Achyranthes bidentata polypeptides prevent apoptosis by inhibiting the glutamate current in cultured hippocampal neurons

Glutamate-induced excitotoxicity plays a critical role in the neurological impairment caused by middle cerebral artery occlusion.Achyranthes bidentata polypeptides have been shown to protect against neurological functional damage caused by middle cerebral artery occlusion,but the underlying neuroprotective mechanisms and the relationship to glutamate-induced excitotoxicity remain unclear.Therefore,in the current study,we investigated the protective effects of Achyranthes bidentata polypeptides against glutamate-induced excitotoxicity in cultured hippocampal neurons.Hippocampal neurons were treated with Mg^2+-free extracellular solution containing glutamate(300μM)for 3 hours as a model of glutamate-mediated excitotoxicity(glutamate group).In the normal group,hippocampal neurons were incubated in Mg^2+-free extracellular solution.In the Achyranthes bidentata polypeptide group,hippocampal neurons were incubated in Mg^2+-free extracellular solution containing glutamate(300μM)and Achyranthes bidentata polypeptide at different concentrations.At 24 hours after exposure to the agents,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Hoechst 33258 staining were used to assess neuronal viability and nuclear m'orphology,respectively.Caspase-3 expression and activity were evaluated using western blot assay and colorimetric enzymatic assay,respectively.At various time points after glutamate treatment,reactive oxygen species in cells were detected by H2 DCF-DA,and mitochondrial membrane potential was detected by rhodamine 123 staining.To examine the effect of Achyranthes bidentata polypeptides on glutamate receptors,electrophysiological recording was used to measure the glutamate-induced inward current in cultured hippocampal neurons.Achyranthes bidentata polypeptide decreased the percentage of apoptotic cells and reduced the changes in caspase-3 expression and activity induced by glutamate.In addition,Achyranthes bidentata polypeptide attenuated the amplitude of the glutamate-induced current.Furthermore,the glutamate-induced increase in intracellular reactive oxygen species and reduction in mitochondrial membrane potential were attenuated by Achyranthes bidentata polypeptide treatment.These findings collectively suggest that Achyranthes bidentata polypeptides exert a neuroprotective effect in cultured hippocampal neurons by suppressing the overactivation of glutamate receptors and inhibiting the caspase-3-dependent mitochondrial apoptotic pathway.All animal studies were approved by the Animal Care and Use Committee,Nantong University,China(approval No.20120216-001)on February 16,2012.

Facile Preparation of Polypeptides:Moisture Insensitive and Superfast Ring Opening Polymerization of N-Carboxyanhydrides

(a)NCA polymerization initiated by LiHMDS or other initiators in THF,initiator i)n-hexylamine,ii)HMDS,iii)bipyNi(COD);(b)LiHMDS-initiated open vessel polymerization of BLGNCA at 26 mg and 2 g scale;(c)GPC traces of poly-BLG at variable DP;(d)Reaction rates of LiHMDS and hexylamine initiated BLGNCA polymerization in THF with NCA:initiator ratio of 100∶1 and initial NCA concentration at 0.2 mol/L;(e)CD spectra of poly-BLG at variable DP prepared from LiHMDS-initiated NCA polymerization.

DEFENSE MECHANISMS OF URINARY BLADDER:STUDIES ON ANTIMICROBIAL POLYPEPTIDES FROM BLADDER MUCOSA

The acid soluble extract of the bladder mucosal surface was obtained by washing out the bladder with dilute acetic acid in the presence of protease inhibitors. The wash out materials from rats, rabbits, pigs, and humans manifested strong bactericidal activity against E.coli in vitro. The ultrafiltrate of the human material, which contained two major peptides with apparent molecular masses of 6 7 kD and 8 5 kD, respectively, showed potent bactericidal activity against E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus sanguis.Three antibacterial polypeptides (PiBPs) were purified from the porcine material. The molecular masses of PiBP 5, PiBP 11 and PiBP 25 were 5773.3 Da, 11127.8 Da and 25073 Da, respectively. PiBP 5 was unusually rich in glycine, serine and threonine residues(20 0, 16 3 and 10 4 mo1%, respectively), and N terminal amino acid sequencing revealed that PiBP 5 was homologous (83 3% identity in an 18 residue overlay) to the “tail” of human cytokeratin 7. Although the amino acid compositions of PiBP 11 and PiBP 25 were established, both had blocked N termini and primary sequence data were not obtained. These results provided evidence indicating that the presence of peptides in the bladder mucosa could enable it to kill adherent bacteria.

Force-Regulated Adhesion and Activation Study of Integrin Targeting Polypeptides

Integrins are heterodimeric cell surface receptors that bind to ligands on another cell,e.g.intercellular adhesion molecule 1(ICAM-1),or the extracellular matrix.Integrins play an important role in immune system,and they participate in inflammation,thrombosis,and proliferation,migration and apoptosis of tumor cells.They mediate adhesion and transduce signals across the membrane usually under the influence of forces.A recent study has shown that integrins bind and activate transforming growth factorβisoform(TGF-β)which is involved in tumor suppression and growth,and blocking the binding of TGF-βto integrin can inhibit tumor growth.RGD(arginine-glycine-aspartate)small peptide,which competitively inhibits ligand binding to integrins,has been approved as an injectable drug.However,when the RGD is used to block cancer-related extracellular signaling pathways,it will also cause activation of integrins for a period,and stimulate the transduction of intracellular signals constantly.Therefore,it is necessary to explore for new drugs that can selectively control conformational state of integrins without activating or blocking all of them.In this study,we selected two small peptides,KQAGDV and RTDLDSLRT,that combined with integrins and do not contain an RGD sequence.The non-RGD polypeptide RTDLDSLRT has been reported to have a binding site with integrins and the binding affinity is on nanomolar scale.For the motif of the fibrinogen y chain C-terminal KQAGDV,it can adhere to the head of the integrins.The micropipette aspiration technique and electron microscopy techniques were used to study the adhesion and activation of integrins by peptides,respectively.Micropipette aspiration technique was used to investigate the adhesion frequency of peptide and integrin on Jurkat cell.The pressure system was used to supply a controllable negative pression to the microtube,and two micropipettes were used to absorb red blood cells and Jurkat cells,respectively.The red blood cells were coated with small peptides and can serve as a force sensor after being sucked when two cells were connected.The binding kinetics of integrin and peptides interactions was determined by fitting the curves constructed using adhesion probability between two cells as a function of time.The curves were fitted using a small system probabilistic kinetic model to estimate a pair of kinetic parameters,including the zero force reverse rate kr0,and the cellular binding affinity Acmrm1Ka0.The adhesion frequency yielded P(t)=75%and 57%for RGD and KQAG DV peptides,respectively.We obtained Acmrm1Ka0=1.40 and kr0=0.32 s-1,for RGD,and Acmrm1Ka0=0.85 and kr0=0.54 s-1 for KQAGDV.The RGD peptide has a higher adhesion frequency and lower dissociation rate than the KQAGDV peptide.Electron microscopy techniques was used to observe the activation of integrins by peptides.Jurkat cell expressing integrins was bound to a magnetic bead and bottom plate which were coated with different integrin-binding peptides.Then,we manipulated the beads in a controlled direction by changing the magnetic field nearby,and the forces were applied to the cell.The target cells were fixed and then observed by scanning electron microscope or transmission electron microscope.Jurkat cells contain abundant flexible microvilli of which there are many parallel bundles of actin filaments inside.By electron microscopy analysis,the cell connected with magnetic bead coated with RGD were found to be protruded and the size of microvilli increased up to#-fold of the length of the KQAGDV sample.The microvilli exhibited a curved agglomerate structure under a force-free condition.Moreover,a higher proportion of cells were activated in the presence of RGD than KQAGDV.In conclusion,the binding affinity of KQAGDV to integrin is weaker than RGD,and KQAGDV can bind with integrins effectively with a lower activated proportion.Our results indicate the peptides may selectively bind to integrins without activating them.

Protective effects of Achyranthes bidentata polypeptides on retinal ganglion cells post-optic nerve crush in rats

Achyranthes bidentata polypeptides（ABPP） have been reported to inhibit apoptosis of retinal ganglion cells（RGCs）.The present study investigated the protective effects of ABPP on RGCs in a rat model of optic nerve injury.With prolonged injury time,RGC densities were gradually decreased.ABPP（5 μg） significantly increased RGC densities and upregulated growth associated protein 43 expression in rats with optic nerve injury.Results demonstrate that ABPP can protect RGCs and promote axonal growth after optic nerve crush.

Determined of antioxidant activity and preventing DNA damage effect of peanut polypeptides by chemiluminescence method

To estimate the antioxidant activities of Peanut polypeptides （PPs） by using a chemiluminescence （CL） method in vitro. The scavenging ability of PPs on superoxide anion, hydroxide radical, and hydrogen peroxide was determined by the Pyrogallol-Luminol system, the CuSO4-Phen-Vc-H2O2 system, and the luminol-H2O2 system, respectively. DNA damage preventing the effect of PPs was determined by the CuSO4-Phen-Vc-H2O2-DNA CL system. The results shows that PPs had good effect on the scavenging ability of superoxide anion （IC50=9.68±0.12 mg/ml）. PPs could scavenge hydroxide radical effectively （the IC50 value was 46.06±0.08 μg/ml）. PPs had a good scavenging ability on hydrogen peroxide, which had a relatively low IC50 value （0.17±0.07 mg/ml）. PPs （the IC50 value was0.72±0.11 mg/ml） were powerful on the DNA damage preventing effect. PPs possesses a good scavenging potency on ROS in different systems, but different results exist in different systems.

Cationic polypeptides in a concept of oppositely charged polypeptides as prevention of postsurgical intraabdominal adhesions

Background: Two differently charged polypeptides, α-poly-L-lysine and poly-L-glutamate, have previously been shown to effectively reduce postoperative intraabdominal adhesions. Though α-poly-L-lysine showed toxicity in doses too close to the lowest therapeutic dose, the aim in the present study was to investigate the possible antiadhesive effect of another four cationic polypeptides. Materials/Methods: 125 mice were studied with a standardized and reproducible adhesion model and given epsilon poly-L-lysine, lactoferrin, lysozyme and polyarginine respectively in a combination with poly-L-glutamate. Epsilon poly-L-lysine was also tested in different concentrations and as single treatment. Results: All four cationic polypeptides above showed a significantly better anti-adhesive effect than the controls receiving saline (p<0.05). Epsilon poly-L-lysine had the best antiadhesive effect of the new substances tested in the experiment. Single treatment with the epsilon poly-L-lysine showed toxic side effects. Discussion: We have shown that epsilon poly-L-lysine, polyarginine, lysozyme and lactoferrin, in descending order, all can reduce postoperative intraabdominal adhesions in mice when combined with poly-L-glutamate. There were side effects of epsilon poly-L-lysine resembling those of α-poly-L-lysine, although less toxic. The antiadhesive effect of epsilon poly-L-lysine did not reach the level of α-poly-L-lysine. Further studies will concentrate on additional investigation, trying to modify the α-poly-L-lysine to lower its toxicity. The less toxic epsilon poly-L-lysine also needs further attention in our research of antiadhesive bioactive polypeptides.

SURFACE MODIFICATION OF POLYPROPYLENE MICROPOROUS MEMBRANE BY TETHERING POLYPEPTIDES

Two kinds of polypeptides were tethered onto the surface of polypropylene microporous membrane （PPMM） through a ring opening polymerization of L-glutamate N-carboxyanhydride initiated by amino groups which were introduced by ammonia plasma and y-aminopropyl triethanoxysilane treatments. X-ray photoelectron spectroscopy （XPS）, attenuated total reflectance Fourier transform infrared spectroscopy （FT-IR/ATR）, scanning electron microscopy （SEM）, together with water contact angle measurements were used to characterize the modified membranes. XPS analyses and FT-IR/ATR spectra demonstrated that polypeptides are actually grafted onto the membrane surface. The wettability of the membrane surface increases at first and then decreases with the increase in grafting degrees of polypeptide. Platelet adhesion and murine macrophage attachment experiments reveal an enhanced hemocompatibility for the polypeptide modified PPMMs. All these results give evidence that polypeptide grafting can simultaneously improve the hemocompatibility as well as reserve the hydrophobicity for the membrane, which will provide a potential approach to improve the performance of polypropylene hollow fiber microporous membrane used in artificial oxygenator.

Synthesis and Cleavage Activity of Artifical Minic Polypeptides

Two artificial minic polypeptides which are synthetic analogues of natural products with DNA affinity were synthesized, and theirs cleavage activity with DNA were examined. The structures of these compounds was confirmed by ^1H NMR, MS and IR.

Construction of Expressing Plasmids of Recombinant FN Polypeptides with Bifunctional-domain and the Characterization of the Products Expressed in E. Coli

Two expressing plasmids have been constructed and used to express two bifunctional-domain recombinant polypeptides of human fibronectin (FN) in E. coli. One was CH50 (Pro1239-Ser1515 of FN linked with Ala1690-Thr1960 of FN through Met) and the other was CH56 (Pro1239-Thr1960 of FN). Both of two polypeptides were capable of binding heparin and were purified by heparin-a-garose affinity chromatography. The purified products were capable of binding cells. The production of CH50 and CH56 polypeptides provided a fundamental basis for further study of the anti-metastatic function of recombinant fibronectin polypeptides.

Structure Characterization of Silk Fibroin Crystalline Domain Polypeptides Expressed in Escherichia coli

The molecular conformations of four silk fibroin crystalline analogues [GAGAG-X] 16(G,Gly;A,Ala;X=Ala,Ser,Tyr or Val,designated eGA,eGS,eGY or eGV),carried out using molecular design and expressed by Escherichia coil(E.coli),were evaluated by Raman spectra analysis.The abilities of forming β-sheet structure were determined by thioflavin T(ThT) fluorescence spectra analysis.In terms of molecular conformation,except eGY that could not form significant typical molecular conformation,eGS and eGV were mainly composed of β-sheets while eGA tended to form β-turn.β-turn was also present in eGY and absent in eGS and eGV.In terms of β-sheet structure,eGS had the highest β-sheet content,followed by eGV,and eGA had the lowest content,furthermore,β-sheet structures were more stable in eGS and eGV than those in eGA and eGY.

Therapeutic effects of velvet antler polypeptides on hepatic fibrosis in rats

OBJECTIVE To explore the therapeutic effects and underlying mechanisms of velvet antler polypeptides(VVAPs)in CCl4-induced experimental hepatic fibrosis in rats.METHODS Anti-hepatic fibrosis properties of VAPs were tested by Subcutaneous injection(SC)into male Wistar rats of CCl4- induced experimental hepatic fibrosis.After SC injections for 45 consecutive days at doses of 5mg·kg-1(low dose,VAPsL),10mg·kg-1(mid-dose,VAPsM)and 20mg·kg-1(high-dose,VAPsH),the rats were sacrificed and the various indicators were evaluated and tested.Observed hepatic cells degeneration and necrosis,inflammatory infiltration and levels of serum enzymes to assess treatment of VAPs;The expression levels of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),MDA,and hydroxyproline(HYP)in liver tissue were analyzed;RT-PCR analysis was carried out to detect the expression levels of matrix metalloproteinases2(MMP-2)and tissue inhibitor of metalloproteinases 1(TIMP-1)in liver tissue.RESULTS VAPs has obvious anti-hepatic fibrosis effects.Hepatocyte swelling,fatty degeneration was significantly reduced,reducing infiltration of inflammatory cells.Release of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)decreased significantly,reduction of hyaluronic acid(HA)and laminin(LN)obviously,at the same time,the content of total protein and albumin increased significantly in serum.Activity of SOD and GSH-Px was significantly raised and the content of MDA and HYP was reduced significantly in liver tissue.Expression levels of MMP-2and TIMP-1 mRNA in liver were decreased significantly.These improvements were more significant in high-dos and mid-dose groups(P<0.05 or P<0.01 vs model group).CONCLUSION These findings suggest VAPs can significant treat the hepatic fibrosis,which may be due to protect liver cells and improve liver functions by hydroxyl radical scavenging activity and great effect of antioxidation,and decrease the gene expression of MMP-2,improving exist-environment of liver cells and decreasing the gene expression of TIMP-1,prompting degradation of extracellular matrix.

Alteration of Crystallin Polypeptides in Rat Lenses during the Development of Galactose-induced Cataract

Some striking differences in relative polypeptide abundanceof crystallins were observed in normal and galactose-induced cataractouslenses of rat by means of SDS-PAGE.In the cataractous lenses aprominent band appeared at about 25 kDa and the αA chain increasedmarkedly,whereas the relative amount of the 31 kDa band decreasedsubstantially.These alterations are similar to the changes observed duringthe incubation of young mouse lenses in glucose-free medium.Eye Science1993;9:143-145.

Reduced Macrophage Uptake of Nanoparticles through Surface Modification of Polypeptides with Valine Residues

The structural and surface properties of nanomedicines play an important role in determining their biological fate. Surface chemistry of nanomedicines is one of the key parameters, where researchers used various strategies such as PEGylation to avoid the undesired clearance of nanoparticles (NPs) for enhanced targeting effect. Nevertheless, the fine-tuning of surface chemistry through polymer functionalization remains largely unexplored. In this concise report, we find that the incorporation of only 10 mol% valine residues into the surface-anchored poly(L-glutamic acid) significantly lowered the macrophage uptake of NPs. The introduction of other hydrophobic amino acid residues, however, increased the NPs internalization instead. The chirality and the side-chain structure of valine played an important role in the unexpected uptake behavior. We believe this work highlights the impact of slight changes of the surface-anchored polymer structure on the behavior of NPs, drawing people's attention to the careful design of surface chemistry to optimize the nanomedicine design.

Bioactive fibrous scaffolds with programmable release of polypeptides regulate inflammation and extracellular matrix remodeling

Inflammation manipulation and extracellular matrix(ECM)remodeling for healthy tissue regeneration are critical requirements for tissue engineering scaffolds.To this end,the bioactive polycaprolactone(PCL)-based scaffolds are fabricated to release aprotinin and thymosinβ4(Tβ4)in a programmable manner.The core part of the fiber is composed of hyaluronic acid and Tβ4,and the shell is PCL,which is further coated with heparin/gelatin/aprotinin to enhance biocompatibility.The in vitro assay demonstrates that the controlled release of aprotinin prevents initial excessive inflammation.The subsequent release of Tβ4 after 3 days induces the transition of macrophages from M1 into M2 polarization.The manipulation of inflammatory response further controls the expression of transforming growth factor-βand fibroblast activation,which oversee the quantity and quality of ECM remodeling.In addition,the gradual degradation of the scaffold allows cells to proliferate within the platform.In vivo implant evaluation convinces that PCL-based scaffolds possess the high capability to control the inflammatory response and restore the ECM to normal conditions.Hence,our work paves a new way to develop tissue engineering scaffolds for inflammation manipulation and ECM remodeling with peptide-mediated reactions.

Biological properties of self-assembled nanofibers of elastin-like block polypeptides for tissue-engineered vascular grafts:platelet inhibition,endothelial cell activation and smooth muscle cell maintenance

Strategic materials design is essential for the development of small-diameter,tissue-engineered vascular grafts.Self-assembled nanofibers of elastin-like polypeptides represent promising vascular graft components as they replicate the organized elastin structure of native blood vessels.Further,the bioactivity of nanofibers can be modified by the addition of functional peptide motifs.In the present study,we describe the development of a novel nanofiber-forming elastin-like polypeptide(ELP)with an arginine-glutamic acid-aspartic acid-valine(REDV)sequence.The biological characteristics of the REDV-modified ELP nanofibers relevant to applications in vascular grafting were compared to ELP without ligands for integrin,ELP with arginine-glycine-aspartic acid(RGD)sequence,collagen and cell culture glass.Among them,REDV-modified ELP nanofibers met the preferred biological properties for vascular graft materials,i.e.(i)inhibition of platelet adhesion and activation,(ii)endothelial cell adhesion and proliferation and(iii)maintenance of smooth muscle cells in a contractile phenotype to prevent cell overgrowth.The results indicate that REDV-modified ELP nanofibers represent promising candidates for the further development of small-diameter vascular grafts.

Polypeptides inhibit HIV-1 replication by interfering viral Vpu-mediated tetherin degradation

Background:HIV-1 Vpu acts by counteracting the tethering function of tetherin and resulting in the release of HIV-1 virion.Disrupting Vpu-tetherin interactions may provide a promising new target for antiretroviral therapy.Methods:Polypeptides that covered the amino acid sequence on the interface of Vpu-tetherin complex were designed.Phenotypic susceptibilities and cellular toxicities to the polypeptides were measured.The mechanisms of the anti-HIV-1 polypeptides were determined by the Western blot analysis and laser confocal scanning.Seven 20-mer polypeptides from wild-type Vpu amino acid sequence were designed.Results:We report the design and identification of 3 novel anti-HIV-1 polypeptides that derived from Vpu se-quence which can efficiently inhibit HIV-1 infection.A pilot mechanism study showed that the active polypeptide could counteract Vpu-mediated tetherin downregulation.Laser confocal image scanning study showed that the polypeptides bound on the cell surface with a receptor specific binding manner,which may target tetherin that expressed on cell surface.Conclusion:Our work provided first evidence that counteracting Vpu-mediated tetherin downregulation could be a target for novel anti-HIV-1 drug design.Future works to provide direct evidence of inhibitors interact with teth-erin at atomic resolution and the development of small molecules inhibitors targeting Vpu-tetherin interactions may open a new avenue for novel antiretroviral therapy.

Targeted screening of an anti-inflammatory polypeptide from Rhopilema esculentum Kishinouye cnidoblasts and elucidation of its mechanism in alleviating ulcerative colitis based on an analysis of the gut microbiota and metabolites

Ulcerative colitis(UC)is a recurrent inflammatory bowel disease that imposes a severe burden on families and society.In recent years,exploiting the potential of marine bioactive peptides for the treatment of diseases has become a topic of intense research interest.This study revealed the mechanism underlying the protective effect of the dominant polypeptide PKKVV(Pro-Lys-Lys-Val-Val)of Rhopilema esculentum cnidoblasts against DSS-induced UC through a combined analysis of the metagenome and serum metabolome.Specifically,the polypeptide composition of R.esculentum cnidoblasts was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF/TOF-MS).Molecular docking showed that the dominant peptide PKKVV could bind better with tumor necrosis factor-α(TNF-α)than the original ligand.Subsequent animal experiments suggested that PKKVV could modulate disorganized gut microorganisms in mice with UC;affect serum metabolites through the arachidonic acid,glycerophospholipid and linoleic acid metabolism pathways;and further alleviate UC symptoms.This study provides a reference for the comprehensive development of marine bioactive substances and nonpharmaceutical treatments for UC.

Gadoxetic acid-enhanced magnetic resonance imaging in the assessment of hepatic sinusoidal obstruction syndrome in a mouse model

BACKGROUND Neoadjuvant chemotherapy can cause hepatic sinusoidal obstruction syndrome(SOS)in patients with colorectal cancer liver metastases and increases posto-perative morbidity and mortality.AIM To evaluate T1 mapping based on gadoxetic acid-enhanced magnetic resonance imaging(MRI)for diagnosis of hepatic SOS induced by monocrotaline.METHODS Twenty-four mice were divided into control(n=10)and experimental(n=14)groups.The experimental groups were injected with monocrotaline 2 or 6 days before MRI.MRI parameters were:T1 relaxation time before enhancement;T1 relaxation time 20 minutes after enhancement(T_(1post));a reduction in T1 relaxation time(△T_(1)%);and first enhancement slope percentage of the liver parenchyma(ESP).Albumin and bilirubin score was determined.Histological results served as a reference.Liver parenchyma samples from the control and experimental groups were analyzed by western blotting,and organic anion transporter polypeptide 1(OATP1)was measured.RESULTS T_(1post),△T_(1)%,and ESP of the liver parenchyma were significantly different between two groups(all P<0.001)and significantly correlated with the total histological score of hepatic SOS(r=-0.70,0.68 and 0.79;P<0.001).△T_(1)%and ESP were positively correlated with OATP1 levels(r=0.82,0.85;P<0.001),whereas T_(1post) had a negative correlation with OATP1 levels(r=-0.83;P<0.001).INTRODUCTION Hepatic sinusoidal obstruction syndrome(SOS)is also known as hepatic veno-occlusive disease of the liver[1].The main pathological feature of hepatic SOS is damage to liver terminal vessels,and the clinical symptoms of it include ascites and abdominal pain[2].It was first proposed in 1979 as an early complication of hematopoietic stem cell transplantation[3].The prevalence ranges from 5%to 60%,and hepatic SOS is a potentially severe complication and can even lead to death in severe cases[4].Recently,systemic neoadjuvant chemotherapy became widely regarded as one of the causes hepatic SOS in the patients with advanced metastatic colorectal cancer[5,6],especially those were treated with oxaliplatin[7,8].Oxaliplatin-based preoperative chemotherapy is used for patients with colorectal liver metastases as the standard regimen[8,9],because it could improve tumor resection outcome by shrinking the metastatic sites and reducing recurrence rate[10].Nevertheless,chemotherapy-induced hepatic SOS has been associated with a higher risk of postresection morbidity[11],such as intraoperative bleeding,intraoperative transfusions,and postoperative liver failure[12].Therefore,it is important to detect and diagnose of hepatic SOS timely.Currently,the gold standard is still based on liver biopsy[13],but it is an invasive procedure and has several limitations and complications,such as hemorrhage[14].A noninvasive diagnostic modality is needed for the assessment of hepatic SOS.Some noninvasive tools have been used for diagnosis of hepatic SOS.Researchers have utilized a preoperative platelet count and aspartate aminotransferase to platelet ratio index[15].In addition,some imaging methods such as shear wave ultrasonography,computed tomography,and gadoxetic acid-enhanced magnetic resonance imaging(MRI)have been promoted as useful methods for evaluation of hepatic SOS[16-18].Recent studies with monocrotaline(MCT)-treated rats were conducted to investigate diagnosis and prediction of severity of SOS.For example,intravoxel incoherent motion diffusion-weighted imaging,non-Gaussian diffusion models,and T1 rho quantification[19,20].The MCT-induced hepatic SOS animal model was reproducible,with a detailed pathological scoring criteria[21].Gadoxetic acid is a hepatocyte-specific contrast substance,which can provide parenchymal contrast in the hepato-biliary phase.It is reported that gadoxetic acid is absorbed into the liver parenchyma via organic anion transporter polypeptide 1(OATP1)on the hepatocyte membranes[22-24].Recently,several authors have described the feasibility of gadoxetic acid-enhanced MRI for the diagnosis of oxaliplatin-induced hepatic SOS[25].They mainly diagnosed hepatic SOS based on the signal intensity of the hepatobiliary specific phase.However,there were several limitations due to the inconsistency between signal intensity of the liver parenchyma and the concentration of contrast agent for evaluation of the degree of hepatic SOS[26].Therefore,we measured T1 relaxation time on parametric mapping because it is linearly related to the concentration of the contrast agent and is not affected by other factors[27].Yang et al[28]demonstrated T1 mapping on gadoxetic acid-enhanced MRI for the assessment of oxaliplatin-induced liver injury in a C57BL/6 mouse model.However,the main pathological changes in their model were hepatocyte degeneration and fibrosis.Therefore,we aimed to explore the effectiveness of T1 mapping based on gadoxetic acid-enhanced MRI for the diagnosis of hepatic SOS in a C57BL/6 mouse model,as well as a possible relation between OATP1 Levels and MRI parameters.

Regulation of the cellular uptake of nanopartides by the orientation of helical polypeptides

Controlling the cellular interactio n and internal izatio n of polymer-modified nan oparticles (NPs) is of central importa nee to the developme nt of promisi ng nano medici nes. Here, we describe the use of synthetic polypeptides for NP surface coati ng and regulati on of their cellular uptake behaviors by simply switching the conformation and anchoring orientation. Our results show that gold NPs (AuNPs) coated with a helical poly(Y-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)esteryl「glutamate)(L-P(EG3Glu)5o) from the C-terminus ((L-C)-AuNPs) exhibit greater zeta potential and more cellular uptake (2.0-5.5 fold higher) than those coated with the same polypeptide but anchored from the N-terminus ((L-N)-AuNPs), or from both the C- and N-terminus at a 1/1 molar ratio ((L-C/L-N)-AuNPs). A similar orientation-regulated cellular internalization pattern is observed in D-P(EG3Glu)50 but not the unstructured DL-P(EG3Glu)5o-rnodified AuNPs, suggesting an important and universal role of the helix-derived macrodipole in cellular uptake. Moreover, this orientation-governed internalization is successfully reproduced in P(EG3Glu)50-coated gold nano rods (AuNRs), and applied to the desig n of doxorubici reloaded polypeptide micelles. Simulation study offers time-resolved in sights regarding the NP-membrane in teracti ons and membrane remodeling. Thus, our study provides a delicate way of regulating the surface chemistry of NPs and the subsequent NP-cell interactions. Moreover, the results highlight the uniqueness of polypeptides in NP surface engineering, and urge a more careful consideration on the polymer orientation effect.