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Biomedical subjects

M Pedrini

Publications and source records attributed to M Pedrini.

8 recordsLinked to original sources
PubMed2006

Comparison of dose distributions in IMRT planning using the gamma function.

Intensity-modulated radiotherapy (IMRT) (1) is an advanced form of 3-D conformal radiotherapy. It uses non uniform spatial modifications in the intensity of the beams across the irradiated field. Consequently, it is necessary to develop sophisticated tools to compare measured and calculated dose distributions in order to verify the accuracy of the results of the planned dose distribution. Different methods have been developed to evaluate the accordance between measured and calculated doses, such as the point-to-point dose difference or the evaluation of the distance between two closed points having the same dose value (2-4). The verification method proposed by Low (5-7) seems to be more complete since it takes into account both the dose difference (DD) and the distance to agreement (DTA), allowing to define a "score", the gamma value, at each point of interest. A software tool (DDE: Dose Distribution Evaluator), based on Low's method, to evaluate the agreement between dose distribution matrices has been implemented. In particular, the proposed gamma curve, as a function of the isodose levels, gives real-time information useful for decision making about the treatment plan. The paper describes the software, and reports the obtained results in a simple geometry and in several clinical cases (head-neck and prostate). Comparison between measured data (film and MapCheck) and calculated data (CadPlan) using DDE has shown very good agreements. Thanks to its higher resolution, film dosimetry showed better accuracy than the MapCheck technique. Similar results can be obtained also with the MapCheck technique when proper measurement methods are used.

Dose-Response Relationship, Radiation↗
PubMed1992

Tissue-specific pattern of nonhistone high mobility group proteins in various organs of the chicken.

Electrophoretic analysis of tissue-specific differences of nonhistone high mobility group (HMG) proteins from nuclei of various organs of the chicken revealed that in organs with a higher proportion of replicating cells (thymus, Bursa Fabricii, spleen) the relative amount of HMG-17 is considerably higher than that of HMG-14; however, in transcriptionally active organs with a very small proportion of replicating cells (glandular stomach, liver) HMG-14 and HMG-17 are present at roughly equal and low amounts. In glandular stomach, liver and spleen, the relative contents of both HMG-1 and HMG-2 are markedly lower than in thymus and Bursa Fabricii. Moreover, the total amount of HMG proteins is higher in those organs which contain replicating lymphocytes.

Animals↗
PubMed1990

Suitability of staining techniques for the detection and quantitation of nonhistone high mobility group proteins.

Three different staining techniques were compared for the detection of nonhistone high mobility group (HMG) proteins after acidic urea-polyacrylamide gel electrophoresis. Silver staining after glutaraldehyde fixation provides the highest detection sensitivity. Because of the acid solubility of HMG proteins special care has to be taken concerning fixation. Staining with colloidal CBB G-250 according to Neuhoff et al. is superior in sensitivity and reliability of quantitation when compared with noncolloidal Coomassie Brilliant Blue R-250. High detection sensitivity and reproducibility of quantitation are prerequisites for studying the tissue-specific expression of HMG proteins. In the present study tissue-specific differences in the molar amounts of various HMG proteins in thymus and erythrocytes of the chicken are documented by application of the methods tested.

Animals↗
PubMed1986

Tetralogy of Fallot with subarterial ventricular septal defect. Diagnostic and surgical considerations.

Since 1964, 77 patients underwent repair for tetralogy of Fallot with subarterial ventricular septal defect. Median age at operation was 5 years. Cyanosis was commonly mild, and hypoxic episodes were infrequent. Accordingly, only 12 patients (15.58%) needed either palliative or corrective operations before the age of 2 years. Characteristic angiographic and echocardiographic features were observed, which allowed this entity to be differentiated from either classic tetralogy or other types of double-outlet right ventricle. The earliest series of operations (in which no right ventricular outflow patch was used) was followed by a prohibitive mortality (50%). Residual subpulmonary obstruction was the cause of all of these deaths. In a second series of patients, a transannular patch was frequently used (79.59%), with the rationale that closure of the ventricular septal defect would make restrictive the deficient infundibulum of these patients. In a later series, we observed that most of the patients had a nonrestrictive pulmonary anulus (80%); the patch therefore was limited to the ventriculotomy. In the absence of pulmonary annular hypoplasia, the need for patching of the right ventricular outflow tract in this entity has to be confined to preventing the subpulmonary obstruction induced by closure of the ventricular septal defect. A considerable improvement in the results followed our first series (4.3% mortality). Follow-up of the survivors (mean 7 years) has been satisfactory.

Child, Preschool↗
PubMed1978

Tetralogy of Fallot with subpulmonary ventricular septal defect.

Among a total of 608 patients with tetralogy of Fallot, 35 with tetralogy and subpulmonary ventricular septal defect (VSD) have undergone intracardiac repair at the Children's Hospital, Buenos Aires. The crista supraventricular was absent in 62.9% of these patients; it was hypoplastic in 37.1%. Only 3 patients (8.6%) were severely cyanotic and required operation in infancy. The main and left and right pulmonary arteries were relatively large in all but 1 patient. Nevertheless, patch-graft enlargement across the pulmonary valve ring was necessary in 20 (57.1%). We believe that closure of the subpulmonary VSD increase the apparent severity of the pulmonary stenosis and necessitates patch-graft enlargement in patients in whom the appearance of the right ventricular outflow tract before repair would not have suggested its need.

Adolescent↗