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Biomedical subjects

A A Bickford

Publications and source records attributed to A A Bickford.

At least 19 recordsLinked to original sources
PubMed2004

Hexamita meleagridis (Spironucleus meleagridis) infection in chukar partridges associated with high mortality and intracellular trophozoites.

An outbreak of infectious catarrhal enteritis, associated with the flagellated protozoan Spironucleus meleagridis (syn. Hexamita meleagridis), is reported from a commercial flock of chukar partridges in California. The disease affected birds between the ages of 4 and 6 wk and resulted in diarrhea, listlessness, depression, and high mortality. Concurrent infection with other intestinal pathogens, including Cryptosporidia, group E Salmonella, long-segmented filamentous microorganisms (LSFMOs), and Rotavirus-like virus particles, was found in some but not all affected birds. Dermatitis of the face, shanks, and feet, suggestive of B-complex vitamin deficiency, was present in most affected birds as well. Flagellated protozoan parasites could be found in the lumen of the duodenum and jejunum and in the intestinal crypts. In some cases the flagellates were wedged between epithelial cells or were located intracellularly within cells of the mucosal epithelium and the intestinal lamina propria.

Animals↗
PubMed2003

Postural and neurological deficits in broiler chicks after cervical vaccination with live vaccine.

A disease characterized by paresis and paralysis was seen in 7-9-day-old broiler chicks after vaccination in the neck area at day-of-age with a live virus vaccine containing viruses of Marek's disease, fowl pox, and infectious bursal disease. Affected birds presented with variable signs of ataxia, lateral recumbency, leg paralysis, and twisting or S-shaped flexure of the neck. Gross lesions noted at necropsy included swelling and edema of the subcutaneous tissues and muscles of the neck at the injection site area. A heavy mononuclear inflammatory cell infiltration was seen in the subcutaneous tissues, connective tissues, and muscles of the neck at the injection site. In some cases, the inflammatory process extended along fascial planes to involve the epidural spaces surrounding the spinal cord. Fatty changes with possible demyelination of nerve fibers were noted in some sections of the spinal cord adjacent to the inflammatory lesions. Clusters of poxviruses were found within some inflammatory lesions on transmission electron photomicrographs.

Animals↗
PubMed1999

Complementary randomly amplified polymorphic DNA (RAPD) analysis patterns and primer sets to differentiate Mycoplasma gallisepticum strains.

Randomly amplified polymorphic DNA (RAPD) analysis was used to differentiate 7 strains of Mycoplasma gallisepticum. Six commercially available primers or primer combinations were screened for their ability to differentiate vaccine and type strains. Although major and minor bands were produced with each primer, many of the primers were unsuitable for strain differentiation. The use of primer 6 and combined primers 3 and 4 resulted in complementary RAPD banding patterns for each M. gallisepticum strain. Eleven different isolates representing 7 different strains were segregated into 7 different patterns, corresponding to the 7 strains.

Amino Acid Sequence↗
PubMed1999

Randomly amplified polymorphic DNA (RAPD) analysis of Mycoplasma gallisepticum isolates from turkeys from the central valley of California.

Randomly amplified polymorphic DNA (RAPD) analysis was used to investigate the molecular epidemiology of 26 Mycoplasma gallisepticum (MG) isolates obtained from turkeys located in the central valley of California. The MG isolates were recovered from 5 different companies and 13 ranches. Each company had unique MG strains. No evidence of spread of MG between companies was detected. RAPD analysis of MG isolates within a ranch during an outbreak revealed only a single strain involved in each outbreak. RAPD analysis identified an isolate from 1 ranch with a banding pattern identical to that of the 6/85 vaccine strain, which had been used on that particular ranch. Similar RAPD banding patterns of isolates from different ranches within the same company suggested horizontal spread of MG between ranches. The use of 2 primer sets in RAPD analysis was critical to prevent misinterpretation of relationships between different isolates.

Animals↗
PubMed1995

Apoptosis as a cause of death in chicken embryos inoculated with Newcastle disease virus.

Eleven-day-old chicken embryos were inoculated by the allantoic route with the GB strain of Newcastle disease virus (NDV). At 0, 24, 36 and 42 h post-inoculation (p.i.), the brain and heart tissues were harvested for DNA extraction, and the thymus and the brain were fixed and processed for light and electron microscopy. At 42 h p.i., most of the embryos had died; however, no histopathological changes could be seen in the embryos at any stage of infection. DNA extracted from the brain cells started showing fragmentation at 24 h p.i., and from the heart muscle cells at 36 h p.i. Electron microscopy of the brain and thymus showed condensation of the nuclear chromatin, apoptotic bodies, various forms of crescent formation and some evidence of necrosis. Fragmentation of cellular DNA, crescent formation and apoptotic bodies are the typical signs of cells undergoing apoptosis. We suggest that apoptosis of the heart and brain is probably a cause of death of chicken embryos in acute Newcastle disease infection.

Animals↗
PubMed1993

Preliminary characterization of a pleomorphic gram-negative rod associated with avian respiratory disease.

An unidentified, pleomorphic, gram-negative rod (PGNR) bacterium has been isolated from domestic fowl with respiratory disease. The PGNR was isolated in 5% of turkey accessions and 3% of chicken accessions, primarily from the respiratory tract. Preliminary characterization of this organism included reviewing accession records, conducting cultural and biochemical tests, and analyzing cellular fatty acids. The PGNR was also compared with other bacteria capable of inhabiting the avian respiratory system. Biochemical and cellular fatty acid analysis failed to identify the organism, however all 14 isolates were similar.

Animals↗
PubMed1989

Association of Reoviridae particles in an enteric syndrome of poults observed in turkey flocks during 1988.

An enteric syndrome of turkey poults, characterized by enteritis, crop mycosis, intestinal changes (pale, thin-walled ballooning with watery contents), and rickets, occurred during 1988 in 74 turkey flocks from different farms belonging to 9 California turkey growers. The flocks ranged in size from 9,000 to 120,000 birds. Pools of intestine sections from 618 birds, representing 78 field cases, were examined. Histopathological examination of the intestines showed a mild to severe atrophy with a reduced depth of crypts, which was more prominent in the distal part of the small intestine. Viral isolation attempts with primary cell cultures of chicken embryo kidney cells were negative. Examination by electron microscopy of negatively stained intestinal specimens revealed the presence of Reoviridae particles of 58.8 to 80 nm in diameter. Enzyme-linked immunosorbent assay results on the intestinal pools for mammalian and group A avian rotaviruses were negative. A statistically significant relationship was found for the presence of Reoviridae particles in the intestines of 10-21-day-old birds. Of the 7 most common pathological conditions analyzed, 2, rickets and intestinal changes (thin-walled ballooning intestine with watery contents), showed a statistically significant association with the presence of Reoviridae particles.

Age Factors↗
PubMed1989

Role of harderian glands in resistance against Mycoplasma gallisepticum challenge.

Harderian glands of one-day-old chickens were surgically removed. At one week old, these chickens and controls from which these tissues were not removed, were vaccinated intranasally with a temperature-sensitive mutant of Mycoplasma gallisepticum. Humoral and local immunity were measured by means of antibody in sera and tracheal washings, respectively. Protection was measured by resistance to intra-air-sac challenge with the S6 strain of M gallisepticum. There was no discernible difference in either humoral or local antibody response between vaccinated chickens from which the glands had been removed and control birds. In addition, both groups were significantly protected against air-sac challenge compared with unvaccinated controls. These results indicate that removal of the Harderian glands neither affects the production of antibody to M gallisepticum, nor alters the effectiveness of temperature-sensitive M gallisepticum vaccination. The role that the Harderian glands play in resistance to M gallisepticum is therefore questioned.

Air Sacs↗
PubMed1986

Necropsy of chickens, turkeys, and other poultry.

Necropsy of dead or terminally ill birds is a key approach to disease diagnosis. It is important that one establish an orderly, consistent necropsy procedure and evaluate gross lesions as to their likely cause and significance. A very high percentage of farm flock poultry maladies can be diagnosed by gross lesions plus a few simple laboratory procedures, such as direct microscopy, Gram's stain, fecal flotation, and aerobic bacteriology.

Animals↗
PubMed1984

Assessment of the delayed neurotoxic potential of isopropyl triphenylphosphate using a nontraditional testing strategy.

The potential of isopropyl triphenyl phosphate (ITP) to produce delayed neurotoxicity in hens was examined using several techniques. ITP contained O,O,O-triphenyl phosphate (24%), O-o-isopropylphenyl O,O-diphenyl phosphate (25%), O,O-diisopropyl-phenyl O-phenyl phosphate (20%), O-o, p-diisopropylphenyl O,O-diphenyl phosphate (18%) and O-p-isopropylphenyl O,O-diphenyl phosphate (6%). Hens treated twice, 3 wk apart, with doses of ITP as high as 11.7 g/kg showed no clinical signs of delayed neurotoxicity and only mild signs of general toxicity. Furthermore, none showed even subtle neurohistologic changes suggestive of delayed neurotoxicity. ITP produced dose-dependent inhibition of hen plasma cholinesterase and brain neurotoxic esterase (NTE). The study was continued because NTE inhibition has been shown to be a reliable predictor of organophosphates that produce delayed neurotoxicity. ITP was administered prior to tri-o-tolyl phosphate (TOCP) challenge in order to determine if it altered development of TOCP delayed neurotoxicity. ITP neither enhanced nor reduced the onset or severity of neurotoxicity produced by TOCP. The time-course for brain and spinal cord NTE inhibition by ITP and TOCP were compared and found to be different. The maximum brain NTE inhibition produced by ITP (doses up to 11.7 g/kg) was never complete (always less than 90%), and spinal cord NTE inhibition was significantly less than that produced in the brain. In contrast, brain and spinal cord inhibition produced by 500 mg TOCP/kg were equal and greater than 90%. This testing regimen showed that ITP produced an effect on NTE at the biochemical level without producing clinical or neurohistologic abnormalities in treated hens. Furthermore, this biochemical effect was qualitatively different than that produced by the delayed neurotoxicant TOCP.

Animals↗