An Inhibitor-Monitorable Single-Tube Duplex Quantitative Real-Time PCR Assay for the Detection of 'Candidatus Liberibacter asiaticus'.

Huanglongbing (HLB) is a citrus infectious disease caused by 'Candidatus Liberibacter' spp. Recently, it has begun to spread rapidly worldwide, causing significant losses to the citrus industry. Early diagnosis of HLB relies on quantitative real-time PCR assays. However, the PCR inhibitors found in the nucleic acid extracted from plant materials pose challenges for PCR assays because they may result in false-negative results. Internal standard (IS) can be introduced to establish a single-tube duplex PCR for monitoring the influence of the PCR inhibitor, but it also brings the risk of false-negative results because the amplification of IS may compete with the target. To solve this problem, we proposed a mutation-enhanced single-tube duplex PCR (mSTD-PCR) containing IS with mutant-type primers. By introducing the 3'-terminal mutation in the primer of IS to weaken its amplification reaction and its inhibition of 'Candidatus Liberibacter asiaticus' (CLas) detection, the sensitivity and quantitative accuracy of CLas detection will not be affected by IS. In evaluating the sensitivity of CLas detection using simulation samples, the mSTD-PCR showed consistent sensitivity at 25 copies per test compared with the single-plex CLas assay. The detection result of 30 leaves and 30 root samples showed that the mSTD-PCR could recognize false-negative results caused by the PCR inhibitors and reduce workload by 48% compared with the single-plex CLas assay. Generally, the proposed mSTD-PCR provides a reliable, efficient, inhibitor-monitorable, quantitative screening method for accurately controlling HLB and a universal method for establishing a PCR assay for various pathogens.

Inhomogeneity of the Backward Extruded NdFeB Ring Magnet Prepared from Amorphous Powders.

Back extrusion is an important process to prepare radially oriented NdFeB ring magnets. In this work, we fabricate the ring magnets using amorphous magnetic powders as the raw material. The microstructure, magnetic properties, corrosion resistance, and mechanical properties of the backward extruded magnet at different positions along the axial direction have been investigated, and the inhomogeneity of the magnet is clarified. The results showed that the grains in the middle region of the ring magnet exhibit a strong c-axis orientation, whereas the grains at the bottom and top regions are disordered with random orientation. The microstructure variation is related to the distribution of the grain boundary phase and the degree of grain deformation. Due to the microstructure difference, the magnetic properties, temperature stability, corrosion resistance, and mechanical properties in the middle region of the magnet are higher than those in the top and bottom regions. The exchange coupling between grains also varies in different regions, which is related to the grain size and grain boundary thickness. In addition, different Co element segregations were observed in different regions, which has a crucial effect on the Curie temperature and thermal stability of the magnet. The microstructure difference also leads to the variation of corrosion resistance and mechanical properties for the samples from different regions of the magnet. This work suggests that the amorphous powder can be used to directly prepare radially oriented ring magnets, and the inhomogeneity of the magnet should be fully understood.

Immunogenic Cell Death Enhances Immunotherapy of Diffuse Intrinsic Pontine Glioma: From Preclinical to Clinical Studies.

Diffuse intrinsic pontine glioma (DIPG) is the most lethal tumor involving the pediatric central nervous system. The median survival of children that are diagnosed with DIPG is only 9 to 11 months. More than 200 clinical trials have failed to increase the survival outcomes using conventional cytotoxic or myeloablative chemotherapy. Immunotherapy presents exciting therapeutic opportunities against DIPG that is characterized by unique and heterogeneous features. However, the non-inflammatory DIPG microenvironment greatly limits the role of immunotherapy in DIPG. Encouragingly, the induction of immunogenic cell death, accompanied by the release of damage-associated molecular patterns (DAMPs) shows satisfactory efficacy of immune stimulation and antitumor strategies. This review dwells on the dilemma and advances in immunotherapy for DIPG, and the potential efficacy of immunogenic cell death (ICD) in the immunotherapy of DIPG.

Endoscopic retrograde appendicitis therapy versus laparoscopic appendectomy versus open appendectomy for acute appendicitis: a pilot study.

BACKGROUND: An increasing number of studies have shown the merits of endoscopic retrograde appendicitis therapy (ERAT) in diagnosing and treating acute uncomplicated appendicitis. However, no related prospective controlled studies have been reported yet. Our aim is to assess the feasibility and safety of ERAT in the treatment of acute uncomplicated appendicitis. METHODS: In this open-label, randomized trial, participants were randomly allocated to the ERAT group, laparoscopic appendectomy (LA) group and open appendectomy (OA) group. The primary outcome was the clinical success rate of the treatment. Intention-to-treat analysis was used in the study. RESULTS: The study comprised of 99 patients, with 33 participants in each group. The clinical success rate was 87.88% (29/33), 96.97% (32/33) and 100% (33/33) in the ERAT, LA and OA group, respectively. In the ERAT group, 4 patients failed ERAT due to difficult cannulation. In LA group, 1 patient failed because of abdominal adhesion. There were no significant differences among the three treatment groups regarding the clinical success rate (P = 0.123). The median duration of follow-up was 22 months. There were no significant differences (P = 0.693) among the three groups in terms of adverse events and the final crossover rate of ERAT to surgery was 21.21% (7/33). CONCLUSION: ERAT can serve as an alternative and efficient method to treat acute uncomplicated appendicitis. Trial registration The study is registered with the WHO Primary Registry-Chinese Clinical Trial Registry (ChiCTR1900025812).

An encodable multiplex microsphere-phase amplification sensing platform detects SARS-CoV-2 mutations.

SARS-CoV-2 variants of concern (VOCs) contain several single-nucleotide variants (SNVs) at key sites in the receptor-binding region (RBD) that enhance infectivity and transmission, as well as cause immune escape, resulting in an aggravation of the coronavirus disease 2019 (COVID-19) pandemic. Emerging VOCs have sparked the need for a diagnostic method capable of simultaneously monitoring these SNVs. To date, no highly sensitive, efficient clinical tool exists to monitor SNVs simultaneously. Here, an encodable multiplex microsphere-phase amplification (MMPA) sensing platform that combines primer-coded microsphere technology with dual fluorescence decoding strategy to detect SARS-CoV-2 RNA and simultaneously identify 10 key SNVs in the RBD. MMPA limits the amplification refractory mutation system PCR (ARMS-PCR) reaction for specific target sequence to the surface of a microsphere with specific fluorescence coding. This effectively solves the problem of non-specific amplification among primers and probes in multiplex PCR. For signal detection, specific fluorescence codes inside microspheres are used to determine the corresponding relationship between the microspheres and the SNV sites, while the report probes hybridized with PCR products are used to detect the microsphere amplification intensity. The MMPA platform offers a lower SARS-CoV-2 RNA detection limit of 28 copies/reaction, the ability to detect a respiratory pathogen panel without cross-reactivity, and a SNV analysis accuracy level comparable to that of sequencing. Moreover, this super-multiple parallel SNVs detection method enables a timely updating of the panel of detected SNVs that accompanies changing VOCs, and presents a clinical availability that traditional sequencing methods do not.

DCA increases the antitumor effects of capecitabine in a mouse B16 melanoma allograft and a human non-small cell lung cancer A549 xenograft.

PURPOSE: Capecitabine is one of the few chemotherapy drugs with high oral availability. Recently, sodium dichloroacetate (DCA) has shown great potential as an anticancer agent. In the present study, we assessed the anticancer effect of DCA in combination with capecitabine for cancers that modestly expressed TP. METHODS: A mouse B16 melanoma allograft and a human non-small cell lung cancer A549 xenograft were used to assess the effect of DCA and capecitabine combined treatment. Histology and immunohistochemistry were used to detect the apoptosis and proliferation of cancer cells. Real-time PCR and Western blot were carried out to detect the expression of TP and caspases, respectively. RESULTS: For the first time, we report that DCA increased the antitumor effects of capecitabine in a mouse B16 allograft and a human A549 xenograft by promoting apoptosis of tumor cells. DCA has little effect on the expression of TP. CONCLUSIONS: Our finding suggests that DCA in combination with capecitabine might be potential as a new therapeutic regimen against some cancers.

Effect of substitution of proline-77 to aspartate on the light-driven proton release of bacteriorhodopsin.

Wild-type bacteriorhodopsin (BR) and another retinal protein archaerhodopsin 4 (AR4) are both light-driven proton pumps, but exhibit opposite temporal orders of proton release and uptake upon a flash illumination at neutral pH due to a higher pK(a) of proton release complex (PRC) in AR4. Since the 77th residue in the extracellular side is proline (P) in BR, but aspartic acid (D) in AR4, we have mutated P77 in BR by D in this study. The new point mutation was found to affect the kinetics of proton release and the pH dependence significantly. Upon a flash excitation, three components "fast proton release,""proton uptake" and "slow proton release" were observed at neutral pH in P77D. The pK(a) of PRC in the M intermediate was increased from 5.6 in the wild-type to 7.0, and became closer to that in AR4, which is 8.4. The coupling strength between D85 and PRC were also weakened, as expected. These data indicate that the 77th residue in AR4 greatly account for the difference between the two proton pumps.

Ferritin light chain and squamous cell carcinoma antigen 1 are coreceptors for cellular attachment and entry of hepatitis B virus.

Overexpression of squamous cell carcinoma antigen 1 (SCCA1) in hepatitis G2 (HepG2) and Chinese hamster ovary cells can increase hepatitis B virus (HBV) binding capacity by interacting with the preS1 domain of the HBV surface antigen. However, the magnitude of increase in binding capacity was higher by several orders in the former, indicating the existence of additional factor(s) produced by HepG2 cells, which facilitates HBV attachment. Ferritin light chain (FTL) was identified as the sole high hit candidate by screening human liver cDNA library using a bacterial two-hybrid system with either preS or SCCA1 as the bait. Subsequent in vitro protein-protein interaction assays confirmed the binding activity of FTL to both preS and SCCA1, as well as the formation of triple complex preS-FTL-SCCA1, and narrowed down the binding sites on FTL. In vitro overexpression of FTL could further enhance HBV attachment in both HepG2 and Chinese hamster ovary cells, which were already overexpressing SCCA1. Importantly, in vivo co-expression of human FTL and SCCA1 in mouse liver by means of tailvein hydrodynamic injection increased serum levels of HBV surface antigen transiently 24 hours post challenge with HBV-positive human sera, and a large amount of HBV core antigen-positive hepatocytes around blood vessels could be identified by immunohistochemical staining 48 hours post challenge. The data strongly suggest that FTL and SCCA1 may serve as coreceptors in HBV cellular attachment and virus entry into hepatocytes.

Hydrophobic cavity in C-terminus is essential for hTNF-α trimer conformation.

A variety of tumour necrosis factor α (TNF-α) derivatives have been bioengineered to improve antitumour activity and reduce toxicity. The expression of TNF-α in Escherichia coli usually yields a mixture of homotrimers and monomers; however, only the trimer shows antitumour activity. TNF-αD10, a bioengineered hTNF-α derivative, demonstrated 10-fold higher cytotoxicity against tumour cells compared to hTNF-α, but the trimer to monomer ratio was 58:42. In the present study, we investigated the structural differences between the trimer and the monomer of TNF-αD10. We found that the chemical shifts of the C-terminal Trp(114) in the trimer were significantly different from those in the monomer and that the replacement of Trp(114) with different amino acids remarkably reduced the trimer production. Further analysis of the publicly available X-ray crystallographic data for trimeric and monomeric hTNF-α revealed that the conformation of the U-shaped region formed by the fragment Cys(101)-Trp(114) was different between the two forms: a hydrophilic cavity in the monomer and a hydrophobic cavity in the trimer. These findings suggested the potential approaches of molecular and structural modification for future improvement of hTNF-α trimer production.

High-dose siRNAs upregulate mouse Eri-1 at both transcription and posttranscription levels.

The eri-1 gene encodes a 3' exonuclease that can negatively regulate RNA interference via siRNase activity. High-dose siRNAs (hd-siRNAs) can enhance Eri-1 expression, which in return degrade siRNAs and greatly reduces RNAi efficiency. Here we report that hd-siRNAs induce mouse Eri-1 (meri-1) expression through the recruitment of Sp1, Ets-1, and STAT3 to the meri-1 promoter and the formation of an Sp1-Ets-1-STAT3 complex. In addition, hd-siRNAs also abolish the 3' untranslated region (UTR) mediated posttranscriptional repression of meri-1. Our findings demonstrate the molecular mechanism underlying the upregulation of meri-1 by hd-siRNA.

Effects of mutations of Lys41 and Asp102 of bacteriorhodopsin.

Bacteriorhodopsin (BR) is a retinal protein that functions as a light-driven proton pump. In this study, six novel mutants including K41E and D102K, were obtained to verify or rule out the possibility that residues Lys41 and Asp102 are determinants of the time order of proton release and uptake, because we found that the order was reversed in another retinal protein archaerhodopsin 4 (AR4), which had different 41th and 102th residues. Our results rule out that possibility and confirm that the pK(a) of the proton release complex (PRC) determines the time order. Nevertheless, mutations, especially D102K, were found to affect the kinetics of proton uptake substantially and the pK(a) of Asp96. Compared to the wild-type BR (BR-WT), the decay of the M intermediate and proton uptake in the photocycle was slowed about 3-fold in D102K. Hence those residues might be involved in proton uptake and delivery to the internal proton donor.

Severity of vanishing white matter disease does not correlate with deficits in eIF2B activity or the integrity of eIF2B complexes.

Autosomal recessive mutations in eukaryotic initiation factor 2B (eIF2B) cause leukoencephalopathy vanishing white matter with a wide clinical spectrum. eIF2B comprises five subunits (α-ε; genes EIF2B1, 2, 3, 4 and 5) and is the guanine nucleotide-exchange factor (GEF) for eIF2. It plays a key role in protein synthesis. Here, we have studied the functional effects of selected VWM mutations in EIF2B2-5 by coexpressing mutated and wild-type subunits in human cells. The observed functional effects are very diverse, including defects in eIF2B complex integrity; binding to the regulatory α-subunit; substrate binding; and GEF activity. Activity data for recombinant eIF2B complexes agree closely with those for patient-derived cells with the same mutations. Some mutations do not affect these parameters even though they cause severe disease. These findings are important for three reasons; they demonstrate that measuring eIF2B activity in patients' cells has limited value as a diagnostic test; they imply that severe disease can result from alterations in eIF2B function other than defects in complex integrity, substrate binding or GEF activity, and last, the diversity of functional effects of VWM mutations implies that seeking agents to manage or treat VWM should focus on downstream effectors of eIF2B, not restoring eIF2B activity.

Oren-gedoku-to and its constituents with therapeutic potential in Alzheimer's disease inhibit indoleamine 2, 3-dioxygenase activity in vitro.

A well-known traditional Chinese medicinal prescription, Oren-gedoku-to (OGT), has been used in clinical therapies for many types of dementia in China and Japan. Additionally, it ameliorates the age-related deterioration of learning and memory in an Alzheimer's disease (AD) rat model. Indoleamine 2, 3-dioxygenase (IDO-1) is the first and rate-limiting enzyme in the kynurenine pathway of tryptophan catabolism, which ultimately leads to the production of the excitotoxin quinolinic acid (QUIN). IDO-1 has recently been established as one of the key players involved in the pathogenesis of AD. OGT is indicated to prevent cholinergic dysfunction and reduce oxidative stress; however, the exact mechanism underlying its ability to improve cognitive ability remains elusive. Here we present a novel mechanism of OGT's therapeutic potential in AD. We demonstrated that OGT significantly inhibited recombinant human IDO-1 (rhIDO-1) activity in vitro, and its four main constituents (i.e., berberine, palmatine, jatrorrhizine, and baicalein) were potent IDO-1 inhibitors. IC50 values, obtained from a cell-based assay, of HEK 293 cells and an enzymatic assay were much lower than the most commonly used IDO-1 inhibitor, 1-methyl tryptophan (1-MT). Berberine was the best inhibitor and had IC50 values of 7 µM (cell-based assay) and 9.3 µM (enzymatic assay). Jatrorrhizine and palmatine exhibited irreversible inhibition of rhIDO-1, whereas berberine and baicalein behaved as uncompetitive, reversible inhibitors with Ki values of 8 µM and 215 µM, respectively. In conclusion, constituents of OGT show strong IDO-1 inhibitory activity and may have significant therapeutic potential for AD.

The role of VE-cadherin in osteosarcoma cells.

Osteosarcoma cells can generate vasculogenic-like, patterned networks to obtain nutrients and oxygen, which mimic some function of endothelial-like cells and facilitate tumor malignant progress. These cells also express vascular endothelial-cadherin (VE-cadherin), which is generally accepted as a strictly endothelial-specific transmembrane protein. However, its role is still relatively obscure in osteosarcoma cells. So we inhibit the VE-cadherin gene expression with siRNA in osteosarcoma cells (MG63), and culture those cells in three-dimensional medium, containing Type I collagen or Matrigel, to observe the role of VE-cadherin. Western blotting analysis show that sequence-specific siRNA can significantly decrease the expression of VE-cadherin in MG63 cell. After knockdown of VE-cadherin, osteosarcoma cells can't induced angiogenic sprout and form osteosarcoma-generated, endothelial-like networks. Our data indicate that VE-cadherin may be a positive and specific regulator not only in angiogenesis, but also in vasculogenic mimicry of osteosarcoma cells. And it can be considered as a new prospective option in the combining treatment of aggressive tumor with highly vascularity, including osteosarcoma.

Involvement of mitochondrial permeability transition in hepatitis B virus replication.

The HBx protein of human hepatitis B virus (HBV) activates a calcium-dependent kinase pathway which is essential for the viral replication. In this study, we found that HBx expression in the absence of other HBV proteins and in the context of HBV replication decreased the mitochondrial calcein-AM/CoCl(2) signals by 10% and 14% in HepG2 cells and by 15% and 10% in Huh7 cells, respectively. This indicates that HBx can induce mitochondrial permeability transition (MPT) and cause calcium effusion into the plasma. In addition, RNA interference of Cylophilin D decreased HBx-induced MPT and suppressed HBV DNA replication by 41% in HepG2 cells. Our results suggest that HBx expression can induce MPT and facilitate HBV DNA replication.

Isolation and functional expression of the bop gene from Halobiforma lacisalsi.

A novel bop gene was described from Halobiforma lacisalsi strain AJ5(T), an extremely halophilic archaeon isolated from Ayakekum Lake, China. Following six rounds of PCR amplification based on the conserved fragment of the bop gene, the complete sequence of the bop gene, including the 5' and 3' flanking regions of the conserved fragment, was obtained by the ligation-mediated PCR amplification (LPA) approach. The data presented provide us with further insight into the distribution of bop-like genes in the family Halobacteriaceae. This is the first example of a bop-like gene in halophiles found in the high-pH environment. Alignment and hydropathy analysis of the deduced amino acid sequence identified the conserved functional sites as well as some variations compared with other bacterio-opsins. Molecular phylogenetic analysis revealed the position of the bacterio-opsin of strain AJ5, which is closest to that of Haloterrigena sp. arg-4 with 85% identity. In the presence of all-trans retinal, recombinant Escherichia coli cells expressing the gene turned dark purple. The purple membrane from the recombinant E. coli showed maximal absorption at 540 nm.

Lentivirus-mediated short hairpin RNA targeting the APRIL gene suppresses the growth of pancreatic cancer cells in vitro and in vivo.

RNA interference (RNAi) is an evolutionarily conserved process of gene silencing in multiple organisms, which has become a powerful tool for investigating gene function by reverse genetics. Herein, we constructed a short hairpin RNA (shRNA) lentiviral expression vector targeting a proliferation-inducing ligand (APRIL) gene in the CFPAC-1 cell (a type of cell strain of human pancreatic cancer) in order to observe the inhibitory effect of APRIL gene's shRNA on the growth of the CFPAC-1 cell in vitro and in vivo. The results showed that lentivirus-mediated RNAi effectively inhibited the expression of APRIL mRNA and protein in CFPAC-1 cells. Moreover, it can inhibit the growth of pancreatic cancer cells in vitro and in vivo. Our study indicates that lentivirus-mediated gene therapy is an attractive strategy in the treatment of pancreatic cancer and justifies the use of lentivirus in cancer gene therapy studies.

esiRNA to eri-1 and adar-1 genes improving high doses of c-myc-directed esiRNA effect on mouse melanoma growth inhibition.

Knockdown of c-myc expression via RNAi is expected to be an efficient approach to suppress tumor growth. In our preliminary study, we intraperitoneally injected different doses of c-myc-directed esiRNA (esic-MYC, c-myc-directed Escherichia coli expressed and enzyme digested siRNA) into C57BL6/6J mice with bearing B16 melanoma to investigate the inhibitory effect of esic-MYC on tumor growth. However, in high dose esic-MYC treatment groups, the tumor growth inhibition was less efficient than that of low dose treatment groups. Considering the negative regulation roles of eri-1 and adar-1 genes in RNA interference, we downregulated either/both of the two genes with c-myc gene by RNAi. Our results showed esiMERI-1 (esiRNA of mouse eri-1 gene) and esiMADAR-1 (esiRNA of mouse adar-1 gene) could rescue the tumor growth suppression in the high dose esic-MYC treatment groups obviously. The data strongly suggest that silencing of eri-1 and adar-1 homologs of human being should be concerned for cancer therapy by RNAi approach.

A 14-mer peptide from HSP70 protein is the critical epitope which enhances NK activity against tumor cells in vivo.

Heat shock protein 70 (Hsp70) has been found to play key roles in tumor immunity due its chaperone function of binding antigenic peptides. Here we report it can also stimulate NK cells in vivo, which is another role in Hsp70s' anti-tumor response. Injecting Hsp70 into mice increased splenic NK cell populations, which may be reason for anti-tumor effect of Hsp70. The Hsp70 14-mer peptide (aa450-463, TRD) was identified as the critical epitope for this stimulatory activity. It was the murine Hsp70 14-mer peptide TRD instead of the corresponding human Hsp70 14-mer peptide TKD that functioned in the mouse experimental model.

RNA interference against hepatitis B virus with endoribonuclease-prepared siRNA despite of the target sequence variations.

RNA interference (RNAi) has proven to be very powerful in inhibiting hepatitis B virus (HBV) replication by cell culture and mouse model studies. We have previously reported that endoribonuclease-prepared short interfering RNAs (esiRNAs) were able to inhibit HBV replication more efficiently than synthesized siRNAs. Here we tested the hypothesis that esiRNAs are able to inhibit gene expression with limited mutations within the target region. Target sequences with different similarities to esiHBVP (esiRNA targeting the DNA polymerase and S antigen of Hepatitis B virus) were amplified and cloned into the 3' untranslated region of HBsAg, respectively. When the obtained expression vectors were co-transfected with esiHBVP into CHO cells, HBsAg expression was suppressed with same efficiency regardless of the target sequence similarities. In HepG2 cells, esiHP9 based on one of the amplified sequence that sharing 87% similarity to the target region suppressed HBsAg expression effectively and dose dependently. In vivo experiment showed that a single dose of 5 microg esiHP9 was able to reduce HBsAg and HBeAg level in the mouse sera by 88 and 77% despite of its 87% similarity to the target sequence, which was as good as esiHBVP that is 100% similar to the target sequence. All the data suggest that esiRNA can tolerate limited target sequence variations without losing its inhibitory capacity. It would be very helpful to suppress virus replication by RNAi despite of their high mutation rate.