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Biomedical subjects

J A Frazier

Publications and source records attributed to J A Frazier.

49 records · Page 3Linked to original sources
PubMed1984

Left ventricular performance in patients with coexistent mitral stenosis and aortic insufficiency.

Isolated mitral stenosis and isolated aortic insufficiency impose unique and opposite loading conditions on the left ventricle. To assess these combined effects, hemodynamic and angiographic factors were compared among normal subjects and patients with isolated mitral stenosis, isolated aortic insufficiency or combined mitral stenosis and aortic insufficiency. Left ventricular end-diastolic volume index was lower in patients with combined lesions and severe or moderate aortic insufficiency than in patients with isolated severe or moderate aortic insufficiency (138 +/- 19 versus 206 +/- 20 cc/m2 and 87 +/- 5 versus 145 +/- 22 cc/m2, respectively) (p less than 0.05 for both). Left ventricular end-diastolic and end-systolic volume indexes were normal in two-thirds of patients with combined lesions and moderate or severe aortic insufficiency, whereas these indexes were high in all but one patient with isolated moderate or severe aortic insufficiency. Among patients with moderate or severe aortic insufficiency, 8 of 14 with isolated insufficiency had a reduced ejection fraction or circumferential fiber shortening rate compared with 5 of the 9 patients with combined lesions. Among patients with isolated aortic insufficiency, left ventricular end-systolic wall stress and end-diastolic and end-systolic volume indexes were higher (p less than 0.05) in those with reduced ejection performance than in those with normal ejection performance. These variables did not differ between patients with reduced or normal ejection performance in the group with combined lesions. The contractile index (ratio of end-systolic wall stress to end-systolic volume index) was significantly depressed in patients with severe aortic insufficiency in the groups with isolated aortic insufficiency or combined lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1979

Ultrastructural studies on erythropoiesis in the avian thymus. I. Description of cell types.

Thymus lobes from three species of birds, Quelea quelea, Passer domesticus and Sturnus vulgaris, have been examined ultrastructurally. The component cell types are compared with their counterparts in mammalian thymus glands, and found to be similar. Greater differences between small, intermediate and enlarged lobes of one species than exist between species. Developing erythroid cells are present in most enlarging and some enlarged glands. They appear to be developing at the expense of lymphoid cells in some birds. The origin of these cells is discussed. Cells that are possible candidates for the production of some thymic hormones are also described.

Animals↗
PubMed1975

The ultrastructure of lymphoblastoid cell lines from Marek's disease lymphomata.

The ultrastructure of two lymphoblastoid cell lines derived from Marek's disease lymphomata has been studied. The cells varied from 5 to 12 mum in diameter and had large round or oval nuclei. A nucleolus was occasionally present and about 3% of cells showed projections of the nuclear envelope. The cytoplasm contained many ribosomes and several mitochondria but endoplasmic reticulum was sparse. A small number of cells contained annulate lamellae and crystalline structures were occasionally seen. Cells with immature intranuclear herpesvirus particles were rarely present. The cells had many ultrastructural features in common with Burkitt's lymphoma-derived cell lines.

Animals↗
PubMed1975

Characterization of a new serotype of Marek's disease herpesvirus.

The HPRS-24 strain of Marek's disease herpesvirus was selected for closer study from a group of virus isolates that appeared apathogenic under standard test conditons. Protection studies revealed an immunological relationship between this virus strain and acute Marek's disease herpesvirus. In chicken kidney cell cultures, the HPRS-24 strain caused small and slowly developing plaques, and the proportion of infected cells was less than with other strains. In chicken embryo fibroblast cultures, this virus multiplied rapidly, yielding a comparatively high proportion of infected cells. Electron microscopic studies revealed that infected fibroblasts contained more enveloped virus particles than those infected with other strains of Marek's disease herpesvirus. Infectious cell-free virus was extracted from cultured fibroblasts with titres high enough for use in neutralization studies. Cross-neutralization, immunofluorescence and precipitin tests served for serological comparison of the HPRS-24 strain with turkey herpesvirus and representatives of acute and classical Marek's disease herpesvirus. Antibody titres were 4-10 times higher against the homologous than against the heterologous virus strains. Qualitative differences between precipitating "A" antigens were characterized by spur line patterns of precipitation bands. These results suggest that the group of Marek's disease and turkey herpesviruses consists of at least three serological types. One of them is represented by the HPRS-24 strain of apathogenic Marek's disease virus. The other two types comprise pathogenic strains of Marek's disease virus and their attenuated variants, and turkey herpesvirus.

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PubMed1975

T-lymphoblastoid cell lines from Marek's disease lymphomas.

The establishment and continuous culture of two lymphoblastoid cell lines derived from Marek's disease lymphomas is described. Although the cells carried T-lymphocyte surface antigens, they had many features in common with cultured Burkitt's lymphoma lymphoblasts, which carry B-cell determinants. A small proportion acted as infectious units in tissue culture, and a similarly small proportion contained intranuclear immature herpesvirus particles. The cells did not respond to phytohaemagglutinin. One cell line possessed some graft-versus-host capacity, as measured by the induction of splenomegaly. It is concluded that the development of acute Marek's disease involves the malignant transformation of thymus-dependent lymphocytes by Marek's disease virus.

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PubMedDate not supplied

Experimental factors affecting mortality following inoculation of chickens with avian nephritis virus (G-4260).

Groups of approximately 20 one-day-old chickens were inoculated with G-4260, the reference strain of avian nephritis virus (ANV), or saline. Based on mortality rates from severe nephritis in comparable experiments, light Sussex chickens generally were more susceptible than Rhode Island red (RIR) chickens. Mortality was greater in those given broiler starter than those given other feeds, and was greater when light Sussex chickens were given broiler starter feed and cold-stressed at 15 +/- 1 C for 2 hr daily during the first week rather than brooded normally. Inoculation with G-4260 either orally or by intraperitoneal injection produced similar results in RIR chickens. Thirty-three inoculated chickens died of severe nephritis between 4 and 12 days postinoculation, and 24 (73%) of them had visceral urate deposits. Inoculated inbred white leghorn Line 15 chickens with maternal antibody to ANV were brooded normally and given broiler feed: they were susceptible to infection as evidenced by subsequent histological lesions in the kidneys and serology, but mortality was not a feature. There were no deaths from nephritis in inoculated non-inbred white leghorn chickens free of maternal antibody to ANV that were given broiler feed and brooded normally. These results have implications in standardizing experimental conditions for the study of mortality induced by G-4260 and similar viruses.

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PubMedDate not supplied

Escherichia coli multiplication and lesions in the respiratory tract of chickens inoculated with infectious bronchitis virus and/or E. coli.

Escherichia coli numbers and histopathological changes were studied in the respiratory tract of line 151 chickens intranasally inoculated with infectious bronchitis virus (IBV) and/or virulent E. coli; this line is highly susceptible to IBV. Chickens inoculated with IBV alone showed increased numbers of E. coli in the trachea and had tracheitis, airsacculitis, and bronchiolitis. One of 17 chickens inoculated with IBV alone died with fibrinopurulent serositis. Chickens inoculated with IBV and E. coli had more severe and persistent respiratory lesions than those inoculated with IBV alone. E. coli was isolated from tracheas of chickens inoculated with IBV and E. coli more frequently than from chickens inoculated with IBV alone. In this group, 14 of 27 chickens died with tracheal plugs or with fibrinopurulent serositis. There was neither increased numbers of E. coli nor significant lesions in the respiratory tract of the group inoculated with E. coli alone. These results suggest that IBV may facilitate E. coli invasion into the lower respiratory tract of the chicken.

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