Obesity is the major contributing factor for the increased prevalence of type 2 diabetes (T2D) in recent years. Sustained positive influx of lipids is considered to be a precipitating factor for beta ...cell dysfunction and serves as a connection between obesity and T2D. Importantly, fatty acids (FA), a key building block of lipids, are a double‐edged sword for beta cells. FA acutely increase glucose‐stimulated insulin secretion through cell‐surface receptor and intracellular pathways. However, chronic exposure to FA, combined with elevated glucose, impair the viability and function of beta cells in vitro and in animal models of obesity (glucolipotoxicity), providing an experimental basis for the propensity of beta cell demise under obesity in humans. To better understand the two‐sided relationship between lipids and beta cells, we present a current view of acute and chronic handling of lipids by beta cells and implications for beta cell function and health. We also discuss an emerging role for lipid droplets (LD) in the dynamic regulation of lipid metabolism in beta cells and insulin secretion, along with a potential role for LD under nutritional stress in beta cells, and incorporate recent advancement in the field of lipid droplet biology.
Obesity is the major contributing factor for the increased prevalence of type 2 diabetes (T2D) in recent years. Sustained positive influx of lipids is considered to be a precipitating factor for beta cell dysfunction and serves as a connection between obesity and T2D. Importantly, fatty acids (FA), a key building block of lipids, are a double‐edged sword for beta cells. FA acutely increase glucose‐stimulated insulin secretion through cell‐surface receptor and intracellular pathways. However, chronic exposure to FA, combined with elevated glucose, impair the viability and function of beta cells in vitro and in animal models of obesity (glucolipotoxicity), providing an experimental basis for the propensity of beta cell demise under obesity in humans.
Left ventricular assist devices (LVADs) have become integral to the treatment of advanced heart failure. Surgical bleeding is a known complication of LVAD placement but is most associated with ...intraperitoneal pump locations. Here we describe a case of massive postoperative hemorrhage secondary to erosion of an intrapericardial LVAD into an intercostal artery with an associated rib fracture.
The objective of this study was to determine the natural progression of popliteal artery aneurysms (PAAs) and clinical variables associated with their accelerated growth.
Retrospective chart review ...of 224 patients with encounters between January 2008 and May 2016 and with at least one PAA was conducted. From this group, 65 asymptomatic patients had either unilateral (n = 43) or bilateral (n = 22) PAAs that were observed for at least 1 year of medical management before intervention. We divided these aneurysms into two groups based on whether their overall growth rate was above or below the eventual mean. Aneurysm diameter was taken from duplex ultrasound and computed tomography angiography.
There were 87 aneurysms evaluated among 65 patients. Mean age at diagnosis was 70.9 years (standard deviation SD, 9.39 years), and 64 patients were male (98%); 50 (77%) were white and 7 (11%) were African American. The average body mass index was 27.69 (SD, 4.90). At or before initial diagnosis, 61 (94%) patients had a concomitant lower extremity or abdominal aortic aneurysm; 51 (78%) patients were current or former smokers; and 16 (25%) had atrial fibrillation. The average growth rate of all aneurysms was 1.22 mm/y (SD, 1.93 mm). The mean surveillance time from initial diagnosis to last follow-up or intervention was 3.12 years (SD, 1.66 years). Of 87 aneurysms, 25 (29%) were repaired; 18 (21%) were repaired because of size criteria, 2 (2%) because of symptom criteria (claudication or acute limb ischemia), and 5 (6%) because of both criteria. During our study window, 62 aneurysms (71%) remained asymptomatic or did not undergo an intervention. The mean initial diameter at diagnosis was 16.9 mm (SD, 5.32 mm). Within the study, 50 (57%) aneurysms presented with or developed mural thrombus. Univariate analysis identified larger initial diameter (19.2 vs 14.7 mm; P = .020), atrial fibrillation (35% vs 16%; P = .042), and mural thrombus (38% vs 20%; P < .001) as predictors of diameter expansion greater than the mean. Multivariable analysis of the significant univariate factors determined that only initial diameter (odds ratio, 5.53; P = .007) and the presence or development of mural thrombus (odds ratio, 4.00; P = .008) maintained significance.
Patients presenting with a PAA at 20 mm or >20 mm in diameter, presence of luminal thrombus, or atrial fibrillation may need to be observed at more frequent scanning intervals than those without these risk factors. Further studies are required to validate these predictive growth factors.
IntroductionScreening for coronary artery disease in patients being considered for kidney transplant is common to stratify morbidity and mortality risk, but the optimal strategy, and its impact on ...outcomes, remains unclear. Here we test the hypothesis that myocardial perfusion imaging (MPI) abnormalities, left ventricular ejection fraction (LVEF), or coronary artery calcium (CAC) score are associated with all-cause mortality in potential kidney transplant recipients at Emory University Hospital (EUH).MethodsIn a retrospective chart review, we assessed the relationship between patient demographics, single-photon emission MPI results, and CAC scoring with post-evaluation outcomes at 5 years in consecutive patients referred for pre-transplant stress testing at EUH in 2015. Mann-Whitney U and Chi-Square tests assessed between-group differences in continuous and categorical variables, respectively. Multivariate analysis was performed using logistic regression models.ResultsDuring the study period, 589 patients (mean age 54 years; SEM 0.512, 58% male, 65% African American) underwent MPI and 424 also underwent CAC scoring. Overall, 90 patients (15%) had abnormal MPI (defined as any fixed or reversible defect) and 54 (9%) died during follow up. Age (mean 53.2 years; SEM 0.533 vs. 57.7 years; SEM 1.73, p=0.008), previous coronary artery bypass graft (CABG) (2.06% vs. 7.41%, p=0.017), and myocardial infarction (MI) post-evaluation (4.11% vs. 18.5%, p<0.001) were associated with all-cause mortality. Age (p=0.032) and MI post-evaluation (p<0.001) remained significant in multivariate analysis. MPI abnormalities, LVEF, and CAC score were not associated with all-cause mortality.ConclusionsAge and MI post-evaluation are associated with increased mortality in potential kidney transplant recipients referred for stress testing at EUH. We found no association between MPI abnormalities, LVEF, or CAC score and all-cause mortality.
Recycled carbon fiber has historically proven challenging to integrate into composite manufacturing due in no small part to the low-density, randomly oriented, discontinuous fiber format that results ...from typical recycling. Discontinuous fiber requires the use of alternative technologies than those traditionally applied to continuous fiber (e.g., hand lay-up, winding). Extrusion compounding is one such applicable technology, but material transfer into the system requires alternative feeding equipment or the use of an altered procedure as trialed in this research. In this study, an injection molding compound for automotive applications was prepared with recycled carbon fiber and compared against an existing commercial compound. Input fibers and molded compound were evaluated for mechanical performance, while relevant variables such as compounded fiber alignment and aspect ratio were compared to the existing baseline material to confirm a like-for-like composite material structure. Analysis indicates that recycled fiber performs similarly to virgin fiber reinforcement, demonstrating that recycled fiber may be a viable drop-in replacement for short-fiber discontinuous applications.
Recycled carbon fiber has historically proven challenging to integrate into composite manufacturing due in no small part to the low-density, randomly oriented, discontinuous fiber format that results ...from typical recycling. Discontinuous fiber requires the use of alternative technologies than those traditionally applied to continuous fiber (e.g., hand lay-up, winding). Extrusion compounding is one such applicable technology, but material transfer into the system requires alternative feeding equipment or the use of an altered procedure as trialed in this research. In this study, an injection molding compound for automotive applications was prepared with recycled carbon fiber and compared against an existing commercial compound. Input fibers and molded compound were evaluated for mechanical performance, while relevant variables such as compounded fiber alignment and aspect ratio were compared to the existing baseline material to confirm a like-for-like composite material structure. Overall, analysis indicates that recycled fiber performs similarly to virgin fiber reinforcement, demonstrating that recycled fiber may be a viable drop-in replacement for short-fiber discontinuous applications.
The photosynthetic assimilation of CO2 in C4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the ...activity and kinetic properties of these enzymes are needed to accurately parameterize C4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are currently no published temperature responses of both Rubisco carboxylation and oxygenation kinetics from a C4 plant, nor are there known measurements of the temperature dependency of the PEPc Michaelis-Menten constant for its substrate HCO3 (-), and there is little information on the temperature response of plant CA activity. Here, we used membrane inlet mass spectrometry to measure the temperature responses of Rubisco carboxylation and oxygenation kinetics, PEPc carboxylation kinetics, and the activity and first-order rate constant for the CA hydration reaction from 10°C to 40°C using crude leaf extracts from the C4 plant Setaria viridis. The temperature dependencies of Rubisco, PEPc, and CA kinetic parameters are provided. These findings describe a new method for the investigation of PEPc kinetics, suggest an HCO3 (-) limitation imposed by CA, and show similarities between the Rubisco temperature responses of previously measured C3 species and the C4 plant S. viridis.
The concept of “enabling conditions” centers on conditions that facilitate approaches to addressing social and ecological challenges. Although multiple fields have independently addressed the concept ...of enabling conditions, the literature lacks a shared understanding or integration of concepts. We propose a more synthesized understanding of enabling conditions beyond disciplinary boundaries by focusing on the enabling conditions that influence the implementation of a range of environmental policies termed payments for ecosystem services (PES). Through an analysis of key literature from different disciplinary perspectives, we examined how researchers and practitioners refer to and identify enabling conditions within the context of PES. Through our synthesis, we identified 24 distinct enabling conditions organized within 4 broad themes: biophysical, economic, governance, and social-cultural conditions. We found that the literature coalesces around certain enabling conditions, such as strong ecosystem science and existing institutions, regardless of disciplinary background or journal audience. We also observed key differences in how authors perceive the direction of influence for property type, program objectives, and number of actors. Additionally, we noted an emphasis on the importance of the contextual nature of many enabling conditions that may cause certain conditions to have a disproportionate impact on successful implementation in some circumstances. Unraveling the relative importance of specific enabling conditions in diverse contexts remains a research frontier. Ultimately, no single disciplinary perspective is likely to provide all necessary insights for PES creation, and given the intertwined nature of enabling conditions, practitioners need to consider insights from multiple dimensions. Our work suggests opportunities to better connect diverse conversations through integration of concepts, a common vocabulary, and a synthetic framework.
Objective This study examines relationships between affect and sleep in youth with affective disorders using ecological momentary assessment (EMA). Methods Participants included 94 youth, ages 8-16 ...(M = 11.73, 53% female) years with an anxiety disorder only (n = 23), primary major depressive disorder (with and without a secondary anxiety diagnoses; n = 42), and healthy controls (n = 29). A cell phone EMA protocol assessed affect and actigraphy measured sleep. Results The patterns of bidirectional relationships between affect and sleep differed across diagnostic groups. Higher daytime positive affect and positive to negative affect ratios were associated with more time in bed during the subsequent night for youth with primary depression and less time in bed for youth with anxiety only. More time asleep was associated with more positive affect for both diagnostic groups the following day. Conclusions This relationship may be important to consider in the treatment of youth affective disorders.
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