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Biomedical subjects

Y S Lu

Publications and source records attributed to Y S Lu.

At least 73 records · Page 4Linked to original sources
PubMed1985

High-pressure liquid chromatographic assay and pharmacokinetics of HR 810 after intramuscular injection in rabbits.

A high-pressure liquid chromatographic assay was developed for the detection of HR 810 in rabbit plasma. There was no interference in the high-pressure liquid chromatographic assay from other antibiotics. The method was accurate, reproducible, and capable of detecting less than 1 microgram of HR 810 per ml in plasma. The assay correlated with the microbiological assay (correlation coefficient, 0.93) and was used to quantitate the concentration of HR 810 in rabbit plasma and determine its half-life subsequent to a 20-mg/kg intramuscular dose. The peak concentration of HR 810 was 51.2 +/- 8.0 micrograms/ml at 1 h postdose. The half-life of the absorption phase (mean +/- standard deviation) was 0.35 +/- 0.10 h, and the half-life of the elimination phase was 0.75 +/- 0.06 h. This is 54% less than the half-life of elimination of 1.38 h previously reported for the intravenous dose.

Animals↗
PubMed1983

Capsular and somatic serotypes of Pasteurella multocida isolates recovered from healthy and diseased rabbits in Texas.

A total of 111 Pasteurella multocida isolates recovered from healthy and diseased rabbits were typed for capsular and somatic antigens by the typing systems of Carter and Heddleston, respectively. The major serotypes of the 48 P. multocida isolates recovered from nasal cavities of healthy rabbits were serotypes 12:A (33%), nontypable:A (50%), and nontypable:D (10%). Similarly, the major serotypes of the 63 P. multocida isolates obtained from rabbits with rhinitis, pneumonia, conjunctivitis, tympanitis, or cutaneous abscesses were serotypes 12:A (32%), nontypable:A (30%), and 3:A (16%). Serotype 12:A was predominant, regardless of whether the isolates were recovered from healthy or diseased rabbits.

Animals↗
PubMed1982

Acute hepatitis in an opossum (Didelphis virginiana) infected with Salmonella turnidorp.

Salmonella turnidorp was isolated in pure culture from the liver of an opossum that died of acute hepatitis. Microscopically, there were random foci of hepatic coagulation necrosis and gram negative bacteria within hepatocytes. The Salmonella turnidorp isolate was aberrant in that it did not utilize citrate and did not agglutinate by a commercial Salmonella polyvalent antiserum. Additional Salmonella serotypes, including Salmonella mbandaka, Salmonella rubislaw, and Salmonella anatum were isolated from three of five healthy opossums caught in Texas.

Acute Disease↗
PubMed1982

Pathogenicity of a serotype 12:A Pasteurella multocida in hydrocortisone treated and nontreated rabbits.

A Pasteurella multocida isolate of 12:A serotype from a rabbit caused typical pulmonary pasteurellosis and death in pasteurella-free rabbits by intranasal exposure. Rabbits stressed with hydrocortisone and inoculated with 12:A Pasteurella multocida organisms developed a higher prevalence of pneumonia than rabbits not treated with hydrocortisone. Typical 12:A Pasteurella multocida was isolated from nasal cavity, trachea, and lungs and was most prevalent in nasal cavities. Surviving rabbits developed serum agar gel precipitating antibody beginning 15 days post-inoculation. The data showed that the 12:A Pasteurella multocida isolate was pathogenic, caused mortality, colonized the respiratory tract, and stimulated systemic immune response by producing serum agar gel precipitating antibody.

Animals↗
PubMed1981

Protection of rabbits against experimental pasteurellosis by a streptomycin-dependent Pasteurella multocida serotype 3:A live mutant vaccine.

Pasteurella multocida (serotype 3:A) was isolated from a rabbit with clinical signs of suppurative rhinitis. This P. multocida strain was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine to obtain a genetically stable streptomycin-dependent mutant, from which a life vaccine was prepared. Pasteurella-free rabbits were inoculated intranasally three times at weekly intervals and challenged intranasally with a virulent serotype 3:A rabbit P. multocida isolate 2 weeks after the third vaccination. The rabbits were killed 2 to 3 weeks later. The vaccine did not cause clinical disease, death, or gross or microscopic lesions. Furthermore, the vaccine protected the challenge rabbits from developing clinical disease, death, and gross lesions. However, mild focal lung lesions were noted in several of the vaccinated-challenged animals. In contrast, nonvaccinated-challenged rabbits developed pyrexia and anorexia. Furthermore, three of four of these rabbits died with severe gross lesions including pyothorax, suppurative pericarditis, and fibrinopurulent pneumonia. Microscopically, the four nonvaccinated rabbits had moderate to severe suppurative pneumonia and mild to moderate suppurative rhinitis, and two had mild tympanitis. The mutant vaccine did not appear to colonize the nasal cavities. The vaccine prevented the colonization of the virulent challenge organism in lungs, liver, spleen, genital tracts, and blood, but not the nasal cavities.

Animals↗
PubMed1979

Newcastle disease virus in Taiwan: II, Relationship between polykaryocytosis and virus virulence.

Fifteen selcted local isolates and five known Newcastle disease virus strains were examined for their cytopathic effects in chick embryo kidney (CEK) cells, egg-infectious units in chick embryos (CE), virulence by mean death time, intracerebral and intravenous pathogenicity indexes for CE and chicks, and ability to cause polykaryocytosis of fusion from within (FFWI) or fusion from without (FFWO) in CEK and BHK-21 monolayer cells. The capacity of the different virus strains to induce cell FFWI at 15 hr post-infection was related to their virulence for CE and chicks, but cell FFWO did not seem to be any relationship with the virulence of the strains.

Animals↗
PubMed1978

Characterization of Pasteurella multocida isolates from the nares of healthy rabbits with pneumonia.

Pasteurella multocida was isolated from 42 of the 135 (31%) deep nasal swabs from clinically healthy conventional rabbits supplied by two vendors. The prevalences were significantly different among sex, age, and sources. The females and adults had higher prevalences when compared to males and juveniles, respectively. One vendor's rabbits had a prevalence of 41% while the other had 20%. Biochemically, only 24% of the 42 isolates decarboxylated L-ornithine, and 55% produced indol. All isolates were sensitive in vitro to several of the commonly used antibiotics, but most isolates were resistant to lincomycin, streptomycin, and sulfonamides. Typing with a hyaluronidase inhibition test revealed that 28 of the 42 (67%) isolates were type A. Type A was the major type isolate, whether the samples came from healthy rabbits or from rabbits with pyogenic lesions. The acriflavine flocculation test showed that two of the 42 (5%) isolates were type D. Although none of the 42 isolates were positive to both hyalurondase and acriflavine tests, 12 of the 42 (29%) isolates were negative to both tests, indicating that these isolates were not typeable by these two methods. The demonstration of more than one capsular type of Pasteurella multocida in rabbits indicates the need for more extensive studies on this important rabbit pathogen.

Acriflavine↗
PubMed1976

Cyclophosphamide-induced amelioration of Marek's disease in Marek's disease-susceptible chickens.

Bursa- and thymus-dependent functions were examined in Marek's disease (MD)-susceptible normal chickens and in chickens treated with 5 and 16 mg of cyclophosphamide (CY) at the time of hatching. Chickens not exposed to Marek's disease virus (MDV) and treated with CY temporarily lost mitogenic response to concanavalin A but regained full response after 5 weeks. Bursa-dependent functions, such as presence of germinal centers in spleen and cecal tonsils, morphologic features of bursa, and sheep red blood cell antibody response were completely lost in chickens treated with 16 mg of CY and only partly retained in chickens treated with 5 mg of CY. In chickens exposed to MDV, the degree of thymus-dependent spleen cell mitogenic response was directly related to frequency and severity of MD. Chickens treated with 16 mg of CY had a mild mitogenic depression and low frequency and severity of MD lesions, whereas those treated with 5 mg of CY and those not treated had marked mitogenic depression and high frequency and severity of MD. Suppressions of bursa- and thymus-dependent functions by MDV alone were also evident when comparing MDV-exposed and nonexposed chickens. The results also indicate that presence of small, residual amounts of humoral factor(s) may enhance MDV oncogenesis.

Animals↗
PubMed1975

Effect of cyclophosphamide on the response of chickens to a virulent strain of Marek's disease virus.

The effect of cyclophosphamide on the pathogenesis of Marek's disease was examined in a line of chickens which is relatively resistant to Marek's disease. The injection of cyclophosphamide into newly hatched chickens delayed and reduced viremia and also reduced the development of Marek's disease lesions until 2 weeks after exposure to Marek's disease virus. The data indicate that a population of T cells susceptible to infection with virus and possibly viral transformation is affected by cyclophosphamide.

Animals↗
PubMed1975

Immunoglobulins and anti-Marek's disease virus antibody synthesis in chickens after passive immunization with immunoglobulin Y anti-Marek's disease virus antibody.

The effect of passive immunization with immunoglobulin Y (IgY) antibody against Marek's disease virus (MDV) was examined in MDV-susceptible chickens. The production of IgY, immunoglobulin M, and probably also immunoglobulin A was depressed in passively immunized chickens when compared with that in MDV-exposed chickens which had not been given IgY anti-MDV antibody. In passively immunized chickens, the synthesis of immunoglobulin M and IgY anti-MDV antibodies in response to MDV infection also was delayed as determined by agar gel precipitin and indirect fluorescence antibody tests.

Animals↗