Effects of glucose homeostasis on protein metabolism in patients with advanced chronic kidney disease.

Insulin deficiency is known to be associated with a state of increased muscle protein breakdown; this process is mediated by the ubiquitin-proteasome pathway. Convincing in vitro data are further supported by extensive studies in humans with insulin deprivation and are further substantiated by reversal of muscle protein breakdown with insulin treatment. In patients with end-stage renal disease (ESRD) and diabetes mellitus (DM), muscle protein breakdown is enhanced in both acute and chronic conditions. Recent data also point to the potential protein catabolic effects of insulin resistance combined with insulin deficiency. Because ESRD is associated with a state of insulin resistance, uremic muscle wasting may also be mediated by this pathway.     

AMPK在妊娠期糖尿病发病机制中的作用

腺苷酸活化蛋白激酶是一种重要的蛋白激酶,主要作用是协调代谢和能量平衡.腺苷酸活化蛋白激酶被激活后,在增加骨骼肌对葡萄糖摄取、增强胰岛素敏感性、增加脂肪酸氧化以及调节基因转录等方面发挥重要作用.已经证实脂联素有调节糖脂代谢的作用,但其作用机制尚不十分清楚,很可能是通过腺苷酸活化蛋白激酶介导,对脂联素信号转导通路的研究将成为进一步理解脂联素作用的关键所在.而脂联素又是妊娠期糖尿病的预测因子,所以腺苷酸活化蛋白激酶逐渐成为对妊娠期糖尿病研究中的焦点.     

Physical activity patterns in chronic hemodialysis patients: comparison of dialysis and nondialysis days.

OBJECTIVE: To determine physical activity patterns in chronic hemodialysis patients with a specific emphasis on the difference between dialysis and nondialysis days. Design A cross-sectional single-center study. SETTING: Vanderbilt University Outpatient Dialysis Unit. PATIENTS: Twenty current chronic hemodialysis patients: 10 male, 10 female; 15 black, 5 white; mean age, 50.1 +/- 9.9 years; height, 164.5 +/- 10.9 cm; weight, 82.5 +/- 15.4 kg; length on dialysis, 57.3 +/- 45.3 months. METHODS: Minute-by-minute physical activity was assessed over a 7-day period using a triaxial accelerometer, which consists of raw numbers or counts calculated by the 3 axes of the accelerometer (PA counts). PA counts were extrapolated on a daily and hourly basis. Physical functioning tests included: sit-to-stand, 6-minute walk, and 1-repetition maximal leg press exercise. Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and cholesterol were also collected. MAIN OUTCOME MEASURE: PA counts. RESULTS: Total PA counts were significantly lower on dialysis days when compared with nondialysis days (128,279 +/- 74,009 versus 168,744 +/- 95,168, respectively, P = .025). The average PA counts during the 4-hour dialysis time period were significantly lower on dialysis days when compared with nondialysis days (3,086 +/- 3,749 versus 11,070 +/- 7,695, respectively, P = .001). At postdialysis hours 1 and 2, PA counts on dialysis days were significantly higher than on nondialysis days (11,410 +/- 5,340 versus 9,082 +/- 6,646, P = .008, and 14,048 +/- 9,728 versus 8,662 +/- 6,433, P = .016, respectively). By postdialysis hour 4, PA counts on dialysis days had significantly decreased when compared with nondialysis days (6,068 +/- 6,268 versus 10,512 +/- 7,420 PA counts, P = .01, respectively). From postdialysis hours 5 to 20, there was no significant difference in PA counts between dialysis and nondialysis days. CONCLUSION: This study shows that physical activity is lower on dialysis days when compared with nondialysis days, and this decrease is caused by the lack of activity during the 4-hour hemodialysis procedure. New behavior modification strategies involving physical activity, both during hemodialysis and on nondialysis days, must be examined in this patient population.     

臂丛神经根性损伤膈神经移位术对青壮年患者早期呼吸功能的影响

目的研究臂丛神经损伤膈神经移位术对青壮年患者早期呼吸功能的影响.方法对16例接受膈神经移位治疗的患者,在术前、术后（10 d）进行肺功能指标的比较,同时定期进行门诊随访,观察呼吸系统自觉症状程度.结果13例术后出现了不同程度的供氧不足症状,16例全部出现一侧膈肌抬高,术后第10天肺活量（VC）、肺活量预计值百分数（VC%）分别比术前减少37.98%和26.88%,两者差异有统计学意义（tvc=11.532、tvc%=0,P＜0.01）.其它项目如残气量（RV）较术前轻度下降,肺总量（TLC）下降值达到术前肺总量的36.49%,残气量/肺总量比值（RV/TLC%）较术前上升了4.75%,上述各指标的差值均有统计学意义.1 s用力呼气量/用力肺活量比值（FEV1/FVC）和术前比基本无改变,但其差值有统计学意义.膈神经移位右侧（10例）与左侧（6例）术前、术后肺活量比较差异有统计学意义.术后随访8个月～2年,所有患者均无明显呼吸困难和胸闷等症状.结论膈神经移位术后对青壮年患者肺容量有较大的丧失,肺通气功能减弱和小气道阻力增加,但其丧失程度在机体自身代偿耐受范围内,不会导致急剧发生的严重呼吸功能障碍.建议对右侧臂丛神经根性损伤的患者,术前进行严格的肺、心功能检查,避免发生较为严重的并发症.     

Body composition and physical activity in end-stage renal disease.

OBJECTIVE: The study objective was to examine the relationship between visceral and somatic protein stores and physical activity in individuals with end-stage renal disease. DESIGN: This was a prospective single-center study. SETTING: The study took place at the Vanderbilt University Outpatient Dialysis Unit and General Clinical Research Center. PATIENTS: Fifty-five patients with prevalent chronic hemodialysis (CHD) were included: 33 males, 22 females, 45 African Americans, 9 Caucasians, and 1 Asian. The mean age was 47.0 +/- 1.6 years, height was 166.4 +/- 13.9 cm, and weight was 83.1 +/- 2.6 kg. METHODS: Body composition was measured by dual-energy x-ray absorptiometry. Minute-by-minute physical activity was assessed over a 7-day period with a triaxial accelerometer. Participants were interviewed by a trained registered dietitian for two 24-hour diet recalls (one from a hemodialysis day; one from a nonhemodialysis day). Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and creatinine were also collected. MAIN OUTCOME MEASURE: Predictors of somatic protein stores were the main outcome measure. RESULTS: Serum albumin was negatively and significantly correlated with the percentage of fat mass (P = .016) and kg of fat mass (P = .044). C-reactive protein was positively and significantly correlated with body weight (P = .006), percentage of fat mass (P = .017), kg of fat mass (P = .006), and body mass index (P = .004). Physical activity and total daily protein intake were the strongest predictors of the amount of lean body mass (P = .01 and .003, respectively). CONCLUSION: The association between somatic protein and visceral protein stores is weak in patients with CHD. Whereas increased levels of physical activity and total daily protein intake are associated with higher lean body mass in patients with CHD, higher adiposity is associated with higher C-reactive protein and lower albumin values.     

An Analytic Model of Subminiature Auditory Sensation System for Sound Source Localization

It is reported that some types of insects have a remarkable ability to detect the direction of an incident sound even though its acoustic sensory organs are in very close proximity each other. Maybe the ears are jointed by a cuticular structure with which the separated motions can be coupled mechanically and thus be magnified. In this paper, a detailed model is setup to describe the principle of this type of localization using a mechanical coupled structure. The transfer functions and the responses of the model in terms of time and frequency are analyzed to describe the mechanism of its ability of directional hearing. This analytical model provides a method to design the experimental model for the predetermined incident sound pressure, and the analysis of this model shows that this structure have the ability to determine the direction of the incident stimulus.     

Diagnosis of gastric carcinoma by classification on feature projections

A new classification algorithm, called benefit maximizing classifier on feature projections (BCFP), is developed and applied to the problem of diagnosis of gastric carcinoma. The domain contains records of patients with known diagnosis through gastroscopy results. Given a training set of such records, the BCFP classifier learns how to differentiate a new case in the domain. BCFP represents a concept in the form of feature projections on each feature dimension separately. Classification in the BCFP algorithm is based on a voting among the individual predictions made on each feature. In the gastric carcinoma domain, a lesion can be an indicator of one of nine different levels of gastric carcinoma, from early to late stages. The benefit of correct classification of early levels is much more than that of late cases. Also, the costs of wrong classifications are not symmetric. In the training phase, the BCFP algorithm learns classification rules that maximize the benefit of classification. In the querying phase, using these rules, the BCFP algorithm tries to make a prediction maximizing the benefit. A genetic algorithm is applied to select the relevant features. The performance of the BCFP algorithm is evaluated in terms of accuracy and running time. The rules induced are verified by experts of the domain.