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Biomedical subjects

S McConnell

Publications and source records attributed to S McConnell.

At least 55 records · Page 3Linked to original sources
PubMed1987

Analysis of mixed infection of sheep with bluetongue virus serotypes 10 and 17: evidence for genetic reassortment in the vertebrate host.

Two seronegative sheep were infected intravenously with 10(9) PFU each of bluetongue virus (BTV) serotype 10 and BTV serotype 17. One animal experienced a mild bluetongue-like disease, and both experienced a short-duration viremia and developed neutralizing immune responses to both virus serotypes. Progeny virus was isolated from venous blood from each animal by using conditions in which reassortment could not have occurred during isolation. Electropherotypes were determined for the progeny viruses from the infected sheep, yielding strikingly similar results for the two animals. In both sheep, serotype 10 dominated among the progeny, accounting for 92% of the progeny. Serotype 17 was rarely isolated and accounted for 3% of the progeny analyzed. The remaining 5% of the progeny clones were reassortant and derived genome segments from both serotypes 10 and 17. Analysis of the parental origin of genome segments in the small number of reassortant progeny analyzed suggested that selection of specific genome segments may have occurred in the infected sheep. These data indicate that reassortment of genome segments occurs, at low frequency, in sheep mixedly infected with BTV.

Animals↗
PubMed1986

Induction of thymidine kinase activity by viruses with group B DNA genomes: bovine cytomegalovirus (bovine herpesvirus 4).

The bovine herpesvirus type 4 (BHV-4) group has a slow replication cycle, a narrow host range, and cytopathogenic effects characteristic of cytomegaloviruses (CMV), but a Group B genome structure similar to that of lymphotropic Herpesvirus saimiri (HVS). Reference BHV-4 strain DN599 and BHV-4 strains N124 and FHV-2 induced in the cytosol fraction of thymidine kinase-negative (TK-) rabbit skin (RAB-BU) cell mutants a novel TK activity. The BHV-4-induced thymidine kinase (TK) differed from the principal cytosol TK of mock-infected cells in PAGE mobility (Rm) under non-denaturing conditions and in the capacity to efficiently substitute CTP for ATP as a phosphate donor. The BHV-4 thymidine phosphorylating activity could also be distinguished from many common herpesvirus-induced TKs because it lacked iododeoxycytidine phosphorylating activity. Iododeoxyuridine, trifluorothymidine and bromovinyldeoxyuridine inhibited [3H]thymidine (0.01 mM) phosphorylation by the BHV-4 enzyme in a dose-dependent manner, but arabinosylthymine and 2'-fluoro-5-methyl-arabinosyluracil (FMAU) were poor inhibitors of [3H]thymidine phosphorylation, and acyclovir and (dihydroxy-2-propoxymethyl)guanine (DHPG) did not inhibit at all at 60 and 40 times the concentrations of [3H]thymidine, respectively.

Animals↗
PubMed1986

Intramuscular and intravaginal vaccination of pregnant cows with thymidine kinase-negative, temperature-resistant infectious bovine rhinotracheitis virus (bovine herpes virus 1).

To test the safety and efficacy of a thymidine kinase-negative (TK-), temperature-resistant (TR) mutant of bovine herpes virus-1 (BHV-1) in pregnant cows, seronegative cows, 2-5 months pregnant, were vaccinated intramuscularly (i.m.) or intravaginally (i.vag.) with this candidate vaccine virus. I.m. vaccinated cows did not shed virus i.vag. or intranasally (i.n.), but i.vag. vaccinated cows replicated virus i.vag. for 8-9 days postvaccination (p.v.) Some of the cows were challenge exposed i.n. at 46 days p.v. with virulent TK+ BHV-1(Cooper). Vaccinated cows showed no clinical disease signs p.v. or postchallenge and responded anamnestically postchallenge. All cows delivered live calves. Pre-colostrum sera of the calves were negative for BHV-1 antibodies.

Animals↗
PubMed1985

Thymidine kinase-negative bovine herpesvirus type 1 mutant is stable and highly attenuated in calves.

Calves were vaccinated intranasally (IN) or intravenously (IV) with a thymidine kinase-negative (tk-) BHV-1 mutant. Vaccinated calves developed neutralizing antibodies but did not show clinical signs of infectious bovine rhinotracheitis (IBR). Vaccination also prevented clinical signs of IBR disease following IN challenge exposure of the calves to parental Los Angeles (LA) and USDA Cooper strains of tk+ BHV-1. Nasal swabs were collected for 10 days after the vaccination and the challenge exposures to monitor BHV-1 multiplication. At both 91 and 121 days post vaccination (PV), calves were also stressed for 5 days with dexamethasone (DEX) to induce reactivation of BHV-1 and nasal swabs were obtained. tk- BHV-1 multiplied in the nasal mucosa of IN vaccinated calves and was also recovered after DEX treatment. Likewise, tk- BHV-1 was isolated from the buffy coat fraction of IV vaccinated calves, but not from nasal swabs. tk- BHV-1 vaccination reduced the multiplication of tk+ BHV-1 in the nasal mucosa, but did not completely prevent development of a persistent infection by the challenge virus. The phenotypes of viruses isolated from the nasal swabs and buffy coats were analyzed by enzyme assays of extracts from virus-infected cells and by plaque autoradiography. These assays showed that tk- BHV-1 can persist for at least 3 months in vaccinated calves and may also be transmitted from vaccinated to control calves without reverting in vivo to tk+. The results demonstrate that the tk- BHV mutant is attenuated and efficacious as a vaccine.

Animals↗
PubMed1985

An electron microscopic study of blood cells from calves experimentally infected with bluetongue virus.

Cellular elements from blood samples of calves experimentally inoculated with a quadrivalent mixture of bluetongue virus (BTV) types 10, 11, 13 and 17 were examined by transmission electron microscopy (TEM). Virus-like particles were observed within cytoplasmic vacuoles of infected agranular leukocytes from inoculated calves on postinoculation day (PID) 14. No virus-like particles were seen associated with other cellular blood elements nor were they observed in blood samples obtained prior to virus inoculation. The intravacuolar viral particles were 60nm in diameter, had a cockleburr appearance and lacked the outer polypeptide coats of mature virions. Increased cytoplasmic vacuolation was the most noticeable change in the infected cells. BTV infection was confirmed by viral isolation and serological testing. Pyrexia was the only consistent clinical sign seen in the viremic calves.

Animals↗
PubMed1985

Genome RNAS of virulent and attenuated strains of bluetongue virus serotypes 10, 11, 13 and 17.

An improved system was developed for the electrophoretic resolution of bluetongue virus (BTV) genome segments. This procedure was used to compare the genome segments of wild type (W) and vaccine (V) strains of BTV serotypes 10, 11, 13 and 17. Numerous alterations in the migration of individual genome segments could be detected between W and V strains of each serotype, suggesting that many mutations had occurred during attenuation of the V strains. In addition, electrophoretic polymorphisms not previously detected, were found between W strains of the 4 serotypes.

Bluetongue virus↗
PubMed1985

Growth characteristics of virulent and attenuated strains of bluetongue virus serotypes 10, 11, 13 and 17.

The growth properties of wild type (WT) and live, attenuated vaccine (V) strains of bluetongue virus (BTV) serotypes 10, 11, 13 and 17 were compared. All BTV strains produced maximal yields when grown at 34 C and harvested 24-36 hr after infection. The 4 V strains were temperature-sensitive (ts) for growth at 39 C as compared to the corresponding WT strains. The 4 V strains were ts for plaque formation when 37 C was used as the nonpermissive temperature. One-step growth curves showed that only the V strain of type 13 had significantly altered growth kinetics as compared to the corresponding WT. All BTV strains were strongly cell associated throughout the growth cycle.

Animals↗
PubMed1985

Use of a quadrivalent modified-live bluetongue virus vaccine in wildlife species.

Three hundred and twenty-seven animals comprised of deer, mouflon sheep and bighorn sheep were vaccinated with an experimental quadrivalent, modified-live, bluetongue virus (BTV) vaccine. No untoward effects due to the vaccine were noted nor were abortions observed in vaccinated pregnant mouflon sheep. Precipitating antibodies to BTV and epizootic hemorrhagic disease (EHD) virus were identified in the serum of several animals prior to vaccination. Virus neutralizing antibodies to 3 of the 5 serotypes of BTV which exist in the US were identified in the serum of 2 peninsular bighorn sheep.

Animals↗
PubMed1985

An evaluation of rheumatology education at Canadian medical schools.

The present study uses data from a nationally administered multiple choice examination (MCE) to assess the performance of Canadian medical students in rheumatology. An average of 1722 medical students undertook to write the Medical Council of Canada (MCC) examination each year between 1978-82. Between 17 and 29 of the 516 MCE questions were of a rheumatological nature and the success rate of students from the 16 Canadian medical schools varied between 65.5 and 78.5% in any given year. No direct correlation was noted between the students' MCE performance and the amount of rheumatology education given at an individual university. Analysis of Arthritis Society Undergraduate Statistics indicated that the average medical student in Canada receives 17.5 h of didactic lectures, 10.4 h of clinical bedside demonstration and 8.9 h of direct supervision of rheumatologic patients by rheumatologists.

Canada↗
PubMed1984

A situational analysis of adolescent smoking.

Forty-four adolescent smokers self-monitored their smoking for 1 week. Four 4 hr each day subjects recorded the person, place, and activity associated with each cigarette smoked. Seventy-one percent of all cigarettes were smoked in the presence of another person. Roughly half of those cigarettes were were smoked with peers. A surprising amount of smoking occurred in the subject's own home, suggesting that the smoking of the subjects is accepted, if not condoned , by their parents. The data generally confirm the social nature of adolescent smoking.

Adolescent↗
PubMed1984

Adolescents' compliance with self-monitoring and physiological assessment of smoking in natural environments.

Brief daily telephone calls were evaluated as a method of enhancing adolescents' compliance with self-monitoring and physiological assessments of cigarette smoking in the natural environment. Seven direct and indirect measures of compliance were devised. Results indicated that subjects receiving telephone calls complied significantly more than control subjects in providing saliva samples and recording detailed self-monitoring data.

Adolescent↗
PubMed1983

Immunodiffusion test antigen from bluetongue virus-infected newborn mouse brains.

Three methods of extracting bluetongue virus (BTV)-infected newborn mouse brains to prepare immunodiffusion (ID) test antigen were used. The most readily readable and reproducible results were obtained with fluorocarbon-extracted brains homogenized in 8.5% sucrose. Mouse brain- and reference cell culture-derived antigens gave a line of identity with anti-BTV serum. Extracts of noninfected brains were nonreactive. ID tests on field-collected bovine sera, comparing the two types of antigen, resulted in only 73% agreement due to a greater sensitivity of cell culture-derived antigen. A 70.5% agreement resulted when comparing mouse brain-derived antigen in ID tests with complement fixation tests, the latter being least sensitive. ID test results with sera from experimental sheep gave 95.9% agreement between cell culture- and mouse brain-derived antigens. Between ID, which detects antibody to the BTV common or group antigen, and virus neutralization, which detects type-specific antibody, the agreement was 71.4% with postchallenge sera. Data from pre- and postinjection sera, however, indicate the possible activity in Texas of viruses other than International BTV Types 10, 11, 13, and 17.

Animals↗
PubMed1983

Apparent displacement with a monocular prism differs from optical displacement.

This experiment showed that phoria-induced displacement adds to or subtracts from prism-induced displacement. A near stimulus (25 cm) was apparently displaced more than the optical displacement when the base of a prism was out and less when the base was in. In contrast, a far stimulus (200 cm) was displaced less when the base was out and more when the base was in. Moreover, the between-subjects variability of the apparent displacement was greater with monocular than with binocular viewing. Some implications for studies on monocular prism adaptation are discussed.

Adaptation, Ocular↗
PubMed1983

Experimental bluetongue infections in gnotobiotic lambs and kids.

Ten gnotobiotic lambs and 4 gnotobiotic kids inoculated with virulent bluetongue virus (BTV) including BTV international types 10, 11, 13, and 17 did not show clinical signs of bluetongue. Seroconversion was observed in all gnotobiotes and conventional control sheep inoculated with the appropriate challenge BTV. Viremia was detected in 1 BTV-infected gnotobiote. Conventional control sheep inoculated with a given BTV international serotype showed a marked febrile response with hyperemia of the nasal and buccal mucosa.

Animals↗
PubMed1982

Increased incidence of bovine papular stomatitis in neonatal calves.

A high incidence of bovine papular stomatitis (BPS) occurred in neonatal calves following neonatal thymectomy and antilymphocyte globulin treatment, sham thymectomy, treatment with normal horse globulin and in untreated calves. The source of BPS virus was not identified but was suspected to be latent in the calves and activated by thymectomy although no experimental evidence directly supported this conclusion. The potential for activation of a latent BPS infection was indicated by an apparent relationship between the stress of surgery or foreign protein inoculation and the severity of lesions. Subsequent bovine viral diarrhea virus infection did not result in recrudescence.

Animals↗