Both homo and heterodimers of Marek's disease virus encoded Meq protein contribute to transformation of lymphocytes in chickens

Marek' disease virus serotype-1, also know as Gallid herpesvirus 2 (GaHV-2), elicits T-cell lymphomas in chickens. The GaHV-2 genome encodes an oncoprotein, Meq, with similarity to the Jun/Fos family of proteins. We have previously shown that Meq homodimers are not sufficient to induce lymphomas in chickens. In this study, we investigated the role of Meq heterodimers in the pathogenicity of GaHV-2 by generating a chimeric meq gene, which contains the leucine zipper region of Fos (meqFos). A recombinant virus containing the meqFos gene in place of parental meq, rMd5-MeqFos, was not capable of transforming chicken lymphocytes, indicating that heterodimerization of Meq alone is not sufficient for transformation. In addition, the recovery of the oncogenic phenotype by a recombinant virus encoding one copy each of MeqGCN (homodimer) and MeqFos (heterodimer) conclusively demonstrates that both homo and heterodimerization of Meq are required for oncogenesis.     

Predicting survival in patients with hepatocellular carcinoma: a UK perspective.

BACKGROUND AND AIMS: Hepatocellular carcinoma (HCC) is a cancer of rising incidence in the UK. The aim of this study was to compare the Okuda, Cancer of the Liver Italian Program (CLIP), and Barcelona Clinic Liver Cancer (BCLC) classifications as predictors of survival in UK patients with HCC. METHODS: Data were analysed from a prospective database maintained in a specialist hepatobiliary unit from 1998 to 2003. Each system was assessed for its discriminatory power, monotonicity of gradient, and independent contribution to prediction of mortality status based on a multivariate model. RESULTS: One hundred and two patients (77 males, 25 females) were identified with a median age of 65 (range, 14-87) years. The overall median survival time was 13 months and the one- and five-year survival rates were 52.9% (95% CI: 43.2%, 62.6%) and 35.3% (95% CI: 26.0%, 44.6%), respectively. All three classification systems had the capacity to differentiate between patient survival times across different stages. The Okuda system was superior in overall discriminatory power and in strength of monotonicity. The BCLC system, however, made the highest independent contribution of all three systems in predicting survival in the Cox regression model. CONCLUSIONS: All three classification systems were effective in predicting survival for patients with HCC in a UK population.     

High-resolution array CGH clarifies events occurring on 8p in carcinogenesis

Background  

Rearrangement of the short arm of chromosome 8 (8p) is very common in epithelial cancers such as breast cancer. Usually there is an unbalanced translocation breakpoint in 8p12 (29.7 Mb – 38.5 Mb) with loss of distal 8p, sometimes with proximal amplification of 8p11-12. Rearrangements in 8p11-12 have been investigated using high-resolution array CGH, but the first 30 Mb of 8p are less well characterised, although this region contains several proposed tumour suppressor genes.     

A monitor unit verification calculation in intensity modulated radiotherapy as a dosimetry quality assurance

In standard teletherapy, a treatment plan is generated with the aid of a treatment planning system, but it is common to perform an independent monitor unit verification calculation (MUVC). In exact analogy, we propose and demonstrate that a simple and accurate MUVC in intensity modulated radiotherapy (IMRT) is possible. We introduce the concept of modified Clarkson integration (MCI). In MCI, we exploit the rotational symmetry of scattering to simplify the dose calculation. For dose calculation along a central axis (CAX), we first replace the incident IMRT fluence by an azimuthally averaged fluence. Second, the Clarkson integration is carried over annular sectors instead of over pie sectors. We wrote a computer code, implementing the MCI technique, in order to perform a MUVC for IMRT purposes. We applied the code to IMRT plans generated by CORVUS. The input to the code consists of CORVUS plan data (e.g., DMLC files, jaw settings, MU for each IMRT field, depth to isocenter for each IMRT field), and the output is dose contribution by individual IMRTs field to the isocenter. The code uses measured beam data for Sc, Sp, TPR, (D/MU)ref and includes effects from multileaf collimator transmission, and radiation field offset. On a 266 MHz desktop computer, the code takes less than 15 to calculate a dose. The doses calculated with the MCI algorithm agreed within +/-3% with the doses calculated by CORVUS, which uses a 1 cm x 1 cm pencil beam in dose calculation. In the present version of MCI, skin contour variations and inhomogeneities were neglected.     

Suppression of in vivo tumor growth and induction of suspension cell death by tissue inhibitor of metalloproteinases (TIMP)-3

Tissue inhibitor of metalloproteinases-3(TEMP-3), a novel memberof TEMP family genes, has been recently cloned and shown tobe expressed in preneoplastic but not in neoplastic mouse JB6epidermal cells (Sun et al. 1994 Cancer Res., 54, 11139). Thisdown regulation of the gene appears to be attributable at leastin part to alteration of gene methylation (Sun et al. 1995 J.Biol Chem., 270, 19312). Little is known, however, about therole of TEMP-3 in human cancers. We screened several human tumorcell lines for TEMP-3 expression and found that a colon carcinomaline, DLD-1, did not express TEMP-3. If down regulation of TIMP-3is causally related to carcino-genesis, re-expression by transfectionmay reverse the tumor cell phenotype. We therefore overexpressedhuman TEMP-3 in DLD-1 cells. TEMP-3 transfectants showed a serum-dependentgrowth inhibition in monolayer culture and a decreased growthpotential in nude mice in a manner dependent on the level ofTEMP-3 expression. A transfectant expressing a high level ofactive hTEMP-3 completely lost the ability to form tumors followings.c. injection into nude mice. We also tested TEMP-3 expressingcells and neocontrol TEMP-3 negative cells for their abilityto grow in liquid suspension culture, since both cells grewin semi-solid soft agar. As compared to neocontrol cells, TIMP-3over-expressors formed large aggregates, followed by cell death.This effect was not mimicked by BB94, a broad MMP inhibitor.We conclude from this study that (i) TEMP-3 overexpression inhuman colon carcinoma cells induces growth arrest in low serumconditions and inhibits in vivo tumor growth and (ii) the TEMP-3-inducedlarge aggregate formation and subsequent cell death under suspensiongrowth cannot be explained by its MMP inhibitory activity.     

New PET imaging agent for the serotonin transporter: [(18)F]ACF (2-[(2-amino-4-chloro-5-fluorophenyl)thio]-N,N-dimethyl-benzenmethanamine)

A new F-18-labeled phenylthiophenyl derivative specific for imaging of serotonin transporters (SERT) in the brain by positron emission tomography (PET) is described. Fluorinated phenylthiophenyl derivative, ACF, 2-[(2-amino-4-chloro-5-fluorophenyl)thio]-N,N-dimethyl-benzenmethanamine, was prepared by first coupling 2,5-dichloro-4-nitroaniline with 2-mercapto-N,N-dimethylbenzamide. The amino group of the coupled adduct was converted to a fluoro group through a Schiemann reaction. Subsequently, a one pot reduction of both nitro and amide groups by BH(3)-tetrahydrofuran yielded the nonradioactive ACF (yield 25%). In vitro binding assays using cell membrane homogenates of LLC cells expressing SERT, dopamine transporters (DAT), or norepinephrine transporters (NET) showed excellent binding affinity and selectivity for SERT (K(i) = 0.05, 3020, and 650 nM for SERT, DAT, and NET, respectively). For preparation of the [(18)F]ACF, the NH(2) group of the initially coupled adduct was converted to the trimethylammonium salt, which was replaced by [(18)F]fluoride in the presence of Kryptofix 222 and potassium carbonate. The final product, [(18)F]ACF, was obtained after a borane and stannous chloride reduction reaction. The combined two step reaction gave a radiochemical yield of 10-15% (EOB) and a radiochemical purity of >99%. Synthesis of the novel PET tracer, [(18)F]ACF, as a probe for binding to SERT in the brain was successfully achieved. The new tracer [(18)F]ACF showed excellent brain penetration and selective localization after an iv injection in rats (brain uptake at 2, 30, 60, 120, and 240 min was 3.27, 1.28, 0.69, 0.21, and 0.06% dose/organ, respectively). The hypothalamus/cerebellum ratio at 60 min post iv injection was 3.55. This specific localization in the hypothalamus was blocked by pretreatment of (+)McN5652. This novel ligand is a potential PET tracer for in vivo evaluation of SERT in the brain.     

Improved microvessel repair: laser welding with an anti-thrombotic solder

BACKGROUND AND OBJECTIVES: Concentrated protein solutions can be used as thermally polymerized solders in laser welding. Solders supplemented with biologically active chemicals may provide in situ drug delivery for localized therapeutics. These studies characterize a serum albumin (SA) solder containing heparin, designed to reduce microvascular thrombosis rates. STUDY DESIGN/MATERIALS AND METHODS: Samples of heparin added to 30% SA to obtain heparin-to-albumin molar ratios (HAMR) of 4:1 and 2:1 were thermally polymerized, and heparin release into saline was measured. Using a rat thrombosis model, patency was determined for suture, and 0 U/ml (control), 2.5 U/ml, 50 U/ml heparin solder repairs. RESULTS: Heparin release was five times higher for 4:1 than 2:1 HAMR solder acutely, but was equivalent after 2 days. Animal patency rates were: 50% suture, 0% control, 50% low heparin, 66% high heparin (P < 0.05 vs. control). CONCLUSIONS: Solders incorporating heparin should provide in situ anti-thrombotic therapy reducing the risk of microvascular thromboses.     

Radioiodinated styrylbenzene derivatives as potential SPECT imaging agents for amyloid plaque detection in Alzheimer's disease

Development of probes for β-amyloid (Aβ) plaques, a critical factor associated with Alzheimer’s disease (AD), provides important tools for studying their role in AD. Previously, we reported [¹²⁵I]IMSB and [¹²⁵I]ISB as excellent probes for Aβ plaque labeling. Despite their exquisite in vitro binding characteristics, low brain uptakes (likely due to two ionizable carboxylic acid groups) limited their potential as in vivo imaging agents. To improve brain penetration, we have successfully prepared a neutral radioiodinated probe [¹²⁵I]3. The improved probe displayed good binding affinity for Aβ aggregates (K_i=2.0 ± 0.2 using Aβ40 aggregates). In addition, the brominated counterpart displayed fluorescent-staining properties of Aβ plaques in postmortem AD brain sections similar to BSB, a fluoroscent probe reported previously. [¹²⁵I]3 gave excellent plaque labeling by film autoradiography of AD brain sections. Unlike [¹²⁵I]IMSB (which preferentially detects Aβ40 plaques), the improved radioioinated probe, [¹²⁵I]3, can readily detect plaques containing aggregates of both Aβ40 and Aβ42. The initial brain uptake of [¹²⁵I]3 in normal mice at 2 min p.i. was moderate (0.18% ID) and displayed a very slow washout from the brain (0.11 %.ID at 4 h p.i). Taken together, these data suggest that [¹²⁵I]3 is useful for in vitro plaque detection, it may not be suitable for in vivo monitoring of Aβ progression and deposition.