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Biomedical subjects

L A Ward

Publications and source records attributed to L A Ward.

33 records · Page 2Linked to original sources
PubMed1996

Systematic and intestinal antibody-secreting cell responses and correlates of protective immunity to human rotavirus in a gnotobiotic pig model of disease.

Neonatal gnotobiotic pigs orally inoculated with virulent (intestinal-suspension) Wa strain human rotavirus (which mimics human natural infection) developed diarrhea, and most pigs which recovered (87% protection rate) were immune to disease upon homologous virulent virus challenge at postinoculation day (PID) 21. Pigs inoculated with cell culture-attenuated Wa rotavirus (which mimics live oral vaccines) developed subclinical infections and seroconverted but were only partially protected against challenge (33% protection rate). Isotype-specific antibody-secreting cells (ASC were enumerated at selected PID in intestinal (duodenal and ileal lamina propria and mesenteric lymph node [MLN]) and systemic (spleen and blood) lymphoid tissues by using enzyme-linked immunospot assays. At challenge (PID 21), the numbers of virus-specific immunoglobulin A (IgA) ASC, but not IgG ASC, in intestines and blood were significantly greater in virulent-Wa rotavirus-inoculated pigs than in attenuated-Wa rotavirus-inoculated pigs and were correlated (correlation coefficients: for duodenum and ileum, 0.9; for MLN, 0.8; for blood, 0.6) with the degree of protection induced. After challenge, the numbers of IgA and IgG virus-specific ASC and serum-neutralizing antibodies increased significantly in the attenuated-Wa rotavirus-inoculated pigs but not in the virulent-Wa rotavirus-inoculated pigs (except in the spleen and except for IgA ASC in the duodenum). The transient appearance of IgA ASC in the blood mirrored the IgA ASC responses in the gut, albeit at a lower level, suggesting that IgA ASC in the blood of humans could serve as an indicator for IgA ASC responses in the intestine after rotavirus infection. To our knowledge, this is the first report to study and identify intestinal IgA ASC as a correlate of protective active immunity in an animal model of human-rotavirus-induced disease.

Animals↗
PubMed1996

Morphologic changes and immunohistochemical detection of viral antigen in ovaries from cattle persistently infected with bovine viral diarrhea virus.

OBJECTIVE: To identify morphologic differences in ovaries from cows persistently infected with bovine viral diarrhea virus (BVDV) and determine ovarian cell types infected in these cows. DESIGN: A comparative study of ovaries in cattle persistently infected with BVDV and cattle not persistently infected with BVDV, using morphologic and immunohistochemical analysis. ANIMALS: 6 postpubertal cows persistently infected with BVDV and 6 postpubertal cows not persistently infected with BVDV. PROCEDURE: Ovaries were compared morphologically by counting the number of normal structures present on 3 histologic sections taken from each ovary. Immunohistochemistry was accomplished, using an indirect, monoclonal antibody-linked, avidin-biotin-peroxidase complex procedure. RESULTS: Significant (P < 0.01) decrease in the number of tertiary follicles, graafian follicles, atretic follicles, and corpus hemorrhagicum/luteum/albicans was observed in cows persistently infected with BVDV. No difference in numbers of primordial or secondary follicles was observed. Immunostaining of BVDV antigen in luteal cells and macrophage-like cells was evident in ovaries from cows persistently infected with BVDV. CONCLUSIONS: Cows persistently infected with BVDV appear to have significant morphologic changes in their ovaries that suggest reduction in normal ovarian activities. Furthermore, BVDV antigen can be identified in specific ovarian cell types in cattle persistently infected with BVDV. CLINICAL RELEVANCE: The changes observed may reduce reproductive performance in cows persistently infected with BVDV, and may be of importance when trying to salvage valuable genetic material from persistently infected cows through embryo transfer. It is yet to be determined whether similar findings are true in cows acutely infected with BVDV.

Animals↗
PubMed1995

Neuron-specific regulation of major histocompatibility complex class I, interferon-beta, and anti-viral state genes.

The regulation of major histocompatibility complex (MHC) class I, interferon (IFN)-beta, and anti-viral state expression in neurons was analyzed. Treatment of neurons with either double-stranded RNA (poly I: poly C) or virus, but not IFNs, induced high levels of IFN-beta, but not MHC class I genes. However, neurons treated with IFN-beta established an anti-viral state. Transfection of neurons with IFN-beta constructs showed that a region containing PRDI (IRF-E site) and PRDII (kappa B site) mediated induction, but closely related sites in a MHC class I construct did not. Gel mobility shift assays indicated that transcription factors containing the RelA (p65) component of NF-kappa B, but not p50, bound to PRDII. PRDI, however, bound to transcriptional antagonist IRF-2. Unique selective induction of these transcription factors is likely to mediate non-coordinate expression of IFN-beta, MHC class I, and anti-viral state genes in neurons.

3T3 Cells↗
PubMed1995

Nursing: an economic entity and profitable enterprise.

The concept of nursing as an economic entity and a profitable enterprise is a dramatic shift away from traditional employment structures. A move toward self-employment, self-interest, and capitalism is proposed, so that nursing may reap proper financial rewards.

Entrepreneurship↗
PubMed1994

Recurrent membranous lupus nephritis after renal transplantation: a case report and review of the literature.

Recurrent lupus nephritis in transplanted kidneys is rare. To the best of our knowledge, we report only the second case of recurrent membranous lupus nephritis in an allograft 8 years after transplantation. Unlike the first case, our patient received a transplant from a living-related donor rather than a cadaver. Disease "burn-out," the use of immunosuppressive drugs, and treatment of recurrence as rejection have all been offered as possible explanations for the rarity of recurrence. The majority of cases represent recurrence of the proliferative lesions, although a variety of histologic patterns and transformations have been reported.

Adult↗
PubMed1987

Isolation from swine feces of a bacterium which decarboxylates p-hydroxyphenylacetic acid to 4-methylphenol (p-cresol).

An obligate anaerobe has been isolated from swine feces which decarboxylates p-hydroxyphenylacetic acid to 4-methylphenol (p-cresol). The bacterium was an ovoid rod, gram positive, nonsporeforming, and nonmotile. Lactate and acetate were major end products of glucose fermentation. Based on its characteristics, the bacterium is tentatively assigned to the genus Lactobacillus.

Animals↗
PubMed1982

Microsticks as solid-phase carriers for enzyme-linked immunosorbent assays.

Microsticks are machine-tooled or molded pegs of plastic or stainless steel which were developed as solid-phase carriers for the enzyme-linked immunosorbent assay (ELISA). They consist of a stem, which can be coated with plastic to be used as the reactive surface, and a shaft designed for easy handling and labeling and for positioning the sticks in microtiter wells and transfer plates. Microsticks permit a wide selection of coating materials and afford the user greater control over quality and standardization of the solid-phase surface. Polycarbonate and nitrocellulose coatings were tested in ELISAs for antibodies to measles virus, toxoplasma, and human gamma globulin. The Microsticks were found to give reproducible, sensitive, and specific ELISA results and minimized problems due to lot-to-lot and batch-to-batch variations found with other plastic carriers.

Antibodies↗
PubMedDate not supplied

Rapid methods to isolate Cryptosporidium DNA from frozen feces for PCR.

The polymerase chain reaction (PCR) offers one of the most sensitive methods for detecting Cryptosporidium parvum but its sensitivity in fecal material can be greatly reduced by a variety of poorly defined 'inhibitors'. Methods that separate the parasitic oocyst from fecal material prior to DNA extraction circumvent inhibitor interference but are problematic for frozen specimens since 'intact' oocysts are required for separation. We report here a relatively low-cost, rapid method for extracting C. parvum DNA from frozen fecal materials that can be used in a PCR assay for detection of single parasitic oocysts.

Animals↗
PubMedDate not supplied

Pathogenicity, transmissibility, and tissue distribution of avian pneumovirus in turkey poults.

The pathogenicity, transmissibility, tissue distribution, and persistence of avian pneumovirus (APV) in turkey poults were investigated in three experiments. In the first experiment, we inoculated 2-wk-old commercial turkey poults oculonasally with APV alone or in combination with Bordetella avium. In the dually infected group, clinical signs were more severe, the virus persisted longer, the bacteria invaded more respiratory tissues, and the birds had higher antibody titer than the group exposed to APV or B. avium alone. In the second experiment, we studied the distribution of APV in different tissues in experimentally inoculated 2-wk-old commercial turkey poults. Only samples from sinuses, tracheas, and lungs were positive for APV by both reverse transcriptase-polymerase chain reaction and virus isolation. In the third experiment, we studied the ability of APV to spread among birds in 1-wk-old commercial turkey poults inoculated oculonasally. The virus was isolated and the viral RNA was detected in the inoculated and direct contact birds. The virus was not isolated, viral RNA was not detected, and no antibodies were detected in the indirect contact birds. These birds were placed in different cages in the same room where the airflow was directed from the infected toward the uninfected indirect contact group.

Animals↗
PubMedDate not supplied

Effect of diffferent levels of maternally derived antibodies on protection against infectious bursal disease virus.

Fertile eggs were obtained from three different broiler breeder flocks with different levels of virus neutralizing antibodies to infectious bursal disease virus. Egg yolk from these flocks was tested for antibody titers by the virus neutralization test. Flock I eggs had no antibodies, flock II had medium level antibodies (1:200-1600; geometric mean = 1:975), and flock III had a high level of antibodies (1:1600-6400; geometric mean = 1:3365). Chicks from the above flocks were challenged each with 10(2) 50% embryo infective dose of the IN serotype 1 variant virus at 1, 2, and 4 wk of age and examined at 5 and 11 days postchallenge. The average organ/body weight ratios were calculated and statistically analyzed. Chicks with no maternal antibodies were not protected at any age. Chicks with medium levels of maternal antibodies were protected when challenged at 1 and 2 wk of age. Chicks with high levels of maternally derived antibodies were protected when challenged at all the ages tested. The above results were statistically significant (P < 0.05).

Age Factors↗
PubMedDate not supplied

Experimental bovine coronavirus in turkey poults and young chickens.

The DB2 calf strain of bovine coronavirus (BCV) was used to inoculate 1-day-old specific-pathogen-free (SPF) turkey poults in three trials. In all trials, the birds developed clinical signs of enteritis at 48-72 hr postinoculation. Birds euthanatized at 3, 5, and 7 days postinoculation (DPI) had flaccid, pale intestines with watery contents, and the ceca were markedly enlarged with frothy contents. Coronavirus particles were detected by immune electron microscopy with BCV antibodies from the intestinal contents of birds killed at 3, 5, 7, and 12 DPI. Body weights of inoculated poults killed at 3, 5, and 7 DPI were significantly reduced as compared with controls. Hemagglutinating antibodies were detected in sera of convalescent birds at 12 DPI. However, experimental inoculation of 1-day-old SPF chicks in two trials with the same virus resulted in no clinical signs or macroscopic or microscopic lesions. No coronaviruses were detected from intestinal contents, and there were no significant differences in body weights of inoculated and noninoculated control chicks.

Animals↗
PubMedDate not supplied

Pathogenicity, attenuation, and immunogenicity of infectious bursal disease virus.

An investigation was conducted in specific-pathogen-free chickens on the pathogenicity of bursa-derived and tissue culture-attenuated classic (STC) and variant (IN) serotype 1 strains of infectious bursal disease virus. The IN bursa-derived virus caused bursal inflammation, necrosis, and atrophy earlier than the bursa-derived STC virus. Both viruses lost their pathogenicity after four passages in BGM-70 cells. A statistically significant level (P < 0.05) of protection was observed in SPF chickens vaccinated with the attenuated IN virus used as a live or inactivated vaccine followed by homologous (IN) and heterologous (STC) challenge with bursa-derived viruses.

Animals↗
PubMedDate not supplied

Antigenicity, pathogenicity, and immunogenicity of small and large plaque infectious bursal disease virus clones.

A serotype 1 variant strain of infectious bursal disease virus designated IN was passaged 40 times in BGM-70 cell line. A small plaque (SP) clone and a large plaque (LP) clone were then isolated and plaque purified four times. The SP and LP viruses formed circular plaques about 0.5 mm and 6.0 mm in diameter, respectively. Both clones lost their pathogenicity for specific-pathogen-free (SPF) chickens and did not elicit significant levels of virus-neutralizing antibody titers. However, the SP and LP clones maintained their immunogenicity when used as inactivated vaccines in SPF chickens. The restriction enzyme profiles of both clones were similar. Back passage of the SP and LP clones in SPF chickens resulted in loss of their phenotypic characteristics.

Animals↗