外泌体提取及保存技术研究进展

外泌体是多种活细胞经过"内吞-融合-外排"等一系列过程主动向胞外分泌的纳米级双层膜结构小囊泡,广泛存在于血液和尿液等生物体液中.因其携带着多种蛋白质、核酸和脂质等生物活性分子,所以外泌体不仅在细胞间物质交换和信息传递中发挥重要作用,而且对疾病诊断、预后预测和治疗管理等均具有提示意义.外泌体的高效提取、分离和完整保存是研...     

原始生殖细胞发生的机制

生殖细胞的发生是发育和遗传的基础。在几乎所有哺乳动物中,原始生殖细胞（primordial germ cell,PGC）均由近端上胚层体细胞在周边细胞特定的信号诱导下特化而成。目前的研究已经发现一些与生殖细胞特化有关的信号分子和关键转录调控元件,以及特化后生殖细胞获得的与体细胞不同的生物特性。生殖细胞的特化是一个结合了体细胞发育程序的抑制、细胞多能性程序的启动和全基因组表观遗传重编程三个方面的动态的复杂过程。多能性干细胞（胚胎干细胞或诱导型多能干细胞）具有发育全能性,能分化为机体任何一种细胞类型,包括生殖细胞。利用多能性干细胞体外分化形成生殖细胞有助于深入系统地研究配子发生的调控机制,为干细胞在不育症治疗方面的应用带来新希望。     

绵羊红细胞的质量对静脉注射用人免疫球蛋白抗补体活性测定的影响

为了分析IVIG抗补体活性测定出现负值与绵羊红细胞质量的关系。采用CH50试验测定IVIG ACA时,在被检样品和其他试验条件相同的情况下,比较了被污染的和未污染的绵羊红细胞对IVIG抗补体活性测定的影响。结果显示,使用被污染的绵羊红细胞(作为试验材料时所得的)检测10份样品ACA(%)均为负值;使用未污染的绵羊红细胞未出现负值。提示被污染的绵羊红细胞干扰了抗补体活性测定,从而引起CH50试验结果出现偏差。     

Deep Sequencing Analysis of HBV Genotype Shift and Correlation with Antiviral Efficiency during Adefovir Dipivoxil Therapy

Background

Viral genotype shift in chronic hepatitis B (CHB) patients during antiviral therapy has been reported, but the underlying mechanism remains elusive.

Methods

38 CHB patients treated with ADV for one year were selected for studying genotype shift by both deep sequencing and Sanger sequencing method.

Results

Sanger sequencing method found that 7.9% patients showed mixed genotype before ADV therapy. In contrast, all 38 patients showed mixed genotype before ADV treatment by deep sequencing. 95.5% mixed genotype rate was also obtained from additional 200 treatment-naïve CHB patients. Of the 13 patients with genotype shift, the fraction of the minor genotype in 5 patients (38%) increased gradually during the course of ADV treatment. Furthermore, responses to ADV and HBeAg seroconversion were associated with the high rate of genotype shift, suggesting drug and immune pressure may be key factors to induce genotype shift. Interestingly, patients with genotype C had a significantly higher rate of genotype shift than genotype B. In genotype shift group, ADV treatment induced a marked enhancement of genotype B ratio accompanied by a reduction of genotype C ratio, suggesting genotype C may be more sensitive to ADV than genotype B. Moreover, patients with dominant genotype C may have a better therapeutic effect. Finally, genotype shifts was correlated with clinical improvement in terms of ALT.

Conclusions

Our findings provided a rational explanation for genotype shift among ADV-treated CHB patients. The genotype and genotype shift might be associated with antiviral efficiency.     

Kidney Stones in Primary Hyperoxaluria: New Lessons Learnt

To investigate potential differences in stone composition with regard to the type of Primary Hyperoxaluria (PH), and in relation to the patient’s medical therapy (treatment naïve patients versus those on preventive medication) we examined twelve kidney stones from ten PH I and six stones from four PH III patients. Unfortunately, no PH II stones were available for analysis. The study on this set of stones indicates a more diverse composition of PH stones than previously reported and a potential dynamic response of morphology and composition of calculi to treatment with crystallization inhibitors (citrate, magnesium) in PH I. Stones formed by PH I patients under treatment are more compact and consist predominantly of calcium-oxalate monohydrate (COM, whewellite), while calcium-oxalate dihydrate (COD, weddellite) is only rarely present. In contrast, the single stone available from a treatment naïve PH I patient as well as stones from PH III patients prior to and under treatment with alkali citrate contained a wide size range of aggregated COD crystals. No significant effects of the treatment were noted in PH III stones. In disagreement with findings from previous studies, stones from patients with primary hyperoxaluria did not exclusively consist of COM. Progressive replacement of COD by small COM crystals could be caused by prolonged stone growth and residence times in the urinary tract, eventually resulting in complete replacement of calcium-oxalate dihydrate by the monohydrate form. The noted difference to the naïve PH I stone may reflect a reduced growth rate in response to treatment. This pilot study highlights the importance of detailed stone diagnostics and could be of therapeutic relevance in calcium-oxalates urolithiasis, provided that the effects of treatment can be reproduced in subsequent larger studies.     

Effects of emodin and vitamin C on growth performance, biochemical parameters and two HSP70s mRNA expression of Wuchang bream (Megalobrama amblycephala Yih) under high temperature stress

In order to study the effects of dietary emodin, high-dose vitamin C (Vc) and their combination on growth of Wuchang bream (Megalobrama amblycephala Y.) and its resistance to high temperature stress, 1200 healthy Wuchang bream with initial body weight of 133.44 ± 2.11 g were randomly divided into four groups: a control group fed with basal diet (containing 50.3 mg/kg Vc) and three treated groups fed with basal diets supplemented with 60 mg/kg emodin, 700 mg/kg Vc, and the combination of 60 mg/kg emodin + 700 mg/kg Vc, respectively. After feeding for 60 days, the growth performance of Wuchang bream was measured. Then 25 fish per tank were exposed to heat stress of 34 °C. The biochemical parameters of blood and liver, and expression levels of liver two HSP70s mRNA before and after heat stress were determined and the cumulative mortality of each group under heat stress was counted. The results showed that before stress, compared with the control, the weight gain (WG) and specific growth rate (SGR), serum total protein (TP), lysozyme (LSZ), and alkaline phosphatase (ALP) levels, liver superoxide dismutase (SOD) activity and expression level of HSP70 mRNA significantly increased in emodin and Vc groups while feed conversion rate (FCR), serum cortisol (COR), triglyceride (TG) and liver malondialdehyde (MDA) contents decreased (P < 0.05); liver catalase (CAT) activity also significantly increased in emodin group (P < 0.05). Although serum TP, LSZ, and liver HSP70 mRNA levels significantly increased and liver MDA level decreased in combination group (P < 0.05), no synergism was observed. After heat stress, compared with the control, the serum TP, LSZ, ALP levels, liver SOD, CAT activities, and expression levels of HSC70 and HSP70 mRNAs increased in emodin and Vc groups in varying degrees and serum COR, glucose, glutamic-pyruvic transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), TG and liver MDA levels decreased to some extent. Although these parameters had similar changing trend as above ones in combination group, it did not show any synergism either. Statistics showed that under heat stress, the cumulative mortalities of emodin and Vc groups, except at 6 h in emodin group, were significantly lower than that of the control (P < 0.05) while the difference between the combination and control groups was not significant (P > 0.05). Thus, the basal diet supplemented with 60 mg/kg emodin or 700 mg/kg Vc could promote the growth of Wuchang bream, reduce FCR, increase non-specific immunity of fish, antioxidant capacity, and two HSP70s mRNA expression levels, and enhance resistance to heat stress in fish. However, the combination of emodin and high-dose Vc showed no better effect.     

青藏高原草地生态系统服务功能的季节动态变化

根据生态系统服务功能理论,利用RS和GIS技术,以生长季为时间单元,对青藏高原研究区草地生态系统服务功能的动态过程进行有效分析和评价.结果表明:提供生物量功能呈现上升—下降—上升的过程,在5月和9月分别出现两个高峰值,其中5月为最高峰值.影响该功能的主要因子为光合有效辐射值、水分状况和地下生物量的季节变化;碳蓄积和氧释放功能呈现上升—下降—上升的弱“N”型趋势;土壤养分保持功能也呈弱“N”型趋势,并在5月份出现最高值;草地保持土壤水分的功能在生长季内呈较强的阶段性变化,这主要与草地植物生长的季节性耗水变化规律有关.     

青霉菌立体选择性环氧化顺丙烯磷酸产生磷霉素

由土壤中分离出一株青霉 (Penicilliumsp .) ,编号F5,能选择性的将顺丙烯磷酸环氧化为磷霉素 ,在pH7 5、2 8℃、2 80r min条件下培养 6d ,底物浓度 0 3%时 ,产物浓度达 2 2mg mL ,产率 41 % ;底物浓度 0 6%时产率 8%。转化产物经磷霉素敏感菌生物检测 ,TLC检测 ,并与标准品比较 ,确证为磷霉素。