Cardiac regenerative potential of cardiosphere‐derived cells from adult dog hearts

The regenerative potential of cardiosphere‐derived cells (CDCs) for ischaemic heart disease has been demonstrated in mice, rats, pigs and a recently completed clinical trial. The regenerative potential of CDCs from dog hearts has yet to be tested. Here, we show that canine CDCs can be produced from adult dog hearts. These cells display similar phenotypes in comparison to previously studied CDCs derived from rodents and human beings. Canine CDCs can differentiate into cardiomyocytes, smooth muscle cells and endothelial cells in vitro. In addition, conditioned media from canine CDCs promote angiogenesis but inhibit cardiomyocyte death. In a doxorubicin‐induced mouse model of dilated cardiomyopathy (DCM), intravenous infusion of canine CDCs improves cardiac function and decreases cardiac fibrosis. Histology revealed that injected canine CDCs engraft in the mouse heart and increase capillary density. Out study demonstrates the regenerative potential of canine CDCs in a mouse model of DCM.     

Germ band retraction as a landmark in glucose metabolism during <Emphasis Type="Italic">Aedes aegypti</Emphasis> embryogenesis

Background  

The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown.     

大鼠心肌缺血再灌注损伤模型的实验研究

目的 制备一种新型的心肌急性缺血再灌注损伤模型,以探讨一种更符合临床实际需求的实验方法.方法 将20只雌性SD(Sprague-Dawley)大鼠随机分成2组(对照组、实验组),采用结扎主动脉根部引起心肌缺血5min再灌注30 min建立心肌急性缺血再灌注模型;通过应用透射电镜观察心肌细胞超微结构的改变,同时检测心肌组织匀浆丙二醛(Maleic Dialdehyde,MDA)含量、超氧化物歧化酶(Superoxide Dismutase,SOD)活力.结果 透射电镜下超微结构显示实验组较对照组明显加重了心肌组织结构和线粒体的损害;实验组心肌组织MDA明显高于对照组(P<0.01),而SOD明显低于对照组(P<0.01).结论 本实验成功建立了方法简便、易于操作、取材范围广泛的心肌缺血再灌注损伤模型,为心肌缺血再灌注损伤研究提供了一种更为可行的模型.     

Hierarchical phenotypic and epigenetic variation in cloned swine

Cloning by somatic cell nuclear transfer can result in the birth of animals with phenotypic and gene expression abnormalities. We compared adult cloned pigs and adult pigs from naturally bred control females using a series of physiological and genetic parameters, including detailed methylation profiles of selected genomic regions. Phenotypic and genetic analyses indicated that there are two classes of traits, one in which the cloned pigs have less variation than controls and another characterized by variation that is equally high in cloned and control pigs. Although cloning creates animals within the normal phenotypic range, it increases the variability associated with some traits. This finding is contrary to the expectation that cloning can be used to reduce the size of groups involved in animal experimentation and to reproduce an animal, including a pet, with a homogenous set of desired traits.     

Factors affecting the efficiency of introducing precise genetic changes in ES cells by homologous recombination: tag-and-exchange versus the Cre-loxp system

The introduction of genetic modifications in specific genes by homologous recombination provides a powerful tool for elucidation of structure-function relationships of proteins of biological interest. Presently, there are several alternative methods of homologous recombination that permit the introduction of small genetic modifications in specific loci. Two of the most widely used methods are the tag-and-exchange, based on the use of positive--negative selection markers, and the Cre-loxP system, based on the use of a site-specific recombinase. The efficiency of detection of targeting events at different loci using the two systems was compared. Additionally, we analysed how the distance between two gene markers placed within the region of homology of a targeting vector affects the rate at which both markers are introduced into the locus during the homologous recombination event. Our results indicate that the method based on the use of positive--negative selection markers was les s efficient than the Cre-loxP based system, irrespective of locus or type of positive--negative selection. It was also determined that as the distance between the selectable marker and the genetic modification being introduced increases, there is a progressive reduction in the efficiency of detecting events with the desired genetic modification     

Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro

The effects of liquid fluorocarbons as bathing media were determined by use of in vitro neuromuscular preparations. Rat hemidiaphragms were bathed in either oxygenated fluorocarbon (FC) emulsion or standard oxygenated Krebs solution. Contractile force in response to simple supramaximal nerve stimuli as well as to high frequency stimulation was greater, while twitch:tetanus ratio was smaller in FC emulsion. With such medium, post-tetanic potentiation of contraction was also more consistently observed. Indirectly stimulated diaphragms survived longer in FC emulsion. After cessation of oxygenation, oxygen tension (ρO(2)) of the medium declined more rapidly with Krebs than with FC emulsion; ρO(2) directly correlated with force of contraction. Similarly, in the chick biventer cervicis preparation, FC emulsion enhanced nerve-stimulated force of contraction; returning the preparation to standard Krebs solution reversed this phenomenon. Dose-resonse curves of muscle contraction in response to acetycholine and KCl administration were shifted upward during FC emulsion superfusion. Frequency of miniature endplate potentials was lower in FC emulsion than that observed in Krebs solution, measured from the same cell of the rat diaphragm. Resting membrane potentials were also greater in muscle cells sampled from FC emulsion-bathed preparations. These data suggest that FC emulsion is superior to standard Krebs solution as a bathing medium for in vitro neuromuscular preparations by virtue of the high solubility of oxygen in it.