Data compression: effect on diagnostic accuracy in digital chest radiography

High-resolution digital images make up very large data sets that are relatively slow to transmit and expensive to store. Data compression techniques are being developed to address this problem, but significant image deterioration can occur at high compression ratios. In this study, the authors evaluated a form of adaptive block cosine transform coding, a new compression technique that allows considerable compression of digital radiographs with minimal degradation of image quality. To determine the effect of data compression on diagnostic accuracy, observer tests were performed with 60 digitized chest radiographs (2,048 x 2,048 matrix, 1,024 shades of gray) containing subtle examples of pneumothorax, interstitial infiltrate, nodules, and bone lesions. Radiographs with no compression, with 25:1 compression, and with 50:1 compression ratios were presented in randomized order to 12 radiologists. The results suggest that, with this compression scheme, compression ratios as high as 25:1 may be acceptable for primary diagnosis in chest radiology.     

全国细菌药敏试验的室间质量评价

目的：了解全国大中型医院细菌药敏试验（AST）状况，提高检测水平和质量。方法：定期向全国各参加评价实验室发放冻干标本，要求在规定时间内报告可疑感染的病原菌及其药敏结果，对回报结果给予数据统计、分析和评价。结果：2000年全国489个细菌室对常见耐药菌的检测正确率分别为：超广谱β－内酰胺酶63％（ESBLs)；苯唑西林敏感金黄色葡萄球菌（MSSA）74％；苯唑西林耐药凝固酶阴性葡萄球菌（MRSCoN)48％；对青霉素不敏感肺炎链球菌7％；氨基糖苷类高水平耐药肠球菌95％；产β－内酰胺酶流感嗜血杆菌正确率35％。结论：通过细菌药敏试验的室间质量评价反映出我国的细菌耐药性检测水平急待提高。     

以杯[4]芳烃衍生物为载体的钾离子选择电极的研究

目的：研制新的以杯[4]芳烃衍生物为载体的PVC膜钾离子选择电极。方法：以3种杯[4]芳烃衍生物为载体，癸二酸二辛酯或邻苯二甲酸二辛酯为增塑剂，四（4－氯）苯硼钾为离子定域体制得了PVC膜钾离子选择电极，测试了该类电极对钾离子的响应性能和对7种阳离子的选择性系数。结果：以5，11，17，23－四叔丁基－25，26，27，28－四[2-(乙氧基羰基）苄氧基]杯[4]芳烃为载体所制得的电极（电极Ⅰ）对钾离子有良好的能斯特响应，该电极的选择性系数优于电极Ⅱ和Ⅲ。分别用电极Ⅰ，Ⅱ，Ⅲ对青霉素V钾中的钾含量进行了测定，其结果均与原子吸收法基本一致。结论：所制得的上述电极是一类新的钾离子选择电极，有实用价值。     

沙土鼠短暂性脑缺血后海马损伤的形态学特征

本实验通过结扎沙土鼠双侧颈总动脉20分钟,再灌流7天内,动态观察背侧海马组织的形态学变化。光镜观察表明:海马各区对缺血的反应性不同,其中以 CA_1区锥体细胞对缺血最为敏感,并且 CA_1区神经元的损伤是迟发性的,再灌流4天后才出现大量神经元的坏死、消失,即“迟发性神经元死亡”(NDN)。电镜下发现:缺血再灌流早期(1～2天),CA_1区神经细胞质内有大量粗面内质网增多。本实验结果表明:短暂性脑缺血所致的海马损伤与脑组织其他区域神经元损伤不同。     

Mechanisms of protective action of radix Salviae miltiorrhizae (RSM) against experimental hepatic injury in rats]

The results indicated that RSM could significantly inhibit the lipid peroxidation of normal livers and cultured hepatocytes of rats, induce liver microsomal cytochrome P450 in normal rats, increase nucleic acids, proteins, urea and cerolloplasmin of damaged cultured hepatocytes of rats, relieve ultrastructural damage of cultured hepatocytes induced by CCl4. The pharmacological actions mentioned above should be considered as important mechanisms of RSM against liver injury.     

In-plane myocardial wall stress is not the primary determinant of coronary systolic flow impediment. A study in the isolated, perfused dog septum.

The hypothesis that ventricular in-plane tensile wall stresses are the major determinant of systolic coronary flow was investigated in this study. We measured coronary artery inflow in the maximally vasodilated bed of the isolated beating septum (n = 10) during two modes of contraction characterized by markedly different levels of developed in-plane stress. An increase in contractility was induced by changing from the control steady-state pacing state to a postextrasystolic potentiated state induced by a modified rapid pacing protocol. Over a range of increments of passive stretch, the systolic flow impediment versus the diastolic wall strain was described by an inverse linear relation. Despite the differences in developed in-plane wall stresses between the two modes of contraction (p less than 0.001), the slope and intercept of these relations in both the control and potentiated states were not different for the low versus high developed stress modes. The systolic flow impediment versus diastolic wall strain relation for the potentiated beats, compared with the control beats, was characterized by an increase in the intercept in both the low developed stress beats (p less than 0.05) and the high developed stress beats (p less than 0.05). These data indicate that the impediment to coronary flow during systole is not primarily determined by systolic myocardial in-plane tensile wall stresses but rather by the contractile state of the muscle.     

腹部CTA检查的质量保证

目的:探讨螺旋CT血管造影(Spiral CT angiography,SCTA)技术,以期提高SCTA造影的质量。材料与方法:采用Somatom Plus 4螺旋CT扫描系统对10例病人行腹部SCTA检查。扫描技术和造影剂参数按病变范围和性质而定,三维重建采用最大强度投影法(MIP)或表面阴影显示法(SSD)或弯曲平面重建法(CPR)。结果:SCTA检查技术能可靠地显示血管形态和病变,评价腹部肿瘤与邻近血管关系。结论:SCTA是无创伤性的血管成像术,在很大范围可替代创伤性的血管造影。     

Correlation between the intensity of cytomegalovirus infection and the amount of perivasculitis in aortic allografts

Abstract  We previously demonstrated that cytomegalovirus (CMV) infection enhanced perivascular inflammation in rat aortic allografts. In this study, we investigated the relationship between the CMV infection load and the magnitude of perivasculitis (chronic rejection) in aortic transplants. Rats received or-thotopic abdominal aortic grafts, different degrees of total body irradiation (TBI) for immunosuppres-sion and CMV inoculation. The spleens of the rats receiving 5 Gy of TBI contained more infectious virus and viral antigens than those of rats receiving 3 Gy of TBI or no TBI. Although the number of inflammatory cells infiltrating the perivascular area was decreased after TBI, CMV infection resulted in increased perivasculitis in rats that received 5 Gy of TBI as compared to non-infected animals. This virus-induced effect was characterized predominantly by an increased T-cell infiltration, including CD4 and CD8 T-cells. It is concluded that an enhanced systemic CMV infection during severe immunosuppressive therapy can accelerate the development of chronic rejection, which seems to be mediated mainly by T-cells.     

二丙酸倍氯米松联合酮替芬防治毛细支气管炎后婴幼儿哮喘的研究

目的　观察低剂量二丙酸倍氯米松和酮替芬联合应用能否降低毛细支气管炎后支气管哮喘患病率。方法　 5 6例毛细支气管炎患儿为治疗组 ,采用低剂量二丙酸倍氯米松局部吸入 ,口服酮替芬 ,疗程 6～ 9个月 ;32例毛细支气管炎患儿不用药作为对照组。临床随访≥ 1年 ,观察两组患儿哮喘发生率。同时检测治疗前、后患儿肺功能及骨密度。结果　完成随访 1年以上者 ,治疗组 5 2例中仅 3例 (5 77% )发生哮喘 ,而对照组 30例中有 14例 (4 6 6 7% )发生哮喘 ,两组比较有显著性差异 (P <0 0 1)。治疗组患儿肺功能与治疗前比较亦有显著性差异。两组骨密度检测治疗前、后比较无显著差异。结论　低剂量二丙酸倍氯米松局部吸入与酮替芬联合应用可降低毛细支气管炎后婴幼儿哮喘患病率     

胃肠内镜

内镜光学相干CT检测Barrett食管不典型增生的准确性：一项前瞻性、双盲研究；在无线食管pH监测期间有功能性胃灼热患更可能出现胸骨后不适；Barrett食管的冷冻消融术：一项先导性研究。