Effect of high hydrostatic pressure on chicken myosin subfragment-1

Hydrostatic pressure-induced structural changes in subfragment-1 (S1) of myosin molecule were studied. ATP-induced emission spectra of S1 were used to detect global structural change of S1 by pressure treatment. The fluorescence intensity of unpressurized S1 increased by addition of ATP. The increment of fluorescence of pressurized S1 up to 150 MPa was almost the same as control, whereas it became smaller above 200 MPa. ATP binding ability of S1 examined using 1, N⁶-ethenoadenosine 5′-diphosphate (-ADP) indicated that the binding of -ADP to S1 decreased in the range of 250–300 MPa. S1 pressurized below 250 MPa and unpressurized S1 similarly bound to F-actin, although binding of S1 pressurized above 250 MPa decreased. Electron microscopic observation revealed arrowhead structure in control acto-S1, while disordered arrowhead structure was observed in acto-S1 prepared from pressurized S1 at 300 MPa. S1 pressurized below 250 MPa retained the same actin activated ATPase activity as the control, whereas the activity decreased to 60% at 300 MPa. Pressure treated S1 was easily cleaved by tryptic digestion into three domains, i.e. 27 kDa (N-terminal), 50 and 20 kDa (C-terminal) fragments, which were the same as those in unpressurized one. It is concluded that pressure-induced global structural changes of S1 begin to occur about 150 MPa, and the local structural changes in ATPase and actin binding sites followed with elevating pressure to 250–300 MPa.     

Nitric oxide and blood pressure in mice lacking extracellular-superoxide dismutase

Nitric oxide is a major vasorelaxant and regulator of the blood pressure. The blood vessels contain several active sources of the superoxide radical, which reacts avidly with nitric oxide to form noxious peroxynitrite. There are large amounts of extracellular-superoxide dismutase (EC-SOD) in the vascular wall. To evaluate the importance of EC-SOD for the physiology of nitric oxide, here we studied the blood pressure in mice lacking the enzyme. In chronically instrumented non-anaesthetized mice there was no difference in mean arterial blood pressure between wild-type controls and EC-SOD mutants. Extensive inhibition of nitric oxide synthases with N -monomethyl- l -arginine however resulted in a larger increase in blood pressure, and infusion of the nitric oxide donor nitrosoglutathione caused less reduction in blood pressure in the EC-SOD null mice. We interpret the alterations to be caused by a moderately increased consumption of nitric oxide by the superoxide radical in the EC-SOD null mice. One role of EC-SOD may be to preserve nitric oxide, a function that should be particularly important in vascular pathologies, in which large increases in superoxide formation have been documented.     

Study of intraarticular pressures in the elbow joints

The purpose of this study was to describe pressure originating in the six elbow articular compartments after muscular contractions. Ten cryopreserved cadaveric arms were dissected and the insertional tendons and capsuloligamentous tissues were preserved. The specimens were placed in a custom-made device. Elbow position was established at 90° flexion with the forearm in a neutral position and the wrist extended at 0°. Tekscan sensors sere used for measuring intraarticular pressures.Without loading the elbow, the humeroradial joint received the lowest pressure, and, among the humeroulnar joints, the highest pressure was found in the anterolateral compartment. After loading the epitrochlear muscles to the maximum (5.0 kg), the pressure increased in the anteromedial joint (0.6 kg to 3.3 kg) and decreased in the posteromedial and anterolateral joints (4.2 kg to 0.3 kg and 4.2 kg to 0.9 kg, respectively). After the same loading in the epicondylar muscles, the pressure increased in the anterolateral and humeroradial joints (4.2 kg to 8.2 kg and 0.2 kg to 1.0 kg respectively), but decreased in the posterolateral joint (3.4 kg to 1.0 kg). The pressure distribution patterns among the humeroulnar compartments depend on the muscle geometries and their origins. Understanding these patterns can be useful in applying physiotherapeutic treatments for reinforcement of different muscular groups in order to decrease pressure in certain articular compartments.     

Chronobiologically interpreted ambulatory blood pressure monitoring: past,present, and future

Research at the Halberg Chronobiology Center focused to a large extent on the monitoring of blood pressure (BP) and heart rate (HR). Self-measurements and later ambulatory BP monitoring yielded new knowledge of interest to basic science and clinical practice. After a brief review of BP measurement, we outline developments in methods of data analysis that paralleled technological advances in the measurement of BP. We review work done in cooperation with colleagues worldwide to illustrate how a chronobiological approach led to the mapping of spontaneous circadian and other rhythms for the derivation of refined reference values and to the assessment of response rhythms underlying chronotherapy. BIOCOS members work in different fields, spanning from cardiology and nutrition to obesity, diabetes, exercise physiology and rehabilitation, but all strive for “pre-habilitation”. The early recognition of increased risk can prompt the timely institution of prophylactic intervention. As technology continues to improve, studies on groups are complemented by longitudinal self-surveillance for health maintenance. Longitudinal records serve for the investigation of environmental influences on human physiology, the topic of chronomics. As current advances in technology and wireless communication will likely impact the future of healthcare, chronobiological methods and concepts should be an integral part of this seachange.     

MitoQ对高糖诱导的心肌细胞线粒体功能影响

目的:探讨MitoQ对高糖诱导的心肌细胞线粒体功能影响。方法:常规获取与纯化SD大鼠新生仔鼠心肌细胞,分为对照组、高糖组、实验组。对照组用含10%血清的DMEM培养基(5.5 mmol/L葡萄糖)培养;高糖组用含血清的高糖DMEM培养基(33mmol/L葡萄糖)培养;实验组用含血清的高糖DMEM培养基(33 mmol/L葡萄糖)和MitoQ。MTT法检测心肌细胞存活率,氯离子荧光探针检测细胞内氯离子浓度,流式细胞术检测各组心肌细胞凋亡率,超氧化物阴离子荧光染色检测心肌细胞活性氧(reactive oxygen,ROS)含量,利用ATP检测试剂盒检测心肌细胞中的ATP水平,Western blot法检测心肌细胞胱天蛋白酶3(caspase-3)蛋白水平。结果:与对照组相比,高糖组的心肌细胞增凋亡率、ROS产生、氯离子相对浓度均明显增加,ATP显著降低(P0.05),细胞内caspase-3蛋白表达显著上升(P0.05);与高糖组相比,实验组凋亡率降低,ROS产生、细胞内caspase-3蛋白表达均显著降低(P0.05)。结论:高糖会引起心肌细胞线粒体障碍,造成心肌细胞凋亡,MitoQ可降低细胞内ROS和caspase-3水平,抑制心肌细胞凋亡,改善心肌细胞线粒体功能。     

两种压疮评估量表在骨科患者中的应用研究

目的:比较分析Waterlow和Norton两种压疮评估量表在预测骨折患者压疮中的临床效果。方法:选取某院骨科患者186例,由2名临床护士分别用2种量表对患者进行皮肤评估和量表评分,两者分别独立进行,比较分析两种量表对患者压疮的预测效果。结果:患者共发生压疮5例,发生率为2.69%(5/186);Waterlow量表和Norton量表的临界预测值分别为17分和14分;而二者的受试者工作特征曲线(Receiver Operator Curve,ROC)下面积分别为0.647和0.439。结论:Waterlow量表包含了与骨科疾病相关的压疮危险因素,更加适用于预测骨科患者压疮,但仍需要做进一步改进。     

Pressure sensing using a completely flexible organic transistor

In this paper, we report on pressure sensors based on completely flexible organic thin film transistors (OTFTs). A flexible and transparent plastic foil (Mylar) is employed both as substrate and gate dielectric. Gold source and drain electrodes are patterned on the upper side of the foil while the gate electrode lies on the opposite side; a vacuum-sublimed pentacene film is used as active layer. The pressure dependence of the output current has been investigated by applying to the gate side of the device a mechanical stimulus by means of a pressurized airflow. Experimental results show a reversible dependence of the current on the pressure. The data analysis suggests that the current variations are due to pressure-induced variations of mobility, threshold voltage and possibly contact resistance. The drain current variation is reproducible, linear and reversible even though it displays a hysteresis. Moreover, the sensor responds very fast to the mechanical stimulus (i.e. within tens–hundreds of milliseconds) but the time required to reach the steady state is much higher (tens–hundreds of seconds). Electrical characteristics with and without applied pressure have been carried out in air without any extra ad hoc read-out circuit or equipment.

The reported devices show potential advantages of flexibility of the structure, low cost and versatility of the device structure for sensor technologies. Many innovative and attractive applications as wearable electronics, e-textiles, e-skin for robots can be considered.     

Thermotropic and barotropic phase transitions in bilayer membranes of ether-linked phospholipids with varying alkyl chain lengths

The bilayer phase transitions of a series of ether-linked phospholipids, 1,2-dialkylphosphatidylcholines containing linear saturated alkyl chain (C_n = 12, 14, 16 and 18), were observed by differential scanning calorimetry (DSC) under ambient pressure and light-transmittance measurements under high pressure. The thermodynamic quantities of the pre- and main-transitions for the ether-linked PC bilayer membranes were calculated and compared with those of a series of ester-linked PCs, 1,2-diacylphosphatidylcholines. The thermodynamic quantities of the main transition for the ether-linked PC bilayers showed distinct dependence on alkyl-chain length and were slightly different from those of the ester-linked PC bilayers. From the comparison of thermodynamic quantities for the main transition between both PC bilayers, we revealed that the attractive interaction in the gel phase for the ether-linked PC bilayers is weaker than that for the ester-linked PC bilayers. Regarding the pretransition, although changes in enthalpy and entropy for both PC bilayers were comparable to each other, the volume changes of the ether-linked PC bilayers roughly doubled those of the ester-linked PC bilayers. The larger volume change results from the smallest partial molar volume of the ether-linked PC molecule in the interdigitated gel phase. Further, we constructed the temperature-pressure phase diagrams for the ether-linked PC bilayers by using the phase-transition data. The region of the interdigitated gel phase in the phase diagrams was extended by applying pressure and by increasing the alkyl-chain length of the molecule. Comparing the phase diagrams with those for the ester-linked PC bilayers, it was proved that the phase behavior of the ester-linked PC bilayers under high temperature and pressure is almost equivalent to that of the ether-linked PC bilayers in the vicinity of ambient pressure.     

Logit model in prospective coronary heart disease (CHD) risk factors prediction in Saudi population

Analysis through logistic regression explored to investigate the relationship between binary or multivariable ordinal response probability and in one or more explanatory variables. The main objectives of this study to investigate advanced prediction risk factor of Coronary Heart Disease (CHD) using a logit model. Attempts made to reduce risk factors, increase public or professional awareness. Logit model used to evaluate the probability of a person develop CHD, considering any factors such as age, gender, high low-density lipoprotein (LDL) cholesterol, low high-density lipoprotein (HDL) cholesterol, high blood pressure, family history of CHD younger than 45, diabetes, smoking, being post-menopausal for women and being older than 45 for men. Logit concept of brief statistics described with slight modification to estimate the parameters testing for the significance of the coefficients, confidence interval fits the simple, multiple logit models. Besides, interpretation of the fitted logit regression model introduced. Variables showing best results within the scientific context, good explanation data assessed to fit an estimated logit model containing chosen variables, this present experiment used the statistical inference procedure; chi-square distribution, likelihood ratio, Score, or Wald test and goodness-of-fit. Health promotion started with increased public or professional awareness improved for early detection of CHD, to reduce the risk of mortality, aimed to be Saudi vision by 2030.     

Fluid Dynamics Simulating Experiment of Pressure Gradient for Assimilate Translocation in Sieve Tubes

According to the similitude theory of fluid mechanics, a pressure-driven experiment in a sieve tube model has been performed. The relationships between the pressure gradient and the transport velocities at the various diameters of sieve pore have been obtained. The experimental data were compared with the theoretical prediction based on the poiseuille equation. The result shows that the pressure gradient required for translating the assimilate is directly proportional to the translating velocity, which agrees with Poiseuille equation. However, the resistance of the sieve plate to flow is much more than that estimated by the previous theory. Even though the translating velocity is a normal level and the diameter of the sieve tube is a typical size, the pressure gradient required for flow is about 1 bar/m. It will increase sharply with the decrease of the diameter of sieve pore. The ratios of the pressure gradients measured in the test to that predicted by Poiseuille equation are about 2–4 for the five kinds of diameters of Sieve pore. Additionally, a simulating test of the pores being partly plugged has been performed. The result shows that the pressure gradients measured are greatly beyond the range that may be kept in plants. This study will be helpful to assess Munch hypothesis.