro growth inhibition of mastitis pathogens by bovine teat skin normal flora.

One factor contributing to differences in the susceptibility of cows to mastitis may be differences in the teat skin normal flora, which could inhibit or enhance the growth of pathogenic bacteria. Using in vitro cross-streaking methods, we found that 25% of the isolates of teat normal flora of non-lactating heifers inhibited the growth of selected mastitis pathogens, but enhancers were not detected. Gram-positive pathogens were inhibited to a greater extent than Gram-negative pathogens. Inhibition was not a characteristic of specific genera or species of normal flora, but rather a property of certain variants within a species. This phenomenon of inhibition of mastitis pathogens in vitro by normal flora may be useful as an in vivo biological control method to reduce the incidence of mastitis.

Acinetobacter↗
PubMed1987

Development of a defined medium for Haemophilus somnus isolated from cattle.

Nutritional factors that influence the growth of Haemophilus somnus were examined, and a defined medium was developed. Optimal growth of H somnus in broth occurred under conditions of maximum aeration. Nutritional components required for or enhanced growth of most H somnus isolates in the defined medium included uracil, D-glucose, isotonic NaCl, Na2HPO4, nicotinamide, flavin mononucleotide, pantothenic acid, pyridoxine, and a variety of salts and amino acids. The defined medium supported optimum growth of 18 of 21 isolates of H somnus from cattle.

Aerobiosis↗
PubMed1986

Experimental abortion and the systemic immune response to "Haemophilus somnus" in cattle.

"Haemophilus somnus" has been identified in the etiology of bovine abortion on the basis of the isolation of the organism from aborted fetal and placental tissues. To investigate the role of hematogenous dissemination of "H. somnus" in the pathogenesis of abortion and to monitor the humoral immune response to infection, 19 pregnant cows (gestation ages, 1.4 to 7 months) were challenged intravenously (11 cows) or intrabronchially (8 cows). Five cows challenged intravenously aborted, and one cow challenged intrabronchially resorbed her fetus. "H. somnus" was isolated in large numbers from aborted tissues, and placental lesions were similar to those reported in a field case of "H. somnus" abortion. Antibody titers in serum were measured by the microagglutination test (MAT) and by enzyme-linked immunosorbent assay (ELISA). A response to challenge was measured by MAT; it was also measured by ELISA within the immunoglobulin G1 (IgG1), IgG2, and IgM isotypes. On comparison of pre- and postchallenge antibody titers, the greatest and most persistent response was detected within the IgG2 isotype. Prechallenge antibody titers (measured by MAT and by IgG2 ELISA) were lower in animals that aborted than in normal calving animals, indicating that IgG2 antibody may have a role in limiting hematogenous dissemination of "H. somnus."

Abortion, Veterinary↗
PubMed1986

Endotoxemia in horses: protection provided by antiserum to core lipopolysaccharide.

An equine antiserum to core lipopolysaccharide was produced by inoculation of 6 horses with a boiled cell bacterin made from the J-5 mutant of Escherichia coli O111:B4. The antiserum immunoglobulin G titer to J-5 mutant E coli, as determined by enzyme-linked immunosorbent assay, was 1:15,006. Pooled serum prepared before inoculation (preimmune serum) had a J-5 immunoglobulin G titer of 1:350. The J-5 antiserum was tested for its protective efficacy in sublethal endotoxemia in 14 horses. Four horses served as nontreated controls and were given nothing before endotoxin challenge exposure (10 micrograms/kg of body weight, IV). Pooled preimmune serum (3 ml/kg, IV) was administered to 5 horses and J-5 antiserum (3 ml/kg, IV) was administered to 5 other horses 2 to 15 hours before endotoxin challenge exposure. During the 24 hours postendotoxin challenge exposure, endotoxemia was accompanied by significant (P less than 0.05) time-related changes in temperature, heart rate, pulse character, respiratory rate and character, capillary refill time, mucous membrane color, fecal composition, attitude, PCV, total plasma protein, WBC count, platelet count, plasma fibrinogen, prothrombin time, activated partial thromboplastin time, fibrinolytic degradation products, plasma glucose, and plasma lactate in all horses. There were no apparent treatment vs time interactions (P greater than 0.05). Two horses (1 control and 1 given J-5 antiserum) died suddenly from unknown causes immediately after endotoxin challenge exposure. Seemingly, equine antiserum to core lipopolysaccharide did not provide protection from the adverse effects of experimental endotoxemia produced by bolus IV infusion of 10 micrograms of endotoxin/kg.

Animals↗
PubMed1986

Endotoxin-induced changes in the hemostatic system in neonatal calves: the effect of antiserum to a mutant Escherichia coli (J-5).

Changes in the hemostatic system were studied in 22 neonatal calves given a small dosage of Escherichia coli endotoxin (0.5 microgram/kg) by slow (5-hour) IV infusion. The effect of pretreatment with an antiserum to mutant of E coli O111:B4 (J-5) was evaluated. The platelet count, plasma fibrinogen concentration, prothrombin time, and activated partial thromboplastin time changed significantly from base line during and after endotoxin infusions in all calves. The mean platelet count was significantly decreased from 1 through 24 hours after endotoxin infusion was started. Mean plasma fibrinogen was decreased 2 through 12 hours after endotoxin infusion was started. The mean prothrombin time and activated partial thromboplastin time were significantly greater than base line at 3 to 6 hours and 3 to 12 hours, respectively, after endotoxin infusion was started. Serum concentration of fibrinolytic degradation products remained less than 10 micrograms/ml. Bovine J-5 antiserum did not prevent the endotoxin-induced changes in the hemostatic system of these neonatal calves.

Animals↗
PubMed1986

Endotoxemia in neonatal calves given antiserum to a mutant Escherichia coli (J-5).

Endotoxemia was characterized in neonatal calves given a small amount of colostrum and smooth Escherichia coli endotoxin by small-dosage (0.5 microgram/kg of body weight), slow (5-hour) IV infusion to mimic natural conditions. Responses were compared among 22 calves freely allotted to groups treated with saline solution (group I), preimmunization plasma (PP, group II), or antiserum to the rough mutant of E coli O111:B4 (J-5, group III) before endotoxin was infused. Bovine J-5 antiserum was produced by immunization of 4 cattle with J-5 boiled cell bacterin. The antiserum titers of immunoglobulin (Ig) M, IgG1, and IgG2 to the J-5 boiled cells, as determined by enzyme-linked immunosorbent assay, were 240, 7,680, and 960, respectively. The PP had enzyme-linked immunosorbent assay titers to J-5 of 240, 480, and 60 of IgM, IgG1, and IgG2, respectively. Endotoxemia in the 3 groups was characterized by significant (P less than 0.05) time-related changes in rectal temperature, heart rate, respiratory rate, capillary refill time, oral mucous membranes, nose moistness, scleral injection, attitude, PCV, total plasma protein concentration, WBC count and differential, plasma glucose, and lactate concentrations. The only significant treatment effects on clinical or laboratory values were higher mean total plasma protein concentrations in groups II and III 10 to 30 hours after endotoxin infusion was started than that in group I and increasing mean most-severe attitude abnormality score in groups I, III, and II (P less than 0.05). The administration of bovine J-5 antiserum to neonatal calves resulted in significantly higher serum IgG1 and IgG2 titers to J-5 boiled cells (P less than 0.05), and cross-reactive IgG2 to the challenge endotoxin (P less than 0.01) than did treatment with PP or saline solution; however, this antiserum did not mitigate the effects of sublethal endotoxemia. There was a significant negative correlation between IgG2 to J-5 at base line and the mean attitude abnormality score at 4.5 hours after infusion was started (P less than 0.05).

Animals↗
PubMed1985

Ultrastructure of cyclic changes in the murine uterus, cervix, and vagina.

The regional and cyclic changes in the murine genital epithelium were studied by transmission and scanning electron microscopy to provide a morphological standard to serve as a basis for investigation of host-parasite relationships in genital infections. Thus, we examined not only mucosal epithelial cell changes, but also surface mucus, normal flora and inflammatory cells. Ultrastructurally, at proestrus/estrus, we found uterine and most cervical epithelial cells covered with microvilli overlaid with mucus-like secretions and evidence of internal secretory activity. There was little normal flora anywhere in the tract. At early metestrus, we found squamous cervicovaginal epithelial cells with low discontinuous microrugae, extensive normal flora and many neutrophils beginning to migrate through the epithelium. The flora and neutrophils could explain the relative lack of susceptibility to infection at that time. At diestrus the appearance of a newly regenerated epithelium and lack of normal flora suggested that initiation of infection could occur at this stage; however, the presence of large numbers of neutrophils ready to phagocytize invading bacteria indicated a deterrent to infection. This study of cyclic changes in flora, mucus, neutrophils and epithelial cells provided ultrastructural evidence to support an earlier hypothesis that the greatest susceptibility to gonococcal infection in mice occurred at proestrus/estrus.

Animals↗