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Biomedical subjects

W A Chappell

Publications and source records attributed to W A Chappell.

At least 19 recordsLinked to original sources
PubMed1986

In vitro effect of ascorbic acid on infectivity of herpesviruses and paramyxoviruses.

Suspensions of herpes simplex virus types 1 and 2, cytomegalovirus, and parainfluenzavirus type 2 were inactivated within 24 h when treated at 37 degrees C with 1 mg (5.05 mM) of copper-catalyzed sodium ascorbate per ml. The infectivity titer of respiratory syncytial virus was reduced substantially after 24 h but required 48 h for inactivation. Under these conditions, inactivation of these viruses was also successfully achieved with 5.68 mM catalyzed ascorbic acid. Copper (Cu2+), when added with the ascorbate solution at 5 micrograms/ml (0.022 mM), exhibited a catalytic effect on the inactivation of these viruses. The rate of inactivation was affected by the incubation temperature, time of exposure, and the virus concentration. Ascorbate concentrations as high as 10 mg/ml (50.5 mM) demonstrated only a minimum increase in effect on viral inactivation. The loss of infectivity did not alter either the hemagglutination or complement fixation qualities of the antigens.

Animals↗
PubMed1986

Comparison of the enzyme immunoassay, immunodiffusion, and complement fixation tests in detecting antibody in human serum to the A antigen of Blastomyces dermatitidis.

Using a new enzyme immunoassay (EIA) and standard immunodiffusion (ID) and complement fixation techniques for antibody to the A antigen of Blastomyces dermatitidis, we tested serum from 27 patients with blastomycosis diagnosed histopathologically or by culture; 20 with diagnoses made during 1981 through 1983 (Group A) and 7 during 1974 through 1976 (Group B). We also studied 30 control subjects with Mycoplasma pneumoniae infection (17 subjects), histoplasmosis (6 subjects), coccidioidomycosis (1 subject) and no known disease (6 subjects). Detectable antibody by all 3 tests was present more often for Group A than for Group B, possibly because of delay in testing. Enzyme immunoassay was the most sensitive test; a 1:8 or greater titer was present in acute-phase serum of all Group A patients tested, and a 1:64 or greater titer was associated with disseminated disease (p = 0.003). A positive ID was also more common in disseminated (88%) than in localized (33%) disease. Enzyme immunoassay titers of 1:16 were present in 4 control subjects, 3 with histoplasmosis. The 100% predictive values of a negative EIA and positive ID suggest that these tests are useful for serologic screening (EIA) and serologic confirmation (ID) of suspected blastomycosis, particularly in disseminated disease. Enzyme immunoassay titers of 1:32 or greater strongly support the diagnosis and titers of 1:16 or less may indicate localized disease or be nonspecific. None of the serologic tests predicted disease progression or reactivation.

Antibodies, Fungal↗
PubMed1986

Spirochetes in ticks and antibodies to Borrelia burgdorferi in white-tailed deer from Connecticut, New York State, and North Carolina.

Ticks were screened for spirochetes and serum samples from white-tailed deer (Odocoileus virginianus) were assayed for antibodies to Borrelia burgdorferi during 1983-1984. Using fluorescein isothiocyanate-labeled rabbit antibodies produced to B. burgdorferi, the etiologic agent of Lyme disease, spirochetes were detected in Ixodes dammini (10.5% of 1,193) and Dermacentor albipictus (0.6% of 157) adults from Connecticut, I. dammini nymphs (49.1% of 108) and adults (64.7% of 99) from Armonk, New York, and in I. scapularis (0.4% of 531) and Amblyomma americanum (3.5% of 173) adults from North Carolina. Infected ticks were either seeking hosts or feeding on deer during the summer and fall. Direct fluorescent antibody staining also revealed spirochetes in two larvae of I. scapularis that emerged from eggs deposited by separate females in the laboratory. Using indirect immunofluorescence tests, antibodies to B. burgdorferi were identified in white-tailed deer living in tick-infested areas of all three states. Aside from minor cross-reactivity, there was no serologic evidence of Treponema or Leptospira infections. Ixodes dammini is a primary vector of B. burgdorferi in northeastern United States, but in North Carolina, other ixodid ticks may transmit this spirochete to humans and wildlife.

Animals↗
PubMed1985

Adult respiratory distress syndrome associated with miliary tuberculosis.

Three patients with respiratory failure resulting from miliary tuberculosis had a characteristic clinical presentation that included a long history of a prominent cough, dyspnea, weight loss, tachycardia, tachypnea, pulmonary adventitious sounds, and hepatomegaly. Hematologic investigation showed a normal white cell count with marked left shift in the morphology of white cells in all three patients, and evidence of disseminated intravascular coagulation in one patient. In only one patient was the initial sputum positive for acid-fast bacilli; in the others, invasive diagnostic procedures including lumbar puncture, bone marrow trephine, and open-lung biopsy were necessary for diagnosis. Miliary tuberculosis should be suspected in patients with adult respiratory distress syndrome of unknown etiology. Simple diagnostic procedures such as sputum, bronchial brushings, and urine examination should be followed by bone marrow trephine, liver biopsy, transbronchial lung biopsy, and lumbar puncture if physical signs of meningitis are present.

Adult↗
PubMed1985

Effect of adjuvant vaccines on dengue virus type 2 immune ascitic fluid production.

In a comparison of dengue type 2 immune mouse ascitic fluid immunization schedules, a schedule in which adjuvant vaccines were not used produced neutralizing antibody titers that were specific and a mouse mortality rate that was lower, resulting in a greater yield of ascitic fluids. In the schedules in which emulsified adjuvant vaccines were used, the quality of the emulsion had little effect on antibody titer produced.

Adjuvants, Immunologic↗
PubMed1985

Spotted fever group rickettsiae in immature and adult ticks (Acari: Ixodidae) from a focus of Rocky Mountain spotted fever in Connecticut.

Immature and adult ixodid ticks were collected during 1983 and 1984 in Newtown, Connecticut, an area endemic for Rocky Mountain spotted fever (RMSF), to determine prevalence of infection by spotted fever group (SFG) rickettsiae. Direct fluorescent-antibody (FA) staining revealed SFG organisms in 6 (1.8%) of 332 Dermacentor variabilis larvae, 5 (7.8%) of 64 D. variabilis nymphs, and in 2 (40%) of 5 Ixodes cookei nymphs removed from small- and medium-sized mammals. Hemolymph tests detected rickettsia-like organisms in 15 (8.8%) of 170 D. variabilis adults; 8 specimens retested by direct FA were negative. In contrast, hemocytes from 5 (8.6%) of 58 Ixodes texanus females contained organisms that stained positively in both hemolymph and direct FA tests. An indirect microimmunofluorescence test identified specific antibodies to Rickettsia rickettsii, the etiologic agent of RMSF, in serum samples from a chipmunk, raccoons, and white-footed mice. Results indicate that immature or adult ticks of at least three species may be involved in the maintenance and transmission of SFG rickettsiae at Newtown.

Animals↗
PubMed1984

Comparison of an indirect fluorescent-antibody test with an enzyme-linked immunosorbent assay for serological studies of Lyme disease.

An enzyme-linked immunosorbent assay was compared with an indirect fluorescent antibody test for its ability to detect antibodies to the Lyme disease spirochete in sera of naturally infected humans, dogs, and white-footed mice and experimentally infected Swiss mice. Ninety-five percent of the total 123 sera analyzed reacted similarly in both tests. For 36 human sera, the correlation coefficient (r = 0.47) for logarithmic transformations of indirect fluorescent antibody and enzyme-linked immunosorbent assay titers was significant at P less than 0.01. Within each mammalian species, mean titers for indirect fluorescent antibody and enzyme-linked immunosorbent assay antibodies were within three-fold. Comparisons of different naturally infected mammals revealed relatively higher average titration endpoints in both tests for patients with Lyme disease. Human sera also had the widest range of titers. Both methods proved satisfactory for serological confirmation of prior spirochetal infections.

Animals↗
PubMed1984

Antibodies to Rickettsia rickettsii in Peromyscus leucopus from a focus of Rocky Mountain spotted fever in Connecticut.

During 1980-1982, white-footed mice (Peromyscus leucopus) were captured in Newtown, Connecticut, an area where Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever, is thought to be enzootic. An indirect microimmunofluorescence test identified specific antibodies to this organism in 16 of 237 (7%) sera: titration end points for 14 samples were relatively high (1:128-1:2048). Antibodies were detected in mice during 1980 and 1981 with monthly prevalences varying from 8 to 22%. These results suggest that P. leucopus may be involved in the ecology of R. rickettsii and that these rodents can be included along with other mammals to monitor spotted fever rickettsial infections in nature.

Animals↗
PubMed1984

Antibodies to spirochetes in white-tailed deer and prevalence of infected ticks from foci of Lyme disease in Connecticut.

White-tailed deer (Odocoileus virginianus) were examined for the tick, Ixodes dammini, and sera were analyzed for antibodies to spirochetes during 1982. Of the 323 animals inspected in four areas endemic for Lyme disease, 188 (58%) had adult ticks; parasitism ranged from 43% at Haddam to 82% at East Lyme. Direct and indirect fluorescent antibody tests detected spirochetes in 18 of 133 (14%) ticks. Indirect immunofluorescence tests revealed antibodies at titers of 1:64-1:4,096 to this bacterium in 93 (28%) of the 332 sera assayed. There is a close correlation among the distribution of spirochete-infected I. dammini, deer with antibodies, and human cases of Lyme disease.

Animals↗
PubMed1983

Scorpion sting producing severe muscular paralysis. A case report.

A case of scorpion (Parabuthus species) envenomation causing severe respiratory failure is presented. Systemic effects, which included muscular weakness, hypertonus and bulbar dysfunction, developed 8 hours after poisoning; this emphasizes the importance of close observation of victims of envenomation. Treatment included the administration of scorpion antivenom (SAIMR) and mechanical ventilation for 4 days.

Adolescent↗
PubMed1982

Anaesthesia and the elderly.

The peri-operative management of elderly patients presents a variety of problems to the anaesthetist. These include organ dysfunction associated with the ageing process and the high incidence of serious disease affecting major organ systems. In addition, elderly patients commonly require multiple drug therapy. As such they are likely to suffer adverse drug effects and interactions, events more liable to occur in these patients as a result of both pharmacokinetic and pharmacodynamic factors. Occasionally serious interactions may occur with drugs used during anaesthesia. The importance of adequate pre-operative assessment and preparation cannot be overemphasized, as well as the need for a team approach to the management.

Aged↗
PubMed1982

Inactivation of rabies virus in reagents used for the fluorescent rabies antibody test.

Procedures for inactivating rabies virus in reagents used for the fluorescent rabies antibody test are described. Mouse brain adsorbing suspensions containing greater than or equal to 10(9) 50% lethal doses of virus per ml were rendered noninfectious by treatment with 0.1% beta-propiolactone or by heating at 56 degrees for greater than or equal to 30 min. Viable virus in tissue impression smears was inactivated by acetone fixation at 50 degrees C for greater than or equal to 30 min or by immersion in 0.1% beta-propiolactone at 37 degrees C for 2 h. Inactivated reagents gave specific and sensitive reactions in the fluorescent rabies antibody test.

Acetone↗
PubMed1980

Anaesthesia for surgical correction of fractured femoral neck. A comparison of three techniques.

Sixty patients with fractured neck of femur and scheduled for surgical correction were randomly allocated to receive one of three anaesthetic techniques: general anaesthesia; spinal analgesia; psoas compartment block. The patients in the local anaesthetic groups also received a light general anaesthetic. There was little difference in the pre-, intra- and postoperative events, and no difference in postoperative mortality.

Aged↗
PubMed1980

Development and characterization of high-titered, group-specific fluorescent-antibody reagents for direct identification of rickettsiae in clinical specimens.

Rabbits were inoculated with purified antigen preparations of Coxiella burnetii and representative species of the spotted fever and typhus groups of rickettsiae. Their antibody responses were monitored by complement fixation tests; high-titered antisera were fractionated with ammonium sulfate and then labeled with fluorescein isothiocyanate by the dialysis method. The conjugates had homologous 3+ staining titers of 1:256 to 1:2,048 and did not exhibit nonspecific staining. The Rickettsia rickettsii, R. conorii, and R. akari conjugates reacted only with rickettsiae of the spotted fever group; the R. canada, R. prowazekii, and R. typhi conjugates were specific for the typhus group rickettsiae; and the C. burnetii conjugate stained only homologous organisms. One of these conjugates (R. rickettsii) is currently being used to identify rickettsiae in clinical specimens and has already proven its value as a diagnostic tool.

Animals↗
PubMed1980

Inactivation of rabies diagnostic reagents by gamma radiation.

Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

Animals↗
PubMed1978

Maternal blood gas status of four racial groups in late pregnancy A preliminary study.

The blood gas/acid-base status of normal healthy Black, Indian, Coloured and White pregnant women was measured. All groups exhibited evidence of hyperventilation (decreased) PaCO2 relative to the non-pregnant state, with compensatory metabolic adjustment. Arterial oxygen tensions (PaO2) were significantly lower in the Black and Indian groups compared with their White counterparts (P less than 0,01). Differences between the former two series and the Coloured group, however, just failed to reach statistically significant levels (0,1 less than P less than 0,05). The possible causes of a lowered PaO2 during pregnancy and their relevance to obstetric anaesthesia are discussed. A further study using a more sophisticated protocol is planned in an attempt to delineate the causes of these important differences.

Acid-Base Equilibrium↗