The E LiBANS project: Thermal and epithermal neutron sources based on a medical Linac.

The E_LIBANS project (INFN) aims at producing neutron facilities for interdisciplinary irradiation purposes among which pre-clinical research for BNCT. After the successful setting-up of the thermal neutron source based on a medical LINAC, a similar apparatus for epithermal neutrons has been developed. Both structures are based on an Elekta 18 MV coupled with a photoconverter-moderator system which deploys the (γ,n) reaction to convert the X-rays into neutrons. This communication describes the two neutron sources and the results obtained in their characterization.

DEVELOPING RADIATION RESISTANT THERMAL NEUTRON DETECTORS FOR THE E_LIBANS PROJECT: PRELIMINARY RESULTS.

Radiation-resistant, gamma-insensitive, active thermal neutron detectors were developed to monitor the thermal neutron cavity of the E_LIBANS project. Silicon and silicon carbide semiconductors, plus vented air ion chambers, were chosen for this purpose. This communication describes the performance of these detectors, owing on the results of dedicated measurement campaigns.

INTENSE THERMAL NEUTRON FIELDS FROM A MEDICAL-TYPE LINAC: THE E_LIBANS PROJECT.

The e_LiBANS project aims at producing intense thermal neutron fields for diverse interdisciplinary irradiation purposes. It makes use of a reconditioned medical electron LINAC, recently installed at the Physics Department and INFN in Torino, coupled to a dedicated photo-converter, developed within this collaboration, that uses (γ,n) reaction within high Z targets. Produced neutrons are then moderated to thermal energies and concentrated in an irradiation volume. To measure and to characterize in real time the intense field inside the cavity new thermal neutron detectors were designed with high radiation resistance, low noise and very high neutron-to-photon discrimination capability. This article offers an overview of the e_LiBANS project and describes the results of the benchmark experiment.

Design and simulation of an optimized e-linac based neutron source for BNCT research.

The paper is focused on the study of a novel photo-neutron source for BNCT preclinical research based on medical electron Linacs. Previous studies by the authors already demonstrated the possibility to obtain a mixed thermal and epithermal neutron flux of the order of 10(7) cm(-2) s(-1). This paper investigates possible Linac's modifications and a new photo-converter design to rise the neutron flux above 5 10(7) cm(-2) s(-1), also reducing the gamma contamination.

Karyotype variations in Italian populations of the peach-potato aphid Myzus persicae (Hemiptera: Aphididae).

In this study, we present cytogenetic data regarding 66 Myzus persicae strains collected in different regions of Italy. Together with the most common 2n = 12 karyotype, the results showed different chromosomal rearrangements: 2n = 12 with A1-3 reciprocal translocation, 2n = 13 with A1-3 reciprocal translocation and A3 fission, 2n = 13 with A3 fission, 2n = 13 with A4 fission, 2n = 14 with X and A3 fissions. A 2n = 12-13 chromosomal mosaicism has also been observed. Chromosomal aberrations (and in particular all strains showing A1-3 reciprocal translocation) are especially frequent in strains collected on tobacco plants, and we suggest that a clastogenic effect of nicotine, further benefited by the holocentric nature of aphid chromosomes, could be at the basis of the observed phenomenon.

Interferon-alpha suppresses liver cell proliferation in patients with chronic hepatitis C virus infection.

SUMMARY: Interferon (IFN) therapy has been shown to reduce the risk of hepatocellular carcinoma (HCC) in patients with chronic hepatitis C, including virological nonresponders (NR). Whether IFN suppresses liver cell proliferation, i.e. the relevant risk factor for HCC, is unknown. The aim of the study was to evaluate the effect of IFN therapy on liver cell proliferation in chronic hepatitis C. The proliferating cell nuclear antigen-labelling index (PCNA-LI) was assessed prior to and at the end of therapy in the liver of 29 patients with chronic hepatitis C who received 3 MU IFN-alpha2b thrice weekly for 24-48 weeks. Overall, the median value of PCNA-LI was significantly reduced from 2.6% to 1.1% at the end of therapy (P < 0.0001). At baseline, PCNA-LI median values were similar in the 15 virological responders compared with the 14 NRs (2.3%vs 3.4%, P = 0.121) and at the end of therapy, median changes of PCNA-LI (-1.4%vs-1.1%, P = 0.089) were also similar although there was a higher decline of the proliferation index in responders with respect to NRs at the end of therapy (0.7%vs 1.6%, P = 0.004). In the two groups, the rate of fibrosis score reduction was also similar (7%vs 20%, P = 0.326). In contrast, the histological activity index was more often reduced in responders than in NRs both at the >or=2 and >or=4 points reduction level (80%vs 36%, P = 0.02 and 53%vs 14%, P = 0.03, respectively). The study showed a significant suppression of liver cell proliferation in IFN-treated patients with chronic hepatitis C. Although the strongest IFN effect was observed in virological responders, a reduction of proliferative activity was also seen in virological NRs.

Proliferating cell nuclear antigen assessed by a computer-assisted image analysis system in patients with chronic viral hepatitis and cirrhosis.

BACKGROUND: Assessment of liver cell proliferation by immunodetection of proliferating cell nuclear antigen may predict regenerative potential and survival of liver and hepatocellular carcinoma risk in patients with chronic viral hepatitis. AIM: To evaluate proliferating cell nuclear antigen status and its clinical significance in a large cohort of patients with chronic viral hepatitis and different degree of liver damage by a computer assisted imaging analysis system. MATERIALS: Liver biopsies from 358 patients with chronic hepatitis (259 males, 49 years, 63% with hepatitis C infection, 27% with hepatitis B virus, 10% with multiple infections) were studied. METHODS: Proliferating cell nuclear antigen was localised by immunoperoxidase on microwave oven pre-treated formalin-fixed, paraffin embedded sections using PC10 monoclonal antibody. Proliferating cell nuclear antigen labelling index was calculated by an automated imaging system (Immagini e Computers, Milan, Italy). RESULTS: Mean proliferating cell nuclear antigen labelling index ranged from 0.1% for patients with minimal changes to 3.6% for those with cirrhosis and hepatocellular carcinoma. Overall, proliferating cell nuclear antigen labelling index was higher in males, in older patients, in multiple infections and in hepatitis C virus compared to hepatitis B virus related cases. By linear regression analysis, proliferating cell nuclear antigen labelling index correlated with older age, male gender; higher transaminase levels, hepatitis C virus, higher histological gradIng and staging: by multivariate analysis male gender, hepatitis C virus, higher grading and staging resulted as independent variables. Both hepatitis C virus or hepatitis B virus cirrhotics had similar liver cell proliferation rate but those with hepatitis B virus had higher prevalence of liver cell dysplasia with respect to those with hepatitis C virus. CONCLUSIONS: Proliferating cell nuclear antigen labelling index was a reliable assay for assessing liver cell proliferation rate in patients with chronic viral hepatitis and correlated with liver disease severity