Homocysteine stimulates NADPH oxidase-mediated superoxide production leading to endothelial dysfunction in rats

Elevation of blood homocysteine (Hcy) levels (hyperhomocysteinemia) is a risk factor for cardiovascular disorders. We previously reported that oxidative stress contributed to Hcy-induced inflammatory response in vascular cells. In this study, we investigated whether NADPH oxidase was involved in Hcy-induced superoxide anion accumulation in the aorta, which leads to endothelial dysfunction during hyperhomocysteinemia. Hyperhomocysteinemia was induced in rats fed a high-methionine diet. NADPH oxidase activity and the levels of superoxide and peroxynitrite were markedly increased in aortas isolated from hyperhomocysteinemic rats. Expression of the NADPH oxidase subunit p22 phox increased significantly in these aortas. Administration of an NADPH oxidase inhibitor (apocynin) not only attenuated aortic superoxide and peroxynitrite to control levels but also restored endothelium-dependent relaxation in the aortas of hyperhomocysteinemic rats. Transfection of human endothelial cells or vascular smooth muscle cells with p22 phox siRNA to inhibit NADPH oxidase activation effectively abolished Hcy-induced superoxide anion production, thus indicating the direct involvement of NADPH oxidase in elevated superoxide generation in vascular cells. Taken together, these results suggest that Hcy-stimulated superoxide anion production in the vascular wall is mediated through the activation of NADPH oxidase, which leads to endothelial dysfunction during hyperhomocysteinemia.     

Diverse Mesorhizobium bacteria nodulate native Astragalus and Oxytropis in arctic and subarctic areas in Eurasia

Rhizobia nodulating native Astragalus and Oxytropis spp. in Northern Europe are not well-studied. In this study, we isolated bacteria from nodules of four Astragalus spp. and two Oxytropis spp. from the arctic and subarctic regions of Sweden and Russia. The phylogenetic analyses were performed by using sequences of three housekeeping genes (16S rRNA, rpoB and recA) and two accessory genes (nodC and nifH). The results of our multilocus sequence analysis (MLSA) of the three housekeeping genes tree showed that all the 13 isolates belonged to the genus Mesorhizobium and were positioned in six clades. Our concatenated housekeeping gene tree also suggested that the isolates nodulating Astragalus inopinatus, Astragalus frigidus, Astragalus alpinus ssp. alpinus and Oxytropis revoluta might be designated as four new Mesorhizobium species. The 13 isolates were grouped in three clades in the nodC and nifH trees. ¹⁵N analysis suggested that the legumes in association with these isolates were actively fixing nitrogen.     

Macrocyclic α helical peptide therapeutic modality: A perspective of learnings and challenges

Macrocyclic α-helical peptides have emerged as a compelling new therapeutic modality to tackle targets confined to the intracellular compartment. Within the scope of hydrocarbon-stapling there has been significant progress to date, including the first stapled α-helical peptide to enter into clinical trials. The principal design concept of stapled α-helical peptides is to mimic a cognate (protein) ligand relative to binding its target via an α-helical interface. However, it was the proclivity of such stapled α-helical peptides to exhibit cell permeability and proteolytic stability that underscored their promise as unique macrocyclic peptide drugs for intracellular targets. This perspective highlights key learnings as well as challenges in basic research with respect to structure-based design, innovative chemistry, cell permeability and proteolytic stability that are essential to fulfill the promise of stapled α-helical peptide drug development.     

ATP potentiates the formation of AChR aggregate in the co-culture of NG108-15 cells with C2C12 myotubes

The role of adenosine 5'-triphosphate (ATP) and P2Y(1) nucleotide receptor in potentiating agrin-induced acetylcholine receptor (AChR) aggregation is being demonstrated in a co-culture system of NG108-15 cell, a mouse neuroblastoma X rat glioma hybrid cell line that resembles spinal motor neuron, with C2C12 myotube. In the co-cultures, antagonized P2Y(1) receptors showed a reduction in NG108-15 cell-induced AChR aggregation. Parallel to this observation, cultured NG108-15 cell secreted ATP into the conditioned medium in a time-dependent manner. Enhancement of ATP release from the cultured NG108-15 cells by overexpression of active mutants of small GTPases increased the aggregation of AChRs in co-culturing with C2C12 myotubes. In addition, ecto-nucleotidase was revealed in the co-culture, which rapidly degraded the applied ATP. These results support the notion that ATP has a role in directing the formation of post-synaptic apparatus in vertebrate neuromuscular junctions.     

An increased autophagic flux contributes to the anti-inflammatory potential of urolithin A in macrophages

Background

An extract of Phyllanthus muellerianus and its constituent geraniin have been reported to exert anti-inflammatory activity in vivo. However, orally consumed geraniin, an ellagitannin, shows low bioavailability and undergoes metabolization to urolithins by gut microbiota. This study aimed at comparing geraniin and urolithin A with respect to inhibition of M1 (LPS) polarization of murine J774.1 macrophages and shedding more light on possible underlying mechanisms.

Individual performance in relation to cytonuclear discordance in a northern contact zone between long‐toed salamander (Ambystoma macrodactylum) lineages

Cytonuclear discordance in contact zones between related lineages is common, with mitochondrial clines often being displaced from clines in nuclear allele frequency. Proposed explanations for such a pattern include adaptive introgression of mtDNA or a neutral wake of mtDNA being left behind following hybrid zone movement. However, studies investigating these hypotheses are rare. Our previous survey of genetic variation in the long‐toed salamander (Ambystoma macrodactylum) highlighted a potential case of cytonuclear discordance between two lineages in western Canada. Here, we use additional markers and samples to clarify the extent of this discordance. We simultaneously assess the feeding performance of individuals in a common environment to test for an association between mitotype and individual performance. The genetic results confirm a general pattern of cytonuclear discordance in the focal region. However, we also observed more limited introgression of a diagnostic nuclear marker. Intriguingly, although there were differences in individual performance associated with the transition between mitotypes, these differences were not fully explained by mitotype. Instead, the lowest performance was observed in individuals demonstrating the greatest mismatch between mtDNA and all nuclear markers, suggesting the potential for cytonuclear incompatibilities to be acting. These results highlight the complexity of understanding the causes and consequences of mtDNA introgression and cytonuclear discordance in contact zones.     

Enhancement of Early Cervical Cancer Diagnosis with Epithelial Layer Analysis of Fluorescence Lifetime Images

This work reports the use of layer analysis to aid the fluorescence lifetime diagnosis of cervical intraepithelial neoplasia (CIN) from H&E stained cervical tissue sections. The mean and standard deviation of lifetimes in single region of interest (ROI) of cervical epithelium were previously shown to correlate to the gold standard histopathological classification of early cervical cancer. These previously defined single ROIs were evenly divided into layers for analysis. A 10-layer model revealed a steady increase in fluorescence lifetime from the inner to the outer epithelial layers of healthy tissue sections, suggesting a close association with cellular maturity. The shorter lifetime and minimal lifetime increase towards the epithelial surface of CIN-affected regions are in good agreement with the absence of cellular maturation in CIN. Mean layer lifetimes in the top-half cervical epithelium were used as feature vectors for extreme learning machine (ELM) classifier discriminations. It was found that the proposed layer analysis technique greatly improves the sensitivity and specificity to 94.6% and 84.3%, respectively, which can better supplement the traditional gold standard cervical histopathological examinations.