Daniel Rubin, Doctoral Dissertation Advisor (AC)
Using agent based modeling to assess the effect of increased Bus Rapid Transit system infrastructure on walking for transportation.
2016; 88: 39–45
The effect of transport infrastructure on walking is of interest to researchers because it provides an opportunity, from the public policy point of view, to increase physical activity (PA). We use an agent based model (ABM) to examine the effect of transport infrastructure on walking. Particular relevance is given to assess the effect of the growth of the Bus Rapid Transit (BRT) system in Bogotá on walking. In the ABM agents are assigned a home, work location, and socioeconomic status (SES) based on which they are assigned income for transportation. Individuals must decide between the available modes of transport (i.e., car, taxi, bus, BRT, and walking) as the means of reaching their destination, based on resources and needed travel time. We calibrated the model based on Bogota's 2011 mobility survey. The ABM results are consistent with previous empirical findings, increasing BRT access does indeed increase the number of minutes that individuals walk for transportation, although this effect also depends on the availability of other transport modes. The model indicates a saturation process: as more BRT lanes are added, the increment in minutes walking becomes smaller, and eventually the walking time decreases. Our findings on the potential contribution of the expansion of the BRT system to walking for transportation suggest that ABMs may prove helpful in designing policies to continue promoting walking.
View details for DOI 10.1016/j.ypmed.2016.03.015
View details for PubMedID 27012602
TransMilenio, a Scalable Bus Rapid Transit System for Promoting Physical Activity.
Journal of urban health : bulletin of the New York Academy of Medicine
2016; 93 (2): 256–70
Transport systems can play an important role in increasing physical activity (PA). Bogotá has been recognized for its bus rapid transit (BRT) system, TransMilenio (TM). To date, BRTs have been implemented in over 160 cities worldwide. The aim of this study was to assess the association between PA and the use of TM among adults in Bogotá. The study consists of a cross-sectional study conducted from 2010 to 2011 with 1000 adults. PA was measured using the International Physical Activity Questionnaire. In a subsample of 250 adults, PA was objectively measured using ActiGraph accelerometers. Analyses were conducted using multilevel logistic regression models. The use of TM was associated with meeting moderate-to-vigorous PA (MVPA). TM users were more likely to complete an average of >22 min a day of MVPA (odds ratio [OR] = 3.1, confidence interval [CI] = 95 % 1.4-7.1) and to walk for transportation for ≥150 min per week (OR = 1.5; CI = 95 % 1.1-2.0). The use of TM was associated with 12 or more minutes of MVPA (95 % CI 4.5-19.4, p < 0.0001). Associations between meeting PA recommendations and use of TM did not differ by socioeconomic status (p value = 0.106) or sex (p value = 0.288). The use of TM is a promising strategy for enhancing public health efforts to reduce physical inactivity through walking for transport. Given the expansion of BRTs, these results could inform the development of transport PA programs in low- to high-income countries.
View details for DOI 10.1007/s11524-015-0019-4
View details for PubMedID 26883031
View details for PubMedCentralID PMC4835357
TrkB gene therapy by adeno-associated virus enhances recovery after cervical spinal cord injury.
2016; 276: 31–40
Unilateral cervical spinal cord hemisection at C2 (C2SH) interrupts descending bulbospinal inputs to phrenic motoneurons, paralyzing the diaphragm muscle. Recovery after C2SH is enhanced by brain derived neurotrophic factor (BDNF) signaling via the tropomyosin-related kinase subtype B (TrkB) receptor in phrenic motoneurons. The role for gene therapy using adeno-associated virus (AAV)-mediated delivery of TrkB to phrenic motoneurons is not known. The present study determined the therapeutic efficacy of intrapleural delivery of AAV7 encoding for full-length TrkB (AAV-TrkB) to phrenic motoneurons 3 days post-C2SH. Diaphragm EMG was recorded chronically in male rats (n=26) up to 21 days post-C2SH. Absent ipsilateral diaphragm EMG activity was verified 3 days post-C2SH. A greater proportion of animals displayed recovery of ipsilateral diaphragm EMG activity during eupnea by 14 and 21 days post-SH after AAV-TrkB (10/15) compared to AAV-GFP treatment (2/11; p=0.031). Diaphragm EMG amplitude increased over time post-C2SH (p<0.001), and by 14 days post-C2SH, AAV-TrkB treated animals displaying recovery achieved 48% of the pre-injury values compared to 27% in AAV-GFP treated animals. Phrenic motoneuron mRNA expression of glutamatergic AMPA and NMDA receptors revealed a significant, positive correlation (r(2)=0.82), with increased motoneuron NMDA expression evident in animals treated with AAV-TrkB and that displayed recovery after C2SH. Overall, gene therapy using intrapleural delivery of AAV-TrkB to phrenic motoneurons is sufficient to promote recovery of diaphragm activity, adding a novel potential intervention that can be administered after upper cervical spinal cord injury to improve impaired respiratory function.
View details for DOI 10.1016/j.expneurol.2015.11.007
View details for PubMedID 26607912
View details for PubMedCentralID PMC4715974
Changes to circulating inflammatory cytokines in response to moderate exercise.
The Journal of sports medicine and physical fitness
2014; 56 (1-2): 100–104
Regular physical activity improves the metabolic profile of patients, although the biological mechanisms involved are not clear yet. The anti-inflammatory effects of exercise are well known and are possibly related to its therapeutic properties. The aim of this study was to compare changes in the concentration of an anti-inflammatory cytokine - tumor necrosis factor soluble receptor-1 (sTNFR1) - and a pro-inflammatory cytokine - interleukin-1β (IL-1β) - during moderate physical exercise in sedentary versus athletic men.We analyzed serum inflammatory cytokine concentrations in 5 athletes and 5 sedentary men (aged 18 to 22): 1) 15 minutes and immediately before a 28-minute specifically-programmed moderate exercise session; 2) every 3 minutes during the exercise session; 3) 15 and 30 minutes after session completion.We obtained serum sTNFR1 and IL-1β concentrations in 10 individuals. Both cytokines exhibited changes in their concentration during physical exercise: a significant increase in the concentration of sTNFR1 was observed in both the sedentary (P=0.0249) and the athlete (P=0.02172) groups. The levels of sTNFR1 were higher in the athlete group than in the sedentary group. No differences were observed in the IL-1β concentrations between the two groups.Serum concentration of the anti-inflammatory cytokine sTNFR1 increased during moderate physical exercise, and its levels were higher in athletes before, during and after physical activity. These findings are consistent with previous findings concerning the anti-inflammatory properties of exercise, and suggest that sTNFR1 has an important role in the anti-inflammatory environment following physical activity.
View details for PubMedID 25389637