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Biomedical subjects

J P Hecht

Publications and source records attributed to J P Hecht.

7 recordsLinked to original sources
PubMed2001

Smoking-cessation counseling in the home. Attitudes, beliefs, and behaviors of home healthcare nurses.

BACKGROUND: Despite advances in smoking treatment, cessation rates remain stagnant, possibly a function of the lack of new channels to reach heavily addicted smokers. This cross-sectional study examined home care nurses' attitudes, beliefs, and counseling behaviors regarding counseling their home care patients who smoke. METHODS: Home healthcare nurses (N=98) from the Visiting Nurse Association of Rhode Island were randomly selected to participate in a study helping home-bound medically ill smokers to quit. At baseline, nurses completed a questionnaire that assessed a constellation of cognitive factors (self-efficacy, outcome expectations, perceived effectiveness, risk perception, motivation, and perceived patient adherence) as correlates of self-reported nurse counseling behaviors. RESULTS: Nurses with higher outcome expectations spent more time counseling their patients about quitting (p<0.04). Nurses' self-efficacy was the only variable associated with consistent counseling (p<0.05). While the majority of nurses "asked and advised" their patients, a minority of nurses "assisted or arranged" follow-up. Perceived importance of counseling was associated with a greater likelihood of asking, advising and assisting (p<0.05). None of the nurses who currently smoked (n=13) provided follow-up to their patients. Nurses who reported higher levels of both risk perception (regarding the harmful effects of smoking) and perceived effectiveness were more likely to recommend the nicotine patch. CONCLUSIONS: Attitudes and beliefs about smoking are significantly associated with nurse counseling behaviors. Helping nurses to overcome their barriers to smoking counseling may open up new channels for smoking intervention.

Adult↗
PubMed1990

Thermodynamics of Ca2+ transport through sarcoplasmic reticulum membranes during the transient-state of simulated reactions.

The kinetics of a chemical model of Ca2+ transport and coupled ATPase activity in sarcoplasmic reticulum membranes were solved for the transient-state of simulated reactions, using a numerical integration procedure. The simulation conditions reproduced in vitro experiments using either fragmented membranes or vesicles with Ca2+ accumulating ability. The results yielded the concentrations of all the ligands and intermediates of the enzymatic cycle as a function of the reaction time. These results were applied to calculations of several thermodynamic variables: (1) the step by step profile of the standard free energy change of the cycle. (2) The step by profile of the actual free energy change of the cycle, and its evolution with the reaction time. (3) The separate contributions of ATP hydrolysis and Ca2+ transport to the overall free energy change with the reaction. (4) The dependence of the velocity of the free energy change with the reaction time. (5) The efficiency of the transport system, and its change with the reaction time. (6) The separate contributions of the Ca2+ gradient and some enzymatic intermediates as free energy stores. The main findings are: (1) the step by step diagrams of the free energy change calculated from the results of the kinetic analysis better describe the thermodynamic profile of the cycle than previously reported diagrams of the standard free energy and basic free energy changes. The relative contribution of each partial step to the driving force of the whole reactions, as well as their changes upon the advancement of the reactions, are derived from the diagrams. (2) Free energy yielded by ATP hydrolysis is stored by the system, not only as a Ca2+ gradient, but also as enzymatic intermediates of the reaction. The progressive increase of both free energy pools upon the advancement of the reaction is quantitated.

Animals↗
PubMed1990

A BASIC program for the numerical solution of the transient kinetics of complex biochemical models.

A highly optimized software for the kinetic analysis of complex chemical models is presented. The program is applied to the analysis of a vectorial biochemical reaction, where many species are linked by multiple equilibria of any order. The reaction stimulates the Ca2(+)-transport-linked ATPase reaction taking place in a suspension of vesicular fragments of isolated sarcoplasmic reticulum membranes, as described in many experimental reports. The model includes 12 reactants and intermediate chemical species, 14 kinetic constants, compartmentalization, and thermodynamic adjustment. The concentrations of all the model components, at any time, starting from a known initial condition, are calculated. The transient concentrations of the species are obtained by numerical integration of the appropriate differential equations, using an optimized version of the Runge-Kutta-Gill algorithm, with the aid of a Digital PDP11/23 computer and a standard BASIC-11 software, which could be fast and easily fitted to work with any microcomputer and/or alternative language or faster working compiled BASIC version. The errors of the calculations are evaluated.

Biochemistry↗
PubMed1986

Equilibrium and steady state thermodynamics of active transport systems studied on simple models simulating Ca2+ transport through sarcoplasmic reticulum membranes.

Equilibrium and steady state conditions of primary active transport systems are analyzed in models simulating well known characteristics of calcium transport through sarcoplasmic reticulum membranes. The model for the equilibrium simulations is a closed system with two compartments and a vectorial chemical reaction coupling Ca transport and ATP breakdown. The chemical potential difference for Ca (delta mu Ca) is calculated as a function of the total amount of Ca (Cat) and nucleotides (Nt) in the system. Results are obtained by successive approximations along the thermodynamic pathway of the reaction, up to minimizing free energy of the system, since the solution of the explicit equations cannot be obtained with computers of current precision for data within physiological ranges. delta mu Ca and [Caout] are extremely dependent on Cat and Nt for certain combinations of the variables, i.e. [Caout] can be raised from 10(-8) to 10(-6) M when Cat varies from 0.998 to 1.002 mM, therefore, the running force of the spontaneous reaction is largely shifted by tiny changes in the parameters of the system. For steady state simulations, ATP supply to the system, ADP and Pi drainage, and Ca diffusion through the barrier, are assumed. Again, conditions within physiological ranges can be found where tiny changes in Cat, the rate of ATP supply, diffusion, the ratio between the volumes of the compartments, or a relative uncoupling between the transport and hydrolytic reactions, largely shifts delta mu Ca and [Caout], thus making the steady state highly unstable and therefore well designed to operate as an amplifier of physiological signals. The equilibrium model describes some physicochemical characteristics of the system; the steady state model is more useful to simulate several physiological situations.

Adenosine Diphosphate↗
PubMedDate not supplied

Smoking interventions for patients with cancer: guidelines for nursing practice.

PURPOSE/OBJECTIVES: To identify strategies for oncology nurses to assist patients with cancer in modifying their smoking behaviors. DATA SOURCES: Published research articles, conference proceedings, Surgeon General Reports, and book chapters. DATA SYNTHESIS: Cigarette smoking is associated with a variety of cancers, and persistent smoking following a cancer diagnosis contributes to increased morbidity and mortality. Smoking cessation affords numerous health benefits to patients with cancer, including improved respiratory functioning, increased activity tolerance, and a personal sense of accomplishment. To date, few smoking interventions have targeted patients with cancer. CONCLUSIONS: Oncology nurses can become more actively involved in effective smoking interventions by incorporating current research findings and theoretical models of behavior change into daily practice. NURSING IMPLICATIONS: Oncology nurses can more effectively help their patients who smoke by assessing smoking status and patients' readiness to quit; providing brief, supportive messages consistently over time; offering or referring patients to appropriate resources; and providing continued follow-up.

Behavior Therapy↗