Associations of physical activity and inactivity before and during pregnancy with glucose tolerance

OBJECTIVE: To investigate associations of physical activity and television viewing before and during pregnancy with risk of gestational diabetes mellitus (GDM) and abnormal glucose tolerance, the combination of GDM with less severe impaired glucose tolerance. METHODS: We assessed duration and intensity of physical activity and time spent viewing television both before and during pregnancy among 1,805 women enrolled in Project Viva, a cohort study in eastern Massachusetts. We identified 1,493 (83%) women with normal glucose tolerance and 312 (17%) with abnormal glucose tolerance, including 91 (5%) with GDM based on clinical glucose tolerance test results. RESULTS: After adjustment for age, race or ethnicity, history of GDM, family history of diabetes, and prepregnancy body mass index, our data suggest that women who engaged in any vigorous physical activity in the year before pregnancy experienced a reduced risk of GDM (odds ratio [OR] 0.56, 95% confidence interval [CI] 0.33-0.95) and abnormal glucose tolerance (OR 0.76, 95% CI 0.57-1.00). Women who reported vigorous activity before pregnancy and light-to-moderate or vigorous activity during pregnancy appeared to have a lower risk of both GDM (OR 0.49, 95% CI 0.24-1.01) and abnormal glucose tolerance (OR 0.70, 95% CI 0.49-1.01) compared with women reporting these activities in neither time period. Walking and total physical activity provided modest benefits. We observed no association of television viewing before or during pregnancy with risk of GDM or abnormal glucose tolerance. CONCLUSION: Physical activity, especially vigorous activity before pregnancy and at least light-to-moderate activity during pregnancy, may reduce risk for abnormal glucose tolerance and GDM. LEVEL OF EVIDENCE: II-2.     

Magnetic nanoparticles for imaging dendritic cells

We report the development of superparamagnetic iron oxide (SPIOs) nanoparticles and investigate the migration of SPIO‐labeled dendritic cells (DCs) in a syngeneic mouse model using magnetic resonance (MR) imaging. The size of the dextran‐coated SPIO is roughly 30 nm, and the DCs are capable of independent uptake of these particles, although not at levels comparable to particle uptake in the presence of a transfecting reagent. On average, with the assistance of polylysine, the particles were efficiently delivered inside DCs within one hour of incubation. The SPIO particles occupy approximately 0.35% of cell surface and are equivalent to 34.6 pg of iron per cell. In vivo imaging demonstrated that the labeled cells migrated from the injection site in the footpad to the corresponding popliteal lymph node. The homing of labeled cells in the lymph nodes resulted in a signal drop of up to 79%. Furthermore, labeling DCs with SPIO particles did not compromise cell function, we demonstrated that SPIO‐enhanced MR imaging can be used to track the migration of DCs effectively in vivo. Magn Reson Med 63:1383–1390, 2010. © 2010 Wiley‐Liss, Inc.     

Diet during early pregnancy and development of gestational diabetes

Diet composition may be a modifiable predictor of risk for abnormal glucose tolerance during pregnancy. Prior studies suggest that diets high in total fat, saturated fat, red and processed meats, and with high glycaemic load increase the risk of developing gestational diabetes mellitus (GDM), while polyunsaturated fats, carbohydrates and fibre are protective. The aim of this study was to investigate associations of these and other nutrients and foods, including n-3 fatty acids, trans fats, whole grains and dietary patterns, with risk of GDM. We studied 1733 women with singleton pregnancies enrolled in Project Viva, a prospective pregnancy and birth cohort study in eastern MA. Using multinomial logistic regression, we examined associations of first trimester diet, assessed by validated food frequency questionnaire, with results of glucose tolerance testing at 26-28 weeks of gestation. A total of 91 women developed GDM and 206 women had impaired glucose tolerance (IGT). Pre-pregnancy body mass index (BMI) was a strong predictor for GDM risk (OR 3.44 [95% CI 1.88, 6.31] for pre-pregnancy BMI > or =30 vs. <25 kg/m(2)). After adjustment for confounders, the OR [95% CI] for risk of GDM for total dietary fat was 1.00 [0.96, 1.05], for saturated fat 0.98 [0.88, 1.08], for polyunsaturated fat 1.09 [0.94, 1.26], for trans fat 0.87 [0.51, 1.49], and for carbohydrates 1.00 [0.96, 1.03] per each 1% of total energy. The adjusted OR [95% CI] for risk of GDM for a one standard deviation increase in energy-adjusted glycaemic load (32 units, about two soft drinks) was 0.96 [0.76, 1.22] and for each daily serving of whole grains was 0.90 [0.73, 1.13]. Dietary patterns and intake of red and processed meats were not predictive of glucose tolerance outcome. Estimates for IGT were similar to those for GDM. Intake of n-3 fatty acids was associated with increased GDM risk (OR 1.11 [95% CI 1.02, 1.22] per each 300 mg/day), but not with IGT risk. Except for this finding, perhaps due to chance, these data do not show that nutrient or food intake in early pregnancy is linked to risk of GDM. Nutritional status entering pregnancy, as reflected by pre-pregnancy BMI, is probably more important than pregnancy diet in development of GDM.     

Cognitive motor interference during dual-task gait in essential tremor

BackgroundFunctional ambulation requires concurrent performance of motor and cognitive tasks, which may create interference (degraded performance) in either or both tasks. People with essential tremor (ET) demonstrate impairments in gait and cognitive function. In this study we examined the extent of interference between gait and cognition in people with ET and controls during dual-task gait.MethodsWe tested 62 controls and 151 ET participants (age range: 72–102). ET participants were divided into two groups based on median score on the modified Mini Mental State Examination. Participants walked at their preferred speed, and performed a verbal fluency task while walking. We analyzed gait velocity, cadence, stride length, double support time, stride time, step width, step time difference, coefficient of variation (CV) of stride time and stride length.ResultsVerbal fluency performance during gait was similar across groups (p = 0.68). Velocity, cadence and stride length were lowest whereas step time difference (p = 0.003), double support time (p = 0.009), stride time (p = 0.002) and stride time CV (p = 0.007) were highest for ET participants with lower cognitive scores (ETp-LCS), compared with ET participants with higher cognitive scores (ETp-HCS) and controls. ETp-LCS demonstrated greatest interference for double support time (p = 0.005), step time difference (p = 0.013) and stride time coefficient of variation (p = 0.03).ConclusionsETp-LCS demonstrated high levels of cognitive motor interference. Gait impairments during complex tasks may increase risk for falls for this subgroup and underscore the importance of clinical assessment of gait under simple and dual-task conditions.     

A Qualitative Study of Gestational Weight Gain Counseling and Tracking

Excessive gestational weight gain (GWG) predicts adverse pregnancy outcomes and later obesity risk for both mother and child. Women who receive GWG advice from their obstetric clinicians are more likely to gain the recommended amount, but many clinicians do not counsel their patients on GWG, pointing to the need for new strategies. Electronic medical records (EMRs) are a useful tool for tracking weight and supporting guideline-concordant care, but their use for care related to GWG has not been evaluated. We performed in-depth interviews with 16 obstetric clinicians from a multi-site group practice in Massachusetts that uses an EMR. We recorded, transcribed, coded, and analyzed the interviews using immersion-crystallization. Many respondents believed that GWG had “a lot” of influence on pregnancy and child health outcomes but that their patients did not consider it important. Most indicated that excessive GWG was a big or moderate problem in their practice, and that inadequate GWG was rarely a problem. All used an EMR feature that calculates total GWG at each visit. Many were enthusiastic about additional EMR-based supports, such as a reference for recommended GWG for each patient based on pre-pregnancy body mass index, a “growth chart” to plot actual and recommended GWG, and an alert to identify out-of-range gains, features which many felt would remind them to counsel patients about excessive weight gain. Additional decision support tools within EMRs would be well received by many clinicians and may help improve the frequency and accuracy of GWG tracking and counseling.     

Comparing physical activity questionnaires for youth: seasonal vs annual format

BACKGROUND: In large cohort studies of older children, self-report is the only practical way to assess physical activity. Assessing usual activity over the entire year is desirable, but children and adolescents may overestimate activities with high seasonal variability. Use of questionnaires in which individuals report each activity by season may improve accuracy. METHODS: A total of 6782 girls and 5110 boys, aged 9-14 years in 1996, completed self-administered activity questionnaires in 1996 and in 1997. In 1996, participants reported the average time spent in each of 17 activities during the previous 12 months; in 1997, we also asked for the average time spent in the previous year, but within each of the four seasons. RESULTS: Girls reported a median of 12.8 hours/week total activity in 1996 and 10.4 hours/week in 1997. For boys, the estimates were 15.5 hours/week and 13.4 hours/week, respectively. Girls and boys within 1-year age strata (e.g., comparison of 10-year olds in 1996 with 10-year olds in 1997) reported an average of 3.7 and 3.1 fewer hours per week, respectively, on the 1997 seasonal format versus the 1996 annual format questionnaire. In longitudinal analyses, the difference between the annual and the seasonal estimates was greater if participants did the activity in fewer seasons in 1997. CONCLUSIONS: In comparison to an annual format questionnaire, a seasonal format questionnaire may improve accuracy of self-report of physical activity by reducing over-reporting of activities in which pre-adolescents and adolescents engage in fewer seasons.