反相高效液相色谱法测定人体血浆中克拉维酸钾羟氨苄青霉素的含量

目的 :采用反相高效液相色谱法同时测定服用克拉维酸钾羟氨苄青霉素颗粒剂和片剂后人血浆中的克拉维酸和羟氨苄青霉素的浓度。方法 :以ODS柱为分析柱 ,磷酸盐缓冲液 -三乙胺缓冲液 -甲醇 ( 87∶1 3∶2 5) ,用磷酸调 pH至 3作流动相 ,柱温 :3 5℃ ;检测波长 :2 2 2nm。 结果 :本法中羟氨苄青霉素的平均回收率为 99 0 1 %～ 99 75% ,RSD为 1 7%～ 3 2 % ;克拉维酸钾的平均回收率为 97 95%～ 1 0 0 0 % ,RSD为 0 8%～ 2 0 %。 2种药物的日内和日间RSD小于 6 4 % ,血浆中的标准曲线相关良好 ,克拉维酸和羟氨苄青霉素在血浆中的最低检测浓度分别为 0 2 4和 0 2 5μg·mL- 1。结论 :以此条件可对克拉维酸钾羟氨苄青霉素进行药代动力学参数研究     

Tissue potassium,selenium, and iron levels associated with gastric cancer progression

The contents of 10 minor and trace elements in histologically confirmed gastric adenocarcinomas and their corresponding normal gastric mucosal tissues obtained from 39 patients at the time of gastric resection were simultaneously determined by instrumental neutron activation analysis. Specimens were irradiated by reactor neutrons and subsequently subject to direct analysis using a high-resolution HPGe -spectrometer. Univariate analysis revealed that gastric cancer tissues had significantly higher concentrations of Fe, K, Mg, Na, Rb, Se, and Zn than normal gastric mucosal tissues. However, multivariate analysis found that Fe, K, and Se were independent elements that associated with gastric cancer. Upon further evaluation of their clinical significance, we found a high tissue K level was related to lymphatic duct metastasis. High Se tissue levels were linked to intestinal type adenocarcinoma. A positive correlation was found between high Fe levels and vascular involvement. These findings suggest that Fe and K are associated with gastric cancer progression. Se is involved in carcinogenesis of stomach in high-risk areas. The mechanisms that underlie the corresponding pathohistological features deserve further study.     

The influence of external sodium and potassium on lithium uptake by primary brain cell cultures at ‘therapeutic’ lithium concentration

The ionic regulating of lithium homeostasis and steady-state intra: extracellular lithium distribution in the brain can be approached by experimental methods using intact nerve cells in vitro. Primary cultures prepared from chick embryonic brain were applied to study the effect of extracellular sodium and potassium on the lithium uptake of nerve cells at therapeutic lithium concentration (1.5 mM). Lithium influx and the level of steady-state intracellular lithium were significantly reduced by increasing the external sodium concentration. At physiological extracellular sodium level, the steady-state content of lithium in the brain cells was about half of that observed in the presence of 10 mM sodium in the incubation media and the value of the intra: extracellular lithium distribution ratio was below 1. External potassium (0.5–3 mM) strongly inhibited lithium uptake of the nerve cells. Ouabain (10^-4 M) had no effect on this potassiumsensitive lithium uptake in Tyrode media. Sodium influx studied by isotope tracer methodology was higher in cultures preloaded with lithium as compared to that of the controls. It can be concluded that sodium and potassium ions, at physiological concentrations, significantly influence lithium uptake as well as the intra: extracellular lithium distribution in brain cell cultures.     

The cardiotonic bipyridine AWD 122-60 inhibits adenosine triphosphate-sensitive potassium channels of mouse skeletal muscle

Summary The inhibition of ATP-sensitive potassium channels in mouse skeletal muscle by the cardiotonic bipyridine AWD 122-60 was investigated with the patch-clamp technique. In excised patches of the inside-out configuration, internally applied AWD 122-60 (10^–6–10^–3 mol/1) reversibly reduced the open-probability of single ATP-sensitive potassium channels. The agent shortened the periods of channel activity but did not affect the channel conductance. At positive membrane potentials channel inhibition by AWD 122-60 was more pronounced than at negative potentials, the drug concentrations producing 50% channel inhibition were 11 mol/l at + 40 mV and 29 mol/l at –40 mV. The Hill coefficients of the concentration-response curves were in the range between 0.5 and 0.6 for both potentials. milrinone (10^–4 mol/I), had no effects on ATP-sensitive potassium channels in skeletal muscle. potassium channels in heart muscle by AWD 122-60 are discussed. Send offprint requests to B. Neumcke at the above address     

Citrate and recurrent idiopathic calcium urolithiasis

Summary In idiopathic recurrent calcium urolithiasis (RCU) in men (n=37) the metabolic effects of oral tripotassium citrate (PC) were investigated in a longitudinal field study. The patients were either normo- (n=22) or hypocitraturic (n=15). Laboratory examinations were performed before, and after 3, 6, and more than 12 months of medication. Acceptance of PC was poor, mainly because of the salty taste of the tablet preparation chosen, and a number of participants dropped out of the study. In the remaining participants, compliance was acceptable when evaluated on the basis of urinary potassium and undesired side effects did not occur. In the short term (up to 3 months), PC evoked compensated metabolic alkalosis (pH and citrate in urine increased; blood gases remained normal), a drop in urinary calcium, together with increasing oxaluria, hydroxyapatite supersaturation, and calcium phosphate crystalluria. In the long term (>12 months) PC urinary pH and citrate dissociated, in that pH returned to pretreatment baseline values, whereas citrate stayed at high levels. In normocitraturics but not in hypocitraturics, urinary urea and sodium in creased with PC. Hypocitraturics appeared to be less sensitive to the effects of PC, as reflected by the relatively small rise in urinary pH and citrate, and they maintained higher mean levels of indicators of bone metabolism (osteocalcin, alkaline phosphatase, hydroxyproline) despite continuous administration of PC. It was concluded that although the PC tablet preparation was effective it may not be an ideal anti-stone drug treatment in the long term and that, especially in hypocitraturiecs, the intrinsic metabolic defect of RCU may not be sufficiently well controlled.     

Flurazepam interaction with sodium and potassium channels in squid giant axon

External application of 0.05-1.0 mM flurazepam was found to partially block both sodium and potassium currents in voltage-clamped squid giant axons. At the same concentration the fractional block of the potassium current was found to be 3 times greater than that of the sodium current. In the presence of the drug the potassium current appeared to "inactivate', as flurazepam block became more profound during the course of the depolarization. The decay of the potassium current can be explained by a model in which flurazepam enters and blocks the potassium channels only after they have opened. Once bound in the potassium channel, removal of flurazepam from its binding site develops slowly (tau = 48 ms). Thus repetitive stimulation of the nerve produced a cumulative block. When applied inside the axon flurazepam was found to be 1.5 (n = 4) times more potent blocker of potassium channels than following external application. This result suggests that when applied externally, a neutral form of the drug diffuses across the membrane and blocks occurs from the inner end of the channel.     

赖诺普利与氯沙坦预防压力负荷性心肌肥厚的实验研究

目的 探讨大鼠心肌肥厚时心血管重构的结构、生化改变及赖诺普利与氯沙坦对心血管重构的预防作用。方法 膈下腹主动脉缩窄法建立大鼠心肌肥厚模型。假手术组、模型组、降压和非降压剂量赖诺普利与氯沙坦在术后第2天用药至30天后，检测平均动脉压(MAP)、心肌肥厚程度及局部心肌组织一氧化氮(N0)、一氧化氮合酶(NOS)和胶原蛋白含量。结果 (1)与假手术组相比，模型组MAP、左室重量(LVW)、左室重量指数(LVMI)、心肌细胞横径(TDM)、胶原蛋白分别提高28．6％、20．5％、26．9％、17．9％、54．4％(P＜0．01)；NO、NOS分别降低53．4％、51．2％(P＜0．01)。(2)降压剂量赖诺普利与氯沙坦和非降压剂量氯沙坦干预后，LVW、LVMI、TDM、NO、NOS、胶原蛋白含量与假手术组无明显差异。非降压剂量赖诺普利可使LVW、LVMI和TDM下降，但仍高于假手术组(P＜0．01)，NO、NOS改善不明显；(3)LVMI与MAP、胶原蛋白含量均呈正相关(分别为γ=0．7841，γ=0．8177，P＜0．01)，与NO显负相关(γ=-0．7730，P＜0．01)。结论 心血管重构与血压、心脏间质成分及NO有密切关系；赖诺普利预防心肌肥厚可能是血流动力学和非血流动力学因素共同作用的结果；氯沙坦可能主要依靠非血流动力学因素抗心肌肥厚。     

A novel conotoxin inhibiting vertebrate voltage-sensitive potassium channels.

Toxins from cone snail (Conus species) venoms are multiple disulfide bonded peptides. Based on their pharmacological target (ion channels, receptors) and their disulfide pattern, they have been classified into several toxin families and superfamilies. Here, we report a new conotoxin, which is the first member of a structurally new superfamily of Conus peptides and the first conotoxin affecting vertebrate K+ channels. The new toxin, designated conotoxin ViTx, has been isolated from the venom of Conus virgo and comprises a single chain of 35 amino acids cross-linked by four disulfide bridges. Its amino acid sequence (SRCFPPGIYCTSYLPCCWGICCSTCRNVCHLRIGK) was partially determined by Edman degradation and deduced from the nucleotide sequence of the toxin cDNA. Nucleic acid sequencing also revealed a prepropeptide comprising 67 amino acid residues and demonstrated a posttranslational modification of the protein by releasing a six-residue peptide from the C-terminal. Voltage clamp studies on various ion channels indicated that the toxin inhibits the vertebrate K+ channels Kv1.1 and Kv1.3 but not Kv1.2. The chemically synthesized product exhibited the same physiological activity and identical molecular mass (3933.7 Da) as the native toxin.     

菲啰啉对不同氧化剂和多柔比星所致CHL细胞DNA链断裂的影响

目的 为了研究菲啰啉对2种氧化剂和抗癌药多柔比星诱发细胞DNA损伤的影响, 并初步探讨其损伤机制。方法 用不同浓度菲啰啉预处理CHL细胞30 min, 再分别加入3种不同染毒受试物,共同培养一定时间(0.3 mmol·L^-1重铬酸钾：105 min； 0.5 μmol·L^-1多柔比星：5 min； 0.4 mmol·L^-1过氧化氢(H₂O₂)：25 min)后, 用碱性单细胞凝胶电泳方法(ASCGE)测定DNA链断裂情况, 并同时以菲啰啉与二甲亚砜(DMSO，0.33 mol·L^-1)比较对H₂O₂致DNA损伤中·OH的产生和清除。结果 3种染毒受试物均可明显引起CHL细胞DNA链断裂；而当3 μmol·L^-1菲啰啉预处理后, 可使重铬酸钾、H₂O₂所致DNA迁移长度和细胞拖尾率明显降低, 并超过DMSO降低H₂O₂的损伤作用, 当菲啰林浓度升至12 μmol·L^-1时, 可完全消除这两种因素所致的DNA链断裂损伤；10 μmol·L^-1菲啰啉可抑制多柔比星所致DNA损伤, 但浓度直至60 μmol·L^-1仍不能完全消除多柔比星的损伤作用。结论 菲啰啉对2种氧化剂和多柔比星所致DNA损伤均有不同程度的防护作用,同时提示重铬酸钾和H₂O₂所致的DNA损伤主要与需过渡金属离子参与的·OH产生有关, 而多柔比星所致损伤仅部分与此有关。     

钾通道阻滞剂对大鼠支气管平滑肌细胞增殖的影响

目的探讨电压依赖性延迟整流钾通道(K_V)、Ca²⁺激活钾通道(K_Ca)和ATP敏感性钾通道(K_ATP)对大鼠支气管平滑肌细胞(BSMC)增殖的影响。 方法应用免疫细胞化学、MTT微量比色分析法及流式细胞术,观察K_V,K_Ca和K_ATP对培养中大鼠BSMC增殖的影响。结果K_V阻断剂4-氨基吡啶(4-AP)显著促进大鼠BSMC增殖细胞核抗原的表达,提高BSMC吸光度值,使S+G₂M期细胞数显著增多,并显著提高基础状态下BSMC内Ca²⁺浓度,而K_Ca阻断剂四乙铵(TEA)和K_ATP阻断剂格列本脲(Glib)均无此效应。 结论大鼠BSMC K_V活性的抑制,可提高细胞内Ca²⁺浓度,促进细胞的增殖,而K_Ca和K_ATP对BSMC的增殖均无明显影响。