Diet quality, diet motives, and nutrition literacy of vegans, vegetarians, and semi-vegetarians.

OBJECTIVE: Limited research is available on how motivations to adopt plant-based diets and nutrition literacy influence diet quality. This study assessed diet quality, diet motives and nutrition literacy in vegans, vegetarians, and semi-vegetarians, and investigated predictors of dietary quality. DESIGN: Cross-sectional study, participants completed an online survey about diet-related motives and nutrition literacy. Dietary intake was assessed with the Diet History Questionnaire III and diet quality was calculated with the Healthy Eating Index (HEI)-2015. A one-way ANCOVA was used to compare diet quality, nutrition literacy, and diet motives among diets. Hierarchical regression analysis was performed to identify significant predictors of diet quality. SETTING: Online survey, participants were recruited through paid targeted social media (Facebook/Instagram) advertising. PARTICIPANTS: Adults following a plant-based diet, including 117 (52.5%) vegans, 51 (22.9%) vegetarians, and 55 (24.6%) semi-vegetarians. RESULTS: Vegans had higher HEI-2015 scores (80.8±6.5, p<0.001) compared to vegetarians (75.1±9.1), and semi-vegetarians (76.8±7.5). Most participants (74%) had good nutrition literacy scores. Total nutrition literacy did not differ between groups, but vegans had higher vegetarian nutrition literacy than vegetarians and semi-vegetarians (p<0.001). Ecological welfare, health, and sensory appeal were highly important to all participants. Motives accounted for 12.8% of the variance in diet quality scores. HEI-2015 scores were positively associated with motives of health and natural content, but negatively associated with weight control motivation (all p<0.05). CONCLUSIONS: Individuals following plant-based dietary patterns have high diet quality and nutrition literacy. Messages valuing intrinsic over extrinsic factors may facilitate healthier dietary adherence in this population.

A systematic review of callous-unemotional traits and attachment in children and adolescents.

METHODS: The systematic review and meta-analysis included 17 research articles from 1994 to 2022. Results were summarized by developmental periods. RESULTS: Attachment insecurity was associated with CU traits across development (r = .17). This association was marginally stronger for high-risk samples (e.g., clinical, justice) and for continuous attachment measures versus coding schemes. From early to middle childhood, attachment disorganization was associated with CU traits (r = .17). IMPLICATIONS: Research on attachment and CU traits in childhood is still in its infancy. Changes in attachment measures from childhood to adolescence make developmental comparisons difficult. Results suggest attachment as a potential developmental mechanism for youth with CU traits, however, the area requires more research.

Advancing college food security: priority research gaps.

Despite over a decade of both quantitative and qualitative studies, food insecurity among US college/university students remains a pervasive problem within higher education. The purpose of this perspective piece was to highlight research gaps in the area of college food insecurity and provide rationale for the research community to focus on these gaps going forward. A group of food insecurity researchers from a variety of higher education institutions across the United States identified five thematic areas of research gaps: screening and estimates of food insecurity; longitudinal changes in food insecurity; impact of food insecurity on broader health and academic outcomes; evaluation of impact, sustainability and cost effectiveness of existing programmes and initiatives; and state and federal policies and programmes. Within these thematic areas, nineteen specific research gaps were identified that have limited or no peer-reviewed, published research. These research gaps result in a limited understanding of the magnitude, severity and persistence of college food insecurity, the negative short- and long-term impacts of food insecurity on health, academic performance and overall college experience, and effective solutions and policies to prevent or meaningfully address food insecurity among college students. Research in these identified priority areas may help accelerate action and interdisciplinary collaboration to alleviate food insecurity among college students and play a critical role in informing the development or refinement of programmes and services that better support college student food security needs.

Development of a Highly Sensitive Hybrid LC/MS Assay for the Quantitative Measurement of CTLA-4 in Human T Cells.

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a check point protein expressed on the surface of T cells and plays a central role in regulating the immune response. In recent years, CTLA-4 has become a popular target for cancer immunotherapy in which blocking CTLA-4 can restore T-cell function and enhance the immune response against cancer. Currently, there are many CTLA-4 inhibitors in a variety of modalities, including cell therapies, which are being developed in both preclinical and clinical stages to further harness the potential of the target for the treatment of certain types of cancer. In drug discovery research, measuring the level of CTLA-4 in T cells is important for drug discovery and development because it provides key information for quantitative assessment of the pharmacodynamics, efficacy, and safety of the CTLA-4-based therapies. However, to our best knowledge, there is still no report of a sensitive, specific, accurate, and reliable assay for CTLA-4 measurement. In this work, an LC/MS-based method was developed to measure CTLA-4 in human T cells. The assay demonstrated high specificity with an LLOQ of 5 copies of CTLA-4 per cell when using 2.5 million T cells for analysis. As shown in the work, the assay was successfully used to measure CTLA-4 levels in subtype T-cell samples from individual healthy subjects. The assay could be applied in supporting the studies of CTLA-4-based cancer therapies.

Fc-independent functions of anti-CTLA-4 antibodies contribute to anti-tumor efficacy.

Ipilimumab, a monoclonal antibody that recognizes cytotoxic T-lymphocyte associated protein 4 (CTLA-4), was the first immune checkpoint inhibitor approved by the FDA to treat metastatic melanoma patients. Multiple preclinical studies have proposed that Fc effector functions of anti-CTLA-4 therapy are required for anti-tumor efficacy, in part, through the depletion of intratumoral regulatory T cells (Tregs). However, the contribution of the Fc-independent functions of anti-CTLA-4 antibodies to the observed efficacy is not fully understood. H11, a non-Fc-containing single-domain antibody (VHH) against CTLA-4, has previously been demonstrated to block CTLA-4-ligand interaction. However, in vivo studies demonstrated lack of anti-tumor efficacy with H11 treatment. Here, we show that a half-life extended H11 (H11-HLE), despite the lack of Fc effector functions, induced potent anti-tumor efficacy in mouse syngeneic tumor models. In addition, a non-Fc receptor binding version of ipilimumab (Ipi-LALAPG) also demonstrated anti-tumor activity in the absence of Treg depletion. Thus, we demonstrate that Fc-independent functions of anti-CTLA-4 antibodies contributed to anti-tumor efficacy, which may indicate that non-Treg depleting activity of anti-CTLA-4 therapy could benefit cancer patients in the clinic.

Supplemental Nutrition Assistance Program (SNAP)-authorized retailers received a low score using the Business Impact Assessment for Obesity and population-level nutrition (BIA-Obesity) tool.

BACKGROUND: The Supplemental Nutrition Assistance Program (SNAP) supports Americans with lower income to purchase dietary products at authorized retailers. This research aimed to evaluate SNAP-authorized retailers' public commitments in support of nutrition security and to examine differences between traditional grocers and nontraditional (e.g., convenience, drug, dollar) SNAP-authorized retailers' public commitments. METHODS: Prominent United States (U.S.) SNAP-authorized retailers nationally and in two U.S. states (California and Virginia) were identified based on number of store locations (n = 61). Public information available in grey literature were reviewed and scored using the Business Impact Assessment for Obesity and population-level nutrition (BIA-Obesity) tool. SNAP-authorized retailers were classified as traditional (e.g., grocery) or nontraditional (e.g., non-grocery) retailers. Total BIA-Obesity from 0 to 615, representing low to optimal support) and category scores were calculated for corporate strategy, relationships with external organizations, product formulation, nutrition labeling, product and brand promotion, and product accessibility. Descriptive statistics were used to describe BIA-Obesity scores overall and by category. Mann-Whitney U was used to test for potential differences in median BIA-Obesity total scores between traditional and nontraditional SNAP-authorized retailers (a priori, p < 0.05). RESULTS: Average total BIA-Obesity scores for SNAP-authorized retailers ranged from 0 to 112 (16.5 ± 23.3). Total BIA-Obesity scores for traditional SNAP-authorized retailers (32.7 ± 33.6; median 25) were higher than nontraditional SNAP-authorized retailer scores (11.2 ± 16; median 5) (p = 0.008). For BIA-Obesity categories, average scores were highest for the category relationships with external organizations (8.3 ± 10.3) and lowest for promotion practices (0.6 ± 2.1). CONCLUSIONS: Results of this research underscore a dearth of available evidence and substantial opportunity for improvement regarding SNAP-authorized retailer strategies to support nutrition security among Americans with lower income.

Direct and indirect freedom in addiction: Folk free will and blame judgments are sensitive to the choice history of drug users.

People view addiction as a source of diminished free will and moral responsibility. Yet, people are also sensitive to the personal histories of moral actors, including, perhaps, the way by which people became addicted. Across two studies (N = 806), we compare people's moral intuitions about cases in which the actor becomes addicted by force or by choice. We find that perceptions of reduced free will partially mediate an association between choice (vs. no choice) in addiction and moral blame for a bad act (Study 1). We replicate this pattern and show that blame judgments are stronger when the bad act is related (vs. unrelated) to obtaining the addictive substance (Study 2). Our work is novel in demonstrating that lay people evince relatively nuanced intuitions about the role of free will in addiction and morality-they track direct and indirect paths to choices when making free will and blame judgments.

Supplemental Nutrition Assistance Program (SNAP)-Authorized Retailers' Perceived Costs to Use Behavioral Economic Strategies to Encourage Healthy Product Sales.

SNAP-authorized retailers could use marketing-mix and choice-architecture (MMCA) strategies to improve SNAP purchases, but associated costs are unknown. Perceived cost and inconvenience to implement eight MMCA strategies were assessed among 29 U.S. retailers. Differences in perspective were explored (owners vs. managers, corporate vs. independent retailers, and by format). Place changes (e.g., added refrigeration) were perceived more costly and prompting (e.g., shelf labeling) less costly. Managers rated the perceived inconvenience to make proximity changes higher than owners (3.78 ± 1.4 and 2.33 ± 1.2, respectively) (p < .05). Results can inform strategies to improve the adoption and implementation of healthy food retail programs.

Pharmacokinetic Characterization and Tissue Distribution of Fusion Protein Therapeutics by Orthogonal Bioanalytical Assays and Minimal PBPK Modeling.

Characterization of pharmacokinetic (PK) properties and target tissue distribution of therapeutic fusion proteins (TFPs) are critical in supporting in vivo efficacy. We evaluated the pharmacokinetic profile of an investigational TFP consisting of human immunoglobulin G4 fused to the modified interferon alpha by orthogonal bioanalytical assays and applied minimal physiologically based pharmacokinetic (PBPK) modeling to characterize the TFP pharmacokinetics in mouse. The conventional ligand binding assay (LBA), immunocapture-liquid chromatography/tandem mass spectrometry (IC-LC/MS) detecting the human IgG4 peptide or the interferon alpha peptide were developed to measure the TFP concentrations in mouse plasma and tumor. The minimal PBPK model incorporated a tumor compartment model was used for data fitting. The plasma clearance measured by LBA and IC-LC/MS was comparable in the range of 0.5-0.6 mL/h/kg. However, the tumor exposure measured by the generic human IgG4 IC-LC/MS was significantly underestimated compared with the interferon alpha specific IC-LC/MS and LBA. Furthermore, the minimal PBPK model simultaneously captured the relationship between plasma and tissue exposure. We proposed the streamlined practical strategy to characterize the plasma exposure and tumor distribution of a TFP by both LBA and IC-LC/MS. The minimal PBPK modeling was established for better understanding of pharmacokinetic profile of investigational TFPs in the biotherapeutic discovery.

An LC/MS based method to quantify DNA adduct in tumor and organ tissues.

Highly potent DNA damaging agents have become a key class of toxins for antibody-drug conjugate (ADC) based targeted therapy. However, until recently, no quantitative bioanalytical method was available to measure the toxin in the form of DNA adducts. In this work, a novel microwave assisted organic solvent extraction and LC-MS/MS based bioanalytical method was developed to extract and quantify DNA-bound toxin IGN-P1 in tissue samples. Using ADC-1 as the model ADC, the method was orthogonally checked with a radioactive method for the recovery of free toxins from DNA adducts in biological matrices. It was found that the bioanalytical method can achieve a high recovery of the IGN-P1 toxin from DNA adducts. In further assessment, tumor and organ tissue samples collected at multiple time points from in vivo studies after dosing with two other ADCs, ADC-2 and ADC-3, were measured by the method. Given the generic nature of the established bioanalytical method without the need of radiolabels, the methodology could be broadly utilized to quantitatively assess the relationship between DNA adduct levels and pharmacological/toxicological effects.

Psychometric evaluation of the Informed Consent Process Scale in Chinese.

BACKGROUND: Informed consent is essential for the ethical conduct of clinical research and is a culturally sensitive issue. But, a measurable Chinese version of the scale to evaluate the informed consent process has not yet been explored in the existing literature. RESEARCH OBJECTIVES: This study aimed to develop and psychometrically test the Chinese version of the Informed Consent Process Scale. RESEARCH DESIGN: Back-translation was conducted to develop the Chinese version of the questionnaire. A cross-sectional survey was administered, after which an exploratory factor analysis was conducted. PARTICIPANTS: We recruited a total of 375 participants who had experience in signing an informed consent form within the previous 3 years in Taiwan. ETHICAL CONSIDERATIONS: This study was approved by two Institutional Review Boards and the autonomy of the participants was respected. FINDINGS: The Chinese version of the Informed Consent Process Scale is composed of three factors with 23 items showing evidence of acceptable reliability and validity. Three major factors were extracted and labeled: Factor 1 - 'Understanding of the research', Factor 2 - 'Trust and confidence' and Factor 3 - 'Doubt and uncertainty'. The three factors accounted for is 52.954 of the total variance with Cronbach's α of .917. DISCUSSION AND CONCLUSION: The finding corroborates previous studies showing that participants had too little understanding on the informed consent forms they signed and implied the need to clarify the critical points in clinical research. The psychometric results indicated good internal consistency and validity for this newly constructed instrument, and it was found worthy of conducting further testing and application.

A Two-Step Immunocapture LC/MS/MS Assay for Plasma Stability and Payload Migration Assessment of Cysteine-Maleimide-Based Antibody Drug Conjugates.

Plasma stability assessment under physiological temperature is an essential step for developing and optimizing antibody drug conjugate (ADC) molecules, especially those with cleavable linkers. The assessment of plasma stability often requires monitoring multiple analytes using a combination of bioanalytical assays for free payloads, conjugated payloads (or conjugated antibodies), total antibodies, and payloads that have migrated from antibodies to plasma constituent proteins. Bioanalytical assays are needed in early drug discovery to quickly screen diverse ADC candidates of different antibody constructs, linker variants, and antibody anchor sites. To improve the sensitivity and selectivity of LC/MS/MS-based assays for the assessment, immunocapture has been widely used for extracting ADCs and unconjugated antibodies from plasma samples. In this study, a novel two-step immunocapture LC/MS/MS assay was described to allow the quantification of conjugated payloads, total antibodies, and migrated payloads forming adducts with albumin in the plasma samples for stability assessment. A target antigen immobilized on magnetic beads was used to exhaustively extract the ADC and antibody-associated species. The remaining supernatant was then extracted further with anti-albumin beads for recovering the albumin-associated adducts for quantification. The method was optimized for higher efficiency and cost-effectiveness using microwave enhanced papain-based enzymatic cleavage for measuring conjugated payloads of ADCs and lysyl endopeptidase cleavage in the total antibody assay. A maleimide linker-based ADC with a proprietary payload, TAK-001, was used to demonstrate the streamlined workflow of the ADC stability assessment. The method could provide valuable evaluation of the stability of the ADC as well as the quantitative assessment of the albumin adducts formed from the linker-payload migration in mouse and human plasma. Furthermore, the method should be readily adaptable for other ADCs using thiol-maleimide conjugation chemistry.

Immunocapture-LC/MS-Based Target Engagement Measurement in Tumor Plasma Membrane.

For targeted therapies, immunocapture-liquid chromatography mass spectrometry (IC-LC/MS) technology has become an important tool for determination of both drug exposures, target antigen densities, and engagement in the systemic circulation and/or in total target tissue homogenates. Although the information collected from the circulation and tissue homogenates is useful in establishing the correlations of the exposure and target engagement with the pharmacodynamic response and efficacy of a therapy, the measurement at the cell plasma membrane within the target tissue is preferred, since it is the primary action site for antigen and the target drug. However, to the best of our knowledge, IC-LC/MS-based methodologies to conduct the assays at the plasma membrane from tissue sample has been quite limited. In this paper, we reported an IC-LC/MS-based assay platform for assessing the target engagement in tumor plasma membrane prepared from the tumor tissue samples. In addition, tumor samples with guanylyl cyclase C (GCC) expression after fully human IgG1 monoclonal antibody-based antibody-drug conjugate (ADC) treatment were used as a case study. The methodology can differentiate between the total and target-drug bound fraction of GCC with minimal potential equilibrium shift between in-cell surface protein and organelle protein in tumor samples to calculate in vivo target engagement. This approach to determine in vivo target engagement in tumor plasma membrane will provide better understanding of pharmacokinetic/pharmacodynamic relationship to achieve the desired antitumor efficacy.

Efficacy of Targeted Complement Inhibition in Experimental C3 Glomerulopathy.

C3 glomerulopathy refers to renal disorders characterized by abnormal accumulation of C3 within the kidney, commonly along the glomerular basement membrane (GBM). C3 glomerulopathy is associated with complement alternative pathway dysregulation, which includes functional defects in complement regulator factor H (FH). There is no effective treatment for C3 glomerulopathy. We investigated the efficacy of a recombinant mouse protein composed of domains from complement receptor 2 (CR2) and FH (CR2-FH) in two models of C3 glomerulopathy with either preexisting or triggered C3 deposition along the GBM. FH-deficient mice spontaneously develop renal pathology associated with abnormal C3 accumulation along the GBM and secondary plasma C3 deficiency. CR2-FH partially restored plasma C3 levels in FH-deficient mice 2 hours after intravenous injection. CR2-FH specifically targeted glomerular C3 deposits, reduced the linear C3 reactivity assessed with anti-C3 and anti-C3b/iC3b/C3c antibodies, and prevented further spontaneous accumulation of C3 fragments along the GBM. Reduction in glomerular C3d and C9/C5b-9 reactivity was observed after daily administration of CR2-FH for 1 week. In a second mouse model with combined deficiency of FH and complement factor I, CR2-FH prevented de novo C3 deposition along the GBM. These data show that CR2-FH protects the GBM from both spontaneous and triggered C3 deposition in vivo and indicate that this approach should be tested in C3 glomerulopathy.

A combined-biomarker approach to clinical phenotyping renal dysfunction in heart failure.

BACKGROUND: Differentiating heart failure (HF) induced renal dysfunction (RD) from intrinsic kidney disease is challenging. It has been demonstrated that biomarkers such as B-type natriuretic peptide (BNP) or the blood urea nitrogen to creatinine ratio (BUN/creat) can identify high- vs low-risk RD. Our objective was to determine if combining these biomarkers could further improve risk stratification and clinical phenotyping of patients with RD and HF. METHODS AND RESULTS: A total of 908 patients with a discharge diagnosis of HF were included. Median values were used to define elevated BNP (>1296 pg/mL) and BUN/creat (>17). In the group without RD, survival was similar regardless of BNP and BUN/creat (n = 430, adjusted P = .52). Similarly, in patients with both a low BNP and BUN/creat, RD was not associated with mortality (n = 250, adjusted hazard ratio [HR] = 1.0, 95% confidence interval [CI] 0.6-1.6, P = .99). However, in patients with both an elevated BNP and BUN/creat those with RD had a cardiorenal profile characterized by venous congestion, diuretic resistance, hypotension, hyponatremia, longer length of stay, greater inotrope use, and substantially worse survival compared with patients without RD (n = 249, adjusted HR = 1.8, 95% CI 1.2-2.7, P = .008, P interaction = .005). CONCLUSIONS: In the setting of decompensated HF, the combined use of BNP and BUN/creat stratifies patients with RD into groups with significantly different clinical phenotypes and prognosis.

Automated non-stepwise preparation of bioanalytical calibration standards and quality controls using an ultra-low volume digitizing liquid dispenser.

RATIONALE: Stepwise preparation of calibration standards and quality controls (QCs) is one of the most routine and laborious steps in bioanalysis. An alternative non-contact dispenser using low picoliter digitized dispensing technology is evaluated for its application in non-stepwise preparation of calibration curve and QCs in bioanalysis. METHODS: Fluorescein was initially used to assess the accuracy and precision of dispense volumes with fluorescent measurement. Various concentrations of MX-1, an in-house proprietary small molecule compound, in neat solution and in dog plasma were prepared manually with calibrated pipettors and digitally by the digital dispenser. The plasma samples were extracted by protein precipitation. The resultant extracted samples and neat solutions of MX-1 were analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using an electrospray ionization (ESI) source in positive ion mode with selected reaction monitoring (SRM) of the mass transitions. RESULTS: In the three-day precision and accuracy assessment of dispensing volumes between 13 pL to 411.2 nL, the intra-day precision and accuracy ranged from 1.4% to 10.3% and -12.7% to 12.8%, respectively. The inter-day precision and accuracy ranged from 3.5% to 7.8% and -6.6% to 10.4%, respectively. For real analysis of in vivo study samples, all 49 samples analyzed showed a less than 5% difference between calibrations with digital and manual curve preparations. The resultant pharmacokinetic (PK) parameters were physiologically comparable as well. CONCLUSIONS: Using the digitized picoliter dispensing technology, high-speed automated precise and accurate dispense of a wide range of volumes can be achieved and tests for bioanalytical standards and QC preparations passed the stringent criteria set forth for regulated bioanalysis using LC/MS/MS-based technology. The digital dispenser has been found to be a useful tool in drug discovery for automatically preparing standards and QCs in seconds with low consumption of stock solutions and blank matrices.

DNA-guided assembly of biosynthetic pathways promotes improved catalytic efficiency.

Synthetic scaffolds that permit spatial and temporal organization of enzymes in living cells are a promising post-translational strategy for controlling the flow of information in both metabolic and signaling pathways. Here, we describe the use of plasmid DNA as a stable, robust and configurable scaffold for arranging biosynthetic enzymes in the cytoplasm of Escherichia coli. This involved conversion of individual enzymes into custom DNA-binding proteins by genetic fusion to zinc-finger domains that specifically bind unique DNA sequences. When expressed in cells that carried a rationally designed DNA scaffold comprising corresponding zinc finger binding sites, the titers of diverse metabolic products, including resveratrol, 1,2-propanediol and mevalonate were increased as a function of the scaffold architecture. These results highlight the utility of DNA scaffolds for assembling biosynthetic enzymes into functional metabolic structures. Beyond metabolism, we anticipate that DNA scaffolds may be useful in sequestering different types of enzymes for specifying the output of biological signaling pathways or for coordinating other assembly-line processes such as protein folding, degradation and post-translational modifications.

Diagnosis of closed injury and neoplasm of the brachial plexus by ultrasonography.

PURPOSE: To evaluate the feasibility and accuracy of high-frequency sonography (US) in diagnosing traumatic brachial plexus (BP) lesions and neoplasms in the adult. METHODS: Eleven patients with suspected BP closed trauma, 6 patients with BP neoplasm, and 12 healthy volunteers were scanned. The US findings were compared with surgical findings. RESULTS: The interscalene space and intervertebral foramina were useful anatomic markers in identifying the BP. In the 24 sites examined in the normal group (12 subjects examined on both sides), the fifth to seventh cervical nerve roots (C5-7, including upper and middle trunk) were seen, whereas the eighth cervical and first thoracic nerve roots (C8, T1, including the lower trunk) were seen in 91.7% (22/24) of the subjects. The BP appeared as three or four discrete rounded hypoechoic nodules between the anterior scalene and middle scalene muscle in transverse views at the C5-7 level, representing the trunks in the sagittal oblique section. In the BP trauma group (n = 11), the normal nerve trunk was interrupted, and lesions were shown as thickening and swelling with indistinct inner structures. In the neoplasm group (n = 6), masses were shown as hypoechoic masses. CONCLUSIONS: High-frequency US is valuable in diagnosing BP closed injuries and neoplasms.

Obesity and fast food in urban markets: a new approach using geo-referenced micro data.

This paper presents a new method of assessing the relationship between features of the built environment and obesity, particularly in urban areas. Our empirical application combines georeferenced data on the location of fast-food restaurants with data about personal health, behavioral, and neighborhood characteristics. We define a 'local food environment' for every individual utilizing buffers around a person's home address. Individual food landscapes are potentially endogenous because of spatial sorting of the population and food outlets, and the body mass index (BMI) values for individuals living close to each other are likely to be spatially correlated because of observed and unobserved individual and neighborhood effects. The potential biases associated with endogeneity and spatial correlation are handled using spatial econometric estimation techniques. Our application provides quantitative estimates of the effect of proximity to fast-food restaurants on obesity in an urban food market. We also present estimates of a policy simulation that focuses on reducing the density of fast-food restaurants in urban areas. In the simulations, we account for spatial heterogeneity in both the policy instruments and individual neighborhoods and find a small effect for the hypothesized relationships between individual BMI values and the density of fast-food restaurants.

Myosin ATP turnover rate is a mechanism involved in thermogenesis in resting skeletal muscle fibers.

Thermogenesis by resting muscle varies with conditions and plays an active role in homeostasis of body weight. The low metabolic rate of living resting muscles requires that ATP turnover by myosin be inhibited relative to the purified protein in vitro. This inhibition has not been previously seen in in vitro systems. We used quantitative epifluorescence microscopy of fluorescent nucleotides to measure single nucleotide turnovers in relaxed, permeable skeletal muscle fibers. We observed two lifetimes for nucleotide release by myosin: a fast component with a lifetime of approximately 20 s, similar to that of purified myosin, and a slower component with a lifetime of 230 +/- 24 s. We define the latter component to be the "super relaxed state." The fraction of myosins in the super relaxed state was decreased at lower temperatures, by substituting GTP for ATP or by increased levels of myosin phosphorylation. All of these conditions have also been shown to cause increased disorder in the structure of the thick filament. We propose a model in which the structure of the thick filament modulates the nucleotide turnover rates of myosin in relaxed fibers. Modulation of the relative populations of the super relaxed and conventional relaxed states could have a profound effect on muscle thermogenesis, with the capacity to also significantly alter whole-body metabolic rate.