牛磺酸镁配合物对获得性长QT综合征亚型8模型下L型钙通道作用研究

目的 观察不同浓度牛磺酸镁配合物（TMCC）对获得性长QT综合征亚型8的抗心律失常机制。方法 采用Langendorff逆行主动脉灌流酶解法,急性分离获得豚鼠单个心室肌细胞;建立表达CACNA1C基因的HEK293细胞模型。BayK 8644（10 nmol/L）用来建立LQT8模型,采用全细胞膜片钳技术记录TMCC （0.01、0.10、1.00 mol/L）对对照和LQT8模型下HEK293细胞L型钙通道（LTCC）电流、豚鼠心室肌细胞动作电位的影响。结果 在HEK293细胞细胞中,与对照组比较,0.1、1 mol/L TMCC组I_Ca,L电流密度显著减弱,差异有统计学意义（P<0.05、0.01）。与对照组比较,BayK 8644组I_Ca,L的电流-电压（I-V）曲线显著下移,电流密度显著增强（P<0.01）,使半数激活电压明显升高3.23倍,激活曲线左移,激活加快。TMCC （0.01、0.1、1 mol/L）可明显减弱BayK 8644对I_Ca,L电流的增强作用,使下移的I-V曲线上移,0.1、1 mol/L浓度组差异有统计学意义（P<0.05、0.01）;TMCC各浓度组均明显降低半数激活电压（P<0.05、0.01）,恢复左移的激活曲线,使激活减慢。在豚鼠心室肌细胞中,与对照组比较,BayK 8644显著延长30%、50%和90%复极化动作电位持续时间（APD₃₀、APD₅₀和APD₉₀）（P<0.01）;0.01、0.1、1 mmol/L TMCC均可以减弱BayK 8644对APD₃₀、APD₅₀和APD₉₀的延长作用,0.1、1 mmol/L浓度组差异显著（P<0.05、0.01）。结论 TMCC通过缩短动作电位时程,减弱被增强的I_Ca,L电流,发挥一定的抗LQT8的作用。     

3,6-[二甲氨基]-二苯骈碘因甲酸盐对豚鼠单—心室肌细胞动作电位和慢内向钙电流的影响

采用全细胞电压钳技术,观察了3,6-[二甲氨基]-二苯骈碘因甲酸盐(IHC-64)对豚鼠单一心室肌细胞动作电位和慢内向钙电流(I_si)的影响。结果表明,IHC-64 20和200 μmol/L可明显缩短APD₂₀和APD₉₀。予先给予钙通道阻滞剂尼索地平可取消IHC-64缩短APD₂₀的作用。在电压钳条件下,上述浓度的IHC-64对I_si有明显的抑制作用,I_si由给药前的1.92±0.41 nA分别降低至给药后1.73±0.50 nA(P<0.05)和0.62±0.38 nA(P<0.01).提示IHC-64可能对心肌细胞钙通道有阻滞作用。     

苄基四氢巴马汀对豚鼠心室肌细胞钾电流及钙、钠电流的作用

目的：研究苄基四氢巴马汀（BTHP）对心肌细胞的作用特点,以探讨其抗心律失常机制。方法：用全细胞膜片钳技术考察BTHP对心室肌细胞钾电流及钙、钠电流的作用。结果：BTHP 30 μmol.L^-1明显阻滞延迟整流钾电流（I_K包括：I_Kr及I_Ks）。可使I_Kr及I_Kr,tail的幅值下降,且对I_Kr阻滞作用呈频率依赖性;对I_Ks及I_Ks,tail幅值也有明显的抑制作用。BTHP 200　μmol.L^-1可明显阻滞I_Ca,L,使其电流幅值降低,但对I_K1,I_Ca,T,I_Na电流均无影响。结论：BTHP可明显阻滞心室肌细胞I_Kr,I_Ks,I_Ca,L电流,且对I_Kr阻滞作用呈频率依赖性。     

苄基四氢巴马汀细胞内用药对豚鼠乳头状肌动作电位和心室肌细胞延迟整流钾电流的作用

目的　研究将苄基四氢巴马汀(BTHP)导入细胞内对豚鼠乳头状肌动作电位及单个心室肌细胞延迟整流钾电流的影响。方法　利用外加电压脉冲将药物导入乳头状肌细胞内，并用标准微电极方法测定动作电位；利用浓度差扩散方式使药物进入单个心室肌细胞内，采用全细胞膜片钳技术记录延迟整流钾电流（I_K）。结果　100 μmol.L^-1 BTHP使APD₂₀和APD₉₀分别延长13.5%和20.5%。30 μmol.L^-1 BTHP使I_K和I_K,tail分别从（14.1±2.2) pA.pF^-1和(4.0±0.6) pA.pF^-1降至(9.4±1.3) pA.pF^-1和(2.1±1.0) pA.pF^-1，下降率分别为33.2%和35.3%。 该药使I_K和I_K,tail的I-V曲线幅度降低，对曲线形状影响不明显。结论　BTHP入细胞内后可阻滞延迟整流钾电流和延长动作电位时程。     

苄普地尔对豚鼠甲亢性肥厚心肌中延迟整流钾电流的抑制作用

目的　研究苄普地尔(bepridil)对肥厚心肌细胞延迟整流钾电流(I_K)中快激活成份(I_Kr)和慢激活成份(I_Ks)及内向整流钾电流(I_K1)的作用。方法　全细胞膜片钳技术。结果　在肥厚心肌细胞中,Bepridil 30 μmol·L- 1 对I_Kr及I_Ks有阻断作用,抑制率分别为20.9% (0 mV)和27.2 % (+50 mV)。“Envelopeoftail”显示bepridil对I_Ks的阻断作用大于I_Kr。Bepridil(1 - 100 μmol·L^-1 )浓度依赖性的阻断I_Ks及I_Kr,其IC₅₀ 分别为23.8μmol·L^-1 和46.7μmol·L^-1 。Bepridil 30 μmol·L^-1 也能阻断I_K1 ,抑制率为15.1% (- 100 mV) ,但不影响其反转电位。结论　Bepridil对甲亢性豚鼠肥厚心肌中I_Ks,I_Kr及I_K1有阻断作用     

三七中人参三醇甙对羊心浦氏纤维动作电位及延迟整流钾电流的影响

三七中人参三醇甙(PTS)2.5μg/ml及5.0μg/ml均能明显延长羊心浦氏纤维动作电位时程(APD)包括APD₃₀,APD₅₀,APD₉₀,对动作电位幅度(APA)无明显影响。双微电极法电压钳实验证明,PTS能明显抑制羊心浦氏纤维延迟整流钾电流(I_x)的峰值,且此种抑制作用呈时间及剂量依赖性。揭示PTS通过阻滞延迟整流钾通道而延长APD。     

苦参碱、小檗胺与胺碘酮、RP58866抗心律失常作用的比较

目的阐明苦参碱和小檗胺抗心律失常作用弱于胺碘酮和RP58866的分子机制。方法采用冠脉结扎、电刺激和乌头碱诱导的心律失常模型观察药物的抗心律失常作用，采用全细胞膜片钳技术测定单个心室肌细胞的I_K1，I_Kr，I_Ks和 I_to。结果苦参碱和小檗胺对冠脉结扎、乌头碱诱发的大鼠心律失常有明显对抗作用，对家兔电刺激致颤阈（VFT）有明显提高作用，但与胺碘酮和RP58866相比，抗心律失常作用明显低于前者。电生理结果显示：苦参碱和小檗胺对家兔I_K1,I_Kr,I_Ks和犬I_to有抑制作用，但较胺碘酮和RP58866作用弱。结论苦参碱和小檗胺的抗心律失常作用及对I_K1,I_Kr,I_Ks和I_to的抑制作用弱于胺碘酮和RP58866。     

阿米洛利对豚鼠心肌细胞钾电流及钙电流的作用

目的研究阿米洛利（amiloride）对豚鼠心肌细胞钾电流及钙电流的作用。方法采用全细胞膜片钳技术记录豚鼠心室肌细胞钾通道及钙通道电流。结果阿米洛利在10~100 μmol·L^-1抑制L型及T型钙电流,不改变钙电流I-V曲线的形状，仅抑制这两型电流的幅度。当累积浓度达100 μmol·L^-1时，阿米洛利轻微抑制快激活延迟整流钾电流(I_Kr)，对慢激活延迟整流钾电流(I_Ks)无影响。阿米洛利在1~100 μmol·L^-1浓度依赖性地抑制内向整流钾电流(I_K1)。结论阿米洛利抑制电压依赖性的钾、钙电流，为其抗心律失常作用提供了离子基础。     

基于膜片钳技术的丹红注射液对人诱导多能干细胞衍生心肌细胞电生理的影响研究

目的 通过全细胞膜片钳实验,从心肌电生理层面探索丹红注射液(DHI)治疗乌头碱诱导心律失常的可能机制。方法 基于人诱导多能干细胞衍生心肌细胞(hiPSC-CMs)膜片钳技术,即时给药并观察乌头碱不同浓度(3、9、27 μmol·L^-1)对钠通道、hERG钾通道的抑制效果,进行造模条件的筛选;设置对照组、模型组(乌头碱1 μmol·L^-1长时间造模)、DHI (3、9、27 μL·mL^-1)组,乌头碱与DHI同时加药,记录动作电位幅度(APA)、放电频率、动作电位幅度下降50 %时的时程(APD₅₀)和动作电位幅度下降90 %时的时程(APD₉₀),并以对照组为标准,计算相对值;设置对照组、模型组、DHI (3 μL·mL^-1)组,乌头碱与DHI同时加药,观察3~5 min,记录钠离子、hERG钾离子、钙离子电流密度。结果 给予即时药物处理,3、9、27 μmol·L^-1的乌头碱对钠电流的抑制率分别为17.94 %、31.07 %、60.67 %,对hERG通道的抑制率分别为5.02 %、10.59 %、28.59 %;在短期内给乌头碱对hERG通道的抑制效果较为有限,而实际实验中,长时间的高浓度乌头碱孵育使钠电流被完全抑制,导致离子通道功能受损,因此选择乌头碱1 μmol·L^-1长时间给药制备模型。与对照组比较,模型组hiPSC-CMs相对APA、相对APD₅₀和相对APD₉₀显著下降(P<0.01、0.001),相对放电频率显著升高(P<0.001);钠电流在一定时间内减小,抑制率为30.18 %;hERG钾电流明显减小,抑制率为72.33 %;钙电流明显增大,电流增大191.35 %。与模型组比较,DHI 3、9、27 μL·mL^-1组相对放电频率显著降低(P<0.05、0.001)、相对APD₉₀显著升高(P<0.05、0.01),3 μL·mL^-1组相对APD₅₀显著升高(P<0.001);DHI组钠电流、hERG钾电流的减小及钙电流的增大均有一定缓解。结论 DHI可能可以通过影响钠、钾、钙通道来缓解乌头碱导致的心律失常现象。     

荭草苷对大鼠心室肌细胞钠通道的影响

目的 研究荭草苷（orientin,Ori）对大鼠心室肌细胞钠通道电流（I_Na）的影响,探讨Ori在离子通道层面的抗心律失常机制。方法 使用Langendorff恒温恒压灌流装置、单酶解消化法分离大鼠心室肌细胞,应用全细胞膜片钳技术记录、观察不同浓度Ori作用前后大鼠心室肌细胞钠通道电流（I_Na）的变化。结果 低于2 μmol·L^-1的Ori对I_Na无明显影响,3,10,30 μmol·L^-1的Ori使I_Na的I-V曲线显著上移,峰值钠电流（I_Na-Peak）由给药前的（-81.49±3.9）pA/pF依次变为（-74.38±4.1）pA/pF,（-63.05±2.8）pA/pF和（-55.35±3.2）pA/pF;Ori使激活曲线右移、失活曲线左移,失活后恢复曲线显著右移,最大半数激活电位（V_1/2-ac）由给药前的（-53.66±4.12）mV分别变为（-44.64±1.9）mV,（-38.95±1.7）mV和（-30.21±1.5）mV;最大半数失活电位（V_1/2-in）由给药前的（-51.68±0.76）mV分别变为（-60.17±1.5）mV,（-68.51±1.4）mV和（-75.22±1.37）mV,恢复时间（τ）由给药前的（18.38±0.84）ms分别变为（24.53±1.4）ms,（35.25±1.3）ms和（68.75±1.58）ms。结论 Ori能浓度依赖性抑制大鼠心室肌细胞的I_Na,并能显著影响其激活、失活及失活后恢复的动力学特征。     

A longitudinal assessment of aflatoxin M1 excretion in breast milk of selected Egyptian mothers.

Aflatoxins are potent toxins and carcinogens which can be excreted in the milk of exposed lactating mothers mainly in the form of aflatoxin M(1) (AFM(1)). We previously evaluated the level and frequency of AFM(1) in breast milk in a group of Egyptian mothers attending the New El-Qalyub Hospital, Qalyubiyah governorate, Egypt. In this study, fifty of those women who were AFM(1) positive were revisited monthly for 12 months to assess the temporal variation in breast milk AFM(1). AFM(1) was detected in 248 of 443 (56%) samples. In a multilevel model of the data there was a highly significant (p<0.001) effect of month of sampling on the frequency of AFM(1) detection with summer months having the highest frequency (>80%) and winter months the lowest frequency (<20%) of detection. AFM(1) was observed most frequently in June [OR 63, 95% CI (7.6, 522)]. The level of AFM(1) detection also followed this seasonal pattern with highest mean level in July (64 pg/ml milk, range 6.3-497 pg/ml milk) and the lowest mean level in January (8 pg/ml milk, range 4.2-108 pg/ml milk). The duration of lactation [p=0.0035, OR=1.08, 95% CI (1.02, 1.13)], and peanut consumption [p=0.06, OR=1.69, 95% CI (0.9, 2.9)] also contributed to the model. The identification and understanding of factors determining the presence of toxicants in human milk is important and may provide a knowledge driven basis for controlling the transfer of chemicals to infants.     

Prediction of volume of distribution in preclinical species and humans: application of simplified physiologically based algorithms

1. The present study was aimed at developing simplified physiologically based semi-mechanistic algorithms to predict V_ss and interspecies scaling factors to predict tissue-K_ps which require minimum input parameters, diminish the computing complexity and have better predictability.

2. V_ss of 86 structurally diverse compounds in preclinical species and 27 compounds in humans were predicted using only lung- and muscle-K_p as inputs. Interspecies scaling factor (s) were developed based on fold-differences in individual tissue lipid contents, relative organ blood flow: relative organ weight ratio between two species. Tissue-K_ps were predicted for 34 compounds using the newly developed interspecies scaling factors.

3. The predicted-to-experimental V_ss values for all the 113 compounds was 1.3?±?0.9 with 83% values being within a factor of two. The tissue-K_ps in rat, dog and human were predicted using experimental tissue-K_p data in rodents and interspecies scaling factors and here also, 83% of tissue-K_ps were within two-fold of the experimental values.

4. In conclusion, simplified physiologically based algorithms have been developed to predict both volume of distribution and tissue-K_ps, in which required input parameters as well as computing complexity have been noticeably reduced.

     

Serotonergic approaches in the development of novel antipsychotics

Schizophrenia is a chronic, debilitating neuropsychological disease characterised by positive, negative, and cognitive deficits. In recent years, new pharmacological treatment strategies have been developed to treat the sequalae of schizophrenia based upon more selective receptor activity profiles in the hope that treatment efficacy can be increased without inducing the side-effect profiles seen with current available therapies. One such strategy involves the development of combined (partial) 5-HT_1A agonists and D₂ receptor (partial) antagonists such as bifeprunox, SLV313, F15063 and SSR-181507 in an attempt to increase therapeutic efficacy of all symptom domains whilst alleviating adverse side effects. Other novel drugs including SLV310 and SLV314 combine selective serotonin reuptake inhibition (SSRI) functionality with D₂ receptor antagonism in an attempt to not only improve schizophrenic symptoms, but to also relieve other affective disorders intricately linked with the disorder. The main scope of this review will evaluate the major preclinical and clinical pharmacological findings concerning the aforementioned strategies and pharmacological agents, and compare their therapeutic potential with currently available antipsychotics; however, recent developments at other emerging serotonergic targets such as 5-HT_2C, 5-HT₆ and 5-HT₇ receptors will also be considered.     

In praise of H2O2, the versatile ROS,and its vanadium complexes

Hydrogen peroxide (H₂O₂) is generated in mitochondria in aerobic cells as a minor product of electron transport, is inhibited selectively by phenolic acids (in animals) or salicylhydroxamate (in plants) and is regulated by hormones and environmental conditions. Failure to detect this activity is due to presence of H₂O₂-consuming reactions or inhibitors present in the reaction mixture. H₂O₂ has a role in metabolic regulation and signal transduction reactions. A number of enzymes and cellular activities are modified, mostly by oxidizing the protein-thiol groups, on adding H₂O₂ in mM concentrations. On complexing with vanadate, also occurring in traces, H₂O₂ forms diperoxovanadate (DPV), stable at physiological pH and resistant to degradation by catalase. DPV was found to substitute for H₂O₂ at concentrations orders of magnitude lower, and in presence of catalase, as a substrate for user reaction, horseradish peroxidase (HRP), and in inactivating glyceraldehyde-3-phosphate dehydrogenase. superoxide dismutase (SOD) -sensitive oxidation of NADH was found to operate as peroxovanadate cycle using traces of DPV and decameric vanadate (V₁₀) and reduces O₂ to peroxide (DPV in presence of free vanadate). This offers a model for respiratory burst. Diperoxovanadate reproduces several actions of H₂O₂ at low concentrations: enhances protein tyrosine phosphorylation, activates phospholipase D, produces smooth muscle contraction, and accelerates stress induced premature senescence (SIPS) and rounding in fibroblasts. Peroxovanadates can be useful tools in the studies on H₂O₂ in cellular activities and regulation.     

Mechanisms of butylated hydroxytoluene chemoprevention of aflatoxicosis--inhibition of aflatoxin B1 metabolism

Chemoprevention of toxicoses and/or cancer through the use of nutrients or pharmacologic compounds is the subject of intense study. Among the many compounds examined, food additives such as antioxidants are being considered due to their ability to reduce disease formation by either induction or inhibition of key enzyme systems. One such compound, butylated hydroxytoluene (BHT), has been found to protect against cancer formation caused by exposure to aflatoxin B₁ (AFB₁) in rodents. We have shown that dietary BHT protects against clinical signs of aflatoxicosis in turkeys, a species that is very susceptible to this mycotoxin. In this study, the effect of BHT on AFB₁ metabolism and other cytochrome P450 (CYP)-related enzyme activities in turkey liver microsomes was examined to discern possible mechanisms of BHT-mediated protection against aflatoxicosis. Ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), prototype activities for CYP1A1 and 1A2, respectively, were decreased in the BHT fed (4000 ppm) animals, while oxidation of nifedipine, a prototype activity for CYP3A4, was increased. However, BHT added to microsomal incubations inhibited these CYP activities in a concentration-related manner. Importantly, BHT inhibited conversion of AFB₁ to the reactive intermediate AFB₁-8,-9-epoxide (AFBO), exhibiting Michaelis-Menton competitive inhibition kinetics (Ki = 0.81 μM). Likewise, microsomes prepared from turkeys fed BHT were significantly less active in AFBO formation compared to those from control birds. When turkeys were fed BHT for up to 40 days, residual BHT was present in liver, breast meat, thigh meat and abdominal fat in concentrations substantially below U.S. FDA guidelines for this antioxidant, but in concentrations greater than the Ki, likely sufficient to inhibit bioactivation of AFB₁in vivo. BHT-induced hydropic degeneration in the livers of BHT fed animals was significantly greater in birds that remained on BHT treatment for up to 30 days, but this lesion diminished in animals fed for 40 days or when returned to a control diet. The data indicate that the observed chemopreventive properties of BHT in turkeys may be due, at least in part, to its ability to inhibit hepatic AFB₁ epoxidation and also that the BHT-induced hydropic degeneration is reversible and does not appear to cause long-term effects.     

Determination of the kinetic properties of platycodin D for the inhibition of pancreatic lipase using a 1,2-diglyceride-based colorimetric assay

A 1, 2-diglyceride-based multi-step colorimetric assay to measure the pancreatic lipase activity was applied for the determination of the kinetic profiles of the lipase inhibition with a slight modification and the validity verification. With this assay method, our study revealed that platycodin D, one of major constituents of Platycodi Radix, inhibits the pancreatic lipase activity in a competitive type, with the value ofK _l being 0.18±0.02 mM. In addition, PD has affected the values ofK _{m, app} andK _cat/K _m in a dose- dependent manner. The results shed a meaningful light on how PD mediates lipid metabolism in the intestinal tracts. On the other hand, since the revised assay is sensitive, rapid, and does not affect the accuracy to the kinetic properties, it is applicable not only to evaluation of the kinetic properties of the pancreatic lipase, but also to highthroughput screening of pancreatic lipase activity.     

Urinary biomarkers of aflatoxin exposure in young children from Egypt and Guinea.

Aflatoxins are a major risk factor for hepatocellular carcinoma (HCC), and thus understanding the pattern of aflatoxin exposure in different regions is important in order to develop targeted intervention strategies. Given the early onset of HCC in many countries early life exposures may be important. This study investigated aflatoxin exposure in Egyptian children (n=50, aged 1-2.5 years) by assessing urinary aflatoxin metabolite (AFM(1), AFB(1), AFB(2), AFG(1), AFG(2)) levels. Samples from Guinean children (n=50, aged 2-4 years) were analyzed in parallel providing a comparison to a region of established frequent aflatoxin exposure. Aflatoxins were isolated from urine using C18-cartridges followed by immunoaffinity clean-up, and quantified by HPLC with fluorescence detection. Overall aflatoxins were less frequently present in Egyptian (38%) than Guinean urine samples (86%) (p<0.001), which was particularly related to differences in detection rates of AFM(1) (8% compared to 64%, respectively, (p<0.001)). For AFM(1) the geometric mean level in Guinea (16.3 pg/ml; 95% CI: 10.1, 26.6 pg/ml) was 6-fold higher (p<0.001) than in Egypt (2.7 pg/ml; 95% CI: 2.5, 2.8 pg/ml). Urinary aflatoxins from healthy children in these two regions have not previously been reported, and exposure appears modest in Egypt compared to Guinea. These data suggest that measures to reduce aflatoxin exposure in both regions are important, though particularly in Guinea.     

一例房颤合并冠心病患者初始抗栓治疗策略及文献复习

目的 探讨房颤伴急性冠脉综合征的抗栓治疗策略。方法 1例46岁房颤合并冠心病的男性患者,房颤卒中风险低危,入院期间未给予抗凝治疗,后出现急性脑梗塞。通过提阅部分指南及文献,分析CHA₂DS₂-VAS_c评分为1分,并伴急性冠脉综合征患者的不同抗栓治疗策略方案及其优劣。结果 文献提示,CHA₂DS₂-VAS_c评分为1分出血低危患者,建议尽早服用抗凝药。双联抗栓（华法林+氯吡格雷）能够有效抗栓并且降低患者出血风险,因此需根据患者的具体情况,尽快将三联调整为双联抗栓（1~3个月内）,保证患者疗效的情况下,降低患者出血风险。结论 临床上遇到相关患者需充分评估患者的出血及血栓风险,制定个体化的抗栓治疗策略。     

人参-黄芪药对治疗2型糖尿病作用机制的网络药理学研究

目的采用网络药理学方法研究人参–黄芪药对治疗2型糖尿病的作用机制。方法利用中药系统药理学技术平台(TCMSP)获取人参–黄芪药对的主要成分和对应靶点,通过UniProt和DrugBank数据库查询靶点对应的基因,运用Cytoscape3.6.1构建活性成分–靶点相互作用网络。然后通过TTD、DigSee、CTD多个数据库查询2型糖尿病的相关靶点,与人参-黄芪药对作用靶点取交集后获得人参–黄芪药对–T2DM疾病交集靶点。运用STRING在线数据库构建蛋白相互作用(PPI)网络,最后通过DAVID进行GO功能和KEGG通路富集分析。结果筛选得到41个活性化合物,对应靶点219个,关键靶点涉及PTGS2、PTGS1、ADRB2、NCOA2、SCN5A等。PPI网络包含36个蛋白,包括BCL2、CASP3、CASP8、TGFB1、NOS2、PPARG等。GO功能分析获得269个条目(P0.05),KEGG通路富集得到71条信号通路(P0.05),包括胰岛素抵抗通路、PI3K/Akt信号通路、脂肪细胞因子信号通路等。结论人参–黄芪药对治疗2型糖尿病是多成分、多靶点、多通路协同作用,主要参与炎症反应、细胞凋亡、氧化应激等发挥作用。