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21.
Frank Serpas Takashi Yanagawa Marcus Pandy 《Computer methods in biomechanics and biomedical engineering》2013,16(1):33-43
A mathematical (computer) model was developed and used to study the mechanics of the human knee during extension exercises employing an isokinetic dynamometer. All parts of the body were fixed to ground, except for the right shank and foot, which were free to move in the parasagittal plane. A linkage attached the dynamometer to the shank; tibiofemoral articulation consisted of single-point contact, allowing both sliding and rolling to occur. Physiologically based representations of ligaments and muscles imparted forces to the shank. A forward dynamics simulation was performed to calculate the forces developed in the knee for isokinetic speeds ranging from 0 (isometric exercise) to 300°/s. Simulations were conducted for a constant-speed phase during isokinetic knee extension exercise. It was assumed for the duration of each simulated exercise that the quadriceps were fully activated and the other muscles were fully deactivated. The force in the anterior cruciate ligament was found to be governed by the force-velocity properties of the quadriceps; the model predicts that 300 deg/sec isokinetic exercise can reduce the force transmitted to the ACL by almost a factor of two compared with that present during isometric knee extension. 相似文献
22.
Robert Black Fabio Fava Niccolo Mattei Vincent Robert Susan Seal Valerie Verdier 《Journal of biotechnology》2011,156(4):370
This review is based on a study commissioned by the European Commission on the evaluation of scientific, technical and institutional challenges, priorities and bottlenecks for biotechnologies and regional harmonisation of biosafety in Africa. Biotechnology was considered within four domains: agricultural biotechnologies (‘Green’), industrial biotechnologies and biotechnologies for environmental remediation (‘White’), biotechnologies in aquaculture (‘Blue’) and biotechnologies for healthcare (‘Red’). An important consideration was the decline in partnerships between the EU and developing countries because of the original public antipathy to some green biotechnologies, particularly genetically modified organisms (GMOs) and food from GM crops in Europe. The study focus reported here was West Africa (Ghana, Senegal, Mali and Burkina Faso).The overall conclusion was that whereas high-quality research was proceeding in the countries visited, funding is not sustained and there is little evidence of practical application of biotechnology and benefit to farmers and the wider community. Research and development that was being carried out on genetically modified crop varieties was concentrating on improving food security and therefore unlikely to have significant impact on EU markets and consumers. However, there is much non-controversial green biotechnology such as molecular diagnostics for plant and animal disease and marker-assisted selection for breeding that has great potential application. Regarding white biotechnology, it is currently occupying only a very small industrial niche in West Africa, basically in the sole sector of the production of liquid biofuels (i.e., bio-ethanol) from indigenous and locally planted biomass (very often non-food crops). The presence of diffused small-scale fish production is the basis to develop and apply new (Blue) aquaculture technologies and, where the research conditions and the production sector can permit, to increase this type of production and the economy of this depressed areas. However, the problems bound to environmental protection must not be forgotten; priority should be given to monitor the risks of introduction of foreign species. Red biotechnologies potentially bring a vast domain of powerful tools and processes to achieve better human health, most notably improved diagnostics by molecular techniques, better targeting of pathogens and a better knowledge of their sensitivities to drugs to permit better treatment.Biosafety regulatory frameworks had been initiated in several countries, starting with primary biosafety law. However, disparate attitudes to the purpose of biosafety regulation (e.g., fostering informed decision-making versus ‘giving the green-light for a flood of GMOs’) currently prevent a needed consensus for sub-regional harmonisation. To date, most R&D funding has come from North America with some commercial interests from Asia, but African biotechnology workers expressed strong desire for (re-)engagement with interested parties from the European Union. Although in some of the visited countries there are very well qualified personnel in molecular biology and biosafety/regulation, the main message received is that human resources and capacity building in-house are still needed. This could be achieved through home-based courses and capacity-building including funds for post-degree research to motivate and retain trained staff. 相似文献
23.
Watson NS Adams C Belton D Brown D Burns-Kurtis CL Chaudry L Chan C Convery MA Davies DE Exall AM Harling JD Irvine S Irving WR Kleanthous S McLay IM Pateman AJ Patikis AN Roethke TJ Senger S Stelman GJ Toomey JR West RI Whittaker C Zhou P Young RJ 《Bioorganic & medicinal chemistry letters》2011,21(6):1588-1592
The discovery and evaluation of potent and long-acting oral sulfonamidopyrrolidin-2-one factor Xa inhibitors with tetrahydroisoquinoline and benzazepine P4 motifs are described. Unexpected selectivity issues versus tissue plasminogen activator in the former series were addressed in the later, delivering a robust candidate for progression towards clinical studies. 相似文献
24.
Tanya Marie Hayes 《Human ecology: an interdisciplinary journal》2007,35(6):733-747
This article compares how public protection of forests and common-property forest institutions serve to control outside encroachment
into frontier forests in Honduras and Nicaragua. The article combines institutional analysis with ethnographically based fieldwork
and analysis of land-cover images to evaluate how property-rights arrangements influence monitoring, enforcement, and compliance
with rules to restrict agricultural expansion in two biosphere reserves in the Mosquitia Corridor. Findings show that territorial
demarcation and common-property rights are important components for frontier forest conservation. In areas with weak enforcement
mechanisms and heavy reliance on social norms over official regulatory measures, the findings suggest that the perceived legitimacy
of tenure arrangements and their respective land-use rules are fundamental to controlling the agricultural frontier.
相似文献
Tanya Marie HayesEmail: |
25.
Yizhong Yan Jianjun Li Yiya Zhang Xiaozhen Peng Tianyao Guo Jirong Wang Weijun Hu Zhigui Duan Xianchun Wang 《Biological research》2014,47(1)
Background
Black widow spider (L. tredecimguttatus) has toxic components not only in the venomous glands, but also in other parts of the body and its eggs. It is biologically important to investigate the molecular basis of the egg toxicity.Results
In the present work, an aqueous extract was prepared from the eggs of the spider and characterized using multiple physiological and biochemical strategies. Gel electrophoresis and mass spectrometry demonstrated that the eggs are rich in high-molecular-mass proteins and the peptides below 5 kDa. The lyophilized extract of the eggs had a protein content of 34.22% and was shown to have a strong toxicity towards mammals and insects. When applied at a concentration of 0.25 mg/mL, the extract could completely block the neuromuscular transmission in mouse isolated phrenic nerve-hemidiaphragm preparations within 12.0 ± 1.5 min. Using whole-cell patch-clamp technique, the egg extract was demonstrated to be able to inhibit the voltage-activated Na+, K+ and Ca2+ currents in rat DRG neurons. In addition, the extract displayed activities of multiple hydrolases. Finally, the molecular basis of the egg toxicity was discussed.Conclusions
The eggs of black widow spiders are rich in proteinous compounds particularly the high-molecular-mass proteins with different types of biological activity The neurotoxic and other active compounds in the eggs are believed to play important roles in the eggs’ toxic actions. 相似文献26.
Antihyperlipidemic Effect of Fisetin,a Bioflavonoid of Strawberries,Studied in Streptozotocin‐Induced Diabetic Rats 下载免费PDF全文
Gopalan Sriram Prasath Sorimuthu Pillai Subramanian 《Journal of biochemical and molecular toxicology》2014,28(10):442-449
Chronic hyperglycemia in diabetes is associated with profound changes in lipid and lipoprotein metabolism, with resultant alterations in particle distribution within lipoprotein classes. In the present study, an attempt has been made to explore the antihyperlipidemic effect of fisetin in streptozotocin‐induced experimental diabetes in rats. Upon fisetin treatment to diabetic rats, the levels of blood glucose were significantly reduced with an improvement in plasma insulin. The increased levels of lipid contents in serum, hepatic, and renal tissues observed in diabetic rats were normalized upon fisetin administration. Also, the decreased levels of high‐density lipoprotein cholesterol, and increased levels of low‐density lipoprotein (LDL) and very LDL (VLDL) cholesterol in serum of diabetic rats were normalized. Oil Red O staining established a large number of intracellular lipid droplets accumulation in the diabetic rats. Fisetin treatment exacerbated the degree of lipid accumulation. The results of the present study exemplify the antihyperlipidemic property of the fisetin. 相似文献
27.
从云南西北部土样中分离到一株卡瑞苯西思伯克霍尔德氏菌(Burkholderia caribensis),它在氯乙酸培养基中能产生较高活性的卤乙酸脱卤酶。经硫酸铵盐析、DEAE SephadexA50柱层析、羟基磷灰石柱层析、Sephadex G200 凝胶过滤后,获得电泳纯酶。用SDSPAGE测定酶分子量为46kD。水解氯乙酸的Km值为3.7×10-3mol/L。酶反应的最适温度为40℃,最适pH值为9.5。金属离子及CN-、EDTA对该酶有不同程度的影响,Hg2+和CN-则对该酶有强烈的抑制作用。 相似文献
28.
水稻化感作用及其生理生化特性的研究 总被引:98,自引:21,他引:77
选用具有强化感作用的6个水稻品种为供体,大田稗草为受体,研究了水稻化感作用及生理生化特性,结果表明,提高水稻叶片浸提液浓度,可以相应增强对稗草生长的抑制效果,这种抑制效果与杂草的种植密度呈负相关;化感水稻叶片浸提液能显著抑制物质稗草体内超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性,从而影响其生长;苯丙氨酸氨解酶(PAL)的活性大小与酚类物质的含量吴正相关;多种酚类物质的化感作用之间可能是增效的,也可能是拮抗的。 相似文献
29.
苦荞种子胰蛋白酶抑制剂的分离纯化及部分性质研究 总被引:14,自引:0,他引:14
采用凝胶层析及离子交换层析等方法,从苦荞种子中分离出一组胰蛋白酶抑制剂(TBTI-Ⅰ、Ⅱ).对其性质研究表明:两个组分均对胰蛋白酶有较强的抑制作用,对胰凝乳蛋白酶抑制作用较弱,其中TBTI-Ⅱ的抑制作用大于TBTI-Ⅰ,两者对胃蛋白酶、木瓜蛋白酶及枯草杆菌蛋白酶均无抑制作用.用SDS-聚丙烯酰胺凝胶电泳和SephadexG-100凝胶层析分别对纯化产物进行分析得出TBTI-Ⅰ和TBTI-Ⅱ的近似分子量分别为15.0kD和18.0kD.TBTI-Ⅰ、Ⅱ都具有较高的热稳定性,在100℃处理10min后可保留86%左右的抑制活性.TBTI在酸性环境下较为稳定,在pH2.0条件下保温1h,仍保留75%的抑制活性.用Lineveaer-Burk作图法得知,该抑制剂属竞争性抑制类型,TBTI-Ⅱ的Ki值为3.59×10-7mol/L(以BAPNA为底物),对胰蛋白酶的摩尔抑制比为1∶1.4. 相似文献
30.
夏威环毛蚓纤溶酶的分离纯化及部分性质研究 总被引:6,自引:0,他引:6
以夏威环毛蚓(Pheretima hawayana)为材料,采用磷酸盐缓冲液抽提、(NH4)2SO4分段盐析,离子交换树脂 D290、 Sephadex G-100和 DEAE-sephadex A-50三种连续柱层析方法得到一种在 PAGE上显示单一区带的纤溶酶组份。采用凝胶柱层析和 SDS-PAGE测其分子量为 12 000和 12300,由一条肽链组成。该酶具有强烈的纤溶活力和水解BAEE的活力,能直接作用纤维蛋白和间接激活纤溶酶原。其最适反应温度为45℃,最适反应pH为8.0。该酶水解BAEE的活力可被Na+、K+、Mg2+、Hg2+、金属离子和EDTA、巯基乙醇抑制,Ca+则有激活作用。该酶中性糖含量为5%,氨基酸组成中Arg、Len含量较多. 相似文献