Grass lignin: biosynthesis, biological roles, and industrial applications

Lignin is a phenolic heteropolymer found in most terrestrial plants that contributes an essential role in plant growth, abiotic stress tolerance, and biotic stress resistance. Recent research in grass lignin biosynthesis has found differences compared to dicots such as Arabidopsis thaliana. For example, the prolific incorporation of hydroxycinnamic acids into grass secondary cell walls improve the structural integrity of vascular and structural elements via covalent crosslinking. Conversely, fundamental monolignol chemistry conserves the mechanisms of monolignol translocation and polymerization across the plant phylum. Emerging evidence suggests grass lignin compositions contribute to abiotic stress tolerance, and periods of biotic stress often alter cereal lignin compositions to hinder pathogenesis. This same recalcitrance also inhibits industrial valorization of plant biomass, making lignin alterations and reductions a prolific field of research. This review presents an update of grass lignin biosynthesis, translocation, and polymerization, highlights how lignified grass cell walls contribute to plant development and stress responses, and briefly addresses genetic engineering strategies that may benefit industrial applications

Emotion avoidance and fear bradycardia in patients with borderline personality disorder and healthy controls

BACKGROUND AND OBJECTIVES: Exaggerated emotional reactivity is supposed to be essential in the etiology of borderline personality disorder (BPD). More specifically, models of defensive behavior would predict reduced freezing behavior -indicated by fear bradycardia-in response to threat. This study examined automatic fear bradycardia responses in BPD versus healthy controls and the role of emotion dysregulation, more specifically tendencies to avoid emotions. METHODS: Patients with BPD (n = 23) and healthy controls (n = 18) completed questionnaires and then watched neutral, pleasant and unpleasant pictures while heart rate was assessed. RESULTS: Emotion avoidance interacted with group: it was associated with distinct autonomic responses in healthy controls but not in BPD patients. Controls with lower emotion avoidance tendencies showed bradycardia in response to unpleasant pictures, while controls with higher emotion avoidance tendencies did not. BPD patients showed no bradycardia, irrespective of their emotion avoidance tendencies. LIMITATIONS: This study is limited by a small sample size. Comorbidity or medication intake were not controlled for. CONCLUSIONS: The results may suggest impaired automatic defense responses in BPD. Further understanding of the regulation of distress and defense responses might improve BPD treatment

Emotion avoidance and fear bradycardia in patients with borderline personality disorder and healthy controls

Background and objectives Exaggerated emotional reactivity is supposed to be essential in the etiology of borderline personality disorder (BPD). More specifically, models of defensive behavior would predict reduced freezing behavior –indicated by fear bradycardia-in response to threat. This study examined automatic fear bradycardia responses in BPD versus healthy controls and the role of emotion dysregulation, more specifically tendencies to avoid emotions. Methods Patients with BPD (n = 23) and healthy controls (n = 18) completed questionnaires and then watched neutral, pleasant and unpleasant pictures while heart rate was assessed. Results Emotion avoidance interacted with group: it was associated with distinct autonomic responses in healthy controls but not in BPD patients. Controls with lower emotion avoidance tendencies showed bradycardia in response to unpleasant pictures, while controls with higher emotion avoidance tendencies did not. BPD patients showed no bradycardia, irrespective of their emotion avoidance tendencies. Limitations This study is limited by a small sample size. Comorbidity or medication intake were not controlled for. Conclusions The results may suggest impaired automatic defense responses in BPD. Further understanding of the regulation of distress and defense responses might improve BPD treatment

The Effect of Glucagon-Like Peptide-1 Receptor Blockade on Glucagon-Induced Stimulation of Insulin Secretion

: Data from transgenic rodent models suggest that glucagon acts as an insulin secretagogue by signalling through the Glucagon-Like Peptide-1 Receptor (GLP1R) present on β-cells. However, its net contribution to physiologic insulin secretion in humans is unknown. To address this question, we studied non-diabetic individuals in 2 separate experiments. Each subject was studied on 2 occasions in random order. In the first experiment, during a hyperglycemic clamp, glucagon was infused at 0.4ng/kg/min, increasing by 0.2ng/kg/min every hour for 5 hours. On one day exendin-9,39 (300pmol/kg/min) was infused to block GLP1R, while on the other saline was infused. The insulin secretion rate (ISR) was calculated by nonparametric deconvolution from plasma concentrations of C-peptide. Endogenous glucose production (EGP) and glucose disappearance (Rd) were measured using the tracer-dilution technique. Glucagon concentrations, by design, did not differ between study days. Integrated ISR was lower during exendin-9,39 infusion (213 ± 26 vs. 191 ± 22 nmol per 5 hr, saline vs. exendin-9,39 respectively, p = 0.02). In the separate experiment, exendin-9,39 infusion, compared to saline infusion, also decreased the β-cell secretory response to a 1mg glucagon bolus. These data show that in non-diabetic humans, glucagon partially stimulates the β-cell through GLP1R

Synthesis of (V2/3Sc1/3)(2)AlC i-MAX phase and V2-xC MXene scrolls

We report the synthesis and characterization of a new laminated i-MAX phase, (V2/3Sc1/3)(2)AlC, with in-plane chemical ordering between the M-elements. We also present evidence for the solid solution (V2-xScx)(2)AlC, where x amp;lt;= 0.05. Chemical etching of the Al and Sc results in a two-dimensional (2D) MXene counterpart: V2-xC from the latter phase. Furthermore, etching with HF yields single-sheet MXene of flat morphology, while LiF + HCl gives MXene scrolls. We also show a 4x reduction in etching time for (V2-xScx)(2)AlC compared to V2AlC, suggesting that traces of Sc changes the phase stability, and make the material more susceptible to etching. The results show a path for improved control of MXene synthesis and morphology, which may be applicable also for other MAX/MXene systems.Funding Agencies|Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [EM16-0004]; Research Infrastructure Fellow program [RIF 14-0074]; Knut and Alice Wallenberg (KAW) FoundationKnut &amp; Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Swedish Research councilSwedish Research Council [642-2013-8020, 2016-04412]; [KAW 2015.0043]</p

Theoretical Analysis, Synthesis, and Characterization of 2D W1.33C (MXene) with Ordered Vacancies

Synthesis of delaminated 2D W1.33C (MXene) has been performed by selectively etching Al as well as Sc/Y from the recently discovered nanolaminated i-MAX phases (W2/3Sc1/3)(2)AlC and (W2/3Y1/3)(2)AlC. Both quaternary phases produce MXenes with similar flake morphology and with a skeletal structure due to formation of ordered vacancies. The measured O, OH, and F terminations, however, differ in amount as well as in relative ratios, depending on parent material, evident from X-ray photoelectron spectroscopy. These findings are correlated to theoretical simulations based on first-principles, investigating the W1.33C, and the effect of termination configurations on structure, formation energy, stability, and electronic structure. The theoretical results indicate a favored F-rich surface composition, though with a system going from insulating/semiconducting to metallic for different termination configurations, suggesting a high tuning potential of these materials. Additionally, free-standing W1.33C films of 2-4 mu m thickness and with up to 10 wt % polymer (PEDOT:PSS) were tested as electrodes in supercapacitors, showing capacitances up to 600 F cm(-3) in 1 M H2SO4 and high capacitance retention for at least 10000 cycles at 10 A g(-1). This is highly promising results compared to other W-based materials to date.Funding Agencies|Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [EM16-0004]; Knut and Alice Wallenberg (KAW) FoundationKnut &amp; Alice Wallenberg Foundation [RIF 14-0074]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; Swedish Research councilSwedish Research Council [642-2013-8020, 2016-04412]; [KAW 2015.0043]</p

Mesenchymal Stem/Stromal Cell-Derived Extracellular Vesicles Elicit Better Preservation of the Intra-Renal Microvasculature Than Renal Revascularization in Pigs with Renovascular Disease

Background: Percutaneous transluminal renal angioplasty (PTRA) confers clinical and mortality benefits in select ‘high-risk’ patients with renovascular disease (RVD). Intra-renal-delivered extracellular vesicles (EVs) released from mesenchymal stem/stromal cells (MSCs) protect the kidney in experimental RVD, but have not been compared side-by-side to clinically applied interventions, such as PTRA. We hypothesized that MSC-derived EVs can comparably protect the post-stenotic kidney via direct tissue effects. Methods: Five groups of pigs (n = 6 each) were studied after 16 weeks of RVD, RVD treated 4 weeks earlier with either PTRA or MSC-derived EVs, and normal controls. Single-kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were assessed in vivo with multi-detector CT, and renal microvascular architecture (3D micro CT) and injury pathways ex vivo. Results: Despite sustained hypertension, EVs conferred greater improvement of intra-renal microvascular and peritubular capillary density compared to PTRA, associated with attenuation of renal inflammation, oxidative stress, and tubulo-interstitial fibrosis. Nevertheless, stenotic kidney RBF and GFR similarly rose in both PTRA- and EV-treated pigs compared RVD + Sham. mRNA sequencing reveled that EVs were enriched with pro-angiogenic, anti-inflammatory, and antioxidants genes. Conclusion: MSC-derived EVs elicit a better preservation of the stenotic kidney microvasculature and greater attenuation of renal injury and fibrosis compared to PTRA, possibly partly attributed to their cargo of vasculo-protective genes. Yet, both strategies similarly improve renal hemodynamics and function. These observations shed light on diverse mechanisms implicated in improvement of post-stenotic kidney function and position EVs as a promising therapeutic intervention in RVD