Met-enkephalin circulates in human plasma

The physiological roles of Met-enkephalin and Leu-enkephalin are still unknown. They may act as neurotransmitters in the central and peripheral nervous systems. Met-enkephalin has been detected in several species in a variety of tissues including brain, spinal cord and gut using bioassays, opiate receptor assays and radioimmunoassays (RIA). It has also been detected in human gut immunocytochemically and in human brain and cerebrospinal fluid by opiate receptor assay and RIA. However, all reported assays show some degree of cross-reaction with Leu-enkephalin and unequivocal differentiation between the two enkephalins and the larger endorphins has not always been possible. Thus the existence of Met-enkephalin in human tissues and fluids remains in doubt. Using a highly specific RIA, we have now obtained evidence that Met-enkephalin-like material circulates in the plasma of normal subjects and may be secreted by the adrenal gland. Chromatographically the material exists in plasma mainly as the intact pentapeptide and not as the biologically inactive degradation product Gly-Gly-Phe-Met as would be expected from metabolic studies.     

人血浆和脑脊液中地卡因的RP-HPLC法测定

建立人血浆和脑脊液中地卡因的检测方法.方法：用RP-HPLC法将地卡因同人血浆和和脑脊液中的杂质分离.结果：建立了用RP-HPLC法测定地卡因在血浆和和脑脊液中浓度的色谱条件.色谱柱为Lichrospher C18（4.6×250mm,5μm）,流动相为乙腈-水-冰醋酸（40∶60∶0.2）.在0.1-9.0mg.L^-1范围内地卡因峰面积与内标峰面积之比与浓度线性关系良好,最低检测浓度为0.03mg.L^-1,血浆回收率为90.3%-99.1%,日内RSD为1.8%-5.6%,日间RSD为3.1%-7.7%.脑脊液回收率为88.7%-96.2%,日内RSD为3.5%-5.9%,日间RSD为6.1%-10.5%.结论：样品处理简便快速,测定方法准确可靠,适合于地卡因的临床治疗药物监测及药代动力学研究.     

物质的本性

 当前随着物质认识的不断深入,对物质的理解更加纷乱、模糊.本文通过阐述感官的有限性,提出了认识物质的局限性;通过阐述物质认识进展,得出物理学面临重建的结论;最后,在阐述一元二态物质观的基础上,提出了一个新的物理统一方法.