Complete amino acid sequence of a subunit from rapeseed high molecular weight protein

A subunit (M, 15 600) from the high molecular weight protein from rapeseed was separated and isolated; its purity and homogeneity were ascertained. The subunit was cleaved with cyanogen bromide, trypsin, chymotrypsin, and Staphylococcus aureus V8 protease. The fragments were separated and isolated by polyacrylamide gel electrophoresis, gel filtration, column chromatography on Dowex 1 × 2, and paper electrophoresis. The amino acid compositions of the intact subunit and different fragments obtained from enzymatic and chemical cleavages were determined. The subunit and its fragments were sequenced by manual Edman method. The phenylthiohydantoin amino acids obtained after each step were identified by thin-layer chromatography and ultraviolet spectroscopy. The complete amino acid sequence of the subunit consisting of 125 amino acid residues has been established by the overlapping method.     

固定衬垫式和活动衬垫式全膝人工关节置换术后随访4．5年以上的对比性研究

背景：低接触应力旋转平台（活动衬垫式）和Insall Burstein-Ⅱ型（固定衬垫式）全膝人工关节假体各自独立的长期稳定性已有报道，但我们尚未见有关这两种假体的中长期随访及对比性研究。 方法：对32例双侧膝关节畸形和术前活动范围均相似的膝关节炎患者进行了前瞻性评估，患者同意一侧膝关节行活动衬垫全膝关节置换，另一侧膝关节行固定衬垫全膝关节置换。术后平均随访6年，使患者、医生和观测者的相关干扰降至最小，对两种假体进行对比分析，项目包括临床和X线片结果、生存率和并发症发生率。 结果：术后骨关节炎患者的功能评分和活动范围好于类风湿性关节炎患者。然而，对患者在膝关节协会评分、屈曲范围、主观表现或髌股并发症发生率等方面进行评估，没有发现活动衬垫式假体比固定衬垫式假体更好。X线片显示两者在假体排列上没有差异。两例使用活动衬垫式假体的膝关节需要再次手术，其中1例因衬垫脱位而需要早期翻修，另1例因深部感染而进行关节融合。 结论：我们发现中期随访患者的临床表现显示，活动衬垫式全膝关节置换术并不比固定衬垫式全膝人工关节置换术具有更多的优点。活动衬垫式假体发生假体脱位和半脱位的危险性应给予重视，在发生脱位后要早期进行翻修。 可信水平：治疗性研究，Ⅱ级，进一步可信度参见作者介绍。     

Influence of methylation of the histidine ring of [Sar1]angiotensin II on conformation and biological activity

[Sar¹His(1-Me)⁶]ANG II and [Sar¹His(3–Me)⁶]ANG II were synthesized by the solid-phase method and purified by reversed-phase HPLC. ¹H-NMR spectroscopy at 400 MHz demonstrated the presence of two major conformers for both peptides in DMSO, representing cis and trans isomers (ratio 1:3 and 1:4, respectively) due to restricted rotation at the His-Pro bond. The contractile activities of these peptides in the rat isolated uterus assay were <0.1 and 27% of that of ANG II, respectively. The bioactivities of these analogues were mirrored in their NMR spectra: the inactive analogue [Sar¹His(1-Me)⁶]ANG II showed perturbations of the Sar and His residues which were not present for [Sar¹His(3-Me)⁶]ANG II and the reference agonist [Sar¹] ANG II. The high activity of the analogue methylated at His N₃ suggests that an ionizable imidazole proton is not an absolute requirement for expression of biological activity by angotensin ligands, and that the imidazole group in the molecule may function in an ion dipole-based mechanism when an intramolecular proton transfer (charge relay) mechanism is not available. The biological activity of the ligand appears to depend on the degree of proton transfer from Tyr-OH to the imidazole acceptor, wherein complete (formal) proton transfer represents 100%, activity.     

COMPARISON BETWEEN PRESSURES MEASURED FROM THE PROXIMAL EXTERNAL JUGULAR VEIN AND A CENTRAL VEIN

Mean venous pressures were measured in 20 patients in whom acatheter, inserted via the external jugular vein, failed topass centrally. The catheter used had a rounded end and twoside holes. Pressures were measured with the patient's headin three different positions. The pressures were compared withthe central venous pressures measured from a catheter insertedthrough an antecubital vein (and confirmed to be placed centrally).In all patients the differences between the mean pressures fromthe two sites were all within 3 mm Hg and were not influencedby alteration in head position or the side of jugular. catheterization.     

TUTORIAL IN BIOSTATISTICS: BAYESIAN DATA MONITORING IN CLINICAL TRIALS

Many clinical trials organizations use regular interim canalyses to monitor the accruing results in large clinical trials. In disease areas such as cancer, where survival is usually a major outcome variable, ethical considerations may lead to a stipulated requirement for data monitoring of mortality. This monitoring has frequently taken the form of limiting interim analyses to be few in number, and specifying an extreme p-value of, for example, p<0⋅001 or p<0⋅01 as grounds for early termination of the trial. Group-sequential methods are also used. However, none of these approaches formally assesses the impact that the results of a clinical trial may have upon clinical practice. Thus a trial might be terminated early because of apparent treatment benefits, but might fail to influence sceptical clinicians to modify their future treatment policy. We discuss the application of Bayesian methods, including the use of uninformative, sceptical and enthusiastic priors, and demonstrate that the necessary calculations are both straightforward to perform and easy to interpret statistically and clinically. Methods are illustrated with interim analyses of a clinical trial in oesophageal cancer. © 1997 by John Wiley & Sons, Ltd.     

Acute Radiation Dermatitis Following Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia

Radiation exposure during fluoroscopic imaging poses potential risks to patients and physicians, especially during protracted cardiovascular or radiological interventional procedures. We describe a woman with refractory paroxysmal supraventricular tachycardia who underwent radiofrequency catheter ablation of the slow pathway involved in atrioventricular nodal reentrant tachycardia. The patient subsequently returned 4 weeks later with acute radiation dermatitis that was retrospectively attributed to a malfunction in the fluoroscopy unit that lacked a maximum current output cut-off switch. Using dose reconstruction studies and her estimated biological response, we determined that she received between 15 and 20 Gy (1 Gy = 100 rods) to the skin on her back during the procedure. The exposure will result in an increase in her lifelong risk of skin and lung cancer. This article underscores the potential for radiation-induced injury during lengthy therapeutic procedures using x-ray equipment.