A phase II,single-centre trial of neoadjuvant toripalimab plus chemotherapy in locally advanced esophageal squamous cell carcinoma

BackgroundEsophageal squamous cell carcinoma (ESCC) remains a challenging malignancy with poor prognosis and limited therapeutic methods. However, recent clinical trials of immune checkpoint inhibitors (ICIs) have shown promising results in the treatment of lethal malignancies. The second-line treatment of late-stage ESCC was approved based on the results of KEYNOTE-180, KEYNOTE-181 and ATTRACTION-1, ATTRACTION-3. Combining ICIs with chemotherapy in neoadjuvant therapy may benefit patients with locally advanced, resectable ESCC.MethodsA two-arm phase II trial was launched in July 2019 in Henan Cancer Hospital. The primary outcome measure will be completed within 21 months. The pathological complete response (pCR) rate is the primary endpoint, and the secondary endpoints include overall survival (OS), disease-free survival (DFS), the toxicities of the neoadjuvant toripalimab plus chemotherapy, the relationship between combined positivity score (CPS) of specimen and the treatment response, the relationship between lymphocyte infiltration and the treatment response, the progression-free survival (PFS) rate, and adverse events (AEs). It was assumed that the pCR rate of this trial might be 25%. Therefore, the 30 enrolled patients could reject the hypothesis at 75% (α=0.1).DiscussionThe study will determine the safety and efficacy of neoadjuvant immunochemotherapy for ESCC and provide enough evidence for phase III clinical trials.Trial registrationClinical Trials.gov, {"type":"clinical-trial","attrs":{"text":"NCT03985670","term_id":"NCT03985670"}}NCT03985670, Registered: October 24, 2019, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0008Z9D&selectaction=Edit&uid=U0002MIY&ts=2&cx=-i71o4q. Registry name: “Teripalimab Plus Chemotherapy in Local Advanced Esophageal Cancer”.     

Grain-boundary topological phase transitions

The formation and migration of disconnections (line defects constrained to the grain boundary [GB] plane with both dislocation and step character) control many of the kinetic and dynamical properties of GBs and the polycrystalline materials of which they are central constituents. We demonstrate that GBs undergo a finite-temperature topological phase transition of the Kosterlitz–Thouless (KT) type. This phase transition corresponds to the screening of long-range interactions between (and unbinding of) disconnections. This phase transition leads to abrupt changes in the behavior of GB migration, GB sliding, and roughening. We analyze this KT transition through mean-field theory, renormalization group theory, and kinetic Monte Carlo simulations and examine how this transition affects microstructure-scale phenomena such as grain growth stagnation, abnormal grain growth, and superplasticity.

Physical properties of polycrystalline materials depend strongly on the properties of their constituent grain boundaries (GBs). Like most material properties, GB properties are functions of temperature and may change abruptly at temperatures corresponding to phase transitions. Such GB phase transitions may explain the existence of critical temperatures at which abrupt changes in the nature of several physical phenomena, including grain growth stagnation (1) and superplasticity (2), occur.There are several types of GB phase transitions discussed in the literature. These include thermodynamic phase transitions such as GB structural transitions or faceting/defaceting transitions (which are first order) (3–5), roughening transitions (divergence in the height–height correlation function) which may be continuous (6), and improper transitions where the GB transforms from solid-like to glass-like (7). In this paper, we discuss a class of fundamentally different GB phase transitions. We identify a GB topological phase transition of a type of the class originally discussed by Kosterlitiz and Thouless (8). Such topological transitions may be thought of as defect binding/unbinding transitions. The most important type of defects for GB dynamics is disconnections (9). Disconnections are line defects, constrained to lie within the GB and characterized by both Burgers vector b and step height h. The set of possible disconnection modes {b,h} is set by GB bicrystallography. Disconnections (like dislocations) are topological defects, as seen through a Burgers circuit analysis (9).Below the topological or Kosterlitz–Thouless (KT) transition temperature TKT, the interaction between disconnections is long range, decaying as the inverse of their separation. The formation and migration of disconnections are severely restricted and GB mobility tends to be small (with important exceptions). On the other hand, above TKT, the long-range elastic field of disconnections is effectively screened. Hence, the KT transition may be viewed as a screening (or sliding) transition, where the screening parameter (diaelastic constant) diverges at TKT. The KT transition leads to abrupt changes in the GB migration mobility, roughness, sliding coefficient, etc.While the KT transition leads to GB roughening, this transition fundamentally differs from the roughening transition widely discussed in the literature (6). While this classic roughening phase transition is topological, the steps have no long-range elastic interactions and are not topological defects (nonlocal imperfections corresponding to singularities in an order parameter characterizing a broken symmetry) (10). On the other hand, the dislocation nature of disconnections implies that disconnections are fundamentally topological defects. Hence, the KT transition discussed in this paper corresponds to the screening of long-range elastic interactions, while the classical roughening transition arises from topologically stable configurations of steps (without long-range interactions).We analyze the KT transition first through mean-field theory and then apply renormalization group analysis to accurately predict the main features of this transition by formal extension to the thermodynamic limit (i.e., infinite length scales). The results are confirmed through a series of kinetic Monte Carlo (kMC) simulations. Our analysis shows that the KT transition temperature depends on the driving force for GB motion. For example, in curvature-driven grain growth, we find that at a fixed temperature, large grains are more likely to be below TKT (low mobility) and small grains above it (high mobility). This is a possible explanation of why grain growth in pure materials often stagnates at large grain size and superplasticity is generally restricted to small grain sizes and high temperatures. We confirm these results by comparing our renormalization group prediction of the grain size at which grain growth stagnation occurs with simulation data from the literature (1).     

重组人红细胞生成素(rHuEPO)在心脏围术期的应用

目的:探讨在心脏围术期重组人红细胞生成素(rHuEPO)加速红细胞生成、进行红细胞总动员的疗效及其副作用。方法:体外循环心脏手术病人64例,随机分为实验组和对照组。实验组从术前7天到术后7天皮下注射rHuEPO,每次10000U,隔日1次,同时口服葡萄糖亚铁400mg,3次/日。对照组不用rHuEPO,其他治疗同实验组。结果:(1)实验组用药后1周网织红细胞明显上升,术后7天、14天继续上升渐达峰值,与对照组比较差异显著(P<0.05);血色素、血球压积于术后7天、14天渐上升达术前水平。与对照组比较差异显著(P<0.05);(2)两组ALT、BUN、Cr、PT、纤维蛋白元、华法令剂量、高血压、癫痫比较差别均无显著差异(P>0.05);(3)两组失血量比较无显著差异(P>0.05)。实验组与对照组用血量分别为450±180ml和760±330ml,有显著差异(P<0.05)。结论:rHuEPO能使心脏围术期红细胞动员加强,心脏术后延迟性贫血恢复加快,异体输血量减少,且无明显毒副作用,临床应用前景广阔。     

Chemical properties of lipids strongly affect the kinetics of the membrane-induced aggregation of α-synuclein

Intracellular α-synuclein deposits, known as Lewy bodies, have been linked to a range of neurodegenerative disorders, including Parkinson’s disease. α-Synuclein binds to synthetic and biological lipids, and this interaction has been shown to play a crucial role for both α-synuclein’s native function, including synaptic plasticity, and the initiation of its aggregation. Here, we describe the interplay between the lipid properties and the lipid binding and aggregation propensity of α-synuclein. In particular, we have observed that the binding of α-synuclein to model membranes is much stronger when the latter is in the fluid rather than the gel phase, and that this binding induces a segregation of the lipids into protein-poor and protein-rich populations. In addition, α-synuclein was found to aggregate at detectable rates only when interacting with membranes composed of the most soluble lipids investigated here. Overall, our results show that the chemical properties of lipids determine whether or not the lipids can trigger the aggregation of α-synuclein, thus affecting the balance between functional and aberrant behavior of the protein.The protein α-synuclein is mainly found in the presynaptic termini of neurons (1). The protein has been shown to populate a highly unstructured form in its unbound state both in vitro and in vivo and to adopt an α-helical conformation when bound to membranes (2). The balance between these two states has been found to play a role both in the proposed biological function of the protein, including the regulation of synaptic plasticity, and in the kinetics of its pathogenic aggregation; the latter is the hallmark of a range of diseases, known as synucleinopathies, of which the most common is Parkinson’s disease (3, 4). α-Synuclein has been shown to have its highest affinity for membranes containing either anionic lipids or so-called ”packing defects” (5–7), where the latter are defined as low-density regions in bilayers with high exposure of the lipid hydrophobic chains attributable to a mismatch between lipid shape and bilayer curvature (6, 7).Biological membranes are highly heterogeneous and differ from one cell or organelle to another in terms of the physical and chemical properties of the membranes, including curvature, charge, fluidity, and packing of the hydrophobic chains (8–10). The variety of membrane structures in cells can be directly related to differences in lipid (and protein) composition, where properties such as length and saturation of the hydrocarbon chain as well as the charge and size of the polar head group are crucial in determining the properties of the membrane (8, 9). In particular, most chemical and thermotropic properties of a lipid molecule are known to vary almost linearly with the length of its hydrophobic chain. As some examples, the standard change in free energy of transfer of a lipid molecule from water into a bilayer (i.e., its solubility in water), the melting temperature, and the enthalpy of melting have all been found to be proportional to the number of aliphatic carbons in the hydrophobic chain, which ranges from 8 to 18 (11). In addition, the adsorption and partitioning of small molecules and proteins to membranes can also affect the structural and thermotropic properties of the latter, and the magnitude and characteristics of these changes depend on the nature of the molecular interactions (e.g., electrostatic, hydrophobic) (12, 13).The interactions between amphipathic proteins and membranes have been extensively studied over the last three decades (7, 14–22). In general, the amino acid sequences of these peripheral proteins are characterized by patterns of hydrophobic and polar residues such that the proteins fold into amphipathic α-helices upon binding to hydrophobic patches exposed at the membrane interface (16, 17). In particular, molecular dynamics simulations and neutron reflectometry studies of deposited bilayers have shown that the amphipathic helix in α-synuclein is primarily located in the vicinity of the lipid phosphate groups and the glycerol backbone (16, 23–25).Although the binding of α-synuclein to membranes has been well characterized for different lipid systems (26–28), the observed modulation of the kinetics of the conversion of monomeric α-synuclein into amyloid fibrils by different membranes is less well understood (29–32). Most studies of this phenomenon have been performed under conditions of mechanical agitation (32) and/or in the presence of catalyzing polymer surfaces (31), where α-synuclein aggregates also in the absence of lipids and where the mechanism of aggregation has not yet been elucidated. Here, we take a different approach using an experimental procedure with protein-repellant surfaces and under quiescent conditions (33) that enables the systematic study of the manner in which a change in lipid properties can affect the ability of a model membrane to initiate α-synuclein aggregation. Indeed, we have previously shown that the presence of model membranes composed of 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS) triggers the aggregation of α-synuclein by specifically enhancing the rate of primary nucleation (33). In addition, this study showed how the protein:lipid (P:L) ratio modulates the kinetics of α-synuclein aggregation in the presence of DMPS; at low P:L ratios, effectively all of the protein molecules are adsorbed onto the surface of the membrane in a thermodynamically stable α-helical state and no aggregation is observed. At high P:L ratios, however, the protein molecules populate both the free monomeric state and the membrane-bound state, leading to rapid amyloid formation (33).In the present study, we have applied this experimental procedure to probe how changes in the chemical (charge and solubility) and physical (thermotropic) properties of lipids affect the binding of α-synuclein and the magnitude by which model membranes can trigger α-synuclein aggregation. The results reveal that the efficiency of the binding of α-synuclein to model membranes is correlated with their fluidity and, conversely, that the self-assembly of the lipids is affected by their association with the protein. In addition, although α-synuclein has a high affinity for all of the fluid anionic model membranes investigated here, this interaction is not sufficient for the efficient induction of aggregation. Rather, the rate of amyloid fibril formation is shown to be inversely correlated with the free energy of transfer of the lipid molecule from water into the bilayer. These results indicate that the chemical properties of the lipids are likely to play an important role in perturbing the balance between functional and deleterious interactions of α-synuclein with membranes.     

Regulatory mechanisms of tau protein fibrillation under the conditions of liquid–liquid phase separation

One of the hallmarks of Alzheimer’s disease and several other neurodegenerative disorders is the aggregation of tau protein into fibrillar structures. Building on recent reports that tau readily undergoes liquid–liquid phase separation (LLPS), here we explored the relationship between disease-related mutations, LLPS, and tau fibrillation. Our data demonstrate that, in contrast to previous suggestions, pathogenic mutations within the pseudorepeat region do not affect tau441’s propensity to form liquid droplets. LLPS does, however, greatly accelerate formation of fibrillar aggregates, and this effect is especially dramatic for tau441 variants with disease-related mutations. Most important, this study also reveals a previously unrecognized mechanism by which LLPS can regulate the rate of fibrillation in mixtures containing tau isoforms with different aggregation propensities. This regulation results from unique properties of proteins under LLPS conditions, where total concentration of all tau variants in the condensed phase is constant. Therefore, the presence of increasing proportions of the slowly aggregating tau isoform gradually lowers the concentration of the isoform with high aggregation propensity, reducing the rate of its fibrillation. This regulatory mechanism may be of direct relevance to phenotypic variability of tauopathies, as the ratios of fast and slowly aggregating tau isoforms in brain varies substantially in different diseases.

Tau is a major neuronal protein that plays a key role in Alzheimer’s disease (AD) and a number of other neurodegenerative disorders that are collectively classified as tauopathies. The latter include frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), progressive supranuclear palsy, Pick’s disease, corticobasal degeneration, and chronic traumatic encephalopathy (1–5). Under normal physiological conditions, tau is localized to axons where it is involved in the assembly of microtubules (1–6). In tauopathies, the protein self-associates into different forms of filaments that contain largely hyperphosphorylated tau and have properties of amyloid fibrils (1–5).Alternative splicing of the MAPT gene that encodes tau results in six major isoforms in the human central nervous system. These isoforms differ with respect to the number of N-terminal inserts as well as the number of 31 to 32 residue pseudorepeat sequences in the C-terminal part of the protein (1–5). Structurally, tau is largely an intrinsically disordered protein, with local secondary structures existing only within the pseudorepeat region (1, 7). A large number of mutations have been identified in the latter region that correlate with inherited cases of FTDP-17 (8, 9). These mutations not only diminish the ability of tau to promote microtubule assembly, but many also promote self-association of tau into amyloid fibrils (10–12). This strongly suggests that tau misfolding and aggregation is one of the key events in disease pathogenesis.A number of recent reports indicate that purified full-length tau (tau441) has a high propensity to undergo liquid–liquid phase separation (LLPS) in vitro in the presence of crowding agents that emulate the high concentration of macromolecules in the cell. This was observed both for the phosphorylated (13) and nonphosphorylated protein (14–16), and it was determined that tau LLPS is driven largely by attractive electrostatic intermolecular interactions between the negatively charged N-terminal and positively charged middle/C-terminal regions of the protein (15). Tau condensation into droplets (complex coacervation) was also observed in the presence of polyanions such as RNA or heparin (17, 18). These observations in vitro are partially supported by studies in cells (13, 19–24), especially within the context of tau interaction with microtubules (21). However, it remains unclear whether tau could undergo LLPS in cells on its own or, rather, its recruitment to membraneless organelles such as stress granules is largely driven by interactions with other proteins and/or RNA. These limitations notwithstanding, the observations that tau has a propensity for LLPS have potentially important implications for the pathogenic process in tauopathies, as studies with other proteins involved in neurodegenerative diseases (e.g., TDP-43, FUS) indicate that the environment of liquid droplets is conducive to the pathological aggregation of these proteins (25–32). In line with these findings, it was recently suggested that LLPS can initiate tau aggregation. However, the evidence for this was very limited and largely based on optical microscopy observations (13).In the present study, we explored the relationship between pathogenic mutations of tau, protein LLPS, and aggregation into amyloid fibrils. Our data show that, in contrast to previous suggestions (13), pathogenic mutations within the pseudorepeat region do not affect the propensity of tau to undergo LLPS. These mutations, however, do dramatically accelerate the liquid-to-solid phase transition within the droplets, leading to rapid formation of fibrillar aggregates. Most important, this study also reveals a previously unrecognized mechanism by which LLPS can regulate the rate of amyloid formation in mixtures containing tau isoforms with different aggregation propensities. These findings strongly suggest that LLPS may play a major regulatory role in the formation of pathological tau aggregates in neurodegenerative diseases.     

Long term follow-up of Asian patients with chronic myeloid leukemia (CML) receiving allogeneic hematopoietic stem cell transplantation (HSCT) from HLA-identical sibling—evaluation of risks and benefits

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only known curative therapy for patients with chronic myeloid leukemia (CML), but is associated with significant morbidity and mortality. The recent introduction of imatinib mesylate (STI-571) and reduced intensity transplant regimens has made the choice of primary treatment for patients with CML increasingly difficult. We have evaluated the outcome of 53 patients who have received allogeneic HSCT from human leukocyte antigen (HLA)-identical sibling donors between October 1985 and March 2002, determined the variables affecting the outcome, and tried to define indications for this aggressive approach. Successful engraftment occurred in 49 (98%) of evaluable patients. Acute graft-versus-host disease (GVHD) of grade II to IV severity was observed in 63% of the evaluable patients whereas the incidence of chronic GVHD was 57.5%. The Kaplan-Meier estimate of survival at 10 years was 54% [95% confidence interval (CI): 38–70%] and 31% (95% CI: 6–56%) for patients with first chronic phase and more advanced diseases, respectively. Multivariate analysis showed that younger age, absence of grade III-IV GVHD, the use of busulphan and cyclophosphamide (BuCy) as preparative regimen, and transplantation performed after January 1992 were factors associated with improved survival. Patients who were 30 years of age or younger who had transplantation done within 1 year after diagnosis during their first chronic phase of disease had a particularly good prognosis, with a probability of surviving 10 years of 72% (95% CI: 52–92%). We conclude that allogeneic HSCT remains a feasible option for Asian patients with CML. The most favorable outcome is observed in younger patients with early phase of the disease.     

Nitrogen Dissolution in Liquid Ga and Fe: Comprehensive Ab Initio Analysis,Relevance for Crystallization of GaN

The dissolution of molecular nitrogen in Ga and Fe was investigated by ab initio calculations and some complementary experiments. It was found that the N bonding inside these solvents is fundamentally different. For Ga, it is between Ga4s and Ga4p and N2p states whereas for Fe this is by N2p to Fe4s, Fe4p and Fe3d states. Accordingly, the energy of dissolution of N2 for arbitrarily chosen starting atomic configurations was 0.535 eV/mol and −0.299 eV/mol for Ga and Fe, respectively. For configurations optimized with molecular dynamics, the difference between the corresponding energy values, 1.107 eV/mol and 0.003 eV/mol, was similarly large. Full thermodynamic analysis of chemical potential was made employing entropy-derived terms in a Debye picture. The entropy-dependent terms were obtained via a normal conditions path to avoid singularity of ideal gas entropy at zero K. Nitrogen solubility as a function of temperature and N2 pressure was evaluated, being much higher for Fe than for Ga. For T=1800 K and p=104 bar, the N concentration in Ga was 3×10−3 at. fr. whereas for Fe, it was 9×10−2 at. fr. in very good agreement with experimental data. It indicates that liquid Fe could be a prospective solvent for GaN crystallization from metallic solutions.     

Colonic delivery of dexamethasone from a prodrug accelerates healing of colitis in rats without adrenal suppression

Dexamethasone-β-d-glucuronide, a colon-specific prodrug of dexamethasone, may be useful in the treatment of ulcerative colitis and Crohn's colitis. The aim of this study was to evaluate colonic delivery and efficacy of this prodrug in the rat. Distribution of dexamethasone in luminal contents and tissues of the gastrointestinal tract and in plasma was measured after oral administration of dexamethasone-β-d-glucuronide or free dexamethasone. Efficacy of the prodrug and free drug was tested in an acetic acid-induced rat colitis model. Healing of induced colitis was assessed by measuring net intestinal fluid absorption, colonic surface area of ulceration, histology, and myeloperoxidase activity. Glucocorticosteroid toxicity was evaluated with serum corticosterone and plasma adrenocorticotropic hormone levels. The drug delivery index (a measure of relative targeting efficiency) was 6.7 and 8.6 in the cecal and colonic mucosa, respectively. The prodrug was significantly more potent than free drug in improving net colonic fluid absorption while significantly reducing surface area of ulceration and histological grade in colitic rats. Treatment with free dexamethasone significantly reduced serum corticosterone levels to subnormal levels, and treatment with the prodrug maintained serum corticosterone and plasma adrenocorticotropic hormone levels near control levels. The prodrug dexamethasone-β-d-glucuronide delivers efficacious amounts of dexamethasone to the large intestine from lower doses than free dexamethasone.     

Presence,distribution, and pharmacological effects of neuropeptide Y in mammalian gastrointestinal tract

The quantitative distribution of neuropeptide Y (NPY) immunoreactivity has been determined along the length of the gastrointestinal tract in three mammalian species; rat, pig, and guinea pig. The peptide was shown to be present in all regions studied and in all three species. Exceptionally high concentrations were found in the region of the lower esophageal sphincter. Pretreatment of rats with 6-hydroxydopamine depleted NPY concentrations by 30–40%, indicating that NPY is colocalized in part with adrenergic nerves. Characterization of the NPY immunoreactivity by high-pressure liquid chromatography revealed a single major peak. NPY immunoreactivity derived from rat extracts eluted consistently earlier from the column than synthetic porcine standard, indicating minor species differences. Pharmacological studies using longitudinal muscle from guinea pig terminal ileum demonstrated that NPY caused a dose-dependent inhibition of the electrically stimulated, neurally mediated contraction of longitudinal smooth muscle. This suggested that NPY may act presynaptically to inhibit cholinergic transmission. The effects of various NPY fragments were also tested on the same preparation. The C-terminal fragments were active but were considerably less potent than NPY, while the free acid form of NPY and N-terminal fragment (1–19) were completely inactive. Thus, this study has demonstrated the presence of NPY in the gastrointestinal tract of various species, particularly within the lower esophageal sphincter. The pharmacological actions of the peptide suggest a role in the control of nonvascular smooth muscle tone.