Characterizing heterogeneous forest structure in ponderosa pine forests via UAS-derived structure from motion.

Increasingly, dry conifer forest restoration has focused on reestablishing horizontal and vertical complexity and ecological functions associated with frequent, low-intensity fires that characterize these systems. However, most forest inventory approaches lack the resolution, extent, or spatial explicitness for describing tree-level spatial aggregation and openings that were characteristic of historical forests. Uncrewed aerial system (UAS) structure from motion (SfM) remote sensing has potential for creating spatially explicit forest inventory data. This study evaluates the accuracy of SfM-estimated tree, clump, and stand structural attributes across 11 ponderosa pine-dominated stands treated with four different silvicultural prescriptions. Specifically, UAS-estimated tree height and diameter-at-breast-height (DBH) and stand-level canopy cover, density, and metrics of individual trees, tree clumps, and canopy openings were compared to forest survey data. Overall, tree detection success was high in all stands (F-scores of 0.64 to 0.89), with average F-scores > 0.81 for all size classes except understory trees (< 5.0 m tall). We observed average height and DBH errors of 0.34 m and - 0.04 cm, respectively. The UAS stand density was overestimated by 53 trees ha-1 (27.9%) on average, with most errors associated with understory trees. Focusing on trees > 5.0 m tall, reduced error to an underestimation of 10 trees ha-1 (5.7%). Mean absolute errors of bole basal area, bole quadratic mean diameter, and canopy cover were 11.4%, 16.6%, and 13.8%, respectively. While no differences were found between stem-mapped and UAS-derived metrics of individual trees, clumps of trees, canopy openings, and inter-clump tree characteristics, the UAS method overestimated crown area in two of the five comparisons. Results indicate that in ponderosa pine forests, UAS can reliably describe large- and small-grained forest structures to effectively inform spatially explicit management objectives.

Restoration and fuel hazard reduction result in equivalent reductions in crown fire behavior in dry conifer forests.

Over the past several decades, the management of historically frequent-fire forests in the western United States has received significant attention due to the linked ecological and social risks posed by the increased occurrence of large, contiguous patches of high-severity fire. As a result, efforts are underway to simultaneously reduce potential fire and fuel hazards and restore characteristics indicative of historical forest structures and ecological processes that enhance the diversity and quality of wildlife habitat across landscapes. Despite widespread agreement on the need for action, there is a perceived tension among scientists concerning silvicultural treatments that modify stands to optimally reduce potential fire behavior (fuel hazard reduction) versus those that aim to emulate historical forest structures and create structurally complex stands (restoration). In this work, we evaluated thinning treatments in the Black Hills National Forest that exemplify the extremes of a treatment continuum that ranges from fuel hazard reduction to restoration. The goal of this work was to understand how the differing three-dimensional stand structures created by these treatment approaches altered potential fire behavior. Our results indicate that restoration treatments created higher levels of vertical and horizontal structural complexity than the fuel hazard reduction treatments but resulted in similar reductions to potential crown fire behavior. There were some trade-offs identified as the restoration treatments created larger openings, which generated faster mean rates of fire spread; however, these increased spread rates did not translate to higher levels of canopy consumption. Overall, our results suggest that treatments can create vertical and horizontal complexity desired for restoration and wildlife habitat management while reducing fire hazard and that they can be used in concert with traditional fuel hazard reduction treatments to reduce landscape scale fire risk. We also provide some suggestions to land managers seeking to design and implement prescriptions that emulate historical structures and enhance forest complexity.

Pathologic gene network rewiring implicates PPP1R3A as a central regulator in pressure overload heart failure.

Heart failure is a leading cause of mortality, yet our understanding of the genetic interactions underlying this disease remains incomplete. Here, we harvest 1352 healthy and failing human hearts directly from transplant center operating rooms, and obtain genome-wide genotyping and gene expression measurements for a subset of 313. We build failing and non-failing cardiac regulatory gene networks, revealing important regulators and cardiac expression quantitative trait loci (eQTLs). PPP1R3A emerges as a regulator whose network connectivity changes significantly between health and disease. RNA sequencing after PPP1R3A knockdown validates network-based predictions, and highlights metabolic pathway regulation associated with increased cardiomyocyte size and perturbed respiratory metabolism. Mice lacking PPP1R3A are protected against pressure-overload heart failure. We present a global gene interaction map of the human heart failure transition, identify previously unreported cardiac eQTLs, and demonstrate the discovery potential of disease-specific networks through the description of PPP1R3A as a central regulator in heart failure.

Changes in Fasting and Prandial Gut and Adiposity Hormones Following Vertical Sleeve Gastrectomy or Roux-en-Y-Gastric Bypass: an 18-Month Prospective Study.

BACKGROUND: Vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB) produce substantial weight loss, both primarily through gastric restriction but with potentially different hormonal signaling. This prospective, observational study compared changes in gut-derived hormones in VSG, RYGB, and weight-stable participants at 6 and 18 months post-surgery. METHODS: Sixty-four obese, non-diabetic women, including 18 VSG, 23 RYGB, and 23 weight-stable controls completed assessments at baseline and 6 months, before and after consuming a mixed-nutrient meal; blood sampling occurred for 180 min post-meal. Fifty-one participants completed the 18-month outcome. Change from baseline in post-prandial area under the curve (over 180 min) for GLP-1, PYY3-36, ghrelin, and leptin was measured at 6 and 18 months post-surgery. RESULTS: At 18 months, VSG and RYGB participants lost a mean (±SEM) of 25.5 ± 2.3% and 34.2 ± 4.2% of initial weight, respectively (p < 0.156), which both differed (p < 0.001) from the +1.7 ± 1.0% gain in the control group. Fasting ghrelin declined significantly more in VSG than RYGB participants at both months 6 (p = 0.0199) and 18 (p = 0.0003). In response to the mixed-nutrient meal, GLP-1 and PYY3-36 demonstrated an exaggerated post-prandial response that was significantly greater in RYGB than VSG at 6 months (p < 0.0001 and p = 0.0062, respectively) but not 18 months (p = 0.0296 and p = 0.1210). CONCLUSIONS: VSG and RYGB both produced substantial weight losses at 18 months. The data suggest a role of gastrointestinal hormones as mediators of weight loss.

Changes in neural responsivity to highly palatable foods following roux-en-Y gastric bypass, sleeve gastrectomy, or weight stability: An fMRI study.

OBJECTIVE: This prospective, observational fMRI study examined changes over time in blood oxygen level dependent (BOLD) response to high- and low-calorie foods (HCF and LCF) in bariatric surgery candidates and weight-stable controls. METHODS: Twenty-two Roux-en-Y gastric bypass (RYGB) participants, 18 vertical sleeve gastrectomy (VSG) participants, and 19 weight-stable controls with severe obesity underwent fMRI before and 6 months after surgery/baseline. BOLD signal change in response to images of HCF vs. LCF was examined in a priori regions of interest. RESULTS: RYGB and VSG participants lost 23.6% and 21.1% of initial weight, respectively, at 6 months, and controls gained 1.0%. Liking ratings for HCF decreased significantly in the RYGB and VSG groups but remained stable in the control group. BOLD response in the ventral tegmental area (VTA) to HCF (vs. LCF) declined significantly more at 6 months in RYGB compared to control participants but not in VSG participants. Changes in fasting ghrelin correlated positively with changes in VTA BOLD signal in both RYGB and VSG but not in control participants. CONCLUSIONS: Results implicate the VTA as a critical site for modulating postsurgical changes in liking of highly palatable foods and suggest ghrelin as a potential substrate requiring further investigation.

GLP-1 plays a limited role in improved glycemia shortly after Roux-en-Y gastric bypass: a comparison with intensive lifestyle modification.

Rapid glycemic improvements following Roux-en-Y gastric bypass (RYGB) are frequently attributed to the enhanced GLP-1 response, but causality remains unclear. To determine the role of GLP-1 in improved glucose tolerance after surgery, we compared glucose and hormonal responses to a liquid meal test in 20 obese participants with type 2 diabetes mellitus who underwent RYGB or nonsurgical intensive lifestyle modification (ILM) (n = 10 per group) before and after equivalent short-term weight reduction. The GLP-1 receptor antagonist exendin(9-39)-amide (Ex-9) was administered, in random order and in double-blinded fashion, with saline during two separate visits after equivalent weight loss. Despite the markedly exaggerated GLP-1 response after RYGB, changes in postprandial glucose and insulin responses did not significantly differ between groups, and glucagon secretion was paradoxically augmented after RYGB. Hepatic insulin sensitivity also increased significantly after RYGB. With Ex-9, glucose tolerance deteriorated similarly from the saline condition in both groups, but postprandial insulin release was markedly attenuated after RYGB compared with ILM. GLP-1 exerts important insulinotropic effects after RYGB and ILM, but the enhanced incretin response plays a limited role in improved glycemia shortly after surgery. Instead, enhanced hepatic metabolism, independent of GLP-1 receptor activation, may be more important for early postsurgical glycemic improvements.

Attitudes about the safety and efficacy of bariatric surgery among patients with type 2 diabetes and a body mass index of 30-40 kg/m2.

BACKGROUND: Despite increasing awareness within the medical community about the benefits of bariatric surgery for type 2 diabetes mellitus (T2DM), little is known about patients' attitudes toward bariatric surgery as a treatment for T2DM. The objective of this study was to investigate the attitudes of individuals with T2DM and a body mass index of 30 to 40 kg/m(2) concerning bariatric surgery for the treatment of T2DM. METHODS: Patients identified from the Pennsylvania Integrated Clinical and Administrative Research Database (PICARD) were surveyed about perceptions of the safety profile and efficacy of bariatric surgery as a treatment for obesity and T2DM and their willingness to be randomly assigned to receive a surgical procedure. RESULTS: A total of 130 individuals of 513 (25.3%) responded. Respondents had a median (interquartile range) age of 58.0 (range 51.0-63.0) years and self-reported body mass index of 32.9 (range 30.9-35.2) kg/m(2). Roughly half (66 of 130) were female. Overall, only 20.3% of respondents had positive views of bariatric surgery, with few reporting that it is a safe (14.3%) and effective (28.5%) treatment for T2DM. Less than 20% of respondents were willing to be randomly assigned to undergo a surgical procedure for the treatment of diabetes (16.1%) or obesity (17.5%). CONCLUSIONS: Few obese individuals with T2DM who responded to the survey had positive views about bariatric surgery. Patients' concerns about the procedure's safety profile and efficacy must be addressed to improve the acceptability of bariatric surgery as well as the feasibility of randomized, controlled trials of bariatric surgery for these individuals.

Comparison of Bariatric Surgical Procedures for Diabetes Remission: Efficacy and Mechanisms.

Bariatric surgery induces a mean weight loss of 15-30% of initial body weight (depending on the procedure), as well as a 45-95% rate of diabetes remission. Procedures that induce greater weight loss are associated with higher rates of diabetes remission. Improvements in glucose homeostasis after bariatric surgery are likely mediated by a combination of caloric restriction (followed by weight loss) and the effects of altered gut anatomy on the secretion of glucoregulatory gut hormones.

Lifestyle modifications and surgical options in the treatment of patients with obesity and type 2 diabetes mellitus.

This article reviews recent developments in the behavioral and surgical treatment of obesity and type 2 diabetes mellitus (T2DM). Randomized controlled trials of comprehensive lifestyle-modification programs, which include dietary interventions, physical activity, and behavioral therapy, have shown weight losses of 7% to 10% of initial body weight within 4 to 6 months after treatment. These programs also reduce the likelihood of developing T2DM by 58% for individuals with impaired glucose tolerance. Long-term maintenance of these improvements requires continued implementation of the program diet, physical activity, and self-regulatory behaviors. This can be successfully facilitated by continued patient-provider contact, which is frequently delivered by phone, mail, email, or online. However, these benefits may have less impact on those with extreme obesity or more significant health problems. For these individuals, bariatric surgery may be a more appropriate treatment. Bariatric surgical procedures induce mean weight losses of 15% to 30% of initial body weight (depending on the procedure) within 2 years after surgery, as well as a 45% to 95% rate of diabetes remission. Familiarity with these developments can help physicians and patients to determine which combinations of behavioral, medical, and surgical interventions are appropriate for the treatment of obesity and T2DM.

Physicians' attitudes about referring their type 2 diabetes patients for bariatric surgery.

BACKGROUND: Despite increasing evidence about the beneficial effects of bariatric surgery, little is known about physicians' attitudes toward it as a treatment of type 2 diabetes. Our objective was to investigate physicians' attitudes about referring patients with type 2 diabetes for bariatric surgery. METHODS: Physicians were identified from the Pennsylvania Integrated Clinical and Administrative Research Database and other databases. Physicians at an academic medical center (n = 142) and community-based physicians (n = 197) in the Philadelphia area in specialties likely to treat type 2 diabetes were sent a survey about their perceptions of the safety and efficacy of bariatric surgery as a treatment for obesity and type 2 diabetes. RESULTS: Of the physicians, 93 returned the survey, for a combined response rate of 27.4%. Respondents reported having positive impressions of bariatric surgery as a treatment for obesity and type 2 diabetes (79.6% and 67.4%, respectively). Only 20.8% of respondents indicated that they would be likely to refer their patients with type 2 diabetes with a body mass index of 30-34.9 kg/m(2) to a randomized research trial of bariatric surgery. CONCLUSION: In general, physicians who treat patients with type 2 diabetes had favorable impressions about bariatric surgery as a treatment for obesity and type 2 diabetes. However, only a few were willing to refer their patients with type 2 diabetes and a body mass index of 30-34.9 kg/m(2) to randomized research trials of bariatric surgery. This reluctance to refer patients represents an important barrier to the successful completion of studies of the efficacy of bariatric surgery for those with type 2 diabetes and a body mass index <35 kg/m(2).

Identifying pollutant sources in tidally mixed systems: case study of fecal indicator bacteria from marinas in Newport Bay, southern California.

This study investigates the contribution of several marinas to fecal indicator bacteria impairment in Newport Bay, a regionally important tidal embayment in southern California. Three different fecal indicator bacteria groups were assayed, including total coliform, Escherichia coli, and enterococci bacteria, all measured using the IDEXX Colilert and Enterolert system. To document temporal variability in the fecal indicator bacteria signal, water column samples (n = 4132) were collected from two marinas over time scales ranging from hours to months. To document spatial variability of the fecal indicator bacteria signal, water column and sediment samples were collected from a number of sites (n = 11 to 36, depending on the study) in and around the two marinas, over spatial scales ranging from meters to kilometers. To identify the dominant temporal and spatial patterns in these data a statistical approach--Empirical Orthogonal Function analysis--was utilized. Finally, to clarify the transport pathways responsible for the observed temporal and spatial patterns, fecal indicator bacteria data were compared to simultaneous measurements of tidal flow, temperature, and salinity. The results of this field effort collectively implicate runoff--both dry weather runoff at sampling sites located near some storm drains and wet weather runoff at all sites--as a primary source of fecal indicator bacteria in the water column and subtidal sediments. The results and analysis presented here reinforce the growing body of evidence that management of fecal indicator bacteria impairment in the coastal waters of southern California will require developing long-term strategies for treating nonpoint sources of both dry weather and stormwater runoff.