Dielectric behavior of DNA in water–organic co-solvent mixtures

The radiowave dielectric dispersions of DNA in different water–organic co-solvent mixtures have been measured in the frequency range from 100 kHz to 100 MHz, where the polarization mechanism is generally attributed to the confinement of counterions within some specific lengths, either along tangential or perpendicular to the polyion chain. The dielectric dispersions have been analyzed on the basis of two partially different dielectric models, a continuum counterion fluctuation model proposed by Mandel and a discrete charged site model, proposed by Minakata. The influence of the quality of the solvent on the dielectric parameters has been investigated in water–methanol and water–glycerol mixtures at different composition, by varying the permittivity ?_m and the viscosity η of the solvent phase. The analysis of the dielectric spectra in solvents where electrostatic and hydrodynamic interactions vary with the solvent composition suggests that both the two models are able, in principle, to account for the observed high-frequency dielectric behavior. However, while some certain assumptions are necessary about the polyion structure within the Mandel model, no structural prerequisite is needed within the Minakata model, where the polarization mechanism invoked considers a radial counterion exchange with the outer medium, which is largely independent of the local polyion conformation.     

Relationships between nutrient enrichment,pleurocerid snail density and trematode infection rate in streams

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The Local Complement Activation on Vascular Bed of Patients with Systemic Sclerosis: A Hypothesis-Generating Study

ObjectiveThe role of complement system in the pathogenesis of systemic sclerosis (SSc) has been debated during the last decade but an evident implication in this disease has never been found. We carried out an explorative study on SSc patients to evaluate the expression of soluble and local C5b-9 complement complex and its relation with a complement regulator, the Membrane Cofactor Protein (MCP, CD46) on skin vascular bed as target distinctive of SSc disease. We also analyzed two polymorphic variants in the complement activation gene cluster involving the MCP region.MethodsC5b-9 plasma levels of SSc patients and healthy subjects were analyzed by ELISA assay. Archival skin biopsies of SSc patients and controls were subjected to immunofluorescence analysis to detect C5b-9 and MCP on vascular endothelial cells. The expression of MCP was validated by immunoblot analysis with specific antibody. Polymorphic variants in the MCP gene promoter were tested by a quantitative PCR technique-based allelic discrimination method.ResultsEven though circulating levels of C5b-9 did not differ between SSc and controls, C5b-9 deposition was detected in skin biopsies of SSc patients but not in healthy subjects. MCP was significantly lower in skin vessels of SSc patients than in healthy controls and was associated with the over-expression of two polymorphic variants in the MCP gene promoter, which has been related to more aggressive phenotypes in other immune-mediated diseases.ConclusionsOur results firsty document the local complement activation with an abnormal expression of MCP in skin vessels of SSc patients, suggesting that a subset of SSc patients might be exposed to more severe organ complications and clinical evolution due to abnormal local complement activation.     

Immature embryos culture in Italian red chicory

Chicory (Cichorium intybus L.) embryo maturation in vitro was achieved in B5 medium without growth regulators. Immature embryos were collected at different developmental stages 4–168 h after pollination. Only a few plantlets were obtained from ovules collected shortly after pollination since the embryos at these early stages developed abnormal leaves and roots which regenerated shoots ‘via’ organogenesis. Zygotic embryos collected 24–72 h after pollination needed one month of culture in vitro before acclimation. Embryos collected at the heart or early torpedo stage of development (three days after pollination) produced green plantlets after two weeks of in vitro culture and thus they could be transferred to the greenhouse for acclimation. Culture of zygotic embryos in vitro has shown to be a suitable technique to accelerate the breeding process in biennial cultivated Italian red chicory. In fact it is possible to obtain plantlets ready for performing the selection for the desired agronomic traits one month after pollination. Since flowering occurs after vernalization, the selection can be performed in the correct season before flowering. This revised version was published online in June 2006 with corrections to the Cover Date.     

A Re-Emerging Marker for Prognosis in Hepatocellular Carcinoma: The Add-Value of FISHing c-myc Gene for Early Relapse

Hepatocellular carcinoma is one leading cause of cancer-related death and surgical resection is still one of the major curative therapies. Recently, there has been a major effort to find mechanisms involved in carcinogenesis and early relapse. c-myc gene abnormality is found in hepatocarcinogenesis. Our aim was to analyze the role of c-myc as prognostic factor in terms of overall survival and disease-free survival and to investigate if c-myc may be an important target for therapy. We studied sixty-five hepatocellular carcinomas submitted to surgical resection with curative intent. Size, macro-microvascular invasion, necrosis, number of nodules, grading and serum alfa-fetoprotein level were registered for all cases. We evaluated the c-myc aberrations by using break-apart FISH probes. Probes specific for the centromeric part of chromosome 8 and for the locus specific c-myc gene (8q24) were used to assess disomy, gains of chromosomes (polysomy due to polyploidy) and amplification. c-myc gene amplification was scored as 8q24/CEP8 > 2. Statistical analysis for disease-free survival and overall survival were performed. At molecular level, c-myc was amplified in 19% of hepatocellular carcinoma, whereas showed gains in 55% and set wild in 26% of cases. The 1- and 3-year disease-free survival and overall survival for disomic, polysomic and amplified groups were significantly different (p=0.020 and p=.018 respectively). Multivariate analysis verified that the AFP and c-myc status (amplified vs. not amplified) were significant prognostic factors for overall patients survival. c-myc gene amplification is significantly correlated with disease-free survival and overall survival in patients with hepatocellular carcinoma after surgical resection and this model identifies patients with risk of early relapse (≤12 months). We suggest that c-myc assessment may be introduced in the clinical practice for improving prognostication (high and low risk of relapse) routinely and may have be proposed as biomarker of efficacy to anti-c-myc targeted drugs in clinical trials.     

High serum sCD163/sTWEAK ratio is associated with lower risk of digital ulcers but more severe skin disease in patients with systemic sclerosis

Introduction

Systemic sclerosis (SSc) is an autoimmune disease characterized by chronic inflammation, vascular injury and excessive fibrosis. CD163 is a scavenger receptor which affects inflammatory response and may contribute to connective tissue remodelling. It has recently been demonstrated that CD163 can bind and neutralize the TNF-like weak inducer of apoptosis (TWEAK), a multifunctional cytokine which regulates inflammation, angiogenesis and tissue remodelling. We aimed to investigate the relationships between serum levels of soluble CD163 (sCD163) and soluble TWEAK (sTWEAK) in relation to disease manifestations in SSc patients.

Methods

This study included 89 patients with SSc who had not received immunosuppressive drugs or steroids for at least 6 months and 48 age- and sex-matched healthy controls (HC) from four European centres. Serum concentrations of sTWEAK and sCD163 were measured using commercially available ELISA kits.

Results

The mean serum concentrations of sTWEAK were comparable between SSc patients (mean +/- SD: 270 +/- 171 pg/mL) and HC (294 +/- 147pg/mL, P >0.05). Concentration of sCD163 and sCD163/sTWEAK ratio were significantly greater in SSc patients (984 +/- 420 ng/mL and 4837 +/- 3103, respectively) as compared to HC (823 +/- 331 ng/mL and 3115 +/- 1346 respectively, P <0.05 for both). High sCD163 levels and a high sCD163/sTWEAK ratio (defined as > mean +2SD of HC) were both associated with a lower risk of digital ulcers in SSc patients (OR, 95%CI: 0.09; 0.01, 0.71, and 0.17; 0.06, 0.51, respectively). Accordingly, patients without digital ulcers had a significantly higher sCD163 concentration and sCD163/sTWEAK ratio as compared to SSc patients with digital ulcers (P <0.01 for both) and HC (P <0.05 for both). A high sCD163/sTWEAK ratio, but not high sCD163 levels, was associated with greater skin involvement.

Conclusions

The results of our study indicate that CD163-TWEAK interactions might play a role in the pathogenesis of SSc and that CD163 may protect against the development of digital ulcers in SSc. Further studies are required to reveal whether targeting of the CD163-TWEAK pathway might be a potential strategy for treating vascular disease and/or skin fibrosis in SSc.     

Altered insulin receptor signalling and β-cell cycle dynamics in type 2 diabetes mellitus

Insulin resistance, reduced β-cell mass, and hyperglucagonemia are consistent features in type 2 diabetes mellitus (T2DM). We used pancreas and islets from humans with T2DM to examine the regulation of insulin signaling and cell-cycle control of islet cells. We observed reduced β-cell mass and increased α-cell mass in the Type 2 diabetic pancreas. Confocal microscopy, real-time PCR and western blotting analyses revealed increased expression of PCNA and down-regulation of p27-Kip1 and altered expression of insulin receptors, insulin receptor substrate-2 and phosphorylated BAD. To investigate the mechanisms underlying these findings, we examined a mouse model of insulin resistance in β-cells--which also exhibits reduced β-cell mass, the β-cell-specific insulin receptor knockout (βIRKO). Freshly isolated islets and β-cell lines derived from βIRKO mice exhibited poor cell-cycle progression, nuclear restriction of FoxO1 and reduced expression of cell-cycle proteins favoring growth arrest. Re-expression of insulin receptors in βIRKO β-cells reversed the defects and promoted cell cycle progression and proliferation implying a role for insulin-signaling in β-cell growth. These data provide evidence that human β- and α-cells can enter the cell-cycle, but proliferation of β-cells in T2DM fails due to G1-to-S phase arrest secondary to defective insulin signaling. Activation of insulin signaling, FoxO1 and proteins in β-cell-cycle progression are attractive therapeutic targets to enhance β-cell regeneration in the treatment of T2DM.