Little is yet known about the origin and protective mechanism of free nucleic acids in plasma. We investigated the possibility of these free nucleic acids being particle associated. Plasma samples from colon cancer patients and cell culture media were subjected to various antibody incubations, ultracentrifugation, and RNA extraction protocols for total RNA, epithelial RNA, and mRNA. Flow cytometry using a Ber-EP4 antibody and confocal laser microscopy after staining with propidium iodide were also performed. mRNA levels of the LISCH7 and SDHA genes were determined in cells and in culture media. Ber-EP4 antibody and polystyrene beads coated with oligo dT sequences were employed. We observed that, after incubation, total RNA and mRNA were always detected after membrane digestion, and that epithelial RNA was detected before this procedure. In ultracentrifugation, mRNA was caught in the supernatant only if a former lysis mediated or in the pellet if there was no previous digestion. Flow cytometry determinations showed that antibody-coated microbeads keep acellular structures bearing epithelial antigens apart. Confocal laser microscopy made 1-to 2-mm-diameter particles perceptible in the vicinity of magnetic polystyrene beads. Relevant differences were observed between mRNA of cells and culture media, as there was a considerable difference in LISCH7 mRNA levels between HT29 and IMR90 cell co-cultures and their culture media. Our results support the view that extracellular RNA found in plasma from cancer patients circulates in association with or is protected in a multiparticle complex, and that an active release mechanism by tumor cells may be a possible origin.

No abstract

Dermatomyofibroma represents a rare benign fibroblastic/ myofibroblastic cutaneous tumor that mostly occurs in young adult women. It has been seldom reported in pediatric patients. In this analysis, the clinical, histopathological and immunohistochemical findings of 12 dermatomyofibromas occurring in patients up to 16 years of age are compared with those reported in adults. Six patients were male and six were female. Nine lesions were located on the neck, two on the back and one involved the chest. The usual presentation was as an asymptomatic plaque composed of bland spindled cells arranged in dermal fascicles that were oriented parallel to the epidermis. Immunohistochemically, the lesional cells expressed calponin in 11 cases, smooth muscle actin in six and muscle-specific actin in three. In contrast to prior reports from adults, dermatomyofibromas in pediatric patients do not show a female predilection. In addition, they are mostly located on the neck (56%), while in adults the most frequent location is the shoulder (35%). Dermatomyofibromas seem to stabilize after an initial period of enlargement. Punch biopsy and clinical follow up could be an alternative approach to the surgical excision in some cases of dermatomyofibroma, particularly in instances in which surgery might inflict cosmetic defects.

The secreted mitogen vascular endothelial growth factor, VEGF, plays a pivotal role in angiogenesis. Hypoxia, inactivation of p53 and oncogenic K‐Ras induce VEGF expression. Other factors such as p73 may also affect VEGF levels. Curiously, p73 may also regulate angiogenesis by affecting the expression of the pigment epithelium‐derived factor, PEDF. Additionally, VEGF might harbor additional functions through the activation of E2F transcription factors. Recently, a new VEGF variant formed by alternative splicing, VEGF165b, has been described as exerting anti‐angiogenic activity. We study here whether p73 isoforms levels ‐TAp73 and ΔTAp73‐ and p53 and K‐Ras status affect the expression of the above‐mentioned angiogenesis‐related genes (through the correlation between their expressions), the prognostic value of VEGF165b and PEDF and the correlation between VEGF and E2F‐1 levels. Tumor and normal tissue of 112 colorectal cancer patients was analyzed to evaluate: (i) levels of TAp73, ΔTAp73, VEGF, VEGF165b, PEDF and E2F‐1 by quantitative real‐time RT‐PCR, (ii) p53 status by immunohistochemistry and (iii) mutations in the first exon of K‐Ras by PCR‐SSCP. Tumor characteristics were examined in each patient. Associations were observed between: (i) specific p73 isoforms and VEGF and VEGF165b expression; (ii) ΔEx2p73 variant and downregulation of PEDF; (iii) VEGF and PEDF expression; (iv) inactive p53 and VEGF165b levels; (v) oncogenic K‐Ras and PEDF downregulation; (vi) E2F‐1 and VEGF expressions; (vii) VEGF165b downregulation and poor prognosis parameters of tumors. We conclude that the levels of p73 isoforms could affect the expression of VEGF, VEGF165b and PEDF. This scenario becomes complicated because a feedback between VEGF and PEDF may exist. VEGF may activate the E2F‐1 factor. Mutations in K‐Ras could negatively regulate PEDF expression. p53 inactivation might result in compensatory mechanisms such as over‐expression of VEGF165b. Our data support the role of VEGF165b as a tumor suppressor factor in colorectal carcinogenesis and its possible prognosis value. © 2008 Wiley‐Liss, Inc.

F-NaF PET imaging of the equine distal limb provides useful additional information when compared with CT, MRI and scintigraphy and has the potential for both research and clinical applications in the horse. The Summary is available in Chinese - see Supporting information.