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1.
目的确定源于纤维单胞菌(Cellulomonose sp.)的聚阿拉伯糖内切酶的性质。方法SDS—PAGE和凝胶层析测定相对分子质量,离子交换层析估计等电点,TLC法测定酶活力,Lineweare—Burk双倒数做图法测定酶促反应动力学特性。结果相对分子质量为45kD,等电点约为6.0,酶促反应动力学符合Michaelis—Menten动力学规律,在37℃反应条件下,米氏常数Km为2.5mg/ml,最大反应速率Vmax为0.083μmol/L·min,最适pH为8.0,pH6.0~9.0时较稳定。最适温度为40℃,在40℃以下较稳定,超过50℃时酶活力开始下降。结论确定了一种聚阿拉伯糖内切酶的性质。 相似文献
2.
目的:从fao基因转化的E.coli BL21/DE3菌分离纯化重组酿酒酵母长链脂肪酸醇氧化酶,并对其理化性质进行研究。方法:应用硫酸铵分级沉淀、phenyl-sepharose HR5/5层析等方法分离纯化长链脂肪酸醇氧化酶,应用SDS-PAGE电泳测定其相对分子量,并对其Km、酸碱稳定性及其底物特异性进行分析。结果:应用上述分离方法得到电泳呈单一条带的酶蛋白,相对分子量大约为64000,得率为17.6%以上;该酶对十二烷醇的Km在2.5和3.0μmol/L之间,最适pH值为8.5,在pH7.0环境中,酶活性为pH8.5时的60%;对十二烷醇催化的相对活性较其它一些长链的二醇和脂肪酸醇为高。结论:从fao基因转化的E.coli BL21/DE3菌分离出重组酿酒酵母长链脂肪酸醇氧化酶,该酶为碱性酶,其最适底物为十二烷醇,但也可氧化一些长链的二醇和脂肪酸醇。 相似文献
3.
用粘度测定法和还原糖测定法,研究了中性蛋白酶非专一性降解壳聚过程中温度,pH值,反应时间,酶浓度,底物浓度,金属离子及壳聚糖的脱乙酰度对中性蛋白酶降解壳聚糖反应速度的影响,确定了以壳聚糖为底物的中性蛋白酶的一些催化特性:最适温度为50℃;最适pH值为6.0;米氏常数Km值为1.1×10^-2g/mL;一定浓度的Cu62+,Ba^2+,Mn^2+抑制该酶的活性; 相似文献
4.
目的研究一种国产谷氨酸脱氢酶的热稳定性、酸碱耐受性、最适温度、最适pH和动力学参数等性质。方法以α-酮戊二酸、铵离子及还原型辅酶I(NADH)为底物,在谷氨酸脱氢酶催化作用下,转变为谷氨酸和氧化型辅酶I(NAD),利用NADH在340nm处有吸收峰,监测其反应速率(-△A Jmin),计算谷氨酸脱氢酶的活力单位,采用Linewaeaver-Burk作图法(双倒数作图法)对谷氨酸脱氢酶的米氏常数进行测定。结果谷氨酸脱氢酶于50℃保温20min保留活力约为87.5%,而在60℃保温20min后残存活力为54%;最适反应温度为45℃;最适反应pH为7.5;在pH为5~10范围内酸碱耐受性较好,25℃放置20h残留活力为90%以上。结论动力学研究表明该酶与国外知名厂家产品相差不大。 相似文献
5.
目的 将血管紧张素转换酶(ACE)固定化并测定其动力学性质。方法 以甲壳糖为载体,碳二亚胺(EDC)为交联剂,与分离纯化的ACE混合,使ACE固定化;并以马尿酰甘氯酰甘氨酸(HCG)为底物,分别测定了其游离酶和固定化酶的动力学性质。结果 固定化酶活力110u/g湿重,固定化率为22%,与游离酶比较,固定化酶稳定且具良好的耐热性,在50—80℃固定化酶较游离酶稳定。在pH7.1的底物缓冲体系中,37℃,游离酶Km=0.026mol/L;在间歇振摇下固定化酶的表现Km=0.040mol/L。游离酶最适pH为、8.0固定化酶最适pH为9.0。结论 用甲壳糖固定ACE方法简便可行,且固定后的甲壳糖性能稳定,有广阔的应用前景。 相似文献
6.
目的 研究棘托竹荪菌盖胞外β-葡萄糖苷酶酶学特性. 方法 将棘托竹荪菌盖胞外酶冻干粉以缓冲液进行溶解,经透析、离心后,以DNS为显色剂,以水杨苷为底物,采用分光光度法,对β-葡萄糖苷酶的主要酶学特性和不同抑制剂、激活剂对酶活性的影响进行研究. 结果 β-葡萄糖苷酶的最适反应pH为4.0,最适反应温度为65℃;Hg2+、Cu2+对酶起抑制作用,Fe2+、Zn2对酶具有激活作用;棘托竹荪菌盖胞外β-葡萄糖苷酶对水杨苷的米氏常数(Km)为1.320×10-2 mol/L,最大反应速度Vmax为0.143 7μmol/min,比活力为2.874 U/mg. 结论棘托竹荪菌盖胞外β-葡萄糖苷酶偏好酸性环境,其温度适应范围较宽,温度升高可提升酶催化活性,但影响酶的稳定性. 相似文献
7.
目的研究呼吸道合胞病毒(respiratory syncytial virus,RSV)G蛋白基因工程菌的发酵工艺。方法通过摇瓶培养初步确定工程菌的最适生长条件和表达条件,以此为基础在发酵罐中比较、筛选影响菌体生长和目的蛋白表达率的各种条件,对发酵丁艺进行改良优化。结果确定了RSVG蛋白基因工程菌发酵罐培养的各项条件的最佳组合:在LB+葡萄糖的培养基中,搅拌速度为200r/min,培养温度为37℃,pH值为7.0,诱导时温度为25℃,IPTG浓度为0.01mmol/L,优化后T程菌菌体的产量可以达到39.20g/L,目的蛋白表达率平均为18.1%。结论建立了稳定高效的重组RSVGT程菌发酵工艺。 相似文献
8.
目的:研究酶促反应的动力学参数,为新药设计提供依据。方法:采用HPLC方法测定酶促反应的动力学参数及蒜酶的最适pH和最适温度。结果:蒜酶以蒜氮酸为底物,最大反应速度Vmax=27.9 μnml·min-1·mg-1,米氏常数Km=3.6 mmol/L,其最适pH为6.6,最适温度为35℃。结论:酶促反应的动力学参数为蒜酶寻求有利的反应条件、更大限度地提高酶反应的效率提供了参考数据。 相似文献
9.
目的:在克隆表达肺炎链球菌HMG-CoA合成酶(HMGS)的基础上,对HMGS进行动力学研究。方法:采用紫外分光光度法,以乙酰-CoA作为底物,检测乙酰乙酰-CoA在300 nm处吸收值的变化。结果:肺炎链球菌HMGS的最适pH 9.75、最适温度37℃、最适MgCl2浓度为10 mol/L,粗酶提取物的比活为0.76μmol/min·mg^-1,分离纯化后的比活为3.24μmol/min·mg^-1,比活提高4.26倍。结论:在37℃、pH 9.755、mol/L MgCl2的最适反应条件下,肺炎链球菌HMGS的Vmax和Km值分别为4.69μmol/min·mg^-1和213μmol。 相似文献
10.
用酵母的丙酮酸脱羧酶粗提物催化苯甲醛合成L-苯基乙基甲醇,后者为合成L-麻黄素的前体。酶转化反应的最佳温度为10℃,PH6.8,时间为5-6h,酶用量7u/ml,乙醇2.0mol/L,苯甲醛150-180mmol/L,丙酮酸150-200mmol/L,转化液中L-PAC浓度可达140mmol/L。 相似文献
11.
Objective: To evaluatel the value of D-dimers in patients with acute aortic dissection (AAD). Methods: This study consisted of 16 patients with AAD and 27 non-AAD patients. Serum D-dimets were measured by Sta-Liatest D-DI immunoturbidimetric assay. Results: D-dimer level was higher (P < 0.001) in patients with AAD(7.91 ± 5.52 μg/ml) than that in non- AAD group(1.57±1.24 μg/ml). D-dimer was positive (>0.4 μg/ml) in all patients with AAD and in 10 control group patients (37%). Among patients with acute AAD, D-dimers tended to be higher in Stanford A than in Stanford B (8.67 ± 4.31 μg/ml vs. 3.24±1.27 μg/ml, P <0.01). D-dimer values tended to be higher in more extended disease(3.84 ± 1.65 μg/ml, 8.57 ± 3.58 μg/ml and 11.87 ± 5.69 μg/ml in thoracic aorta, thoracic and abdominal aorta, thoracic and abdominal aorta and iliacal arteries, respectively, P < 0.05 for both 8.57 ± 3.58 and 11.87 ± 5.69 vs. 3.84 ± 1.65 ). Including the control group into the analysis, we found a sensitivity of 100%, a negative predictive value of 100%, and a specificity of 66% and a positive predictive value of 64% for D-dimer in diagnosis of AAD in our patients with suspected AAD. Conclusion: D-dimer was elevated in patients with AAD. A negative D-dimer test result could be useful in excluding AAD. 相似文献
12.
Jiageng Zhu Jun Li Ruipeng Ji Jianghao Su Mingshun Shen Zhigang Cao 《南京医科大学学报(自然科学版)》2007,21(2):125-128
Objective: To set up a simple and reliable rat model of combined liver-kidney transplantation. Methods: SD rats served as both donors and recipients. 4℃ sodium lactate Ringer's was infused from portal veins to donated livers,and from abdominal aorta to donated kidneys, respectively. Anastomosis of the portal vein and the inferior vena cava (IVC) inferior to the right kidney between the graft and the recipient was performed by a double cuff method, then the superior hepatic vena cava with suture. A patch of donated renal artery was anastomosed to the recipient abdominal aorta. The urethra and bile duct were reconstructed with a simple inside bracket. Results: Among 65 cases of combined liver-kidney transplantation, the success rate in the late 40 cases was 77.5%. The function of the grafted liver and kidney remained normal. Conclusion: This rat model of combined liver-kidney transplantation can be established in common laboratory conditions with high success rate and meet the needs of renal transplantation experiment. 相似文献
13.
Tao Ye * Zhi-quan Liu Jian-jun Mu Xi-han Fu Jun Yang Bao-lin Gao and Xiao-hong Zhang Department of Cardiology First Hospital of Xi'an Jiaotong University Xi'an Hanzhong Cardiovascular Institute Hanzhong 《中国医学科学杂志(英文版)》2004,19(4):248-251
Objective To observe blood pressure change with age in salt-sensitive teenagers whose salt sensitivity were determined by repeated testing.Methods Salt sensitivity was determined through intravenous infusion of normal saline combined with volume-depletion by oral diuretic furosemide in 55 teenagers. After five years, salt sensitivity was re-examined and subject blood pressure was followed up. Blood pressure changes in salt-sensitive teenagers were compared to that of non-salt sensitive teenagers over five years.Results After 5 years, the repetition rate of salt sensitivity determined by intravenous saline loading is 92.7%. In teenagers with salt sensitivity on the baseline, both the systolic blood pressure increments and increment rates were much higher than non-salt sensitive teenagers (12.7±12.1 mmHg vs. 2.8±5.2 mmHg, P< 0.01; 12.2%± 12.0% vs. 2.5% ±4.4%, P< 0.001,respectively). There was a similar trend for diastolic blood pressure (8.4 ± 6.4 mmHg vs. 3.7 ± 6.4 mmHg, P = 0.052; 13.2% ±10.6 % vs. 6.8%± 10.1%, P = 0.053, respectively).Conclusions Salt sensitivity determined by intravenous saline loading showed good reproducibility. Blood pressure increments with age were much higher in salt-sensitive teenagers than non-salt sensitive teenagers, especially in terms of systolic blood pressure. 相似文献
14.
目的:评价使用安心颗粒对急诊经皮冠状动脉介入术(PPCI)术后生活质量的影响.方法:将160例接受PPCI的急性ST段抬高型心肌梗死患者随机分为安心颗粒组(术前顿服安心颗粒8.8g,术后安心颗粒4.4 g/次,每日2次)和对照组(仅接受基础药物治疗).所有患者均服用阿司匹林、氯吡格雷和阿托伐他汀.分别在入院时、出院前1d、出院后180 d时,应用心肌梗死多维度量表(MIDAS)、中文版SF-36评价量表对患者生活质量评分.并观察术后30 d以内的出血并发症、血小板减少症发生情况.结果:入院时和出院前1d,两组患者的心肌梗死MIDAS、SF-36量表评分比较无差异(P>0.05);出院后180 d时,与对照组比较,安心颗粒组MIDAS、SF-36评分明显减低(P<0.05);组内与入院时比较,两组出院前1d、出院后180 d时,MIDAS、SF-36评分均降低(P<0.05).两组患者在随访期间均无大量出血、少量出血、重度和极重度血小板减少症发生,安心颗粒组有4例、对照组有7例发生不明显出血(P>0.05).两组发生轻度血小板减少症的患者数比较无差异(P>0.05).结论:PPCI使用安心颗粒,能改善急性ST段抬高型心肌梗死患者的生活质量,且不增加出血风险. 相似文献
15.
Jingming Zhu Ningning Hui Xiuhong Jiang Huaxing Zhang Chengzhang Fu 《南京医科大学学报(自然科学版)》2007,21(6):386-389
Objective:To investigate the influences of urapidil and nicardipine on rabbit sinus function,atrio-ventricular node function and hemodynamics.Methods:Thirty-two Angora's rabbits were selected and randomly divided into four groups.U1 group:urapidil 0.25 mg/kg;U2 group:urapidil 0.5 mg/kg;N1 group:nicardipine 10 μg/kg;N2 group:nicardipine 20 μg/kg.All these medicine were administrated within 30 seconds.Measurements were taken before and after the administration of urapidil or nicardipine for the following data:mean blood pressure(MAP),heart rate(HR),sino-atrial conduction time(SACT),maximal sinoatrial recovery time(SNRTmax)corrected sinus node recovery time(CSNRT),index of sinus node recovery time(SNRTI),Wenckebach A-V conduction frequency (WB),and P-R interval.Results:Significant MAP and HR changes were identified in all of the four groups before and after administration of both urapidil and nicardipine.No significant changes could be found in the rest of the parameters.Intergroup analysis showed that SACT and CSNRT of N1 and N2 groups were shorter than those of the U2 group(P<0.01);the MAP decreased(P<0.01)and the HR increased drastically(P<0.01).Conclusions:Neither urapidil(0.25 mg/kg,0.5 mg/kg)nor nicardipine(10μg/kg,20μg/kg)has any significant influence on rabbit sinus function or rabbit atrio-ventricular node function.Nicardipine could be a better choice than urapidil for parafunctional sinus node patients. 相似文献
16.
Objective:To investigate the gene expression of osteoprotegerin(OPG) and osteoclast differentiation factor(ODF) in the bone tissue of patients with hip fracture due to osteoporosis. Methods:OPGmRNA and ODFmRNA in the bone tissue in 50 cases of osteoporosis sufferers(over 50 years old) with hip fracture(Observer Group) and 30 cases of hip facture sufferers with no osteoporosis(Control group) were analyzed with the Semi-Quantitative RT-PCR method. Results:The mRNA expressed of ODF, OPG were both high in the patients with hip fracture. In the control group, the expression of OPG mRNA was observed, while the expression of ODF mRNA was very slight. Conclusion:Aged patients contained all signals including OPG, ODF that are essential for inducing osteoclastogenesis and promoting bone resorption. 相似文献
17.
The clinicopathological and immuohistochemical analysis of solid-pseudopapillary tumor of the pancreas: report of 9 cases 总被引:1,自引:0,他引:1
Shaoqin Chen Shengquan Zou Qibao Dai Peisheng Huang Weihua Cai Hong Li 《南京医科大学学报(自然科学版)》2007,21(6):398-401
Objective:To investigate the clinical features, pathological characteristics and immunophenotype of solid-pseudopapillary tumor of the pancreas(SPTP). Methods:Nine surgically treated cases of SPTP were retrospectively reviewed. Hematoxylin and Eosin(HE) staining and immunohistochemical staining were used to analyze all cases, and the general clinical data was collected. Results:Six patients were asymptomatic except for a palpable mass. Two patients complained of vague-epigastric pain. One patient appeared jaundice. The tumor was encapsulated and solid tissues alternately with cystic tissues. Histologically, the histological structure of solid portion was pseudopapillary with a fibrovascular core. Tumor cells were uniform and medium-sized which were arranged in sheets ets or nests or pseudopapillary patterns. Immunohistochemical studies demonstrated that SPTP proved positive in vimentin(9/9 cases), AAT(9/9 cases), NSE(9/9 cases), ACT(7/9 cases), CK20(2/9 cases), CgA(1/9 cases), S-100(3/gcases), PR(4/gcases), Syn(3/9 cases) and CD56(5/9cases), negative in CEA and ER. Conclusion:SPTP is a tumor predominantly occurring in young women frequently without special symptoms. This tumor has various characteristical histological patterns with different immunophenotype. 相似文献
18.
Scientific principles and rigorous processes should be followed in developing clinical guidelines for therapeutic interventions of integrative medicine
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A clinical guideline for the therapeutic interventions of integrative medicine may be defined as a written document which states a series of recommendations on therapeutic interventions of integrative medicine for a special disease or condition. The guideline may provide assistance to medical professionals in making clinical decisions aimed at improving the clinical outcome of patients and reducing the costs of medical care(~'4~. Recommendations issued by a guideline should be based on the best available evidence in both Western and Chinese medicine. For fulfilling this purpose, the development of clinical guidelines for therapeutic interventions in the field of integrative medicine should follow scientific principles and undergo a rigorous processes. 相似文献
19.
Objective:To probe into the influence of changes of ovarian hormones on the pathogenesis of the specific sub-type premenstrual syndrome(PMS)and reveal partial microcosmic mechanisms of adverse flow of liver-qi.Methods:Estradiol(E2)and progesterone(P)levels in serum were determined at different phases of menstrual cycle by radioimmunoassay.Results:In the group of PMS with adverse flow of liver-qi.the secretive peak value Of E2 and P at the follicular phase significantly decreased,and the secretive peak value at the luteal phase did not come into being.Conclusions:Low E2 and P secretive peak at the follicular phase and absence of secretive peak at the luteal phase is one of the microcosmic mechanisms of PMS with adverse flow of liver-qi.One of the pathophysiologic mechanisms of specific sub-type PMS is probably the continuous low level of E2and P. 相似文献
20.
Real-time three-dimensional echocardiography (RT3DE)is a new ultrasound technique that enables dynamic threedimensional visualization and quantification of the heart in real time. Investigation of feasibility and methodology of RT3DE in determining left ventricular (LV) and right ventricular (RV) volumes, RT3DE was performed in 35 normal adults using Philips SONOS 7500 system with a 2-4 MHz matrix array transducer. The 60°×60° "pyramid" volume database was obtained and analyzed on a TomTec echo workstation. Both LV and RV volumes were calculated with four 3DE methods (i.e. apical 2, 4, 8, and 16-plane) through manually tracing ventricular endocardial borders in end diastole and end systole. Stroke volumes were then calculated. LV volume was also measured by 2DE Simpson's rule using GE VIVID 7 ultrasound machine. 相似文献