Objective To preparing the reference material(RM) of lactate dehydrogenase(LD),we purification of LD from human erythrocyte(RBC)and studied its properties.Methods Using a modified procedure which including complete hemolysis of the RBC,hydroxyapatite treatment,(NH4)2 SO 4 Precipitation,CM- Sephadex C 50,Sephadex G100 and 5'- AMP- Sepharose 4B affinity chromatography.Results The purified LD has a sepecific activity of 163.0 kU/g protein.It is almost free of contaminating enzymes.Two corresponding bands were observed on both PAG plates stained for either protein or LD activity after electrophresis had been done.The apparent Michaelis constants were of 1.000 and 0.179 mmol/L for L-lactate and NAD and of 0.119 mmol/L 0.062 mmol/L for pyruvate and NADH respectively.Conclusion The final purified LD was found to be very similar to that in human serum in catalytic properties.It is intended to be a fundament to prepare a RM for the measurement of LD.

Objective To explore the feasibility and reasonable of low-dose scan on abdominal angiography in 64-slice spiral helical CT. Methods Phantom test: at 120 KV and from 200 mAs to 30 mAs at an interval of 10 mAs in each image acquisition, it was measured standard deviation (SD) of CT number, high contrast resolution and low contrast resolution, and then analyzed the relationship between the three parameters and the mAs values. Three mAs values were chosen to undertake clinical analysis.Clinical analysis: 90 randomly selected objects with abdominal angiography were divided into three groups,scanning with above three mAs values.Measurement of the SD value at the plain scan images was performed and the enhanced low-dose scan images were used post-processing with three-dimensional volume reconstruction (VR). The VR images were classified into three grades (excellent, moderate, bad) with the blind evaluation of three CT radiologists. The quality-correlation analysis was used between the standard deviation (SD) values of plain scan image and abdominal angiography VR image. Results According to the quality-correlation analysis between the standard deviation (SD) value of plain scan image and abdominal angiography VR image, the area under curve in receiver-operated characteristic (ROC) analysis was 0.921, 0.906 and 0.893 in each three group, respectively. Conclusions The low-dose scan of abdominal angiography is feasible. 80mAs can ensure better image quality. The enhanced scan probably can use 60mAs when the SD value is less than 5.78 in the plain scan; but when the SD value of plain scan is greater than 11.8, the enhanced scan is used best 100 mAs or higher.

Extracellular vesicles(EVs)are nano-sized bilayer vesicles that are shed or secreted by virtually every cell type.A variety of biomolecules,including proteins,lipids,coding and non-coding RNAs,and mitochondrial DNA,can be selectively encapsulated into EVs and delivered to nearby and distant recipient cells,leading to alterations in the recipient cells,suggesting that EVs play an important role in intercellular communication.EVs play effective roles in physiology and pathology and could be used as diagnostic and therapeutic tools.At present,although the mechanisms of exosome biogenesis and secretion in donor cells are well understood,the molecular mechanism of EV recognition and uptake by recipient cells is still unclear.This review summarizes the current understanding of the molecular mechanisms of EVs'biological journey in recipient cells,from recognition to uptake and cargo release.Furthermore,we highlight how EVs escape endolysosomal degradation after uptake and thus release cargo,which is crucial for studies applying EVs as drug-targeted delivery vehicles.Knowledge of the cellular processes that govern EV uptake is important to shed light on the functions of EVs as well as on related clinical applications.