Electromyographic activity of the human lateral pterygoid muscle during contralateral and protrusive jaw movements

Understanding of the normal function of the lateral pterygoid muscle is limited. The principal aim here was to determine whether there is a progressive increase in lateral pterygoid activity as the mandibular condyle moves downwards and forwards as would be expected if the muscle is concerned with the precise horizontal positioning of the mandible. In eight humans, recordings were made of the activity of the superior (SHLP) and inferior (IHLP) heads of the lateral pterygoid and the masseter, anterior temporal, posterior temporal and digastric muscles, together with the movement of the palpated lateral condylar pole (JAWS-3D tracking system) during trials of a contralateral and a protrusive jaw movement. Recording sites in SHLP and, in one participant, IHLP were verified by computed tomography. In each participant there was a progressive increase in the rectified and smoothed SHLP and IHLP activity in association with condylar movement during the contralateral and protrusive jaw movement. Further, irregularities in condylar movement, which reflected variations in the rate at which the jaw was moved, were correlated in time with prominent bursts of SHLP and IHLP activity. In all participants there was a consistently high correlation coefficient between the rectified and smoothed SHLP and IHLP activity and condylar displacement during the contralateral or protrusive jaw movements. For example, the mean (+/-SD) correlation between anterior condylar translation during contralateral excursion and SHLP activity was 0.91+/-0.09, and for IHLP 0.96+/-0.02. For the masseter, anterior temporal, posterior temporal and digastric muscles, mean r-values were, respectively, 0.10+/-0.77; -0.14+/-0.72; 0.24+/-0.78; 0.54+/-0.47. When treated as a group the correlation coefficients for SHLP and IHLP were statistically significantly different from the correlation coefficients for the other muscles treated as a group (ANOVA; p < 0.002 for correlation with anterior translation). These observations support the notion that the lateral pterygoid provides the principal driving force for moving the jaw forwards or laterally in protrusive or lateral excursive condylar movements. Further, the data suggest that the muscle plays a part in the fine control of jaw movements.     

Inhaled activated protein C protects mice from ventilator-induced lung injury

Introduction  

Activated Protein C (APC), an endogenous anticoagulant, improves tissue microperfusion and endothelial cell survival in systemic inflammatory states such as sepsis, but intravenous administration may cause severe bleeding. We have thus addressed the role of APC delivered locally by inhalation in preventing acute lung injury from alveolar overdistention and the subsequent ventilator-induced lung injury (VILI). We also assessed the effects of APC on the activation status of Extracellular- Regulated Kinase 1/2 (ERK) pathway, which has been shown to be involved in regulating pulmonary responses to mechanical stretch.     

延边地区汉族和朝鲜族居民脂肪分布与代谢异常的关系

目的:了解延边地区朝鲜族和汉族居民的脂肪分布特征及其与血压、血脂及血糖的关系。方法:于2006-08-8/17在延边地区九龙和翁声社区随机选择40～60岁朝鲜族和汉族常住居民2378名进行内脏脂肪率和体脂肪率以及血压、血脂、血糖等生化指标的检测。调查以健康体检形式进行,①内脏脂肪和体脂肪率测定采用日本TANITA株式会社生产的BC-600型体成分计测定,并且按其判定标准确定超过标准者[内脏脂肪率≥15%(男)、≥10%(女),体脂肪率(40～59岁)≥23%(男)、≥36%(女),体脂肪率(≥60岁)≥25%(男)、≥37%(女)]。②取清晨空腹(禁食12h)静脉血,采用日立-7600-010全自动生化分析仪测量血清总胆固醇、三酰甘油、高密度脂蛋白胆固醇、空腹血糖等指标。③高血压的诊断标准:收缩压≥140mmHg(1mmHg=0.133kPa)及或舒张压≥90mmHg。④血脂异常的诊断标准:总胆固醇≥5.72mmol/L,三酰甘油≥1.7mmol/L,高密度脂蛋白胆固醇<0.90mmol/L(男)、<1.0mmol/L(女)。⑤高血糖的诊断标准:空腹血糖≥6.1mmol/L。结果:①汉族男性的内脏脂肪率和体脂肪率均值分别为(10.51±3.66)%和(22.70±4.85)%,朝鲜族男性分别为(9.16±3.81)%和(20.28±5.02)%,汉族均高于朝鲜族(P<0.01);汉族女性的内脏脂肪率和体脂肪率分别为(6.22±2.27)%和(35.31±5.65)%,朝鲜族女性分别为(5.88±2.19)%和(34.00±5.72)%,汉族均高于朝鲜族(P<0.01)。②汉族男性的内脏脂肪率和体脂肪率超标率分别为12.1%和45.8%,朝鲜族男性分别为7.8%和28.6%,汉族均高于朝鲜族(P<0.05);汉族女性的内脏脂肪率和体脂肪率超标率分别为6.7%和47.9%,朝鲜族女性分别为3.8%和37.3%,汉族均高于朝鲜族(P<0.05)。③Logistic逐步回归分析结果表明,内脏脂肪率与民族、性别、年龄、高血压、高三酰甘油血症和高血糖有密切关系;体脂肪率与民族、性别、高血压、高三酰甘油血症、低高密度脂蛋白血症和高血糖有密切的关系。结论:①延边地区汉族居民内脏脂肪率和体脂肪率平均水平及其超标率明显高于朝鲜族。②内脏脂肪率和体脂肪率均与民族、性别、年龄(体脂肪率除外)、高血压、高三酰甘油血症和高血糖相关。     

Kinetics of adipose tissue microdialysis-derived metabolites in critically ill septic patients: associations with sepsis severity and clinical outcome

Microdialysis (MD) provides the opportunity to monitor tissue metabolic changes. This study aimed to describe the kinetics of MD-derived metabolites during the course of critical sepsis, to assess whether these metabolites are useful in grading sepsis severity, and to investigate their prognostic use. To this end, 54 mechanically ventilated septic patients were prospectively studied, out of which 39 had shock. Upon sepsis onset, an MD catheter was inserted into the subcutaneous adipose tissue of the upper thigh. Dialysate samples were analyzed for glucose, pyruvate, lactate, and glycerol. Sampling was performed six times per day for a maximum of 6 days. The daily mean values of MD measurements were calculated for each patient. Arterial blood was analyzed for glucose, lactate, and glycerol concomitantly with dialysate sampling. Blood glucose and tissue glucose levels along with lactate levels were high during the entire study period. Tissue pyruvate and glycerol were also raised, whereas the lactate-pyruvate ratio was preserved. At study entry, patients with septic shock had higher tissue lactate (3.3 vs. 1.9 mmol/L, P = 0.01) and glycerol (340 vs. 169 μmol/L, P = 0.04) levels compared with those without shock. Nonsurvivors had higher tissue lactate (P = 0.008), glycerol (P = 0.004), and pyruvate (P = 0.002) levels than survivors during the whole observation period. Logistic regression analysis showed that age (odds ratio [OR], 1.075; 95% confidence interval [CI], 1.004-1.150; P = 0.03), Sequential Organ Failure Assessment score on day 1 (OR, 1.550; 95% CI, 1.043-2.312; P = 0.03), and tissue glycerol on day 1 (OR, 1.007; 95% CI, 1.001-1.012; P = 0.01) predicted mortality independently. In conclusion, critical sepsis is characterized by high tissue lactate and pyruvate levels and a preserved lactate-pyruvate ratio, suggesting a nonischemic mechanism for raised blood lactate levels. Septic shock is associated with higher tissue lactate and glycerol levels compared with sepsis without shock. Elevated tissue lactate, pyruvate, and glycerol levels are related to poor clinical outcome, with the latter constituting an independent predictor.     

Genetic factors affecting the consistency and magnitude of changes in plasma cholesterol in response to dietary challenge

We examined the role of common genetic variation in determining the consistency and magnitude of change in plasma total cholesterol (TC) levels in response to two separate changes from a high-saturated (SFA) to a low-saturated/high-polyunsaturated-fat (PUFA) diet, in a group of free-living healthy men and women. Consistent responders were defined as those whose mean difference in the change in TC was within one SD of the mean for all participants, and the remainder were defined as variable responders. DNA was obtained from 55 individuals and genotype determined at the apolipoprotein (apo) B locus (signal peptide, SP), apoCIII (C1100-T) and lipoprotein lipase (LPL) gene loci (HindIII). In the 38 consistent responders, the apoBSP24 allele was significantly more common than in the 17 individuals with a variable response (0.29 vs. 0.12; p < 0.05). No other polymorphism showed a significant frequency difference between groups. In the group as a whole, the correlation between the change in TC level in response to the first and second dietary change was 0.28 (p = 0.05), but those with one or more apoB SP24 alleles and those with the apoCIII genotype CC had a significantly higher correlation than those with other genotypes (0.46 (p = 0.05) vs. 0.12 (NS) and 0.31 (p = 0.05) vs. 0.02 (NS), respectively). In the group as a whole, mean response left TC 10% higher on the SFA than on the PUFA diet, and neither apoB nor apoCIII genotypes affected the magnitude of this response. However, individuals with the LPL HindIII genotype H+ H+ had a significantly smaller change in mean TC in response to diet than those with one or more H- allele (9.3% vs. 14.4%; p = 0.03). Thus variation at the apoB and apoCIII loci affects the consistency of response to change in dietary fat content, while variation at the LPL gene locus affects magnitude of response.      

Angiopoietin-2 is increased in severe sepsis: correlation with inflammatory mediators

OBJECTIVE: Angiopoietin (Ang)-2 is an endothelium-specific growth factor, regulated by proinflammatory stimuli, that destabilizes vascular endothelium and increases vascular leakage; consequently, Ang-2 may contribute to sepsis pathophysiology. We have studied 1) serum Ang-2 levels in critically-ill patients and investigated potential relationships with inflammatory mediators and indices of disease severity and 2) the effect of sepsis-related inflammatory mediators on Ang-2 production by lung endothelium in vitro. DESIGN: Prospective clinical study followed by cell culture studies. SETTING: General intensive care unit and research laboratory of a university hospital. SUBJECTS: Human and bovine lung microvascular endothelial cells and 61 patients (32 men). Patients were grouped according to their septic stage as having: no systemic inflammatory response syndrome (n = 6), systemic inflammatory response syndrome (n = 8), sepsis (n = 16), severe sepsis (n = 18), and septic shock (n = 13). INTERVENTIONS: Cells were exposed to lipopolysaccharide, tumor necrosis factor-alpha, and interleukin-6. MEASUREMENTS AND MAIN RESULTS: Patients' serum Ang-2 levels were significantly increased in severe sepsis as compared with patients with no systemic inflammatory response syndrome or sepsis (p < .05 by analysis of variance). Positive linear relationships were observed with: serum tumor necrosis factor-alpha (rs = 0.654, p < .001), serum interleukin-6 (rs = 0.464, p < .001), Acute Physiology and Chronic Health Evaluation II score (rs = 0.387, p < .001), and Sequential Organ Failure Assessment score (rs = 0.428, p < .001). Multiple regression analysis revealed that serum Ang-2 is mostly related to serum tumor necrosis factor-alpha and severe sepsis. Treatment of human lung microvascular endothelial cells with all mediators resulted in a concentration-dependent Ang-2 reduction. Treatment of bovine lung microvascular endothelial cells with lipopolysaccharide and tumor necrosis factor-alpha increased Ang-2 release, and interleukin-6 reduced basal Ang-2 levels. CONCLUSIONS: First, patients' serum Ang-2 levels are increased during severe sepsis and associated with disease severity. The strong relationship of serum Ang-2 with serum tumor necrosis factor-alpha suggests that the latter may participate in the regulation of Ang-2 production in sepsis. Second, inflammatory mediators reduce Ang-2 release from human lung microvascular endothelial cells, implying that this vascular bed may not be the source of increased Ang-2 in human sepsis.     

High prevalence of decreased cortisol reserve in brain-dead potential organ donors

OBJECTIVE: To investigate the adrenocortical function in brain-dead patients, potential organ donors. DESIGN: Prospective study. SETTING: Intensive care units in two teaching hospitals. PATIENTS: A total of 37 patients (28 men, nine women) with severe brain injury, having a mean age of 42 +/- 18 yrs, were included in the study. Group A consisted of 20 brain-injured patients who did not deteriorate to brain death. Group B included 17 brain-injured patients who were brain dead; of these, ten patients developed brain death during ICU stay and seven patients were admitted to the ICU after clinical brain death. INTERVENTIONS: In all patients (group A and group B), a morning blood sample was obtained at admission to the ICU to determine baseline plasma cortisol. Subsequently, 1 microg of corticotropin (adrenocorticotropic hormone, Synacthen) was administered intravenously, and a blood sample was taken 30 mins after the injection. In group B patients who became brain dead while being treated in the ICU (n = 10), the same procedure was repeated the morning after the confirmation of brain death. Patients having a cortisol level of at least 18 microg/dL after the administration of adrenocorticotropic hormone were defined as responders. MEASUREMENTS AND MAIN RESULTS: After the occurrence of brain death, group B patients had significantly lower values for baseline (8.5 +/- 6.2 vs. 17.0 +/- 6.6 microg/dL, p <.001) and stimulated (16.9 +/- 6.3 vs. 23.9 +/- 5.7 microg/dL, p =.001) plasma cortisol compared with group A patients. Thirteen group B patients (76%) and two group A patients (10%) were nonresponders to adrenocorticotropic hormone (p <.001). In group B patients, baseline and stimulated cortisol concentrations were significantly related (r =.71, p =.001), whereas there was no correlation between baseline cortisol and the increment in cortisol (r = -.37, p =.15). Mean hormonal data of the ten brain-dead patients studied at admission in the ICU and after the occurrence of brain death were the following: baseline plasma cortisol (23.5 +/- 11.4 vs. 6.8 +/- 4.2 microg/dL, p =.003) and stimulated serum cortisol (28.8 +/- 9.9 vs. 16.3 +/- 4.3 microg/dL, p =.008). CONCLUSIONS: Adrenal cortisol secretion after dynamic stimulation is deficient in a substantial proportion of brain-dead potential organ donors.