Structure and conformation of linear peptides XII. Structure of tryptophanyl-glycyl-glycine dihydrate

The crystal structure of a tripeptide, tryptophanyl-glycyl-glycine dihydrate (C₁₅H₁₈N₄O₄·2H₂O, molecular weight = 354) has been determined. The crystals are orthorhombic, space group P2₁2₁2₁ with a= 7.875 (1) A,b= 9.009(1), c= 24.307(1) and Z = 4. The final R-index is 0.058 for 1488 reflections ((sin θ/λ≤ 0.6 A^?1) with I < 2σ(I). The molecule exists as a zwitterion, with terminal NH⁺₃ and COO^? groups. The peptide units are trans and nearly perpendicular to the plane of the carboxyl group. The backbone torsion angles are: ψ₁= 132.7°, ω₁= 174.2°, φ₂ 88.2°, ψ= 8.6°, ω₂ - 179.8°, φ= - 85.2°, ψ₃₁, = - 178.1°, ψ₃₂ 5.0°. For the sidechain of tryptophan, χ₁= - 171.6°, χ₂ 101.0°.     

The interaction of von Willebrand factor-A1 domain with collagen: mutation G1324S (type 2M von Willebrand disease) impairs the conformational change in A1 domain induced by collagen

BACKGROUND: It is established that the A3 domain in von Willebrand factor (VWF) contains the major collagen-binding site. However, there are conflicting reports describing the capacity of the A1 domain to interact with collagen types I and III. METHODS: In this study, we have used recombinant VWF-A1 polypeptides, as well as conformation-specific monoclonal antibodies (mAb), to analyze the A1-collagen interaction. RESULTS: The A1 domain bound to collagen with K(d) approximately 8.0 nm and this binding was blocked by the mAb 6G1, which blocks the interaction between ristocetin and VWF. In addition, collagen-bound A1 protein was able to support flow-dependent adhesion of platelets, demonstrating that the binding sites for collagen and glycoprotein (GP)Ib are different. Analysis with two conformation-specific mAb demonstrated that the structure of the A1 domain changed as a result of the binding to collagen. In contrast, the antibodies failed to detect conformational change in the G1324S mutant (type 2M von Willebrand disease). Thus, direct binding to collagen induces a change in the structural conformation within the VWF-A1 domain, and the G1324S substitution prevents this conformational change. CONCLUSION: This study has shown that the isolated A1 domain can simultaneously bind to collagen and platelet GPIb, supporting platelet adhesion under high-flow conditions. In addition, this study has used mAb to demonstrate that the binding of the isolated A1 domain or full-length VWF to collagen is accompanied by a conformational change in A1 domain.     

国产流行性感冒病毒裂解疫苗安全性及免疫效果观察

目的 评价国产流行性感冒(简称流感)病毒裂解疫苗的安全性和免疫效果.方法 选择6岁～、16岁～和>60岁3个年龄段人群共606名,每个年龄段人群按数字表法随机分入试验组(共213名)、对照组1(共195名)和对照组2(共198名),分别接种国产流感疫苗和2种进口流感疫苗,比较三组人群接种后副反应发牛率、抗体阳转率、保护率及几何平均滴度(GMT)增长倍数的差异.率的比较采用X2检验,几何平均滴度(GMT)增长倍数采用方差分析,P<0.05为差异有统计学意义.结果 试验组、对照组1、对照组2副反应发生率分别为3.76%(8/213)、4.10%(8/195)和3.54%(7/198),差异无统计学意义(X2=0.87,P=0.93).3个组H1N1、H3N2和B(亚)型血凝抑制(H1)抗体总阳转率分别为89.2%(190/213)、63.4%(135/213)、86.4%(184/213),88.7%(173/195)、61.5%(120/195)、87.2%(170/195),87.9%(174/198)、61.6%(122/198)、84.8%(168/198),各(亚)型抗体总阳转率差异无统计学意义(X2H1N1=0.94,PH1N1=0.63;X2H1N2=0.94,PH3N2=0.63;X2B=0.75,PB=0.69);3个组H1N1、H3N2及B型H1抗体平均增长倍数分别为10.7、7.3、8.4倍,10.5、6.3、8.3倍,10.2、7.1、8.8倍,各(亚)型H1抗体GMT增长倍数差异无统计学意义(FH1N1=0.35,PH1N1=0.70;FH3N2=2.22,PH3N2=0.11;FB=1.51,PB=0.35);3个组H1N1、H3N2及B型H1抗体保护率分别为100%(213/213)、70.0%(149/213)、95.3%(203/213),100%(195/195)、66.7%(130/195)、97.9%(191/195),99.5%(197/198)、66.2%(131/198)、96.5%(191/198),各(亚)型抗体保护率差异无统计学意义(X2H1N1=2.04,PH1N1=0.36;X2H3N2=0.74,PH3N2=0.69;X2B=0.42,PB=0.82).结论 国产裂解流感疫苗具有良好的安全性和免疫效果,可用于群体性接种.     

上海地区学生午餐营养及供应链状况研究

目的 了解上海地区学生午餐营养及供应链状况，为改善学生午餐营养状况，保障食品供应安全提供参考。方法 分析上海市学生午餐的营养、卫生、供应链、加工工艺等状况，采用定期抽检的方法，应用SNHAS对营养素、食品安全、感官进行综合评价。结果 各单位样本综合评价均合格，其中热量、蛋白质、脂肪均能达到或超过DRIs供给量的要求，但矿物质中Ca(仅为AI的32％)、视黄醇当量(仅为AI的57％)供给量较低。对供应链及卫生状况的分析表明，大型企业对各个环节控制严格，产品质量较好，但也存在保存时间过长等问题。结论 应进一步完善供应体系，建立高效的质量控制体系，推广营养配膳系统。     

A longitudinal study of age-associated memory impairment

An 8-year longitudinal study of elderly people has provided data concerning age-associated impairment (AAMI). In 1985 a random sample of 146 persons aged 65 years or more, living in their own homes, were assessed using the Guild Memory Test the Mini–Mental State Examination (MMSE) and other ratings. After excluding 21% of the sample because they scored less than 24 on the MMSE, and another 34% who fulfilled other exclusion criteria, some 48% of the remainder (22% of the total sample) clearly fulfilled NIMH criteria for AAMI and a further 36% (16% of the total sample) were recorded as forgetful. The NIMH criteria are appropriate for certain research purposes but not in assessing prevalence of memory disorders. Follow–up interviews were conducted after 2, 4, 6 and 8 years. The mortality rate and development of dementia among those fulfilling criteria for AAMI appeared similar to the other non-demented groups of subjects; the mortality rate of those with MMSE scores below 24 was significantly higher. Guild test results at 2-yearly intervals showed considerable changes; half of those scoring least well who were retested showed improvement.     

Sampling Patients Within and Across Health Care Providers: Multi-Stage Non-Nested Samples in Health Services Research

In order to better inform study design decisions when sampling patients within and across health care providers we develop a simulation-based approach for designing complex multi-stage samples. The approach explores the tradeoff between competing design goals such as precision of estimates, coverage of the target population and cost.We elicit a number of sensible candidate designs, evaluate these designs with respect to multiple sampling goals, investigate their tradeoffs, and identify the design that is the best compromise among all goals. This approach recognizes that, in the practice of sampling, precision of the estimates is not the only important goal, and that there are tradeoffs with coverage and cost that should be explicitly considered. One can easily add other goals. We construct a sample frame with all phase III clinical cancer treatment trials that are conducted by cooperative oncology groups of the National Cancer Institute from October 1, 1998 through December 31, 1999. Simulation results for our study suggest sampling a different number of trials and institutions than initially considered.Simulations of different study designs can uncover efficiency gains both in terms of improved precision of the estimates and in terms of improved coverage of the target population. Simulations enable us to explore the tradeoffs between competing sampling goals and to quantify these efficiency gains. This is true even for complex designs where the stages are not strictly nested in one another.     

ROOT ZX根管长度测量仪临床应用评价

目的 评价森田ROOT ZX根管长度测量仪临床应用价值.方法 用根管长度测量仪对108例根管进行根管测量,以此长度进行根管预备后,按测量长度插入牙胶尖摄X线牙片,计算出实际根管长度,求得测量准确率.结果 ROOT ZX测量准确率为92.6%.结论 ROOT ZX根管长度测量仪应用安全可靠、准确率高.     

Appendizitissonographie durch chirurgen — Erfahrungssache? Eine prospektive studie

A number of studies have shown that ultrasound has an advantage over physical examination in the diagnosis of acute appendicitis. Most of these studies were conducted by experts in the field of ultrasonography. In this study the influence of experience on the results of the sonography of actue appendicitis were evaluated. All 203 patients admitted to our unit between December 1990 and December 1992 were examined physically and sonographically by a team of surgeons consisting of one experienced sonographer and six inexperienced surgical trainees. Laparotomy was performed in 136 patients (46%). Appendicitis was demonstrated histologically in 119 cases (39.4%). Initial clinical findings were positive in 87 (28.8%). Sonography was positive in 119 patients (39.4%). The 163 patients not operated on demonstrated other pathology on ultrasound in 60 cases (19.9%). The rate of negative laparotomies amounted to 7.2% in our study. Sensitivity and specificity for the sonographic diagnosis were 92% and 95%, respectively. They were only 81% and 80% for physical examination. Overall accuracy was 92% for sonography. Sensitivity and specificity for the inexperienced surgeons were 87% and 93%, respectively, while the experienced surgeon reached values of 97% and 98%, respectively. The results of both groups are comparable with values in the literature, suggesting that ultrasound evaluation of appendicitis is not a diagnostic tool limited to a few experienced sonographers.     

精神发育迟滞儿童特殊教育三年随访

采用Ｈ－ＮＴＬＡ量表及婴儿～初中学生社会生活能力量表对太原市一个培智学校４４例精神发育迟滞患儿从１９８９～１９９２年连续４次测查智力，２次测查适应行为。结果显示３年间ＩＱ值变化无显著统计学意义，但视觉联想、概念关系、注意力及视觉识知能力有明显提高。患儿适应行为明显提高。经多元逐步回归分析显示，精神发育迟滞儿童智商的提高和母亲文化程度较高、患儿智力低下程度较轻、母亲职业为科技或行政管理人员、患儿初始教育年龄早呈正相关。     

多层螺旋CT与选择性冠状动脉造影对照研究及其临床应用

目的 评价冠状动脉多层螺旋CT血管造影(MSCTA)的临床应用价值。方法 25例患者均行冠状动脉MSCTA与选择性冠状动脉造影(SCA)，分析右冠状动脉、左冠状动脉主干、前降支和回旋支的通畅性，狭窄发生的部位和严重程度。将MSCTA与SCA结果对照，初步评价MSCTA的临床应用价值。结果 71支MSCTA显示无狭窄的冠状动脉支中，68支与SCA一致；29支显示狭窄的动脉支中，19支与SCA一致。其阴性预测值和阳性预测值分别为95．8％和65．5％；敏感度、特异度和准确度分别为86．4％、87．2％、87，0％。结论 MSCTA作为微创性检查，是评价冠状动脉病变和变异的重要的筛选手段。