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Biomedical subjects

P Conte

Publications and source records attributed to P Conte.

65 records · Page 4Linked to original sources

Elemental quantitation of natural organic matter by CPMAS 13C NMR spectroscopy.

Cross-polarized magic-angle-spinning NMR (CPMAS-NMR) techniques are assumed to be only semi-quantitative in the assessment of carbon distribution in humic substances or natural organic matter, due to a number of interferences such as spinning side bands (SSB) in spectra, paramagnetic species in samples, and low or remote protonation of aromatic carbons. Fast rotor spin rates or direct polarization NMR techniques are normally applied to improve quantitative signal detectability. Variable contact time pulse sequences were used here to obtain CPMAS-NMR spectra of organic compounds of known structure and different humic substances. Integration of spectral areas, previously subtracted of SSB, and relative stoichiometric factors were used for mathematical elaboration to calculate the elemental content in samples. These values did not significantly differ from those obtained by direct determination of elemental content with quantitative elemental analysis. Our results showed that the carbon observed CPMAS-NMR provides a quantitative representation of the whole carbon content in humic substances.

Magnetic Resonance Spectroscopy↗

Combined effects of an oxidative enzyme and dissolved humic substances on 13C-labelled 2,4-D herbicide as revealed by high-resolution 13C NMR spectroscopy.

Phenoxyalkanoic acids are a widely used class of herbicides. This work employed high-resolution 13C NMR to study the structural changes induced by humic substances and horseradish perodixase on 2,4-dichlorophenoxyacetic acid (2,4-D) 13C-labelled in the side chain. NMR spectra showed that humic substances chemically catalyze abiotic splitting of [13C]2,4-D into 2,4-dichlorophenol and [13C]acetic acid at pH 7 but not at pH 4.7. Peroxidase did not catalyze the oxidative degradation of [13C]2,4-D at any pH tested and inhibited the effect of humic substances. Catalytic degradation by humic substances was attributed to free-radical reactions enhanced by the stereochemical contribution of large conformational structures formed by heterogeneous humic molecules at neutral pH. Inhibition of 2,4-D degradation when humic substances were combined with peroxidase was explained by modification of both chemical and conformational humic structure due to peroxidase-promoted oxidative cross-coupling among humic molecules. Our findings show for the first time that the abiotic degradation of 2,4-D is catalyzed by dissolved humic substances at neutral pH.

2,4-Dichlorophenoxyacetic Acid↗

Treatment options in patients with recurrent ovarian cancer.

The majority of patients with advanced ovarian cancer need a second-line treatment for recurrent disease after surgical cytoreduction and first-line chemotherapy. In these patients, treatment planning is mainly dependent on the platinum-free-interval. The patients may be distinguished as platinum-refractory (progression under platinum-based therapy), platinum-resistant (relapse within 6 months), or platinum-sensitive (relapse after 6 months). Patients with platinum-refractory or -resistant disease should be encouraged to enter clinical trials. Alternatively, these patients could receive tamoxifen or a non-platinum single-agent therapy. Since response rate and duration to different single-agents are similar, patient convenience, toxicities from prior treatment, side-effects and costs play a role in the drug selection for salvage chemotherapy. Patients with platinum-sensitive disease should receive carboplatin based or carboplatin-plus paclitaxel-based regimens. Secondary surgical cytoreduction may have a role in highly selected patients with good performance status, with long disease-free interval and without extra-abdominal or liver metastases.

Female↗

Augmentation of antineoplastic effects by the combination of recombinant human tumor necrosis factor and mitoxantrone on primary culture of human ovarian cancer cells.

Recombinant human tumor Necrosis Factor (rHuTNF) produced dose-dependent cytotoxicity against human ovarian cancer cells, OSC and OMC, obtained from fresh ascites. A combination of rHuTNF and the topoisomerase II inhibitor, Mitoxantrone, produced dose-dependent synergistic cytotoxicity on OSC and OMC cells. When OMC cells were incubated simultaneously for one hour with rHuTNF and Mitoxantrone, increased numbers of DNA single-strands breaks were produced. rHuTNF alone did not induce DNA single-strands breaks. These data are consistent with a role for topoisomerase-linked DNA lesions in the rHuTNF mediated potentiation of killing cells by Mitoxantrone.

Cell Survival↗

Prognostic factors in node positive primary breast cancer patients treated with adjuvant CMF.

The influence of various patient and disease-related parameters on survival (S) and disease-free survival (DFS) in 217 node positive primary breast cancer patients treated with surgery followed by adjuvant i.v. cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) was evaluated by univariate and multivariate analyses. Five year actuarial S and DFS were 73.3% and 54.8%, respectively. Univariate analysis revealed that patient age, number of involved axillary nodes and ER status had a significant impact on both S and DFS. PgR positive tumors had improved DFS but no S difference was observed. Menopausal status predicted S but not DFS. Primary tumor size and CMF-induced amenorrhea did not predict disease outcome. Multivariate analysis demonstrated that only degree of nodal involvement and PgR status had independent significant impact on prognosis. Both S and DFS are significantly influenced by the number of involved nodes, whereas improved DFS but not S was evident in patients with PgR positive tumors.

Adult↗

[Electrophysiologic follow-up (brainstem acoustic evoked potentials and visual evoked potentials) in chronic uremic patients treated with various therapeutic protocols].

The aim of our study was to evaluate the possibility of recording also sub-clinical alterations of the Central Nervous System during chronic uremia by means of the study of Pattern-Reversal Visual Evoked Potentials (P-R V.E.Ps) and Brainstem Acoustic Evoked Potentials (B.A.E.Ps), to study their behaviour in answer to different kinds of treatment and follow their possible modifications during the time. With this purpose the uremic patients were divided into therapeutic groups: only dietetic and pharmacological treatment, conventional hemodialysis, hemodiafiltration, peritoneal dialysis and well functioning kidney transplant. A first record of Evoked Potentials was made in 1985 and the values were compared with those obtained by an homogeneous control group. The same patients were evaluated 3 years later and the two records results were compared. In both cases the most important percentage of altered values were found in the group under only dietetic and pharmacological treatment, the less important in the transplanted patients and these data were stable at the follow-up. So that Evoked Potentials are a good test in chronic uremia and the best therapy able to hinder the alterations of Central Nervous System arising during chronic renal failure would seen to be kidney transplant.

Adult↗

Sensitization of human glioblastoma T98G cells to VP16 and VM26 by human tumor necrosis factor.

The effect of Tumor Necrosis Factor (TNF) on VP16 or VM26 cytotoxicity was studied in a human glioblastoma cell line T98G, which expresses TNF-receptors. Although T98G cells did not produce TNF endogenously they were resistant to the cytolytic effect of TNF. T98G cells were also moderately sensitive to the action of VP16 or VM26. TNF given at 1000 U/ml was able to increase the cell drug-sensitivity significantly. This effect was due to an increase in the VP 16-induced cleavable-complexes by TNF. These findings suggest that TNF specifically sensitizes human glioma T98G cells to the effects of VP 16 of VM26.

DNA Damage↗

Platinum compounds and paclitaxel in advanced epithelial ovarian cancer.

Cisplatin is the most active agent currently employed in epithelial ovarian cancer. A meta-analysis of the Advanced Ovarian Cancer Trialists Group suggested that in terms of immediate survival platinum-based therapy was superior to nonplatinum regimens and that regimens including cisplatin were superior to single agent cisplatin given at the same doses. Intraperitoneal cisplatin seems to offer some clinical benefit when compared to systemic cisplatin in patients with minimal residual disease after initial surgery. An overview on the role of anthracyclines using data from the Advanced Ovarian Cancer Trialists Group and the Ovarian Cancer Meta-Analysis Project suggested that the addition of doxorubicin significantly improves survival and that the size of this benefit is of a similar magnitude to that of platinum. Carboplatin and cisplatin are equiactive, and the different spectrum of toxicities could offer an appropriate criterion for the choice of the platinum analogue to use in the individual patient. At present, there is no conclusive evidence that cisplatin dose intense regimens are beneficial, and the issue of dose intensity must still be considered experimental. The combination of cisplatin + paclitaxel is able to obtain a better progression-free survival and survival than the association cisplatin + cyclophosphamide. Phase I-II trials on regimens including platinum compounds, anthracyclines and paclitaxel are currently ongoing.

Antineoplastic Agents↗