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Biomedical subjects

K J Yoon

Publications and source records attributed to K J Yoon.

At least 19 recordsLinked to original sources
PubMed2006

Optimization of a sampling system for recovery and detection of airborne porcine reproductive and respiratory syndrome virus and swine influenza virus.

The objective of this research was to optimize sampling parameters for increased recovery and detection of airborne porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus (SIV). Collection media containing antifoams, activated carbons, protectants, and ethylene glycol were evaluated for direct effects on factors impacting the detection of PRRSV and SIV, including virus infectivity, viability of continuous cell lines used for the isolation of these viruses, and performance of reverse transcriptase PCR assays. The results showed that specific compounds influenced the likelihood of detecting PRRSV and SIV in collection medium. A subsequent study evaluated the effects of collection medium, impinger model, and sampling time on the recovery of aerosolized PRRSV using a method for making direct comparisons of up to six treatments simultaneously. The results demonstrated that various components in air-sampling systems, including collection medium, impinger model, and sampling time, independently influenced the recovery and detection of PRRSV and/or SIV. Interestingly, it was demonstrated that a 20% solution of ethylene glycol collected the greatest quantity of aerosolized PRRSV, which suggests the possibility of sampling at temperatures below freezing. Based on the results of these experiments, it is recommended that air-sampling systems be optimized for the target pathogen(s) and that recovery/detection results should be interpreted in the context of the actual performance of the system.

Air Microbiology↗
PubMed2005

The exercise-induced enhancement of influenza immunity is mediated in part by improvements in psychosocial factors in older adults.

The primary goal of this study was to determine whether exercise-associated improvements of the immune response to influenza vaccination were mediated by improvements in psychosocial factors in older adults. At baseline, prior to the exercise intervention, older adult participants were immunized with influenza vaccine. Blood samples collected pre-immunization, 1, 4, and 12 weeks post-immunization were analyzed for anti-influenza antibody, whereas influenza-specific cytokine (IFNgamma) was evaluated at 1 week post-immunization. Depression and sense of coherence were measured pre-immunization. Four weeks post-immunization, participants were randomly assigned to either an aerobic exercise group (n=14) or a control group (n=14). After a 10-month exercise intervention, the immunization, blood collections, and psychosocial measures were repeated. At the post-intervention evaluation, exercise participants had improved scores on depression and sense of coherence. Also post-intervention, exercise participants had a greater increase in antibody and IFNgamma production. After controlling for the effect of both psychosocial measures, the exercise treatment remained significant with respect to antibody titer suggesting that the increases in antibody were not mediated by improvement in the psychosocial factors. In contrast, the enhancement of IFNgamma appeared to be mediated at least in part by the psychosocial factors. After controlling for psychosocial factors, exercise treatment was no longer significantly related to the change in IFNgamma. Taken together, our findings may suggest that the mechanism(s) of exercise-induced improvement in immunocompetence involve both physiological and psychological pathways.

Affect↗
PubMed2002

Porcine circovirus type 2 (PCV-2) coinfections in US field cases of postweaning multisystemic wasting syndrome (PMWS).

The prevalence of different pathogens detected in combination with porcine circovirus type 2 (PCV-2) was studied retrospectively in field cases of postweaning multisystemic wasting syndrome (PMWS) diagnosed at the Iowa State University Veterinary Diagnostic Laboratory, Ames, Iowa, between January 2000, and September 2001. The presence of PCV-2 antigen in lymphoid tissues and/or lung, demonstrated by immunohistochemistry, together with moderate to severe lymphoid depletion and/or granulomatous lymphadenitis, was used as the criteria for the diagnosis of PMWS. A total of 484 cases fulfilled these criteria. Most of the cases (294/369) of PMWS occurred in pigs between the ages of 8 and 18 weeks, with a peak at 10 weeks of age. Porcine reproductive and respiratory syndrome virus was detected in 51.9% of the cases, Mycoplasma hyopneumoniae in 35.5%, bacterial septicemia in 14.0%, bacterial pneumonia in 7.6%, swine influenza virus in 5.4%, and PCV-2 alone in 1.9%. In cases with bacterial septicemia the most frequently isolated pathogen was Streptococcus suis. In cases with bacterial pneumonia, Pasteurella multocida was the most prevalent.

Animals↗
PubMed2001

Emerging erythromycin resistance among group B streptococci in Korea.

In order to determine possible trends in the susceptibility and distribution of group B streptococci (GBS) serotypes in a Korean population and to elucidate any relationship between the serotypes and the antimicrobial susceptibility patterns found, 185 clinical isolates of GBS were investigated between 1990 and 1998. The rate of erythromycin resistance increased from 0% during the period 1990-1995 to 26% in 1996 and 40% in 1998. The overall rates of resistance to erythromycin and clindamycin were 20% and 22.2%, respectively. GBS serotype V was not detected until 1995, but it was isolated in 1996 and ranked third in frequency (18.8%) in 1997. Among the 37 erythromycin-resistant strains detected, 54.1% and 29.7% were of serotype III and V, respectively. The emerging erythromycin resistance detected among these GBS isolates was mainly due to a sudden increase in the incidence of GBS serotypes with multidrug-resistant phenotypes.

Anti-Bacterial Agents↗
PubMed2001

Structure and function of a vimentin-associated matrix adhesion in endothelial cells.

The alpha4 laminin subunit is a component of endothelial cell basement membranes. An antibody (2A3) against the alpha4 laminin G domain stains focal contact-like structures in transformed and primary microvascular endothelial cells (TrHBMECs and HMVECs, respectively), provided the latter cells are activated with growth factors. The 2A3 antibody staining colocalizes with that generated by alphav and beta3 integrin antibodies and, consistent with this localization, TrHBMECs and HMVECs adhere to the alpha4 laminin subunit G domain in an alphavbeta3-integrin-dependent manner. The alphavbeta3 integrin/2A3 antibody positively stained focal contacts are recognized by vinculin antibodies as well as by antibodies against plectin. Unusually, vimentin intermediate filaments, in addition to microfilament bundles, interact with many of the alphavbeta3 integrin-positive focal contacts. We have investigated the function of alpha4-laminin and alphavbeta3-integrin, which are at the core of these focal contacts, in cultured endothelial cells. Antibodies against these proteins inhibit branching morphogenesis of TrHBMECs and HMVECs in vitro, as well as their ability to repopulate in vitro wounds. Thus, we have characterized an endothelial cell matrix adhesion, which shows complex cytoskeletal interactions and whose assembly is regulated by growth factors. Our data indicate that this adhesion structure may play a role in angiogenesis.

Antibodies, Monoclonal↗
PubMed2001

Antigenic importance of the carboxy-terminal beta-strand of the porcine reproductive and respiratory syndrome virus nucleocapsid protein.

Five domains of antigenic importance were previously mapped on the nucleocapsid protein (N) of the porcine reproductive and respiratory syndrome virus (PRRSV), and a domain comprised of the 11 C-terminal-most amino acids (residues 112 to 123) was shown to be essential for binding of N-specific conformation-dependent monoclonal antibodies (MAbs). In the present study, the importance of individual residues within this C-terminal domain for antigenicity was investigated using eight different mutant constructs of N expressed in HeLa cells. Single amino acid substitutions were introduced into the C-terminal domain of the N protein, and the significance of individual amino acids for MAb reactivity was determined by immunoprecipitation. None of the MAbs tested recognized the mutant with a leucine-to-proline substitution at residue 114 (L114P), while V112P, R113P, R113D, I115P, and R116P reduced MAb binding significantly. Conversely, substitution of amino acids at positions 118 (T118S) and 121 (P121A) had little effect on MAb binding. Secondary-structure predictions indicate that amino acids 111 to 117 form a beta-strand. In view of the fact that replacement of beta-strand-forming amino acids with proline elicited the greatest effect on MAb binding, it appears that secondary structure in the C terminus of the N protein is an important determinant of conformational epitope formation. While the crystal structure of the PRRSV N protein remains to be determined, results from these studies broaden our understanding of the secondary structures that make up the PRRSV N protein and shed some light on how they may relate to function.

Amino Acid Sequence↗
PubMed2001

Shedding of porcine reproductive and respiratory syndrome virus in mammary gland secretions of sows.

OBJECTIVE: To document shedding of porcine reproductive and respiratory syndrome (PRRS) virus in mammary gland secretions of experimentally inoculated sows, to evaluate effects of vaccination during gestation on virus shedding during the subsequent lactation, and to evaluate shedding of PRRS virus in milk of sows in commercial herds. ANIMALS: 6 sows seronegative for PRRS virus were used for experiment 1, and 2 sows were retained for experiment 2. For experiment 3, 202 sows in commercial herds were used. PROCEDURE: In experiment 1, 2 sows were inoculated with PRRS virus, 2 sows were vaccinated with modified-live PRRS virus vaccine, and 2 sows served as control pigs. Mammary gland secretions were assayed for PRRS virus. In experiment 2, pregnant vaccinated sows from experiment 1 were vaccinated with another modified-live PRRS virus vaccine. Mammary gland secretions were assayed in the same manner as for experiment 1. For experiment 3, milk collected from 202 sows in commercial herds was assayed for PRRS virus. RESULTS: In experiment 1, PRRS virus was detected in mammary gland secretions of both vaccinated and 1 of 2 virus-inoculated sows. In experiment 2, virus was not detected in samples from either vaccinated sow. In experiment 3, all samples yielded negative results. CONCLUSIONS AND CLINICAL RELEVANCE: Naïve sows inoculated late in gestation shed PRRS virus in mammary secretions. Previous vaccination appeared to prevent shedding during the subsequent lactation. Results for samples obtained from sows in commercial herds suggested that virus shedding in mammary gland secretions of such sows is uncommon.

Animals↗
PubMed2001

Carcinoma originating from aberrant breast tissue of the right upper anterior chest wall : a case report.

Aberrant breast tissue is usually found in proximity to the normal breast, that is, in the axillary, sternal or clavicular regions. Carcinoma occurs more frequently in the aberrant tissue of the axilla than the extra-axillary site though the overall incidence of tumors of aberrant breast tissue is low. To our knowledge, studies regarding the carcinoma of aberrant breast tissue of the extra-axillary site have been reported rarely. Here we report a recent case of carcinoma originating from the extra-axillary aberrant breast tissue, presenting as a subcutaneous nodule on the right upper anterior chest wall. It is suggested that subcutaneous nodules of uncertain origin around the periphery of the breast should be suspected for breast carcinoma as a differential diagnosis and treated properly.

Breast Neoplasms↗
PubMed2000

Detection and isolation of coronavirus from feces of three herds of feedlot cattle during outbreaks of winter dysentery-like disease.

Clinical signs of a winter dysentery-like syndrome in 6- to 9-month-old cattle in 3 feedlots included acute onset of diarrhea with high morbidity and low mortality, respiratory tract problems that included dyspnea, coughing, and nasal discharge, and high rectal temperatures. Bovine coronavirus was detected by use of an ELISA and immune electron microscopy in fecal and nasal swab samples and by immunohistochemical analysis of intestinal sections collected from calves during necropsy. Bovine coronavirus should be considered in the differential diagnoses for diseases that cause acute onset of bloody diarrhea in feedlot cattle.

Animals↗
PubMed2000

Emergence of H3N2 reassortant influenza A viruses in North American pigs.

In late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of North Carolina, Texas, Minnesota and Iowa. Four viral isolates from outbreaks in different states were analyzed, both antigenically and genetically. All of the isolates were identified as H3N2 influenza viruses with antigenic profiles similar to those of recent human H3 strains. Genotyping and phylogenetic analysis demonstrated that the four swine viruses had emerged through two different pathways. The North Carolina isolate is the product of genetic reassortment between human and swine influenza viruses, while the others arose from reassortment of human, swine and avian viral genes. The hemagglutinin genes of the four isolates were all derived from the human H3N2 virus circulating in 1995. It remains to be determined if either of these recently emerged viruses will become established in the pigs in North America and whether they will become an economic burden.

Animals↗
PubMed2000

Categorization of North American porcine reproductive and respiratory syndrome viruses: epitopic profiles of the N, M, GP5 and GP3 proteins and susceptibility to neutralization.

Eleven epitopes were identified by murine monoclonal antibodies (MAbs) that represented the N, M, GP5 and GP3 proteins of the North American (NA) porcine reproductive and respiratory syndrome (PRRS) virus, KY 35 (NVSL 46907). Three discontinuous epitopes of the N and M proteins were designated EpORF7-Fd through Hd and EpORF6-Ad through Cd. Five continuous epitopes of the GP5 and GP3 proteins were designated EpORF5-A through C and EpORF3-A and B. The MAbs representing EpORF5-C and EpORF6-A and B had neutralizing activity. The MAbs representing the above epitopes, except EpORF7-Gd and Hd, expanded the virus marker system described in a previous study in which a panel of 69 NA viruses and the Lelystad virus were categorized into 5 antigenic groups, I15 through V15 based on the presence or absence of 5 continuous epitopes of the N protein. Antigenic groups I15 and II15, which represented 84.7 and 11.6% of all viruses tested, were categorized further into 9 and 4 subgroups, respectively. The remaining NA viruses and the Lelystad virus were distributed among 4 groups, one of which was represented by 2 subgroups. Significant (P<0.05) differences in sensitivity to neutralization of 28 viruses representing 6 antigenic groups by the 3 neutralizing MAbs suggested that sensitivity to neutralization may also be of value in categorizing PRRS viruses.

Animals↗
PubMed2000

Synergism between porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis in swine.

Porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis are two leading causes of economic loss in the swine industry. While respiratory disease is common in both S. choleraesuis and PRRSV infections, the factors that contribute to its development remain largely undefined. We investigated the interaction of PRRSV, S. choleraesuis, and stress in 5-week-old swine. All combinations of three factors (inoculation with S. choleraesuis on Day 0, PRRSV on Day 3, and treatment with dexamethasone on Days 3-7) were used to produce eight treatment groups in two independent trials. Fecal samples, tonsil and nasal swabs, serum samples and postmortem tissues were collected for bacteriologic and virologic examinations. No clinical signs were observed in pigs inoculated with only PRRSV or only S. choleraesuis. In contrast, pigs which were dually infected with S. choleraesuis and PRRSV exhibited unthriftiness, rough hair coats, dyspnea, and diarrhea. The pigs which received all three treatment factors were the most severely affected and 43% (three of seven) of the animals in this group died. Individuals in this group shed significantly higher quantities of S. choleraesuis in feces and had significantly higher serum PRRSV titers compared to other treatments (p < or = 0.05). In addition, S. choleraesuis and PRRSV were shed longer and by more pigs in this group than other groups and S. choleraesuis was recovered from more tissues in this group on Day 21 post inoculation. These results suggested that PRRSV, S. choleraesuis, and dexamethasone acted synergistically to produce a syndrome similar to that observed in the field.

Animals↗
PubMed2000

Immune components in porcine mammary secretions.

Immune components present in mammary secretions are reviewed. In swine, the histological structure of the placenta prevents in utero transfer of immunoglobulins and mammary secretions are the sole source of maternal antibody for the neonate. In addition to immunoglobulins, porcine mammary secretions contain significant numbers of maternal cells of various types that may contribute to neonatal immunity, including phagocytes (neutrophils and macrophages), lymphocytes (B and T cells), and epithelial cells. Immunomodulating and/or antimicrobial substances, including lactoferrin, lysozyme, lactoperoxidase, and cytokines, are also present in mammary secretions and may contribute to the protection of the neonate. While the role of immunoglobulins in mammary secretions is well understood, the contribution of cellular components and non-specific immune factors to neonatal immunity remains to be defined.

Animals↗
PubMed2000

Characterization of immune response of young pigs to porcine circovirus type 2 infection.

A longitudinal study was conducted to characterize the immune response of young swine to infection with porcine circovirus type 2 (PCV-2). Five 8-week-old cesarean-derived, colostrum-deprived pigs were inoculated intranasally and intramuscularly with a field isolate of PCV-2 at a concentration of 10(4) TCID50/mL. Along with monitoring for clinical signs and viremia, serum samples were collected from all pigs at day 0 and thereafter every 7 days postinoculation (PI) until the termination of the study on day 35 PI. No clinical signs were observed in any of the animals during the study period. In all pigs, PCV-2 was detected by polymerase chain reaction (PCR) in serum samples collected on days 7, 14, and 21 PI. Viral DNA and antigens were detected by in situ hybridization and immunohistochemistry in tonsil, spleen, medial iliac lymph nodes, and ileum collected from each pig at the end of the study. Collectively, naïve young swine were shown to be susceptible to PCV-2. Virus-specific antibody was detected by an indirect fluorescent antibody (IFA) assay on day 14 PI, but virus-neutralizing antibody was not detected until day 28 PI. As neutralizing antibodies developed, cross-reactivity with PCV type 1 (PCV-1) also developed on the IFA test. Western immunoblot analysis revealed three PCV-2 proteins with molecular masses of 28 kd, 28.5 kd, and 35 kd. The 35-kd protein was also demonstrated in PCV-1, suggesting that this protein induced the cross-reactivity between PCV types 1 and 2. Antibody to the 28-kd protein was detected on day 14 PI and later, indicating that this protein was the most immunogenic. Because of its immunogenicity and specificity to PCV-2, and 28-kd protein might provide the antigenic basis for the development of diagnostic tests for detection of PCV-2 antibody.

Animals↗