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Biomedical subjects

E Cox

Publications and source records attributed to E Cox.

At least 19 recordsLinked to original sources
PubMed2000

Identification of Ostertagia ostertagi specific cells in bovine abomasal lymph nodes.

To investigate the contribution of different bovine cell subpopulations in the development of in vitro induced responses by Ostertagia ostertagi third larval antigen extract (L3), bovine abomasal lymph node cell suspensions were depleted of specific cell populations. The depleted cell suspensions were subsequently assayed for their proliferative responses to O. ostertagi L3 antigen extract. Proliferative responses to O. ostertagi L3 antigen extract were restricted to a CD2+ CD4- CD8- cell population and MHC II+ cells different from B-cells were of major importance. Depletion of CD4, CD8, CD4CD8, IgM or CD21 positive cells did not decrease proliferation to L3 antigen extract. Depletion of gammadelta T-cells, which also comprise a subpopulation of CD2+ CD4- CD8- cells, reduced proliferation to L3 antigen extract only in one animal. The results suggest that either gammadelta T-cells could be involved in the proliferation or that another as yet unidentified population is important for proliferation. The precise role of these populations during infection with O. ostertagi and the mechanism by which these cells may influence the host immune response are important issues that remain to be elucidated.

Abomasum↗
PubMed2000

The F4 fimbrial antigen of Escherichia coli and its receptors.

F4 or K88 fimbriae are long filamentous polymeric surface proteins of enterotoxigenic Escherichia coli (ETEC), consisting of so-called major (FaeG) and minor (FaeF, FaeH, FaeC, and probably FaeI) subunits. Several serotypes of F4 have been described, namely F4ab, F4ac, and F4ad. The F4 fimbriae allow the microorganisms to adhere to F4-specific receptors present on brush borders of villous enterocytes and consequently to colonize the small intestine. Such ETEC infections are responsible for diarrhea and mortality in neonatal and recently weaned pigs. In this review emphasis is put on the morphology, genetic configuration, and biosynthesis of F4 fimbriae. Furthermore, the localization of the different a, b, c, and d epitopes, and the localization of the receptor binding site on the FaeG major subunit of F4 get ample attention. Subsequently, the F4-specific receptors are discussed. When the three variants of F4 (F4ab, F4ac, and F4ad) are considered, six porcine phenotypes can be distinguished with regard to the brush border adhesiveness: phenotype A binds all three variants, phenotype B binds F4ab and F4ac, phenotype C binds F4ab and F4ad, phenotype D binds F4ad, phenotype E binds none of the variants, and phenotype F binds F4ab. The following receptor model is described: receptor bcd is found in phenotype A pigs, receptor bc is found in phenotype A and B pigs, receptor d is found in phenotype C and D pigs, and receptor b is found in phenotype F pigs. Furthermore, the characterization of the different receptors is described in which the bcd receptor is proposed as collection of glycoproteins with molecular masses ranging from 45 to 70 kDa, the bc receptor as two glycoproteins with molecular masses of 210 an 240 kDa, respectively, the b receptor as a glycoprotein of 74 kDa, and the d receptor as a glycosphingolipid with unknown molecular mass. Finally, the importance of F4 fimbriae and their receptors in the study of mucosal immunity in pigs is discussed.

Animals↗
PubMed2000

Pharmacokinetic-pharmacodynamic analysis of the EEG effect of alfentanil in rats following beta-funaltrexamine-induced mu-opioid receptor "knockdown" in vivo.

PURPOSE: The objective of this investigation was to determine the influence of pre-treatment with the irreversible mu-opioid receptor antagonist beta-funaltrexamine (beta-FNA) on the pharmacokinetic-pharmacodynamic (PK/PD) relationship of alfentanil in rats. METHODS: The PK/PD correlation of alfentanil (2 mg x kg(-1) intravenously in 20 min) was determined in chronically instrumented rats using amplitudes in the 0.5-4.5 Hz frequency band of the EEG as pharmacodynamic endpoint. Beta-FNA was administered intravenously (10 mg x kg(-1)) either 35 min or 24 h prior to the PK/PD experiments. RESULTS: Pre-treatment with beta-FNA had no influence on the pharmacokinetics of alfentanil. The in vivo concentration-EEG effect relationships, however, were steeper and shifted towards higher concentrations with no difference between the 35-min and the 24-h pre-treatment groups. Analysis of the data on basis of the operational model agonism revealed that the observed changes could be explained by a 70-80% reduction in alfentanil efficacy in beta-FNA pre-treated rats. This is consistent with results from an in vitro receptor bioassay showing a 40-60% reduction in the number of specific mu-opioid binding sites in the brain. CONCLUSIONS: This investigation confirms the validity of a previously postulated mechanism-based PK/PD model for the effect of synthetic opiates in rats.

Alfentanil↗
PubMed1999

Seroprevalence of F4+ enterotoxigenic Escherichia coli in regions with different pig farm densities.

Sera of young sows from 135 closed Belgian pig breeding farms were examined for the presence of serum antibodies specific for the F4 fimbrial antigen of enterotoxigenic Escherichia coli (ETEC). Since 80% of all pig farms in Belgium are located in the provinces West-Vlaanderen (44%, approximately 18 farms/10 km2), Oost-Vlaanderen (20%, approximately 9 farms/10 km2), Antwerpen (10%, approximately 5 farms/10 km2) and Vlaams-Brabant (6%, approximately 3 farms/10 km2), the farms examined were randomly selected in these four regions. On 68% of all tested farms, sows were not vaccinated against enteric colibacillosis. In general, 65% of these non-vaccinated farms were F4-seropositive (mean optical density [OD405] >0.5) of which 38% were weakly (mean OD405 = 0.5-1.0), 21% moderately (mean OD405 = 1.0-2.0) and 6% strongly positive (mean OD405 > or =2.0). These percentages showed major differences between the four provinces. In Vlaams-Brabant, only 31% of non-vaccinated farms were seropositive, of which most were regarded as weakly positive. In Antwerpen, Oost- and West-Vlaanderen however, this percentage was clearly higher and respectively 68, 71, and 79% of non-vaccinated farms were seropositive, of which most were weakly positive. These observations indicate that F4+ ETEC is widely spread and highly prevalent on non-vaccinated pig breeding farms in Belgium. Moreover, an increasing F4-seropositivity with increasing pig farm density suggests a possible influence of the swine density on the prevalence of F4+ ETEC infections.

Animals↗
PubMed1999

Receptor-specific binding of purified F4 to isolated villi.

Different procedures for preparing and purifying F4ac fimbriae of the enterotoxigenic Escherichia coli strain GIS 26 (O149:K91:F4ac LT+Sta+STb+) were performed and the purity and yield of F4ac were compared. Fimbriae were prepared by either mechanical shearing or heatshock treatment of concentrated bacterial suspensions (10(11) bacteria/ml). The mechanical shearing procedure resulted in approximately 1.7 mg fimbriae (i.e. 74.4% of the isolated protein) and 0.6 mg (25.6%) contaminating proteins per 10(12) bacteria, whereas the yield of fimbriae following heatshock treatment was lower (0.3 mg per 10(12) bacteria, i.e. 26.2%) and the relative contamination higher (1.0 mg per 10(12) bacteria, i.e. 73.8%). A further purification consisted of either anion exchange chromatography (AEC) or electro-elution from SDS-polyacrylamide gels. The electroelution procedure was performed under reducing and denaturing conditions, so that purified FaeG subunits, the major subunit of F4, were finally obtained. The binding activity of fimbriae, nonpurified as well as purified, and FaeG to F4-specific receptors on isolated intestinal villi was assessed in an inhibition adhesion assay. Native fimbriae as well as major subunits were able to bind to the receptors, and the specificity of the binding was demonstrated by blockage with F4ac-specific MAb.

Animals↗
PubMed1999

Antigenicity of cortical bone allografts in dogs and effect of ethylene oxide-sterilization.

The aims of the present study were to determine the antigenicity of cortical bone allografts and the effect of ethylene oxide-sterilization (EO-sterilization). Cortical bone allografts from one donor dog were implanted in a muscle pouch in four groups of four dogs each. The grafts were either fresh, EO-sterilized, demineralized or demineralized and EO-sterilized. The immune response against the grafts was determined by measuring the antibody response against surface antigens of donor cells and by the mixed lymphocyte reaction. Dogs receiving EO-sterilized grafts or bone matrix did not demonstrate an immune response. Only two of the four dogs with fresh cortical bone grafts showed a very weak immune response. This suggests a priming of the host by the fresh bone grafts. However, implanting skin grafts from the donor dog subdermally, in one dog of each of the groups, four months after implanting the bone grafts did not induce a secondary immune response. Macroscopic and histologic examination of the bone grafts five months after their implantation consistently revealed graft resorption (activity of osteoclasts) and vascularization of the fresh bone grafts, but not of EO-sterilized fresh grafts. For most EO-sterilized grafts, a strong inflammatory reaction was present in the tissues surrounding the graft and this was not apparent around the non-sterilized grafts. The absence of resorption and the presence of the inflammation seemed to be unwanted effects of the EO-sterilization. The EO-sterilisation did not affect osteoinduction since osteocytes were observed in the EO-sterilized demineralized grafts. Results indicate that cortical bone allografts used in the present study are very weak antigens and that the EO-sterilization procedure used has no effect on osteoinduction, but decreases bone resorption.

Animals↗
PubMed1999

Protection of turkeys against Chlamydia psittaci challenge by gene gun-based DNA immunizations.

Particle-mediated (Helios Gene Gun) transfer to the turkey epidermis of plasmid DNA expressing the major outer membrane protein (MOMP) of an avian Chlamydia psittaci strain was evaluated for its ability to raise an immune response and protection against challenge with the homologous strain. In turkeys, the delivery of pcDNA1/MOMP coated onto 0.6 microm gold beads was the most efficient compared to immunisations using 1.0 or 1.6 microm gold beads. The delivery of as little as 1 microg pcDNA1/MOMP coated onto 0.6 microm gold beads was efficient. Immunisation with 1.0 microm gold beads required twice more (2 microg) DNA to achieve comparable results. The use of 2 microg DNA coated onto 1.6 microm gold beads had no effects. The gene gun delivery both primed T-helper and B-cell memory although recombinant MOMP-expressing cells did not induce high-titre antibody responses. The significance of gene gun-based DNA immunisation as a means of preventing severe clinical signs, lesions and chlamydia excretion in a turkey model of Chlamydia psittaci infection was demonstrated.

Animals↗
PubMed1999

Induction of immune responses in pigs following oral administration of purified F4 fimbriae.

An effective way of stimulating the mucosal immune system was examined in piglets, using F4 fimbriae of enterotoxigenic Escherichia coli (ETEC). It was demonstrated that purified F4 fimbriae, as opposed to ovalbumin (OVA), are powerful oral immunogens. Indeed, oral administration of purified F4 induced antigen-specific antibody-secreting cells (ASC) in the Peyer's patches, mesenteric lymph nodes (LN), blood and lamina propria 4, 7, 9 and 11 days postimmunization, respectively, indicating a stimulation of the mucosal immune system, whereas upon oral administration of OVA, no immune response was observed. Moreover, the induced F4-specific IgA and IgG antibody responses were comparable with those obtained upon oral infection with viable E. coli and intramuscular (i.m.) F4 injection, respectively. Furthermore, a priming of the mucosal immune system is better obtained by oral infection (ASC localized in mesenteric LN) than by i.m. F4 injection (ASC localized in spleen and retropharyngeal LN) since an oral boost with purified F4 induced a secondary response in the orally infected animal (mainly IgA and IgG ASC, rapid increase of IgA antibodies) while in the i.m. primed animal a secondary (more circulating antigen-specific ASC than in the unprimed animal) as well as a primary IgM and IgA response (mainly IgM ASC, slow increase of IgA antibodies), suggesting a primary mucosal response, were seen. An oral challenge of the naive control displayed a primary response (mainly IgM ASC, slow increase of IgA and IgG antibodies). The capacity of purified F4 to activate the mucosal immune system on oral administration, is of importance for the development of oral vaccines against ETEC infections.

Adhesins, Escherichia coli↗
PubMed1999

Turkeys are protected from infection with Chlamydia psittaci by plasmid DNA vaccination against the major outer membrane protein.

Plasmid DNA expressing the major outer membrane protein (MOMP) of an avian Chlamydia psittaci serovar A strain has been tested for its ability to raise an immune response and induce protection against challenge with the same serovar. A combined parenteral (intramuscular injection) and mucosal route (DNA drops administered to the nares) of DNA inoculation was compared with gene gun-based immunization. The gene gun delivery of pcDNA1/MOMP as well as the intramuscular-intranasal DNA delivery primed both T-helper and B cell memory, although rMOMP-expressing cells did not induce high antibody responses. Evidence for the priming of the memory was provided by the fact that the pcDNA1/MOMP inoculations raised antibodies belonging to the IgG and not IgM isotype. However, in response to challenge only five out of 15 vaccinated turkeys showed four-fold increases in serum IgG after challenge. By contrast, evidence for the priming of T cell memory in response to challenge was found in all vaccinated turkeys, as shown by the significantly heightened proliferative responses of peripheral blood lymphocytes following vaccination. Both immunization methods produced similar serological and lymphocyte proliferative responses. Notwithstanding the immunization method, a significant level of protection was observed in all pcDNA1/MOMP-immunized turkeys. The efficacy of MOMP-based DNA vaccination as a means of preventing severe clinical signs, lesions and chlamydia excretion in a turkey model of C. psittaci infection was demonstrated.

Animals↗
PubMed1999

Receptor-dependent immune responses in pigs after oral immunization with F4 fimbriae.

F4 receptor-positive (F4R+) and F4 receptor-negative (F4R-) pigs were orally vaccinated with purified F4 fimbriae of enterotoxigenic Escherichia coli (ETEC). Serum immunoglobulin G (IgG) and IgA responses were readily detected in F4R+ animals, whereas immune responses were not detected in F4R- animals. Even after a subsequent oral infection with virulent F4(+) ETEC and a booster immunization with F4, the F4R- animals remained F4 seronegative whereas the unvaccinated F4R+ pigs exhibited clear IgA and IgG responses. These results clearly demonstrate that F4Rs are a prerequisite for an immune response following oral immunization. Furthermore, indications that oral F4 vaccination can induce mucosal protection were obtained, since the experimental ETEC infection did not induce a systemic booster response or fecal ETEC excretion in orally vaccinated F4R+ pigs, in contrast to the clear immune response and ETEC excretion of unvaccinated F4R+ animals. F4-specific IgA antibodies could be found in the feces of the vaccinated F4R+ pigs. They are secreted at the intestinal mucosal surface and appear to prevent ETEC infection. The F4R-dependent induction of a mucosal immune response can be used as a model to better understand mucosal immunization and mucosal immune responses and can contribute to the development of oral vaccines in veterinary as well as in human medicine.

Adhesins, Escherichia coli↗
PubMed1999

Population pharmacokinetics of lamotrigine adjunctive therapy in adults with epilepsy.

Plasma concentrations of lamotrigine, an antiepileptic drug obtained in three adult controlled clinical trials conducted in the United States were pooled and analyzed using NONMEM, a population pharmacokinetic computer program, to facilitate development of dosing guidelines. A total of 2,407 lamotrigine plasma concentrations from 527 patients with epilepsy were analyzed. Regression equations for oral clearance were developed as a function of body size, age (18-64 years), gender, race, and use of concomitant antiepileptic drugs. The population mean apparent oral clearance of lamotrigine in adult patients receiving one concomitant enzyme-inducing antiepileptic drug and not valproic acid was estimated to be 1 mL/min/kg. Gender and age did not affect clearance significantly. On average, clearance was reduced by 25% in non-whites and increased by 13% in patients receiving more than one concomitant enzyme-inducing antiepileptic agent. Lamotrigine did not influence the disposition of phenytoin or carbamazepine. Dosing adjustments for lamotrigine in patients receiving concomitant enzyme-inducing antiepileptic drugs and not valproic acid should not be necessary for age, gender, or the number of concomitant enzyme-inducing antiepileptic drugs. Lamotrigine does not influence the dosing requirements for phenytoin or carbamazepine.

Adolescent↗
PubMed1998

Varicella-zoster virus ORF57, unlike its pseudorabies virus UL3.5 homolog, is dispensable for viral replication in cell culture.

Varicella zoster virus (VZV) encodes five genes that do not have homologs in herpes simplex virus. One of these genes, VZV ORF57, is predicted to encode a protein containing 71 amino acids. Antibody to ORF57 protein immunoprecipitated a 6-kDa protein in the cytosol of VZV-infected cells. Although the homolog of VZV ORF57 in pseudorabies virus, UL3.5, is critical for viral egress and growth in cell culture, VZV unable to express ORF57 replicated to titers similar to those seen with parental virus. Thus VZV ORF57 has a different role in viral replication than its pseudorabies virus homolog.

Cytosol↗
PubMed1998

Identification of an inhibin receptor in gonadal tumors from inhibin alpha-subunit knockout mice.

Inhibins and activins are dimeric proteins that are functional antagonists and are structurally related to the transforming growth factor-beta (TGFbeta) family of growth and differentiation factors. Receptors for activin and TGFbeta have been identified as dimers of serine-threonine kinase subunits that regulate cytoplasmic proteins known as Smads. Despite major advances in our understanding of activin and TGFbeta receptors and signaling pathways, little is known about inhibin receptors or the mechanism by which this molecule provides a functionally antagonistic signal to activin. Studies described in this paper indicate that an independent inhibin receptor exists. Numerous tissues were examined for inhibin-specific binding sites, including the developing embryo, in which the spinal ganglion and trigeminal ganglion-bound iodinated inhibin A. Sex cord stromal tumors, derived from male and female inhibin alpha-subunit-deficient mice, were also identified as a source of inhibin receptor. Abundant inhibin and few activin binding sites were identified in tumor tissue sections by in situ ligand binding using iodinated recombinant human inhibin A and 125I-labeled recombinant human inhibin A. Tumor cell binding was specific for each ligand (competed by excess unlabeled homologous ligand and not competed by heterologous ligand). Based on these results and the relative abundance and homogeneity of tumor tissues versus the embryonic ganglion, tumor tissues were homogenized, membrane proteins were purified, and putative inhibin receptors were isolated using an inhibin affinity column. Four proteins were eluted from the column that bind iodinated inhibin but not iodinated activin. These data suggest that inhibin-specific membrane-associated proteins (receptors) exist.

Activin Receptors↗
PubMed1998

High-level expression of Chlamydia psittaci major outer membrane protein in COS cells and in skeletal muscles of turkeys.

The omp1 genes encoding the major outer membrane proteins (MOMPs) of avian Chlamydia psittaci serovar A and D strains were cloned and sequenced. The nucleotide sequences of the avian C. psittaci serovar A and D MOMP genes were found to be 98.9 and 87.8% identical, respectively, to that of the avian C. psittaci serovar A strain 6BC, 84.6 and 99.8% identical to that of the avian C. psittaci serovar D strain NJ1, 79.1 and 81.1% identical to that of the C. psittaci guinea pig inclusion conjunctivitis strain, 60.9 and 62.5% identical to that of the Chlamydia trachomatis L2 strain, and 57.5 and 60.4% identical to that of the Chlamydia pneumoniae IOL-207 strain. The serovar A or D MOMPs were cloned in the mammalian expression plasmid pcDNA1. When pcDNA1/MOMP A or pcDNA1/MOMP D was introduced into COS7 cells, a 40-kDa protein that was identical in size, antigenicity, and electrophoretic mobility to native MOMP was produced. Recombinant MOMP (rMOMP) was located in the cytoplasm of transfected COS7 cells as well as in the plasma membrane and was immunoaccessible. Intramuscular administration of pcDNA1/MOMP in specific-pathogen-free turkeys resulted in local expression of rMOMP in its native conformation, after which anti-MOMP antibodies appeared in the serum.

Amino Acid Sequence↗
PubMed1998

Varicella-zoster virus (VZV) ORF32 encodes a phosphoprotein that is posttranslationally modified by the VZV ORF47 protein kinase.

Varicella-zoster virus (VZV) encodes five gene products that do not have homologs in herpes simplex virus. One of these genes, VZV open reading frame 32 (ORF32), is predicted to encode a protein of 16 kDa. VZV ORF32 protein was shown to be phosphorylated and located in the cytosol of virus-infected cells. Antibody to ORF32 protein immunoprecipitated 16- and 18-kDa phosphoproteins from VZV-infected cells. Since VZV encodes two protein kinases that might phosphorylate ORF32 protein, immunoprecipitations were performed with cells infected with VZV mutants unable to express either of the viral protein kinases. Cells infected with VZV unable to express the ORF66 protein kinase contained both the 16- and 18-kDa ORF32 phosphoproteins; however, cells infected with the VZV ORF47 protein kinase mutant showed only the 16-kDa ORF32 phosphoprotein. Treatment of [35S]methionine-labeled proteins with calf intestine alkaline phosphatase resulted in a decrease in size of the ORF32 proteins from 16 and 18 kDa to 15 and 17 kDa, respectively. VZV unable to express ORF32 protein replicated in human melanoma cells to titers similar to those seen with parental virus; however, VZV unable to express ORF32 was impaired for replication in U20S osteosarcoma cells. Thus, VZV ORF32 protein is posttranslationally modified by the ORF47 protein kinase. Since the VZV ORF47 protein kinase has recently been shown to be critical for replication in human fetal skin and lymphocytes, its ability to modify the ORF32 protein suggests that the latter protein may have a role for VZV replication in human tissues.

Base Sequence↗
PubMed1997

The health care cost of drug-related morbidity and mortality in nursing facilities.

BACKGROUND: Preventable drug-related morbidity and mortality within nursing facilities represent a serious problem urgently requiring expert medical attention. The health care costs of drug-related problems can be both immense and avoidable. However, the research to date has been narrow in scope, focusing on the drug costs avoided and failing to consider the wider range of possible negative outcomes and potential drug-related problems. OBJECTIVES: To develop a model of therapeutic outcomes resulting from drug therapy within nursing facilities, to estimate the magnitude of the cost of drug-related morbidity and mortality within nursing facilities in the United States, and to assess the impact of pharmacist-conducted, federally mandated, monthly, retrospective review of nursing facility residents' drug regimens in reducing the cost of drug-related morbidity and mortality. METHODS: Using decision analysis techniques, a probability pathway model was developed to estimate the cost of drug-related problems within nursing facilities. An expert panel consisting of consultant pharmacists and physicians with practice experience in nursing facilities and geriatric care was surveyed to determine conditional probabilities of therapeutic outcomes attributable to drug therapy. Health care utilization and associated costs derived from negative therapeutic outcomes were estimated. RESULTS: Baseline estimates indicate that the cost of drug-related morbidity and mortality with the services of consultant pharmacists was $4 billion compared with $7.6 billion without the services of consultant pharmacists. CONCLUSIONS: Drug-related morbidity and mortality in nursing facilities represent a serious economic problem. For every dollar spent on drugs in nursing facilities, $1.33 in health care resources are consumed in the treatment of drug-related problems. With the current federally mandated drug regimen review, it is estimated that consultant pharmacists help to reduce health care resources attributed to drug-related problems in nursing facilities by $3.6 million.

Cost of Illness↗
PubMed1997

Expression of beta 2 integrins on blood leukocytes of cows with or without bovine leukocyte adhesion deficiency.

Peripheral blood leukocytes of 11 normal cows, 7 cows heterozygous and 2 heifers homozygous for bovine leukocyte adhesion deficiency (BLAD) were analysed by flow cytometry for the intensity of their beta 2 integrin expression (LFA-1(CD11a/CD18), CR3 (CD11b/CD18) and CR4 (CD11c/CD18)). BLAD-homozygotes revealed no or a very weak expression of the beta 2 integrins and had a 10-fold and 4- to 5-fold increase in absolute number of neutrophils and monocytes, respectively, whereas the absolute number of lymphocytes remained normal. The mean fluorescence intensity (MFI) of the beta 2 integrins (CD18) in heterozygous animals was 56 to 90% of this in the normal cows (MFI between 14 and 512). The difference in the expression level was most pronounced for LFA-1 on the small cluster of lymphocytes with the highest MFI for LFA-1. Repeated analysis and phorbol myristate acetate stimulation revealed that the LFA-1 expression on this high-expressing cell population of the peripheral blood allowed a ready identification of BLAD-heterozygotes by flow cytometry.

Animals↗