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Biomedical subjects

L A Thomas

Publications and source records attributed to L A Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1985

Characterization of monoclonal antibodies protecting mice against Rickettsia rickettsii.

Hybridomas producing monoclonal antibodies to Rickettsia rickettsii were prepared from mice to investigate the function of rickettsial antigens. Of the 31 reactive hybridoma lines thus far tested for immunoglobulin subclasses, 11 belonged to the IgG2A subclass, 9 to the IgG2B subclass, and 7 to the IgG3 subclass; four did not react with any of the isotyping sera. Five of the antibodies recognized epitopes present on molecules that were presumed to be polysaccharide and heterogeneous in molecular weight. Twenty monoclonal antibodies reacted with a 170,000-dalton antigen, and six precipitated both the 133,000- and 32,000-dalton polypeptides. Only those antibodies to the 170,000- and 133,000-dalton antigens protected mice from challenge with R. rickettsii. Antibodies to these same antigens were detected in sera from patients convalescing from Rocky Mountain spotted fever. All monoclonal antibodies reacted with antigens apparently located on the rickettsial surface. The protective activity of these antibodies was not correlated with their reactivity in complement fixation, enzyme-linked immunosorbent assay, and immunofluorescence tests.

Animals↗
PubMed1985

The role of prostaglandins in feline experimental cholecystitis.

The arachidonic acid metabolites are recognized as important biochemical mediators of inflammation in a wide variety of disease processes. Also the ability to change prostaglandin formation by inhibition of prostaglandin synthetase activity with aspirin and other nonsteroidal anti-inflammatory agents is important in the treatment of many diseases with an inflammatory component. Although gallbladder disease is primarily related to the development of cholesterol stones, inflammation is an important contributor to the subsequent symptoms and accompanying illness. This research evaluates the formation of prostaglandins E and F by gallbladder tissue. Gallbladder mucosal cells and muscle tissue were maintained in tissue culture medium. Production of prostaglandins E and F was determined by quantitation by radioimmunoassay of these substances in culture media and mucosal cell and muscle tissue homogenates. Prostaglandin production by normal gallbladder tissue in a variety of species including man was consistently demonstrated in the nanogram per milligram mucosal cell or muscle tissue protein range. In cats, inflammation was produced by placing a 4% carrageenan-soaked sponge in the gallbladder, and prostaglandin synthetase inhibition was produced by indomethacin administration. The feline gallbladder increased prostaglandin F production in inflamed gallbladder mucosal cells and E production by inflamed gallbladder muscle tissue, and indomethacin inhibited these increases. A positive, significant correlation existed between the increased prostaglandin E and prostaglandin F production by inflamed gallbladder tissue and the amount of inflammation present as determined by a histologic score. The histologic score of the amount of gallbladder inflammation present was decreased significantly by indomethacin when compared with inflamed gallbladders from cats not receiving indomethacin. Prostaglandins may play a role in the inflammatory processes occurring in acute cholecystitis.

Animals↗
PubMed1984

T-cell prolymphocytic leukemia with helper-cell phenotype and a review of the literature.

The majority of published cases of prolymphocytic leukemia (PLL) have been of B-cell origin. Nineteen cases of PLL of T-cell type have been described, as has a single case of PLL having a surface phenotype with features of both B-cells and T-cells. This report presents a review of these cases and comparison with one case of T-cell PLL. By using specific monoclonal antibody technique, this case was subcategorized into helper-cell phenotype: E-rosette(+), SIG(-), Anti-T(+), Anti-B(-), Anti-monocyte(-), OKT3(+), OKT4(+), OKT6(-), OKT8(-), Ia(+), and Tdt(-). Cytochemical studies showed paranuclear acid phosphatase granules. Postmortem examination revealed a predominant T-cell zone infiltration by the leukemic cells in the spleen and lymph nodes, with involvement of multiple organs. The application of the monoclonal antibody technique, which can be standardized among different laboratories to subclassify lymphoproliferative disorders into functional subtypes, should lead to a better understanding and more effective treatment of this disease.

Aged↗
PubMed1984

Monoclonal antibodies distinguish phase variants of Coxiella burnetii.

Monoclonal antibodies (MAbs) directed against phase I and II variants of Coxiella burnetii were produced by fusing myeloma SP2/O-AG 14 cells with spleen cells from mice immunized with the chloroform-methanol extraction residue of phase I whole cells. Two hybridoma clones which distinguished the phase variants by microimmunofluorescence assay were isolated and characterized. The MAbs showing specificity for phase I cells (MAbI-1, immunoglobulin G, subclass 3 kappa) reacted with the hot phenol-water extract of phase I C. burnetii in immunodiffusion and enzyme-linked immunosorbent assays. MAbI-1 reacted with high-molecular-weight components from phase I phenol-water extract and whole cell in an immunoblot assay. Specificity of MAbI-1 for a carbohydrate epitope in the phenol-water extract was demonstrated by periodic acid inactivation of binding by a competitive enzyme-linked immunosorbent assay. Phase I antigenic sites were apparently well represented on the surface of cells as demonstrated by complete fluorescence and microagglutination. The MAb showing specificity for phase II cells (MAbII-1, immunoglobulin G, subclass 2b kappa) reacted with whole cells in the microimmunofluorescence assay, microagglutination test, complement fixation test, and the enzyme-linked immunosorbent assay. MAbII-1 reacted specifically with a 29,500-dalton surface protein as demonstrated by immunoprecipitation of 125I-surface-labeled cells. Although MAbII-1 reacted with detergent-solubilized protein, it did not react with sodium-dodecyl sulfate-denatured protein by immunoblot assay. This protein was not exposed on the surface of phase I cells, but chloroform-methanol extraction of phase I cells exposed the phase II epitope.

Animals↗
PubMed1982

Isolation and characterization of Midway virus: a new tick-borne virus related to Nyamanini.

Midway virus, a new tick-borne virus isolated from two species of Ornithodoros (Alectorobius) ticks of the capensis group (O capensis, O denmarki), is described from Midway, Kure, and Manana islands in the Central Pacific (Hawaiian Archipelago) and from northern Honshu (Japan). Midway virion is enveloped, unusually large, acid and temperature sensitive, and its type of nucleic acid is RNA. Complement-fixation (CF) tests show a close relation of Midway to Nyamanini virus, which has been isolated from ardeid birds and Argas ticks in Africa, the Indian subcontinent, and Southeastern Asia. However, cross-box tests (CF, mouse and tissue culture neutralization, immunofluorescence) show that these two viruses are quite distinct. Midway virus is lethal for newborn Swiss mice inoculated by intracerebral, but not intraperitoneal route. It fails to kill four-week-old mice by either route. Midway virus causes cytopathic effects in BHK-21 cells and titerable plaques in Vero cells. Antibodies to it were prevalent among nestlings of Larus crassirostris (Black-tailed Gull) on Aomatsushima I., but were scarce among those of Nycticorax nycticorax (Black-crowned Night Heron) of the same island.

Animals↗
PubMed1980

Antibody development in garter snakes (Thamnophis spp.) experimentally infected with western equine encephalitis virus.

Garter snakes (Thamnophis spp.) have been considered to possibly play an important role in the ecology of western equine encephalitis (WEE) virus. Serological tests (hemagglutination-inhibition, complement-fixation, neutralization test in mice, and plaque neutralization) to detect antibody in these reptiles following laboratory exposure t this virus have, in our experience, been unsatisfactory. A new test, the snake globulin precipitation (SGP) test, has been developed and we consider it to be reliable in detecting antibody in WEE virus-infected garter snakes. Antibody has been detected in these snakes over 4.5 years following inoculation with WEE virus. The SGP test should be a valuable tool in obtaining further information regarding the possible role of these cold-blooded vertebrates in the ecology of this important arbovirus.

Animals↗
PubMed1980

A serologic survey for selected infectious diseases of black bears in Idaho.

Two hundred sixty-five black bears (Ursus americanus) from northcentral Idaho were examined serologically over a five-year period for antibodies against selected infectious disease agents. The number of positive serum samples number of sera tested and percent positive for each infectious agent is: tularemia, 65/340 (19); brucellosis, 18/332 (5); toxoplasmosis, 23/303 (8); leptospirosis, 2/196 (1); trichinosis, 16/122 (13); Q-fever, 13/210 (6); St. Louis encephalitis, 3/340 (1); western equine encephalitis, 4/334 (1); Rocky Mountain Spotted Fever, 6/282 (2). Black bears may serve as an indicator for infection in other wildlife, domestic animals and humans in the area..

Animals↗
PubMed1979

Indirect hemagglutination test for detection of antibody to Rickettsia rickettsii in sera from humans and common laboratory animals.

Antibody production in humans and three species of laboratory animals infected with Rickettsia rickettsii was determined with the indirect hemagglutination test. Rabbits, guinea pigs, and mice were inoculated with R. rickettsii and bled at intervals. Antibody which agglutinated both fresh and glutaraldehyde-fixed sheep erythrocytes sensitized with antigen prepared either from purified rickettsiae or from infected yolk sacs was found in rabbit sera at all intervals tested (10 to 59 days postinfection). Antibody which agglutinated fresh but not glutaraldehyde-fixed erythrocytes sensitized with either of the above antigens was detected in guinea pig sera obtained 7, 14, and 28 days postinfection. Antibody was found in mice inoculated with 5.6 x 10(6) plaque-forming units of R. rickettsii but not in mice given 5.6 x 10(2) plaque-forming units. Peak indirect hemagglutination titers occurred in nonvaccinated human Rocky Mountain spotted fever patients about 3 weeks after onset of illness, and antibody was still detectable after 1 year. Both human immunoglobulin G and human immunoglobulin M antibodies agglutinated sensitized cells, but immunoglobulin M antibodies apparently were more efficient. The indirect hemagglutination test is useful for the titration of human, rabbit, guinea pig, and mouse antibodies when the appropriate erythrocytes are used.

Animals↗
PubMed1977

A comparison of serologic methods for diagnosis of Rocky Mountain spotted fever.

Sera referred to the North Carolina Division of Health Services for rickettsial serology in 1974 were tested by complement fixation (CF), microimmunofluorescence (micro-IF), microagglutination (MA) and hemagglutination (HA) for antibodies against Rickettsia rickettsii. There was good agreement among micro-IF,MA and HA tests in detecting antibody responses to this agent, but the CF test was definitely less sensitive than the others, even in illnesses with classical clinical manifestations of Rocky Mountain spotted fever (RMSF). Some variables that seemed to influence the CF result were the slow rate of increase in antibody titers, timing of serum collection, early antibiotic treatment and possibly, the particular association of CF antibody response with the IgG immunoliobulin class. Greater use of these newer, but relatively untried, serodiagnostic procedures is recommended infuture studies of RMSF.

Agglutination Tests↗
PubMed1977

Sunday Canyon virus, a new ungrouped agent from the tick Argas (A.) cooleyi in Texas.

A new arbovirus was isolated from Texas, U.S.A., populations of the Cliff Swallow parasits Argas (Argas) cooleyi Kohls and Hoogstraal, 1960. The virus, named Sunday Canyon, is serological urelated to any of 185 arbovirus strains or 20 other viral agents with which it was compared. Morphologically it resembles Bunyamwera viruses and, in common with them, is sensitive to lipid solvents and acid pH, and apparently possesses RNA. Although considerably resistant to a temperature of 41.5 degrees C, it rapidly loses infectivity when incubated at 56 degrees C. It is lethal for newborn white mice and infective for the Vero and Antheraea eucalypti cell lines. Sundays Canyon virus is the second tick-associated, Bunyamwera virus-like agent known from North America and the third virus to be reported from A. cooleyi in Texas.

Animals↗
PubMed1976

Viral contamination of a mosquito cell line, Aedes albopictus, associated with syncytium formation.

Viral contamination associated with syncytium formation in two sbulines of Singh's Aedes albopictus cell cultures was investigated. Electron microscopy of the syncytia revealed the presence of five different types of virus-like particles, which morphologically resembled the parvo-, picorna-, toga-, and orbi-, and bacterial viruses. When a virus-free subline of the A. albopictus cells (SL3) was inoculated with extracts of the syncytium-forming A. albopictus cells, the parvo-, toga-, and orbi-type viral agents were consistently observed. Among these three agents, the togavirus-type agent is most likely responsible for the syncytium induction. Serological examination of the infected cell extract indicated that at least one of three virus-like agents, presumably the togavirus-type agent, was related to Chikungunya. O'nyong-nyong, and Western equine encephalomyelitis viruses (alphaviruses of the Togaviridae), but separable from these.

Aedes↗
PubMed1976

Isolation of a spotted fever group rickettsia from the Pacific Coast tick, Ixodes pacificus, in Oregon.

A rickettsia of the spotted fever group was isolated on three occasions from Ixodes pacificus in western Oregon. These isolations, and additional evidence furnished by complement fixation tests on guinea pigs inoculated with other Oregon ticks of this species, indicate that the association of this rickettsia with the Pacific Coast tick may be widespread. This is the first isolation of a spotted fever group rickettsia from I. pacificus. Because the Oregon isolates are mildly virulent for guinea pigs they resemble the Western U and Rickettsia montana strains of rickettsiae. However, preliminary evidence from cross-immunofluorescence tests of mouse antisera suggests the Tillamook and Grants Pass strains are antigenically different from all known spotted fever group agents.

Animals↗
PubMed1976

Immune response in the garter snake (Thamnophis ordinoides).

Garter snakes (Thamnophis ordinoides) were immunized with hen egg albumin, human gamma-globulin and Keyhole limpet haemocyanin in Freund's adjuvant. Antibody was consistently detected by radioimmunoelectrophoresis and in three different gamma- and beta-globulin precipitin lines called IgM (approximately or equal to 20S), Ig-1 (approximately or equal to 9S) and Ig-2 (approximately or equal to 8-5S). Early antibody (day 31 after immunization) was frequently Ig-M whereas Ig-2 and especially Ig-1 were detectable for the longest duration (992 days). After immunization with antigen in Freund's adjuvant, Ig-1 serum concentration showed the greatest increase, from almost undetectable levels to the most prominent immunoglobulin in immune serum.

Animals↗
PubMed1975

Immunological properties of Rickettsia rickettsii purified by zonal centrifugation.

The properties of Rickettsia rickettsii purified from infected chicken yolk sacs or mouse L cell cultures by sucrose density gradient centrifugation in a zonal rotor were examined in various ways. Rickettsiae derived from both L cells and yolk sacs had similar compositions: about 12% nitrogen, 1.5% phosphorus, 5% carbohydrate, and 30% fatty acids. On a dry-weight basis, purified rickettsiae were at least 2,000 times as effective as a commercial spotted fever vaccine in protecting guinea pigs against infection with spotted fever rickettsiae and mice against death from toxin of R. rickettsii. Gradient-purified rickettsiae (0.6 mug) induced a serological response in guinea pigs of the same magnitude as that stimulated by 1,600 mug of the commercial vaccine. Gradient-purified rickettsiae had little group reactivity in complement fixation tests but became anti-complementary upon storage. Microagglutination and hemagglutination tests with the purified antigen gave promise of usefulness in diagnosis of spotted fever. These results suggest that zonal centrifugation may be a valuable procedure for the preparation of R. rickettsii vaccine and diagnostic reagent.

Animals↗