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Biomedical subjects

P Sandri

Publications and source records attributed to P Sandri.

15 recordsLinked to original sources
PubMed2003

Tunneling as a stochastic process: a path-integral model for microwave experiments.

Delay time results obtained in microwave experiments at frequencies above and below the cutoff frequency of different waveguide sections are interpreted on the basis of wave propagation in the presence of dissipative effects. Kac's original suggestion was the starting point for the formulation of a stochastic model, which has now been substantially improved, also in relation to the transition-elements theory of Feynman-Hibbs. In this way, an approach to the problem is provided, which is completely distinct from the ones formulated elsewhere.

Journal Article↗
PubMed2002

Anomalous delay in wave propagation and tunneling: a transition-elements analysis of the traversal time.

An alternative model for near-field propagation and optical tunneling is proposed following the lines of the path-integral method developed by Feynman, and in particular by using a transition-elements analysis. Such a model was able to account for the frequency dependency of delay-time results of an experiment involving microwave propagation in the near field using two horn antennas [A. Ranfagni et al., Phys. Rev. E 66, 036111 (2002)]. Furthermore, this approach is also capable of interpreting delay-time results as a function of the barrier width in a frustrated total internal reflection experiment performed at the microwave scale and in the optical region.

Journal Article↗
PubMed2002

Anomalous pulse delay in microwave propagation: A stochastic process interpretation.

An experiment involving microwave propagation in the near-field region with two horn antennas demonstrated a superluminal behavior which is strongly dependent on the frequency. The models previously proposed are found to be inadequate for interpreting the results. An attempt is made within the framework of a stochastic model, which can be improved by a path-integral analysis.

Journal Article↗
PubMed2002

Simple stochastic model for optical tunneling.

A simple model, derived from a Brownian-motion scheme, is capable of interpreting the results of delay-time measurements relative to frustrated total reflection experiments at the microwave scale but also in the visible region. In this framework we also obtain a plausible description of the trajectories (rays) inside the tunneling region, the air gap between two paraffin prisms.

Journal Article↗
PubMed2001

Experimental evidence of tunneling as a stochastic process.

A model for tunneling based on stochastic processes proves to be capable of interpreting the results of two experiments at the microwave scale. The first of these consisted of measuring the penetration time in a subcutoff waveguide; the second one, in measuring the shift of a beam in a frustrated total reflection. Said shift which is a measurement of the traversal time of the barrier. In both cases, a peak in the real-time component was evidenced, as predicted by the theoretical model.

Journal Article↗
PubMed1998

A double blind randomized study of oral clodronate in the treatment of bone metastases from tumors poorly responsive to chemotherapy.

Bisphosphonates are used in oncology as a means of decreasing complications due to bone metastases, in association with anticancer treatment, especially in patients with breast cancer, prostate cancer and myeloma. Little is known about the effects of bisphosphonates on bone metastases from other tumors and in particular from tumors for which no effective treatment is available. We conducted a randomized, double-blind placebo-controlled trial of oral clodronate in patients with bone metastases from tumors poorly responsive to chemotherapy, with the aims of evaluating the effects of this drug on symptoms control and bone metastases evolution. Sixty-six patients with poorly responsive tumors such as non-small cell lung cancer (NSCLC), bladder cancer, gastrointestinal cancers, kidney cancer, melanoma and metastatic carcinoma of unknown origin entered the study. Patients were randomized to receive either clodronate 1,600 mg/day for one year or identical placebo-containing tablets. Various parameters such as Karnofsky performance status, pain score (measured by a visual-analogue scale) and analgesic requirement were recorded at monthly intervals. Of the 66 patients enrolled, 9 were observed for one month or less; 7 were followed for two months; only 50 patients were followed for more than 2 months and could be adequately evaluated. At 3 months both clodronate and placebo-treated patients had a decrease in Karnofsky performance status, with the decrease being more evident in the placebo group. Mean pain scores showed an increase of pain in patients receiving placebo and a decrease of pain in patients receiving clodronate, although the difference failed to be statistically significant. Analgesics requirement increased in both groups, but significantly more in patients receiving placebo (p = 0.042), in whom increase in opioid requirements was particularly evident. Toxicity was low, with occasional gastroenteric discomfort in both groups. The main problem of this study was the difficulty in recruiting an adequate number of patients and following them for a sufficient period of time: general conditions rapidly deteriorated in many patients, and approximately 25% of the 66 enrolled were not considered evaluable; few patients survived for the length of the study, one year. This might partly account for the lack of significance of some of the parameters under study. With these limits, oral clodronate demonstrated some efficacy in symptom control and in reducing the need for analgesics.

Administration, Oral↗
PubMed1997

[The radiological exam of the chest in the elderly. Technical and methodological considerations].

PURPOSE: We investigated the capabilities of chest radiography in the elderly considering that the examination must meet the main clinical indications of this population and that it is necessary in the elderly because the correct clinical assessment is often difficult or impossible. MATERIALS AND METHODS: We reviewed the chest radiographs of 756 consecutive elderly patients admitted to our hospital from September 1 to October 31, 1996. If possible, chest radiographs were performed with the AMBER technique (156 patients, 20.7%); 240 patients (31.7%) underwent conventional radiography and the others frontal projections only (360 patients, 47.6%). T-MAT G RA Kodak high contrast films with Kodak Lanex green transmitting intensifying screens were used in all cases. The AMBER examinations of 48/156 patients with hemodynamic clinical indications were repeated with conventional frontal projections. Radiographic reports were made separately by different radiologists who considered especially the diagnostic accuracy of every examination in determining the venous overload of pulmonary circulation. RESULTS: Hemodynamic studies are the most frequent clinical indication of chest radiography in elderly patients (228/756 patients in our series, 30.2%); moreover, even if careful cardiac and pulmonary circulation studies are very important in these patients, only 52.4% of all radiographs could be made in two orthogonal projections. The blurred appearance of vascular landmarks indicating increased extravascular fluid is better depicted by conventional radiography (59.7% of cases) than by AMBER (40.3%). CONCLUSIONS: We conclude that the reduced pulmonary contrast obtained with the so-called "hard X-ray" technique poorly depicts the blurred appearance of pulmonary vessels in pulmonary venous overload. Moreover, "hard X-ray" techniques can be only sporadically used because elderly patients are often in very critical conditions, which prevents this type of examination.

Aged↗
PubMed1992

[Chemoembolization in the therapy of hepatocarcinoma. A 3-year experience].

This study was aimed at evaluating the efficacy of chemoembolization (CE) to improve survival in patients with hepatocellular carcinoma (HCC). Our results were compared with the natural history of HCC. Sixty-two consecutive patients with HCC in Okuda's stages I and II underwent CE. Forty-seven patients were treated with CE alone; 9 patients had CE prior to surgery, and 6 patients had it after surgery because of recurrent HCC. One hundred and nine CEs (mean: 1.8 CEs/patient) were performed with Lipiodol UF, epirubicin and gelatin sponge. Actuarial survival was calculated considering Okuda's stage, neoplasm size, and evidence of pseudocapsule. The mean cumulative survival of the 47 patients treated with CE alone was 13.2 months; survival (+/- SE) at 12, 24 and 36 months was 0.75 (+/- 0.07), 0.46 (+/- 0.10) and 0.28 (+/- 0.12). Survival was not affected by Okuda's stage, neoplasm size, evidence of pseudocapsule (p > 0.05). Nevertheless, the patients with early HCC had better prognosis. Eighteen patients (42.9%) died during follow-up, 12 of whom (66.7%) from hepatic failure. The mean survival of patients with recurrence of HCC after surgery was 41 months (range: 24.8-74.9 months) since initial diagnosis of HCC, and 14.8 months (range: 7.1-29.6 months) since diagnosis of recurrence. Two of these patients died from hepatic failure. All the patients who underwent also surgery after CE are still alive (mean survival: 14.7 months). Histologic findings of resected specimens revealed viable neoplastic cells in all cases. Twenty-one major complications (20.2%) occurred in 18 patients (29%); the outcome of complications was favorable in all but one patient who died from sepsis. CE is a reliable and safe treatment for unresectable HCC. Small HCCs should be preferably treated with surgery or, alternatively, with percutaneous alcohol injection.

Aged↗
PubMed1985

Palliative cryosurgery for oral cavity malignant melanoma: a case report.

A case of unresectable malignant melanoma of the oral cavity, treated with cryosurgery, is reported. A complete remission of 10 months was obtained, followed by 2 local recurrences, both treated successfully (CR: 9 and 4 months). At 23 months after the first treatment, a new local recurrence was considered untreatable.

Aged↗
PubMed1984

Telethermography and axillary node status as predictors of early relapse in breast cancer: preliminary report.

The authors report on 141 primary, non-metastatic, breast cancer patients with a minimum follow-up of 12 months after surgery to a maximum of 5 years. All cases were studied according to the patterns of the preoperative telethermography (TH) and nodal status (N). Prognosis was evaluated in terms of incidence of relapse. A statistically significant correlation was found between TH+ and early relapse, and for N+, but there was no correlation between TH and N, both for negative and positive values. The results suggest a complementary prognostic value of the two parameters.

Breast Neoplasms↗
PubMedDate not supplied

[Management of breast cancer in geriatric age; observations on 164 cases].

Progressive increasing of the life expectancy and the ever more frequent finding of breast cancer in elderly women have focused the attention on the treatment of this pathology in the elderly women. Today most studies support a more aggressive locoregional and systemic therapy in older patients in good physical condition. Authors analyze retrospectively a series of 164 women with breast cancer aged over 69 years treated with combined modality therapy regarding the stage of disease and the status of the patient. Survival by stage, tumor characteristics, node involvement have been compared with a series of patients less than 70 years treated on the same period. Survival curves were not significantly different between the two groups, except for T1 which showed a better survival in younger patients. Also survival according to node involvement did not show significant differences between the two groups. in conclusion, older women should be treated with the same surgical procedures, according to stage, of the younger patients, if they are not too frail to undergo surgery. Only the definitive results of prospective randomized trials will better define the indications and limits of a further reduction of the extent of surgical excision.

Age Factors↗
PubMedDate not supplied

The combination of metoclopramide, methylprednisolone and ondansetron against antiblastic-delayed emesis: a randomised phase II study.

The aim of the study was to verify whether the combination of an antiserotoninergic, metoclopramide, and a steroid could improve the complete control (CC) of delayed emesis, a contraversial issue, 105 patients undergoing highly-emetogenic chemotherapy, receiving Ondansetron (O) 8 mg + Dexamethasone 20 mg i.v. for the prevention of acute emesis, were randomly treated p.o for three further days with a) Metoclopramide 10 mg x 3 b) the same as a) + Methylprednisolone 4 mg c) the same as b) + O 8 mg x 3. CC (acute+delayed emesis) over three cycles was: a) 0.b) 12.5%, c) 38.5% (p = 0.02). Days with nausea/vomiting: 59%, 51%, 29.7% of the total observed period, respectively (b vs c p = 0.0000). CC of acute emesis was similar in the first cycle (about 85%), remained unchanged in the following cycles (c) and decreased to 30% and 68% in the third cycle (a and b) (p = 0.01). The three drug combination significantly improved complete control of acute and delayed emesis over successive chemotherapy cycles.

Adult↗
PubMedDate not supplied

[Effectiveness of sequential administration of G-CSF and GM-CSF after antineoplastic chemotherapy in patients with advanced tumors: results of a randomized trial].

Recent in vitro data have shown that growth factors are more effective when used in combination. This synergy between cytokines, when translated in a clinical setting, should permit a reduction of dosage, and therefore of toxicity. We sought to determine whether the sequential administration of low doses of G-CSF followed by low doses of GM-CSF could be effective both in protecting from neutropenia, and in reducing side effects. A randomized single blind phase III study was carried out. Patients considered to be eligible for the study were designated to receive a minimum of 3 chemotherapy cycles for treatment of metastatic or locally advanced cancer. Patients were randomized to receive, from the 8th day to the 13th day of cycle, G-CSF, 2.5 micrograms/kg/day s.c., or G-CSF, 2.5 micrograms/kg/day s.c. for the first 3 days, followed by GM-CSF, 2.5 micrograms/kg/day s.c. for the last 3 days. The number of delays in relation to the number of cycles, the number of patients whose therapies were deferred, and the total number of days of delay in relation to the total number of days of observation were significantly different, with far fewer delays in the group treated with the G-GM sequence. Our study confirms that the sequential administration of G-CSF and GM-CSF is highly synergistic. This synergy allows clinicians to administer chemotherapy treatments to pre-treated and/or elderly patients, with minimal risk of toxicity and no need for delays or dosage reduction.

Adult↗