Structural requirements of human ether-a-go-go-related gene channels for block by bupivacaine

BACKGROUND: Local anesthetics interact with human ether-a-go-go-related gene (HERG) channels via the aromatic amino acids Y652 and F656 in the S6 region. This study aimed to establish whether the residues T623, S624, and V625 residing deeper within the pore are also involved in HERG channel block by bupivacaine. In addition, the study aimed to further define the role of the aromatic residues Y652 and F656 in bupivacaine inhibition by mutating these residues to threonine. METHODS: Alanine and threonine mutants were generated by site-directed mutagenesis. Electrophysiologic and pharmacologic properties of wild-type and mutant HERG channels were established using two-electrode voltage-clamp recordings of Xenopus laevis oocytes expressing HERG channels. RESULTS: Tail currents at -120 mV through HERG wild-type channels were inhibited with an IC50 value of 132 +/- 22 microm (n = 33). Bupivacaine (300 microm) inhibited wild-type tail currents by 62 +/- 12% (n = 7). Inhibition of HERG tail currents by bupivacaine (300 microm) was reduced by all mutations (P < 0.001). The effect was largest for F656A (inhibition 5 +/- 2%, n = 6) in the lower S6 region and for T623A (inhibition 13 +/- 4%, n = 9) near the selectivity filter. Introducing threonine at positions 656 and 652 significantly reduced inhibition by bupivacaine compared with HERG wild type (P < 0.001). CONCLUSIONS: The authors' results indicate that not only the aromatic residues Y652 and F656 but also residues residing deeper within the pore and close to the selectivity filter of HERG channels are involved in inhibition of HERG channels by the low-affinity blocker bupivacaine.     

Local anesthetic interaction with human ether-a-go-go-related gene (HERG) channels: role of aromatic amino acids Y652 and F656

BACKGROUND: Human ether-a-go-go-related gene (HERG) potassium channels constitute a potential target involved in cardiotoxic side effects of amino-amide local anesthetics. The molecular interaction site of these low-affinity blockers with HERG channels is currently unknown. The aim of this study was to determine the effect of the mutations Y652A and F656A in the putative drug binding region of HERG on the inhibition by bupivacaine, ropivacaine, and mepivacaine. METHODS: The authors examined the inhibition of wild-type and mutant HERG channels, transiently expressed in Chinese hamster ovary cells by bupivacaine, ropivacaine, and mepivacaine. Whole cell patch clamp recordings were performed at room temperature. RESULTS: Inhibition of HERG wild-type and mutant channels by the different local anesthetics was concentration dependent, stereoselective, and reversible. The sensitivity decreased in the order bupivacaine > ropivacaine > mepivacaine for wild-type and mutant channels. The mutant channels were approximately 4-30 times less sensitive to the inhibitory action of the different local anesthetics than the wild-type channel. The concentration-response data were described by Hill functions (bupivacaine: wild-type IC50 = 22 +/- 2 microm, n = 38; Y652A IC50 = 95 +/- 5 microm, n = 31). The mutations resulted in a change of the stereoselectivity of HERG channel block by ropivacaine. The potency of the local anesthetics to inhibit wild-type and mutant channels correlated with the lipophilicity of the drug (r > 0.9). CONCLUSIONS: These results indicate that local anesthetics specifically but not exclusively interact with the aromatic residues Y652 and F656 in S6 of HERG channels.     

Onset and duration of action of vecuronium in the elderly: comparison with adults

The onset and duration of action of vecuronium were studied in young adult (n = 30; mean age 34 +/- 11.1 (s.d.) yr), middle-aged (n = 20; mean age 60 +/- 5.8 yr) and elderly patients (n = 30; mean age 80 +/- 4.6 yr) anaesthetised with thiopentone, nitrous oxide in oxygen and halothane. Neuromuscular block was monitored by applying the train-of-four (TOF) stimulation at 2 Hz to the ulnar nerve every 12 s. Half the patients in each group received 0.08 and the other half 0.12 mg kg-1 of the relaxant. The time to return of T1 (first response in the TOF sequence) to 25% of control was 28 +/- 5.2 (s.d.), 34 +/- 7.1 and 39 +/- 10.2 min following 0.08 mg kg-1 dose (P less than 0.05 between the elderly and young adults) and 45 +/- 9.2, 48 +/- 6.2 and 69 +/- 19.2 min following 0.12 mg kg-1 dose, respectively, in the three age groups (P less than 0.05 between the elderly and the other two groups). The recovery indices (time for 25-75% recovery of T1) after the 0.08 mg kg-1 was 9.6 +/- 3.4, 13.6 +/- 5.1 and 17.4 +/- 6.1 min, respectively (P less than 0.05 between the elderly and young adults). There was no significant difference in any of the parameters between the young adults and the middle-aged. The onset of block at each dose was not significantly different between the three age groups; however, the time to maximum effect was significantly shorter with the higher dose in the young and the middle-aged, but not in the elderly. Regression analysis of the data between age and the duration of action and recovery index suggested a significant prolongation (P less than 0.05) of these parameters in the elderly.     

Recipient conditioning with beagle plasma and beagle liver: prolongation of kidney-graft function without preoperative lymphocytotoxic antibody formation]

Donorspecific recipient conditioning in the non-related beagle produces prolonged kidney-graft survival without any postoperative immunosuppression. Besides 2 donor blood injections on days--18 and--11 followed by a 6-day preoperative immunosuppressive pulse (Procarbazine, ATS) donor plasma and a donor liver preparation are equally active. Additional long-term low dose preoperative immunosuppression with azathioprine tends to strengthen the effect. Lymphocytotoxic antibody formation is avoided in the recipient where no whole blood is used.     

Distinct molecular sites of anaesthetic action: pentobarbital block of human brain sodium channels is alleviated by removal of fast inactivation

Fast inactivation of sodium channel function is modified by anaesthetics. Its quantitative contribution to the overall anaesthetic effect is assessed by removing the fast inactivation mechanism enzymatically. Sodium channels from human brain cortex were incorporated into planar lipid bilayers. After incorporation, channels were exposed to increasing concentrations of pentobarbital (pentobarbitone), either before or after fast inactivation had been enzymatically removed using trypsin. Anaesthetic suppression of these channels with or without the fast inactivation site was compared by analysing single channel currents. Treatment with cytoplasmic trypsin alleviated two-thirds of the pentobarbital block on open channel probability (fractional channel open time). The hyperpolarizing shift in steady-state activation caused by pentobarbital was not affected by treatment with trypsin. Extracellular trypsin was ineffective. These results support a model of general anaesthetic action on sodium channels in which anaesthetics produce a concentration-dependent shift in the distribution between activated and inactivated states towards fast inactivation. Some pentobarbital effects remained after removal of inactivation. The results support a multi-mechanistic model of anaesthetic action on brain sodium channels.      

Bladder perforation: a potential risk of early endovesical chemotherapy with mitomycin C

The use of chemotherapeutic agents in the treatment of superficial bladder cancer is well known. In particular, mitomycin C (MMC) is globally accepted also in the early treatment after an endoscopic resection. Complications related to MMC are usually scarce as a systemic absorption is quite absent, while its use is effective for the bladder recurrence reduction. In our experience we report a female patient with a bladder perforation after an early instillation of a single dose of MMC. In this case, systemic toxicity occurred requiring subintensive care for a complete repair.     

Dosage and duration of medication for men with lower urinary tract symptoms: two questions without definitive answers

PURPOSE OF REVIEW: In this review, the dosage and duration of medication in the management of benign prostatic hyperplasia are discussed. There is no official guideline, however, and even no professional agreement on these points. RECENT FINDINGS: Considering the dosage, dose-titration is probably not a drawback as there is a high risk of undertreatment or overtreatment when using a single dosage for every patient. Duration of treatment is a matter of concern. A quarter of patients discontinue their treatment early. For the others, a long period of treatment may be mandatory for those patients who are at risk of progression. After a course of medication (6 months to 1 year), a trial without treatment may help to decide whether treatment must be continued if symptoms relapse. SUMMARY: For men with lower urinary tract symptoms, there seems to be no definitive answer about the appropriate dosage and duration of medicine.     

新肿瘤标志物—长链非编码RNA分子机制及其与肿瘤关系研究进展

【摘要】〓长链非编码RNA(LncRNA)具有复杂的生物学功能,在多种类型恶性肿瘤组织中表达异常,影响肿瘤细胞的增殖、迁移、侵袭等能力,对肿瘤发生、发展起促进或抑制作用。本文将对LncRNA调控基因表达的分子机制以及与肿瘤关系进展予以综述,为进一步研究LncRNA作为诊断、治疗、预后的新肿瘤标志物奠定基础。     

VP3基因联合吉西他滨诱导人膀胱癌细胞凋亡的实验研究

目的探讨鸡贫血病毒VP3基因在人膀胱癌EJ细胞株中的表达,观察VP3基因联合吉西他滨诱导人膀胱癌EJ细胞株凋亡的效应。方法用真核表达载体PcDNA3-VP3转染人膀胱癌EJ细胞株,利用RT-PCR技术检测VP3基因在EJ细胞中的表达状况。观察VP3基因和10^-7mol／L、10^-8mol／L、10^-9mol／L浓度吉西他滨在体外单独或联合用药对人膀胱癌EJ细胞的增殖活性的影响,检测VP3基因和10^-8mol／L浓度吉西他滨在体外单独或联合用药对人膀胱癌EJ细胞的凋亡作用。结果转染PcDNA3-VP3后VP3基因在EJ细胞中表达。转染重组质粒PcDNA3-VP3、吉西他滨各浓度、VP3基因联合吉西他滨各浓度的EJ细胞株的增殖活性明显下降（P〈0．01）。透射电镜下观察到凋亡细胞的典型形态学特征。TUNAL法检测EJ细胞株凋亡率表现为：转染PcDNA3-VP3组高于对照组（P〈0．01）,10^-8mol／L浓度的吉西他滨组高于对照组（P〈0．01）,联合组高于转染PcDNA3-VP3组（P〈0．01）。结论VP3基因表达能高效诱导人膀胱癌EJ细胞株细胞凋亡,联合10^-8mol／L浓度的吉西他滨能增加VP3基因诱导的人膀胱癌EJ细胞株凋亡。     

CD146 gene expression in clear cell renal cell carcinoma: a potential marker for prediction of early recurrence after nephrectomy

Objectives

To investigate whether CD146 gene expression could provide useful information to predict early recurrence after nephrectomy.

Methods

This study included 84 patients with clear cell renal cell carcinoma (cRCC), and 44 subjects without tumor were used as controls. Quantitative RT-PCR was used to measure the CD146 gene expression.

Results

The mean value of CD146 expression in patients with metastatic cRCC (0.0438?±?0.0024) was significantly higher than in those with localized cRCC (0.0374?±?0.0012, P?=?0.018) or in controls (0.0344?±?0.0010, P?=?0.001). Of patients with localized cRCC, those with recurrence had a significantly higher CD146 expression than those without recurrence (P?=?0.029). The univariate analysis showed that CD146 was associated with early recurrence. The recurrence-free survival curve indicated that patients with a high CD146 expression had a significantly higher recurrence rate than those with a low CD146 expression (P?=?0.018).

Conclusions

CD146 gene expression can be useful for predicting early recurrence and stratifying the patients into risk groups for possible adjuvant treatment.     

Compression with or without early ambulation in the prevention of post-thrombotic syndrome: a systematic review.

INTRODUCTION: The aim of this study was to assess whether there is enough evidence to suggest that compression with or without early ambulation after proximal DVT reduces the risk of post-thrombotic syndrome (PTS). METHODS: Systematic review based on electronic and hand searching of the relevant literature. RESULTS: Four randomized studies were identified and despite the fact that there was lack of uniformity in reporting standards all but one showed significant risk reduction of PTS using compression. No difference in recurrent thromboembolic events (DVT or pulmonary embolism) was observed between the compression and control group. In one study the early outcome from the combination of early ambulation with compression was faster reduction of swelling with better well-being without increased risk of PE compared to the control group. Pooled analysis of all studies showed that PTS developed in 24% (61/254) in the compression group and in 46% (110/239) in the control group (chi2=25.36, p=0.0001; OR: 0.37, 95%CI: 0.25, 0.54; RR: 0.52, 95%CI: 0.40, 0.67; and RRR: 0.48, 95%CI: 0.33, 0.60) with a 48% risk reduction from the use of compression. CONCLUSION: Despite the fact that compression with or without early ambulation appears to be safe and it is more often associated with a decreased rate of PTS, the four existing studies do not permit meaningful data comparison due to lack of uniformity in reporting standards.