EFFECTS OF BKCa CHANNELS ON THE REDUCTION OF CYTOSOLIC Ca2+ IN cGMP-INDUCED RELAXATION OF GUINEAPIG TRACHEA

1. In order to examine the mechanisms of cGMP-induced relaxation in airway smooth muscle, the effects of atrial natriuretic peptide (ANP) and 8-brom cGMP on muscle tone were studied by measuring isometric tension, while the effects on cytosolic Ca²⁺ concentrations were studied by measuring the spectra of fura-2 loaded in guinea-pig tracheal strips. 2. Atrial natriuretic peptide and 8-brom cGMP caused a concentration-dependent inhibition of spontaneous tone in the guinea-pig trachea. The relaxant effects of these agents on spontaneous tone were markedly suppressed in the presence of iberiotoxin (IbTX), a selective inhibitor of large-conductance Ca²⁺-activated K⁺ (BKca) channels. Iberiotoxin (30 nmol/L) markedly affected the maximal effect induced by ANP and 8-brom cGMP and augmented EC₇₀ values for ANP and EC₅₀values for 8-brom cGMP approximately 27- and 17-fold, respectively. The inhibitory effects of IbTX on relaxation induced by these agents were diminished in the presence of 1 μmol/L nifedipine, an antagonist of voltage-operated Ca²⁺channels (VOCC). 3. The inhibitory action of ANP and 8-brom cGMP on spontaneous tone was not affected by the presence of 10 μmol/L glibenclamide, an inhibitor of ATP-sensitive K⁺ channels, and 100 nmol/L apamin, an inhibitor of small-conductance Ca²+-activated K⁺ channels. When these agents were applied to tissues precontracted by high (40mmol/L) K⁺, the relaxant effects of these agents markedly diminished. 4. The extracellular Ca²⁺-dependent contraction was inhibited in the presence of 0.3 μmoI/L ANP or 0.1 mmol/L 8-brom cGMP. Concentration—response curves to extracellular Ca²⁺ (0.03—2.4 mmol/L) were markedly diminished by exposure to these agents. The maximal effect induced by extracellular Ca²⁺ was affected by these agents. 5. Atrial natriuretic peptide caused an inhibition of spontaneous tone accompanied by a reduction in the intracellular Ca²⁺ concentration. In the presence of IbTX, the elimination of both muscle tone and cytosolic Ca²⁺ by ANP was suppressed. 6. We conclude that ANP and 8-brom cGMP activate BKca channels and that the inhibition of Ca²⁺ influx through VOCC, mediated by BKca channel activation, may be involved in cGMP-dependent bronchodilation.     

p53 Protein expression in laryngeal squamous cell carcinomas bearing wild-type and mutated p53 gene

We performed an immunohistochemical analysis to investigate the expression of p53 protein in a panel of 18 laryngeal squamous cell carcinomas, 15 primary tumours and three in relapse, previously analysed by us for the presence of p53 gene mutations. Dysplastic and/or normal surrounding mucosa was evaluated in 15 different tumours. The results of our study are the following: (1) expression of p53 protein was observed in one out of five tumours positive for p53 gene mutations (20%) and in 10 out of 13 (80%) negative cases; (2), p53 protein over-expression was frequently observed in normal and/or dysplastic mucosa surrounding either wild-type (7/11) or mutated p53 tumours (2/4); (3), p53 immunoreactive cells showed a pattern of distribution in normal and mildly/moderately dysplastic mucosa (basal layers), different from that in severely dysplastic mucosa (whole thickness). These data further support the hypothesis that p53 protein over-expression may be a marker of the earliest phases of multistep tumorigenesis in laryngeal squamous cell carcinoma.     

喉癌组织T淋巴细胞亚群与外周血前列环素及血栓素的检测

目的 探讨喉癌局部组织的细胞免疫状态与前列腺素类物质前列环素及血栓素的关系。方法 应用免疫组化法检测了28例喉鳞癌患者局部组织内淋巴细胞亚群的分布状况，并与该患者残喉健康侧组织及喉良性肿瘤患者的瘤组织进行对比；同时采用放射免疫分析法分别检测了上述喉鳞癌、喉良性肿瘤患者和正常人血浆前列环素(PGI2)及血栓素A2(TXA2)的含量，并以它们在健康人血浆中的含量为正常对照。结果 喉癌组织内浸润的CD4和CD8细胞数明显升高，而且CD8细胞多于CD4细胞，提示喉癌组织局部的细胞免疫功能受抑。同时喉癌患者血浆中PGI2和TXA2的稳定代谢产物6-酮-前列腺素F1α及血栓素B2(TXB2)的含量高于正常对照组，以TXB2升高更明显。结论 喉癌患者体内前列腺素类物质PGI2／TXA2与其癌组织局部细胞免疫受抑有关，因而可作为生物学标记提示喉癌组织局部的细胞免疫功能状态。     

喉癌患者血小板聚集功能的测定

目的 探讨喉癌与血小板聚集功能的关系。方法 采用比浊法，对50例喉癌患进行血小板聚集功能的检测并以良性肿瘤病人、喉慢性炎性疾病病人及正常人作为对照，应用SAS计算机系统进行分析。结果 与其他组病人相比，喉癌组血小板聚集功能增强并且随着临床分期的增高有增强趋势。结论 喉癌病人的血小板聚集功能有一定的增强；测定血小板聚集功能对恶性肿瘤的疗效判定、预后评估及预测转移有一定的意义；血小板抑制剂有望成为治疗肿瘤的新方法。     

Demonstration of human papillomavirus types 6 and 11 in juvenile laryngeal papillomatosis by in-situ DNA hybridization

A study is reported in which an in situ hybridization technique for the demonstration of human papillomavirus (HPV) employing a biotin--streptavidin polyalkaline phosphatase complex has been successfully applied to formalin-fixed paraffin-processed tissue obtained from ten patients with juvenile laryngeal papillomatosis. In all cases, positive results were obtained for either HPV type 6 or 11. Normal vocal cord epithelium was negative.     

A clinical comparison of the Laryngeal Tube™ and the Laryngeal Mask™ in spontaneously breathing anesthetized patients

Abstract: Background: The laryngeal mask airway (LMA) can be used in general anaesthesia without neuromuscular block. The laryngeal tube (LT) is a new airway device with similar airway features as LMA. LT is provided with a distal cuff to prevent regurgitation. In this study we compared the LMA and LT concerning patient and user aspects. Methods: Sixty patients with ASA (American Society of Anestesiologists) score 1–2 scheduled for minor surgery were randomized to be ventilated either through LMA or LT. After insertion, the number of insertion attempts, and “positioning” and “airway-assessment” was evaluated. The patients reported on “sore throat” after 30 and 60 minutes and the day after anaesthesia. Results: Gender and mean age were equal in both groups. The first insertion attempt was successful in 25 of 28 patients randomised to LMA and in 23 of 27 patients randomised to LT. LMA was evaluated to be easier in “positioning” whereas no difference in “sore throat” was reported. Conclusion: We found no difference between the LMA and the LT in terms user and patient friendliness and safety.     

Keratin 13基因在喉癌发生中的作用

探讨keratin 13基因在喉癌发生中的作用。方法在keratin 13基因内部及附近选择5个微卫星引物进行LOH分析，于DNA水平间接检测100例喉癌患者中该基因的缺失情况。结果5个STR位点均存在LOH，其中D17S1964E、D17S2092、D17S791、D17S1665及D17S808位点的LOH频率分别为30．48％、26．02％、21．62％、37．66%和21．51％，以D17S1665位点的LOH频率最高，杂合性丢失与临床分期无显著相关。结论Keratin13基因在喉癌的发生中具有重要作用，具体机制有待进一步研究。