Objective To investigate etiology of the 18 -45 years young ischemic stroke and risk factors .Methods We retro-spectively analyzed clinical data of 106 cases patients with ischemic stroke ,carotid ultrasound ,MRA ,CTA ,DSA results analyzed e-tiology ,type .compared patients and the same period youth for the medical check with risk factors .Results The proportion of LAA、SOE in low ages had significant differences with high age(P<0 .05) .The proportion of LAA was 29 .2% and the proportion of SUE was 25 .4% ,On hypertension ,hyperlipidemia ,drinking ,smoking ,obesity ,diabetes ,heart disease ,high homocystine ,young stroke group had significant differences with young control group (P<0 .05) .Conclusion Youth main cause of ischemic stroke is large artery atherosclerotic stroke and unknown cause of stroke .The main youth ischemic stroke risk factors are smoking ,hyperten-sion ,hyperlipidemia ,diabetes ,drinking ,heart disease .

【Objective】 To improve method for determinating of biological potency of IgG Fc fragment in Chinese Pharmacopoeia and establish a method which is suitable for enzyme-labeled instrument. 【Methods】 The biological properties of FC fragment of IVIG in Chinese Pharmacopiea(General 3514) was adjusted, including sensitization process, sample treatment and dynamic curve parameters. Meanwhile, the kinetic curve of hemolysis was fitted with Origin, which made the method more suitable for enzyme plate. The biological properties of Fc fragment of IVIG was calculated by kinetics curve reaction of reference and sample. 【Results】 The method are stable, the RSD of repeatability and intermediate is 10%, also with significant improvement in efficiency. 【Conclusion】 The detection of properties of Fc fragment of IVIG is stable and efficient, it can be used for properties of Fc fragment of IVIG.