Antigenic relationships on the diphtheria toxin molecule: antitoxin versus antitoxoid.

We used the mouse to produce antisera to native diphtheria toxin and diphtheria toxoid. With these antisera it was possible to distinguish between toxin and toxoid. By gel diffusion analysis, antitoxin detected antigenic determinants on toxin which were not available on toxoid, indicating that some determinants had been lost or altered by formalin treatment. Antitoxoid, on the other hand, showed reactions of identity between toxin and toxoid in gel diffusion. The toxin neutralization titers measured in tissue culture were the same for both antisera. Only antitoxin neutralized the adenosine 5'-diphosphate ribosyl-transferase activity of fragment A, but suprisingly both antisera had significant anti-fragment A titers when tested by passive hemagglutination. It is suggested that some of the anti-fragment A activity in antitoxin affects the enzyme active site, whereas that in antitoxoid does not, implying the existence of a least two independent antigenic regions on fragment A.     

Azithromycin retards Pseudomonas aeruginosa biofilm formation

Using a flow cell biofilm model, we showed that a sub-MIC of azithromycin (AZM) can delay but not inhibit Pseudomonas aeruginosa biofilm formation and results in the development of a stable AZM resistance phenotype. Furthermore, mature biofilms were not affected by AZM.     

Paget disease of the anterior tibial tubercle

A study was done of 13 cases of biopsy-proved Paget disease in which the disease involved the anterior tibial tubercle with extension into the metaphysis and diaphysis, but without apparent involvement of the proximal tibial epiphysis. Case data were obtained from archives containing more than 350 cases of Paget disease. Age, sex, symptoms, serum alkaline phosphatase level, and histologic and radiographic appearance of the lesions were evaluated. Patients were young at clinical presentation, averaging 36 years of age. In five of six patients the serum alkaline phosphatase level was normal. The proximal extent of the disease was the anterior tibial tubercle rather than the proximal epiphysis. Radiographic patterns ranged from predominantly lytic to mixed lytic and blastic to predominantly blastic, and the lesion was marginated by a flame-shaped configuration. The radiographic appearance of Paget disease of the anterior tibial tubercle is characteristic and should be sufficient to suggest the diagnosis and preclude biopsy.     

Production of exoenzyme S during Pseudomonas aeruginosa infections of burned mice.

Antisera which distinguished between Pseudomonas aeruginosa exoenzyme S and toxin A neutralized the adenosine diphosphate ribosyl transferase activity of the homologous, but not the heterologous, enzyme. Skin extracts and sera from burned mice infected with the exoenzyme S-producing strain P. aeruginosa 388 contained adenosine diphosphate ribosyl transferase activity that was not found in skin extracts or sera from uninfected mice. On the basis of immunological reactivity and enzymatic properties, the adenosine diphosphate ribosyl transferase activity present in skin extracts and sera from P. aeruginosa 388-infected mice was identified as exoenzyme S. Active elongation factor 2 levels in tissues from strain 388-infected mice were normal at 24 h postinfection, indicating that strain 388 does not produce detectable amounts of toxin A in vivo. An unexpected finding in this investigation was the presence of exoenzyme S-inactivating activity in the sera from some nonimmunized animals.     

细胞角蛋白20检测在大肠癌微转移中的临床意义

近年来随着微转移在肿瘤研究领域中的广泛开展,人们开始研究大肠癌微转移,以期获得更准确,更早期的转移信息,为临床分期及预后判断、辅助治疗提供更多的依据．随着分子生物学、分子免疫学的迅速发展．使大肠癌的淋巴结、血液、骨髓及各脏器等用常规组织学难以诊断的癌细胞微转移灶的检测成为可能．细胞角蛋白20(cytokeratin-20,CK20)是新近发现的一种多肽,局限在胃肠上皮细胞,具有严格的组织特异性,几乎所有大肠癌都明显表达,优于其他标志物,尤其实用于检测大肠癌微转移．通过检测大肠癌患者淋巴结、血液、骨髓中CK20 mRNA的表达来诊断微转移,对指导临床大肠癌的分期、判断预后复发、指导治疗显示出较高的临床应用价值．微转移是一项独立的预后指标．其价值优于 Dukes分期和肿瘤分级．现综述细胞角蛋白20 检测在大肠癌微转移中的临床应用及意义研究进展．