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Biomedical subjects

C De Angelis

Publications and source records attributed to C De Angelis.

At least 37 records · Page 2Linked to original sources
PubMed2002

The importance of endoscopic ultrasonography in the management of low-grade gastric mucosa-associated lymphoid tissue lymphoma.

BACKGROUND: Anti-Helicobacter pylori therapy has been reported to cause regression of low-grade gastric mucosa-associated lymphoid tissue lymphoma in a high percentage of patients. However, in some patients, these lesions persist despite antibiotic treatment. AIM: To determine the various endosonographic findings that may predict the regression of low-grade gastric mucosa-associated lymphoid tissue lymphoma post-antibiotics. METHODS: Seventy-six patients with Helicobacter pylori-positive gastric mucosa-associated lymphoid tissue lymphoma were studied. Follow-up data were available on 51 patients. All patients were treated with antibiotics. Participants underwent pre- and post-anti-Helicobacter pylori therapy endoscopy with gastric biopsies, followed by endoscopic ultrasonography examination of the stomach. RESULTS: Helicobacter pylori was eradicated in 45 of 51 (88%) patients. At the 2-year follow-up, complete regression of mucosa-associated lymphoid tissue lymphoma was seen in 28 of 51 (55%) patients: 12 of 16 (75%) patients in stage T1m N0, 11 of 19 (58%) patients in stage T1sm N0, four of eight (50%) patients in stages T1m N1 and T1sm N1, and one of four (25%) patients in stage T2 N0. None of the stage T2 N1 patients achieved clinical regression. CONCLUSIONS: Endoscopic ultrasonography evaluation of gastric mucosa-associated lymphoid tissue lymphoma plays a pivotal role in the initial staging and post-treatment follow-up evaluation of these lesions. Accurate staging is essential in the determination of the optimal treatment modality.

Adult↗
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

Alanine response to proton beams in the 1.6-6.1 MeV energy range.

Alanine response to low-energy protons was studied with alanine dosemeters of 2 mm thickness, irradiated with proton beams of energy in the 1.6-6.1 MeV range. The detector's range-averaged relative effectiveness to 60Co radiation ranged from 0.61 to 0.65. For fluence values up to 5 x 10(10) protons x cm(-2), the alanine response was linear.

Alanine↗
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↗
PubMed2002

A correction method for diamond detector signal dependence with proton energy.

Small dosimeters as solid state detectors can be useful for the dosimetric characterization and periodic quality control of radiotherapy proton beams. The calibration of solid state detectors for proton beams is not a solved problem especially for ophthalmologic proton beams, where these detectors present a LET-dependent signal. In this work a PTW diamond detector has been selected because of its good signal reproducibility (0.3%) and stable response with accumulated dose. A method that takes into account the LET dependence of the diamond detector signal, at 62 MeV proton beam, is here proposed. In particular an empirical correction factor, kDD(Eo) (Rres), has been determined as a function of the residual range quality index, to correct the diamond detector signal for a proton beam of incident effective energy E0= 62 MeV. A dedicated software allows us to use the diamond detector as an on-line reference dosimeter, where an ionization chamber may be difficult to use, or for periodic quality control procedures. The article also reports a comparison between the signal dependence on proton energy of silicon, diamond, and radiochromic film detectors.

Biophysical Phenomena↗
PubMed2002

[Ultrasonographic and biochemical screening of adnexal masses before operative laparoscopy].

BACKGROUND: The object of our study was to evaluate how reliable ultrasonographic and biochemical screening of adnexal masses are in the selection of patients eligible for operative laparoscopy. METHODS: The study was performed at the First Clinic of Obstetrics and Gynecology, University of Rome La Sapienza, Italy. Eighty-seven women of 36.8 +/- 12 years of age, who underwent operative laparoscopy between January 1999 and January 2000 to remove an adnexal lesion, were enrolled. These adnexal lesions had been previously diagnosed on the basis of a pelvic ultrasonographic imaging; this was performed because of follow-up procedure or pelvic pain. The lesions were evaluated preoperatively according to Sassone echographic scoring system. The CA-125 level was determined in 58 patients. RESULTS: Surgery was successful in all 87 cases. In one case the operative laparoscopy had to be turned into laparotomy since the histologic examination revealed an atypical proliferative mucinous cystoadenoma. Sassone total average echographic score was 6.0 +/- 1.7; this is below the discriminant cut-off for malignancy (9). The only case in which Sassone score reached 10 was an atypical cystoadenoma. The CA-125 level was higher than 35 IU/ml (cut-off of this marker) in 13.7% of the patients; these were all affected by endometriosis or had a hemorrhagic corpus luteum. In the patient with atypical cystoadenoma, the CA-125 level was within normal range (29.1 UI/ml). The post-operative period was uneventful in all cases but one, in which the occurrence of pulmonary thromboembolism required a prolonged hospitalization. CONCLUSIONS: The use of Sassone echographic scoring system proved to be very useful and effective in the selection of the patients. Tumor markers are relevant factors only if their evaluation is accompanied by an accurate anamnesis and is supported by the findings of abdominal and transvaginal ultrasonography.

Adnexal Diseases↗
PubMed2001

Modified autonomic balance in offsprings of diabetics detected by spectral analysis of heart rate variability.

This study was performed to evaluate the influence of family history for non-insulin-dependent diabetes mellitus (NIDDM) on autonomic balance. The latter was assessed by spectral analysis of heart rate variability (SA-HRV) and by analyzing the relative contribution of low-frequency (LF) and high-frequency (HF) components. Twenty glucose normotolerant offsprings of NIDDM parents and 20 controls underwent a 1-hour continuous electrocardiogram (ECG). LF and HF (mean +/- SEM in normalized units [NU]), respectively increased and decreased in offspring versus controls. The LF/HF ratio (mean +/- SEM) significantly increased (LF/HF = 3.25 +/- 0.7 v 1.45 +/- 0.5, P <.0001 offsprings v controls). To test a stimulated response, a passive tilting (+ 90 degrees ) after 30 minutes of bed rest (0 degrees ) was performed in a subsample of subjects (10 offsprings v 10 controls). During bed rest, we found significantly higher values of the LF/HF ratio in offsprings versus controls (1.93 +/- 0.3 v 1.08 +/- 0.2, P <.05), whereas in the head-up position, the LF/HF ratio value increased to the same levels in the 2 groups (6.48 +/- 1.3 v 6.89 +/- 1.4, not significant [NS]). NIDDM family history is characterized in the basal condition by an imbalance of the autonomic system, which, compared with controls, is expressed by a higher weight of sympathetic and a lower weight of parasympathetic components. No significant differences can be found under stimulated conditions.

Adult↗
PubMed2001

The effect of the eradication of Helicobacter pylori infection on hemorrhage because of duodenal ulcer.

The cost of a recurrently bleeding duodenal ulcer (DU) is very high, both from a human and an economic point-of-view. Helicobacter pylori infection plays an important role in the pathogenesis of DU disease and its complications, such as bleeding. Cure of H. pylori infection is recommended in patients with DU and its complications, although in the latter case, the most efficient management is not yet a defined issue. In particular, acid secretion inhibitors may not contribute to long-term cure. Our aims were to ascertain whether the recurrence of bleeding because of DU could be prevented by H. pylori eradication and whether long-term inhibition of gastric acid output is needed to prevent recurrence. Eighty-four patients (65 men; mean age, 55.1 years), who had bled because of recurrent DU, were followed after the cure of H. pylori infection. None of the patients were on therapy with nonsteroidal antiinflammatory drugs. Successful cure of H. pylori was determined by gastroscopy, histology, and serology performed at 3, 6, 12, 24, and 48 months after the eradication treatment. A 13C urea breath test was performed when the results of serology were unclear and also at recurrence of DU or bleeding. After the antibiotic treatment, 46 patients stopped all medications, whereas 38 continued long-term therapy with histamine type 2 receptor antagonists. During a mean follow-up period of 47.2 months (range, 37-65 months), recurrence of DU at endoscopy was observed in three patients in each group (p = 0.56), but none bled again. We conclude that H. pylori eradication prevents DU recurrence and rebleeding, that reinfection rate by H. pylori after cure was nil at 4 years, and that long-term inhibition of acid secretion may not improve outcome after cure of H. pylori, even in patients whose DU was complicated by hemorrhage.

Duodenal Ulcer↗
PubMed2000

Determination of phenolic antioxidants in aviation jet fuel.

The world-wide aviation jet fuel used for civil and military aircraft is of a kerosene type. To avoid peroxide production after the refinery process a specific antioxidant additive should be added on fuel. The antioxidants generally used are based on hindered phenols in a range of concentration 10-20 microg/ml. In the present work a specific method to measure the concentration of phenolic antioxidants is shown. The method is based on a liquid chromatographic technique with electrochemical detection. The technique, because of its selectivity, does not require sample pre-treatments. The analysis of a 5-10 ml fuel sample can be performed in less than 10 min with a sensitivity of 0.1 microg/ml and a RSD=2.5%. A comparison with another highly selective gas chromatographic technique with mass spectrometric detection with selected ion monitoring (GC-MS-SIM) is reported. The sensitivity of GC-MS-SIM method was 2 microg/ml with a RSD=3.1%.

Antioxidants↗
PubMed2000

Electron arc therapy treatment planning verification with alanine/EPR dosimetry.

Alanine/EPR dosimetry was applied to measure dose distributions during electron arc therapy treatments generated by electron beams moving isocentrically over a stated arc. Alanine-polyethylene pellets, prepared at ISS according to the NIST recipe, inserted in a homogeneous cylindrical and anthropomorphic phantoms, were used. Preliminary, alanine response to static electron beams in the (6-20) MeV nominal energy range was studied. Then alanine dosimetry was applied to determine the dose versus the gantry angle at a reference point in a cylindrical homogeneous phantom. Finally, arc therapy treatment planning verification was performed in anthropomorphic phantom.

Alanine↗
PubMed2000

Hyperinsulinaemia in offspring of Type 2 diabetic patients: impaired response of carbohydrate metabolism, but preserved cardiovascular response.

AIMS: To investigate the effects of endogenous insulin on haemodynamics in nine offspring of Type 2 diabetic patients (P), compared with 18 subjects without family history of diabetes (C), all with normal glucose tolerance. METHODS: All subjects underwent a 180-min oral glucose tolerance test with continuous blood pressure and ECG recording. Low-to-high frequency ratio (LF/HF), an index of the sympatho-vagal balance, was calculated by heart rate spectral analysis. RESULTS: At baseline, LF/HF correlated with fasting plasma insulin (r = 0.44, P < 0.03) and with insulin/glucose ratio (r = 0.46, P < 0.03). Plasma insulin, basally similar in the two groups, was significantly increased in P (342 +/- 34.2) when compared to C (177.6 +/- 25.2 pmol/l), P < 0.005 from time 30min onward. Blood glucose, also similar at baseline, remained not significantly different in P (5.74 +/- 0.25) vs. C (5.08 +/- 0.27 mmol/l), throughout the study. Diastolic blood pressure significantly decreased in P, but not in C during the first hour of the study. Finally, LF/HF ratio significantly increased in P (2.5 +/- 0.4 vs. C, 1.7 +/- 0.2) during the first hour. CONCLUSIONS: In conclusion, the offspring of Type 2 diabetic patients with normal glucose tolerance display an increased insulin secretion; however, they are not resistant to the haemodynamic effects of insulin, as suggested by the reduction of diastolic blood pressure. This, in turn, may determine a chronic sympathetic activation, which could be involved in the pathogenesis of Type 2 diabetes mellitus.

Adult↗
PubMed2000

Covered metal stents for management of inoperable malignant colorectal strictures.

BACKGROUND: Metal stents have been reported as an effective alternative to surgery for the palliation of patients with colorectal neoplastic obstruction. Because most of the published series describe the use of uncovered stents, the purpose of our study was to prospectively evaluate the effectiveness, feasibility, safety, and outcome of covered stents for the palliative treatment of malignant colorectal strictures. METHODS: Sixteen patients with advanced distal colorectal cancer underwent placement of 10 and 12 cm long, 23 mm diameter covered stents under fluoroscopic and endoscopic control. Clinical and endoscopic follow-up was scheduled at 3- to 6-week intervals. RESULTS: Stent insertion was successful in 15 of 16 patients (93%). Perforation occurred in one patient during stent placement requiring colostomy. Relief of bowel obstruction was documented in all successfully treated patients. The median follow-up was 21 weeks (range 1 to 46). No recurrence of obstruction was observed during the follow-up period. Stent migration occurred in 2 patients, 7 and 21 days after stent placement. CONCLUSIONS: Covered stents may provide safe and effective palliation of patients with malignant rectosigmoid strictures. Prolonged luminal patency and sealing of fistulous tracts are potential advantages of covered versus uncovered stents in the palliative treatment of colorectal malignancies. ¿

Aged↗
PubMed2000

Dosimetric characterization of silicon and diamond detectors in low-energy proton beams.

The dosimetric behaviour of a Scanditronix p-type silicon diode and a PTW natural diamond detector was studied in low-energy proton beams in the 8.3-21.5 MeV range. The properties investigated were linearity, reproducibility, dose rate dependence, energy and linear energy transfer (LET) dependence. The influence of detector thickness on the results of depth dose measurements was also demonstrated. A Markus parallel plate ionization chamber was used for reference dosimetry. Silicon diode and diamond detectors showed linearity at therapeutic dose level, reproducibility better than 1% (1sigma) and sensitivity variation with dose rate and proton energy.

Diamond↗
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↗
PubMed2000

[Anesthesia-analgesia with remifentanil. Instrumental, laboratory and clinical evaluations].

The option of analgesic anaesthesia without hypnotic was investigated in 13 patients, submitted to general, orthopedic or urologic surgery. Induction and maintenance of anaesthesia was performed with syringe-pump infusion of remifentanil 1-->2.2 mcg/kg/m and cisatrecurium, 0.2/air with FIO2 0.3; ecg monitoring, sieric level of ACTH were studied. "Slipping 8 channels patterns" were observed without spindless and K complexes; only in 2 patients N2O 50% can be used for increasing the depth of narcosys; ACTH levels increases only after remifentanil infusion stop.

Adrenocorticotropic Hormone↗
PubMed1999

Sequence of metabolic changes during X-ray-induced apoptosis.

A cell population undergoing apoptosis usually contains varying proportions of cells in the diverse stages of the process, from very early continuously through to secondary necrosis. This heterogeneity acts as a confounding factor in metabolic studies if a general population is investigated. Using fluorescent probes and multiparameter flow cytometry, we report on metabolic changes occurring during X-ray-induced apoptosis in human peripheral blood lymphocytes and relate the observed alterations to cells at various phases of the process assessed by monitoring the progressive loss of selective plasma membrane permeability. Data show that alterations of mitochondria cardiolipin and a reduction of plasma membrane potential are rather early events as they commence in cells which still possess an impermeable plasma membrane. Conversely, mitochondrial transmembrane potential is impaired only when plasma membrane permeability starts to be altered, that is, in relatively later apoptotic cells, thereby reflecting the complexity of mitochondria demise during apoptosis. The prooxidant/antioxidant balance is altered in cells in early apoptosis with a correlated increase of prooxidants and depletion of thiols, the latter indicative for the progressive impairment of this detoxifying mechanism. The imbalance in prooxidant/antioxidant remained evident through apoptosis suggesting that oxidative damage starts early and then continues, eventually leading to cellular disruption. Assessing cell transit through the apoptotic process and coupling the observed metabolic changes to selected stages of the process enables one to improve the understanding of the temporary sequence of biochemical phenomena occurring in a given model.

Antioxidants↗