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E Pedroni

Publications and source records attributed to E Pedroni.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Risk factors of coronary graft disease following heart transplantation in children].

Coronary disease after cardiac transplantation is a major medium and long-term complication in adult patients. In childhood, this is reputed to be rare and, therefore, the authors undertook a study to evaluate its incidence and the role of potential risk factors in this age group. The study included 30 children followed up at least one year after cardiac transplantation and investigated by at least one selective coronary angiography after the first postoperative year. Seventeen patients (57%) had a normal coronary angiography but 13 had coronary lesions (43%). The two groups were compared for age, sex, HLA groups of the donor-recipient couple, the duration of ischaemia of the transplants, cytomegalovirus serology, lipid profile, number of episodes of acute rejection that were treated, the necessity for steroid therapy for more than 3 months, and the blood pressure. The only significant differences, probably inter-related, were the number of rejections treated, greater in the group with coronary lesions (2.23 +/- 1.01 per patient) than in the group with normal coronary arteries (1.53 +/- 1.01 per patient) (p < 0.05) and the necessity of triple therapy with addition of prednisone, greater in the first group (9/13) than in the second (4/17) (p < 0.02). These results show that coronary disease after cardiac transplantation is as common and as early in children as in adults. They strongly suggest an important role of immunological factors. On the other hand, the authors' experience did not confirm the role of other potential risk factors.

Adolescent↗
PubMed1993

The RBE of negative pions in the treatment of tumors with different volumes.

For negative pions, large differences exist between experimental RBE values obtained by in vivo investigations with animals and corresponding data being used in clinical tumor therapy. Therefore, the influence of the treatment volume on the radiation quality and respectively on the RBE is examined. The RBE for euoxic mammalian cells is measured with high precision in different volumes irradiated in the spot-scan mode with the PIOTRON at the Paul Scherrer Institute. It is shown experimentally that the RBE is reduced if the radius of the irradiation volume is increased. Using a simple mathematical approximation for the spot-scan technique this relation can be understood quantitatively. The same approximation is also used to calculate dose mean values for the lineal energy yD present in different irradiated volumes. The good agreement with existing experimental data for yD indicates that the approximation used is adequate and the main physical parameters have been taken into consideration. The above mentioned differences between animal experiments and treatment of patients can be explained by changes in the effective radiation quality due to the scanning procedure used in the clinical treatments.

Animals↗
PubMed1992

Conformal radiotherapy for unresectable retroperitoneal soft tissue sarcoma.

Local tumor control remains a continuing challenge in the treatment of retroperitoneal soft tissue sarcoma. Though complete resection by means of wide excision or excisional biopsy can be performed in a minority of patients only, aggressive surgical approach remains the treatment of choice. Unresectable sarcoma can rarely be controlled by conventionally applied radiotherapy--only a few percent of patients survive. A superior dose distribution of external radiation is demanded in order to spare healthy tissue. The presumably greatest advantage will occur when radiotherapy is used preoperatively. The possible clinical gain of superior dose distribution is demonstrated by results of the dynamic, 3-D conformal pion radiotherapy at PSI. Between April 1983 and June 1988 a total of 21 patients were treated with high doses (greater than or equal to 30 Gy) for unresectable retroperitoneal soft tissue sarcoma. The follow-up time is 13-74 months, median 24. Fifteen patients were treated with 20 fx, and 19 patients were treated with fraction sizes of 150 or 165 cGy. Except for one patient with thrombocytopenia after chemotherapy, no treatment interruption was necessary. Five patients developed late reactions, caused also by surgery and chemotherapy: two intestinal obstructions, one liver abscess, one leg edema, and one superficial skin necrosis. Nine patients had laparotomy after pion irradiation, five for resection of the previous unresectable tumor; 3/5 sarcoma were completely resected. Morbidity rate after post-pion laparotomy did not increase. Three patients had local tumor progression, 1/3 inside the treatment volume. The actuarial five-year local tumor control rate of these unresectable retroperitoneal sarcoma is 60%, the actuarial five-year survival rate is 33%. Out of the 21 patients, 15 are alive, two have died from local progression, one from peritoneal progression, and three from metastases.

Humans↗
PubMed1992

Effects of respiratory motion on dose uniformity with a charged particle scanning method.

A three-dimensional spot-scanning technique for radiotherapy with protons is being developed at the Paul Scherrer Institute. As part of the effort to optimize the design and ensure clinically useful dose distributions, a computer simulation of the dose deposition in the presence of respiratory motion was performed. Preliminary experiments have characterized the proton beam and the scanning procedure. Using these parameters, the computer program calculated the dose within a uniform volume of water in the presence of respiratory motion. Respiration amplitude, respiration period, respiration direction, number of fractions, size and position of the beamspots and rescanning multiplicity were systematically varied and the effect on the dose distribution determined. The dose uniformity is very dependent on the direction of the respiration relative to the three independent beam scanning directions. The dose uniformity decreases with increasing respiration amplitude, but has little response to changes in respiration frequency. Rescanning the volume, such as with fractionation, improves the dose uniformity roughly as the square root of the number of fractions. Broad, Gaussian beams result in better dose uniformity than narrow, sharply delineated ones, but produce slower dose fall-off at the edges of the scanned volume. Results of this work are being incorporated into the design of the system.

Computer Simulation↗
PubMed1991

Long term survival after heart transplantation for doxorubicin induced cardiomyopathy.

A 10 year old child developed severe cardiomyopathy after combined, multicycle chemotherapy for Ewing's sarcoma and was treated by heart transplantation with good results. Long term azathioprine and cyclosporin caused only mild impairment of immune function and there were no recurrent infections, local recurrences of the tumour, or distant metastases.

Cardiomyopathy, Dilated↗
PubMed1990

[Double discordance with ventricular septal defect and pulmonary artery hypertension. A study of 21 cases].

This paper reports a retrospective study of 21 children with atrioventricular and ventriculo-arterial discordance, or double discordance, associated with a large ventricular septal defect responsible for pulmonary hypertension. Other associated congenital defects were: atrioventricular block (5 cases), coarctation of the aorta with neonatal cardiac failure (6 cases), tricuspid valve malformations responsible for significant tricuspid regurgitation (11 cases) and right ventricular hypoplasia (1 case). Two children died before any therapeutic intervention, one from syncope related to atrioventricular block and the other after a decision of therapeutic abstention. Three children underwent total correction with one good result (the only case of situs inversus), one late death and one lost to follow-up. The majority of patients (n = 16) underwent initial palliative surgery consisting in pulmonary artery banding occasionally associated with reconstruction of the aortic arch: there was no early mortality but there were 2 late deaths. Of the 14 survivors, 6 are well after a mean follow-up period of 31 months. Eight underwent open heart surgery with 1 operative death, 6 post-operative complete atrioventricular blocks requiring cardiac pacing and 5 poor results due to aggravation or secondary tricuspid regurgitation leading to 1 cardiac transplantation (death) and 2 reoperations for valvular surgery (1 plasty and 1 tricuspid valve replacement). The overall results of this series are poor: high mortality (33 per cent) and equally high morbidity when direct surgery is undertaken. Two major complications are observed: complete atrioventricular block (55 per cent) and regurgitation of the systemic atrioventricular valve (45 per cent), both of which often necessitate invalidating complementary procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1990

Spot scanning for 250 MeV protons.

Protons have a long tradition in precision treatment of lesions of limited size at limited depth. Recently interest has developed in hospital based proton therapy accelerators, able to treat deep seated tumors. Heavy charged particles, and especially protons, are particularly suited to treat well localized tumors. Protons can be collimated as precisely as photons, but in addition have a well defined range. Protons are therefore predestinated for conformation radiotherapy also for larger target volumes. At the Swiss Institute for Nuclear Research a computer optimized treatment planning system has been developed for pion radiotherapy. The principle of this dynamic treatment technique can be adapted for proton therapy. It could prove to be a valid alternative to passive scattering for proton treatment especially of large irregularly shaped volumes. Dose calculations have been performed for specific cases using a 250 MeV pencil beam. The dose distributions and dose volume histograms have been compared with pion therapy. A horizontal experimental beam line, using a degraded 590 MeV proton beam of the PSI ring cyclotron, is set up to verify calculations in phantoms.

Humans↗
PubMed1989

Dynamic pion irradiation of unresectable soft tissue sarcomas.

Since November 1981, when pion irradiation was introduced for deep seated tumors at the Swiss Institute for Nuclear Research (SIN, now Paul Scherrer Institute, PSI) a dynamic, 3-dimensional spot scan treatment technique has been in use. To exploit this technique a special optimization treatment planning system has been designed. Of a total of 331 patients treated with pions from November 1981-December 1987, 35 were irradiated for unresectable soft tissue sarcomas. In 32/35 patients, tumor sites were retroperitoneal, pelvic or in the groin or thigh. Twenty-nine tumors had a maximum diameter of greater than 10 cm, 18 tumors of greater than 15 cm; 30 tumors had grade 2/3 and 32 Stage III B/IV A/IV B. Eight of 35 patients received a low pion total dose, 7-27 Gy. Twenty-seven patients received a total dose of 30-36 Gy, fraction size 150-170 cGy (90%-isodose), 20 fractions, 4 times per week. Of these 27 patients, severe late reactions appeared in five: 2/8 patients with extremity/groin sarcomas (1/2 caused by biopsy) and 3/19 patients with retroperitoneal/pelvic sarcomas (one a skin reaction after Actinomycin-D, one a small bowel reaction after 36 Gy, a dose no longer used). Seven of 27 patients had metastases at the beginning of irradiation. Three of 27 were treated with excisional biopsy, 9 with incisional biopsy or partial resection and in 15 patients biopsies were performed for histology only. The median follow-up of these 27 patients was 17 months (5-66). There was no progression in eight extremity/groin tumors but in 4 of 19 retroperitoneal/pelvic tumors. Three of these were marginal progressions. The actuarial 5-year rate of local tumor control is 64%; the actuarial 5-year survival rate of patients without metastases at the beginning of treatment is 58%. Dynamic spot scan pion irradiation proves to be a successful treatment technique for unresectable sarcomas with a high rate of tumor control and a very low rate of severe late reactions.

Adult↗
PubMed1989

[Aptitude for sports in children operated on for aortic coarctation. Contribution of the exercise test].

Pronouncing on the fitness of children operated upon for coarctation of the aorta to practise sports, as well as on the nature and level of this activity, depends, to a great extent, upon their blood pressure profile at exercise (BPE) as measured by an exercise test on an ergometric bicycle. We studied thi profile in 43 children aged 11.7 +/- 2.5 years who had undergone surgery for coarctation of the aorta (isolated in 93 p. 100 of the cases) at the age of 3.8 +/- 3.2 years Systolic arterial pressure (SAP) in the upper limbs was normal at rest in 80p. 100 of the children but reached abnormal values at exercise in 81 p. 100 and even exceeded 200 mmHg in 16 p. 100. Diastolic arterial pressure (DAP) in the upper limbs was sometimes slightly elevated at rest, but it clearly decreased at exercise and became normal in all cases. This suggested that systolic hypertension at exercise was due to low peripheral resistance and either to an exercise-induced isthmic gradient or to a poor vascular impedance. As a result of this study, we warn such children against playing sports with a strong static stress (e.g. martial sports) or with a risk of thoracic trauma (e.g. rugby). For the other sports, we make no reservation when the BPE is normal, and we forbid competitions when the BPE is abnormal but the SAP at exercise remains below 200 mmHg. Beyond this value, children must be investigated for residual coarctation of the aorta which may be amenable to a specific treatment.

Adolescent↗
PubMed1988

Cell-mediated cytotoxicity in Down syndrome: impairment of allogeneic mixed lymphocyte reaction, NK and NK-like activities.

Peripheral blood mononuclear cells (PBMC) from 16 non-institutionalized patients with Down syndrome (DS) were studied with various monoclonal antibodies and analysed for natural killer (NK), and NK-like activity. Lymphocyte proliferation and cytotoxic T-lymphocyte (CTL) cytotoxicity generated in mixed lymphocyte culture (MLC) were also evaluated in 11 DS patients. Phenotypic characterization of PBMC from DS subjects confirms our previous findings of high numbers of CD8+ lymphocytes and HNK-1+, and CD16+ cells. Lymphocyte proliferation and CTL cytotoxicity generated in MLC were low or absent in most patients. NK activity was low in almost all DS patients, while NK-like cytotoxicity generated in MLC was normal in the majority and did not correlate with NK activity from unstimulated PBMC.

Adolescent↗
PubMed1988

An intercomparison of two dynamic treatment techniques, ring scan and spot scan, for head and neck tumors with the Piotron.

An evaluation of the ring scan and the spot scan was made for the pion irradiation of head and neck tumors with the Piotron. For the geometry of the Piotron, with its 60 radially converging beams, two scanning techniques have been developed, ring scan and spot scan. They have different characteristics concerning achievable dose distributions and sensitivity to tissue inhomogenities. The optimized 3-dimensional dose distributions for the treatment with ring scan and spot scan techniques were calculated for two examples of the target volume. The comparison of the dose distributions has shown that the ring scan is better in sparing normal tissues than the spot scan for a simple shape target volume but not for an irregular shape target volume with the present status of the technique. The irradiation time needed for the ring scan is longer, for the present examples three times, than for the spot scan. From the practical view point the spot scan is preferable to the ring scan for the treatment of head and neck tumors with the Piotron.

Elementary Particles↗
PubMed1988

Anomalous left coronary artery arising from the pulmonary artery in infancy: is early operation better?

From January 1975 to January 1987, 21 consecutive infants aged less than six months (mean (SD) 2.6 (1.2] were admitted with anomalous origin of the left coronary artery from the pulmonary artery. In the first 12 patients, who were seen up to 1982, operation was performed after the age of one year (mean (SD) 29 (29) months) (group 1). The next nine infants, seen from 1983 to 1987, had their operations within a few weeks of the onset of symptoms (mean (SD) age 4.8 (1.4) months) (group 2). In group 2 the left coronary artery was relocated into the aorta, whereas in group 1 there was additional resection of the left ventricular wall or mitral valvoplasty or both. At presentation there were no differences in age, clinical condition, heart enlargement, and echocardiographic left ventricular dysfunction between groups 1 and 2. Seven of the 12 patients in group 1 died, five while they were awaiting operation (three died suddenly at home) and two at operation. The five survivors are doing well 6.4 (3.1) years after operation with normal left ventricular function which improved slowly over several months after operation. Two of the nine patients in group 2 died; both deaths occurred at or soon after operation. The seven survivors are doing well 1.8 (0.9) years after operation. In three, left ventricular function recovered within three weeks; and there was even partial or total regression of the Q waves in the supposedly necrotic areas. In the remaining four the pattern of improvement in left ventricular function resembled that in group 1. Operation should be undertaken early in infants with anomalous left coronary artery arising from the pulmonary artery because the procedure is relatively safe, prevents a high natural mortality, and offers a better chance of a faster recovery of left ventricular function.

Age Factors↗
PubMed1988

Fate of pulmonary artery after anatomic correction of simple transposition of great arteries in newborn infants.

From April 1984 to April 1987, surgical anatomic correction was performed in 86 newborn infants, 2-23 days old (6.8 +/- 3.6 days, mean +/- SD) with simple transposition of the great arteries. In all patients, the pulmonary artery was reconstructed by end-to-end anastomosis according to the Lecompte maneuver, including eight patients with side-by-side position of the great arteries. Three different approaches were used. In the first 10 patients (group 1, six survivors), two separate patches of preserved tanned pericardium were used to reconstruct the pulmonary artery, whereas in the next 15 patients (group 2, 13 survivors), a single patch of the same material was used, and in the last 61 patients (group 3, 56 survivors), surgery was performed with a single patch of fresh autologous pericardium. Among the 75 survivors, 68 (including six in group 1, 12 in group 2, and 50 in group 3) were followed serially for at least 6 months (6-48 months, 26 +/- 9 months) with sequential noninvasive evaluations. At follow-up, all were asymptomatic with normal growth. Two patients with severe pulmonary artery stenosis (group 1) were successfully reoperated on. Four infants with moderate pulmonary artery stenosis have been followed medically and have had stable right ventricular pressures. The last 62 patients have normal or near-normal right ventricular pressures. The spatial relation of the great arteries did not affect the quality of the results. Group 1 had clearly the worst results.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1988

[Development of aortic valve stenosis in infants and children. Apropos of 66 cases hospitalized from 1973 to 1984].

Sixty-six children aged over 6 months hospitalized for isolated aortic valve stenosis without cardiac failure but with a transvalvar systolic pressure gradient of more than 40 mmHg were followed up and re-evaluated for a mean period of 5.4 +/- 3.5 years. Twenty-two children who were asymptomatic, had no ST-T changes and had a less than 60 mmHg gradient were not operated upon; they remained stable over a mean period of 5.4 +/- 3.4 years; their gradient was not significantly modified (53 instead of 51 mmHg) and none of them underwent surgery. Forty-four children with symptoms and/or a more than 60 mmHg gradient underwent valvotomy under extracorporeal circulation without mortality. Surgery was effective against the major symptoms in all cases, and it reduced the gradient from 75 +/- 25 to 36 +/- 18 mmHg at the expense of aortic regurgitation in 7 cases, 2 of them with significant haemodynamic repercussions. During the follow-up period (5.8 +/- 3.7 years) 1 patient died of bacterial endocarditis, 5 were reoperated upon (with prosthesis in 4) without mortality and with 4 good results, and 1 patient underwent valvoplasty which proved partially effective but resulted in moderate aortic regurgitation. All other children are now doing well; 29 are completely asymptomatic and without ST-T changes at rest or during exercise. We conclude that aortic valve stenoses with moderate gradient are very stable at mid-term and that surgical valvotomy is a generally effective and low-risk procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗