Search PubMed⌕ Search

Biomedical subjects

T Bryan

Publications and source records attributed to T Bryan.

At least 19 recordsLinked to original sources
PubMed2002

Specific mucosal IgA immunity in turkey poults infected with turkey coronavirus.

The objective of this study was to elucidate the kinetics and magnitudes of specific IgA antibody responses in intestines of turkey poults infected with turkey coronavirus (TCV). Turkey poults were orally inoculated with TCV at 10 days of age. Intestinal segment cultures were administered for duodenum, jejunum, and ileum and the IgA antibody responses were analyzed at 1, 2, 3, 4, 6, or 9 weeks post-infection (PI) in two different experiments. The kinetics of virus-specific IgA antibody responses in duodenum, jejunum, and ileum were similar: gradually increased from 1 week PI, reached the peak at 3 or 4 weeks PI, and declined afterward. The virus-specific IgA antibody responses in duodenum, jejunum, and ileum showed negative correlation with duration of TCV antigen in the corresponding locations of intestine with Spearman's correlation coefficient of -0.85 (p=0.034), -0.74 (p=0.096), and -0.75 (p=0.084), respectively. Moreover, the virus-specific IgA antibody responses in serum were positively correlated with that of duodenum (coefficient=0.829, p=0.042), jejunum (coefficient=0.829, p=0.042), and ileum (coefficient=0.771, p=0.072) segment cultures, suggesting that the induction of specific IgA response in serum was predictive of an IgA response in intestine. The results indicate that intestinal mucosal IgA antibodies to TCV are elicited in turkeys following infection with TCV. The local mucosal antibodies may provide protective immunity for infected turkeys to recover from TCV infection.

Animals↗
PubMed2001

Humoral and cellular immune responses in turkey poults infected with turkey coronavirus.

The objective of the present study was to elucidate the kinetics of humoral and cellular immune responses of turkey poults infected with turkey coronavirus (TCV). Turkey poults were orally inoculated with TCV at 10 d of age, and the immune responses were analyzed at 1, 3, 7, 14, 21, 28, 42, and 63 d postinfection (PI) in three different experiments. Total Ig to TCV was initially detected at 7 and 14 d PI in Experiments 1 and 3. In addition, Ig gradually increased from 7 to 21 d PI and remained at 80 immunofluroescent antibody assay (IFA) titers or more thereafter. Lymphocyte proliferation responses of spleen cells to concanavalin A were higher in TCV-infected turkeys than in noninfected control turkeys with significant differences (P < 0.05) being noted at 14 and 63 d PI in Experiment 2 and at 3 and 28 d PI in Experiment 3. Strong IFA staining response to TCV antigen was observed in intestines of turkeys at 1, 3, and 7 d PI, and the response declined from 14 to 28 d PI in Experiment 3. In Experiment 3, the IgG isotype antibody response to TCV was markedly increased after 21 d PI and remained high until 63 d PI. The IgM isotype antibody response to TCV was 1.40 and 0.91 at 7 and 14 d PI, respectively. The IgA isotype antibody response to TCV was very low as detected at 7 (0.13), 14 (0.20), and 21 (0.17) d PI. Turkeys infected with TCV had significantly higher (P < 0.05) antibody response to sheep erythrocytes than noninfected controls at 7 d PI. Virus-specific lymphocyte proliferation response of spleen cells was significantly stimulated (P < 0.05) at 63 d PI in Experiment 3. The proportion of the CD4+ subpopulation of T lymphocytes was significantly increased (P < 0.05) at 1, 7, and 21 d PI in Experiment 3. The results indicate that humoral and cellular immunities to TCV are elicited in turkeys following infection with TCV.

Animals↗
PubMed1999

In ovo vaccination technology.

More than 80% of the U.S. broiler industry has converted to the in ovo vaccination process for control of Marek's disease. Providing certain criteria are met, including timing and site of vaccine placement, vaccine mixing, machine sanitization, and hatchery management specifications, this has proven to be an efficacious and convenient method of vaccination. Efforts to extend the technology for other viral vaccines including Newcastle, bronchitis and bursal disease, and bacterial and parasitic vaccines are in progress. Collectively, these studies demonstrate that in ovo vaccination technology using approved vaccine is a safe, efficacious, and convenient method for vaccination of poultry.

Animals↗
PubMed1997

Telomeres in the haemopoietic system.

The limited life span of most blood cells requires the continuous production of cells, which in adults exceeds 10(12) cells/day. This impressive production of cells (approximately 4 x 10(16) cells over a lifetime) is achieved by the proliferation and differentiation of committed progenitor cells, which themselves are derived from a population of pluripotent stem cells with self-renewal potential. Paradoxically, the large majority of stem cells in adult bone marrow are quiescent cells. One possibility is that stem cells, like other somatic cells, have only a limited replicative potential (< 100 divisions). This hypothesis is supported by two key observations and the consideration that, in theory, 55 divisions can yield 4 x 10(16) cells. First, it was shown that 'candidate' stem cells purified from fetal and adult tissue showed dramatic functional differences in turn-over time and the ability to produce cells with stem cell properties, Second, these functional differences were found to correlate with a measurable loss of telomere repeats despite the presence of low but readily detectable levels of telomerase in all purified cell fractions. In order to address questions about the role of telomeres in normal and malignant haemopoiesis, we developed a quantitative fluorescence in situ hybridization technique. Here we review the characteristics of this novel tool to assess the number of telomere repeats at the end of individual chromosomes and provide an overview of recent observations.

B-Lymphocytes↗
PubMed1996

Analysis of live, oral poliovirus vaccine monopools for human immunodeficiency virus type 1 and simian immunodeficiency virus.

Although there is no evidence for transmission of mammalian retroviruses to humans via vaccine immunization, the allegations of contamination of oral poliovirus vaccines with human immunodeficiency virus (HIV) type 1 or a hypothetical progenitor virus from monkeys has created controversy and dispute regarding the origin of AIDS in humans. Twelve monovalent lots of live, attenuated oral poliovirus vaccine types 1, 2, and 3, which were released for use by a North American manufacturer between 1976-1989, were tested for the presence of HIV-1 and simian immunodeficiency virus (SIV). HIV/SIV were not detected in these monovalent poliovirus vaccine lots with the reverse transcriptase assay, a general detection assay, and highly sensitive and specific polymerase chain reaction assays.

Animals↗
PubMed1995

Teachers' ratings of the social competence and school adjustment of students with LD in elementary and junior high school.

The purpose of this study was to examine whether teachers' judgments of students' social competence and school adjustment differentiated students with learning disabilities (LD) (n = 30; boys = 19, girls = 11) from low-achieving (LA) students (n = 29; boys = 17, girls = 12) and average-achieving (AA) students (n = 33; boys = 18, girls = 15) at two grade levels: third/fourth (mean age = 9.97, SD = 1.09) and seventh/eighth (mean age = 13.63, SD = .65). Teachers completed the Walker-McConnell Scale of Social Competence and School Adjustment for each student. They rated younger students with LD and LA students as having significantly lower social competence and school adjustment than their AA peers. In addition, the results supported the use of teacher ratings for initial screening and identification of elementary students at high risk for social-behavioral problems. However, teachers' ratings did not discriminate LD, LA, and AA students at the older grade levels. The discussion focuses on the utility of teachers' identification of social problems at different grade levels.

Adolescent↗
PubMed1994

Getting caught in misconduct: conceptions of adolescents with and without learning disabilities.

This study examined adolescents' conceptions about how to respond after being caught in misconduct, in order to determine whether students with learning disabilities differ from nondisabled students in their beliefs regarding apprehension. A total of 88 students with learning disabilities (62 male, 26 female) and 84 nondisabled students (45 male, 39 female) were interviewed about 10 scenarios in which a teenager was caught by authorities after participating in misconduct, either alone or with a peer. The mean age of the students was 16 years (SD = 1.4). The results indicated that the students with learning disabilities were significantly more likely than other students to suggest escaping and less likely to suggest accepting the consequences, although the differences were not great. The implications of these findings are discussed.

Adolescent↗
PubMed1994

Doing homework: perspectives of elementary and junior high school students.

A survey of homework experiences was administered to 1,527 elementary and junior high students in regular (n = 1,242), resource (n = 234), and self-contained special education (n = 51) classrooms. The results found significant main effects for Group, Grade, and Group by Grade interactions for items related to amount of, type of, and time spent doing homework; opportunity to do homework at school; parents' assistance; students' beliefs about homework assignments and grading; and students' feelings about homework and school. The higher incidence of negative feelings and opinions from students in resource room programs suggests that students' understanding of assignments, the nature of the assignments, and the feedback given to students are important issues requiring closer evaluation. The results also suggest that changes in homework assignments and grading may make the transition from elementary to junior high school particularly difficult for students with special needs.

Adolescent↗
PubMed1992

Students' expectations about peer pressure to engage in misconduct.

Previous research suggests that students with learning disabilities may differ from other students in their expectations of how peers are likely to propose engaging in misconduct. This study followed up on these findings using a methodology that did not require the participants to produce their responses verbally. Participants were 74 students with learning disabilities (53 male, 21 female) and 85 students without disabilities (40 male, 45 female) from high schools in three types of communities (urban, primarily black; urban, primarily Hispanic; suburban, primarily white). The students were presented with a series of pairs of statements that might be made by a teenager trying to entice a peer into misconduct and were asked to indicate which statement in each pair was the more persuasive. The results partially replicated the earlier research. The methodological and social implications of these results are discussed.

Adolescent↗
PubMed1991

Biochemical and biological comparison of HIV-1 NEF and ras gene products.

Human immunodeficiency virus type 1 (HIV-1) NEF protein has been reported to share certain biochemical and structural properties with known oncoproteins like src or rats. To determine whether this is a general property of NEF from various HIV isolates, three different NEF proteins were expressed in Escherichia coli using a thermoinducible expression system previously exploited to overproduce functionally active p21 ras proteins. ras and NEF proteins expressed in this manner were evaluated in parallel to compare their biochemical and biological properties. In contrast to ras, our NEF protein preparations had no detectable GTP binding but showed autophosphorylation activity when incubated in the presence of either GTP or ATP. This putative autokinase activity was higher in NEF proteins containing threonine at position 15 than in those carrying alanine at that position. Two different NEF genes also failed to induce oncogenic transformation of permanently transfected NIH 3T3 cells under conditions that led to oncogenic transformation using activated ras genes. Also, unlike ras, the NEF gene products failed to induce meiotic maturation when injected into fully grown Xenopus oocytes.

Adenosine Triphosphate↗
PubMed1991

Positive mood and math performance.

Two studies are reported that assessed the impact of positive moods on students' feelings of self-efficacy and math performance. In the first study, 32 black and Hispanic girls and boys in the third to fifth grades, who had been identified by teachers as at risk for school failure, and a control sample of normally achieving classmates served as subjects. In the second study, 15 males and 3 females in junior high and high school attending a private school for students with learning disabilities served as subjects. In both studies, students were randomly assigned to a positive-mood induction condition or a no-treatment control condition. Following this, they completed a measure of self-efficacy for math and were then given 5 minutes to do 50 math problems. In both studies, analyses of covariance using standardized math scores as the adjustor variable found that children in the positive-mood condition completed significantly more problems accurately than children in the no-treatment control condition. In addition, in the junior high and high school sample, students in the positive-mood induction condition expressed greater self-efficacy for math than students in the control condition. The results of these two studies raise many questions about the role of affect, positive and negative, in the learning and performance of students with learning disabilities that researchers and teachers might explore.

Adolescent↗
PubMed1991

Popliteal arterial injuries associated with fractures or dislocations about the knee as a result of blunt trauma.

A total of 73 patients with popliteal arterial injuries due to blunt trauma were treated at the Los Angeles County/University of Southern California Medical Center between January 1975 and January 1986. The injuries resulted from high-energy trauma (70% were motor-vehicle-related), and were associated with a variety of fractures and dislocations about the knee. Forty-eight of the patients (66%) had open injuries, 27% of which became infected; the infection rate for all injuries was 22%. The average time from injury to anastomosis was 14.6 hours. The overall amputation rate in the series was 15%. Ten of the 11 amputations were associated with open, type III fractures. The amputation rate did not correlate with type of fracture, delay in diagnosis, or delay in surgery of up to 24 hours, but was directly related to the degree of soft-tissue trauma.

Academic Medical Centers↗
PubMed1988

Oligomeric structure of p21 ras proteins as determined by radiation inactivation.

Using radiation inactivation we determined that p21 ras proteins exhibit an oligomeric target size when assayed both structurally and functionally. Similar target sizes of p21 in ras-transformed cells and in purified preparations of the protein suggested that its structure is homo-oligomeric. p21 monomers were destroyed by radiation with the same target size as the GTP binding activity, indicating the occurrence of a tight association allowing energy transfer between the monomers. Irradiation in the presence of GTP, dithiothreitol, or EDTA did not change the target size. Normal (Gly12) and transforming (Lys12) forms of the protein exhibited similar target sizes. The homo-oligomeric structure suggests that p21 ras proteins do not conform to the structure of monomeric alpha subunits in classical G proteins (alpha beta gamma heterotrimers) and establishes similarities with other homo-oligomeric proteins (such as Escherichia coli CRP) which acquire the active conformation through subunit reorientation upon nucleotide binding.

Cell Line, Transformed↗