THERMAL ACTIVATION OF PEROXIDASE FROM TOBACCO LEAF MESOPHYLL CELL WALLS

Cell wall-bound peroxidase isolated from tobacco leaf mesophll cell walls was found to consist of two isoenzymes (P₁ and P₂). Each exists in the form of a single subunit with the same molecular weight (35 000) as determined by Sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Both isoenzymes exhibited maximum activities at 70°. P₁ increased to 265% and P₂ to 140% of the activities assayed at 27°; below this temperature the two isoenzymes had the same specific activity. On hydrolysis, P₁ showed a carbohydrate content of 26.22% when the monosaccharides were analyzed by gas liquid chromatography; P₂ gave 21.45%.     

Quality-of-Life in DDDR Pacing: Atrioventricular Synchrony or Rate Adaptation?

Al though differences in exercise performance have been observed between different rate adaptive modes, the relative impact of atrioventricular (AV) synchrony and rate adaptation on quality of life (QOL) have not been determined. Thirty-three patients with either sinoatrial disease (18) or complete atrioventricular (AV) block (15) received DDDR pacemakers (16 minute ventilation sensing, 17 activity sensing). There were 11 males and 22 females, with a mean age of 66 ± 1 (range 39–78) years. The study was a double-blind, triple cross-over study comparing DDDR, DDD, and VVIR modes. At the end of each 8-week study period in each mode, QOL was assessed by a questionnaire evaluating patients' functional class (Classes I-IV), physical malaise inventory (41 items), illness perception (43 items), and overall QOL rating based on a 48 items measure covering different aspects of the patients' daily life adjustment. Two patients required early crossover from VVIR mode during the study. Patients experienced significantly fewer physi cal malaise such as temperature intolerance, dyspnea, and palpitations in the DDDR mode, compared with either DDD or VVIR pacing. DDDR pacing reduced the perception of illness in 5 of 43 items compared to VVIR pacing, and improved stamina and appetite compared to DDD pacing. The overall QOL score was 102 ± 2, 105 ± 2, 113 ± 2 in the DDDR, DDD, and VVIR modes, respectively, with a higher score indicating a poorer QOL (DDDR/DDD vs VVIR, P < 0.02). There was no change in functional classes between the three pacing modes. In conclusion, VVIR pacing has a lower QOL compared with DDD pacing, which can be further enhanced with rate augmentation.     

OESOPHAGEAL MICROBIAL FLORA IN CARCINOMA OF THE OESOPHAGUS

In 79 patients, with carcinoma of the oesophagus, oesophageal aspirates obtained at oesophagoscopy were cultured for aerobic and anaerobic organisms in an attempt to identify the microbial flora. The aspirate culture was correlated with the pathogens isolated when infective complications developed after operation. Bacteroides was isolated from the oesophagus in 39.2% of patients, streptococcus in 10.1% and coliform oganisms in 7.6%. No growth was obtained in 35.4% patients. Forty-one patients underwent oesophageal resection. Six of these had the complication of empyema thoracis in the postoperative period. Two patients had identical organisms isolated from the oesophagus and the empyema. B. melaninogenicus was cultured from the pleural fluid in two patients whose oesophageal aspirate culture yielded no growth. Six patients developed wound infection, all with anastomotic cutaneous fistula. There was no demonstrable relationship between the organisms isolated from the two sources. Prophylactic antibiotic administration should be directed against the bacteroides, since it is the most common organism isolated from within the oesophagus.     

DESIGN,SYNTHESIS AND 13 C- AND 1 H-N.M.R. INVESTIGATION OF A CYCLIC OCTAPEPTIDE TO MIMIC THE ZINC-BINDING SITE OF CARBOXYPEPTIDASE A

Considering the three-dimensional structure and the native Zn(II)-binding ligands of carboxypeptidase A followed by extensive model building, a cyclic octapeptide, cyclo-(Gly-L-Glu-Gly-Gly-L-His-Gly-L-His-Gly) was designed to mimic the Zn(II)-binding site of carboxypeptidase A. The cyclic octapeptide was prepared by high dilution technique from the corresponding linear octapeptide, N-Boc-Gly-γ-OBu^t-L-Glu-Gly-Gly-L-His-Gly-L-His-Gly-OBzlNO₂ via the azide method. The linear octapeptide was obtained by coupling of the two tetrapeptide fragments: N-Boc-Gly-γ-OBu^t-L-Glu-Gly-Gly-ONp and L-His-Gly-L-His-Gly-OBzlNO₂. The cyclic peptide was purified to homogeneity by the method of countercurrent distribution. The product obtained was both ninhydrin negative and Pauli's reagent positive. Further confirmation of this material was obtained by the proper amino acid ratio of its acid hydrolysate and by the proton magnetic resonance spectrum in which the various kinds of protons of this peptide were accounted for. A detailed ¹³C- and ¹H-n.m.r. investigation was undertaken to determine the Zn(II)-binding ligands of the cyclo-octapeptide. The assignments for all the resonances were attempted by pH titration, by employing homonuclear decoupling experiments and by synthesis of cyclo-octapeptide containing specifically deuterated amino acids cyclo-(Gly-L-Glu-Gly-d₂-Gly-d₂-L-His-Gly-L-His-Gly). Titration results of Zn(II) bound form of the cyclic peptide showed the presence of a 1:1 complex. Upon Zn(II)-binding, the proton resonances were shifted downfield, the largest change being that of the histidine residues and more particularly C(2)-H protons. The chemical shifts induced on glutamic acid residue were also observed for Glu CH₂γ. In the case of ¹³C resonances, the maximum change in chemical shift was observed in the histidine residues and especially in the imidazole ring upon complexation. Two methylenes of the glutamic acid residue showed a large change in chemical shift upon ligating to the metal ion. The most significant observation was the deshielding effect of the Glu COO^- group. The results demonstrate that Zn(II) binds both the imidazoles of the two histidine residues and the carboxyl side chain of the glutamic acid residue of the designed cyclic octapeptide.     

光谱核型分析联合微阵列比较基因组杂交诊断15号环状染色体综合征

目的 探讨联合应用光谱核型分析技术(spectral karyotyping,SKY)和微阵列比较基因组杂交技术(microarray-based comparative genomic hybridization,array-CGH)在诊断复杂疑难的环状染色体畸变中的价值.方法 对1例常规G显带染色体核型分析疑诊为46,XY,r(15)?的8岁男性生长发育迟缓患儿依次应用SKY及array-CGH技术常规进行制片杂交,并通过相应的显微摄像系统和计算机软件分析结果.结果 SKY技术明确了该患儿环状染色体来源于15号染色体,array-CGH技术明确患儿15q26.3末端存在约594 kb的缺失,染色体基因位点编码范围为99689349-100282878.结论 联合应用现代分子细胞遗传学技术可以从细胞到分子水平精确诊断复杂疑难的环状染色体病例,是常规染色体核型分析的有益补充,也有利于细胞遗传学向分子水平深入.     

胆囊癌专题系列文章述评

This is a series of four papers on "Gallbladder Cancer" written by the most famous hepatobiliary surgeons and oncologists in China. The titles of the papers are: ( 1 )" Preoperative management of patients with suspected gallbladder cancer"by CHEN Wei and LIANG Li-jian; (2)"Selection of surgical procedures for gallbladder cancer" by PENG Shu-you and HONG De-fei; (3) "Diagnosis and treatment of incidental gallbladder cancer" by JIANG Xiao-qing and QIU Ying-he; (4)"Comprehensive management of gallbladder cancer" by WANG Jian-dong and QUAN Zhi-wei. These papers emphasize on the following important points on gallbladder cancer: (1)Laparoscopic cholecystectomy is absolutely contraindicated when gallbladder cancer is known or suspected pre-operatively; patients with a pre-operative suspicion of gallbladder cancer should undergo laparotomy, exploration and cholecystectomy after proper pre-operative assessment; (2)With the exception of Tis and T1a tumors, all patients with resectable gallbladder cancer should receive radical cholecystectomy, and a R0 resection should be aimed at; ( 3 ) For patients whose cancer is an incidental finding on pathological review, a second radial resection should be carried out as soon as possible, except for Tis and T1a diseases;(4) There is very little role for chemotherapy and radiotherapy in the adjuvant or palliative treatment of gallbladder cancer; (5)Surgery is the only curative treatment for gallbladder cancer.     

Effect of Electrode Orientation on Lesion Sizes Produced by Irrigated Radiofrequency Ablation Catheters

Background: Irrigated radiofrequency (RF) ablation catheters may produce different lesion sizes dependent upon the electrode orientation to the tissue. This study examined the effect of irrigated electrode orientation on the lesion size and explores a potential mechanism for this effect.
Methods and Results: Lesions were created in isolated porcine myocardium using an open irrigation, closed irrigation, and nonirrigated RF catheter (all 3.5–4 mm tips). Lesions were created with the electrodes with all permutations of electrode orientation (vertical or horizontal), contact pressure (6 or 20 g), and saline superfusate flow (0.2 or 0.4 m/sec) over tissue interface. The effect of electrode irrigation without RF delivery on tissue temperature was assessed with intramyocardial temperature probes and infrared thermal imaging. For both irrigated catheters, the horizontal orientation produced 25–30% smaller lesion volumes than the vertical orientation despite equal or greater power deliveries. The horizontal orientation produced larger lesion volumes for the nonirrigated catheter. Higher superfusate flow rates were associated with decreased lesion volumes for the irrigated catheters but greater lesion volumes for the nonirrigated catheter. Catheter irrigation alone without RF delivery reduced intramyocardial temperatures up to 4.9°C and the horizontal orientation produced a 2-fold greater area of tissue cooling than the vertical orientation.
Conclusion: Horizontal electrode orientations reduce lesion volumes for irrigated RF catheters. This effect may be in part due to greater areas of active tissue cooling in the horizontal orientation.