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Biomedical subjects

J A Ellis

Publications and source records attributed to J A Ellis.

At least 91 records · Page 5Linked to original sources
PubMed1996

Effects of perinatal vaccination on humoral and cellular immune responses in cows and young calves.

OBJECTIVE: To examine the effects of perinatal vaccination on cellular and humoral responses in cows and on passive transfer of antibodies and cells to calves, and to assess the role of maternal antibodies in vaccination responses of neonatal calves. DESIGN: Prospective randomized control trial. ANIMALS: 52 beef cows and their calves. PROCEDURES: Assigned cows were vaccinated twice during the last month of gestation. Assigned calves were vaccinated at day 10 after birth. Antibody concentrations and cellular responses to bovine respiratory syncytial virus (BRSV) and bovine herpesvirus type 1 (BHV-1) were measured in blood and colostrum of cows and in blood of calves. Calves were assessed for passive transfer of lymphocytes. RESULTS: At parturition, serum antibody concentrations to BRSV as well as BHV-1- and BRSV-specific blastogenic responses were significantly higher in vaccinated cows. After birth, calves from vaccinated cows had significantly higher concentrations of BRSV-specific serum antibodies, but not BHV-1 specific antibodies. Calves did not develop delayed-type hypersensitivity responses to BRSV. At weaning, lymphocytes from neonatally vaccinated calves had significantly higher values for virus-specific proliferation than did lymphocytes from unvaccinated calves; however, significant differences were not detected between groups after vaccination at weaning. CLINICAL IMPLICATIONS: Administration of modified-live viral vaccines can boost systemic humoral and cellular responses to BRSV and BHV-1 in cows. Neonatal calves can be immunologically primed by vaccination with modified-live virus vaccines. Virus-specific memory cells persist in most calves until weaning.

Animals↗
PubMed1996

Analysis of monoclonal antibodies reactive with molecules upregulated or expressed only on activated lymphocytes.

Monoclonal antibodies potentially specific for antigens expressed or upregulated on activated leukocytes were selected for further analysis from the panel submitted to the third international workshop on ruminant leukocyte antigens. The kinetics of expression of these activation antigens on resting peripheral mononuclear cells (PBMC) and PBMC stimulated with concanavalin A or staphylococcal superantigen SECI for 4, 24 or 96 h were compared, as well as their appearance on various subsets of cells. For some of them, a molecular mass could be determined after immunoprecipitation from radio-labeled, lectin-stimulated cells. Based on the results from the clustering, kinetic studies and biochemical data, evidence was gathered for assigning two additional mAbs to cluster BoCD25 (IL-2 receptor) and two mAbs to cluster BoCD71 (transferrin receptor). Four mAbs recognized an early activation antigen predominantly expressed on gamma delta T cells in short-term cultures. A number of other activation antigens were further characterized.

Animals↗
PubMed1996

Comparative effects of bluetongue virus infection of ovine and bovine endothelial cells.

Bluetongue virus (BTV) infection results in disparate clinical syndromes among ruminant species. An in vitro model system of BTV/target cell interaction was developed using umbilical vein endothelial cells (EC)from fetal lambs and calves. These cells had microscopic, ultrastructural, and immunocytochemical features typical of EC. BTV infection in these cells was examined using virus binding assays, plaque assays, a whole-cell enzyme-linked immunosorbent assay, flow cytometry, electron microscopy, and a bioassay for interferon activity. EC from both species supported cytopathic BTV infections. Ovine EC bound more BTV initially and produced more virus over time, whereas bovine EC underwent more rapid lysis subsequent to infection. An ultrastructural comparison of BTV-infected ovine and bovine EC, grown as differentiated capillary-like cords on a laminin-rich matrix or as monolayers, revealed no significant interspecies differences in viral morphogenesis between 1 minute and 24 hours after infection. The intracellular distribution of BTV nonstructural protein 1, which localized to virus inclusion bodies and tubules, was identical for ovine and bovine endothelial cells. Ovine and bovine EC produced a soluble mediator of interferon activity in response to BTV infection; however, ovine EC produced higher levels of interferon activity at lower levels of infection. These findings indicate differences in BTV-EC interaction that may contribute to the pathogenesis of the severe inflammatory disease that is characteristic of clinical bluetongue disease in sheep.

Animals↗
PubMed1995

Identification and characterization of a novel protein (p137) which transcytoses bidirectionally in Caco-2 cells.

Antisera raised against detergent-extracted membrane fractions from the human intestinal epithelial cell line Caco-2 were used to screen a human colon cDNA library in a bacteriophage expression vector. This led to the identification, molecular cloning, and sequencing of a novel plasma membrane protein (p137) which was present in approximately equal amounts on the basolateral and apical surfaces of the cell. The pattern of extraction of p137 from membranes by Triton X-114 and its release from membranes after incubation with phosphatidylinositol-specific phospholipase C were consistent with it being a glycosylphosphatidylinositol-anchored membrane protein. Using antibodies raised against bacterial fusion proteins, it was shown that p137 was present on the cell surface as a reducible homodimer of 137 kDa subunits. There was constitutive release of p137 into the culture medium as a non-reducible 280-kDa entity. Pulse-chase experiments showed that newly synthesized p137 appeared at the basolateral side of a Caco-2 cell layer before appearing at the apical domain. Domain-specific surface biotinylation of Caco-2 cells at 4 degrees C, followed by chasing at 37 degrees C, demonstrated that p137 is capable of transcytosing in both directions across Caco-2 cells. The unusual plasma membrane domain distribution of this glycosylphosphatidylinositol-linked protein and its transcytosis characteristics demonstrate the existence of a previously uncharacterized apical to basolateral transcytotic pathway in Caco-2 cells.

Adenocarcinoma↗
PubMed1995

Cellular and antibody responses to equine herpesviruses 1 and 4 following vaccination of horses with modified-live and inactivated viruses.

The ability of monovalent and bivalent equine herpesvirus (EHV) vaccines to stimulate cellular and antibody responses to EHV-1 and EHV-4 was compared in healthy horses. Comparison of data from lymphocyte blastogenesis tests in which live viruses were used as antigens and that were conducted prior to vaccination and after 2 vaccinations revealed that horses given modified-live EHV-1 had significant increases in proliferative responses to EHV-1 (P = 0.03) and EHV-4 (P = 0.04). Responses to EHV-1 and EHV-4 in horses given the inactivated-virus bivalent vaccine were less; however, significant differences were not noticed when postvaccinal lymphocyte blastogenesis tests were compared between the groups of vaccinees. Interleukin-2 activity was not detected in leukocyte cultures from either group of vaccines following stimulation with live EHV-1 or EHV-4; however, interferon activity was found in similar cultures from both groups of vaccinees. For EHV-4, interferon activity in cultures from both groups of vaccinees was significantly (P < 0.05) greater than that in leukocyte cultures from unvaccinated controls. Both vaccines induced significant (P < 0.05) increases in serum antibodies that neutralized EHV-1 infectivity. The ELISA for EHV-1 and EHV-4 antibodies revealed that both vaccines induced significant (P < 0.05) increases (compared with preinoculation values) in antibodies reactive with these 2 types of EHV. Total serum antibody responses, as measured by ELISA, to EHV-1 and EHV-4 were significantly (P < 0.05) higher in horses that received the bivalent inactivated-virus vaccine, compared with that in horses that received monovalent vaccine. Evaluation of these data revealed that vaccination with modified-live EHV-1 can stimulate cellular and antibody responses that cross-react with EHV-4.

Analysis of Variance↗
PubMed1995

Bovine respiratory syncytial virus-specific immune responses in calves after inoculation with commercially available vaccines.

A study was designed to determine if inactivated bovine respiratory syncytial virus (BRSV) vaccines induce the same types of antibody and cellular responses as does a modified-live BRSV vaccine. Ninety mixed-breed, 5- to 6-month-old beef calves were randomly assigned to 1 of 6 groups with 15 animals/group. Calves in 5 of the groups were inoculated on days 0 and 14 with 1 of 4 inactivated virus vaccines or with a modified-live virus vaccine. The remaining 15 calves were maintained as unvaccinated controls. Immune responses were measured on days 0 and 24, by means of ELISA, virus neutralization assay, blocking ELISA for the BRSV fusion (F) protein, immunoblotting, and lymphocyte blastogenesis assay. All vaccines induced production of antibodies that recognized the F protein; however, the ratio of neutralizing antibody titer to change in BRSV-specific IgG antibody concentration (as determined by use of ELISA) was lower for calves that received an inactivated virus vaccine than for calves that received the modified-live virus vaccine. All of the vaccines induced lymphocyte proliferative responses to BRSV. Results suggest that commercially employed inactivation processes can alter functionally important epitopes on BRSV envelope glycoproteins, leading to production of predominantly nonneutralizing antibodies in immunized cattle.

Animals↗
PubMed1995

Response of the regional lymph node to bluetongue virus infection in calves.

Bluetongue virus (BTV) infection of cattle is characterized by prolonged cell-associated viremia. In an effort to further evaluate the antiviral response of BTV-infected cattle, the role of the regional lymph node (LN) in the immune response of calves to BTV was characterized. Calves were inoculated with BTV in the skin of the neck in an area drained by the superficial cervical LN. Calves were euthanized at regular intervals after inoculation and both BTV-challenged and contralateral (control) superficial cervical LNs were harvested. In addition, some calves had cannulation of the superficial cervical efferent lymphatics prior to inoculation. Lymphocyte subpopulation analysis was done on LN cell suspensions and lymph cells using a panel of cell-specific monoclonal antibodies. There was a significant increase in the proportion of B cells in the challenged LN after inoculation as compared with the control LN. In addition, BTV-specific antibodies were detected in efferent lymph plasma from the challenged LN in one cannulated calf by 9 days after inoculation (DAI), as determined by competitive enzyme-linked immunosorbent assay, whereas BTV-specific antibodies were not detected in serum from this calf through 12 DAI. Analysis of lymph cells revealed a sustained increase in cell output from the challenged LN due to an increase in lymphoblasts and CD8+ T cells. In contrast, the cell output from the control LN dropped markedly by 8 DAI and there was no significant increase in any specific cell population. Double label analysis characterized lymphoblasts as activated CD8+ cells, as determined by expression of MHC Class II antigens (CD8+ MHC II+). These cells were only transiently present as CD8+ MHC II+ cells were not identified in lymph from the challenged LN at 14 DAI. Few CD8+ MHC II+ cells were identified at any time in lymph from the control LN or in lymph from a mock infected calf. The data indicate that B cell proliferation in the challenged LN and release of activated CD8+ cells from this LN were specific responses to BTV infection. The rapid expansion of activated CD8+ T cells indicates that these cells may limit early viral spread. It is concluded that the regional LN draining inoculated skin is critical to the immune response of calves to BTV infection.

Animals↗
PubMed1995

Local production of tumor necrosis factor-alpha in corynebacterial pulmonary lesions in sheep.

Corynebacterium pseudotuberculosis infection is a common cause of pyogranulomas in ovine lungs and often occurs as a dual infection with lentiviruses. This coinfection usually leads to the development of chronic pneumonia and cachexia that is similar to the clinical syndrome seen in human beings with AIDS-related pneumonias. Recent in vitro studies indicate that monokines such as tumor necrosis factor-alpha (TNF alpha) are induced by C. pseudotuberculosis, suggesting that TNF alpha is involved in the pathogenesis of corynebacterial lesions in vivo. To substantiate in vitro observations concerning bacterial induction of TNF alpha in ovine pulmonary macrophages, immunohistochemical labeling techniques were used in combination with in situ hybridization to identify TNF-producing cells in corynebacterial lesion sites in vivo. TNF alpha message and translation product were found in macrophages comprising pyogranulomas that were induced by naturally acquired and experimental pulmonary C. pseudotuberculosis infections.

Animals↗
PubMed1995

Development and application of a microneutralization ELISA for the detection of antibodies to bovine respiratory syncytial viruses.

A microneutralization enzyme-linked immunosorbent assay (ELISA) was developed to detect specific antibodies to bovine respiratory syncytial viruses (BRSVs) in cattle sera using a monoclonal antibody to the fusion protein of the virus. Serum from 20 naturally exposed, 24 experimentally infected, and 15 immunized cattle were evaluated using 3 different BRSV isolates. Antibody titers determined with the microneutralization ELISA were compared with those derived from a classical virus neutralization assay, an indirect ELISA, and a fusion inhibition assay. These studies demonstrated a high degree of correlation (usually 0.90) among the assays. Furthermore, the results showed that immunization of cattle with one isolate (subgroup) of BRSV induced antibody responses that cross-reacted with at least 2 disparate isolates. These results document the utility of the microneutralization ELISA in assessing functionally important antibody responses to BRSVs in cattle.

Animals↗
PubMed1995

Comparison of detection methods for bovine viral diarrhea virus in bovine abortions and neonatal death.

The objective of this study was to examine a monoclonal antibody-based immunohistochemical staining method for its efficacy in diagnosis of bovine virus diarrhea virus (BVDV)-induced abortion and neonatal calf death. This method was compared to viral isolation and immunofluorescence staining of frozen tissue sections. Tissues from 105 cases, 53 fetuses and 52 neonates, were tested by the 3 methods. There were significant numbers of both false negatives and false positives with the immunofluorescence method and significant numbers of false negatives with the viral isolation method. Of the methods tested, immunohistochemical staining using monoclonal antibody 15C5 performed best, differentiating 97% of positive and negative cases. These results indicated that immunohistochemical staining can be applied to improve the accuracy of BVDV diagnosis in cases of abortion and perinatal death.

Abortion, Veterinary↗
PubMed1994

Effect of selected cytokines on the replication of Corynebacterium pseudotuberculosis and ovine lentiviruses in pulmonary macrophages.

Opportunistic bacterial pathogens that induce monokine secretion by pulmonary alveolar macrophages (PAM) are frequently encountered complicating factors in lentivirus-associated pneumonias in ungulates and man. We examined the effect of selected cytokines on the replication of Corynebacterium pseudotuberculosis and ovine lentivirus (OvLV) in ovine PAM. Recombinant bovine (rBo) IL 1 beta, rBoIL-2, rBo interferon-gamma (IFN gamma) and rBoTNF alpha, alone and in combination at physiological doses had no apparent effect on the extracellular growth of C. pseudotuberculosis, compared with the growth of the pathogen in medium alone. Untreated ovine PAM, derived from bronchoalveolar lavage, were found to substantially reduce, but not eliminate the growth of C. pseudotuberculosis in culture. This bactericidal effect was neither enhanced nor inhibited by pretreatment of PAM with the recombinant bovine cytokines or low doses of LPS that induce monokines. In contrast, addition of rBoTNF alpha or rBoIL-1 beta, at physiological doses, at the initiation of, or on Day 4, after OvLV infection resulted in a significant increase in viral replication in PAM, as measured in an antigen capture assay for OvLV p25, compared with untreated infected cells. This effect was more pronounced with lower levels of infecting OvLV, and, in the case of TNF alpha, was abrogated by preincubation of the cytokine with specific anti-serum. Conversely, in most instances, inclusion of rBoIFN alpha in OvLV-infected PAM cultures resulted in a significant decrease in viral replication. These results suggest that these soluble mediators that are probably secreted in response to C. pseudotuberculosis infection may have little direct effect on the extra- or intracellular survival of the bacteria in the lung, but may modulate lentiviral replication and, by extension, disease expression, in sheep with dual infection.

Animals↗
PubMed1994

Analysis of seating and fracturing torque of bicortical screws.

The purpose of this study was to analyze and compare the seating and fracturing torque of 2.0-mm- versus 2.7-mm-diameter titanium screws. Six cadaver mandibles were sectioned at the symphysis and 20 drill hole locations were chosen on each half. Half the holes were designated for the 2.0-mm screws, tapped and nontapped, and the remaining half for 2.7-mm screws, tapped and nontapped. The maximum torque leading to the screw seating or fracturing was recorded using an electric torque tester (Artech Reliance, Chantilly, VA). The mean maximum seating torque for the 2.7-mm screws, tapped and nontapped, was 30% of that measured for the 2.0-mm screws. The mean maximum seating torque for all tapped screws was 35% less than for all nontapped screws. The region of the mandible requiring the greatest seating torque was the symphysis, followed by the body, condyle, ramus, and angle. None of the 2.7-mm screws fractured; however, 10% of the 2.0-mm screws fractured. Three were located in the symphysis and one in the ramus. With the 2.0-mm screws that did not fracture, the seating torque in the nontapped holes was 59% greater than in the tapped holes. With the 2.0-mm screws that fractured, the mean maximum fracturing torque was 64% greater than for those screws that did not fracture. This study shows that small screws placed in the mandible require greater seating torque, regardless of whether the holes are tapped, and that there is an increased chance of small screws fracturing in certain regions.

Bone Density↗
PubMed1994

Cognitive-behavioral interventions for children's distress during bone marrow aspirations and lumbar punctures: a critical review.

Children with cancer often have difficulty coping with the invasive medical procedures that are part of diagnosis and treatment. Bone marrow aspirations and lumbar punctures are painful and cause some children severe anxiety and distress. The increased risk and expense of general anesthesia and the relative ineffectiveness of sedatives and anxiolytics has prompted clinicians to examine nonpharmacologic methods for controlling pain and distress. This report critically examines intervention studies that focus on cognitive-behavioral strategies such as distraction, imagery, or hypnosis for reducing procedural distress in children with cancer.

Analgesia↗
PubMed1994

Special tests for the diagnosis of infectious causes of reproductive failure in ruminants.

The detection of many infectious disease agents, including those of importance in ruminant reproductive failure, increasingly will be achieved through means other than the laborious and time-consuming traditional isolation and culture procedures. New diagnostic methodologies are designed both to enhance the rapidity with which results are obtained and to increase specificity and sensitivity of identification of the causative agent. Immunoenzyme histochemical staining of formalin-fixed paraffin-embedded tissues offers, especially in cases of abortions in which necropsy material routinely is examined histologically, an efficient and timely means of identifying many important pathogens. Antemortem serologic diagnostics will continue to be dominated by ELISA technologies. In the past decade, the specificity of serodiagnosis has been enhanced greatly by the use of monoclonal antibody-based competitive ELISA systems and further improvements in such methods will result from the use of defined antigens derived by recombinant DNA techniques. Although DNA hybridization technology has been applied successfully to detect many important veterinary pathogens and has been shown to have merit for improved diagnosis of some fastidious agents, those methods, because of their technical complexity, in general, have not been shown to be applicable for routine diagnostic uses. In contrast, methods using the PCR for specific gene amplification offer exceptional promise. Although the PCR presently is too technically exacting for routine use, its broad applicability and exquisite sensitivity and specificity suggest that it will play an ever-increasing role in future veterinary diagnostic techniques.

Abortion, Veterinary↗