Changes of Respiratory Chain Activity in Mitochondrial and Synaptosomal Fractions Isolated from the Gerbil Brain After Graded Ischaemia

Abstract: In this study we have examined (1) the integrated function of the mitochondrial respiratory chain by polarographic measurements and (2) the activities of the respiratory chain complexes I, II–III, and IV as well as the ATP synthase (complex V) in free mitochondria and synaptosomes isolated from gerbil brain, after a 30-min period of graded cerebral ischaemia. These data have been correlated with cerebral blood flow (CBF) values as measured by the hydrogen clearance technique. Integrated functioning of the mitochondrial respiratory chain, using both NAD-linked and FAD-linked substrates, was initially affected at CBF values of ∼35 ml 100 g⁻¹ min⁻¹, and declined further as the CBF was reduced. The individual mitochondrial respiratory chain complexes, however, showed differences in sensitivity to graded cerebral ischaemia. Complex I activities decreased sharply at blood flows below ∼30 ml 100 g⁻¹ min⁻¹ (mitochondria and synaptosomes) and complex II–III activities decreased at blood flows below 20 ml 100 g⁻¹ min⁻¹ (mitochondria) and 35–30 ml 100 g⁻¹ min⁻¹ (synaptosomes). Activities declined further as CBF was reduced below these levels. Complex V activity was significantly affected only when the blood flow was reduced below 15–10 ml 100 g⁻¹ min⁻¹ (mitochondria and synaptosomes). In contrast, complex IV activity was unaffected by graded cerebral ischaemia, even at very low CBF levels.     

Age-Related Ischemia in the Brain Following Bilateral Carotid Artery Occlusion—Collateral Blood Flow and Brain Metabolism

Cerebral blood flow (CBF) and cerebellar blood flow (CeBF) were measured and correlated with brain lactate, pyruvate and adenosine triphosphate concentrations from groups representing 3-week old suckling (n = 10), 18–22-week old adult (n = 9) and 70-week old aged (n = 7) Sprague-Dawley rats before and during bilateral carotid occlusion (BCO). The steal ratio, calculated as the ratio of %control CBF to %control CeBF, was 1.02 ± 0.06 (mean ± SEM) at 60 minutes of BCO in adult rats that exhibited normal levels of brain metabolites. By contrast, the ratios significantly decreased to 0.74 ± 0.06 in suckling rats and 0.69 ± 0.06 in aged rats with simultaneous increases by 2.4 to 2.9-fold of tissue lactate. Pyruvate and lactate/pyruvate ratio also increased by 1.4 to 1.8 times control in both suckling and aged rats. We conclude that there is age-related steal phenomenon occurring with blood flow during BCO. Ischemic derangement of the brain metabolism is in part related to poor blood supply from the posterior circulation in suckling and aged rats.     

Metabolic rates,genetic constraints,and the evolution of endothermy

The metabolic distinction between endotherms and ectotherms is profound. Whereas the ecology of metabolic rates is well studied, how endotherms evolved from their ectothermic ancestors remains unclear. The aerobic capacity model postulates that a genetic constraint between resting and maximal metabolism was essential for the evolution of endothermy. Using the multivariate breeders’ equation, I illustrate how the (i) relative sizes of genetic variances and (ii) relative magnitudes of selection gradients for resting and maximal metabolism affect the genetic correlation needed for endothermy to have evolved via a correlated response to selection. If genetic variances in existing populations are representative of ancestral conditions, then the aerobic capacity model is viable even if the genetic correlation was modest. The analyses reveal how contemporary data on selection and genetic architecture can be used to test hypotheses about the evolution of endothermy, and they show the benefits of explicitly linking physiology and quantitative genetic theory.     

Creatine Kinase Activity in Postnatal Rat Brain Development and in Cultured Neurons, Astrocytes, and Oligodendrocytes

The development and distribution of cytosolic creatine kinase (CK) activity was studied in rat brain and in cell culture. The activity of CK in whole brain increased almost fivefold during the period from birth to day 40 when adult levels of 18-19 U/mg of protein were attained. The distribution of CK activity was examined in dissected regions of the adult brain and was nonuniform; the cerebellum, the striatum, and the pyramidal tracts contained significantly higher CK activity than did whole brain. The cellular compartmentation of CK was investigated using primary cultures of purified neurons, astrocytes, and oligodendrocytes. The CK activity in neurons increased fourfold greater than that measured at the time of isolation to 4 U/mg of protein. The CK activity in astrocytes cultured for 20 days was 3.5 U/mg of protein and was 1.5-fold greater than that measured at the time of isolation. In contrast, the CK activity in cultured oligodendrocytes (day 20) was three- to fourfold higher than that determined in astrocytes and almost sevenfold higher than the activity measured at the time the cells were isolated. The high levels of CK in cultured oligodendrocytes suggest a role for this enzyme in oligodendrocyte function and/or myelinogenesis.     

Metabolic Changes in Cerebral Cortex, Hippocampus, and Cerebellum During Sustained Bicuculline-Induced Seizures

Abstract— The objective of the present experiments was to study metabolic correlates to the localization of neuronal lesions during sustained seizures. To that end, status epilepticus was induced by i.v. administration of bicuculline in immobilized and artificially ventilated rats, since this model is known to cause neuronal cell damage in cerebral cortex and hippocampus but not in the cerebellum. After 20 or 120 min of continuous seizure activity, brain tissue was frozen in situ through the skull bone, and samples of cerebral cortex, hippocampus, and cerebellum were collected for analysis of glycolytic metabolites, phosphocreatine (PCr), ATP, ADP, AMP, and cyclic nucleotides. After 20 min of seizure activity, the two “vulnerable” structures (cerebral cortex and hippocampus) and the “resistant” one (cerebellum) showed similar changes in cerebral metabolic state, characterized by decreased tissue concentrations of PCr, ATP, and glycogen, and increased lactate concentrations and lactate/ pyruvate ratios. In all structures, though, the adenylate energy charge remained close to control. At the end of a 2-h period of status epilepticus, a clear deterioration of the energy state was observed in the cerebral cortex and the hippocampus, but not in the cerebellum. The reduction in adenylate energy charge in the cortex and hippocampus was associated with a seemingly paradoxical decrease in tissue lactate levels and with failure of glycogen resynthesis (cerebral cortex). Experiments with infusion of glucose during the second hour of a 2-h period of status epilepticus verified that the deterioration of tissue energy state was partly due to reduced substrate supply; however, even in animals with adequate tissue glucose concentrations, the energy charge of the two structures was significantly lowered. The cyclic nucleotides (cAMP and cGMP) behaved differently. Thus, whereas cAMP concentrations were either close to control (hippocampus and cerebellum) or moderately increased (cerebral cortex), the cGMP concentrations remained markedly elevated throughout the seizure period, the largest change being observed in the cerebellum. It is concluded that although the localization of neuronal damage and perturbation of cerebral energy state seem to correlate, the results cannot be taken as. evidence that cellular energy failure is the cause of the damage. Thus, it appears equally probable that the pathologically enhanced neuronal activity (and metabolic rate) underlies both the cell damage and the perturbed metabolic state. The observed changes in cyclic nucleotides do not appear to bear a causal relationship to the mechanisms of damage.     

Relationship Between Regional Brain Angiotensinogen a Local Blood Flow and Volume in the Adrenalectomize Rat: Application of Approach to Quantification of Brain Corticosterone Receptors

Abstract: Prior studies from this laboratory have established that angiotensinogen, the prohormone of angiotensin, is unevenly distributed in the rat brain and that adrenalectomy selectively perturbs levels of the prohormone in regions associated with cardiovascular neural pathways. However, plasma angiotensinogen levies are 10²-10³ times higher in plasma than in brain, so that the observation of a unique distribution of brain angiotensinogen may reflect variable plasma contamination. Studies were therefore undertaken to establish whether adrenalectomy selectively alters regional blood flow, blood volume, or plasma contamination of brain tissue, thereby artifactitiously altering apparent angiotensinogen levels. Radioactive 2-deoxyglucose, iodoantipyrine, and inulin were employed in these analyses. We conclude that variations in blood flow do not explain the selective effects of adrenalectomy, but that a variable extent of residual plasma contamination (remaining after transcardiac perfusion) is partially reflected in our earlier data. However, after correcting for plasma contamination, we still find significant changes in selected areas of the rat brain following adrenalectomy. Finally, our results demonstrate the necessity for direct quantitation of plasma contamination of brain tissue segments. This is shown to have relevance in other situations, such as corticosterone binding globulin contamination of brain corticosterone receptor binding.     

Comparison of hibernation, estivation and daily torpor in the edible dormouse, Glis glis

Three major forms of dormancy in mammals have been classified: hibernation in endotherms is characterised by reduced metabolic rate (MR) and body temperature (T _b) near ambient temperature (T _a) over prolonged times in the winter. Estivation is a similar form of dormancy in a dry and hot environment during summertime. Daily torpor is defined as reduced MR and T _b lower than 32 °C, limited to a duration of less than 24 h. The edible dormouse (Glis glis) is capable for all three distinct forms of dormancy. During periods of food restriction and/or low T _a, daily torpor is displayed throughout the year, alternating with hibernation and estivation in winter and summer respectively. We recorded T _b, O₂-consumption and CO₂-production in unrestrained dormice at different T _a's for periods of up to several months. Cooling rate and rate of metabolic depression during entrance into the torpid state was identical in all three forms of dormancy. The same was true for thermal conductance, maximum heat production, duration of arousal and cost of an arousal. The only difference between hibernation and daily torpor was found in the bout duration. A daily torpor bout lasted 3–21 h, a hibernation bout 39–768 h. As a consequence of prolonged duration, MR, T _b and also the T _b − T _a gradient decreased to lower values during hibernation bouts when compared to daily torpor bouts. Our findings suggest that all three forms of dormancy are based on the same physiological mechanism of thermal and metabolic regulation. Accepted: 27 June 2000     

Studies on the Linkage of Energy Metabolism and Neuronal Activity in the Isolated Perfused Rat Brain

An isolated rat brain preparation was perfused using glucose-free (=aglycemic) media. The high-energy phosphates, substrates of the glycolytic pathway, free atnino acids, acetylcholine as well as the intracellular distribution of hexokinase activity were determined in brain tissues. The EEG was evaluated visually. The levels of glycolytic substrates, glutamate, and glutamine in cortical tissue decreased after aglycemic perfusion, whereas the aspartate level increased and the GABA level remained unchanged. The high-energy phosphate content seemed to be unaffected for about 15 min of aglycemic perfusion and fell significantly after 20 min. The EEG of the isolated brain changed rapidly after starting aglycemic perfusion and became isoelectric after 12–15 min. Hyperglycemic perfusion (35 mmol glucose per liter perfusion medium) did not alter the energy metabolism of the isolated brain. The breakdown of cerebral energy metabolism and of EEG activity was postponed when thiopental was added to the perfusion medium. The soluble hexokinase activity measured in cortical tissue was reduced after aglycemic perfusion and was enhanced after thiopental. Hyperglycemic perfusion did not influence the intracellular hexokinase distribution. The acetylcholine level in the striatum of the isolated rat brain was significantly decreased by aglycemia and was increased in hypothalamus by thiopental. It was suggested that hexokinase bound to the mitochondrial membrane may play an important role in the relationship of energy metabolism and neuronal activity.     

The thermodynamics of thinking: connections between neural activity,energy metabolism and blood flow

Several current functional neuroimaging methods are sensitive to cerebral metabolism and cerebral blood flow (CBF) rather than the underlying neural activity itself. Empirically, the connections between metabolism, flow and neural activity are complex and somewhat counterintuitive: CBF and glycolysis increase more than seems to be needed to provide oxygen and pyruvate for oxidative metabolism, and the oxygen extraction fraction is relatively low in the brain and decreases when oxygen metabolism increases. This work lays a foundation for the idea that this unexpected pattern of physiological changes is consistent with basic thermodynamic considerations related to metabolism. In the context of this thermodynamic framework, the apparent mismatches in metabolic rates and CBF are related to preserving the entropy change of oxidative metabolism, specifically the O₂/CO₂ ratio in the mitochondria. However, the mechanism supporting this CBF response is likely not owing to feedback from a hypothetical O₂ sensor in tissue, but rather is consistent with feed-forward control by signals from both excitatory and inhibitory neural activity. Quantitative predictions of the thermodynamic framework, based on models of O₂ and CO₂ transport and possible neural drivers of CBF control, are in good agreement with a wide range of experimental data, including responses to neural activation, hypercapnia, hypoxia and high-altitude acclimatization.This article is part of the theme issue ‘Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity’.     

Hepatic and renal cadmium accumulation is associated with mass-specific daily metabolic rate in the bank vole (Clethrionomys glareolus)

Previous study has shown that photoperiod and age affect tissue accumulation of cadmium (Cd) in a small rodent, the bank vole. Since the body mass is also influenced by these factors, the present study was designed to determine whether mass-specific daily metabolic rate might be responsible for differential accumulation of Cd in the liver and kidneys of the short- and long-photoperiod bank voles as well as of the young and old animals. One- and five-month old male bank voles were held under short (8 h light/16 h dark) or long (16 h light/8 h dark) photoperiods and exposed to dietary Cd (100 microg/g) for 6 weeks. The bank voles raised under the short photoperiod and those injected subcutaneously with melatonin (7 micromol/kg/day) under the long photoperiod showed significantly higher concentrations of Cd in the liver (43-60%) and kidneys (40-47%) than the age-matched long-photoperiod animals. The old bank voles accumulated significantly less Cd in both organs than the young animals. These differences in Cd accumulation appeared not to be associated with the relative Cd intake. However, the hepatic and renal Cd levels followed a pattern similar to that of the mass-specific daily metabolic rate (or energy expenditure) and energy assimilation efficiency. These data indicate that mass-specific daily metabolic rate and energy assimilation efficiency (an indicative of digestive and absorptive processes) may be responsible for differential tissue Cd accumulation in the bank vole.     

Nicotinamide Attenuates Focal Ischemic Brain Injury in Rats: With Special Reference to Changes in Nicotinamide and NAD+ Levels in Ischemic Core and Penumbra

We investigated the neuroprotective action of nicotinamide in focal ischemia. Male spontaneously hypertensive rats (5–7 months old) were subjected to photothrombotic occlusion of the right distal middle cerebral artery (MCA). Either nicotinamide (125 or 250 mg/kg) or vehicle was injected IV before MCA occlusion. Changes in the cerebral blood flow (CBF) were monitored using laser-Doppler flowmetry, and infarct volumes were determined with TTC staining 3 days after MCA occlusion. In another set of experiments, the brain nicotinamide and nicotinamide adenine dinucleotide (NAD⁺) levels were analyzed by HPLC using the frozen samples dissected from the regions corresponding to the ischemic core and penumbra. In the 250-mg/kg nicotinamide group, the ischemic CBF was significantly increased compared to that the untreated group, and the infarct volumes were substantially attenuated (–36%). On the other hand, the ischemic CBF in the 125 mg/kg nicotinamide group was not significantly different from the untreated CBF, however, the infarct volumes were substantially attenuated (–38%). Cerebral ischemia per se did not affect the concentrations of nicotinamide and NAD⁺ both in the penumbra and ischemic core. In the nicotinamide groups, the brain nicotinamide levels increased significantly in all areas examined, and brain NAD⁺ levels increased in the penumbra but not in the ischemic core. Increased brain levels of nicotinamide are considered to be primarily important for neuroprotection against ischemia, and the protective action may be partly mediated through the increased NAD⁺ in the penumbra.     

内蒙古浑善达克沙地小毛足鼠的能量代谢和体温调节

为了解小毛足鼠对沙漠生境的适应特征,对其能量代谢和体温调节特征进行了测定。代谢率采用封闭式流体压力呼吸计测定,非颤抖性产热用皮下注射去甲肾上腺素诱导,能量摄入采用食物平衡法测定。结果显示:小毛足鼠的热中性区为25～33℃,平均体温为35 7±0 1℃,最小热传导率为0 21±0 01mlO2/g·h·℃,基础代谢率为2 61±0 04mlO2/g·h,最大非颤抖性产热为8 53±0 28mlO2/g·h,非颤抖性产热范围(最大非颤抖性产热与基础代谢率的比率)为3 3。基础代谢率和非颤抖性产热都高于以体重为基础的期望值,最小热传导接近期望值。小毛足鼠的摄入能为2 26±0 12kJ/g·d;消化能为2 18±0 13kJ/g·d;消化率为97±0 2%;可代谢能为2 13±0 12kJ/g·d;可代谢能效率为94±1 2%。这些结果表明小毛足鼠对沙地生境的适应特征是:基础代谢率较高,体温相对较低,最小热传导率与期望值相当,热中性区较宽,下临界温度较低;较高的最大非颤抖性产热和非颤抖性产热范围以及较高的食物消化效率。     

目标导向液体治疗联合右美托咪定对创伤性颅脑损伤患者血流动力学、脑氧代谢及炎症因子的影响

目的:探讨目标导向液体(GDFT)治疗联合右美托咪定对创伤性颅脑损伤(TBI)患者血流动力学、脑氧代谢及炎症因子的影响。方法:选取2016年3月~2019年3月期间我院收治的TBI患者142例,根据随机数字表法分为对照组1(n=47,GDFT治疗)、对照组2(n=47,常规液体联合右美托咪定)和研究组(n=48,GDFT联合右美托咪定),比较三组患者围术期指标、血流动力学、脑氧代谢及炎症因子变化情况,记录三组围术期间不良反应状况。结果:三组患者术后12、24 h心率(HR)、呼吸频率(RR)及动脉-颈内静脉血氧含量差(AVDO2)均较术前降低,且研究组低于对照组1、对照组2(P<0.05);三组患者术后12、24 h血氧饱和度(Sjv O2)较术前升高,且研究组高于对照组1、对照组2(P<0.05);三组患者术后12、24 h白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)呈逐渐下降趋势(P<0.05);研究组术后12、24 h的IL-6、TNF-α低于对照组1、对照组2(P<0.05)。对照组2、对照组1、研究组术中总液体量、胶体量、晶体量依次减少(P<0.05),住院天数依次缩短(P<0.05)。三组不良反应发生率对比未见显著差异(P>0.05)。结论:TBI患者手术麻醉过程中给予GDFT联合右美托咪定方案,促进机体HR、RR趋于平稳的同时还可改善脑氧代谢及炎性因子水平,且不增加不良反应发生率。     

Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs

The cross-sectional area of a nutrient foramen of a long bone is related to blood flow requirements of the internal bone cells that are essential for dynamic bone remodelling. Foramen area increases with body size in parallel among living mammals and non-varanid reptiles, but is significantly larger in mammals. An index of blood flow rate through the foramina is about 10 times higher in mammals than in reptiles, and even higher if differences in blood pressure are considered. The scaling of foramen size correlates well with maximum whole-body metabolic rate during exercise in mammals and reptiles, but less well with resting metabolic rate. This relates to the role of blood flow associated with bone remodelling during and following activity. Mammals and varanid lizards have much higher aerobic metabolic rates and exercise-induced bone remodelling than non-varanid reptiles. Foramen areas of 10 species of dinosaur from five taxonomic groups are generally larger than from mammals, indicating a routinely highly active and aerobic lifestyle. The simple measurement holds possibilities offers the possibility of assessing other groups of extinct and living vertebrates in relation to body size, behaviour and habitat.     

Structural and Metabolic Relationships Between Goldfish Brain Glycoproteins Participating in Functional Plasticity of the Central Nervous System

Ependymins beta and gamma (MW 32,000 and 26,000 daltons) are two secreted goldfish brain glycoproteins that exhibit a specifically enhanced turnover rate when the animals successfully acquire a new pattern of swimming behaviour. Both proteins are bound identically to concanavalin A and can be isolated from brain extracellular fluid and from brain cytoplasm by lectin affinity chromatography. Radioimmunoassay data, using purified 125I-labeled ependymins and antisera directed against ependymin beta or ependymin gamma, show complete cross-reactivity between the two proteins. It is demonstrated by Scatchard-plot analysis that the antisera recognize identical immunological determinants in both proteins. The amino acid composition of the ependymins is similar, and several identical polypeptide fragments are obtained after limited proteolysis with Staphylococcus aureus protease. The proteins are capable of forming complexes of the compositions gamma 2, beta gamma, and beta 2. A protease present in the extracellular fluid of goldfish brain promotes proteolysis of ependymin beta to ependymin gamma. The finding that ependymin gamma is physiologically derived from ependymin beta suggests the possibility that ependymin beta might exert its biological function during consolidation of new behavioural patterns via smaller polypeptide fragments.     

功能性电刺激联合循环运动系统对老年脑卒中后肌肉衰减综合征患者肢体功能、平衡能力以及认知功能的影响

摘要 目的：研究功能性电刺激联合循环运动系统对老年脑卒中后肌肉衰减综合征患者肢体功能、平衡能力以及认知功能的影响。方法：选择2020年6月到2021年6月在我院进行康复治疗的老年脑卒中后肌肉衰减综合征患者64例,据其治疗方式的不同分为对照组和研究组,两组患者均给予常规康复治疗,对照组患者在常规治疗的基础上加用功能性电刺激治疗,而研究组在对照组基础上加用脑循环系统治疗仪进行治疗,比较两组患者临床治疗疗效。使用运动功能评分法（FMA）和上肢功能评定（STEF）评价肢体患者功能,使用平衡量表（BBS）和Fuglg-Meyer平衡量表（FM-B）评价患者平衡能力,使用自拟认知量表评价患者认知功能。结果：（1）研究组患者临床治疗总有效率较对照组高（93.75 % vs 75.00 %,P<0.05）;（2）两组患者治疗后FMA和STEF评分均显著增高（P<0.05）,并且研究组患者治疗后BBS和FM-B评分显著高于对照组患者（P<0.05）;（3）两组患者治疗后BBS和FM-B评分均显著增高,并且研究组患者治疗后BBS和FM-B评分显著高于对照组患者（P<0.05）;（4）两组患者治疗后认知功能评分均升高,并且研究组患者较对照组患者高（P<0.05）。结论：功能性电刺激联合循环运动系统对老年脑卒中后肌肉衰减综合征患者具有显著的临床治疗效果,可显著改善患者肢体功能、平衡能力和认知功能。     

核心稳定性训练联合高压氧对脑梗死恢复期患者血液流变学、脑能量代谢和血清NGF、NSE、MBP的影响

摘要 目的：观察核心稳定性训练联合高压氧对脑梗死恢复期患者血液流变学、脑能量代谢和血清神经生长因子（NGF）、神经元特异性烯醇化酶（NSE）、髓鞘碱性蛋白（MBP）的影响。方法：选择我院2018年3月~2021年3月期间收治的脑梗死恢复期患者103例。采用随机数字表法将患者分为对照组和观察组两组,例数分别为51例和52例。对照组患者接受核心稳定性训练,观察组患者接受核心稳定性训练联合高压氧治疗,对比两组疗效、血液流变学、脑能量代谢指标和血清NGF、NSE、MBP水平及相关量表评分。结果：观察组的临床总有效率高于对照组（P<0.05）。治疗后,两组上肢/下肢Lovett肌力评分升高,美国国立卫生研究院卒中量表（NIHSS）评分下降,且观察组的改变程度大于对照组（P<0.05）。治疗后,两组全血高切黏度、血细胞比容、全血低切黏度、血浆黏度下降,且观察组的改变程度大于对照组（P<0.05）。治疗后,两组血氧饱和度升高,空腹血糖、乳酸水平下降,且观察组的改变程度大于对照组（P<0.05）。治疗后,两组NGF水平升高,NSE、MBP水平下降,且观察组的改变程度大于对照组（P<0.05）。结论：核心稳定性训练联合高压氧应用于脑梗死恢复期患者,可促进其血液流变学、脑能量代谢改善,有效调节血清NGF、NSE、MBP水平,疗效明确。     

代谢综合征患者肥胖和脂质代谢参数的特征及其诊断价值

目的:比较代谢综合征(MetS)患者不同肥胖和脂质代谢参数的特征和其对疾病的诊断价值。方法:回顾性分析2016年1月至2018年12月在我院就诊的MetS患者和健康体检者,比较其体重指数(Body Mass Index, BMI)、腰高比(Waist-to-Height Ratio,WHt R)、甘油三酯/高密度脂蛋白胆固醇(TG/HDL-C)、脂肪蓄积指数(Lipid accumulation product, LAP)和内脏脂肪指数(Visceral adiposity index,VAI)的差异及不同代谢因素分组患者上述参数差异。采用ROC曲线评价不同肥胖和脂质代谢参数对MetS的诊断价值。结果:与健康组相比,MetS组无论男性还是女性患者BMI、WC、WHt R、血压、FPG、TG、TG/HDL-C、LAP和VAI均明显升高,而HDL-C显著降低(P0.05)。随着MetS特征个数的增加,MetS组患者的BMI、WHt R、TG/HDL-C、LAP和VAI均呈现显著增加趋势(P0.05)。上述五个诊断MetS的ROC曲线中都是LAP的AUC最大,男性AUC为0.896,敏感度为0.75,特异度为0.84。女性LAP的AUC为0.874,最佳诊断切点为31.05,此时的敏感度为0.74,特异度为0.92。结论:LAP对代谢综合征的诊断效能最高,男性LAP大于26.36、女性LAP大于31.05有助于诊断代谢综合征患者。     

Metabolic cold adaptation in fishes occurs at the level of whole animal, mitochondria and enzyme

Metabolic cold adaptation (MCA), the hypothesis that species from cold climates have relatively higher metabolic rates than those from warm climates, was first proposed nearly 100 years ago and remains one of the most controversial hypotheses in physiological ecology. In the present study, we test the MCA hypothesis in fishes at the level of whole animal, mitochondria and enzyme. In support of the MCA hypothesis, we find that when normalized to a common temperature, species with ranges that extend to high latitude (cooler climates) have high aerobic enzyme (citrate synthase) activity, high rates of mitochondrial respiration and high standard metabolic rates. Metabolic compensation for the global temperature gradient is not complete however, so when measured at their habitat temperature species from high latitude have lower absolute rates of metabolism than species from low latitudes. Evolutionary adaptation and thermal plasticity are therefore insufficient to completely overcome the acute thermodynamic effects of temperature, at least in fishes.