Biomedical subjects

James H Johnson

Publications and source records attributed to James H Johnson.

7 recordsLinked to original sources

PubMed2006

Preferred method of selecting exercise intensity in adult women.

Heart rate (HR) and rating of perceived exertion (RPE) are both recommended methods of determining exercise intensity for healthy adults. The purpose of this study was to determine how adult women self-select their exercise intensity during aerobic exercise. We interviewed 100 women exercisers who had been engaged regularly in an exercise program for at least 3 months to determine their method of gauging aerobic exercise intensity. Subjects exercised for about 45.1 +/- 21.4 minutes per session (4.4 +/- 1.4 times per week). The vast majority (84%) exclusively used self-selected effort perception to monitor their exercise intensity. Only 16% were familiar with an RPE chart. Although HR is touted heavily in fitness centers and on aerobic ergometers, self-selected effort perception (and not HR) is the method of choice by women who are experienced at aerobic exercise. It is recommended that fitness center personnel increase their efforts to educate the public regarding the appropriate use of effort perception as a method of gauging exercise intensity.

Adult↗

PubMed2005

Dendrimer enhanced ultrafiltration. 1. Recovery of Cu(II) from aqueous solutions using PAMAM dendrimers with ethylene diamine core and terminal NH2 groups.

This article discusses the feasibility of using dendrimer enhanced ultrafiltration (DEUF)to recover Cu(II) from aqueous solutions. Building upon the results of fundamental investigations of Cu(II) binding to PAMAM dendrimers with ethylenediamine (EDA) core and terminal NH2 groups, we combine (i) dead-end ultrafiltration (UF) experiments with (ii) atomic force microscopy (AFM) characterization of membrane fouling to assess the feasibility of using DEUF to recover Cu(II) from aqueous solutions. On a mass basis, the Cu(II) binding capacities of the EDA core PAMAM dendrimers are much larger and more sensitive to solution pH than those of linear polymers with amine groups. The dendrimer-Cu(II) complexes can be efficiently separated from aqueous solutions by ultrafiltration. The metal ion laden dendrimers can be regenerated by decreasing the solution pH to 4.0; thus enabling the recovery of the bound Cu(II) ions and recycling of the dendrimers. The UF measurements and AFM characterization studies show that EDA core PAMAM dendrimers with terminal NH2 groups have very lowtendency to foul the commercially available regenerated cellulose (RC) membranes evaluated in this study. The overall results of these experiments suggest that DEUF is a promising process for recovering metal ions such as Cu(II) from aqueous solutions.

Cellulose↗

PubMed2004

Dendritic chelating agents. 1. Cu(II) binding to ethylene diamine core poly(amidoamine) dendrimers in aqueous solutions.

This paper describes an investigation of the uptake of Cu(II) by poly(amidoamine) (PAMAM) dendrimers with an ethylenediamine (EDA) core in aqueous solutions. We use bench scale measurements of proton and metal ion binding to assess the effects of (i) metal ion-dendrimer loading, (ii) dendrimer generation/terminal group chemistry, and (iii) solution pH on the extent of binding of Cu(II) in aqueous solutions of EDA core PAMAM dendrimers with primary amine, succinamic acid, glycidol, and acetamide terminal groups. We employ extended X-ray absorption fine structure (EXAFS) spectroscopy to probe the structures of Cu(II) complexes with Gx-NH2 EDA core PAMAM dendrimers in aqueous solutions at pH 7.0. The overall results of the proton and metal ion binding measurements suggest that the uptake of Cu(II) by EDA core PAMAM dendrimers involves both the dendrimer tertiary amine and terminal groups. However, the extents of protonation of these groups control the ability of the dendrimers to bind Cu(II). Analysis of the EXAFS spectra suggests that Cu(II) forms octahedral complexes involving the tertiary amine groups of Gx-NH2 EDA core PAMAM dendrimers at pH 7.0. The central Cu(II) metal ion of each of these complexes appears to be coordinated to 2-4 dendrimer tertiary amine groups located in the equatorial plane and 2 axial water molecules. Finally, we combine the results of our experiments with literature data to formulate and evaluate a phenomenological model of Cu(II) uptake by Gx-NH2 PAMAM dendrimers in aqueous solutions. At low metal ion-dendrimer loadings, the model provides a good fit of the measured extent of binding of Cu(II) in aqueous solutions of G4-NH2 and G5-NH2 PAMAM dendrimers at pH 7.0.

Chelating Agents↗

PubMed2003

3-D structural modeling of humic acids through experimental characterization, computer assisted structure elucidation and atomistic simulations. 1. Chelsea soil humic acid.

This paper describes an integrated experimental and computational framework for developing 3-D structural models for humic acids (HAs). This approach combines experimental characterization, computer assisted structure elucidation (CASE), and atomistic simulations to generate all 3-D structural models or a representative sample of these models consistent with the analytical data and bulk thermodynamic/structural properties of HAs. To illustrate this methodology, structural data derived from elemental analysis, diffuse reflectance FT-IR spectroscopy, 1-D/2-D 1H and 13C solution NMR spectroscopy, and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI QqTOF MS) are employed as input to the CASE program SIGNATURE to generate all 3-D structural models for Chelsea soil humic acid (HA). These models are subsequently used as starting 3-D structures to carry out constant temperature-constant pressure molecular dynamics simulations to estimate their bulk densities and Hildebrand solubility parameters. Surprisingly, only a few model isomers are found to exhibit molecular compositions and bulk thermodynamic properties consistent with the experimental data. The simulated 13C NMR spectrum of an equimolar mixture of these model isomers compares favorably with the measured spectrum of Chelsea soil HA.

Humic Substances↗

PubMed2002

Importance of dissection in learning anatomy: personal dissection versus peer teaching.

Two studies or approaches to time savings in teaching gross anatomy were implemented and tested. Personal dissection vs. peer teaching of the upper and lower extremities revealed subtle effects of dissection on examination performance. Although peer teaching was generally successful, students preferred to dissect for themselves, lacking confidence in being taught by other students. ANOVA and multiple range tests carried out on the examination means indicated no difference between each student's scores on upper and lower extremity questions. However, subtle effects were reflected in significant differences (P < 0.05) in both ratio (upper%/lower%) and difference (upper%-lower%) between each student's percent scores on upper extremity and lower extremity questions, indicating enhanced performance on the extremity dissected. Students dissecting both extremities were intermediate in both ratio and difference, and not significantly different from either the "upper" or "lower" extremity groups. A questionnaire indicated that students who dissected only one extremity would have preferred to have dissected both extremities, and, contrary to overall examination performance, disagreed that they had learned both extremities at a satisfactory level. Although documenting adequate learning with time savings, the results are consistent with the contention that hands-on dissection enhances learning and confidence in the subject matter, because examination performance as well as personal satisfaction was enhanced on the extremity that was dissected.

Anatomy↗

PubMedDate not supplied

The crucible of public health practice: major trends shaping the design of the Management Academy for Public Health.

Public health leaders and managers need new leadership and management skills as well as greater entrepreneurial acumen to respond effectively to broad demographic, socioeconomic, and political trends reshaping public health. This article asserts that the need for such training and skills was the impetus for the conceptualization, design, and launch of the Management Academy for Public Health--an innovative executive education program jointly offered by the schools of business and public health at the University of North Carolina at Chapel Hill.

Entrepreneurship↗

PubMedDate not supplied

The UNC Management Academy for Public Health: how the UNC School of Public Health and the Kenan-Flagler Business School created a winning partnership.

The University of North Carolina Management Academy for Public Health is a unique training program that combines a business education with a public health focus, to enhance the performance of individual public health managers and improve organizational strength throughout governmental public health. This article considers the implications of decisions made in creating this program, which, after initial funding through the Centers for Disease Control and Prevention Foundation, is now self-sustaining through participant fees. It details the principles behind the program's design, curriculum, evaluation, and sustainability strategies; presents results of the ongoing partnership; and draws conclusions about the program's future ability to meet a national need for public health management training.

Centers for Disease Control and Prevention, U.S.↗