Comparing GPS, Log, Survey, and Accelerometry to Measure Physical Activity.

OBJECTIVES: We explored how objectively measured global positioning system (GPS) and accelerometer data match with travel logs and questionnaires in predicting trip duration and physical activity (PA). METHODS: 99 participants wore GPS devices and accelerometers, and recorded all trips in a log for 5 consecutive days. Participants also completed a self-administered questionnaire on PA and travel behaviors. RESULTS: There was good agreement between GPS and log for assessment of trip duration, although log measures overestimated trip duration (concordance correlation coefficient 0.53 [0.47, 0.59]; Bland-Altman estimate 0.76 [0.16, 3.71] comparing GPS to log). Log measures underestimated light PA and overestimated moderate PA compared to accelerometry when greater than zero moderate PA was reported. CONCLUSIONS: It is often not feasible to deploy accelerometry or GPS devices in population research because these devices are expensive and require technical expertise and data processing. Questionnaires and logs provide inexpensive tools to assess PA and travel with reasonable concordance with objective measures. However, they have shortcomings in evaluating the presence and amount of light and moderate PA. Future questionnaires and logs should be developed to evaluate sensitivity to light and moderate PA.

ßENaC is required for whole cell mechanically gated currents in renal vascular smooth muscle cells.

Myogenic constrictor responses in small renal arteries and afferent arterioles are suppressed in mice with reduced levels of ß-epithelial Na⁺ channel (ßENaC(m/m)). The underlying mechanism is unclear. Decreased activity of voltage-gated calcium channels (VGCC) or mechanically gated ion channels and increased activity of large conductance calcium-activated potassium (BK) channels are a few possible mechanisms. The purpose of this study was to determine if VGCC, BK, or mechanically gated ion channel activity was altered in renal vascular smooth muscle cell (VSMC) from ßENaC(m/m) mice. To address this, we used whole cell patch-clamp electrophysiological approaches in freshly isolated renal VSMCs. Compared with ßENaC(+/+) controls, the current-voltage relationships for VGCC and BK activity are similar in ßENaC(m/m) mice. These findings suggest neither VGCC nor BK channel dysfunction accounts for reduced myogenic constriction in ßENaC(m/m) mice. We then examined mechanically gated currents using a novel in vitro assay where VSMCs are mechanically activated by stretching an underlying elastomer. We found the mechanically gated currents, predominantly carried by Na⁺, are observed with less frequency (87 vs. 43%) and have smaller magnitude (-54.1 ± 12.5 vs. -20.9 ± 4.9 pA) in renal VSMCs from ßENaC(m/m) mice. Residual currents are expected in this model since VSMC ßENaC expression is reduced by 50%. These findings suggest ßENaC is required for normal mechanically gated currents in renal VSMCs and their disruption may account for the reduced myogenic constriction in the ßENaC(m/m) model. Our findings are consistent with the role of ßENaC as a VSMC mechanosensor and function of evolutionarily related nematode degenerin proteins.

Changes in physical activity and travel behaviors in residents of a mixed-use development.

BACKGROUND: Mixed-use developments may be especially promising settings for encouraging walking and other types of physical activity. PURPOSE: This study examined the physical activity and travel behaviors of individuals before and after they relocated to Atlantic Station, a mixed-use redevelopment community in metropolitan Atlanta. METHODS: A survey study was conducted to compare the behaviors, experiences, and attitudes of Atlantic Station residents before and after moving to a mixed-use neighborhood. Data were collected in 2008 and 2009 and analyzed in 2010. Key dependent variables were self-reported physical activity and travel behaviors including walking for recreation and transport, automobile use, and use of public transportation. RESULTS: Study participants included 101 adult residents of Atlantic Station, most of whom were female, young, and well educated. There were significant increases in walking for recreation or fitness (46%-54%; p<0.05) and walking for transportation (44%-84%; p<0.001) after moving into the mixed-use development. Respondents also reported reduced automobile travel and increased time spent using public transportation after moving to Atlantic Station. Because this study used individuals as their own controls, there is more control over confounding lifestyle variables compared to cross-sectional studies of individuals living in different neighborhoods. CONCLUSIONS: Adults who move to a denser, mixed-use neighborhood increase their levels of walking for both recreation and transportation, decrease their automobile travel, and increase their use of public transportation.

Pre-transplant therapy for hepatocellular carcinoma is associated with a lower recurrence after liver transplantation.

BACKGROUND: Hepatic transplantation has been advocated as an effective treatment for hepatocellular carcinoma (HCC). We seek to determine if pre-transplant therapies can reduce post-transplant recurrence. METHODS: We conducted a retrospective review of prospective data in patients undergoing transplantation for HCC 2001-2006. Patients were followed for recurrence every six months with abdominal computerized tomography or magnetic resonance imaging. Logistic regression analyzed recipient factors such as prior treatment for HCC, donor, operative, and tumor factors in comparing patients developing HCC recurrence with those without recurrence. RESULTS: During the study period, we performed 124 hepatic transplants for HCC [age: 55 +/- 7.6 yr; 104 (85%) male, 81 (66%) white, and 32 (26%) Asian]. Recurrence was found in nine at a mean of 2.6 yr follow-up. Thirty-three patients (27%) had pre-transplant treatment (radiofrequency ablation, transarterial chemoembolization or percutaneous ethanol injection). Univariable logistic regression identified nine factors [body mass index, Asian race, hepatitis B, prior HCC therapy, alpha-fetoprotein (AFP), model for end-stage liver disease (MELD) score, bilirubin, and international normalized ratio] predictive of HCC recurrence at a level of p < 0.1. Multiple logistic regression analysis of six of the nine selected factors demonstrated AFP level >1000, calculated pre-transplant MELD score <14, and the lack of any pre-transplant treatment were significantly associated with recurrence of HCC. No patient with prior HCC therapy had recurrence. CONCLUSIONS: In patients with HCC awaiting hepatic transplantation, there is a reduced rate of recurrence of HCC if tumors are pre-treated with liver-directed therapy. By treating HCC tumors with any type of treatment prior to transplant, we can significantly reduce the odds of HCC recurrence after transplant.

Promoting appropriate antibiotic use for pediatric patients: a social ecological framework.

During the 1990s, the number of prescriptions for antibiotics for children and adolescents finally decreased after more than a decade of alarming increases. The Centers for Disease Control and Prevention (CDC) and many other groups have designed and implemented interventions to promote appropriate prescribing of antibiotics, and these efforts appear to have contributed to recent decreases in rates of such prescribing. In this article, we describe the various types of interventions that the CDC and others are using to encourage appropriate use of antibiotics. A social ecological framework is used to describe the various factors contributing to prescribing and using antibiotics, as well as the interventions used for targeting these factors. Although most efforts promoting appropriate use of antibiotics have focused on reducing such use for viral infections, future efforts also should include a focus on ensuring the use of targeted agents when antibiotics are indicated.