The density and distribution of microvessels may play major roles in the determination of the initial rate of contrast medium uptake and the heterogeneity of tumor enhancement.

A 57 kDa protein (p57) was obtained during the study on phosphatidylinositol-specific phospholipase C. Its cDNA was isolated from calf spleen and human leukemia cell line HL60 libraries and cloned. In the primary structures of p57, they have two unique amino acid sequence motifs, a WD repeat and a leucine zipper motif. Furthermore, p57 shared sequence similarity (40%) with coronin, an actin-binding protein responsible for chemotaxis, cell motility, and cytokinesis of Dictyostelium discoideum, which has only the WD repeat, p57 also showed an actinbinding activity and was mainly expressed in immune tissues. From these results, we conclude that p57 is a coronin-like novel actin-binding protein in mammalian cells but may also have a different function from coronin.

No abstract

Our purpose was to evaluate diffusion-weighted (DW) echo-planar MRI in differentiating between brain abscess and tumour. We examined two patients with surgically confirmed pyogenic brain abscess and 18 with metastatic brain tumours or high-grade glioma, using a 1.5 T system. The apparent diffusion coefficient (ADC) of each necrotic or solid contrast-enhancing lesion was measured with two different b values (20 and 1200 s/mm2). All capsule-stage brain abscesses (4 lesions) and zones of cerebritis (2 lesions) were identified on high-b-value DWI as markedly high-signal areas of decreased ADC (range, 0.58-0.70 [(10-3 mm2/s; mean, 0.63)]). All cystic or necrotic portions of brain tumours (14 lesions) were identified on high-b-value DWI as low-signal areas of increased ADC (range, 2.20-3.20 [(10-3 mm2/s; mean, 2.70)]). Solid, contrast-enhancing portions of brain tumours (19 lesions) were identified on high-b-value DWI as high-signal areas of sightly decreased or increased ADC (range, 0.77-1.29 [(10-3 mm2/s; mean, 0.94)]). Our preliminary results indicate that DW echo-planar MRI be used for distinguishing between brain abscess and tumour.

A diagnosis of low-grade fibromyxoid sarcoma (LGFMS) remains problematic because of its bland-looking histologic features that can be potentially confused with other benign or low-grade fibromyxoid lesions. Recent cytogenetic and molecular analyses have shown that most LGFMSs have a characteristic chromosomal abnormality, t(7;16)(q33;p11), resulting in the FUS-CREB3L2 fusion gene. However, such assays have only rarely been used to analyze formalin-fixed, paraffin-embedded tumor samples. In the present study, we conducted a reverse transcription-polymerase chain reaction assay to detect the FUS-CREB3L2 fusion transcripts using formalin-fixed, paraffin-embedded tumor tissue specimens from 16 LGFMSs including 3 cases with giant collagen rosettes. The primers were newly designed to specifically amplify most of the junctional regions of the FUS-CREB3L2 fusion gene transcripts previously reported. The FUS-CREB3L2 fusion gene transcripts were detected in 14/16 (88%) cases of LGFMS. A nucleotide sequence analysis of the PCR products revealed that different portions of the FUS exon 6 or 7 were fused with various sites of the CREB3L2 exon 5, resulting in 12 different nucleotide sequences. We also tested a primer set to detect the FUS-CREB3L1 fusion transcript, which is a rare variant of the gene fusion in LGFMS, although no PCR products were identified in any case. The FUS-CREB3L2 fusion transcripts were not detected in any of the 123 other soft-tissue tumors, including desmoid-type fibromatoses, myxofibrosarcomas, soft-tissue perineuriomas, and congenital or adult fibrosarcomas. These data suggest that our reverse transcription-polymerase chain reaction assay is a reliable method to detect FUS-CREB3L2, which can thus help in accurately diagnosing LGFMS.

Mycobacterium tuberculosis evades the innate antimicrobial defenses of macrophages by inhibiting the maturation of its phagosome to a bactericidal phagolysosome. Despite intense studies of the mycobacterial phagosome, the mechanism of mycobacterial persistence dependent on prolonged phagosomal retention of the coat protein coronin-1 is still unclear. The present study demonstrated that several mycobacterial proteins traffic intracellularly in M. bovis BCG-infected cells and that one of them, with an apparent subunit size of Mr 50,000, actively retains coronin-1 on the phagosomal membrane. This protein was initially termed coronin-interacting protein (CIP)50 and was shown to be also expressed by M. tuberculosis but not by the non-pathogenic species M. smegmatis. Cell-free system experiments using a GST-coronin-1 construct showed that binding of CIP50 to coronin-1 required cholesterol. Thereafter, mass spectrometry sequencing identified mycobacterial lipoamide dehydrogenase C (LpdC) as a coronin-1 binding protein. M. smegmatis over-expressing Mtb LpdC protein acquired the capacity to maintain coronin-1 on the phagosomal membrane and this prolonged its survival within the macrophage. Importantly, IFNγ-induced phagolysosome fusion in cells infected with BCG resulted in the dissociation of the LpdC-coronin-1 complex by a mechanism dependent, at least in part, on IFNγ-induced LRG-47 expression. These findings provide further support for the relevance of the LpdC-coronin-1 interaction in phagosome maturation arrest.

Amyloid beta peptide (Abeta) is a physiological peptide that is constantly catabolized in the brain. We previously demonstrated that an endopeptidase sensitive to phosphoramidon and thiorphan conducts the initial rate-limiting proteolysis of Abeta in vivo, but the exact molecular identity of the peptidase(s) has remained unknown because of the molecular redundancy of such activity. We analyzed the brain-derived enzyme by means of immuno-depletion and gene disruption, and demonstrate here that neprilysin accounts for the majority of the Abeta-degrading activity. Furthermore, kinetic analysis, giving a K(m) value of 2.8 +/- 0.76 microM, indicated that Abeta(1-42) is a relevant substrate for neprilysin.

Early peripheral enhancement with centripetal progression appears to be fairly specific for carcinomas, whereas early enhancement with minimal or no centripetal progression, although more common in malignant tumors, may be seen in some benign lesions as well.