miRNome and Proteome Profiling of Small Extracellular Vesicles Secreted by Human Glioblastoma Cell Lines and Primary Cancer Stem Cells.

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults. Despite available therapeutic interventions, it is very difficult to treat, and a cure is not yet available. The intra-tumoral GBM heterogeneity is a crucial factor contributing to poor clinical outcomes. GBM derives from a small heterogeneous population of cancer stem cells (CSCs). In cancer tissue, CSCs are concentrated within the so-called niches, where they progress from a slowly proliferating phase. CSCs, as most tumor cells, release extracellular vesicles (EVs) into the surrounding microenvironment. To explore the role of EVs in CSCs and GBM tumor cells, we investigated the miRNA and protein content of the small EVs (sEVs) secreted by two GBM-established cell lines and by GBM primary CSCs using omics analysis. Our data indicate that GBM-sEVs are selectively enriched for miRNAs that are known to display tumor suppressor activity, while their protein cargo is enriched for oncoproteins and tumor-associated proteins. Conversely, among the most up-regulated miRNAs in CSC-sEVs, we also found pro-tumor miRNAs and proteins related to stemness, cell proliferation, and apoptosis. Collectively, our findings support the hypothesis that sEVs selectively incorporate different miRNAs and proteins belonging both to fundamental processes (e.g., cell proliferation, cell death, stemness) as well as to more specialized ones (e.g., EMT, membrane docking, cell junction organization, ncRNA processing).

Role of Lamin A/C as Candidate Biomarker of Aggressiveness and Tumorigenicity in Glioblastoma Multiforme.

Nuclear lamina components have long been regarded as scaffolding proteins, forming a dense fibrillar structure necessary for the maintenance of the nucleus shape in all the animal kingdom. More recently, mutations, aberrant localisation and deregulation of these proteins have been linked to several diseases, including cancer. Using publicly available data we found that the increased expression levels of the nuclear protein Lamin A/C correlate with a reduced overall survival in The Cancer Genome Atlas Research Network (TCGA) patients affected by glioblastoma multiforme (GBM). We show that the expression of the LMNA gene is linked to the enrichment of cancer-related pathways, particularly pathways related to cell adhesion and cell migration. Mimicking the modulation of LMNA in a GBM preclinical cancer model, we confirmed both in vitro and in vivo that the increased expression of LMNA is associated with an increased aggressiveness and tumorigenicity. In addition, delving into the possible mechanism behind LMNA-induced GBM aggressiveness and tumorigenicity, we found that the mTORC2 component, Rictor, plays a central role in mediating these effects.

Does screening for adverse effects improve health outcomes in epilepsy? A randomized trial.

OBJECTIVE: To determine whether systematic screening for adverse effects of antiepileptic drugs (AEDs) reduces toxicity burden and improves health-related quality of life in patients with epilepsy. METHODS: Consecutive patients with uncontrolled seizures aged ≥16 years and a high Adverse Event Profile (AEP) score were randomized to 2 groups and followed up for 18 months at 11 referral centers. AEP scores were made available to treating physicians at all visits in the intervention group, but not in the control group. Co-primary endpoints were changes in AEP scores and Quality of Life Inventory for Epilepsy-31 (QOLIE-31) scores. RESULTS: Of 809 enrolled patients able to complete the AEP questionnaire, 222 had AEP scores ≥45 and were randomized to the intervention (n = 111) or control group (n = 111). A total of 206 patients completed the 18-month follow-up. Compared with baseline, AEP scores decreased on average by 7.2% at 6 months, 12.1% at 12 months, and 13.8% at 18 months in the intervention group (p < 0.0001), and by 7.7% at 6 months, 9.2% at 12 months, and 12.0% at 18 months in controls (p < 0.0001). QOLIE-31 scores also improved from baseline to final visit, with a mean 20.7% increase in the intervention group and a mean 24.9% increase in the control group (p < 0.0001). However, there were no statistically significant differences in outcomes between groups for the 2 co-primary variables. CONCLUSIONS: Contrary to findings from a previous study, systematic screening for adverse effects of AEDs using AEP scores did not lead to a reduced burden of toxicity over usual physician treatment. ITALIAN MEDICINES AGENCY AIFA IDENTIFIER: FARM52K2WM_003. CLINICALTRIALSGOV IDENTIFIER: NCT03939507 (registered retrospectively in 2019; the study was conducted during the 2006-2009 period and registration of clinical trials was not a widely established practice when this study was initiated). CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that the additional collection of formal questionnaires regarding adverse effects of AEDs does not reduce toxicity burden over usual physician treatment.

Relationship between saliva and plasma rufinamide concentrations in patients with epilepsy.

The assay of saliva samples provides a valuable alternative to the use of blood samples for therapeutic drug monitoring (TDM), at least for certain categories of patients. To determine the feasibility of using saliva sampling for the TDM of rufinamide, we compared rufinamide concentrations in paired samples of saliva and plasma collected from 26 patients with epilepsy at steady state. Within-patient relationships between plasma rufinamide concentrations and dose, and the influence of comedication were also investigated. Assay results in the two tested fluids showed a good correlation (r2  = .78, P < .0001), but concentrations in saliva were moderately lower than those in plasma (mean saliva to plasma ratio = 0.7 ± 0.2). In eight patients evaluated at three different dose levels, plasma rufinamide concentrations increased linearly with increasing dose. Patients receiving valproic acid comedication had higher dose-normalized plasma rufinamide levels than patients comedicated with drugs devoid of strong enzyme-inducing or enzyme-inhibiting activity. Overall, these findings indicate that use of saliva represents a feasible option for the application of TDM in patients treated with rufinamide. Because rufinamide concentrations are lower in saliva than in plasma, a correction factor is needed if measurements made in saliva are used as a surrogate for plasma concentrations.

Melatonin Analogue Antiproliferative and Cytotoxic Effects on Human Prostate Cancer Cells.

Melatonin has been indicated as a possible oncostatic agent in different types of cancer, its antiproliferative role being demonstrated in several in vitro and in vivo experimental models of tumors. Specifically, melatonin was proven to inhibit cell growth of both androgen-dependent and independent prostate cancer cells, through various mechanisms. A number of melatonin derivatives have been developed and tested for their role in the prevention and treatment of neoplastic diseases. We recently proved the in vitro and in vivo anticancer activity of UCM 1037, a newly-synthetized melatonin analogue, on melanoma and breast cancer cells. In this study we evaluated UCM 1037 effects on cell proliferation, cell cycle distribution, and cytotoxicity in LNCaP, PC3, DU145, and 22Rv1 prostate cancer cells. We demonstrated significant dose- and time-dependent UCM 1037 antiproliferative effects in androgen-sensitive LNCaP and 22Rv1 cells. Data from flow cytometric studies suggest that UCM 1037 is highly cytotoxic in androgen-sensitive prostate cancer cells, although no substantial increase in the apoptotic cell fraction has been observed. UCM 1037 cytotoxic effects were much less evident in androgen-insensitive PC3 and DU145 cells. Experiments performed to gain insights into the possible mechanism of action of the melatonin derivative revealed that UCM 1037 down-regulates androgen receptor levels and Akt activation in LNCaP and 22Rv1 cells.

A simple and rapid HPLC-UV method for the determination of retigabine in human plasma.

A simple and rapid high-performance liquid chromatographic method with ultraviolet detection was developed for the quantitative determination of retigabine, known also as ezogabine, in human plasma. The assay uses a simple solid-phase extraction for sample preparation and direct injection of the extract into the chromatograph. Flupirtine is used as an internal standard. Chromatographic separation is achieved on a C18 Chromolith column (Chromolith Performance, 100 × 4.6 mm i.d.), using as mobile phase water/acetonitrile/methanol (72:18:10 v/v/v) mixed with 0.1% of 85% phosphoric acid. Isocratic elution is conducted at a flow rate of 1.5 mL min-1 . The total duration of a chromatographic run is 7 min. Calibration curves are linear over the 25-2000 ng mL-1 concentration range, with a limit of quantitation of 25 ng mL-1 . Other performance characteristics include high precision (intra- and inter-day coefficients of variation ≤12.6%) and high accuracy (99.7%-108.7%). The method is suitable for the investigation of concentration-response relationships in patients receiving therapeutic doses of retigabine.

Antiproliferative and pro-apoptotic activity of melatonin analogues on melanoma and breast cancer cells.

Melatonin plays different physiological functions ranging from the regulation of circadian rhythms to tumor inhibition, owing to its antioxidant, immunomodulatory and anti-aging properties. Due to its pleiotropic functions, melatonin has been shown to elicit cytoprotective processes in normal cells and trigger pro-apoptotic signals in cancer cells. The therapeutic potential of melatonin analogues prompted us to investigate the in vitro and in vivo antitumor activity of new melatonin derivatives and explore the underlying molecular mechanisms. The experiments revealed that the new melatonin analogues inhibited the growth of melanoma and breast cancer cells in a dose- and time-dependent manner. In addition, our results indicated that melatonin derivative UCM 1037 could induce apoptosis in melanoma and breast cancer cells, as well as cell necrosis, in MCF-7. Together, apoptosis and necrosis could be two possible mechanisms to explain the cytotoxic effect of the melatonin analogue against cancer cells. The suppression of tumor growth by the melatonin analogues was further demonstrated in vivo in a xenograft mice model. A decrease in the activation of MAPK pathway was observed in all cancer cells following UCM 1037 treatment. Overall, this study describes a promising antitumor compound showing antiproliferative and cytotoxic activity in melanoma and breast cancer cells.

A prospective study of direct medical costs in a large cohort of consecutively enrolled patients with refractory epilepsy in Italy.

OBJECTIVE: To evaluate direct medical costs and their predictors in patients with refractory epilepsy enrolled into the SOPHIE study (Study of Outcomes of PHarmacoresistance In Epilepsy) in Italy. METHODS: Adults and children with refractory epilepsy were enrolled consecutively at 11 tertiary referral centers and followed for 18 months. At entry, all subjects underwent a structured interview and a medical examination, and were asked to keep records of diagnostic examinations, laboratory tests, specialist consultations, treatments, hospital admissions, and day-hospital days during follow-up. Study visits included assessments every 6 months of seizure frequency, health-related quality of life (Quality of Life in Epilepsy Inventory 31), medication-related adverse events (Adverse Event Profile) and mood state (Beck Depression Inventory-II). Cost items were priced by applying Italian tariffs. Cost estimates were adjusted to 2013 values. RESULTS: Of 1,124 enrolled individuals, 1,040 completed follow-up. Average annual cost per patient was € 4,677. The highest cost was for antiepileptic drug (AED) treatment (50%), followed by hospital admissions (29% of overall costs). AED polytherapy, seizure frequency during follow-up, grade III pharmacoresistance, medical and psychiatric comorbidities, and occurrence of status epilepticus during follow-up were identified as significant predictors of higher costs. Age between 6 and 11 years, and genetic (idiopathic) generalized epilepsies were associated with the lowest costs. Costs showed prominent variation across centers, largely due to differences in the clinical characteristics of cohorts enrolled at each center and the prescribing of second-generation AEDs. Individual outliers associated with high costs related to hospital admissions had a major influence on costs in many centers. SIGNIFICANCE: Refractory epilepsy is associated with high costs that affect individuals and society. Costs differ across centers in relation to the characteristics of patients and the extent of use of more expensive, second-generation AEDs. Epilepsy-specific costs cannot be easily differentiated from costs related to comorbidities.

Down-modulation of Bcl-2 sensitizes PTEN-mutated prostate cancer cells to starvation and taxanes.

BACKGROUND: The critical role of PTEN in regulating the PI3K/Akt/mTOR signaling pathway raises the possibility that targeting downstream effectors of the PI3K pathway, such as Bcl-2, might be an effective anti-proliferative strategy for PTEN-deficient prostate cancer cells. METHODS: Four prostate cancer cell lines (LNCaP, PC3, DU145, 22Rv1) were assayed for their levels of total Akt and Ser473 phosphorylated Akt (p-Akt) by Western Blotting; their growth rates and sensitivity to different doses of paclitaxel were determined by cell counts after Trypan Blue dye exclusion assay. Cells were subjected to different combinations of starvation (growth factors and/or aminoacids withdrawal), paclitaxel treatment and Bcl-2 silencing by siRNA. Cell viability was evaluated by Trypan Blue dye exclusion assay, Propidium Iodide (PI) and Annexin-V/PI staining. RESULTS: We assessed the sensitivity of different prostate cancer cell lines to starvation and we observed a differential response correlated to the levels of Akt activation. The four prostate cancer cell lines also showed different sensitivity to taxol treatments; LNCaP and 22Rv1 cells were more resistant to paclitaxel than DU145 and PC3 cells. Combining taxol with growth factors and aminoacids deprivation leaded to a more than additive reduction of cell viability compared to single treatments in PTEN-mutant LNCaP cells. Down-modulation of anti-apoptotic Bcl-2 protein by siRNA sensitized LNCaP cells to taxanes and starvation induced cell death. CONCLUSIONS: Silencing Bcl-2 in PTEN-mutated prostate cancer cells enhances the apoptotic effects of combined starvation and taxol treatments, indicating that inhibition of Bcl-2 may be of significant value in PTEN-mutant tumor therapy.

Off-label prescribing of antiepileptic drugs in pharmacoresistant epilepsy: a cross-sectional drug utilization study of tertiary care centers in Italy.

PURPOSE: To assess the extent of off-label prescribing of antiepileptic drugs (AEDs) and associated variables in a large population of patients with pharmacoresistant epilepsy. METHODS: Descriptive analysis of data recorded from consecutively enrolled patients with pharmacoresistant epilepsy attending 11 tertiary referral centers in Italy. Off-label use was stratified by therapeutic indication, dose, and age. Multivariate logistic regression was used to identify variables associated with off-label prescription. RESULTS: Of a total of 1,124 patients enrolled between November 2006 and August 2007, 53 % (101/191) of children and 31 % (287/933) of adults were receiving at least one off-label AED prescription. Among adults, off-label use was related primarily to indication and was highest for clobazam (100 %) and ethosuximide (40 %), followed by lamotrigine (25 %), and vigabatrin (25 %). In children, clobazam (100 %), lamotrigine (79 %), vigabatrin (55 %), ethosuximide (46 %), and levetiracetam (43 %) were most frequently used off-label, with indication or age being the main causes depending on the specific AED. Logistic regression analysis indicated that higher rates of off-label use were associated with a polytherapy regimen (odds ratio [OR] 2.50, 95 % confidence interval [95 % CI], 1.55-4.03), pediatric age (2.49, 1.66-3.76), having failed ≥3 AEDs (2.16, 1.04-4.48), a diagnosis of generalized epilepsy with structural/metabolic or unknown etiology (2.97, 1.25-7.04), and increasing seizure frequency (1.07, 1.01-1.14). CONCLUSIONS: Off-label prescribing of AEDs is common among patients with pharmacoresistant epilepsy and is influenced by demographic and disease-related characteristics. Studies are needed to improve the quality of evidence guiding epilepsy treatment, and to evaluate the risks and benefits of off-label prescribing in epilepsy.

Determinants of health-related quality of life in pharmacoresistant epilepsy: results from a large multicenter study of consecutively enrolled patients using validated quantitative assessments.

PURPOSE: To evaluate the relative contribution of demographic and epilepsy-related variables, depressive symptoms, and adverse effects (AEs) of antiepileptic drugs (AEDs) to health-related quality of life (HRQOL) in adults with pharmacoresistant epilepsy. METHODS: Individuals with epilepsy whose seizures failed to respond to at least one AED were enrolled consecutively at 11 tertiary referral centers. HRQOL was assessed by the Quality of Life in Epilepsy Inventory-31 (QOLIE-31), AEs by the Adverse Event Profile (AEP), and depressive symptoms by the Beck Depression Inventory-II (BDI-II). Multivariate linear regression models were used to identify variables associated with QOLIE-31 total score and subscale scores. KEY FINDINGS: Of 933 enrolled individuals aged 16 years or older, 809 (87%) were able to complete the self-assessment instruments and were included in the analysis. Overall, 61% of the variance in QOLIE-31 scores was explained by the final model. The strongest predictors of HRQOL were AEP total scores (ß = -0.451, p < 0.001) and BDI-II scores (ß = -0.398, p < 0.001). These factors were also the strongest predictors of scores in each of the seven QOLIE-31 subscales. Other predictors of HRQOL were age (ß = -0.060, p = 0.008), lack of a driving license (ß = -0.053, p = 0.018), pharmacoresistance grade, with higher HRQOL in individuals who had failed only one AED (ß = 0.066, p = 0.004), and location of the enrolling center. Epilepsy-related variables (seizure frequency, occurrence of tonic-clonic seizures, age of epilepsy onset, disease duration) and number of AEDs had no significant predictive value on HRQOL. The AEP total score was the strongest negative predictor of HRQOL in the subgroup of 362 patients without depressive symptoms (BDI-II score <10), but even in this subgroup the BDI-II score was retained as a significant predictor. SIGNIFICANCE: In individuals with pharmacoresistant epilepsy, AEs of medication and depressive symptoms are far more important determinants of HRQOL than seizures themselves. When seizure freedom cannot be achieved, addressing depressive comorbidity and reducing the burden of AED toxicity is likely to be far more beneficial than interventions aimed at reducing the frequency of seizures.

Development and validation of an HPLC-UV detection assay for the determination of rufinamide in human plasma and saliva.

The development of a simple and rapid high-performance liquid chromatography (HPLC) method for the determination of the new antiepileptic drug rufinamide (RFN) in human plasma and saliva is reported. Samples (250 µl) are alkalinized with ammonium hydroxide (pH 9.25) and extracted with dichloromethane using metoclopramide as internal standard. Separation is achieved with a Spherisorb silica column (250 × 4.6 mm i.d., 5 µm) at 30 °C using as mobile phase a solution of methanol/dichloromethane/n-hexane 10/25/65 (vol/vol/vol) mixed with 6 ml ammonium hydroxide. The instrument used was a Shimadzu LC-10Av chromatograph and flow rate was 1.5 ml min(-1), with a LaChrom L-7400 UV detector set at 230 nm. Calibration curves are linear [r(2) = 0.998 ± 0.002 for plasma (n = 10) and r(2) = 0.999 ± 0.001 for saliva (n = 9)] over the range of 0.25-20.0 µg ml(-1), with a limit of quantification at 0.25 µg ml(-1). Precision and accuracy are within current acceptability standards. The assay is suitable for pharmacokinetic studies in humans and for therapeutic drug monitoring.

Relationship between adverse effects of antiepileptic drugs, number of coprescribed drugs, and drug load in a large cohort of consecutive patients with drug-refractory epilepsy.

PURPOSE: To evaluate the adverse effects (AEs) of antiepileptic drugs (AEDs) in adults with refractory epilepsy and their relationship with number of coprescribed AEDs and AED load. METHODS: Patients with refractory epilepsy were enrolled consecutively at 11 tertiary referral centers. AEs were assessed through unstructured interview and the Adverse Event Profile (AEP) questionnaire. AED loads were calculated as the sum of prescribed daily dose (PDD)/defined daily dose (DDD) ratios for each coprescribed AED. RESULTS: Of 809 patients enrolled, 709 had localization-related epilepsy and 627 were on polytherapy. AED loads increased with increasing number of AEDs in the treatment regimen, from 1.2 +/- 0.5 for patients on monotherapy to 2.5 +/- 1, 3.7 +/- 1.1, and 4.7 +/- 1.1 for those on two, three, and > or =4 AEDs, respectively. The number of spontaneously reported AEs correlated with the number of AEs identified by the AEP (r = 0.27, p < 0.0001). AEP scores did not differ between patients with monotherapy and patients with polytherapy (42.8 +/- 11.7 vs. 42.6 +/- 11.2), and there was no correlation between AEP scores and AED load (r = -0.05, p = 0.16). CONCLUSIONS: AEs did not differ between monotherapy and polytherapy patients, and did not correlate with AED load, possibly as a result of physicians' intervention in individualizing treatment regimens. Taking into account the limitations of a cross-sectional survey, these findings are consistent with the hypothesis that AEs are determined more by individual susceptibility, type of AEDs used, and physicians' skills, than number of coprescribed AEDs and AED load.

MYC prevents apoptosis and enhances endoreduplication induced by paclitaxel.

BACKGROUND: The role of the MYC oncogene in the apoptotic pathways is not fully understood. MYC has been reported to protect cells from apoptosis activation but also to sensitize cells to apoptotic stimuli. We have previously demonstrated that the down-regulation of Myc protein activates apoptosis in melanoma cells and increases the susceptibility of cells to various antitumoral treatments. Beyond the well-known role in the G1-->S transition, MYC is also involved in the G2-M cell cycle phases regulation. METHODOLOGY/PRINCIPAL FINDINGS: In this study we have investigated how MYC could influence cell survival signalling during G2 and M phases. We used the microtubules damaging agent paclitaxel (PTX), to arrest the cells in the M phase, in a p53 mutated melanoma cell line with modulated Myc level and activity. An overexpression of Myc protein is able to increase endoreduplication favoring the survival of cells exposed to antimitotic poisoning. The PTX-induced endoreduplication is associated in Myc overexpressing cells with a reduced expression of MAD2, essential component of the molecular core of the spindle assembly checkpoint (SAC), indicating an impairment of this checkpoint. In addition, for the first time we have localized Myc protein at the spindle poles (centrosomes) during pro-metaphase in different cell lines. CONCLUSIONS: The presence of Myc at the poles during the prometaphase could be necessary for the Myc-mediated attenuation of the SAC and the subsequent induction of endoreduplication. In addition, our data strongly suggest that the use of taxane in antitumor therapeutic strategies should be rationally based on the molecular profile of the individual tumor by specifically analyzing Myc expression levels.

Changes in lamotrigine pharmacokinetics during pregnancy and the puerperium.

To assess changes in the pharmacokinetics of the anti-epileptic drug lamotrigine (LTG) during pregnancy, plasma LTG concentrations at steady-state were determined at different intervals during 11 pregnancies in 10 women with epilepsy stabilized on long-term LTG therapy. In the five pregnancies that could be assessed both during gestation and after delivery, plasma LTG concentrations increased on average by 164% (range +75 to +351%) between the last observation during pregnancy and the puerperium (P < 0.05). When all pregnancies monitored during pregnancy were considered, plasma LTG concentrations declined by an average of 20% (range -64% to +13%) between the first and the last assessment before delivery. These findings confirm that plasma LTG concentrations decrease markedly during pregnancy and that, at least in some cases, this effect occurs as early as the first trimester. Because there is a large interindividual variability in the magnitude and time course of the pregnancy-associated pharmacokinetic changes, it is desirable to establish baseline plasma LTG concentrations in all women of childbearing potential and to monitor LTG levels at frequent intervals during pregnancy and the puerperium.

Synergic antiproliferative and antiangiogenic effects of EGFR and mTor inhibitors on pancreatic cancer cells.

The in vitro efficacy of both EGFR inhibitor gefitinib and mTor inhibitor rapamycin, either administrated alone or in different combination schedules, was analysed in four pancreas cancer cell lines. Both drugs were found to induce cell growth inhibition, apoptosis as well as a slight but stable accumulation of cells in the G0/G1 phase. In all cell lines, neither gefitinib nor rapamycin affected EGFR and the expression of its downstream effectors. By contrast, gefitinib inhibited in a fast and completely way p-EGFR and partially p-Akt while a 3 days-rapamycin exposure resulted in the inhibition of the expression of both mTor and p70S6K. Moreover, after early stimulation, the mTor inhibitor produced a progressive, and almost complete inhibition of p-Akt. The analysis of combined gefitinib and rapamycin administration showed a clear schedule-dependent activity which turned out to be synergic only when gefitinib was given before rapamycin. This synergism seemed to depend on increase of both p-Akt and p70S6K inhibition, the greater the induction of apoptosis, the higher the decrease in cell cycle rate. Moreover, the antiangiogenic activity of the two drugs given in combination was demonstrated by a strong reduction of VEGF release which turned out to be more pronounced in the synergic schedule, and HIF-1alpha inhibition-independent. Our results suggest that the schedule of gefitinib followed by rapamycin, acting at different levels of the EGFR cellular pathway, could induce antitumor and antiangiogenic effects of clinical interest in the pancreas cancer model.

A novel enantioselective microassay for the high-performance liquid chromatography determination of oxcarbazepine and its active metabolite monohydroxycarbazepine in human plasma.

A simple and innovative assay is described that allows the determination of the antiepileptic drug oxcarbazepine and the chiral separation of the two enantiomers of its active metabolite monohydroxycarbazepine (licarbazepine). The assay requires liquid-liquid extraction of the sample (200 microL) into tert-butyl methyl ether and dichloromethane, drying of the organic phase under a nitrogen stream, reconstitution with the mobile phase, and injection in the high-performance liquid chromatography system after filtering. Separation of oxcarbazepine, R-(-)-monohydroxycarbazepine, S-(+)-monohydroxycarbazepine, and the second-step metabolite 10,11-trans-dihydroxycarbamazepine (racemate) is achieved with a Chiralcel ODR column and potassium hexafluorophosphate/acetonitrile as mobile phase. Detection is by ultraviolet absorbance at 210 nm. Standard curves are linear (r2 > or = 0.999) over the range of 0.1 to 25 microg/mL for each analyte with a limit of quantification of 0.1 microg/mL (1 ng injected) for all compounds. Within-day and between-day precision is better than 12% and within-day and between-day accuracy is between 99% and 116% for each compound. These performance characteristics are adequate for pharmacokinetic studies and for therapeutic drug monitoring. However, because the two enantiomers of monohydroxycarbazepine exhibit similar pharmacologic activity, nonenantioselective assays are likely to be more cost-effective for therapeutic drug monitoring purposes.

Stereoselective determination of vigabatrin enantiomers in human plasma by high performance liquid chromatography using UV detection.

A rapid and simple high-performance liquid chromatographic method for the determination of the R-(-)- and S-(+)-enantiomers of the antiepileptic drug vigabatrin in human plasma is described. After adding the internal standard (1-aminomethyl-cycloheptyl-acetic acid), plasma samples (200 microL) are deproteinized with acetonitrile and the supernatant is derivatized with 2,4,6 trinitrobenzene sulfonic acid (TNBSA). Separation is achieved on a reversed-phase cellulose-based chiral column (Chiralcel-ODR, 250 mm x 4.6 mm i.d.) using 0.05 M potassium hexafluorophosphate (pH 4.5)/acetonitrile/ethanol (50:40:10 vol/vol/vol) as mobile phase at a flow-rate of 0.9 mL/min. Chromatographic selectivity is improved by concentrating the derivatives on High Performance Extraction Disk Cartridges prior to injection. Detection is at 340 nm. Calibration curves are linear (r(2)> or =0.999) over the range of 0.5-40 microg/mL for each enantiomer, with a limit of quantification of 0.5 microg/mL for both analytes. The assay is suitable for therapeutic drug monitoring and for single-dose pharmacokinetic studies in man.

Oligopeptides impairing the Myc-Max heterodimerization inhibit lung cancer cell proliferation by reducing Myc transcriptional activity.

Deregulated CMYC gene causes cell transformation and is often correlated with tumor progression and a worse clinical outcome of cancer patients. The transcription factor Myc functions by heterodimerizing with its partner, Max. As a strategy to inhibit Myc activity, we have synthesized three small peptides corresponding to segments of the leucine zipper (LZ) region of Max. The purpose of these peptides is to occupy the site of recognition between Myc and Max located in the LZ and inhibit-specific heterodimerization between these proteins. We have used the synthesized oligopeptides in two lung cancer cell lines with different levels of Myc expression. Results demonstrate that: (i) the three peptides resulted equally effective in competing the interaction between Myc and Max in vitro; (ii) they were efficiently internalized into the cells and significantly inhibited cell growth in the cells showing the highest Myc expression; (iii) one specific peptide, only nine aminoacids long, efficiently impaired the transcriptional activity of Myc in vivo, showing a more stable interaction with this protein. Our results are relevant to the development of novel anti-tumoral therapeutic strategies, directed to Myc-overexpressing tumors.

Changes in the disposition of oxcarbazepine and its metabolites during pregnancy and the puerperium.

PURPOSE: To determine potential changes in the plasma concentrations of oxcarbazepine (OXC) and its metabolites during pregnancy and puerperium. METHODS: Five women receiving OXC monotherapy were followed prospectively during pregnancy and the puerperium. Four women were enrolled in the first trimester, and one woman, 2 weeks before delivery. Steady-state concentrations of OXC, its active R-(-)- and S-(+)-monohydroxy derivatives (MHD), and the additional metabolite carbamazepine-10,11-trans-dihydrodiol (DHD) were measured at regular intervals by an enantioselective HPLC assay. RESULTS. In all samples, S-(+)-MHD was the most abundant compound in plasma and accounted almost entirely for the amount of active moiety (defined as the molar sum of OXC, R-(-)-MHD, and S-(+)-MHD) found in the circulation. The dose-normalized concentrations of active moiety decreased markedly during gestation and, in four of the five patients, increased strikingly after delivery. Plasma concentrations of S-(+)-MHD mirrored closely the levels of the active moiety. Plasma concentrations of the parent drug and other metabolites also tended to decrease during pregnancy and to increase after delivery. CONCLUSIONS: During treatment with OXC, S-(+)-MHD is by far the most abundant active compound in plasma. The concentration of this metabolite as well as the active moiety may decrease markedly during pregnancy and may increase severalfold after delivery. Because of these striking pharmacokinetic changes, the clinical response should be monitored closely in OXC-treated women throughout pregnancy and the puerperium.