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Biomedical subjects

J A Sherman

Publications and source records attributed to J A Sherman.

At least 19 recordsLinked to original sources
PubMed1995

The traY gene product and integration host factor stimulate Escherichia coli DNA helicase I-catalyzed nicking at the F plasmid oriT.

F plasmid conjugative transfer is initiated by the introduction of a site- and strand-specific nick within the plasmid origin of transfer (oriT). Genetic studies have shown nick formation to be dependent on both the traI and traY genes. However, highly purified TraIp, the traI gene product, nicks oriT in a site- and strand-specific manner in the absence of the traY gene product (TraYp) in vitro (Matson, S.W., and Morton, B.S. (1991) J. Biol. Chem. 266, 16232-16237). Analysis of the oriT region has revealed binding sites for TraYp and the host protein integration host factor (IHF). To explore possible interactions occurring at oriT, highly purified TraIp, TraYp, and IHF were incubated with a supercoiled oriT-containing DNA substrate. A marked enhancement of the nicking reaction catalyzed by TraIp was observed in a reaction that required both TraYp and IHF. In addition, TraIp was able to nick a linear oriT-containing double-stranded DNA substrate when IHF and TraYp were present in the reaction; such a substrate is not nicked by TraIp alone. Individual protein concentration requirements for the supercoiled and linear nicking reactions were similar, and the reactions occurred at equal velocity, suggesting that they are biochemically identical. Concentrations of TraYp and IHF that yield half-maximal activity in the nicking assays compare well with the reported KD values for the IHF and TraYp binding sites in oriT. These data, coupled with data presented in the accompanying report, suggest that TraYp and IHF bind independent of one another, forming a nucleo-protein complex with oriT that can be recognized and nicked by TraIp.

Bacterial Proteins↗
PubMed1994

Escherichia coli DNA helicase I catalyzes a sequence-specific cleavage/ligation reaction at the F plasmid origin of transfer.

Recent studies have shown that the Escherichia coli F plasmid-encoded traI gene product (TraIp), also known as DNA helicase I, catalyzes the formation of the site- and strand-specific nick that initiates F plasmid DNA transfer. Scission of the phosphodiester bond at the nic site within the origin of transfer (oriT) is accompanied by the covalent attachment of TraIp to the 5'-phosphate of the nicked DNA strand. This mechanism suggests that TraIp may also be capable of catalyzing a DNA ligation reaction using the energy stored in the protein-DNA intermediate. To test this possibility, an in vitro assay was designed that utilized short single-stranded DNA oligonucleotides of different lengths derived from the region within oriT that spanned the nic site. Purified TraIp was capable of efficiently cleaving single-stranded DNA that contained a nic site, and upon cleavage, the protein became covalently linked to the 5'-end of the nic site. When TraIp was incubated with two oligonucleotides of different length that contained the nic site, there was formation of novel recombinant products resulting from a TraIp-catalyzed cleavage/ligation reaction. Furthermore, the cleavage and ligation reactions were both sequence-specific. These data suggest that TraIp plays an important role in the initiation and termination of conjugative DNA transfer.

Base Sequence↗
PubMed1993

Choice and control. New opportunities for people with developmental disabilities.

Over the past few years, people with developmental disabilities have had an increasing number of opportunities to make choices and have control over their lives. There has also been a considerable amount of experimental research conducted on the effects of providing opportunities to make choices or to exercise control. The results of this research strongly suggest that providing opportunities for choice and control over events can affect the degree to which people participate in activities, the types of behaviors displayed during the participation, and people's perceptions about the situation. This article reviews this experimental research, discusses traditional views and current perspectives regarding choice and control for people with developmental disabilities, and presents ways of increasing the amount of choice and control available to people with developmental disabilities.

Child↗
PubMed1992

Social validation of component behaviors of following instructions, accepting criticism, and negotiating.

This study evaluated whether behaviors often taught as part of social skills training are judged favorably by others. Community judges evaluated the performances of people in various situations requiring one of three social skills: following instructions, accepting criticism, and negotiating to resolve conflicts. These skills were displayed in videotaped scenes by actors with and without mental retardation who acted out roles that had different types of authority relationships, and when different components or clusters of behavior (nonverbal, specific verbal, or general verbal behaviors) were performed well or poorly. The highest ratings by judges were of videotaped scenes that depicted correct use of all behaviors, regardless of which skill was being examined, whether or not the actor had mental retardation, or what the relationship was between the two actors. The lowest ratings were of videotaped scenes that depicted poor performance of all behaviors, and intermediate ratings were obtained when only some of the behaviors were performed poorly. These results, as well as the verbal responses of judges to questions, indicated that the different behaviors commonly used in teaching the skills of following instructions, accepting criticism, and negotiating are relevant to judgment of social performance, and are likely to be reinforced and maintained by social contingencies.

Activities of Daily Living↗
PubMed1992

Ongoing consultation as a method of improving performance of staff members in a group home.

A model of ongoing consultation was implemented in a community group home for 8 adults with severe and profound mental retardation. Two consultants, highly experienced in working with people with mental retardation and in the procedures used in group homes, taught staff members to use a token reinforcement system, to engage the adults in a variety of activities, and to improve the content and style of the staff members' interactions with the adults. The consultants taught skills to 9 staff members through brief mini-workshops, direct observation of the staff members' use of the skills during regular activities in the group home, and individual verbal feedback regarding a staff member's performance of the skills. Evaluation of the ongoing consultation process by the 2 consultants showed it to be effective in improving the performance of the staff members and in changing the behaviors of the adults who lived in the home. Continued implementation of the process, however, appeared to be necessary for the behavior changes of staff members to be maintained at high levels.

Adolescent↗
PubMed1992

Social evaluation of behaviors comprising three social skills and a comparison of the performance of people with and without mental retardation.

We evaluated whether behaviors commonly taught to persons with mental retardation as part of three important social skills (following instructions, accepting criticism, and negotiating to resolve conflicts) were responded to favorably by other people. People with mental retardation who lived in the community and other people from the community participated in videotaped role plays involving each of the social skills. The performances of participants were scored according to behavioral checklists. Participants with mental retardation scored as well as other participants on following instructions and accepting criticism but lower on negotiating. Community members were asked to evaluate how well the participants did in the videotaped role-play situations. There were high positive correlations between the scores derived from the behavioral checklists and the evaluations of community members for both groups of participants.

Adolescent↗
PubMed1991

Teaching adults with severe and profound retardation to exit their homes upon hearing the fire alarm.

Prompting, modeling, and differential reinforcement with client-chosen rewards were used to teach 3 nonverbal people with severe to profound mental retardation to exit their group homes at the sound of the house fire alarm, using a multiple baseline design. All 3 participants learned to exit independently in less than 2 min in all experimenter-initiated surprise fire drills and in the majority of staff-initiated surprise fire drills. Each participant was also able to exit from five areas of the house from which teaching was not done.

Adult↗
PubMed1991

In-home generalization of social interactions in families of adolescents with behavior problems.

The effects of a three-phase family communication program were evaluated. In the skill-teaching phase, family members were taught reciprocal social communication skills in a clinic setting. During the skill-review phase, each family member practiced the skills in their homes with the teacher. During the home-based family conference phase, each family was taught to use a structured format to resolve current family issues using their newly acquired skills. In-home parent-youth interactions were observed during a series of 1-hr sessions that involved directed and nondirected situations. Evaluation included a multiple baseline design across skills during the skill-teaching phase and a multiple baseline design across families for the family conference phase. Although the procedures of the skill-teaching phase resulted in parent-adolescent dyads learning to use the skills in the teaching setting, competent use of the skills in the home was not observed until the family conference phase was implemented. These results suggest the importance of home-based intervention if changes are to be obtained at home.

Adolescent↗
PubMed1990

Teaching autistic and severely handicapped children to recruit praise: acquisition and generalization.

Autistic and severely handicapped children were taught to ask questions (e.g., "How did I do?") and make requests (e.g., "Check it out") to recruit or set the occasion for praise from an adult. Teaching occurred during structured sessions in a community-based group home. Generalization of the children's use of these behaviors was evaluated during other activities in the teaching area, with other staff members in different areas of the home, and at each child's academic classroom. The children learned the behaviors to cue or set the occasion for praise independently and used these behaviors in all of the generalization settings. In the generalizations settings, the children were frequently successful in recruiting praise.

Adolescent↗
PubMed1990

Balancing the right to habilitation with the right to personal liberties: the rights of people with developmental disabilities to eat too many doughnuts and take a nap.

In the pursuit of efficient habilitation, many service providers exercise a great deal of control over the lives of clients with developmental disabilities. For example, service providers often choose the client's habilitative goals, determine the daily schedule, and regulate access to preferred activities. This paper examines the advantages and disadvantages of allowing clients to exercise personal liberties, such as the right to choose and refuse daily activities. On one hand, poor choices on the part of the client could hinder habilitation. On the other hand, moral and legal issues arise when the client's right to choice is abridged. Recommendations are offered to protect both the right to habilitation and the freedom to choose.

Adolescent↗