Quantitative measurement of cell-surface displayed proteins based on split-GFP assembly.

BACKGROUND: Microbial cell surface display technology allows immobilizing proteins on the cell surface by fusing them to anchoring motifs, thereby endowing the cells with diverse functionalities. However, the assessment of successful protein display and the quantification of displayed proteins remain challenging. The green fluorescent protein (GFP) can be split into two non-fluorescent fragments, while they spontaneously assemble and emit fluorescence when brought together through complementation. Based on split-GFP assembly, we aim to: (1) confirm the success display of passenger proteins, (2) quantify the number of passenger proteins displayed on individual cells. RESULTS: In this study, we propose two innovative methods based on split-green fluorescent protein (split-GFP), named GFP1-10/GFP11 and GFP1-9/GFP10-11 assembly, for the purpose of confirming successful display and quantifying the number of proteins displayed on individual cells. We evaluated the display efficiency of SUMO and ubiquitin using different anchor proteins to demonstrate the feasibility of the two split-GFP assembly systems. To measure the display efficiency of functional proteins, laccase expression was measured using the split-GFP assembly system by co-displaying GFP11 or GFP10-11 tags, respectively. CONCLUSIONS: Our study provides two split-GFP based methods that enable qualitative and quantitative analyses of individual cell display efficiency with a simple workflow, thus facilitating further comprehensive investigations into microbial cell surface display technology. Both split-GFP assembly systems offer a one-step procedure with minimal cost, simplifying the fluorescence analysis of surface-displaying cells.

Development and application of a sensitive phosphonium-hydrazide oligosaccharide labelling reagent in capillary electrophoresis- electrospray ionization- mass spectrometry.

Glycosylation is one of the most ubiquitous post-translational modifications (PTM) of proteins. Although the ionization efficiency of native glycans is fairly low, with the assistance of chemical derivation strategies, mass spectrometry (MS) has been extensively used in glycomics because of its high sensitivity, accuracy, and speed. In this study, a novel glycan labelling reagent, (4-hydrazidebutyl) triphenylphosphonium bromide (P4HZD), with a permanent positive charge was developed. The comprehensive capabilities of P4HZD for MS analysis of oligosaccharides were evaluated in detail using maltodextrin as a standard. This labelling reagent can be used in common biological MS techniques such as matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry. The MS signal intensity of maltodextrin species could be enhanced up to 96-fold in MALDI-MS by labelling with P4HZD, making P4HZD favorable for MALDI-MS-based high-throughput screening of oligosaccharides. Moreover, P4HZD-labelled oligosaccharides with a degree of polymerization (DP) from 1 to 18 could be separated and analysed by capillary electrophoresis (CE) combined with positive ion mode ESI-MS. In comparison with a commercialized oligosaccharide tag, Girard's reagent P (GirP), P4HZD was more effective for enhancing the signal of oligosaccharides in the middle or higher mass range using both ESI and MALDI ion sources. Two biologics, immunoglobulin G 2 (IgG 2) and fusion protein (FP), were chosen as model complex biological samples to test the efficacy of detection and separation of oligosaccharides by MALDI-MS and CE-ESI-MS analysis with P4HZD labelling. The results indicated that P4HZD is a promising labelling reagent for the detection of oligosaccharides in complex biological samples. The tandem workflow combines the strengths of MALDI-MS and CE-ESI-MS to fulfil the analytical demands of high-throughput screening, while affording good separation.

The Microstructure and Electronic Properties of Yttrium Oxide Doped With Cerium: A Theoretical Insight.

Trivalent Cerium (Ce3+) doped Yttrium Oxide (Y2O3) host crystal has drawn considerable interest due to its popular optical 5d-4f transition. The outstanding optical properties of Y2O3:Ce system have been demonstrated by previous studies but the microstructures still remain unclear. The lacks of Y2O3:Ce microstructures could constitute a problem to further exploit its potential applications. In this sense, we have comprehensively investigated the structural evolutions of Y2O3:Ce crystals based on the CALYPSO structure search method in conjunction with density functional theory calculations. Our result uncovers a new rhombohedral phase of Y2O3:Ce with R-3 group symmetry. In the host crystal, the Y3+ ion at central site can be naturally replaced by the doped Ce3+, resulting in a perfect cage-like configuration. We find an interesting phase transition that the crystallographic symmetry of Y2O3 changes from cubic to rhombohedral when the impurity Ce3+ is doped into the host crystal. With the nominal concentration of Ce3+ at 3.125%, many metastable structures are also identified due to the different occupying points in the host crystal. The X-ray diffraction patterns of Y2O3:Ce are simulated and the theoretical result is comparable to experimental data, thus demonstrating the validity of the lowest energy structure. The result of phonon dispersions shows that the ground state structure is dynamically stable. The analysis of electronic properties indicate that the Y2O3:Ce possesses a band gap of 4.20 eV which suggests that the incorporation of impurity Ce3+ ion into Y2O3 host crystal leads to an insulator to semiconductor transition. Meanwhile, the strong covalent bonds of O atoms in the crystal, which may greatly contribute to the stability of ground state structure, are evidenced by electron localization function. These obtained results elucidate the structural and bonding characters of Y2O3:Ce and could also provide useful insights for understanding the experimental phenomena.

Combination of early constraint-induced movement therapy and fasudil enhances motor recovery after ischemic stroke in rats.

PURPOSE: Constraint-induced movement therapy (CIMT) is a promising technique for the recovery of upper extremity movement in chronic stroke patients. However, the effectiveness of its use in acute ischemia has not been confirmed. Myelin-associated inhibitors, which have upregulated functions in tissues affected by acute focal infarction, limit axonal regeneration via activation of the Rho-Rho-associated protein kinase (ROCK) pathway. The present study examined whether early CIMT combined with the ROCK inhibitor fasudil promotes motor recovery after acute ischemic stroke. MATERIALS AND METHODS: Rats were trained to perform the skilled-reach test and then subjected to middle cerebral artery occlusion (MCAO), producing a stroke affecting the preferred forelimb. Rats were assigned to one of four groups (N = 6/group): (nontreated) Control, CIMT, Fasudil, or CIMT+fasudil. CIMT and/or intraperitoneal infusion of fasudil were initiated 1 day postMCAO. Skilled reach and foot fault test data were collected once before and repeatedly over 4 weeks after the operation. Infarct volumes were calculated. RESULTS: All four groups showed similar forelimb impairment before treatment. The performance of CIMT alone group was similar to that of controls on both tests. Fasudil alone facilitated recovery in the foot-fault test, but not in the skilled-reach test. Rats in the CIMT+fasudil group demonstrated enhanced recovery in both tests, including better performance over time than the Fasudil group on the foot-fault test. Infarct size did not differ significantly between the groups. CONCLUSIONS: Early CIMT promotes motor recovery after acute ischemic stroke when it is administered with fasudil pharmacotherapy, but not without it.

[Correlation between power Doppler vascularity index and microvessel density in high-grade gliomas and adjacent edema].

OBJECTIVE: To investigate the correlation between power Doppler vascularity index (PDVI) and microvessel density (MVD) and evaluate the angiogenesis in high-grade gliomas and the adjacent edema in patients with glioma using intraoperative power Doppler ultrasound (PDUS) during gross total resection. METHODS: In 25 cases of high-grade gliomas undergoing gross total tumor resections, PDUS was performed intraoperatively and the regions of interest within the tumor and the adjacent edema were analyzed with Photoshop software to measure the tumoral and peritumoral blood flow quantified as PDVI. The tumoral and adjacent MVD were determined using immunohistochemical staining for CD34. The correlation between PDVI in the gliomas and the adjacent edema and MVD in the corresponding areas were analyzed using Spearman correlation test. RESULTS: The measurement of both PVDI and MVD revealed significant difference in vascularity between the gliomas and the adjacent edema (t=0.000, P<0.01), and PDVI was positively correlated to MVD measurement (r=0.7248 in the tumors and r=0.6608 in the adjacent edema). CONCLUSIONS: The difference in the vascularity between the tumor and adjacent edema allows their distinction by PDUS during operation for high-grade glioma. Intraoperative PDUS provides an accurate and reliable means for measuring vascularity in the glioma and the adjacent edema tissue.

[Donor peripheral stem cells infusion for the treatment of failure of platelet recovery after allogeneic hematopoietic stem cell transplantation].

OBJECTIVE: To study the safety and effect of G-CSF mobilized donor hematopoietic stem cells infusion (GPBSCI) as the therapy for the failure of platelet recovery after allogeneic hematopoietic stem cell transplantation. METHODS: The clinical data of 15 patients with acute or chronic leukemia undergoing GPBSCI 16 times, 9 males and 6 females, aged 33 (14 approximately 48), were retrospectively analyzed. RESULTS: The median number of mononuclear cells (MNC) from bone marrow was (4.21 +/- 1.91) x 10(8)/kg (1.50 x 10(8)/kg approximately 7.46 x 10(8)/kg). The median number of MNCs from peripheral blood was (3.27 +/- 1.40) x 10(8)/kg (1.13 x 10(8)/kg approximately 5.90 x 10(8)/kg). The median CD34+ count was (2.13 +/- 1.69) x 10(6)/kg (0.24 x 10(6)/kg approximately 5.67 x 10(6)/kg). All the patients had achieved white cell engraftment. 8 patients with primary failure of platelet recovery and 7 patients with secondary failure of platelet recovery received donor peripheral stem cells infusion. The median day of infusion was +113 days (43 approximately 384 days). The median number of infused mononuclear cells was (3.09 +/- 1.54) x 10(8)/kg (1.35 approximately 5.99) x 10(8)/kg. Only 1 patient had transfusion related GVHD. Clinical efficacy was seen in 9 patients (56.3%). The efficacy of infusion within 100 day after transplantation was 87.50%, significantly higher than that conducted 100 days after the transplantation (25.00%, P = 0.012). CONCLUSION: With minimal side effect, GPBSCI may be an effective strategy for the therapy of failure of platelet recovery.