猕猴对不同极化方向微波辐射能量吸收的研究

为提供微波辐射安全标准必要的数据，研究了不同极化方向微波辐射能量对猕猴的影响。实验在医学微波无反射室中进行，分为电场，磁场和微波传输方向极化组，辐射频率１ＧＨｚ，用红外热图技术，对暴露在三种极化方向电磁场中猕猴面部各解剖特片部位及胸部在辐射前后进行温度变化的定量分析。     

Energy recommendations for normal weight,overweight and obese children and adolescents: are different equations necessary?

In 2002/2005, separate energy requirement equations were generated by the Institute of Medicine's (IOM) Dietary Reference Intake process for normal weight and overweight/obese children and adolescents. The current paper questions the theoretical rationale of having two sets of equations (based solely on body-weight classification): when body weight is considered, overweight and obese children and adolescents do not seem to differ from their normal weight counterparts in energy expended for basal metabolism or physical activity tasks. However, energy needs for weight maintenance among overweight/obese girls were consistently higher when predicted using the equations for overweight/obese individuals compared with those developed for normal weight individuals. In contrast, among overweight/obese boys, they were consistently lower . Although the differences are within the variability of the estimates, even theoretical support for a higher energy intake (as occurs in girls) seems unwise because of the potential contribution to a higher body mass in children who are already at risk. It is the opinion of the authors that the IOM revisit the use of two separate equations and generate one set that is appropriate for all children and adolescents.     

Comparison between a swim-up and a Percoll gradient technique for the separation of human spermatozoa

Two methods of separating human sperm were compared using twenty-two semen samples. The sperm were separated by a swim-up technique or by self-migration on a Percoll gradient followed by medium change. After separation, the sperm obtained were assessed for progressive motility, ATP content, energy charge index ([ATP + 0.5 ADP]/[ATP + ADP + AMP]) and morphology. In general, and especially for semen samples containing less than 20 X 10(6) sperm/ml, separation by Percoll gradient selected sperm that were superior to those separated by the swim-up technique. The relatively high energy charge index (greater than 0.8) showed that the sperm tolerated the separation conditions well. It is suggested that self-migration on a Percoll gradient should prove useful for obtaining sperm of high quality.     

The effect of seamustard on blood lipid profiles and glucose level of rats fed diet with different energy composition

Recently, Korean people are consuming seaweeds almost 3.5 times more now than three decades ago. It is well known that seaweeds contain lots of soluble dietary fiber in addition to micronutrients such as β-carotene, iodine and some bioactive components. Seaweeds are considered to be effective for preventing chronic diseases including obesity, diabetes mellitus, atherosclerosis, cancer or constipation. This study was conducted to investigate the effect of seamustard intake on body weight gain, blood glucose level and lipid profiles in rats fed diets with different energy nutrient composition. Male Sprague-Dawley rats (average initial weight 103.7 g) were divided into groups for two experiments as follows; Control, M2.5 & M5 groups (Exp. I) and M5, M10, HCM5, HCM10, HFM5 & HFM10 groups (Exp. II). The rats were fed diet and water ad libitum for 4 weeks. In general, there was no significant difference in blood glucose and triglyceride concentration among groups. In Exp. I, serum LDL-cholesterol level of rats fed diet with 5% seamustard powder (M5) was significantly lower than that of control group, while HDL-cholesterol level, TC/LDL ratio and weight of adrenal gland were higher. In Exp. II, food intake, body weight gain and EER of high fat diet with 10% seamustard group (HFM10) were the lowest among groups. Except gastrocnemius muscle, all organ weights of HFM10 group were the lowest. Fecal cholesterol excretion and serum LDL-cholesterol concentration of HFM10 group were the highest, while serum HDL-cholesterol level was the lowest among groups. Interestingly, HDL-cholesterol concentration was the highest in HCM5 group among groups. From these results, it was suggested that seamustard intake might be more effective for body weight control, but not for improving blood lipid profiles in high fat diet than in high carbohydrate diet.     

ITERATIVE DYNAMIC PROGRAMMING FOR MINIMUM ENERGY CONTROL PROBLEMS WITH TIME DELAY

This paper presents the use of iterative dynamic programming employing exact penalty functions for minimum energy control problems. We show that exact continuously non-differentiable penalty functions are superior to continuously differentiable penalty functions in terms of satisfying final state constraints. We also demonstrate that the choice of an appropriate penalty function factor depends on the relative size of the time delay with respect to the final time and on the expected value of the energy consumption. A quadratic approximation (QA) of the delayed variables is much better than a linear approximation (LA) of the same for relatively large time delays. The QA improves the rate of convergence and avoids the formation of ‘kinks‘. A more general way of selecting appropriate penalty function factors is given and the results obtained using four illustrative examples of varying complexity corroborate the efficacy of the method.     

Significance of the hepatic mitochondrial redox state in the development of posttraumatic jaundice

The effect of the hepatic energy status on the development of posttraumatic jaundice (PTJ) was studied to clarify the mechanism of PTJ. Fifty-four patients with severe torso injury who were expected to develop PTJ on admission with an average Injury Severity Score of 27 were selected for this study. They were retrospectively divided into three groups according to their maximum bilirubin concentration by day 10: group H, 12 patients with marked elevation of serum bilirubin (>8 g/dl); group L, 23 with mild bilirubinemia (2–8 g/dl); and group N, 19 with no bilirubinemia (<2 g/dl). Group H patients, in whom trauma-related shock was severe and prolonged, developed severe hyperbilirubinemia, and their arterial ketone body ratio (AKBR), which reflects the hepatic mitochondrial redox state and is closely correlated to its energy production, was significantly lower throughout the first week. In contrast, the AKBR increased to an above normal level, indicating enhanced energy production in groups N and L. The serum direct/total bilirubin was also higher in group H. The abnormal hepatic energy metabolism is considered to have reduced the excretion of conjugated bilirubin from the hepatocytes into the bile canaliculi, which is a process that has to proceed against the bilirubin concentration gradient. The subsequent diffusion of the accumulated water-soluble conjugated bilirubin in hepatocytes into the blood is thus considered to be one of the causes of PTJ.     

眼镜蛇人蛰前、蛰眠期和出蛰后血清激素与能量物质代谢的关系

本文研究眼镜蛇入蛰前、蛰眠期及出蛰后血清 T_3,T_4和皮质醇水平与体内能量物质的含量变化关系,探讨其与蛰眠行为的关系。结果表明入蛰前眼镜蛇大量摄食储能过冬,由于血清激素水平降低,控制了体内组织器官的氧化代谢系统,使新陈代谢逐渐下降。蛰眠期血糖血脂明显下降,耗氧量显著减少,呈节能低代谢状态。此期血清激素水平已升高,但低温抑制了体内代谢。出蛰后血清激素水平明显升高且在春暖升温季节使眼镜蛇代谢率升高。     

Daily nutrient intake represents a modifiable determinant of nutritional status in chronic haemodialysis patients.

BACKGROUND: In maintenance haemodialysis patients, daily food intake is changeable; however, its relationship with nutritional status is unexplored. This study aimed to evaluate the isolated, long-term effect of daily nutrient intake on nutritional status in haemodialysis patients. METHODS: We performed a prospective 1-year controlled study in 27 chronic haemodialysis patients, without recognized risk factors for malnutrition. Each day for 1 week, four times in the year, we measured protein nitrogen appearance, and assessed dietary protein (DPI) and energy (DEI) intake from dietary diaries. We compared the nutritional outcome of patients spontaneously reducing nutrient intake below the threshold of 0.8 g/kg body weight/day for DPI and 25 kcal/kg body weight/day for DEI during the week (LOW, n = 8), with controls at adequate nutrient intake (CON, n = 19). An interventional 6-month study was then carried out in LOW to verify the cause-effect relationship. RESULTS: All patients showed a day-by-day reduction of whole nutrient intake during interdialytic period, which was mostly relevant in the third interdialytic day (L3). During the 1-year study, even in the presence of adequate dialysis dose and normal inflammatory indexes, body weight (68.0 +/- 5.5 to 65.8 +/- 5.9 kg), serum albumin (3.96 +/- 0.07 to 3.66 +/- 0.06 g/dl) and creatinine (9.2 +/- 1.1 to 8.1 +/- 0.7 mg/dl) significantly decreased in LOW but not in CON. Diaries evidenced in LOW a reduced number of meals at L3 that was explained by the fear of excessive interdialytic weight gain. During the interventional study, daily DPI and DEI increased at L3; this was associated with a significant increment of body weight, and serum albumin and creatinine levels. CONCLUSIONS: In maintenance haemodialysis patients the persistent, marked reduction of daily nutrient intake, even if limited to a single day of the week, is an independent determinant of reversible impairment of nutritional status.     

Influence of stretch-shortening cycle on mechanical behaviour of triceps surae during hopping

Belli , A. & Bosco, A. 1992. Influence of stretch-shortening cycle on mechanical behaviour of triceps surae during hopping. Acta Physiol Scand 144 , 401408. Received 20 March 1 991 , accepted 3 December 1991. ISSN 0001–6772. Laboratories of Physiology, Universities of St Etienne and Lyon, France and Departments of Biology and Physical Activity, University of Jyväskylä, Finland. Six subjects performed a first series of vertical plantar flexions and a second series of vertical rebounds, both involving muscle triceps surae exclusively. Vertical displacements, vertical forces and ankle angles were recorded during the entire work period of 60 seconds per series. In addition, expired gases were collected during the test and recovery for determination of the energy expenditure. Triceps surae was mechanically modelled with a contractile component and with an elastic component. Mechanical behaviour and work of the different muscle components were determined in both series. The net muscular efficiency calculated from the work performed by the centre of gravity was 17.5±3.0% (mean ± SD) in plantar flexions and 29.9 ± 4.8% in vertical rebounds. The net muscle efficiency calculated from the work performed by the contractile component was 17.4 %% 2.9% in plantar flexions and 16.1 ± 1.47; in vertical rebounds. These results suggest that the muscular efficiency differences do not reflect muscle contractile component efficiency but essentially the storage and recoil of elastic energy. This is supported by the relationship (P < 0.01) found in vertical rebounds between the extra work and the elastic component work. A detailed observation of the mechanical behaviour of muscle mechanical components showed that the strategy to maximize the elastic work depends also on the force-velocity characteristics of the movement and that the eccentric-concentric work of the contractile component does not always correspond respectively to the ankle extension-flexion.     

Prevention of ischemia-reperfusion injury by metabolic substrate—Mechanisms and surgical implications

Summary Background Despite new insights into mechanisms contributing to ischemia-reperfusion injury, new therapeutic interventions to reduce ischemia-reperfusion injury have thus far not been available for routine clinical use. In order to restore sufficient postischemic contractile function, such a therapy would be of great value in conjunction with reperfusion therapy for acute myocardial infarction and after cardiac surgery. This paper examines whether metabolic disturbances and energy depletion contribute to ischemia-reperfusion injury and whether metabolic interventions could alleviate ischemia-reperfusion injury. Methods Experimental and clinical studies are reviewed for evidence of a beneficial effect of metabolic interventions, in particular of increased glycolytic substrate, on ischemia-reperfusion injury. Results During ischemia, metabolism of the myocardium shifts to a preferential use of carbohydrates. Increased glycolytic substrate i.e. glucose-insulin-potassium infusion as metabolic support for ischemic myocardium is beneficial in reducing ischemia-reperfusion injury by increasing energy production via anaerobic glycolysis, decreasing circulating free fatty acids and intracellular free fatty acid accumulation, maintaining ion homeostasis, reducing cellular edema, and scavenging free radicals. During reperfusion, glucose-insulin-potassium, apart from increasing glycolysis and decreasing free fatty acid metabolism, provides substrate for replenishment of the citric acid cycle, which is important for optimal energy transfer. Conclusions During ischemia, glucose-insulin-potassium preserves energy reserves and maintains cell viability. During reperfusion, glucose-insulin-potassium improves energy transfer and increases contractile function. Experimental and clinical studies have proven glucose-insulin-potassium to be a safe and effective intervention to reduce ischemia-reperfusion injury.