The receptor for advanced glycation end products, RAGE, is a protein receptor localized on the cellular plasma membrane which binds to various ligands such as AGEs or HMGB1. RAGE activates downstream inflammatory signaling associated with diabetes and atherosclerosis. Our recent studies suggest heparan sulfate, a negatively charged linear polysaccharide, directly interacts with RAGE to promote receptor signaling and oligomerization. The objective of this study is to characterize the structural details of RAGE-heparan sulfate interactions and RAGE oligomerization. Site directed mutagenesis, heparin sepharose chromatography, and filter binding assays shows that basic residues on the V domain (K39, K43, K44, R104, and K107) and C1 domain (R216 and R218) of RAGE are essential for binding to heparin and heparan sulfate. Gel filtration chromatography demonstrated heparin-derived oligosaccharides with a minimal length of a dodecasaccharide (12-mer) are capable of inducing a stable tetramer of RAGE. Further testing suggests the tetramer complex consists of four RAGE monomers with two dodecasaccharides. A second site directed mutagenesis study identifies a patch of hydrophobic residues on the V domain (V35, V78-L79 and F85-V86) affecting RAGE oligomerization. Our findings show critical residues important for heparan sulfate binding and a subset of hydrophobic binding residues necessary for RAGE oligomerization. The construction of a preliminary crystal structure of RAGE with heparin-derived oligosaccharide is in progress. Lastly, the heparan sulfate and hydrophobic binding surface of RAGE appears to be separate from its ligand binding surface based on a ligand binding assay. Thus, understanding these RAGE-heparan sulfate interactions could lead to the development of pharmacological agents reducing the progression of certain pathological conditions in cardiovascular diseases and diabetes

Background

The rapid proliferation of electronic health records (EHRs) in clinics has had mixed impact on patient-centered communication, yet few evaluated interventions exist to train practicing providers in communication practices.

Aims

We extended the evidence-based Physician Asthma Care Education (PACE) program with EHR-specific communication strategies, and tested whether training providers with the extended program (EHR-PACE) would improve provider and patient perceptions of provider communication skills and asthma outcomes of patients.

Method

A pilot randomized design was used to compare EHR-PACE with usual care. Participants were providers ( n = 18) and their adult patients with persistent asthma ( n = 126). Outcomes were assessed at baseline and 3- and 6-month postintervention, including patient perception of their provider's communication skills and provider confidence in using EHRs during clinical encounters.

Results

Compared with the control group, providers who completed the EHR-PACE program reported significant improvements at 3-month follow-up in their confidence with asthma counseling practices (estimate 0.90, standard error [ SE] 0.4); p < .05) and EHR-specific communication practices (estimate 2.3, SE 0.8; p < .01), and at 6-month follow-up, a significant decrease in perception that the computer interferes with the patient-provider relationship (estimate -1.0, SE 0.3; p < .01). No significant changes were observed in patient asthma outcomes or their perception of their provider's communication skills.

Discussion

Training providers with skills to accommodate EHR use in the exam room increases provider confidence and their perceived skills in maintaining patient-centered communications in the short term.

Conclusion

Evidence-supported training initiatives that can increase capacity of busy providers to manage increased computing demands shows promise. More research is needed to fully evaluate EHR-PACE on patients' health status and their perceptions of their provider's care through a large-scale trial.

Anthropogenic water management can change surface energy budgets and the water cycle. In this study, we focused on impacts of Asian low-latitude irrigation on regional and global climates during boreal wintertime. A state-of-the-art Earth system model is used to simulate the land-air interaction processes affected by irrigation and the consequent responses in atmospheric circulation. Perturbed experiments show that wet soil moisture anomalies at low latitudes can reduce the surface temperature on a continental scale through atmospheric feedback. The intensity of prevailing monsoon circulation becomes stronger because of larger land-sea thermal contrast. Furthermore, anomalous upper level convergence over South Asia and midlatitude climatic changes indicate tropical-extratropical teleconnections. The wintertime Aleutian low is deepened and an anomalous warm surface temperature is found in North America. Previous studies have noted this warming but left it unexplained, and we provide plausible mechanisms for these remote impacts coming from the irrigation over Asian low-latitude regions. Key Points Model simulation without considering irrigation underestimates ET over Indo-Gangetic Plain Irrigation at Asian low latitudes has the potential to induce PNA teleconnection Irrigation results in interhemispheric thermal gradient, thereby modifying Pacific subtropical jet

Appropriate counseling of patients with autoimmune connective tissue disorders (ACTDs) is often challenging for radiation oncologists, especially regarding anticipated side-effects of radiation treatment. These patients can have highly variable and unpredictable sequelae from radiation therapy, and the uncertainty builds when radiation is convoluted by the addition of concurrent chemotherapy. While many patients may experience a mild intensification of toxicity above what is expected, some patients experience much more severe toxicity. These patients become critical learning cases, enabling a better understanding of the delicate and complex ways in which radiation response is altered in the context of ACTDs while allowing other patients with similar ACTD profiles to benefit from past experience. Our report makes an important contribution to this space by describing a particularly severe case of toxicity that manifested in such a patient and the ensuing clinical decision-making. Comprehensive genotyping of classic pharmacokinetic and pharmacodynamic pathway genes (including mutations in DPD and CDA) did not reveal any signatures that might explain her enhanced toxicity and we demonstrate that severe toxicity can still manifest in the era of modern conformal radiation treatments for rectal cancer. We urge caution in the treatment of patients with rare ACTDs, but also emphasize that curative treatment should not be withheld in such patients. We conclude by advocating for the development and maintenance of a prospective multiinstitutional database of patients with ACTDs to help inform and improve future practice.

Background

The medial prefrontal cortex (mPFC) plays an important role in depression and addiction. Previous studies have shown alterations in glutamatergic activity in the mPFC following the administration of ketamine in patients with depression and healthy controls. However, it remains unclear whether chronic, nonmedical use of ketamine affects metabolites in the mPFC.

Methods

Using proton magnetic resonance spectroscopy, we measured metabolites (glutamate and glutamine [Glx]; phosphocreatine and creatine [PCr+Cr]; myo-inositol; N-acetyl-aspartate; and glycerophosphocholine and phosphocholine [GPC+PC]) in the mPFC of chronic ketamine users (n = 20) and healthy controls (n = 43). Among ketamine users, 60% consumed ketamine once per day or more, 10% consumed it every 2 days and 30% consumed it every 3 or more days. Using analysis of covariance, we evaluated between-group differences in the ratios of Glx:PCr+Cr, myo-inositol:PCr+Cr, N-acetyl-aspartate:PCr+Cr and GPC+PC:PCr+Cr.

Results

Chronic ketamine users showed significantly higher Glx:PCr+Cr ratios than healthy controls (median 1.05 v. 0.95, p = 0.008). We found no significant differences in myoinositol:PCr+Cr, N-acetyl-aspartate:PCr+Cr or GPC+PC:PCr+Cr ratios between the 2 groups. We found a positive relationship between N-acetyl-aspartate:PCr+Cr and Glx:PCr+Cr ratios in the healthy control group (R = 0.345, p = 0.023), but the ketamine use group failed to show such an association (ρ = 0.197, p = 0.40).

Limitations

The cross-sectional design of this study did not permit causal inferences related to higher Glx:PCr+Cr ratios and chronic ketamine use.

Conclusion

This study provides the first evidence that chronic ketamine users have higher glutamatergic activity in the mPFC than healthy controls; this finding may provide new insights relevant to the treatment of depression with ketamine.

Background

Cigarette smoking continues to be the leading cause of preventable morbidity and mortality in China and other countries. Previous studies have demonstrated gray matter loss in chronic smokers. However, only a few studies assessed the changes of white matter integrity in this group. Based on those previous reports of alterations in white matter integrity in smokers, the aim of this study was to examine the alteration of white matter integrity in a large, well-matched sample of chronic smokers and non-smokers.

Methodology/principal findings

Using in vivo diffusion tensor imaging (DTI) to measure the differences of whole-brain white matter integrity between 44 chronic smoking subjects (mean age, 28.0±5.6 years) and 44 healthy age- and sex-matched comparison non-smoking volunteers (mean age, 26.3±5.8 years). DTI was performed on a 3-Tesla Siemens scanner (Allegra; Siemens Medical System). The data revealed that smokers had higher fractional anisotropy (FA) than healthy non-smokers in almost symmetrically bilateral fronto-parietal tracts consisting of a major white matter pathway, the superior longitudinal fasciculus (SLF).

Conclusion/significance

We found the almost symmetrically bilateral fronto-parietal whiter matter changes in a relatively large sample of chronic smokers. These findings support the hypothesis that chronic cigarette smoking involves alterations of bilateral fronto-parietal connectivity.

The Diels-Alder cycloaddition is one of the most powerful approaches in organic synthesis and is often used in the synthesis of important pharmaceuticals. Yet, strictly controlling the stereoselectivity of the Diels-Alder reactions is challenging, and great efforts are needed to construct complex molecules with desired chirality via organocatalysis or transition-metal strategies. Nature has evolved different types of enzymes to exquisitely control cyclization stereochemistry; however, most of the reported Diels-Alderases have been shown to only facilitate the energetically favourable diastereoselective cycloadditions. Here we report the discovery and characterization of CtdP, a member of a new class of bifunctional oxidoreductase/Diels-Alderase, which was previously annotated as an NmrA-like transcriptional regulator. We demonstrate that CtdP catalyses the inherently disfavoured cycloaddition to form the bicyclo[2.2.2]diazaoctane scaffold with a strict α-anti-selectivity. Guided by computational studies, we reveal a NADP⁺/NADPH-dependent redox mechanism for the CtdP-catalysed inverse electron demand Diels-Alder cycloaddition, which serves as the first example of a bifunctional Diels-Alderase that utilizes this mechanism.

p-Hydroxymandelate oxidase (Hmo) is a flavin mononucleotide (FMN)-dependent enzyme that oxidizes mandelate to benzoylformate. How the FMN-dependent oxidation is executed by Hmo remains unclear at the molecular level. A continuum of snapshots from crystal structures of Hmo and its mutants in complex with physiological/nonphysiological substrates, products and inhibitors provides a rationale for its substrate enantioselectivity/promiscuity, its active-site geometry/reactivity and its direct hydride-transfer mechanism. A single mutant, Y128F, that extends the two-electron oxidation reaction to a four-electron oxidative decarboxylation reaction was unexpectedly observed. Biochemical and structural approaches, including biochemistry, kinetics, stable isotope labeling and X-ray crystallography, were exploited to reach these conclusions and provide additional insights.

The Y128F single mutant of p-hydroxymandelate oxidase (Hmo) is capable of oxidizing mandelate to benzoate via a four-electron oxidative decarboxylation reaction. When benzoylformate (the product of the first two-electron oxidation) and hydrogen peroxide (an oxidant) were used as substrates the reaction did not proceed, suggesting that free hydrogen peroxide is not the committed oxidant in the second two-electron oxidation. How the flavin mononucleotide (FMN)-dependent four-electron oxidation reaction takes place remains elusive. Structural and biochemical explorations have shed new light on this issue. 15 high-resolution crystal structures of Hmo and its mutants liganded with or without a substrate reveal that oxidized FMN (FMN_ox) possesses a previously unknown electrophilic/nucleophilic duality. In the Y128F mutant the active-site perturbation ensemble facilitates the polarization of FMN_ox to a nucleophilic ylide, which is in a position to act on an α-ketoacid, forming an N5-acyl-FMN_red dead-end adduct. In four-electron oxidation, an intramolecular disproportionation reaction via an N5-alkanol-FMN_red C'α carbanion intermediate may account for the ThDP/PLP/NADPH-independent oxidative decarboxylation reaction. A synthetic 5-deaza-FMN_ox cofactor in combination with an α-hydroxyamide or α-ketoamide biochemically and structurally supports the proposed mechanism.