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Biomedical subjects

J J Carlson

Publications and source records attributed to J J Carlson.

7 recordsLinked to original sources
PubMed2001

A GCN4 variant with a C-terminal basic region binds to DNA with wild-type affinity.

Basic-region leucine zipper (bZip) proteins contain a bipartite DNA-binding motif consisting of a leucine zipper dimerization domain and a basic region that directly contacts DNA. In all naturally occurring bZip proteins, the basic region is positioned N-terminal to the leucine zipper. We have designed a series of model bZip peptides in which the basic region of the yeast transcriptional activator GCN4 is placed C-terminal to its leucine zipper. DNA-binding studies demonstrate that the optimal reverse GCN4 (rGCN4) peptide is able to bind specifically and with wild-type affinity to DNA despite this unnatural arrangement of the two subdomains. These results suggest that a thermodynamic basis for the observed N-terminal positioning of the basic region relative to the dimerization domain is unlikely.

Amino Acid Sequence↗
PubMed2001

The effect of a garlic preparation on plasma lipid levels in moderately hypercholesterolemic adults.

Lipid management is well established as an effective preventive and management tool for cardiovascular disease (CVD). Health claims regarding the cholesterol lowering benefits of garlic are widespread. However, the clinical trial data are inconsistent. The effect of two doses of a commercial garlic preparation on plasma lipids were evaluated, compared to a placebo, in moderately hypercholesterolemic adults (baseline low density lipoprotein cholesterol (LDL-C)=157. 4+/-18.7, mean+/-S.D.). Fifty-one adults, aged 51.8+/-8.3 years participated in a double-blind, placebo-controlled, parallel treatment trial conducted in an outpatient research clinic. They were randomized to a placebo or a garlic botanical blend providing 500 or 1000 mg dehydrated garlic powder/day (three groups, 16-18 subjects per group). Plasma lipids were assessed every 2 weeks for 12 weeks. The study was designed with sufficient power to detect a 10% relative decline in LDL-C. The absolute mean changes in LDL-C over 12 weeks were 0.0+/-4.3, +1.4+/-4.8, and -10.1+/-6.8 mg/dl for the placebo, half-dose and full-dose, respectively. In the full-dose group, the LDL-C decrease of 6.1% was not significantly different from the other groups (P=0.5). No significant differences were observed for total- or high-density lipoprotein cholesterol (HDL-C), or triacylglycerol levels. In conclusion, the garlic powder preparation used in this study among moderately hypercholesterolemic adults did not significantly effect plasma lipids levels. There was no indication of a graded affect by garlic dose over the range of 0, 500 and 1000 mg/day. A small (<10%) effect on LDL-C levels or a threshold effect requiring larger doses are not eliminated by this study.

Adult↗
PubMed2000

Program participation, exercise adherence, cardiovascular outcomes, and program cost of traditional versus modified cardiac rehabilitation.

Common concerns with the traditional protocol (TP) for cardiac rehabilitation include suboptimal program participation, poor facilitation of independent exercise, the use of costly continuous electrocardiographic (ECG) monitoring, and lack of insurance reimbursement. To address these concerns, a reduced cost-modified protocol (MP) was developed to promote independent exercise. Eighty low- to moderate-risk cardiac patients were randomized to a TP (n = 42) or a MP (n = 38) and were compared over 6 months on program participation, exercise adherence, cardiovascular outcomes, and program costs. During month 1, patients followed identical regimens, including 3 ECG-monitored exercise sessions/week, with encouragement to achieve >/=5 thirty-minute sessions/week. In week 5, the TP continued with a facility-based regimen including 3 exercise sessions/week for 6 months and used ECG monitoring the initial 3 months. The MP discontinued ECG monitoring in week 5 and were gradually weaned to an off-site exercise regimen that was complemented with educational support meetings and telephone follow-up. Compared with TP patients, MP patients had higher rates of off-site exercise over 6 months (p = 0.05), and total exercise (on site + off site) during the final 3 months (p = 0.03). Also, MP patients were less likely to drop out (p = 0.05). Both protocols promoted comparable improvements in maximal oxygen uptake (p <0.05), blood lipids (p <0.001), and hemodynamic measurements (p <0.002). The MP cost $738 less/patient than the TP and required 30% less staff (full-time equivalents). These results suggest that a reduced cost MP was as effective as an established TP in improving physiologic outcomes while demonstrating higher rates of exercise adherence and program participation. Thus, the MP or a similar protocol has applicability to hospitals with large capitated or managed care populations to provide cost-effective cardiovascular risk reduction to patients.

Adult↗
PubMed1998

Effects of sampling interval on peak oxygen consumption in patients evaluated for heart transplantation.

BACKGROUND AND METHODS: Peak oxygen consumption is a commonly accepted criterion in patient selection for cardiac transplantation. To determine the effect of various gas exchange sampling intervals on the variability of peak oxygen consumption, 15 consecutive patients evaluated for cardiac transplantation performed maximal treadmill testing using a ramped protocol. Oxygen consumption was measured via breath-by-breath analysis of expired air. Peak oxygen consumption was determined for each test using the following sampling intervals: 60-, 30-, and 15-s averages, eight breath rolling average, and true breath by breath. Variability of the mean peak oxygen consumption for each sample average was compared using analysis of variance on repeated measures. RESULTS AND CONCLUSIONS: Measures of peak oxygen consumption differed significantly (p<0.001) between sampling averages. A maximum variability of 20% was noted between the largest and smallest averages (13.8+/-4.2 mL/kg/min for 60 s vs 17.3+/-4.2 mL/kg/min for breath by breath). No significant difference was found between the 30-s, 15-s, and eight breath rolling averages (14.2+/-3.7 vs 14.5+/-3.9 vs 14.7+/-4.3 mL/kg/min), respectively. Results of the study suggest (1) the sampling average can have a significant effect on peak oxygen consumption influencing patient selection for transplantation, and (2) sample averages larger than breath by breath but smaller than 60 s be used for determination of peak oxygen consumption.

Exercise Test↗
PubMed1992

Effects of a 6-month incentive-based exercise program on adherence and work capacity.

The purpose of the study was to evaluate the effect of behavioral management techniques on exercise adherence linked to improvements in work capacity and maximal oxygen consumption (VO2max). One hundred thirty-seven participants in six different worksites on a university campus (five experimental and one comparison site) completed 6 months of a minimally supervised, incentive-based endurance exercise program. All participants in the experimental group contracted to engage in at least four bouts of 30 min of verified aerobic exercise within a prescribed target heart rate range each week for the duration of the program. Forty dollars deposited at the beginning of the program served as a response cost that could be lost as a result of failure to fulfill the weekly contracts. Individuals in the comparison group participated in a similar 6-month program but without the contracts and response cost strategies. Weekly adherence for both groups was strictly defined as verified fulfillment of all four bouts of exercise. Adherence for the experimental group was 97% by this definition, and adherence for the comparison group was 19% (P less than 0.01). VO2max increased 2.6% (P less than 0.01), and treadmill test time increased 16% (P less than 0.01) in the experimental group after the 6-month program, with no significant changes in the comparison group. Recovery heart rates at 2 and 4 min post-exercise were significantly lower at 6 months in the experimental group but not in the comparison group. These data provide evidence that adherence to a 6-month endurance exercise program can be improved significantly through the use of well conceived behavior management strategies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Self-efficacy, psychosocial factors, and exercise behavior in traditional versus modified cardiac rehabilitation.

BACKGROUND: Self-efficacy and social support are established determinants of exercise adherence and have potential usefulness for tailoring independent exercise regimens for cardiac patients. Highly supervised traditional cardiac rehabilitation programs may be a barrier for independent exercise self-efficacy in low - and moderate-risk patients. PURPOSE: The authors evaluated changes in psychosocial measures including self-efficacy and social support in 80 cardiac patients with low to moderate risk randomized to a traditional cardiac rehabilitation protocol (TP) or modified protocol (MP). These measures also were assessed for their potential to predict subsequent exercise behavior. METHODS: The TP (n = 38) emphasized a supervised exercise regimen and included continuous electrocardiogram (ECG) monitoring for 3 months. The lower cost MP (n = 42) emphasized independent exercise and included group education/support meetings, and gradually weaned patients from continuous ECG monitoring and direct medical supervision. RESULTS: Repeated measures analyses of variance indicated that MP patients had higher levels of self-efficacy for independent exercise without continuous ECG monitoring (P < .05). No other protocol differences were found. Multiple regression analyses using the pooled sample (excluding dropouts) indicated that self-efficacy for independent exercise was the only significant predictor of exercise over 6 months (R2=.28 [adjusted R2= .221 P < .01). In contrast to previous reports, social support for exercise was not a significant predictor of exercise behavior. CONCLUSIONS: These findings suggest cardiac rehabilitation programs for low- and moderate-risk patients should emphasize educational and patient monitoring methods that promote patient self-efficacy for independent exercise. Programs that emphasize highly supervised exercise including longer term use of continuous ECG monitoring may impair self-efficacy for independent exercise. Longer-term studies are needed to fully determine the value of using psychosocial measures for designing individualized exercise programs and predicting long-term exercise behavior in cardiac patients.

Aged↗