Chemical synthesis and folding of APETx2, a potent and selective inhibitor of acid sensing ion channel 3

Acid sensing ion channels (ASICs) are pH-sensitive channels that are distributed in the central and peripheral nervous system and which are believed to play a key role in pain perception. APETx2, a 42-residue peptide toxin isolated from the sea anemone Anthopleura elegantissima, is the only known selective inhibitor of ASIC3 channels. Here we describe the total chemical synthesis of APETx2 by solid-phase peptide synthesis and native chemical ligation. The folded synthetic toxin had an IC₅₀ of 57 nM for inhibition of rat ASIC3 channels expressed in Xenopus oocytes, in agreement with the IC₅₀ reported for the native toxin (63 nM). The native chemical ligation approach should provide an efficient route for synthesis of other pharmacologically useful disulfide-rich toxins from venomous animals.     

实时荧光定量PCR法检测门冬氨酸鸟氨酸原料药中毕赤酵母菌DNA残留量

目的 建立可定量检测门冬氨酸鸟氨酸原料药中毕赤酵母菌DNA残留量的实时荧光定量PCR方法。方法 采用宿主细胞残留DNA样本前处理试剂盒（磁珠法）提取毕赤酵母菌DNA,利用毕赤酵母残留DNA检测试剂盒（PCR-荧光探针法）进行扩增反应,绘制标准曲线,建立毕赤酵母菌DNA残留量的Real-time PCR检测方法,并验证其准确性和精密性。结果 毕赤酵母菌DNA质量浓度在0.03~300 pg·μL^-1内线性良好（r>0.99）,定量限为0.03 pg·μL^-1;应用该法对3批门冬氨酸鸟氨酸原料药进行测定,毕赤酵母菌DNA残留量均远低于每剂10 ng。结论 该方法可用于门冬氨酸鸟氨酸原料药中毕赤酵母菌DNA残留量的定量测定。     

Effects of neuropeptide SF and related peptides on acid sensing ion channel 3 and sensory neuron excitability

Acid sensing ion channel 3 (ASIC3) is a cation channel gated by extracellular protons. It is highly expressed in sensory neurons, including small nociceptive neurons and has been proposed to participate in pain perception associated with tissue acidosis and in mechanoperception. Neuropeptide FF (NPFF) and FMRFamide have been shown to potentiate proton-gated currents from cultured sensory neurons and acid sensing ion channel (ASIC) cDNA transfected cells. In this study, we report that another mammalian peptide neuropeptide SF (NPSF), derived from the same precursor, also considerably increases the amplitude of the sustained current of heterologously expressed ASIC3 (12-fold vs. 19- and nine-fold for FMRFamide and NPFF, respectively) with an EC(50) of approximately 50 microM. Similar effects were also observed on endogenous ASIC3-like sustained current recorded from DRG neurons although of smaller amplitudes (two-, three- and seven-fold increase for NPSF, NPFF and FMRFamide, respectively), and essentially related to a slowing down of the inactivation rate. Importantly, this modulation induced changes in neuronal excitability in response to an electrical stimulus applied during extracellular acidification. ASIC3-mediated sustained depolarisation, and its regulation by neuropeptides, could thus be important in regulating polymodal neuron excitability particularly under inflammatory conditions where the expression levels of both NPFF precursor and ASIC3 are increased.     

VKORC1-3673G>A、CYP2C9*3、CYP4F2 rs2108622和CYP2C19*2基因多态性对中国汉族房颤患者华法林维持剂量的影响

目的 探讨VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622和CYP2C19^*2位点基因多态性对中国汉族房颤患者华法林维持剂量的影响。方法 收集107例服用华法林达维持剂量的汉族房颤患者的血样和临床相关资料,应用PCR-RFLP法检测VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622和CYP2C19^*2基因型,采用独立样本t检验分析基因型与华法林维持剂量的相关性。多元线性回归建立给药模型,探讨基因多态性对华法林维持剂量的影响。结果 VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622基因多态性和患者年龄、体质量能解释45.2%的华法林维持剂量差异。CYP2C19^*2基因多态性对本研究人群华法林维持剂量无影响。结论 VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622基因多态性显著影响中国汉族房颤患者的华法林维持剂量。     

丹参-红花药对配伍前后对大鼠肝药酶亚型CYP1A2、CYP2E1和CYP3A4活性的影响

目的 研究丹参、红花药对配伍前后对大鼠肝药酶亚型CYP1A2、CYP2E1和CYP3A4活性的影响。方法 分别选用咖啡因、氯唑沙宗和咪达唑仑作为CYP1A2、CYP2E1和CYP3A4的探针药物。将大鼠随机分为4组,即空白对照组、丹参（1.2 g生药/kg）组、红花（0.4 g生药/kg）组、丹参（1.2 g生药/kg）+红花（0.4 g生药/kg）组,按上述剂量ig给药7 d。于末次给药后30 min,尾iv探针药物咖啡因、氯唑沙宗和咪达唑仑溶液,在不同的时间点取血进行检测;以甲硝唑为内标,采用HPLC法检测探针药物咖啡因、氯唑沙宗和咪达唑仑的量,评价各药物组对大鼠CYP3A4、CYP2E1和CYP1A2活性的影响。结果 与空白对照组比较,丹参组咖啡因、氯唑沙宗和咪达唑仑的清除率（CL）有所增强,曲线下面积（AUC）减少,其半衰期（t_1/2）有减少趋势,但差异均不显著;红花组咖啡因和氯唑沙宗的CL有所降低,但差异不显著,咪达唑仑的CL显著降低（P<0.01）,氯唑沙宗的AUC增加,但差异不显著,咖啡因和咪达唑仑的AUC明显增加（P<0.05、0.01）;丹参+红花组咖啡因和氯唑沙宗的CL明显降低（P<0.05）,曲线下面积（AUC）明显增加（P<0.05）,其t_1/2有延长趋势,但差异不显著。结论 丹参、红花配伍后对CYP450亚型CYP1A2和CYP2E1有抑制作用,这可能是丹参、红花配伍协同增效的作用机制之一。     

Heterologous expression of Schistosoma japanicum signal protein 14-3-3 in Pichia pastoris and the subsequent immune response in mice

Schistosomiasis japonica, a zoonosis caused by Schistosoma japonicum, is endemic to the Philippines and China. Several vaccine candidates have been identified and tested in different animal models, but it is still unclear which will be optimal for testing in the field. Therefore, new antigens and strategies are necessary for vaccine development against schistosomiasis japonica. The Sj14-3-3 gene was amplified and subcloned into the expression vector pPICZα-B and transformed into P. pastoris X-33 by electroporation. Three transformants were induced with methanol. The cultural supernatant was collected and tested by SDS-PAGE and Western blotting. The protein of rSj14-3-3 was prepared and purified and BALB/c mice were immunized which was followed by a challenging infection. The immuno-protection was then evaluated. The Sj14-3-3 gene was expressed and secreted into the medium and its molecular weight was about 35000 as determined by SDS-PAGE. Western blotting showed that the protein had a high specificity against mouse-anti-Sj14-3-3 monoclonal antibody and rSj14-3-3 had a promising immune reactivity. The results of the immuno-protective experiments revealed that the worm reduction was 26.0%, 32.2%, and 36.8%, respectively. The number of eggs in liver tissue was reduced by 36.8%, 43.2%, and 46.1%, respectively. The recombinant Sj14-3-3 of eukaryotic expression in Pichia pastoris was successfully harvested. The molecular vaccine of Sj14-3-3 could partially induce resistance to the infection with S. japonicum in BALB/c mice. The recombinant protein Sj14-3-3 has promising immunological potentials for further approach to the diagnosis and development of molecular vaccine.     

UPLC-MS/MS法测定茯苓、茯苓皮和茯神中茯苓新酸B、去氢土莫酸、猪苓酸C、去氢茯苓酸和茯苓酸

目的 建立超高效液相色谱串联质谱（UPLC-MS/MS）法同时测定茯苓、茯苓皮和茯神中茯苓新酸B、去氢土莫酸、猪苓酸C、去氢茯苓酸和茯苓酸。方法 采用Shim-pack GIST C₁₈ AQ色谱柱（100 mm×2.1 mm,3 μm）,以乙腈–0.1%甲酸为流动相,梯度洗脱,体积流量0.4 mL/min,柱温40 ℃,进样量5 μL。质谱采用离子源：ESI,负离子模式采集,采集模式：多反应监测（MRM）,离子源温度150 ℃,毛细管电压2.5 kV,锥孔电压40 V,去溶剂气流量900 L/h,去溶剂气温度500 ℃。结果 茯苓新酸B、去氢土莫酸、猪苓酸C、去氢茯苓酸和茯苓酸在各自的线性范围内线性关系良好,平均回收率分别为97.80%、99.65%、97.32%、102.82%、99.57%,RSD值分别为3.46%、1.29%、3.01%、3.11%、1.89%。茯苓皮中5种三萜类成分含量均高于茯苓和茯神。结论 本法具有分析速度快、准确度高的优点,可为茯苓、茯苓皮和茯神的质量标准提高和开发利用提供依据。     

Studies on the specificity of CNF, a phospholipase A2 inhibitor isolated from the blood plasma of the South American rattlesnake (Crotalus durissus terrificus). I. Interaction with PLA2 from Lachesis muta muta snake venom

A phospholipase A₂ inhibitor has been previously purified and cloned from the blood plasma of the South American rattlesnake, Crotalus durissus terrificus. This inhibitor, named CNF for Crotalus neutralizing factor, interacts with crotoxin, the main neurotoxin from C. d. terrificus venom, abolishing its phospholipase A₂ activity. Crotoxin is a heterodimer of an acidic subunit (CA) and a basic phospholipase A₂ (CB). CNF acts by forming a stable non-toxic complex with CB, replacing CA in the toxic CA–CB of crotoxin.In the present investigation, we have shown that CNF has a broader specificity. It is able to inhibit the PLA₂ activity of the whole venom from the bushmaster snake (Lachesis muta muta), a species evolutionary related to Crotalus. Inhibition experiments have been carried out with four PLA₂ active components isolated from L. m. muta venom, one basic and three acidic ones. CNF inhibition is not restricted to the basic PLA₂, but extended to the three acidic forms as well.     

A novel kainate receptor ligand [H]-(2S,4R)-4-methylglutamate: Pharmacological characterization in rabbit brain membranes

Since kainate evokes large non-desensitizing currents at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, kainate is of limited use in discriminating between AMPA and kainate receptors. Following recent reports that (2S,4R)-4-methylglutamate is a kainate receptor-selective agonist, we have radiolabelled and subsequently characterized the binding of [³H]-(2S,4R)-4-methylglutamate to rabbit whole-brain membranes. [³H]-(2S,4R)-4-methylglutamate binding was rapid, reversible and labelled two sites (KD1 = 3.67 ± 0.50 nM/B_max1 = 0.54 ± 0.03 pmol/mg protein and K_D2 = 281.66 ± 12.33 nM/ B_max2 = 1.77 ± 0.09 pmol/mg protein). [³H]-(2S,4R)-4-methylglutamate binding was displaced by several non-NMDA receptor ligands: domoate > kainate -quisqualate -glutamate > 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX) (S)-AMPA = (S)-5-fluorowillardiine > NMDA. Neither the metabotropic glutamate receptor agonists (1S,3R)-ACPD or -AP4, together with the -glutamate uptake inhibitor -trans-2,4-PDC, influenced binding when tested at 100 μM. We conclude that [³H]-(2S,4R)-4-methylglutamate is a useful radioligand for labelling kainate receptors. It possesses high selectivity, and possesses a pharmacology similar to that for rat cloned low-affinity (Glu5 and 6) kainate receptor subunits.     

Expression of thymosin α1-thymopentin fusion peptide in <Emphasis Type="Italic">Pichia pastoris</Emphasis> and its characterization

Thymopentin plays an important role in improving imbalanced immune systems of patients, however, it has a limited half-life in plasma. To get more stable and active thymopentin analogs, a fusion thymosin α1-thymopentin (Tα1-TP5) gene was synthesized and cloned into vector pGAPZαA. Tα1-TP5 fusion peptide was expressed in pichia pastoris and purified by metal chelating chromatography and gel filtration chromatography. The circular dichroism spectra (CD) indicated that the secondary structure of Tα1-TP5 fusion peptide is dominated by a-helix and random coil. In vitro analysis showed that the plasma half-life of Tα1-TP5 fusion peptide is 140 ± 14 min, which is longer than that of TP5 (5.6±0.7 min) and Tα1 (127±11 min). The in vitro activity assay presented that Tα1-TP5 fusion peptide has greater activity in promoting proliferation of Kunming mouse splenocytes, and in vivo experiment it showed better activity in promoting the phagocytosis of macrophages and secretion of IL-2 than both Tα1 and TP5. Our findings suggest that Tα1-TP5 fusion peptide might be a potential therapeutic agent.     

The TRPC2 ion channel and pheromone sensing in the accessory olfactory system

The mammalian vomeronasal organ (VNO) has emerged as an excellent model to investigate the signaling mechanisms, mode of activation, biological function, and molecular evolution of transient receptor potential (TRP) channels in real neurons and real physiological systems. TRPC2, a member of the canonical TRPC subfamily, is highly localized to the dendritic tip of vomeronasal sensory neurons. Targeted deletion of the TRPC2 gene has established that TRPC2 plays a fundamental role in the detection of pheromonal signals by the VNO. TRPC2-deficient mice exhibit striking behavioral defects in the regulation of sexual and social behaviors. A novel Ca²⁺-permeable, diacylglycerol-activated cation channel found at the dendritic tip of vomeronasal neurons is severely defective in TRPC2 mutants, providing the first clear example of native diacylglycerol-gated cation channels in the mammalian nervous system. The TRPC2 gene has become an important marker for the evolution of VNO-dependent pheromone signaling in primates.     

大黄、枳实、厚朴不同炮制品对小承气汤中药效组分的影响

目的研究大黄、枳实、厚朴饮片变化对小承气汤药效组分的影响,以期为临床的合理应用和饮片的质量标准提供参考。方法采用HPLC法分别测定各类成分。大黄游离蒽醌类(芦荟大黄素、大黄酸、大黄素、大黄酚、大黄素甲醚):Syncronis C_(18)色谱柱(250 mm×4.6 mm,5μm);流动相:甲醇–0.1%磷酸;梯度洗脱;体积流量0.8 m L/min;柱温30℃;进样量10μL;检测波长254 nm。大黄结合蒽醌类(番泻苷B、番泻苷A):Syncronis C_(18)色谱柱(250 mm×4.6 mm,5μm);流动相:乙腈–0.05%磷酸;梯度洗脱;柱温30℃;进样量10μL;检测波长340 nm。枳实黄酮苷类(芸香柚皮苷、柚皮苷、橙皮苷、新橙皮苷):Syncronis C_(18)色谱柱(250 mm×4.6 mm,5μm);流动相:乙腈–水;梯度洗脱;体积流量0.7 m L/min;柱温40℃;进样量10μL;检测波长283 nm。厚朴木脂素类成分(和厚朴酚、厚朴酚):Syncronis C_(18)色谱柱(250 mm×4.6mm,5μm);流动相:乙腈–0.05%磷酸;梯度洗脱;体积流量0.7 m L/min;柱温30℃;进样量10μL;检测波长294 nm。结果小承气汤配伍剂量(大黄12 g–炒枳实9 g–姜厚朴6 g)不变,大黄、枳实、厚朴饮片改变时,小承气汤药效组分总量变化规律为:大黄–枳实–姜厚朴酒大黄–炒枳实–姜厚朴熟大黄–炒枳实–姜厚朴大黄炭–炒枳实–姜厚朴≈小承气汤大黄–炒枳实–厚朴,变化率分别为酒大黄组(6.561%)、熟大黄组(4.222%)、大黄炭组(0.118%)、枳实组(30.186%)、厚朴组(-11.218%)。除大黄炭组外,其余组的药效组分总量皆明显变化,其中枳实组变化最明显。结论同一味药材的不同炮制品在小承气汤处方中药效组分不同,对其他药味的影响亦不同,在小承气汤处方配伍中不可随意替代。     

Isolation of a snake venom phospholipase A2 (PLA2) inhibitor (AIPLAI) from leaves of Azadirachta indica (Neem): Mechanism of PLA2 inhibition by AIPLAI in vitro condition

A compound (AIPLAI (Azadirachta indica PLA(2) inhibitor)) purified from the methanolic leaf extract of A. indica (Neem) inhibits the cobra and Russell's viper venoms (RVVs) phospholipase A(2) enzymes in a dose-dependent manner. Inhibition of catalytic and tested pharmacological properties of cobra venom (Naja naja and Naja kaouthia) PLA(2) enzymes by AIPLAI is significantly higher (P<0.05) compared to the inhibition of PLA(2) enzymes of crude RVV (Daboia russelli) when tested under the same condition. Kinetic study reveals that in in vitro condition, AIPLAI inhibits the purified N. kaouthia PLA(2) enzymes in a non-competitive manner. The AIPLAI is quite stable at room temperature. The present study shows that AIPLAI holds good promise for the development of novel anti-snake venom drug in future.     

SDH2基因在白念珠菌环境适应性中的作用

目的 探究SDH2基因在白念珠菌环境适应性中的作用。方法 以野生型白念珠菌SC5314、SDH2基因敲除菌sdh2Δ/Δ、基因回复菌sdh2Δ/SDH2为实验对象;应用点板实验考察野生型菌、SDH2缺失菌和回复菌对外界压力刺激剂和抗真菌药物的敏感性;采用罗丹明6G外排实验考察SDH2基因缺失对白念珠菌药物外排能力的影响。结果 SDH2基因缺失后白念珠菌对细胞壁应激刺激剂咖啡因、氧化应激刺激剂二酰胺和甲萘醌表现出轻微耐受,值得注意的是SDH2基因敲除菌sdh2Δ/Δ对唑类抗真菌药物的敏感性明显增高,SDH2缺失导致白念珠菌药物外排能力下降。结论 SDH2缺失会导致白念珠菌对环境适应性的改变,包括对外界环境压力应答的改变和对唑类抗真菌药物敏感性的增加,以SDH2为靶基因,开发真菌特异性SDH2抑制剂,有望发现与唑类药物协同的新型抗真菌药物。     

大鼠酸感受离子通道亚基2a表达质粒的构建及生物学特性考察

目的构建大鼠酸感受离子通道亚基2a(acid-sensingion channel subunit 2a,ASIC2a)的表达质粒并研究其组成的同聚体离子通道的生物学特性。方法使用分子生物学技术构建大鼠ASIC2a亚基表达质粒;通过体外转录技术,使编码ASIC2a亚基的cRNA在爪蟾卵母细胞内表达并在膜表面形成同聚体离子通道;使用双电极电压钳技术研究ASIC2a的生物学特性。结果在注射ASIC2a亚基cRNA的爪蟾卵母细胞上,降低胞外液pH值可诱导出内向电流。H+诱发的ASIC2a内向电流具有稳态失活成分可被氨氯吡咪可逆性阻断,其pH50为5.12。提高胞外Ca2+浓度可降低H+诱发的电流幅度,其IC50为11.98 mmol.L-1。当细胞外液中无Na+时,H+基本上不能诱发出内向电流;当同时去除细胞外液中Na+和K+时,H+可诱发出外向电流。结论成功构建ASIC2a表达质粒;ASIC2a除了对Na+通透外,对K+也有一定的通透性,胞外Ca2+抑制ASIC2a孔道的开放。     

Upregulation of acid sensing ion channel 1a (ASIC1a) by hydrogen peroxide through the JNK pathway

Oxidative stress is intimately tied to neurodegenerative diseases, including Parkinson’s disease and amyotrophic lateral sclerosis, and acute injuries, such as ischemic stroke and traumatic brain injury. Acid sensing ion channel 1a (ASIC1a), a proton-gated ion channel, has been shown to be involved in the pathogenesis of these diseases. However, whether oxidative stress affects the expression of ASIC1a remains elusive. In the current study, we examined the effect of hydrogen peroxide (H₂O₂), a major reactive oxygen species (ROS), on ASIC1a protein expression and channel function in NS20Y cells and primary cultured mouse cortical neurons. We found that treatment of the cells with H₂O₂ (20 µM) for 6 h or longer increased ASIC1a protein expression and ASIC currents without causing significant cell injury. H₂O₂ incubation activated mitogen-activated protein kinases (MAPKs) pathways, including the extracellular signal-regulated kinase1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 pathways. We found that neither inhibition of the MEK/ERK pathway by U0126 nor inhibition of the p38 pathway by SB203580 affected H₂O₂-induced ASIC1a expression, whereas inhibition of the JNK pathway by SP600125 potently decreased ASIC1a expression and abolished the H₂O₂-mediated increase in ASIC1a expression and ASIC currents. Furthermore, we found that H₂O₂ pretreatment increased the sensitivity of ASIC currents to the ASIC1a inhibitor PcTx1, providing additional evidence that H₂O₂ increases the expression of functional ASIC1a channels. Together, our data demonstrate that H₂O₂ increases ASIC1a expression/activation through the JNK signaling pathway, which may provide insight into the pathogenesis of neurological disorders that involve both ROS and activation of ASIC1a.     

Heterologous expression of a gene that codes for Pg8, a scorpion toxin of Parabuthus granulatus, capable of generating protecting antibodies in mice

A novel peptide named Pg8 was purified from the venom of the South African scorpion Parabuthus granulatus and its primary structure was determined. It contains 63 amino acid residues tightly folded by 4 disulfide bridges. The gene coding for this peptide was cloned from a cDNA library. By recursive PCR strategy a hybrid gene was constructed having a factor X recognition site for proteolysis and a modified sequence for preferential codon usage of E. coli. A pQE30 molecular vector already contained a His-tag was used for expression. This construction was expressed in BL21 and Origami strains. The fusion protein from inclusion bodies was separated by HPLC (yield approximately 5 mg/L) and properly folded in vitro. Lethality tests showed that the recombinant peptide was toxic and was used to immunize mice. A volume of 0.25 ml of the anti-serum produced was capable of protecting up to 3 LD₅₀ doses of pure toxin Pg8 but also, and more importantly, the entire soluble venom.     

免疫检查点抑制剂治疗期间并发肺孢子菌感染：两例病例报道并文献复习

近年来,免疫检查点抑制剂（ICI）在临床中广泛应用,给肿瘤患者带来了比放疗、化疗更进一步的生存获益。然而,在免疫抑制剂增强细胞免疫抗肿瘤的同时,也有可能增强机体正常的免疫反应,导致机体免疫耐受紊乱,引起相应器官出现不适症状,称之为免疫相关不良反应。其中,免疫相关性肺炎往往较难诊断,严重者可致命。肺孢子菌肺炎（PCP）作为一种机会性真菌感染性疾病,常发生于免疫力低下人群。鉴于ICIs对免疫功能的促进作用,目前的主要观点认为,肿瘤免疫治疗并不会增加肺孢子菌感染的机会。本文报道了两例免疫治疗期间发生肺孢子菌感染的病例,以期进一步加深人们对免疫相关性肺炎及PCP的认识。