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L Raffaele

Publications and source records attributed to L Raffaele.

At least 19 recordsLinked to original sources
PubMed2006

Cellular and molecular effects of protons: apoptosis induction and potential implications for cancer therapy.

Due to their ballistic precision, apoptosis induction by protons could be a strategy to specifically eliminate neoplastic cells. To characterize the cellular and molecular effects of these hadrons, we performed dose-response and time-course experiments by exposing different cell lines (PC3, Ca301D, MCF7) to increasing doses of protons and examining them with FACS, RT-PCR, and electron spin resonance (ESR). Irradiation with a dose of 10 Gy of a 26,7 Mev proton beam altered cell structures such as membranes, caused DNA double strand breaks, and significantly increased intracellular levels of hydroxyl ions, are active oxygen species (ROS). This modified the transcriptome of irradiated cells, activated the mitochondrial (intrinsic) pathway of apoptosis, and resulted in cycle arrest at the G2/M boundary. The number of necrotic cells within the irradiated cell population did not significantly increase with respect to the controls. The effects of irradiation with 20 Gy were qualitatively as well as quantitatively similar, but exposure to 40 Gy caused massive necrosis. Similar experiments with photons demonstrated that they induce apoptosis in a significantly lower number of cells and in a temporally delayed manner. These data advance our knowledge on the cellular and molecular effects of proton irradiation and could be useful for improving current hadrontherapy protocols.

Apoptosis↗
PubMed2002

Preliminary results on a dedicated silicon diode detector for proton dosimetry.

The present work reports preliminary measurements on the behaviour of a new p-type stereotactic silicon diode. Hi-pSi, produced by Scanditronix and dedicated to proton dosimetry. Diode response was investigated in low-energy proton beams (26.7 MeV and 12 MeV nominal energy), mainly with attention to stability, linearity, dose rate and energy dependence of the detector response. Three different Hi-pSi diodes of the same type were investigated. The diode response was linear with dose and the standard deviation of repeated readings was less than 2.5%. A marked dependence on dose rate was observed for one of the diodes (a response increase of 47% in the 0.7-11 Gy x min(-1) range). After the dose rate and water to silicon mass collision stopping power ratio correction of the diode response in the depth dose measurements, the difference, at the Bragg peak, with respect to the reference chamber was about 4%, ascribed to poor knowledge of the materials in front of the sensitive volume. The diode response was also nearly independent of linear energy transfer (LET) in the 9.6-21.5 MeV effective energy range.

Phantoms, Imaging↗
PubMed2002

An investigation of the operating characteristics of two PTW diamond detectors in photon and electron beams.

The dosimetric properties of two PTW Riga diamond detectors type 60003 were studied in high-energy photon and electron therapy beam. Properties under study were current-voltage characteristic, polarization effect, time stability of response, dose response, dose-rate dependence, temperature stability, and beam quality dependence of the sensitivity factor. Differences were shown between the two detectors for most of the previous properties. Also, the observed behavior was, to some extent, different from what was reported in the PTW technical specifications. The necessity to characterize each diamond detector individually was addressed.

Calibration↗
PubMed2001

A case of multiple congenital anomalies in association with Rett syndrome confirmed by MECP2 mutation screening.

Rett syndrome (RTT) is a severe neurodevelopmental disorder. Apparently normal at birth, girls with RTT undergo developmental regression and acquire a neurological and behavioural phenotype that has been used to define clinical diagnostic criteria for the disorder. Recently mutations in the methyl-CpG binding protein 2 gene (MECP2), located on Xq28 have been identified in females with RTT. We report a girl whose clinical course was complicated by congenital abnormalities of the respiratory tract and gastrointestinal system. In addition neurological abnormalities were evident in the newborn period. By the age of 3 years she had developed a phenotype very suggestive of RTT, but had not demonstrated deceleration of head growth and the development of expressive language was prevented by the presence of the tracheostomy. The clinical impression of RTT was confirmed by the recent finding of a mutation in the MECP2 gene. This case report highlights the importance of considering the clinical diagnosis of RTT even in the presence of other conditions and emphasises that girls with RTT may not be normal from birth.

Abnormalities, Multiple↗
PubMed2001

The late effects of proton irradiation on cell growth, cell cycle arrest and apoptosis in a human melanoma cell line.

The aim of this work is the in vitro study of the late effects of single proton irradiation on HTB63 human melanoma cell growth, cell cycle and cell death. The experimental conditions were focused on analyzing the effects of irradiation on the periphery of tumour that can be, in clinical practice, close to critical organs. Confluent cell monolayers were irradiated with single doses ranging from 1 - 20 Gy, using proton beams having an energy of 22.6 MeV at the target. Antiproliferative effect of protons, cell cycle analysis and initiation of cell death, were followed 48 hours after irradiation. The inhibition of melanoma cell growth was observed, especially after single application of 12 and 16 Gy. Cell cycle analysis and cell viability have shown the G2/M and G1/G0 arrest of irradiated cells correlating with the increase of the applied dose. The flow cytometric analysis has shown presence of apoptotic nuclei. These data demonstrate that irradiation with protons, under the chosen experimental conditions, have significant effects on melanoma cell growth inhibition being dose dependent, G2/M cell cycle arrest and appearance of apoptotic nuclei, even 48 hours after irradiation. The results obtained may help the understanding of the relationship between cell proliferation, death and cell cycle regulation of melanomas after proton irradiation.

Apoptosis↗
PubMed2000

Radiochromic film dosimetry of a low energy proton beam.

In this work some dosimetric characteristics of MD-55-2 GafChromic films were studied in a low energy proton beam (21.5 MeV) directly in a water phantom. The nonlinearity of the optical density was quantified by a factor P(lin). A correction factor P(en), that accounts for optical density dependence on the energy, was empirically determined. The effects of detector thickness in depth dose measurements and of the film orientation with respect to beam direction were investigated. The results show that the MD-55-2 films provide dose measurements with the films positioned perpendicularly to the proton beam. A dosimetric formalizm is proposed to determine the dose to water at depth d, with films oriented perpendicularly to the beam axis. This formalism uses a calibration factor of the radiochromic film determined directly on the proton beam at a reference depth in water, and the P(lin) factor, that takes into account the nonlinearity of the calibration curve and the P(en) factor that, in turn takes into account the change of proton beam energy in water. The MD-55-2 films with their high spatial resolution and the quasiwater equivalent material are attractive, positioned perpendicularly along the beam axis, for the absolute dose determination of very small beam sizes and modulated proton beams.

Calibration↗
PubMed1999

External radiation therapy boost to the vaginal vault: feasibility of intracavitary dosimetry using a commercial diode system.

PURPOSE: An overall check of the whole dosimetry procedure by intracavitary in vivo dosimetry, using n-type silicon diode dosimeter, was performed during 6-MV x-ray irradiation of the vaginal vault. The dose delivered to the isocenter by all treatment fields was evaluated. METHODS AND MATERIALS: The diode dosimeter was calibrated against an ion chamber and tissue maximum ratio, field size factor, SSD factor, and temperature dependence studies were performed. Diode system accuracy, linearity, and reproducibility were also tested. Patients' dose data were collected and comparision was made with respect to treatment-planning dose calculations. Ten patients with cervical cancer and endometrial cancer were treated with surgery and irradiation. During the boost to the vaginal vault, a diode was inserted by an intravaginal device and the vaginal vault was the isocenter of the four fields. The field size generally was not larger than 10 x 10 cm2. RESULTS: Diode-measured "tissue maximum ratio" agreed to within 1% with those measured with an ion chamber in field from 7 x 7 to 10 x 10 cm2. The diode also exhibited a temperature dependence of 0.1% degrees C(-1). For 10 patients treated with a 6-MV beam, the agreement with treatment-planning dose calculations was shown to be better than +/-4%. CONCLUSION: The good accuracy and reproducibility of the diode system shows that determination of the dose at isocenter, for patients treated in the pelvic region, can be performed with n-type diodes accurately. On the other hand, in the vaginal vault boost, external-beam radiotherapy is delivered accurately and in vivo dosimetry is really not indicated.

Calibration↗
PubMed1997

Serologic survey for control of hepatitis C in haemodialysis patients: third-generation assays and analysis of costs.

There is little information about the serologic survey for control of hepatitis C by using third-generation assays among chronic haemodialysis (HD) patients, and no analysis of costs has been made to this end. A serologic survey for control of hepatitis C was performed in 190 HD patients attending a single dialysis unit, using second- and third-generation assays. Costs of both serologic surveys were calculated. Anti-HCV prevalence tested by third-generation assays increased from 25% (48/190) to 28% (53/190) compared to second-generation testing; 56% (9/16) of patients showing uncertain findings by second-generation tests gave unequivocal results by third-generation assays; median duration of HD treatment and raised aminotransferase levels were positively associated (P = 0.004 and P = 0.012, respectively) with anti-HCV detected by third-generation assays. The serologic survey for control of hepatitis C in HD patients at our centre was slightly more expensive by third-generation assays compared to second-generation testing (US$18866 vs US$17200 per year). In summary, the use of third-generation tests largely clarified the uncertain results of second-generation tests; new additional positive patients were detected by third-generation assays compared to second-generation testing. Third-generation assays showed the association of duration of HD treatment and raised aminotransferase levels with anti-HCV antibody, as previously found by first- and second-generation assays. To date, third-generation screening and confirmatory assays seem extremely useful in the serologic survey for control of hepatitis C in HD centres without a considerable outlay.

Adult↗
PubMed1997

Hepatitis G virus infection in chronic dialysis patients and kidney transplant recipients.

BACKGROUND: The cloning of the hepatitis G virus (HGV), a novel RNA virus of the Flaviviridae family, has been very recently developed. HGV is known to be parenterally transmitted and has been detected in several patients with cryptogenic hepatitis. However, little information exists about the epidemiology of HGV infection in renal patients. We studied 178 chronic dialysis patients and 11 renal transplant individuals to evaluate prevalence, risk factors, and clinical manifestations of HGV infection in this population. METHODS: Hepatitis G virus infection has been detected by a modified PCR technology which incorporates digoxigenin-labelled nucleotides into the amplicon. Primers from the non-coding region and the NS-5 region of HGV are utilized for a single round amplification. Using a streptavidin surface and a biotin-labelled capture probe, the labelled nucleic acid is bound through the capture probe to the surface, and the amplified nucleic acid is detected using antibody to digoxigenin. RESULTS: HGV RNA was detected in 6% of chronic haemodialysis (HD) patients (11/172), 36% of renal transplant recipients (4/11), and 17% (1/6) of patients on peritoneal dialysis treatment (CAPD). There were no significant differences between HGV positive and negative patients on chronic HD treatment with regard to several demographic, biochemical and virological features. However, the frequency of anti-HCV antibody was significantly higher in HGV-positive than HGV-negative patients (9/11 (82%) vs 51/161 (32%), P = 0.006). In the whole group of HGV RNA-positive patients, 78% (11/14) had a history of blood transfusion requirements, 14/16 (87%) had co-infection with HCV, and 1 (6%) had co-infection with HBsAg. There was no significant association between HCV genotypes and HGV RNA positivity. Six (37.5%) of 16 HGV RNA-positive patients showed raised aminotransferase values in serum. CONCLUSIONS: Patients on maintenance dialysis and kidney transplant recipients are at increased risk of HGV infection; HGV is very frequently associated to hepatitis C co-infection, regardless of HCV genotype. HGV may be transmitted by blood transfusions but transmission routes other than transfusion are possible; 37.5% of HGV RNA-positive patients showed raised serum aminotransferase levels. Further investigations are necessary to clarify the role of HGV infection in the development of liver disease in this clinical setting.

Aged↗
PubMed1996

IgM antibody response to hepatitis C virus in end-stage renal disease.

BACKGROUND: In HBV infection, as in other viral diseases, antibodies of the IgM class are associated with acute or ongoing infection. In contrast, the significance of this antibody in HCV infection is unclear and data regarding end-stage renal disease (ESRD) patients are lacking. METHODS: We tested sera from 78 ESRD patients (66 chronic dialysis patients, 12 renal allograft recipients) showing anti-HCV IgG antibody, for serum anti-HCV IgM core antibody. A specific solid-phase enzyme-linked immunoassay (HCV IgM EIA, Abbot) was used. In all patients serum HCV RNA was detected by RT-PCR technique, with primers from the 5' untranslated region of the viral genome. RESULTS: Prevalence of anti-HCV IgM core antibody was 22% (17/78). We observed association between prevalence of anti-HCV IgM core antibody and frequency of HCV RNA in the serum. Thus 15 of 45 (33%) sera containing HCV RNA also contained anti-HCV IgM, while two of 33 (6%) HCV RNA negative sera showed anti-HCV IgM core antibody (P = 0.01). There was a significant relationship between absorbance values of anti-HCV IgM core antibody and NS3 (P = 0.01), NS5 (P = 0.04), and core (P = 0.0001) reactivity in RIBA-2 and RIBA-3 assays. Optical density values of anti-HCV IgM were significantly associated with the number of reactive bands in RIBA-2 (P = 0.04) and RIBA-3 (P = 0.03) assays. CONCLUSIONS: 22% of ESRD patients with anti-HCV IgG activity showed anti-HCV IgM core antibody in the serum. Anti-HCV IgM activity seems to correlate positively with HCV viraemia in ESRD population. Testing for this antibody may be useful as a serological marker to indicate the presence of ongoing HCV infection.

Adult↗
PubMed1996

Hepatitis C virus genotypes in chronic dialysis patients.

BACKGROUND: Hepatitis C virus (HCV) infection is highly prevalent in dialysis patients. To further characterize HCV infection in this patient population, we studied the distribution of viral genotypes in 55 patients undergoing chronic dialysis treatment with seropositivity for HCV markers. METHODS: Thirty-two of 55 (58%) patients showed HCV RNA in the serum using reverse transcription polymerase chain reaction (RT-PCR) in the 5'-untranslated region (UTR) of the viral genome. HCV genotyping was performed using biotinylated type-specific oligonucleotide probes after hybridization with amplified sample material. RESULTS: HCV subtype 2a was dominant (56%), followed by HCV subtype 1b (31%), type 3 (3%) and 4 (3%). There was no association between demographic or clinical features of this cohort and HCV genotype. Genotype dependence was observed for antibody response toward the NS4 (c 100-3 and 5-1-1) proteins, which was infrequent in genotype 2a carriers compared with genotype 1b (p = 0.004). CONCLUSIONS: HCV subtype 2a was dominant in our cohort of anti-HCV-positive dialysis patients; there was no association between HCV genotypes and demographic or clinical features of patients; the absence of antibody response toward the NS4-related antigens was frequent in genotype 2a carriers and may serve to predict responses to interferon therapy. The relative homogeneity of the viral population in dialysis patients attending our unit suggests a nosocomial transmission of HCV in this clinical setting.

Adult↗
PubMed1996

Recombinant hepatitis B vaccine use in chronic hemodialysis patients. Long-term evaluation and cost-effectiveness analysis.

The prevalence of hepatitis B virus (HBV) infection in our unit was 45% (86/190); there were 77 (40.5%) and 9 (4.7%) patients with previous and persistent HBV infection, respectively. Recombinant hepatitis B vaccine was given to 118 chronic HD patients with a regimen of 3 double doses administered intramuscularly at 0, 1 and 2 months, obtaining a seroprotection rate of 67% (79/118), 57% (45/79) being high responders. At month 24, 78% (40/51) maintained protective levels of anti-HBs, 45% (18/40) of them being high responders. There was a statistically significant difference between responder and non-responder patients with regard to nutritional parameters such as serum total proteins and mean levels of transferrinemia. The number of diabetic patients was significantly increased in the nonresponder group. Patients with persistent antibodies ('persistent responders') were younger and had a shorter duration of HD treatment compared to those responders who rapidly lost anti-HBs ('transient responders'). Serological positivity for antibodies against hepatitis B core antigen significantly facilitates the decrease of anti-HBs antibodies over time. We detected seven episodes of HBV infection among HD patients at our unit before the beginning of the vaccination program. On the contrary, there were no episodes of HBV infection among responder vaccinees during the 24-month follow-up period. After the initial cost of vaccination, a savings of US$ 3,272 per year was realized by the elimination of frequent serologic screening of vaccine responders.

Adolescent↗
PubMed1996

Virological and histological features of hepatitis C virus (HCV) infection in kidney transplant recipients.

BACKGROUND: Although there are some reports regarding prevalence of anti-HCV antibodies in kidney transplant patients, there are scarce data about viraemia, genotyping and liver histology of HCV infection in kidney transplant recipients. METHODS: We studied the prevalence of anti-HCV antibodies by second-generation screening and confirmatory assays in a cohort of 73 renal allograft recipients. All patients were tested for serum HCV RNA using reverse transcription polymerase chain reaction in the 5'-untranslated region (UTR) of the viral genome. HCV RNA positive patients were subjected to genotype analysis using biotinylated type-specific oligonucleotide probes after hybridization with amplified sample material. Eleven of 73 patients showing raised aminotransferase levels underwent hepatic biopsy. RESULTS: Fifteen of 73 (20%) patients were determined anti-HCV positive. Eleven of 73 (15%) showed detectable serum HCV RNA; no viraemic, seronegative patients were identified. Genotyping showed that HCV subtype 2a was dominant (64%), followed by HCV subtypes 1b (27%) and 1a (9%). Six of 11 (54%) HCV RNA patients and 12 of 62 (19%) HCV RNA negative patients showed raised aminotransferase levels (P = 0.03). Liver biopsies showed histological features of chronic hepatitis with mild or moderate degrees of activity. CONCLUSIONS: The prevalence of anti-HCV antibodies and HCV viraemia was 20% and 15% respectively; there was a good association between anti-HCV anti-bodies and HCV viraemia; hepatic enzyme levels were good indicators of ongoing HCV infection; HCV subtype 2a was prevalent; liver histology showed histological characteristics of chronic hepatitis with mild or moderate degrees of activity.

Adult↗
PubMed1995

Comparison of second-generation screening and confirmatory assays with recombinant antigens and synthetic peptides against antibodies to hepatitis C virus: a study in renal patients.

The aim of this study was to compare some common tests which are nowadays routinely used to screen and to confirm anti-HCV antibodies in renal patients. There was agreement between Ortho 2 and Abbott 2 in 94% of samples; structural and nonstructural beads of the Abbott supplementary assay were in agreement with 4-RIBA in 98 and in 85% of samples, respectively; 61% of Ortho 2 samples and 65% of Abbott 2 samples were confirmed by 4-RIBA; there was a correlation between semiquantitative analysis of screening tests (Ortho 2 and Abbott 2) and positive results by 4-RIBA; 36 and 33% of Ortho-2- and Abbott-2-positive samples were 4-RIBA indeterminate: in these instances more sophisticated techniques (polymerase chain reaction) (PCR) could be useful as a third-level assay. The comparison between Ortho 2, based on recombinant antigens, and Innotest, based on synthetic peptides, showed agreement only in 44% of samples, but this preliminary comparison cannot afford definitive conclusions. These findings suggest that second-generation assays may sometimes yield conflicting results in renal patients. These contradictions will be resolved by new HCV tests or PCR.

Antigens, Viral↗
PubMed1995

Wedge factor changes with depth and field size on a linear accelerator with a motorized wedge.

The wedge factor was experimentally determined as a function of field size and phantom depth for 6-MV X-rays; measurements were performed on a linear accelerator with a motorized wedge filter (universal wedge, nominal wedge angle = 60 degrees). As a result of our experimental work, we can state that: 1) The wedge factor increases linearly with phantom depth (0.275%/cm), almost independent of field size; this change was experimentally related to the beam "hardening" caused by the high Z value of wedge material, as shown by the increase in wedged-field PDD with respect to the corresponding open-field PDD. Neglecting this variation can induce systematic errors in delivered dose, especially when deep-seated tumors are treated with wedge fields. 2) The wedge factor changes, for rectangular fields, according to the "equivalent square law", and not to the dimension in the wedged direction.

Filtration↗
PubMed1995

Virological characteristics of hepatitis C virus infection in chronic hemodialysis patients: a cross-sectional study.

Detection of hepatitis C virus viremia (HCV RNA) in serum of hemodialysis (HD) patients is crucial for documenting ongoing infection because the clinical and epidemiological importance of anti-HCV positivity is not clear. HCV viremia was studied in 104 HD patients by reverse transcription polymerase chain reaction (RT PCR) using primers localized in the 5' non-coding region of the viral genome. We used two different methods to detect HCV RNA: a direct PCR amplification of HCV RNA from human serum, and a standard RT PCR procedure (requiring the RNA extraction step). There were 50 (48%) anti-HCV positive patients in this population. Twenty-two (21.1%) out of 104 patients showed HCV RNA in serum by standard RT PCR technique: they belonged to the anti-HCV positive patient group, whereas all anti-HCV negative patients were HCV RNA negative. Prevalence of HCV RNA was more than doubled when standard RT PCR was used compared to direct RT PCR protocol. There was a good association between serum HCV RNA and circulating anti-HCV antibodies, tested by second-generation ELISA and RIBA assays. HCV viremia was not associated with either the presence or the absence of a particular RIBA antibody specificity. AST and ALT levels had no predictive value for HCV viremia, because they were repeatedly normal in the majority of viremic patients (16/22: 73%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cross-Sectional Studies↗