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Biomedical subjects

L Pavesi

Publications and source records attributed to L Pavesi.

At least 19 recordsLinked to original sources
PubMed2001

Photoluminescence from (Si/SiO2)n superlattices and their use as emitters in [SiO2/Si]n SiO2 [Si/SiO2]m microcavities.

Si/SiO2 superlattices are recently under investigation to add optical functionality to silicon based microelectronics. In such superlattices quantum-confinement should drive Si to become a good light emitter. Emission properties can be further improved and controlled by placing the emitter in optical microcavities. In this paper emission properties of (Si/SiO2), superlattices grown by Low Pressure Chemical Vapour Deposition will be compared with the ones obtained by other growth techniques and the origin of the emission will be discussed. Emission properties can be further improved and controlled by placing the emitter in optical microcavities. Optical properties of microcavities produced with standard complementary metal-oxide-semiconductor techniques containing Si/SiO2 superlattices as light emitter will be reviewed and a comparison between properties estimated from calculations and experiments will be given.

Biophysical Phenomena↗
PubMed2001

Application and validation of a computerized cough acquisition system for objective monitoring of acute cough: a meta-analysis.

STUDY OBJECTIVE: The purpose of the meta-analysis was to understand the antitussive effect of treatment with dextromethorphan hydrobromide, 30 mg, vs placebo over a 3-h treatment period in patients with cough due to uncomplicated upper respiratory tract infection (URTI), and to show that the computerized system for acquisition and analysis of cough sound was consistent and reproducible across the individual studies. STUDY DESIGN: The six studies used for the meta-analysis were randomized, double-blind, parallel-group, single-dose, placebo-controlled studies with a 3-h postdose cough evaluation period. SETTING: One study was conducted in Durban, South Africa, and five studies were conducted in Bombay, India. Four studies took place in clinics, and two studies were in-home studies. PATIENTS: Seven hundred ten adult patients with cough due to uncomplicated URTI who were otherwise healthy and who satisfied the inclusion/exclusion criteria for the meta-analysis. MEASUREMENTS AND RESULTS: For each patient, a standard baseline was calculated pretreatment, then a 3-h continuous cough recording was made after treatment was initiated. Five efficacy variables were measured in 30-min intervals: cough bouts, cough components, cough effort, cough intensity, and cough latency. The meta-analysis showed consistent results across most of the studies for each of the efficacy variables. It demonstrated significantly greater overall reductions in cough bouts, cough components, and cough effort, and an increase in cough latency for patients treated with dextromethorphan hydrobromide, 30 mg, vs those treated with placebo. CONCLUSION: The results of a meta-analysis of the six clinical studies show that the antitussive effect of a single dose of dextromethorphan hydrobromide, 30 mg, has been established. The consistent nature of the results shows that the computerized cough acquisition and analysis system is a valid and reproducible methodology for evaluating cough associated with URTI.

Adolescent↗
PubMed2000

Optical gain in silicon nanocrystals.

Adding optical functionality to a silicon microelectronic chip is one of the most challenging problems of materials research. Silicon is an indirect-bandgap semiconductor and so is an inefficient emitter of light. For this reason, integration of optically functional elements with silicon microelectronic circuitry has largely been achieved through the use of direct-bandgap compound semiconductors. For optoelectronic applications, the key device is the light source--a laser. Compound semiconductor lasers exploit low-dimensional electronic systems, such as quantum wells and quantum dots, as the active optical amplifying medium. Here we demonstrate that light amplification is possible using silicon itself, in the form of quantum dots dispersed in a silicon dioxide matrix. Net optical gain is seen in both waveguide and transmission configurations, with the material gain being of the same order as that of direct-bandgap quantum dots. We explain the observations using a model based on population inversion of radiative states associated with the Si/SiO2 interface. These findings open a route to the fabrication of a silicon laser.

Journal Article↗
PubMed1998

Phase II study with ifosfamide, carboplatin, etoposide (ICE regimen) at intermediate dosage for advanced non small cell lung cancer (NSCLC).

We have evaluated the combination of ifosfamide, carboplatin and etoposide (ICE regimen) along with mesna in 26 previously untreated patients with non small cell lung cancer (NSCLC). Thirteen stage III B and 13 stage IV patients received intermediate doses of ifosfamide (1000 mg/m2), carboplatin (120 mg/m2) and etoposide (120 mg/m2) given intravenously on day 1 to 3 every 4 weeks. Except for one patient who experienced grade 3 transient thrombocytopenia no major events of hematological or systemic toxicity were observed. Response rate (27%, 95% C.I., 10 to 44%), median duration of response (9 months, range 6-15), and survival (9.5 months, range 2-44+) were comparable to those achieved with conventional cisplatin-containing regimens. Our ICE combination, as compared to standard or high dose schedules appears effective, safe, well tolerated, and devoid of severe hematological toxicity.

Adult↗
PubMed1998

Stem cell enumeration in cord blood vs bone marrow and peripheral blood.

Recent reports have suggested that the total number of autologous or allogeneic hematopoietic stem cell (HSC) infused after high-dose chemotherapy might predict survival, post-transplant morbidity and rate of hematopoietic engraftment. However, HSC capable of long-term multilineage potential are still poorly defined, and tools for accurate and reproducible HSC enumeration are highly warranted.

ADP-ribosyl Cyclase↗
PubMed1998

Autologous platelet transfusion in patients receiving high-dose chemotherapy and circulating progenitor cell transplantation for stage II/III breast cancer.

BACKGROUND AND OBJECTIVE: Concerns about the risk of transfusion therapy are driving towards new strategies which are designed to minimize exposure to allogeneic blood products. We aimed to find out whether it is possible to support the phase of thrombocytopenia following high-dose chemotherapy (HDC) and circulating progenitor cells (CPC) transplantation by autologous platelet concentrates (PC). DESIGN AND METHODS: PC were collected from 32 patients undergoing HDC and CPC transplantation for stage II/III breast cancer. A single plateletpheresis was performed at rebound after high-dose cyclophosphamide, when platelet count exceeded 250 x 10(9)/L. PC were cryopreserved in 5% DMSO after controlled-rate freezing and stored in liquid nitrogen. In vitro studies of cryopreserved platelets (aggregation, ATP release and change of mean platelet volume induced by EDTA) were performed. When platelet counts dropped below 20 x 10(9)/L following HDC (thiotepa 600 mg/m2, L-PAM 160 mg/m2) and CPC transplant (CD34+ cells > 5 x 10(6)/kg), PC were thawed in a 37 degrees C water bath, centrifuged to remove DMSO, resuspended in autologous plasma and reinfused within one hour. RESULTS: Large quantities of platelets were harvested in all patients (median 6.6 x 10(11), range 4.8-12.2). In vitro studies showed preserved platelet function as compared to both fresh platelets and standard PC. Twenty-eight out of 32 patients received autologous PC. At the time of transfusion most of the patients were febrile (> 38 degrees C) and had mucositis > G2. The median number of platelets reinfused was 3.8 x 10(11) (range 2.0-8.1) with a median loss during the freeze-thaw-wash procedure of 37%. Autotransfusion was able to maintain platelet count above 20 x 10(9)/L in most patients, with a corrected count increment > 7.5 in 20 cases. Four patients required one additional allogeneic transfusion, two because of a poor increment and two due to a late-occurring epistaxis. No side effects related to PC infusion were recorded. Sixteen control patients who received the same HDC and a similar number of CD34+ cells required a total of 17 allogeneic PC units (1 patient did not require platelet transfusion). INTERPRETATION AND CONCLUSIONS: Our data demonstrate that large doses of autologous platelets can easily be collected and safely administered to support the period of thrombocytopenia in patients undergoing HDC and CPC transplantation. Autologous PC in these patients can abrogate the risks deriving from allogeneic platelet transfusion.

Adult↗
PubMed1997

Multilineage long-term engraftment potential of drug-resistant hematopoietic progenitors.

Peripheral blood progenitor cells (PBPCs) are increasingly used instead of bone marrow for autologous or allogeneic transplantation. In this study PBPCs mobilized in cancer patients by chemotherapy and granulocyte-colony stimulating factor were collected by apheresis and first enriched by immunoaffinity removal of lineage positive cells. When these cells were exposed to both cyclophosphamide and taxol or cultured for 7 days in the presence of 5-fluorouracil, stem cell factor, and interleukin-3, 88% to 93% of the enriched PBPCs were killed and short-term clonogenic capacity in methylcellulose assays was lost, but week-5 cobblestone area-forming cell (CAFC) enrichment was higher than 10-fold in comparison to enriched PBPCs and higher than 700-fold in comparison to unmanipulated apheresis cells. After drug exposure, most of the progenitors displayed a CD34+, CD38-, multidrug-resistance (MDR+), Rhodamine 123 low, Hoechst 33342 low phenotype, and as few as 180 of these drug-resistant cells were able to generate a stable multilineage human hematopoiesis in sublethally irradiated immunodeficient mice. In these animals, the level of human hematopoietic engraftment was significantly increased by cotransplantation of irradiated cells from the human L87/4 stromal cell line. These observations are consistent with the functional isolation of a population of very early hematopoietic progenitors and might help to design new protocols for the removal of neoplastic cells from autografts.

Animals↗
PubMed1997

Collection of circulating progenitor cells after epirubicin, paclitaxel and filgrastim in patients with metastatic breast cancer.

The efficacy of high-dose chemotherapy (HDC) and circulating progenitor cell (CPC) transplantation in metastatic breast cancer (MBC) relies mainly on giving this treatment after a response to conventional induction chemotherapy has been achieved. For this reason an optimal mobilization regimen should be therapeutically effective while minimizing the number of leucaphereses required to support the myeloablative therapy. The combination of an anthracycline and paclitaxel in chemotherapy-untreated MBC has produced impressive response rates. We evaluated the CPC-mobilizing capacity of the combination epirubicin (90 mg m(-2)) and paclitaxel (135 mg m(-2)) followed by filgrastim (5 microg kg(-1) day(-1)) starting 48 h after chemotherapy administration in ten patients with MBC who were eligible for an HDC and CPC transplantation programme. Leucaphereses were performed by processing at least two blood volumes per procedure at recovery from neutrophil nadir when CD34+ cells in the peripheral blood exceeded 20 microl(-1). In most patients (six out of 10) more than 2.5 x 10(6) CD34+ cells kg(-1), a threshold considered to be sufficient for haematopoietic reconstitution, were collected with a single apheresis. In the remaining four patients an additional procedure, performed the following day, was enough to reach the required number of progenitors. These data suggest that the epirubicin-paclitaxel combination, besides being a very active regimen in MBC, is effective in releasing large amounts of progenitor cells into circulation.

Adult↗
PubMed1997

Role of tumor cells contaminating the graft in breast cancer recurrence after high-dose chemotherapy.

One of the possible drawbacks to autologous stem cell transplantation in breast cancer (BC) patients is the potential for tumor contamination in the transplanted product. We present a patient with advanced disease who received high-dose chemotherapy (HDC) and PBPC support as consolidation therapy after achieving complete remission with standard-dose first-line treatment, and suffered recurrence of the disease 6 months after transplantation. Retrospective analysis revealed the presence of contaminating cells in the leukapheretic product, and clinical evidence suggested a role for these cells in the tumor relapse.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

NMR study of the diffusion processes in gels.

Stimulated spin-echo and Carr-Purcell pulse sequences, with pulsed magnetic field gradients, have been used to study the self-diffusion processes of the water in swollen and in supercoiled polyacrylamide gels and in polysaccharides agarose gels, for different polymer concentrations. Restricted diffusion effects are evidenced in both types of gels through the time dependence of the diffusion constant. The results can be interpreted in the framework of diffusion model through permeable walls.

Acrylic Resins↗
PubMed1995

Pharmacokinetic evaluation of two different formulations of megestrol acetate in patients with advanced malignancies.

The bioequivalence of two megestrol acetate formulations, 160-mg "tablets" and 160-mg "sachets," was investigated in a single-dose, open-label, balanced-for-sequence cross-over study involving 12 advanced-cancer patients. The observed plasma megestrol-acetate time course obtained with both formulations was consistent with the literature data. The main source of variability in the pharmacokinetic parameters was intersubject variability; drug formulation played only a minor (and nonsignificant) role. The width of the 90% confidence interval of the area-under-the-curve (AUC) ratio (sachets: tablets) computed according to Schuirmann (0.9-1.4) was mainly due to the presence of a single outlier, showing an AUC ratio of 2.7. The trend to higher bioavailability of the new formulation was not significant, especially as compared with the dose-response data reported in the literature.

Administration, Oral↗
PubMed1994

Dose intensification of chemotherapy in advanced breast cancer: a feasibility phase II study.

AIMS AND BACKGROUND: Dose intensification of chemotherapy is associated with increased response rates in advanced breast cancer. Achievement of dose incrementation is usually limited by drug-dependent bone marrow toxicity. The recent availability of recombinant human colony-stimulating factors (CSFs) have made it possible to evaluate their potential in ameliorating chemotherapy-induced myelosuppression. The aim of this study was to evaluate tolerability and effectiveness of an intensified mitoxantrone, methotrexate and mitomycin-C (3M) regimen, given with G-CSF support in patients with advanced breast cancer (ABC). STUDY DESIGN: Twenty-eight eligible patients with advanced breast cancer were treated with mitomycin -C (7 mg/sqm i.v. every 4 weeks), methotrexate (35 mg/sqm i.v.) and mitoxantrone (7 mg/sqm i.v. every 2 weeks) for 6 cycles. Recombinant human granulocyte colony-stimulating factor (r-HuG-CSF, Filgrastim) (5 micrograms/kg/day) was given subcutaneously from day 2 to day 12 after each chemotherapy administration to prevent leukopenia. RESULTS: Of the 27 evaluable patients, 4 had complete response and 14 achieved partial response; the overall response rate was 63% (95% CI; 46.8%-82.2%). The median duration of response was 8 months (range, 4-13+). Chemotherapy-related toxicity was mild: only 3 out of 163 courses had to be postponed due to myelotoxicity. CONCLUSIONS: The 3M regimen given at 2- week intervals is a feasible, active and well toleratel treatment in patients not previously treated for metastatic breast cancer.

Adult↗