Skeletal muscle: A paradigm for testing principles of bioenergetics

Muscular activity converts chemical energy into useful work and metabolism restores muscle to its original state. This essay explores the organization and interactions of the regulatory system(s) which allow this energy balance to occur. The term energy balance is used in a biochemical rather than a thermodynamic sense—concerned not with deductions from the physical principles of thermodynamics, but rather with those enzymatic processes which nature evolved and which operate at remarkably fixed stoichiometry. Energy balance is a statement of conservation of energy put into biochemical observables.³¹P NMR spectroscopy is one of the most useful techniques for investigating these questions quantitatively under physiological conditionsin vivo. The author (1) describes the rules or principles of biochemical energy balance; (2) discusses sample results from human muscle to demonstrate its use in studying this class of questions; (3) presents a simple model of integrated cellular respiration to demonstrate its sufficiency to account for the main observations.     

Occurrence,properties and biological implications of the active uptake of water vapour from the atmosphere in Psocoptera

Water vapour absorption is shown to occur in 22 species of Psocoptera inhabiting diverse environments and representing all major groups of this insect order. Evidently the faculty is a common feature of the whole order and it seems not to be related to specific environmental conditions. For the first time water vapour uptake could be demonstrated in fully winged and flying insects. The critical equilibrium humidities vary considerably among different species ranging from 58 to 85% r.h. Marked interspecific differences are also observed in water loss and uptake rates but no clear correlation with habitat or systematic group is recognizable. The uptake rates of Psocoptera are among the highest of all arthropods investigated so far. From weight recordings with a sensitive microbalance it could be seen that continuous operation of the uptake mechanism is restricted to limited periods of time of less than 1 hr regardless of the water status of the animals. Initiation and termination of the uptake process are abrupt and continuous uptake proceeds at a constant rate at a given relative humidity. Uptake rates are humidity-dependent decreasing with falling relative humidity whereas the adjustment of the equilibrium level of body water is independent of ambient humidity. Equilibrium is maintained by intermittent operation of the uptake mechanism within ca. 3% of body water mass. The uptake mechanism exhibits marked sensitivity to starvation in most members of the Psocomorpha. Some features of the uptake process of Psocoptera are in close agreement with those of Mallophaga reflecting the close relationship between the two groups.     

On structure and functioning of ecosystem in a Salmon lake

The seasonal dynamics of the main components of the ecosystem as well as the vertical distribution of their biomass and production were studied in the salmon lake Dalnee at Kamchatka Peninsula. The data received were used for the construction of schemes of energy balance during two successive years: 1970 and 1971, which were different by their thermic regime. Analysis of schemes showed that during a colder season the food chain was shorter and more effective in relation of the use of primary production by zooplankton. Through the detritus pool the ecosystem used from 16% (1971) up to 70% (1970) of energy of primary production. Seasonal succession includes two main phases -autotrophic and heterotrophic. The energy balance of the planktonic community at these two phases is given.     

森林蒸散模型参数的确定

以长白山阔叶红松林为研究对象,利用长白山阔叶红松林气象观测塔安装的常规气象梯度观测系统、开路涡动相关系统的观测数据,依据空气动力学基本理论与能量平衡方程建立了森林蒸散机理模型,确定了模型参数,即风速廓线稳定度订正函数φ_m、温度廓线稳定度订正函数φ_h和零平面位移高度d.其中,研究地的零平面位移高度d为17.8m,是平均冠层高度(26m)的0.68.同时,给出了φ_m和φ_h随梯度理查逊数R_i变化的数学表达式.     

瑞芬太尼靶控输注对宫颈癌根治术患者麻醉苏醒质量、应激反应及Th1/Th2免疫平衡的影响

摘要 目的：观察瑞芬太尼靶控输注对宫颈癌根治术患者麻醉苏醒质量、应激反应及辅助T细胞（Th）1/Th2免疫平衡的影响。方法：按照随机数字表法将2023年1月到2023年6月期间我院接受的120例宫颈癌根治术患者分为舒芬太尼组（n=60,舒芬太尼麻醉）和瑞芬太尼组（n=60,瑞芬太尼麻醉）。对比两组的麻醉苏醒质量、应激反应指标[皮质醇（Cor）、去甲肾上腺素（NE）、血管紧张素1（Ang-1）、血管紧张素2（Ang-2）]、Th1/Th2免疫平衡指标[包括Th1、Th2及调节性T细胞（Treg）、Th1/Th2比值],术后记录不良反应发生情况。结果：与舒芬太尼组相比,瑞芬太尼组的应激呼吸恢复时间、睁眼时间、拔管时间更短（P<0.05）。术后1 d,两组Cor、NE、Ang-1、Ang-2升高,但瑞芬太尼组低于舒芬太尼组（P<0.05）。术后1 d,两组Th1、Treg、Th1/Th2升高,但瑞芬太尼组低于舒芬太尼组;Th2下降,但瑞芬太尼组高于舒芬太尼组（P<0.05）。两组不良反应发生率组间对比未见差异（P>0.05）。结论：瑞芬太尼靶控输注用于宫颈癌根治术患者,可改善麻醉苏醒质量,减轻应激反应,调节Th1/Th2免疫平衡,且不增加不良反应的发生率,效果较好。     

限制能量平衡膳食联合运动干预对肥胖儿童身体成分、脂质代谢及肠道菌群的影响

摘要 目的：观察限制能量平衡膳食联合运动干预对肥胖儿童身体成分、脂质代谢及肠道菌群的影响。方法：选取2020年4月至2022年10月期间浙江大学医学院附属儿童医院收治的肥胖儿童104例作为研究对象。按照随机数字表法将肥胖儿童分为对照组（n=52,限制能量平衡膳食）和观察组（n=52,限制能量平衡膳食联合运动干预）。对比两组身体成分、脂质代谢及肠道菌群变化情况。结果：观察组干预2个月后体重、体质量指数（BMI）、去脂体重、脂肪量、体脂率低于对照组（P<0.05）。观察组干预2个月后总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白胆固醇（LDL-C）低于对照组;高密度脂蛋白胆固醇（HDL-C）高于对照组（P<0.05）。观察组干预2个月后肠球菌、大肠杆菌低于对照组;乳杆菌、双歧杆菌高于对照组（P<0.05）。结论：限制能量平衡膳食联合运动干预可有效改善肥胖儿童身体成分,调节脂质代谢及肠道菌群平衡。     

Oncogenic potential of Nrf2 and its principal target protein heme oxygenase-1

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential component of cellular defense against a vast variety of endogenous and exogenous insults, including oxidative stress. Nrf2 acts as a master switch in the circuits upregulating the expression of various stress-response proteins, especially heme oxygenase-1 (HO-1). Paradoxically, however, recent studies have demonstrated oncogenic functions of Nrf2 and its major target protein HO-1. Levels of Nrf2 and HO-1 are elevated in many different types of human malignancies, which may facilitate the remodeling of the tumor microenvironment making it advantageous for the autonomic growth of cancer cells, metastasis, angiogenesis, and tolerance to chemotherapeutic agents and radiation and photodynamic therapy. In this context, the cellular stress response or cytoprotective signaling mediated via the Nrf2–HO-1 axis is hijacked by cancer cells for their growth advantage and survival of anticancer treatment. Therefore, Nrf2 and HO-1 may represent potential therapeutic targets in the management of cancer. This review highlights the roles of Nrf2 and HO-1 in proliferation of cancer cells, their tolerance/resistance to anticancer treatments, and metastasis or angiogenesis in tumor progression.     

Ecosystem responses to changes in plant functional type composition: An example from the Patagonian steppe

Abstract. Grass cover along a grazing intensity gradient in Patagonia decreases, whereas bare soil and shrub cover increases. Our objective was to study the effect of a change in the dominant plant functional type on soil water balance, primary production, herbivore biomass, roughness, and albedo. Using a soil water balance model, we found increases in evaporation and deep drainage, and a decrease in total transpiration along the grazing intensity gradient. Above-ground primary production, estimated from transpiration, decreased along the grazing intensity gradient because shrubs did not fully compensate for the decrease in grass production. Using a statistical model, we calculated herbivore biomass from estimates of above-ground primary production. Estimated herbivore biomass was lowest in the shrub-dominated extreme of the grazing gradient. Roughness increased from the grass-dominated to the shrub-dominated community. Albedo had a maximum at an intermediate position along the gradient. Our results suggest that changes in plant functional type composition, independent of changes in biomass, affect ecosystem functioning and the exchange of energy and material with the atmosphere. Grasses and shrubs proved to be appropriate plant functional types to link structure and function of ecosystems.     

Mexican Arnica Anti–Inflammatory Action: Plant Age is Correlated with the Concentration of Anti–Inflammatory Sesquiterpenes in the Medicinal Plant <Emphasis Type="Italic">Heterotheca inuloides</Emphasis> Cass. (Asteraceae)<Superscript>1</Superscript>

Mexican Arnica Anti–Inflammatory Action: Plant Age Is Correlated with the Concentration of Anti–inflammatory Sesquiterpenes in the Medicinal Plant Heterotheca inuloides Cass. (Asteraceae). Mexican árnica (Heterotheca inuloides Cass.) is a widely used anti–inflammatory medicinal plant in Mexican folk medicine. Although it has been suggested that plant age, fertilization, and harvesting regime influence the concentration of secondary compounds affecting the therapeutic activity of the plant, the effect of these variables on the concentration of the Mexican árnica anti–inflammatory compounds was not known. We quantified anti–inflammatory sesquiterpenes (caryolan–1, 9β–diol, cadalen–15–oic acid, 7–hydroxycadalene, 4–hydroxy–2–isopropyl–4, 7–dimethyl–1[4H] naftalinone, 7–hydroxy–4αH–3, 4–dihydrocadalene, β–caryophyllene, and β–caryophyllene epoxide) in Mexican árnica plants subjected to fertilization and successive harvests of flowering stems, conditions that mimic the cultivation and harvesting for árnica in México. Fertilization and successive harvesting and their interaction had no significant effect on the concentration of anti–inflammatory compounds. However, the concentrations of these compounds were 60% higher in flowering stems from 15–month–old plants than in those from 4– or 8–month–old plants and was independent of the number of harvests and fertilization regime applied.     

干旱绿洲灌区大白菜施磷效应与磷肥投入阈值

针对磷肥施用量大且利用率不高的问题,通过2011—2013年在甘肃省农业科学院张掖绿洲灌区农业生态环境重点野外台站进行定位试验,研究了不同施磷量对露地大白菜产量、磷肥利用率以及磷素平衡的影响.结果表明:大白菜产量随施磷量的增加先增加后呈下降的趋势.在施磷量为112.52 kg·hm^-2时产量达到最高(5489.1 kg·hm^-2),且显著高于其他处理,与不施磷处理相比,增产13.3%~23.8%,此时磷肥利用率为14.2%.土壤中土壤有效磷(Olsen-P)和可溶性总磷(CaCl-P)呈现较好的正相关性,土壤Olsen-P含量为24.22 mg·kg-12时对应的施磷量为111.1 kg·hm^-2,表明当土壤中Olsen-P含量小于24.22 mg·kg-1时,土壤中的磷素不发生盈余,对环境不造成污染.当施磷量为60.17 kg·hm^-2时,磷输入与输出达到平衡,即此施磷量水平能满足作物的需求.结合研究区的土壤肥力状况,综合产量、磷肥利用率及土壤有效磷含量,干旱绿洲灌区磷肥投入阈值在60.17~112.52 kg·hm^-2时,能保证露地大白菜高产,并且不会造成环境污染.