急性缺氧对膈肌疲劳的影响

本文观察急性缺氧对犬膈肌疲劳的影响，发现急性缺氧条件下，膈肌疲劳的耐受时间为１８．００±３．７０ｍｉｎ，较对照组４１．３３±５．３０ｍｉｎ明显缩短（Ｐ＜０．０５），而且疲劳膈肌恢复过程中产生跨膈压（ｔｒａｎｓｄｉａｐｈｒａｇｍａｔｉｃｐｒｅｓｓｕｒｅ，Ｐｄｉ）明显低于对照组（Ｐ＜０．０５），证实急性缺氧使膈肌疲劳的耐受性明显下降，且不利于疲劳膈肌肌力的恢复。     

低氧与膈肌疲劳

膈肌疲劳是导致呼吸衰竭发生的重要的病理生理机制之一,低氧对膈肌疲劳的发生发展起着重要的作用。对低氧造成膈肌疲劳的机制和机体对低氧后的适应性改变进行简要的介绍。     

辅酶Q10对兔膈肌疲劳的作用

实验以膈肌肌电图（ＥＭＧｄｉ）及膈肌诱发电位为指标，观察辅助酶Ｑ１０对兔膈肌作用，发现：（１）复制膈肌疲劳（ＤＩＦ）后静脉注射ＣｏＱ１０ｍｇ／ｋｇ，对ＤＩＦ有治疗作用，（２）提前１静脉注射ＣｏＱ１０１０ｍｇ／ｋｇ预处理，对电致作膈肌有保护作用。     

氨茶碱对慢性电刺激后膈肌肌条力学模式的影响

研究氨茶碱对慢性电刺激后兔膈肌肌条力学特征的影响。分别测定正常对照组和CES组加氨茶碱后的颤搐收缩张力（Pt）、峰值张力时间（TPT）、1/2松驰时间（1/2RT）、强直颤搐收缩张力（Po)、疲劳指数（FI）和疲劳恢复指数（FRI）。氨茶碱明显增加CES组Pt和Po,降低FI和FRI,但对10Hz和20Hz组的作用明显强于50Hz和100Hz组。氨茶碱对预防和治疗膈肌疲劳具有一定的临床意义。     

大剂量甲状腺素对大鼠膈肌影响的实验研究

本文采用光镜SDH组织化学方法,透射电镜技术,显微图像分析技术。对给予甲状腺素后大鼠膈肌肌纤维的改变进行了定性和定量的研究。结果发现膈肌三型肌纤维出现不同程度的肌纤维萎缩,SDH活性减弱,含量减少,线粒体肿胀,空泡变性。本研究为甲亢肌病提供了形态学基础,并为甲亢肌病的发病机理提供了有益的参考。     

体外膈肌起搏的临床应用及研究进展

体外膈肌起搏器是我国研制的创新技术产品,主要刺激膈神经引起膈肌收缩.体外膈肌起搏技术应用于临床已有30年历史,研究成果较多,应用范围较广,目前主要应用于呼吸系统疾病治疗.     

膈肌代食管手术可行性的动物解剖学研究

目的　研究猪膈肌的结构和动脉血供,探讨对猪行膈肌代食管手术实验的解剖学可行性并为其提供理论依据。 方法　杂种长白猪6头经动脉灌注明胶-氧化铅混悬液,CT扫描后将图像导入计算机行三维重建,并观察膈肌各条供血动脉的起源、走形、和分支;完整切取膈肌组织行X线摄片,观察各动脉在膈肌上分支、供血范围及相互的吻合;同时对膈肌进行大体解剖和测量。 结果　猪膈肌位置及结构与人类存在部分差异,其血供主要来自肌膈动脉、后肋间动脉、心包膈动脉及膈动脉,其主干和主要分支在重建图像上基本可显示,在X线图上可见其在膈肌上的分支丰富,相互吻合广泛。 结论　从猪膈肌的结构、动脉血供来看,具备作为带蒂组织瓣行食管替代的解剖可行性;而以膈动脉为血管蒂取组织瓣应为该手术最佳选择。     

兔膈肌肌浆网Ca2+-ATPase活性及钙离子的转运

本文分别用定磷法测定兔膈肌SR Ca 2 -APTase 活性、Fura-2 荧光法测定SR Ca 2 释放、摄取动力学和[ 3 H] -Ryanodine 与RyR 结合实验测定SR RyR 的量,分析其功能特性。 结果显示兔隔肌、心肌和骨骼肌SR Ca 2 -APTase 活性分别为70.13 ±8.25、 41.25 ±6.25 和120.17± 17.03 m mol/L pi/mg 蛋白/h1 。膈肌的SRCa 2 -APTase 活性显著高于心肌P<0.01 。但明显低于骨骼肌P<0.01; 膈肌SR Ca 2 释放量和摄取速度显著快于心肌（P<0.01）,但明显低于骨骼肌（P<0.01）;膈肌SR RyR 同[ 3 H] Ryanodine 的最大结合值（Bmax）是0.78 ±0.05pmol/mg 蛋白,其解离常数（KD）是6.93 1.13nmol/L,分别位于心肌和骨骼肌范围内。本文认为膈肌Ca 2 释放单位、SR Ca 2 -APTase 和SR Ca 2 释放摄取动力学分别具有心肌和骨骼肌的一些特征,其Ca 2 释放可能具有变构偶联和CICR 偶联两种形式,心肌型DHPR 亚型,RyR 3 和SERCA 2 a 的存在可能是膈肌ECC 依赖于细胞外Ca 2 的主要原因。     

颤搐性气道内压对膈肌功能的评价作用

目的:探讨颈部膈神经根磁波刺激诱发的颤搐性气管内压［Ptra(t)］ 对膈肌功能的评价作用。 方法： 对10例因腹部手术需要全麻患者，在全麻前、全麻中观察磁波刺激膈神经诱发的Ptra(t)、颤搐性口腔压［Pm(t)］和颤搐性跨膈压［Pdi(t)］的动态变化规律。结果:(1)Pm(t)测定值不稳定，与Pdi(t)的变化不一致；Ptra(t)的变化与Pdi(t)的变化一致。(2)全麻前、中和复苏后的Pdi(t)分别为:（21.4±5.0）cmH2O、(8.7±3.1) cmH2O和（22.9±7.6）cmH2O,全麻中降低（56.8±20.5）%,明显低于全麻前（P<0.01），而复苏后与全麻前没有统计学差异。(3)Ptra(t)与Pdi(t)呈高度线性关系(r=0.802，P<0.01)。(4)Ptra(t)/Pdi(t)的比值为（1.07±0.18），其变异系数为（CV）（10.67±4.03）%。 结论:Ptra(t)可用于动态监测气管插管或气管切开患者的膈肌功能。     

Biometric approximation of diaphragmatic contractility during sustained hyperpnea

Imposing load on respiratory muscles results in a loss of diaphragmatic contractility that develops early, is independent of task failure, and levels off following the initial decrease. This study assessed the progression of diaphragmatic contractility during sustained normocapnic hyperpnea and applied a biometric approximation (hypothesis: non-linear decay). Ten healthy subjects performed three consecutive hyperpnea bouts (I:6 min warm up/II:9 min/III:task failure 28.6 ± 11.5 min; mean ± SD) at maximal voluntary ventilation fractions (I:30-60%/II:70%/III:70%), followed by recovery periods (I:18 min/II:6 min/III:30 min). Twitch transdiaphragmatic pressure (TwPdi) was assessed throughout the protocol. Bouts II and III induced diaphragmatic fatigue (TwPdi baseline vs. Recovery -19 ± 17% and -30 ± 16%, both p < 0.05 RM-ANOVA) while bout I did not. During sustained hyperpnea (II/III), TwPdi followed an exponential decay (r(2) = 0.91). The reduction in diaphragmatic contractility closely follows a non-linear function with an early loss in diaphragmatic contractility during sustained hyperpnea, levels off thereafter, and is independent of task failure. Thus, reasons other than diaphragmatic fatigue are likely to be responsible for task failure during sustained hyperpnea.     

Effect of lung volume reduction surgery for emphysema on diaphragm function

Preoperative prediction of a successful outcome following lung volume reduction surgery (LVRS) for emphysema is imperfect. One mechanism could be improvement in respiratory muscle function yet controversy exists regarding the magnitude and mechanism of such an improvement. Therefore, we measured diaphragm strength in 18 patients before and after LVRS. Mean (S.D.) FRC fell from 6.53 to 5.40 l (p = 0.0001). Mean sniff transdiaphragmatic pressure increased from 76 to 87 cm H2O (14%, p < 0.03) and mean twitch transdiaphragmatic pressure (Tw Pdi) increased by 2.5 cm H2O at 3 months (12%, p = 0.03). There was a highly significant increase in twitch esophageal pressure (Tw Pes) (60%, p < 0.0001), which was maintained at 12 months (46% increase, p = 0.0004). No change was observed in quadriceps twitch tension in nine subjects in whom it was measured. After LVRS the ratio Tw Pes:Tw Pdi increased from 0.24 to 0.37 at 3 months (p = 0.0003) and 0.36 at 12 months (p = 008). Low values of Sn Pdi, Sn Pes, Tw Pes and a high RV/TLC ratio were the preoperative variables most predictive of improvement in shuttle walking distance. We conclude that LVRS improves diaphragm function primarily by alteration of lung volume. Patients with poor diaphragm function and high RV/TLC ratio preoperatively are most likely to benefit from the procedure.     

Effect of expiratory resistive loading on inspiratory and expiratory muscle fatigue

Inspiratory and expiratory pressures are increased during expiratory resistive loading (ERL). We asked whether ERL elicits inspiratory as well as expiratory muscle fatigue. On four separate days, seven male subjects underwent ERL to task failure. Subjects maintained respiratory frequency at 15 breaths min⁻¹, expiratory gastric pressure at 40% or 60% of maximum, and expiratory duty cycle at 0.4 or 0.7 (ERL_40%0.4, ERL_40%0.7, ERL_60%0.4, ERL_60%0.7). Inspiratory and abdominal muscle contractility was assessed before and up to 30 min after ERL by measuring transdiaphragmatic twitch pressure (P_di,tw) and gastric twitch pressure (P_ga,tw) in response to magnetic nerve stimulation. After each trial, P_di,tw and P_ga,tw were reduced below baseline values (−9 to −15% for P_di,tw and −15 to −22% for P_ga,tw; P < 0.05). The severity of diaphragm fatigue was unaffected by expiratory pressure production or expiratory duty cycle, whereas extending the expiratory duty cycle increased the severity of abdominal muscle fatigue. In conclusion, ERL elicits contractile fatigue of the diaphragm and the abdominal muscles.     

Molecular mechanisms of azole resistance in Candida tropicalis isolates causing invasive candidiasis in China

ObjectiveWe investigated molecular mechanisms responsible for azole resistance in Candida tropicalis isolates.MethodsWe studied 507 C. tropicalis isolates causing invasive candidiasis from ten hospitals over 5 years. Antifungal susceptibility was determined by broth microdilution methods. Point mutations in the C. tropicalis ERG11 gene that may confer azole resistance were explored and verified. The expression levels of ERG11, CYTb, MDR1 and CDR1 genes were compared in 20 fluconazole-susceptible and 20 fluconazole-resistant isolates.ResultsFluconazole-susceptible, -susceptible dose-dependent and -resistant strains accounted for 76.7% (389/507), 10.5% (53/507) and 12.8% (65/507) of C. tropicalis isolates, respectively. The ERG11 mutation A395T/W occurred in 10.7% (54/507) of isolates, all of which were resistant to fluconazole. The nucleotide mutation C461T/Y was the second most common (50/507 isolates, 9.9%), and all isolates carrying C461T/Y also had the mutation A395T/W. However, the presence of C461T did not contribute to the azole-resistant phenotype. Substitutions V125A, Y257H and G464S (<2% of isolates), which were reported for the first time in C. tropicalis, also conferred fluconazole non-susceptible phenotypes. Compared with fluconazole susceptible isolates, fluconazole-resistant isolates had higher ERG11 (fold expression level 1.42 versus 0.79, p < 0.01) but lower CYTb (fold expression level 1.26 versus 2.67, p < 0.01) gene expression levels. Three azole-resistant isolates carrying the wild-type ERG11 gene had higher levels of CDR1 and MDR1 expression.ConclusionsERG11 missense mutations were the major mechanism responsible for azole resistance in C. tropicalis isolates, but overexpression of ERG11, CDR1 and MDR1, as well as reduced expression of CYTb, also contributed to resistance.     

胰十二指肠切除术病人胃电图变化

通过对胰十二指肠切除术病人手术前后体表胃电图的研究，探讨手术对病人胃电及排空功能的影响。结果表明：保留幽门的胰十二指肠切除术病人术前６０％存在胃律紊乱及胃排空障碍，８０％此类病人术后出现胃电及胃排空异常。上述结果提示：对拟行保留幽门的胰十二指肠切除术病人术前胃电图检查表现胃节律紊乱及胃排空障碍者，术中应考虑胃及空肠造瘘。     

The direct demonstration of histamine release in allergic reactions in the skin using a skin chamber technique.

We have adapted a skin chamber technique to permit sampling of fluid at the skin window sites of pollen antigen-induced allergic reactions. Low background levels of histamines are formed in control chambers, whereas significantly increased (p less than 0.01) amounts are found within 30 min following ragweed application in sensitized subjects.     

The cardiac responses of schizophrenics to orienting, signal and non-signal tones.

The cardiac responses of schizophrenics were examined under three conditions: (1) to repeated 75 dB, 1000 Hz (orienting) tones of no attentional significance; (2) to 75 dB, 1000 and 2000 Hz tones presented randomly and requiring a motor response to the 1000 Hz (signal) tone; (3) to 85 dB, 1000 Hz orienting tones. Responses of non-psychotic psychiatric patients were examined to the 75 dB tones. All patients were subdivided upon the basis of electrodermal responsivity during conditions (1) and (3), into groups of responders - no habituation of responses; non-responders - no responses; habituators - responses habituated to criterion. All groups exhibited a decelerative response with a latency of less than 1 sec. The groups were differentiated by the second component of the response to the orienting tones: responders - acceleration; habituators - deceleration; non-responders - predominantly no response. All exhibited accelerative responses to the signal tones. Parallels between cardiac and electrodermal responsivity are outlined.     

Effect of moderate malnutrition on immediate hypersensitivity and immunoglobulin E levels in asthmatic children

Dermal reactions and IgE levels were compared in 51 asthmatic Colombian children identified on the basis of anthropometric measurements as nutritionally normal (25) or mildly (16) or moderately (10) undernourished. Twenty-five nonatopic children served as controls. Total serum IgE concentrations were significantly elevated in the asthmatic group as a whole. Moderately malnourished (grade 11) asthmatic children had more than twice as much serum IgE as normal or mildly malnourished (grade I) asthmatic subjects and seven times more than nonatopic children. Intestinal parasitism did not appear to contribute to these differences in IgE levels. Serum levels of IgA and IgD were similarly elevated in grade II asthmatics. Concentrations of serum IgG, IgM, and C3 and C4 complement were unaffected by nutritional or allergic status. Eosinophilia in nasal mucus was significantly reduced in grade I and grade II malnourished asthmatic children. Among asthmatics, the most frequent dermal reactions were to mite antigens (96%), house dust (67%), and grass pollens (35%). Significant levels of specific IgE were detected by the RAST to two species of mites in nearly all atopic children. There was no apparent influence of nutritional status on the distribution of reactivity to a particular allergen by either dermal reactivity or specific IgE assay. The clinical significance of hyper immunoglobulin E in atopic, moderately malnourished children remains to be elucidated.