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Biomedical subjects

T Bryan

Publications and source records attributed to T Bryan.

28 records · Page 2Linked to original sources

Learning disabled children's syntactic proficiency on a communicative task.

Previous studies have generally examined learning disabled children's syntactic ability either on structured tasks or by analyzing oral language samples collected under conditions not typical of natural communicative settings. Thus, these studies are of limited value in exploring the impact of learning disabled children's deficits in linguistic structure on their use of language in social contexts. The purpose of this study was to investigate learning disabled children's syntactic proficiency during a task requiring them to convey information to a listener. Subjects were selected on the bases of teacher ratings, reading achievement scores, and Peabody Picture Vocabulary Test IQ scores within the normal range; those children identified as learning disabled received low ratings and demonstrated underachievement (below 40th percentile for their grade) in reading. Oral language samples were collected by having learning disabled and normally achieving children in grades two, four, six, and eight participate in a referential communication task in which they described abstract shapes to an experimenter. The length and syntactic complexity of the children's descriptions were assessed. Learning disabled children in all grades were found to produce shorter mean t-units and shorter mean main clauses than nondisabled children even on this relatively simple communicative task. Although learning disabled children's linguistic problems have previously been characterized as subtle, these findings suggest that their productive language deficits may be significant enough to interfere with even the informal and elliptical conversations characteristic of communication among peers and family members.

Adolescent

Identification and cloning of endogenous retroviral sequences present in human DNA.

Using nonstringent annealing conditions and a 2.75-kilobase segment of cloned African green monkey DNA that specifically hybridizes to the proviruses of AKR ecotropic murine leukemia virus (MuLV) and baboon endogenous virus (BaEV) as a probe, we detected related sequences in three different preparations of human brain DNA fragments. The blot-hybridization pattern obtained with cleaved human DNA was similar to that previously reported for the interaction of MuLV cDNA and cleaved mouse DNA and suggested the presence of numerous copies of retrovirus-related sequences in the human genome. The labeled 2.75-kilobase fragment derived from cloned monkey DNA was used to screen a human DNA library in Charon 4A. One clone obtained hybridized to three contiguous MuLV-and BaEV-reactive fragments of the cloned monkey DNA and to multiple fragments of human DNA including a prominent 1.0-kilobase EcoRI fragment also present in the clone.

Animals

Detection and cloning of murine leukemia virus-related sequences from African green monkey liver DNA.

By using low-stringency nucleic acid hybridization conditions and specific subgenomic segments of the AKR ecotropic provirus as probes, murine leukemia virus (MuLV)-related sequences were detected in African green monkey (AGM) liver DNA. The MuLV-reactive segments present in restricted AGM DNA ranged from 1.9 kilobases (kb) to greater than 10 kb in size. On the basis of this finding, a 17-kb segment was cloned from a partial EcoRI AGM library in lambda Charon 4A which shared nearly 5 kb of homology with AKR ecotropic MuLV DNA. The MuLV-related sequences detected in restricted preparations of AGM DNA or present in the cloned monkey DNA reacted with probes mapping 2.0 to 7.0 kb from the 5' terminus of the AKR ecotropic provirus. The AGM clone also contained repeated sequences that flanked the MuLV-related segment. Labeled, subgenomic, MuLV-reactive segments of the monkey clone hybridized to multiple restriction fragments of AGM liver DNA, indicating the presence of several copies of the MuLV-related sequences.

Animals

Identification of ecotropic proviral sequences in inbred mouse strains with a cloned subgenomic DNA fragment.

A specific probe for detecting ecotropic murine leukemia virus sequences was constructed by cloning a 500-base-pair DNA segment, corresponding to a portion of the env region of the AKR ecotropic virus, in a pBR322/Escherichia coli K-12 host/vector system. This probe was used to screen the cellular DNAs of six inbred strains of mice for the presence of ecotropic retroviral DNA sequences by the Southern blot hybridization procedure. Three copies of ecotropic viral DNA were detected in AKR/N (a high-ecotropic virus strain) and two were found in BALB/c (a low-ecotropic virus strain) DNAs. As expected, no sequences reactive with this probe were found in NFS mouse DNA (a virus-negative strain). However, cellular DNA sequences that reacted strongly with the ecotropic-specific DNA probe were detected in certain NZB, C57L, and 129 mice (all virus-negative strains). In contrast to the reactive sequences in AKR and BALB/c, the reactions were chiefly associated with EcoRI segments that were subgenomic in size.

Animals

Productive infection of Bacillus subtilis 168, with bacteriophage SP-10, dependent upon inducing treatments.

Strains of Bacillus that harbor defective phage PBSX were found to be insensitive to SP-10(C), although the phage adsorbed to these insensitive strains. Strains that did not carry the phage were sensitive to SP-10(C). B. subtilis 168 ind(-), which can be tranduced by SP-10(C) but is nonpermissive for the phage, was rendered phage-sensitive after treatment with ultraviolet (UV) light or mitomycin C. After induction with UV light, maximal sensitivity to SP-10(C) was obtained at a multiplicity of infection (MOI) of approximately 14; with mitomycin C induction, an MOI of approximately 1.0 was required. Phage maturation in sensitized cells was followed by plating infected streptomycin-sensitive cells in the presence of streptomycin at various stages during phase development. The latent period was estimated at 60 to 75 min. We suggest that the resistance of B. subtilis 168 to SP-10 is controlled, at least in part, by the presence of a defective prophage.

Bacillus subtilis

Conformity to peer pressure by students with learning disabilities: a replication.

This study assessed the reported responses of junior high school students with learning disabilities and normally achieving classmates to peer pressure to conform in prosocial and antisocial activities. The results replicate those of an earlier study in finding that students with learning disabilities indicated more willingness than their classmates to conform to peer pressure to engage in antisocial actions.

Achievement

The influence of affect on the achievement and behavior of students with learning disabilities.

Research indicates that students with learning disabilities are likely to be at greater risk for experiencing negative affect than their higher achieving counterparts. The purpose of this article is to review recent research on the effects of affect on thoughts, cognition, and behavior. This research finds that induced positive affects leads to more accurate performance on math, greater learning of new vocabulary, and better performance on a new learning task. Implications of and suggestions for follow-up studies of negative and positive affect in students with learning disabilities are presented.

Adolescent

The influence of affect on social-information processing.

This study examined the impact of four affect induction conditions (self-induced positive affect, music-induced positive affect, music-induced negative affect, and neutral affect) on the social-information-processing skills of 96 seventh-grade students with and without learning disabilities using the Dodge (1983) model of social skills. Following a 1-minute affect induction, students were presented with a social problem and asked a series of questions that tested their social skills. Although the results did not find significant differences between school-identified students with and without learning disabilities, there were significant main effects for language skills and affect induction. Students above the median on the Iowa Test of Basic Skills language test generated more solutions and fewer negative responses than students below the median. Students in the self-induced positive affect condition generated more solutions, whereas students in the music-induced positive affect condition generated more embellishments and perceived less interpretation (negative/positive), than students in the neutral and negative affect conditions. The implications of these results for research and practice are discussed.

Adolescent