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Biomedical subjects

H A Becker

Publications and source records attributed to H A Becker.

13 recordsLinked to original sources
PubMed1997

Maize Activator transposase has a bipartite DNA binding domain that recognizes subterminal sequences and the terminal inverted repeats.

The mobility of maize transposable element Activator (Ac) is dependent on the 11-bp terminal inverted repeats (IRs) and approximately 250 subterminal nucleotides at each end. These sequences flank the coding region for the transposase (TPase) protein, which is required for the transposition reaction. Here we show that Ac TPase has a bipartite DNA binding domain, and recognizes the IRs and subterminal sequences in the Ac ends. TPase binds cooperatively to repetitive ACG and TCG sequences, of which 25 copies are found in the 5' and 20 copies in the 3' subterminal regions. TPase affinity is highest when these sites are flanked on the 3' side by an additional G residue (A/TCGG), which is found at 75% of binding sites. Moreover, TPase binds specifically to the Ac IRs, albeit with much lower affinity. Two mutations within the IRs that immobilize Ac abolish TPase binding completely. The basic DNA binding domain of TPase is split into two subdomains. Binding to the subterminal motifs is accomplished by the C-terminal subdomain alone, whereas recognition of the IRs requires the N-terminal subdomain in addition. Furthermore, TPase is extremely flexible in DNA binding. Two direct or inverted binding sites are bound equally well, and sites that are five to twelve bases apart are similarly well bound. The consequences of these findings for the Ac transposition reaction are discussed.

Base Sequence↗
PubMed1996

Binding sites for maize nuclear proteins in the subterminal regions of the transposable element Activator.

Genetic data suggest that transposition of the maize element Activator (Ac) is modulated by host factors. Using gel retardation and DNase I protection assays we identified maize proteins which bind to seven subterminal sites in both ends of Ac. Four DNase I-protected sites contain a GGTAAA sequence, the other three include either GATAAA or GTTAAA. The specificity of the maize protein binding to Ac was verified by using a synthetic fragment containing four GGTAAA motifs as probe and competitor in gel retardation assays. All seven binding sites are located within regions required in cis for transposition. A maize protein binding site with the same sequence has previously been identified in the terminal inverted repeats of the maize Mutator element. Thus, the protein, that recognizes this sequence is a good candidate for a regulatory host factor for Ac transposition.

Base Sequence↗
PubMed1995

The binding motifs for Ac transposase are absolutely required for excision of Ds1 in maize.

A reverse genetic system for studying excision of the transposable element Ds1 in maize plants has been established previously. In this system, the Ds1 element, as part of the genome of maize streak virus (MSV), is introduced into maize plants via agroinfection. In the presence of the Ac element, excision of Ds1 from the MSV genome results in the appearance of viral symptoms on the maize plants. Here, we used this system to study DNA sequences required in cis for excision of Ds1. The Ds1 element contains the Ac transposase binding motif AAACGG in only one of its subterminal regions (defined here as the 5' subterminal region). We showed that mutation of these motifs abolished completely the excision capacity of Ds1. This is the first direct demonstration that the transposase binding motifs are essential for excision. Mutagenesis with oligonucleotide insertions in the other (3') subterminal region resulted in elements with either a reduced or an increased excision efficiency, indicating that this subterminal region also has an important function.

Base Sequence↗
PubMed1995

Oncology education needs survey of registered nurses in Texas.

In response to the need to determine continuing education priorities in oncology nursing, the Nurse Oncology Education Program surveyed a geographically stratified random sample of Texas registered nurses concerning their oncology practices, perceived skill levels, and personal needs for training in 61 topics areas. The 378 respondents rated their skill levels low to medium, although 62% cared directly for patients with cancer. The highest-rated priorities for professional education were: legal issues, issues and trends in cancer care, investigational/new drug development, and bone marrow transplantation. Nurses employed in community settings and those living outside metropolitan areas tended to indicate the highest numbers of strong training needs. However, comparison of the needs for cancer prevention and detection education by regions showed that for none of the geographic regions was a high training need for cancer prevention and detection identified.

Clinical Competence↗
PubMed1994

Predictors of health-promoting lifestyles in persons with disabilities.

Persons with disabilities have been largely overlooked in investigations of health and health behaviors. The primary purpose of this descriptive correlational study was to examine the usefulness of Pender's (1987) Health Promotion Model in explaining the occurrence of health-promoting behaviors among adults with disabilities. Hierarchical multiple regression analyses were used to analyze questionnaire responses from a sample of 117 adults with disabilities. Adults with disabilities were more likely to engage in a health-promoting lifestyle if they had higher specific self-efficacy for health behaviors, higher general self-efficacy, a wellness-oriented definition of health, required less mechanical assistance, and were female. Findings from this study suggest that interventions aimed at enhancing health promotion behaviors among persons with disabilities would be strengthened by addressing perceived ability to master situations, particularly the ability to successfully carry out health-promoting behaviors.

Activities of Daily Living↗
PubMed1989

Health promoting attitudes and behaviors among persons with disabilities.

Despite the recognized importance of maintaining and improving the health status of persons with disabilities, there has been little research conducted to determine their health care attitudes and behaviors and what interventions might serve to enhance their health. Using Pender's Model of Health Promotion (1987), this study investigated the factors associated with the occurrence of health promoting behaviors among 135 adults with disabilities. Staff and peer counsellors from two Independent Living Centres in Texas administered the questionnaires and conducted brief semi-structured interviews with participants. Seventy-three percent of the sample rated their current health as good or excellent. Findings from both interviews and questionnaires suggest that participants are more likely to define health as being able to function well than as simply the absence of illness. High scores on Adaptive definition of health, the Self-Efficacy-Scale, age, and low scores on the Barriers to Health Promotion Activity for Disabled Persons scale accounted for 31% of the variance in scores on a self-report measure of health promoting behaviors. These findings suggest that interventions which address self-perceived barriers to health promotion, work to build participants' sense of mastery of their health behaviors, and encourage a definition of health that is broader than simply absence of illness may be more effective than those that focus only on information about good health practices.

Adolescent↗
PubMed1988

Planning for health services for the elderly.

In order to create health services that effectively respond to the changing picture of health, governments should try to anticipate the health needs for the future. The scenarios for the elderly that are briefly discussed in this paper are approximations of developments that are largely autonomous if considered from the position of the individuals and organizations responsible for policies on health and health services. The three contextual scenarios developed are based on the forecasts, explorations and speculations to be found in the literature and also on the outcome of discussions with groups of experts in the fields of medical, biological and technological research and practice. The following variables have been incorporated in the study preparing the scenarios: demographic developments, the health status of the elderly, health services for the elderly, developments in medical, biological and technological fields, and societal developments, both economic and social. These scenarios provide policy makers with a learning environment in which they can test the strategies that are considered to answer the questions that they face, and evaluate the particular circumstances in which these strategies might be feasible.

Aged↗
PubMed1986

[Turning gray and social inequality].

In an ideal typical way the cohorts 1920 and 1930 are sketched. In economical and social respects these cohorts illustrate the emergence of new social inequalities and social tension. The cohorts fit into a hypothesized pattern of four generations, that is characteristic for the Netherlands at this time. At last some social and scientific perspectives of the greying of the Netherlands are considered.

Aged↗
PubMedDate not supplied

Indicators of critical thinking, communication, and therapeutic intervention among first-line nursing supervisors.

With the focus of the National League for Nursing on therapeutic intervention, critical thinking, and communication skills, nursing programs are challenged to measure these outcomes for their BSN graduates. The authors report the use of the Critical Incident Technique to identify behavioral indicators of communication, critical thinking, and therapeutic intervention skills from first-line nursing supervisors' descriptions of exemplary nursing practice.

Clinical Competence↗