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Biomedical subjects

E A Nelson

Publications and source records attributed to E A Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1995

Antigenic differences between European and American isolates of porcine reproductive and respiratory syndrome virus (PRRSV) are encoded by the carboxyterminal portion of viral open reading frame 3.

Antigenic differences between European and American isolates of porcine reproductive and respiratory syndrome virus (PRRSV) were revealed by serologic analysis of a recombinant protein derived from PRRSV open reading frame 3 (ORF 3). The hydrophilic carboxyterminal 199 amino acids encoded by the ORF 3 of a European (Lelystad) isolate of PRRSV were expressed as a recombinant fusion protein (BP03-P) in a baculovirus gene expression system. Sera from gnotobiotic swine exposed to prototypic reference European and American isolates of PRRSV and sera from conventionally reared European and American swine convalescing from naturally acquired PRRSV infections were used to characterize the BP03-P protein. Sera from gnotobiotic and conventionally reared swine exposed to European isolates of PRRSV were significantly more reactive (P < 0.01) with BP03-P than were the corresponding American PRRSV antisera using the indirect immunoperoxidase monolayer assay (IPMA). Prototypic European, but not American, PRRSV antisera also recognized BP03-P using western immunoblotting and radioimmunoprecipitation assay (RIPA) procedures. However, gnotobiotically derived antiserum to an atypical American-origin PRRSV was reactive with BP03-P by both IPMA and western immunoblot. Despite a predicted potential for N-linked glycosylation, studies with tunicamycin and peptide-N-glycosidase F (PNGase F) indicated that BP03-P was not N-glycosylated in either insect cell cultures or Trichoplusia ni larvae infected with the recombinant baculovirus. Sera from rabbits inoculated with BP03-P failed to neutralize both the European (Lelystad) and American (ATCC VR-2332) reference isolates of PRRSV and did not react by IPMA with PRRSV-infected cell cultures. Taken together, the data suggest that the carboxyterminal portion of PRRSV ORF 3 encodes a non-neutralizing viral peptide that is partially responsible for the serologic differences noted between European and most American isolates of PRRSV.

Animals↗
PubMed1995

Isolated congenital tuberculosis otitis in a preterm infant.

We report an unusual case of localized congenital tuberculosis otitis in a preterm infant. Unlike disseminated congenital cases, the manifestations of localized otitis are associated with a triad of signs: (i) regional lymphadenopathy in the absence of typical systemic features of tuberculosis; (ii) delayed onset of presentation; and (iii) refractory otitis unresponsive to conventional antimicrobial agents. The need for greater diligence in looking for neonatal tuberculosis is emphasized, especially in an ethnic or socioeconomic environment where the disease is prevalent.

Antibiotics, Antitubercular↗
PubMed1995

Detection of porcine reproductive and respiratory syndrome virus in boar semen by PCR.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes a devastating disease in swine. The presence and transmission of PRRSV by boar semen has been demonstrated by using a swine bioassay. In this assay, 4- to 8-week-old pigs were inoculated intraperitoneally with semen from PRRSV-infected boars. Seroconversion of these piglets indicated the presence of PRRSV in semen. Seroconversion in gilts has also been demonstrated following artificial insemination with semen from PRRSV-infected boars. These methods of detecting PRRSV in boar semen are time-consuming, laborious, and expensive. The objective of this study was to develop a reliable and sensitive PCR assay to directly detect PRRSV in boar semen. Primers from open reading frames 1b and 7 of the PRRSV genome were used in nested PCRs. Virus was detected at concentrations as low as 10 infectious virions per ml in PRRSV-spiked semen. Specificity was confirmed by using a nested PCR and a 32P-labeled oligonucleotide probe. The primers did not react with related arteriviruses or other swine viruses. The PCR assay showed good correlation with the swine bioassay, and both methods were superior to virus isolation. To consistently identify PRRSV in boar semen, the cell fraction was separated by centrifugation at 600 x g for 20 min, a lysis buffer without a reducing agent (2-mercaptoethanol) was used, and nondiluted and 1:20-diluted cell fractions were evaluated by PCR. PRRSV was not reliably detected in the seminal plasma fraction of boar semen.

Animals↗
PubMed1995

Pathogenesis of porcine reproductive and respiratory syndrome virus infection in gnotobiotic pigs.

The pathogenesis of porcine reproductive and respiratory syndrome virus (PRRSV) was determined in gnotobiotic pigs by studying the sequential development of microscopic lesions and sites of virus distribution and replication. Thirty-two pigs (three pigs/infected group and one pig/control group) were inoculated by nasal instillation of either PRRSV isolate ATCC VR-2332 (total dose 10(2.6) TCID50) or uninfected cell culture supernatant. Infected and control pigs were euthanized at 12 hours, and 1, 2, 3, 5, 7, 14, and 21 days postexposure (PE). Gnotobiotic pigs experimentally infected with PRRSV were viremic by 12 hours PE and subsequently developed pneumonia, lymphadenopathy, vasculitis, myocarditis and encephalitis. Lung lesions developed by day 3 PE, persisted through day 21 PE and were characterized by alveolar septa thickened by macrophages, alveolar proteinaceous and karyorrhectic debris, alveolar syncytial cells, and multifocal type II pneumocyte hypertrophy. Lymph node lesions varied in distribution and severity and were characterized by germinal center hypertrophy and hyperplasia, lymphocyte necrosis, multiple cystic spaces, and polykaryocytes within the cystic spaces. Heart lesions were a late feature of infection and all infected pigs had heart lesions on day 21 PE characterized by subendocardial, myocardial, and perivascular foci of lymphocytes. Vasculitis also varied in distribution and severity and affected all sizes of vessels. Results of this experiment indicate that PRRSV is a multisystem disease characterized initially by viremia with subsequent virus distribution and replication in multiple organs causing interstitial pneumonia, vasculitis, lymphadenopathy, myocarditis, and encephalitis.

Animals↗
PubMed1995

Persistence of porcine reproductive and respiratory syndrome virus in serum and semen of adult boars.

Four seronegative adult boars were intranasally inoculated with porcine reproductive and respiratory syndrome virus (PRRSV) isolate VR-2332. Serum and semen were collected 2-3 times weekly for over 100 days postinoculation (DPI). Serum samples were assayed for PRRSV by virus isolation (VI) and a polymerase chain reaction (PCR) and screened for antibodies to PRRSV using the indirect fluorescent antibody (IFA) and virus neutralization (VN) tests. Semen was assayed for PRRSV RNA by PCR. Virus and viral RNA was detected in the serum of all boars within 1 DPI by Vi and/or PCR. However, VI results indicated that viremia was transient and occurred from 1 to 9 DPI. Viral RNA was detected in serum from 1 to 31 DPI. In the acute stage of the infection, PRRSV RNA was detected in serum by PCR prior to the presence of viral RNA in semen. The PRRSV RNA was detected in semen as early as 3 DPI and persisted for 25 DPI in 2 of the boars and 56 and 92 DPI in the remaining 2 boars. Detection of PRRSV RNA in semen occurred 2-8 and 28-35 days prior to the detection of antibodies by IFA and VN, respectively. PRRSV was isolated from the bulbourethral gland of the boar that shed viral RNA in semen for 92 DPI. These results suggest that PRRSV RNA can be detected by PCR in boar serum and semen, and may persist for variable periods of time. Viremia and the serologic status of the boar are not adequate indicators of when PRRSV or PRRSV RNA is being shed in the semen. Preliminary findings also indicated that neither shipping stress nor reinoculation with homologous PRRSV resulted in viremia or viral RNA shedding in semen.

Animals↗
PubMed1995

Improvements in bandaging technique following training.

Effective compression bandaging is critical for leg ulcer care. The bandaging technique of 18 nurses was assessed using a pressure monitor and the assessment repeated after training with feedback from the monitor. The use of a bandage marked with a tension indicator resulted in a small, insignificant improvement in bandaging technique. The combination of training and feedback significantly improved the nurses' bandaging technique. This improvement was sustained on retesting two weeks later.

Bandages↗
PubMed1995

The management of leg ulcers in a patient with ulcerative colitis. This case study details the treatment of a patient with pyoderma gangrenosum on the shins of both legs.

Pyoderma gangrenosum is a rare condition which is sometimes associated with ulcerative colitis and Crohn's disease. The pathological basis is not completely understood but it may be caused by vasculitis. The lesions are typically said to have purple overhanging edges and a necrotic base. The condition may also occur with rheumatoid arthritis, multiple myeloma and leukaemia. The treatment of choice is systemic steroids but it may also respond to azathioprine, minocycline or clofazimine.

Adult↗
PubMed1995

Antigenic comparison of Canadian and US isolates of porcine reproductive and respiratory syndrome virus using monoclonal antibodies to the nucleocapsid protein.

Fifteen Canadian field isolates of porcine reproductive and respiratory syndrome (PRRS) virus from Quebec and Ontario were compared with 5 US PRRS virus (PRRSV) isolates and with the European Lelystad isolate using monoclonal antibodies (MAbs) SDOW17, EP147, and VO17 directed to the 15-kDa nucleocapsid protein of PRRSV. All Canadian and US isolates tested by indirect immunofluorescence were recognized by the 3 MAbs, and individual titers of MAbs towards Canadian and US PRRSV isolates were similar as well. In contrast, the Lelystad virus isolate reacted only with the SDOW17 MAb and showed no reactivity with either EP147 or VO17. The reactivity pattern with these MAbs suggests that the Canadian isolates of PRRSV tested are antigenically similar to US isolates of PRRSV, and that these North American isolates share highly conserved epitopes on the 15-kDa nucleocapsid protein that clearly differentiate them from the European Lelystad virus isolate.

Animals↗
PubMed1994

Serum immune responses to the proteins of porcine reproductive and respiratory syndrome (PRRS) virus.

The antibody responses of pigs to porcine reproductive and respiratory syndrome virus (isolate VR-2332) were evaluated by indirect immunofluorescence, virus neutralization, and immunoblotting. All pigs in each group were positive by indirect immunofluorescence 14-21 days postexposure (DPE), and antibodies to specific viral proteins (15, 19 or 26 kD) were initially demonstrated by immunoblotting at 7-21 days DPE. Neutralizing antibodies were detected in only 2 pigs that were inoculated intranasally and given additional parenteral injections with adjuvant. These antibodies appeared much later, 51-70 DPE, than did antibodies detected by indirect immunofluorescence. The titer of the neutralizing antibodies increased until 127 DPE, after which the titers decreased, and 1 animal became seronegative for neutralizing antibody by 262 DPE.

Animals↗
PubMed1993

Differentiation of U.S. and European isolates of porcine reproductive and respiratory syndrome virus by monoclonal antibodies.

Monoclonal antibodies (MAbs) to two U.S. isolates of porcine reproductive and respiratory syndrome (PRRS) virus were prepared. Two MAbs specifically recognized a conserved epitope on the putative 15-kDa nucleocapsid protein of U.S. and European isolates of PRRS virus. Four other MAbs recognized epitopes on the 15-kDa protein of U.S. but not European isolates of PRRS virus. Collectively, this indicates that PRRS viruses contain both conserved and divergent epitopes on the 15-kDa viral protein.

Animals↗
PubMed1993

Clinical signs and lesions in gnotobiotic pigs inoculated with Shiga-like toxin I from Escherichia coli.

Gnotobiotic pigs were used as a model to study the contribution of Shiga-like toxin I to natural disease caused by enterohemorrhagic Escherichia coli in calves and human beings. Eleven 2- to 7-day-old gnotobiotic pigs of either sex, obtained by closed hysterotomy, were injected intramuscularly with graded doses of partially purified Shiga-like toxin I derived from a lysogenized Escherichia coli strain. Four other gnotobiotic pigs were injected with a mock toxin preparation obtained from a nonlysogenized culture of the same E. coli strain. All toxin-injected pigs developed diarrhea, and three displayed signs of neurologic disease. Pigs either died or were euthanatized 2 to 4 days post-inoculation. Necrosis of muscle was grossly evident at the site of injection in all toxin-inoculated pigs. Hemorrhage in the lumen of the small and large intestines and blood in the feces were also evident in two toxin-inoculated pigs. Microscopically, severe necrotizing myositis at the injection site, multifocal encephalomalacia, and mucosal infarcts and hemorrhage in the small and large intestines were seen. In small vessels at lesion sites, endothelial cells were frequently swollen or necrotic. Pigs inoculated with mock toxin did not develop diarrhea or exhibit signs of neurologic disease, and the only apparent lesion was mild microscopic myositis at the injection site in 1/4 pigs. The results of this study indicate that Shiga-like toxin I causes vascular damage and ischemic necrosis in the intestines and brains of gnotobiotic pigs. These lesions are similar to those seen in the intestines of calves and human beings with hemorrhagic colitis and in the brains of human beings with thrombotic thrombocytopenic purpura.

Animals↗
PubMed1993

Control beliefs of adults in three domains: a new assessment of perceived control.

Preliminary analyses (N = 205; age range 30 to 80 years) were performed with a new measure of perceived control to assess control beliefs in specific domains, examine cross-sectionally groups' age differences in perceived control and compare control beliefs for the various domains within age groups. This measure was hypothesized to yield greater conceptual clarity of the assessment of perceived control than other instruments by measuring specifically beliefs about control over desired outcomes without confounding these with beliefs about what it takes to get desired outcomes. Factor analyses clearly supported separation of control in the cognitive, social, and health domains. Intercorrelations indicated generally low relations among the three factors, and internal consistencies indicated satisfactory reliability. Participants in their 70s showed in the cognitive domain significantly lower perceptions of control than individuals in their 30s, 40s, and 50s, in the health domain significantly lower perceptions of control than individuals in their 60s, and in the social domain significantly lower perceptions of control than individuals in their 40s and 50s. Generally, for all three domains a stability in in control beliefs appeared across the age groups studied until the 70s, at which age there was a significant drop in mean control beliefs. Mean differences in control beliefs among domains within age groups were nonsignificant.

Adult↗
PubMed1992

Aged heterogeneity: fact or fiction? The fate of diversity in gerontological research.

Studies examining age-related changes typically report findings as age-based generalizations that neglect the phenomenon of variability in gerontological research. This paper examines the degree of attention given in 185 studies to individual differences and the empirical patterns of variability reported in those studies that present measures of dispersion. Measures of dispersion were reported in 43% of the gerontological studies reviewed and in 24% of the developmental studies. Overall, a majority of all gerontological studies presenting data reported increases in variability with increasing age (65%). This pattern was more pronounced in longitudinal studies than in cross-sectional ones.

Aging↗