静磁场对单株人体体表正常菌生长影响的研究

本文通过40mT和120mT两种静磁场作用下表皮葡萄球菌生长过程的研究,发现试验所选强度静磁场加速了表皮葡萄球菌在对数生长期的生长速率,而在进入稳定生长期后其生长速率反而低于对照组,但就整个生长周期而言,静磁场作用下表皮葡萄球菌的总量大于对照组,表明了试验所选静磁场对表皮葡萄球菌生长有一定促进作用.     

Biomechanics of haemostasis and thrombosis in health and disease: from the macro‐ to molecular scale

Although the processes of haemostasis and thrombosis have been studied extensively in the past several decades, much of the effort has been spent characterizing the biological and biochemical aspects of clotting. More recently, researchers have discovered that the function and physiology of blood cells and plasma proteins relevant in haematologic processes are mechanically, as well as biologically, regulated. This is not entirely surprising considering the extremely dynamic fluidic environment that these blood components exist in. Other cells in the body such as fibroblasts and endothelial cells have been found to biologically respond to their physical and mechanical environments, affecting aspects of cellular physiology as diverse as cytoskeletal architecture to gene expression to alterations of vital signalling pathways. In the circulation, blood cells and plasma proteins are constantly exposed to forces while they, in turn, also exert forces to regulate clot formation. These mechanical factors lead to biochemical and biomechanical changes on the macro‐ to molecular scale. Likewise, biochemical and biomechanical alterations in the microenvironment can ultimately impact the mechanical regulation of clot formation. The ways in which these factors all balance each other can be the difference between haemostasis and thrombosis. Here, we review how the biomechanics of blood cells intimately interact with the cellular and molecular biology to regulate haemostasis and thrombosis in the context of health and disease from the macro‐ to molecular scale. We will also show how these biomechanical forces in the context of haemostasis and thrombosis have been replicated or measured in vitro.     

Protein accumulation,RNA and soluble amino nitrogen content in developing endosperm of two varieties of Triticum aestivum with high and low protein seed

Summary The kinetics of protein accumulation, the variation in RNA, the soluble amino nitrogen content of developing endosperm of two varieties of Triticum aestivum, with high and low protein content in the mature seed, suggest a possible relation between maintenance of the RNA content and the ability to synthesize protein. A sudden halt in protein accumulation is observed as the RNA starts to decrease. The hypothesis is also advanced that maintenance of the RNA content might, in turn, be dependent on the presence, in the endosperm of developing wheat seed, of a certain level of soluble amino nitrogen which could then play the role of limiting factor for protein synthesis.Publication No. 491 from the Divisione Applicazione delle Radiazioni del C.N.E.N., SCN Casaccia, S.M. di Galeria, Rome, Italy.     

Modulation of the cell cycle during reversible growth inhibition of 3T3 and SV40-3T3 cells with succinylated concanavalin A

Succinylated concanavalin A (ConA), a non-toxic, non-agglutinating derivative of the jack bean lectin ConA inhibits the growth of both normal and SV40-transformed 3T3 cells. The quantitative but not the qualitative growth inhibitory effect of succinyl-ConA can be modulated by the composition of the growth medium. Succinyl-ConA inhibited cells show a low rate of DNA synthesis and accumulate in the G0/G1 phase of the cell cycle. Upon removal of the succinyl-ConA, inhibited cells re-enter the cell cycle synchronously.     

Rotary dialysis: its application to the preparation of large liposomes and large proteoliposomes (protein-lipid vesicles) with high encapsulation efficiency and efficient reconstitution of membrane proteins

An apparatus for rotary dialysis is introduced and described in detail. The component parts are inexpensive, widely available, and relatively easy to modify and assemble. The apparatus achieves increased mixing of the contents of dialysis bags by constant end-over-end rotation. This technique is particularly useful in systems where maximum contact is desired between substances which would tend to partition under standard dialysis conditions. We have applied rotary dialysis to two liposome production methods. These are (i) the calcium-EDTA-chelation method of Papahadjopoulos et al. (1), which produces large unilamellar liposomes from negatively charged phospholipids, and (ii) a procedure for the reconstitution of membrane proteins into liposomes with a large internal aqueous space, which we have developed using the calcium-EDTA-chelation technique as a point of departure. In both techniques, vesicle formation occurs when a calcium-phospholipid precipitate is dissolved by the addition of EDTA. Instead of adding a 150 mM EDTA solution directly, as described in the original method, we have used overnight rotary dialysis against buffer containing 10 mM EDTA at the vesicle formation stage. Materials are encapsulated within the aqueous interior of the vesicles at much higher efficiencies when rotary dialysis is used in either method, compared to efficiencies obtained with direct addition of EDTA (up to 37% of added material vs a maximum published efficiency of 10% for direct addition). Rotary dialysis also promotes the reconstitution of a higher proportion of the membrane proteins present in the dialysis mixture into the bilayer of large liposomes (79 vs 41.6%). It also affects the content of liposomes qualitatively, allowing better reconstitution of the Sendai virus F glycoprotein than does direct addition of EDTA. These effects may be due to the slow time course, the extensive mixing of components, and the low volume-to-phospholipid ratios maintained during vesicle formation.