(1/542) Analysis of acute vascular damage after photodynamic therapy using benzoporphyrin derivative (BPD).
Benzoporphyrin derivative monoacid ring A (BPD-MA, verteporfin) is currently under investigation as a photosensitizer for photodynamic therapy (PDT). Since BPD exhibits rapid pharmacokinetics in plasma and tissues, we assessed damage to tumour and muscle microvasculature when light treatment for PDT was given at short times after injection of photosensitizer. Groups of rats with chondrosarcoma were given 2 mg kg(-1) of BPD intravenously 5 min to 180 min before light treatment of 150 J cm(-2) 690 nm. Vascular response was monitored using intravital microscopy and tumour cure was monitored by following regrowth over 42 days. For treatment at 5 or 30 min after BPD injection, blood flow stasis was limited to tumour microvasculature with lesser response in the surrounding normal microvasculature, indicating selective targeting for damage. No acute changes were observed in vessels when light was given 180 min after BPD injection. Tumour regression after light treatment occurred in all animals given PDT with BPD. Long-term tumour regression was greater in animals treated 5 min after BPD injection and least in animals given treatment 180 min after drug injection. The correlation between the timing for vascular damage and cure implies that blood flow stasis plays a significant role in PDT-induced tumour destruction. (+info)
(2/542) The EWS/TEC fusion protein encoded by the t(9;22) chromosomal translocation in human chondrosarcomas is a highly potent transcriptional activator.
The EWS/TEC gene fusion generated by the t(9;22) chromosomal translocation found in extraskeletal myxoid chondrosarcomas encodes a fusion protein containing the amino-terminal domain of the EWS protein fused to the whole coding sequence of the orphan nuclear receptor TEC. We have compared the DNA-binding and transcriptional activation properties of various TEC isoforms and the corresponding EWS/TEC fusion proteins. Band-shift experiments show that the full-length TEC receptor can efficiently bind the NGFI-B Response Element (NBRE), whereas an isoform lacking the entire carboxyl-terminal domain of the receptor binds much less efficiently the NBRE. Addition of the amino-terminal domain of EWS to either isoforms does not alter significantly their DNA-binding properties to the NBRE. Co-transfection experiments of COS cells and human chondrocytes indicate that whereas TEC moderately activates transcription from a NBRE-containing promoter, the corresponding EWS/TEC fusion protein is a highly potent transcriptional activator of the same promoter, being approximately 270-fold more active than the native receptor. EWS/TEC may thus exert its oncogenic potential in chrondrosarcomas by activating the transcription of target genes involved in cell proliferation. (+info)
(3/542) Sulphation heterogeneity in the trisaccharide (GalNAcSbeta1, 4GlcAbeta1,3GalNAcS) isolated from the non-reducing terminal of human aggrecan chondroitin sulphate.
We report here the isolation and sulphation isomer analyses of trisaccharides GalNAcS(beta1,4)GlcA(beta1,3)GalNAcS (in which S indicates sulphate) derived from the non-reducing termini of aggrecan chondroitin sulphate. Rat chondrosarcoma and human aggrecans were digested for 1 h at 37 degrees C with 30 micro-units of endo-chondroitinase ABC per microgram of chondroitin sulphate, and trisaccharides were isolated from the digests by ToyoPearl HW40S gel-filtration chromatography. Four trisaccharide species were identified; their sulphation isomer compositions, as determined by digestion with chondroitinase ACII and fluorescence-based ion-exchange HPLC, were GalNAc4Sbeta1,4GlcAbeta1,3GalNAc4S, GalNAc4Sbeta1,4GlcAbeta1,3GalNAc6S, GalNAc4,6Sbeta1,4GlcAbeta1, 3GalNAc4S and GalNAc4,6Sbeta1,4GlcAbeta1,3GalNAc6S. The abundances of such sequences in chondroitin sulphate on aggrecan from normal (foetal to 72 years of age) and from osteoarthritic human knee cartilages were also established. The results showed that non-reducing terminal GalNAc4S or GalNAc4,6S can be linked to either a 4-sulphated or a 6-sulphated disaccharide, suggesting that the sulphation of the last disaccharide might not have a direct effect on the specificity of chondroitin sulphate terminal GalNAc sulphotransferases. Furthermore, for each aggrecan preparation examined, the 4S-to-6S ratio of all chain interior disaccharides was equivalent to that in the last repeating disaccharides at the non-reducing terminus, suggesting that neither chondroitin 4-sulphotransferase nor chondroitin 6-sulphotransferase shows preferential activity near the chain terminus. (+info)
(4/542) EXT-mutation analysis and loss of heterozygosity in sporadic and hereditary osteochondromas and secondary chondrosarcomas.
Osteochondromas occur as sporadic solitary lesions or as multiple lesions, characterizing the hereditary multiple exostoses syndrome (EXT). Approximately 15% of all chondrosarcomas arise within the cartilaginous cap of an osteochondroma. EXT is genetically heterogeneous, and two genes, EXT1 and EXT2, located on 8q24 and 11p11-p12, respectively, have been cloned. It is still unclear whether osteochondroma is a developmental disorder or a true neoplasm. Furthermore, it is unclear whether inactivation of both alleles of an EXT gene, according to the tumor-suppressor model, is required for osteochondroma development, or whether a single EXT germline mutation acts in a dominant negative way. We therefore studied loss of heterozygosity and DNA ploidy in eight sporadic and six hereditary osteochondromas. EXT1- and EXT2-mutation analysis was performed in a total of 34 sporadic and hereditary osteochondromas and secondary peripheral chondrosarcomas. We demonstrated osteochondroma to be a true neoplasm, since aneuploidy was found in 4 of 10 osteochondromas. Furthermore, LOH was almost exclusively found at the EXT1 locus in 5 of 14 osteochondromas. Four novel constitutional cDNA alterations were detected in exon 1 of EXT1. Two patients with multiple osteochondromas demonstrated a germline mutation combined with loss of the remaining wild-type allele in three osteochondromas, indicating that, in cartilaginous cells of the growth plate, inactivation of both copies of the EXT1 gene is required for osteochondroma formation in hereditary cases. In contrast, no somatic EXT1 cDNA alterations were found in sporadic osteochondromas. No mutations were found in the EXT2 gene. (+info)
(5/542) Chemical modification and site-directed mutagenesis of conserved HXXH and PP-loop motif arginines and histidines in the murine bifunctional ATP sulfurylase/adenosine 5'-phosphosulfate kinase.
The sulfurylase domain of the mouse bifunctional enzyme ATP sulfurylase/adenosine 5'-phosphosulfate (APS) kinase contains HXXH and PP-loop motifs. To elucidate the functional importance of these motifs and of conserved arginines and histidines, chemical modification and site-directed mutagenesis studies were performed. Chemical modification of arginines and histidines with phenylglyoxal and diethyl pyrocarbonate, respectively, renders the enzyme inactive in sulfurylase, kinase, and overall assays. Data base searches and sequence comparison of bifunctional ATP sulfurylase/APS kinase and monofunctional ATP sulfurylases shows a limited number of highly conserved arginines and histidines within the sulfurylase domain. Of these conserved residues, His-425, His-428, and Arg-421 are present within or near the HXXH motif whereas His-506, Arg-510, and Arg-522 residues are present in and around the PP-loop. The functional role of these conserved residues was further studied by site-directed mutagenesis. In the HXXH motif, none of the alanine mutants (H425A, H428A, and R421A) had sulfurylase or overall activity, whereas they all exhibited normal kinase activity. A slight improvement in reverse sulfurylase activity (<10% residual activity) and complete restoration of forward sulfurylase was observed with R421K. Mutants designed to probe the PP-loop requirements included H506A, R510A, R522A, R522K, and D523A. Of these, R510A exhibited normal sulfurylase and kinase activity, R522A and R522K showed no sulfurylase activity, and H506A had normal sulfurylase activity but produced an effect on kinase activity (<10% residual activity). The single aspartate, D523A, which is part of the highly conserved GRD sequence of the PP-loop, affected both sulfurylase and kinase activity. This mutational analysis indicates that the HXXH motif plays a role only in the sulfurylase activity, whereas the PP-loop is involved in both sulfurylase and kinase activities. Residues specific for sulfurylase activity have also been distinguished from those involved in kinase activity. (+info)
(6/542) Up-regulation of MDC15 (metargidin) messenger RNA in human osteoarthritic cartilage.
OBJECTIVE: The aim of the study was to investigate the messenger RNA (mRNA) expression of the disintegrin metalloproteinase MDC15 (metargidin, or ADAM-15) in normal and osteoarthritic (OA) articular cartilage. METHODS: In situ hybridization experiments and reverse transcription-polymerase chain reaction (RT-PCR) were performed on tissue samples of adult normal and OA articular cartilage. RESULTS: MDC15 mRNA could be detected in normal articular cartilage by RT-PCR using tissue-extracted total RNA as a template. However, the mRNA level remained below the sensitivity of in situ hybridization. In contrast, in situ hybridizations of OA cartilage revealed an intense staining with the MDC15-specific riboprobes. The extension of the analysis to chondrosarcomas showed a strong up-regulation of MDC15 mRNA in these malignant transformed cells. CONCLUSION: Our results demonstrate a markedly strong up-regulation of MDC15 in adult OA and neoplastic cartilage compared with adult normal articular cartilage, indicating a potential role of the disintegrin metalloproteinase in cartilage remodeling. (+info)
(7/542) Reconstruction and limb salvage after resection for malignant bone tumour of the proximal humerus. A sling procedure using a free vascularised fibular graft.
We assessed the intermediate functional results of eight patients after wide resection of the proximal humerus for malignant bone tumour. We used a free vascularised fibular graft as a functional spacer and a sling procedure to preserve passive scapulohumeral movement. Scapulohumeral arthrodesis was not carried out. Five patients had osteosarcoma, two achondrosarcoma and one a malignant fibrous histiocytoma of the bone. The mean duration of follow-up was 70 months (median, 76) for the seven patients who were still alive at the time of the latest follow-up. One patient died from the disease 12 months after surgery. There were no local recurrences. The functional results were described and graded quantitatively according to the rating system of the Musculoskeletal Tumour Society. Our results were satisfactory with regard to pain, emotional acceptance and manual dexterity. Function and lifting ability were unsatisfactory in two patients. One patient had delayed union between host and graft, but this united after six months without further surgery. Radiographs of the shoulder showed absorption or collapse of the head of the fibula in four of the eight patients and a fracture in another. No functional problems related to absorption or fracture of the head of the fibula were noted. There was no infection or subluxation of the head. We conclude that this is a reasonably effective technique of limb salvage after resection of the proximal humerus. (+info)
(8/542) Fusion of the EWS-related gene TAF2N to TEC in extraskeletal myxoid chondrosarcoma.
Extraskeletal myxoid chondrosarcomas (EMCs) are characterized by a recurrent t(9;22)(q22;q12) translocation, resulting in the fusion of the EWS gene in 22q12 and the TEC gene in 9q22. Here we report that a third member of the EWS, TLS/FUS gene family, TAF2N, can replace EWS as a fusion partner to TEC in EMC. Two tumors, one with a novel t(9;17)(q22;q11) variant translocation and one with an apparently normal karyotype, expressed TAF2N-TEC fusion transcripts. In both cases, the chimeric transcripts were shown to contain exon 6 of TAF2N fused to the entire coding region of TEC. This transcript is structurally and functionally very similar to the EWS-TEC fusions. The exchange of the EWS NH2-terminal part with the TAF2N NH2-terminal part in EMC further underscores the oncogenic potential of these protein domains as partners in fusion genes. (+info)