Modification of albumin with different degrees of the oxidation of SH-groups in the reaction with glucose

A molecule of the major blood protein albumin contains 34 cysteine residues involved in disulfide bonds and one unpaired SH-group of residue Cys34. Normally, 20–30% of these SH-groups are oxidized and form disulfide bonds or the derivatives of sulfenic, sulfinic, and sulfonic acids. The goal of the present work was to study the influence of the degree of oxidation of sulfhydryl groups on the capacity of albumin for glycation. Commercially available human albumin containing 0.4 moles of sulfhydryl groups per 1 mole of the protein (nonmercaptalbumin) was used. Disulfide bonds in this preparation were reduced with dithiothreitol to 0.7 mole/mole to give mercaptalbumin. The preparations were incubated for three weeks with glucose at a concentration of 5 and 50 mM. The content of ketoamine, a glycation product, was determined by the colorimetric method, the content of pentosidine (glycation end product) was analyzed by fluorescence, and the content of SH-groups was determined using the Ellman’s reagent. Changes in the structure and properties of the protein during glycation were studied by fluorescence and HPLC. During the incubation of both albumin preparations with 5 mM glucose, no significant increase in the ketoamine content was observed, whereas the incubation with 50 mM glucose was accompanied by a considerable accumulation of ketoamine. It was found that the greatest amount of ketoamine under these conditions forms in nonmercaptalbumin; in this case, the intensity of tryptophan fluorescence decreases. The intensity of pentosidine fluorescence increases with increasing content of ketoamine. The results obtained enable the conclusion that the oxidation of free SH-groups of the protein changes its conformation; as a result, the glycation of earlier hidden sites becomes possible, and the degree of protein glycation increases.     

Advancement in the derivatizations of the amino groups with the o-phthaldehyde-thiol and with the 9-fluorenylmethyloxycarbonyl chloride reagents

An overview is presented on the advancement of the two most frequently used derivatization protocols applying the o-phthalaldehyde (OPA)-thiol and the fluorenylmethyloxycarbonyl (FMOC) chloride reagents, prior to the high performance liquid chromatographic analysis of amino acids. This review pays special attention (i) to the blank value, to the composition, to the stability and to the life time of the reagents, (ii) to the optimum pH conditions for the interactions and derivatives' elutions, (iii) to the characteristics and behavior of those amino acids which might provide more than one derivative correlating with the molar ratios of the reagent to the reactants, and (iv) on the practical applicability of the optimized protocols.     

Insect metamorphosis: out with the old, in with the new

During insect metamorphosis, the steroid hormone ecdysone activates programmed cell death of larval tissues and the further development of adult tissues. Recent studies suggest that the E93 gene is both necessary and sufficient to target tissues for ecdysone-induced apoptosis.     

坦度螺酮与艾司西酞普兰治疗帕金森病伴抑郁状态的疗效观察

目的观察坦度螺酮与艾司西酞普兰对帕金森病伴抑郁状态的作用及影响。方法将我院收治的帕金森病伴抑郁状态患者110例随机分为对照组和观察组各55例,对照组给予艾司西酞普兰治疗,观察组给予度螺酮治疗,并采用帕金森病综合评分表(UPDRS)和汉密尔顿抑郁量表(HAMD)为量化指标,比较两组患者治疗前及治疗后2、4、6周UPDRS、HAMD指标变化以及不良反应情况。结果两组患者的临床总有效率比较,差异无明显统计学意义(P0.05。治疗6周后,两组患者的UPDRS和HAMD评分与治疗前比较均下降(P0.05),且观察组的下降幅度优于对照组,差异有统计学意义(P0.05)。治疗过程中,两组患者均未出现严重不良反应。结论坦度螺酮的受体选择性高,能有效缓解帕金森病患者常见的情感症状(如抑郁状态)和明显改善帕金森病肌强直症状,且用药安全,是帕金森病伴抑郁状态患者有效抗抑郁剂。