Normative intercapillary distance and vessel density data in the temporal retina assessed by wide-field spectral-domain optical coherence tomography angiography

A limitation of conventional optical coherence tomography angiography (OCTA) is the limited field of view normally used in data acquisition. As the technology improves, larger fields of view that capture information away from the macular are being explored in order to provide an enhanced ability to detect pathology. However, normative measurements for important OCTA metrics like vessel density and intercapillary distance are not currently well-characterized in the peripheral retina. In this prospective study, we measured vessel density and intercapillary distance of the superficial vascular complex, ganglion cell layer plexus, and deep capillary plexus in montaged macular/temporal scans from 53 (33 men) healthy volunteers. Vessel density and intercapillary distance were also compared across different regions of the retina, including along arcs at separate distance from the fovea. Compared to the central macular region, the temporal retina had significantly lower vessel density, decreased thickness, and greater intercapillary distance in the superficial vascular complex, GCLP ganglion cell layer plexus, and deep capillary plexus (Wilcoxon rank sum test P < 0.001), with each of the plexuses examined here showing a general decrease in vessel density and an increase in intercapillary distance towards the temporal region. No significant difference was noted comparing corresponding vessel density and intercapillary distance regions above and below the macula, and multiple linear regression showed that age and intraocular pressure were not associated with vessel density and intercapillary distance in most models. Repeatability analysis reported as intraclass correlation coefficients demonstrated moderate to excellent reliability of vessel density and intercapillary distance in all OCTA layers. These results should help provide an enhanced baseline to help identify vascular pathology in the peripheral retina.     

An insight into the inhibitory selectivity of 4-(Pyrazol- 4-yl)-pyrimidines to CDK4 over CDK2

Revealing selectivity mechanism of cyclin-dependent kinases (CDK) and their inhibitors is an important issue to develop potential anticancer drugs. The substituted 4-(Pyrazol-4-yl)-pyrimidines are potent inhibitors of CDK4 but not of the highly homologous CDK2. In order to reveal the inhibitory selectivity of these inhibitors to CDK4 over CDK2, we select one of substituted 4-(Pyrazol-4-yl)-pyrimidines as a representative (marked as A1 hereunder) and perform molecular docking, molecular dynamics simulations and binding free energy analysis for CDK4/A1 and CDK2/A1, respectively. The electrostatic and van der Waals (vdW) interactions of the A1 inhibitor with CDK4/CDK2 are discussed. The computed binding free energies based on the MM-PBSA method are consistent with experimental bioactivity ranking of A1 inhibitor to CDK4/CDK2. On the other hand, the conformational characteristics of CDK2 and CDK4 induced by A1 inhibitor are analysed and revealed. Results demonstrate that the vdW interactions considerably contribute to binding of CDK4/CDK2 with A1 inhibitor and are similar in size. The hydrogen bonding between A1 inhibitor and CDK4/CDK2 is considerably favourable to the binding, in which the hydrogen bond between the NH group of the pyrazole group of A1 and the residue Asp158 of CDK4 plays a crucial role in inhibitory selectivity of A1 inhibitor to CDK4 over CDK2. The electrostatic interaction energy differences between the corresponding residues of CDK4/A1 and CDK2/A1 confirm the above inference. The conformational changes of CDK2 and CDK4 induced by A1 inhibitor influence the selectivity of A1 inhibitor to CDK4/CDK2.     

Dental pulp stem cell‐derived exosomes alleviate cerebral ischaemia‐reperfusion injury through suppressing inflammatory response

ObjectivesThe study aimed to determine whether dental pulp stem cell‐derived exosomes (DPSC‐Exos) exert protective effects against cerebral ischaemia‐reperfusion (I/R) injury and explore its underlying mechanism.Materials and MethodsExosomes were isolated from the culture medium of human DPSC. Adult male C57BL/6 mice were subjected to 2 hours transient middle cerebral artery occlusion (tMCAO) injury followed by 2 hours reperfusion, after which singular injection of DPSC‐Exos via tail vein was administrated. Brain oedema, cerebral infarction and neurological impairment were measured on day 7 after exosomes injection. Then, oxygen‐glucose deprivation–reperfusion (OGD/R) induced BV2 cells were studied to analyse the therapeutic effects of DPSC‐Exos on I/R injury in vitro. Protein levels of TLR4, MyD88, NF‐κB p65, HMGB1, IL‐6, IL‐1β and TNF‐α were determined by western blot or enzyme‐linked immunosorbent assay. The cytoplasmic translocation of HMGB1 was detected by immunofluorescence staining.ResultsDPSC‐Exos alleviated brain oedema, cerebral infarction and neurological impairment in I/R mice. DPSC‐Exos inhibited the I/R‐mediated expression of TLR4, MyD88 and NF‐κB significantly. DPSC‐Exos also reduced the protein expression of IL‐6, IL‐1β and TNF‐α compared with those of the control both in vitro and in vivo. Meanwhile, DPSC‐Exos markedly decreased the HMGB1 cytoplasmic translocation induced by I/R damage.ConclusionsDPSC‐Exos can ameliorate I/R‐induced cerebral injury in mice. Its anti‐inflammatory mechanism might be related with the inhibition of the HMGB1/TLR4/MyD88/NF‐κB pathway.     

XPC promotes MDM2-mediated degradation of the p53 tumor suppressor

Although ubiquitin receptor Rad23 has been implicated in bringing ubiquitylated p53 to the proteasome, how Rad23 recognizes p53 remains unclear. We demonstrate that XPC, a Rad23-binding protein, regulates p53 turnover. p53 protein in XPC-deficient cells remains ubiquitylated, but its association with the proteasome is drastically reduced, indicating that XPC regulates a postubiquitylation event. Furthermore, we found that XPC participates in the MDM2-mediated p53 degradation pathway via direct interaction with MDM2. XPC W690S pathogenic mutant is specifically defective for MDM2 binding and p53 degradation. p53 is known to become stabilized following UV irradiation but can be rendered unstable by XPC overexpression, underscoring a critical role of XPC in p53 regulation. Elucidation of the proteolytic role of XPC in cancer cells will help to unravel the detailed mechanisms underlying the coordination of DNA repair and proteolysis.     

A Robust Noninvasive Approach to Study Gut Microbiota Structure of Amphibian Tadpoles by Feces

The 16S rDNA amplicon high-throughput sequencing technique provides a robust and inexpensive approach to detect the gut microbiota of amphibians. Since different experimental protocols generate technical biases in drawing the gut microbiota profiles, the integrative analysis of gut microbiota produced by different studies must be performed with circumspection. In this study, we compared the efficacy of two DNA extraction methods(i.e., a phenol-chloroform method and TIANamp Stool DNA Kit) in describing intestinal and fecal bacterial communities of transplanted Asiatic toad(Bufo gargarizans) tadpoles. In terms of the DNA extraction quality(i.e., DNA purity and yield rate) and the consistency in between fecal and intestinal microbiota structures(i.e., α and β diversity indices), the phenol-chloroform method was more robust than this commercial stool kit in profiling gut microbiota of tadpoles with feces.     

Molecular cloning and characterization of human Aph2 gene, involved in AP-1 regulation by interaction with JAB1

A human Aph2 gene (hAph2) was identified and cloned from a human placenta cDNA library. Bioinformatics analysis revealed hAPH2 protein shares 96% identity with mouse APH2 and contains a zf-DHHC domain (148-210aa), which is always involved in protein-protein or protein-DNA interaction. Differential expression patterns of hAph2 mRNA were observed in normal human tissues. Yeast two-hybrid screening found another hAPH2-interacting protein JAB1. The zf-DHHC domain of hAPH2 and the C-terminal of JAB1 were confirmed to be critical for the interaction. Fused with GFP and expressed in COS-7, NIH/3T3 and SMMC-7721 cell lines, hAPH2 showed predominant distribution in the cytoplasm and co-localized with JAB1 around the nucleus. Furthermore, overexpression of hAPH2 could increase apoptosis of COS-7 cells and negatively regulate JAB1-induced activation of AP-1 in a concentration dependent manner. The expression level of c-jun was also down-regulated by overexpression of hAPH2 in COS-7 cells. These data showed some basic characterization and function of hAph2 (hAPH2), dependent or independent with JAB1.