Reflex Cardiorespiratory Effects of Nociceptive Oesophageal Distension in the Decerebrate Rat

It is well established that painful distension of hollow viscera such as the oesophagus can evoke a reflex tachycardia and pressor response; however, the nature of the oesophageal afferent pathway(s) remains controversial. This study investigated the afferent arc which mediates these reflex cardiovascular changes in the decerebrate rat. In addition, the effect of oesophageal distension on the respiratory activity of the costal diaphragm was studied. Focal distension of the oesophagus (volume of 0.3 ml applied for 10 s) just above the diaphragmatic hiatus evoked a reproducible pressor response and tachycardia in the decerebrate rat. Respiration was transiently inhibited at the beginning of oesophageal distension and prior to the rise in blood pressure. Neuromuscular blockade with the nicotinic acetylcholine receptor blocker alpha-bungarotoxin (140 microg bolus) had no effect on the magnitude of the cardiovascular response. Therefore the efferent supply to the striated muscle of the rat oesophagus was not essential in mediating this reflex. Signal averaging of the mean blood pressure response showed that neither selective ablation of oesophageal spinal afferents nor bilateral vagotomy altered the early trajectory of the pressure response. Bilateral vagotomy reduced the peak magnitude of the response to sustained oesophageal distension. In contrast, selective removal of spinal afferents had no effect on the response. Ablation of both neural pathways was essential to abolish the reflex cardiovascular and respiratory responses. It can be concluded that both vagal and spinal afferent pathways are utilised in the reflex cardiorespiratory response to painful oesophageal distension. Although ablation of one neural pathway had no effect on the response it was still implicated in the reflex, since ablation of both pathways was necessary to prevent the cardiorespiratory changes. This study emphasises the need for caution when inferences are made concerning single selective ablations of multiply innervated organs.     

Factors influencing the variations of ejection fraction during exercise in chronic aortic regurgitation

The influence of left ventricular volume variations and regurgitant fraction variations upon left ventricular ejection fraction, during exercise was examined using equilibrium radionuclide angiography in patients suffering from aortic regurgitation. Ejection fraction (EF), regurgitant fraction (RF), end diastolic volume (EDV) and end systolic volume (ESV) variations from rest to peak exercise were determined in 44 patients suffering from chronic aortic regurgitation (AR) and in 8 healthy volunteers (C). In C, EF increased (+0.10±0.03, P<0.01) and ESV decreased significantly (-23%±12%, P<0.01) RF and EDV did not vary significantly. In AR patients, EF, EDV and ESV did not vary significantly because of important scattering of individual values. Changes in EF and ESV were inversely correlated (r=-0.79, P<0.01) and RF decreased significantly (-0.12±0.10, P<0.01). Volumes and EF changes during exercise occurred in three different ways. In a 1st subgroup of 7 patients, EF increased (+0.09±0.03, P<0.05) in conjunction with a reduction of ESV (-24%±12%, P<0.05) without a significant change in EDV. In a 2nd group of 22 patients. EF decreased (-0.04±0.07, P<0.01) in association with an increase in ESV (+17%±16%, P<0.01) and no change in EDV. In a 3rd subgroup of 15 patients, EF decreased (-0.02±0.06, P<0.01) despite a reduction in ESV (-7%±6%, P<0.01) because of a dramatic EDV decrease (-10%±6%, P<0.05). In this subgroup, changes in EF were inversely correlated with changes in ESV (r=-0.55, P<0.01) and positively related to EDV variations (r=0.42, P=0.02). EDV related to EDV variations (r=0.42, P=0.02). EDV changes were weakly, but significantly, correlated to RF decrease (r=0.39, P<0.05). We conclude that changes in left ventricular ejection fraction during exercise in patients with chronic aortic regurgitation are significantly related in some patients to changes in ventricular loading conditions as well as contractile state. Therefore, a correct interpretation of EF changes during exercise requires the simultaneous determination of changes in LV volumes.Abbreviations EDV end diastolic volume - EF ejection fraction - ESV end systolic volume - LV left ventricle - RV right ventricle     

Eleventh international Argos proceedings: critical decision making in degenerative spinal stenosis

The eleventh Argos international symposium was held on 25 and 26 January 2007 at Maison des Arts et Métiers, Paris. Regular attendees were present as well as newcomers from around the world.     

Features of the metabolic syndrome of "hypertriglyceridemic waist" and transplant coronary artery disease.

BACKGROUND: This study evaluated the prevalence of the atherogenic metabolic triad and the hypothesis that waist circumference and fasting triglyceride concentrations could be used as screening tools for identification of the atherogenic metabolic triad in a population of heart transplant men. It also evaluated the relationship between the atherogenic metabolic triad and coronary artery disease (CAD). METHODS: In the study group of 83 consecutive male heart transplant patients having their routine annual coronarography, 23 patients (28%) were characterized by the atherogenic metabolic triad defined by the presence of elevated fasting insulin and apolipoprotein B concentrations and by small low-density lipoprotein (LDL) particles. RESULTS: Seventy-seven per cent of patients with waist circumference values >/= 90 cm and with elevated triglyceride levels (>/=2.0 mmol/liter) were characterized by this atherogenic metabolic triad. Patients with the atherogenic metabolic triad were at markedly increased risk of CAD (odds ratio of 25.3, 95% CI: 1.11-577.3, p < 0.04) compared to heart transplant patients without the atherogenic metabolic triad. CONCLUSIONS: About 30% of heart transplant patients showed the features of the atherogenic metabolic triad. Measurement and interpretation of waist circumference and fasting triglycerides could be used among heart transplant patients to early identify men characterized by the presence of elevated fasting insulin and apolipoprotein B concentrations and small LDL particles. The presence of the atherogenic metabolic triad identified patients at high risk of CAD even in the heart transplant population.     

奥利司他对肥胖青少年体重和机体组分的影响——随机对照试验

背景：儿童和青少年超重和肥胖正迅速增加。在该人群，单纯行为疗法减肥及维持体重下降的效果有限，但是对药物治疗尚未进行广泛的研究。 目的：确定奥利州他（Orlistat）在青少年体重治疗方面的效果及其安个性。 设计、地点和病例：于美国和加拿大32个中心、539例肥胖青少年（12—16岁；体重指数[body mass index，BMI]在第95百分化之上≥2单位）进行的多ln0、54剧（2000年8月至2002年10月）随机双盲研究。 干预：给予奥利司他（n=357）或安慰剂（n=182）120mg，每口3次，持续1年；加适度低热卡饮食（脂肪占30％）、运动和行为治疗。 主要观察指标：BMI变化；二级指标包括腰围和髋用、体重下降、脂质测量以及机体对口服葡萄糖的血糖和胰岛素反心。 结果：至12周时，两组BMI均有下降；此后，奥利司他组体重维持稳定而安慰剂组则超过基线。研究结束时，奥利司他组BMI下降0．55。而安慰剂组则增加0．31（P=0．001）。与安慰剂组的15．7％相比，奥利司他组26．5％的病例BMI下降≥5％（P=0．005）；BMI下降≥10％者分别为4．5％和13．3％（P=0．002）。在研究结束时，奥利司他组体重增加0．53kg，安慰剂组增加3．14kg（P〈0．001）。双能X线吸收测量娃示，这种差异可用脂肪体再的变化解释。奥利司他组腰围下降，安慰剂组腰围上升（-1．33cm比＋0．12cm；P〈0．05）。奥利司他组发生轻至中度胃肠道不良事件者为9％-50％，安慰剂组为1％～13％。 结论：与安慰剂比较，奥利司他与饮食、运动和行为改善联合可显著改善肥胖青少年体重的治疗。在这个青少年人群，连续使用奥利司他1年并无重要安全问题，尽管奥利司他组胃肠道不良事件较为常见。