Fluorescence and photobleaching dynamics of single light-harvesting complexes

Single light-harvesting complexes LH-2 from Rhodopseudomonas acidophila were immobilized on various charged surfaces under physiological conditions. Polarized light experiments showed that the complexes were situated on the surface as nearly upright cylinders. Their fluorescence lifetimes and photobleaching properties were obtained by using a confocal fluorescence microscope with picosecond time resolution. Initially all molecules fluoresced with a lifetime of 1 ± 0.2 ns, similar to the bulk value. The photobleaching of one bacteriochlorophyll molecule from the 18-member assembly caused the fluorescence to switch off completely, because of trapping of the mobile excitations by energy transfer. This process was linear in light intensity. On continued irradiation the fluorescence often reappeared, but all molecules did not show the same behavior. Some LH-2 complexes displayed a variation of their quantum yields that was attributed to photoinduced confinement of the excited states and thereby a diminution of the superradiance. Others showed much shorter lifetimes caused by excitation energy traps that are only ≈3% efficient. On repeated excitation some molecules entered a noisy state where the fluorescence switched on and off with a correlation time of ≈0.1 s. About 490 molecules were examined.     

颞颌关节继发性滑膜炎的临床诊断

颞颌关节滑膜炎分为原发性和继发性两种，颞颌关节紊乱综合症的滑膜炎为继发性滑膜炎。本文通过对１０６例颞颌关节紊乱综合症患者的临床检查、关节许氏位以及关节上腔造影的Ｘ线检查，同时对４２例进行了关节内窥镜检查，在此基础上探讨了继发性滑膜炎的临床诊断标准．作者认为急性滑膜炎主要是以关节疼痛和滑膜血管的改变为主，慢性滑膜炎的临床症状与滑膜组织改变以及关节骨组织的改变均有关系。     

竹红菌甲素敏化S-180肿瘤细胞膜的光氧化反应及机理探讨

本文研究了竹红菌甲素(简称甲素)对S-180肿瘤细胞膜的作用。结果表明,甲素结合光照可引起S-180肿瘤细胞膜蛋白质交联、脂质过氧化产物MDA含量增加。但在SDS-PAGE分析中观察到的高分子蛋白质交联带并非由MDA所引起。甲素同样可引起小牛胸腺组蛋白光氧化、发生分子交联,并可敏化色氨酸、酪氨酸和组氨酸的无氧化。     

Frictional transition of pesticides from protective clothing

Frictional transition of pesticides, the transition of the dried pesticide due to rubbing, from protective clothing was investigated by using an AATCC standard crockmeter. One insecticide (carbaryl) and two herbicides (atrazine and metolachlor) were studied, together with three protective clothing materials [cotton, polyester, and polyester/cotton (65/35) blend] and three crock fabrics (cotton, nylon, and silk). The effects of the properties of pesticide, fabrics, water, and perspiration on the frictional transition are discussed. The experiment showed that up to 12% of the pesticide could transfer from contaminated protective clothing to the skin through rubbing. Choosing the right materials for protective clothing and underwear would greatly decrease the frictional transition of the pesticide.     

Radix Tripterygium wilfordii--a Chinese herbal medicine with potent immunosuppressive properties

Radix Tripterygium wilfordii Hook-F (TW) is a Chinese herbal medicine that has been reported to be effective in the treatment of various autoimmune disorders in experimental animals and man. Little is known about the immunosuppressive mechanism of action of this medicine. We demonstrate herein that TW is capable of inhibiting several afferent immune functions including the in vitro response of human peripheral blood mononuclear cells to both mitogen and alloantigen, and the generation of cytotoxic T cells. This inhibition is likely mediated through a reduction in both IL-2 production and IL-2 responsiveness. TW evidenced little capability of impairing IL-2 receptor expression, or efferent immune mechanisms such as cell-mediated cytotoxicity or natural killer cell-mediated cytotoxicity. The immunosuppressive effects of TW were reversible except at the highest concentration tested, 2.4 micrograms/ml, and there was no evidence of TW-mediated cell-well damage as evidenced by trypan-blue exclusion. TW, or some of its constituents, may be important new agents to be studied for immunosuppression in organ transplantation.     

新型麻醉药异丙酚的氧化动力学

采用高效液相色谱法测定了异丙酚在不同温度下及其甲醇 水（Ｖ∶Ｖ＝７０∶３０）混合溶液在不同ｐＨ值下的反应速率常数，并求出了异丙酚氧化反应的活化能，结果表明ｐＨ值与温度对异丙酚的氧化动力学均有影响