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The purpose of this study is to develop and test a local measure of walkability in San Francisco County and evaluate walkability by race, ethnicity, and educational attainment at the census block group level. We used data collected as part of the 2019–2020 Bay Area Young Adult Health Study, wherein we conducted audits of 1525 randomly selected census blocks to assess domains, such as aesthetics, access to amenities, street safety, and topography, which we then imputed to the remaining blocks in the city for overall coverage. We linked the walkability index to 2015–2019 American Community Survey Data aggregating walkability to the block group level. We performed a geographically weighted regression to measure associations between walkability, race/ethnicity, and educational attainment and found significant negative associations between walkability and the percentage of non-Hispanic Black residents in specific neighborhoods and non-Hispanic Asian residents in all neighborhoods. We also found significant positive associations between the percentage of residents with a bachelor’s or higher degree and walkability. Inequities in walkability across neighborhoods in San Francisco County largely mirrored sociodemographic inequities. Our approach to constructing a walkability index points to a relatively efficient means of estimating fine-scale neighborhood characteristics in urban areas, and our findings suggest that investments in neighborhood infrastructure may positively impact walkability and address broader inequity concerns.

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Objective: The objective of the present study was to examine the effects of monosodium glutamate (MSG) on the contraction of visceral smooth muscle (VSM) of the duodenum in a rat model to understand the MSG-induced impairment of the function of the small intestine. Methods: Male albino rats of Charles Foster strain were exposed with MSG at three different dosages (632, 1264, and 2528 mg/kg BW/day) for 30-day duration. The records of the contraction of the duodenum were achieved with isotonic transducer (IT-2245) coupled with RMS-Polyrite D by our standard laboratory protocol. Results: We have observed potentiation of contraction of duodenum ex vivo dose-dependently in MSG exposed groups of rats compared to control. Furthermore, the enzymatic activity of acetylcholinesterase (AChE) in VSM tissue homogenate and expression of AChE protein in fixed duodenal muscle cell layers have been decreased in a dosage response manner comparing to control rats. We have found a significant decrease in the activities of some antioxidant enzymes such as Cu-Zn superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-s-transferase, and increase in the level of malondialdehyde in MSG exposed VSM tissue homogenate of the duodenum. We have also observed thickening of muscularis externa layer and increase in the number of muscle cells in circular and longitudinal muscle layers of the duodenal wall in transverse duodenal wall sections stained with eosin-hematoxylin. Conclusion: MSG potentiates the contraction of VSM of duodenum by augmenting the activity of intrinsic cholinergic efferents predominantly, and inducing oxidative stress and proliferating smooth muscle cells.