Chemical modification of waxy maize starch by esterification with saturated fatty acid chlorides: Synthesis, physicochemical and emulsifying properties.

In the current study, the physicochemical and emulsifying properties of modified waxy maize starch obtained through a new environmentally friendly method of esterification were evaluated. The starch modification was carried out in NaOH solution with different levels of octanoyl, myristoyl, and stearoyl chlorides. Increasing the fatty acid chlorides concentration led to the degree of substitution increment, while reaction efficiency and yield decreased. Based on fourier transform infrared spectroscopy results, the presence of two new bands of carbonyl (1740-1750 cm-1) and carboxyl (1570 cm-1) groups in the ester bond confirmed the successful starch esterification process. The level of 0.1 mL fatty acid chlorides/g of starch demonstrated the highest emulsifying properties. Upon esterification, the crystalline structure of amylopectin was destroyed, indicating no gelatinization features. Therefore, using the fatty acid chlorides in an alkaline condition could be suggested as a feasible way to modify waxy maize starch toward hydrophobicity increment with desirable properties.

Chitosan/carboxymethylcellulose-stabilized poly(lactide-co-glycolide) particles as bio-based drug delivery carriers.

Poly(lactide-co-glycolide) (PLGA) colloidal particles stabilized by complexes of two oppositely charged polysaccharides, chitosan (cationic, CS) and sodium carboxymethylcellulose (anionic, NaCMC), were fabricated. Dichloromethane containing dissolved PLGA was first emulsified in an aqueous phase containing mixtures of CS and NaCMC. Evaporation of dichloromethane from the resulting emulsion led to CS/NaCMC-covered-PLGA particles. CS and NaCMC contents affected the short-term stability of PLGA particles and also their intrinsic characteristics. The particles displayed pH-dependent characteristic. Zeta potential varied from +54 to -50 mV when pH was varied from 3 to 10. CS/NaCMC-covered-PLGA particles showed colloidal stability, over a wider pH range as compared to CS-covered-PLGA particles. Curcumin, a model hydrophobic drug, was encapsulated into the particles up to 10 wt% of PLGA. The CS/NaCMC-covered-PLGA particles loaded with curcumin showed delayed release in mildly acidic conditions and faster release in neutral and basic conditions. Cytotoxicity experiments were carried out with human colorectal carcinoma cells.

Dextran-covered pH-sensitive oily core nanocapsules produced by interfacial Reversible Addition-Fragmentation chain transfer miniemulsion polymerization.

Aiming to prepare oily core pH-sensitive nanocapsules (NCs) for anticancer drugs delivery, the use of a dextran-based transurf (DexN3-τCTAγ) as both stabilizer and macromolecular chain transfer agent in methyl methacrylate/2-(diethylamino)ethyl methacrylate (MMA/DEAEMA) miniemulsion copolymerization was investigated. NCs of about 195 nm with an oily-core of Miglyol 810 (M810) and a dextran coverage covalently linked to the poly(MMA-co-DEAEMA) intern shell have been obtained. Compared to the non-sensitive PMMA-based NCs (prepared in a similar way), these novel objects were shown to swell in acidic media and to trigger Coumarin 1 release in physiological relevant pH range. As a starting point of NCs biological effects, cytotoxicity and NCs-proteins interactions studies were performed with both PMMA and poly(MMA-co-DEAEMA)-based NCs. Finally, free azide functions from dextran-based coverage were successfully exploited to attach fluorescent model dyes to NCs surface. The overall results suggest that this novel NCs platform could be potentially used as drug nanocarriers for intravenous injection.

Encapsulation of monomyristin into polymeric nanoparticles improved its in vitro antiproliferative activity against cervical cancer cells.

The cytotoxicity of monomyristin (MM), a monoacylglycerol, was investigated against cervical cancer cells (HeLa) and two normal cells (Vero and endometrial epithelial cells). MM exhibited cytotoxicity specifically to HeLa cells and not against normal cells except at the highest investigated doses (> 500 µg/mL). MM was showed to increase apoptotic dead cells by intrinsic mitochondrial pathway. To overcome the poor water solubility of MM and increase its efficacy against HeLa cells, MM was encapsulated into dextran-covered polylactide (PLA) nanoparticles (NPs). NPs comprised a PLA core which encapsulated MM and a superficial layer of dextran loops which was used for conjugating a protein, transferrin (Tf), known to be overexpressed on cancer cells' surface. Encapsulation of MM into NPs increased its cytotoxicity against HeLa cells at lower doses of MM than free MM. Additionally, the presence of conjugated Tf further increased the cytotoxicity of MM against HeLa cells as compared to non-conjugated NPs. Remarkably, both conjugated and non-conjugated MM loaded NPs were safe to normal cells (Vero and endometrial).

Dilational rheology of oil/water interfaces covered by amphiphilic polysaccharides derived from dextran.

This work studied the adsorption at dodecane/water interface of amphiphilic polysaccharides derived from dextran (a nonionic bacterial polysaccharide) by random attachment of phenoxy groups along the chains (between 10 and 20 attached phenoxy groups per 100 glucose repeat units). The long-time kinetics of interfacial tension decrease was satisfactorily described assuming diffusion-limited adsorption of hydrophobic units (over 4h). Dilational rheology of dodecane/water interface was studied for the first time with that kind of amphiphilic polysaccharides and evidenced a significant elastic component. For all dextran derivatives, experimental results were conveniently described using Lucassen-van den Tempel model which assumed diffusion-limited of surface active species. The characteristic frequency increased with the number of attached phenoxy groups and its order of magnitude (10-3-10-2rad.s-1) was consistent with estimations based on the previous model. Experimental results were compared to those obtained with commercial stabilizers like Pluronics (L64, P105, F68 and F127) and Tween 80.

Bioproduction and anticancer activity of biosurfactant produced by the dematiaceous fungus Exophiala dermatitidis SK80.

A new biosurfactant producer was isolated from palm-oilcontaminated soil and later identified through morphology and DNA sequencing as the yeast-like fungus Exophiala dermatitidis. Biosurfactant production was catalyzed by vegetable oil, supplemented with a basal medium. The culture conditions that provided the biosurfactant with the highest surface activity were found to be 5% palm oil with 0.08% NH4NO3, at a pH of 5.3, with shaking at 200 rpm, and a temperature of 30 degrees C for a 14-day period of incubation. The biosurfactant was purified, in accordance with surfactant properties, by solvent fractionation using silica gel column chromatography. The chemical structure of the strongest surface-active compound was elucidated through the use of NMR and mass spectroscopy, and noted to be monoolein, which then went on to demonstrate antiproliferative activity against cervical cancer (HeLa) and leukemia (U937) cell lines in a dose-dependent manner. Interestingly, no cytotoxicity was observed with normal cells even when high concentrations were used. Cell and DNA morphological changes, in both cancer cell lines, were observed to be cell shrinkage, membrane blebbling, and DNA fragmentation.

High-dose methotrexate in adults with osteosarcoma: a population pharmacokinetics study and validation of a new limited sampling strategy.

Preoperative high-dose methotrexate (HD-MTX) with folinic acid (leucovorin) rescue is still a mainstay in the treatment of osteosarcoma. This anticancer agent is characterized by a narrow therapeutic index and wide interpatients variability. To ensure effective and safe administration of HD-MTX, we had earlier developed an adaptive-dosing schedule with a feedback strategy. In our institute, the MTX dosage was tailored according to individual pharmacokinetics parameters, determined in real time both from two blood samples (3.5 and 4.5 h) and from Bayesian population parameters. Up to 20 g of MTX was safely administered as 8-h infusions. Low MTX elimination rate has, however, been reported in 15-20% of the patients, and forecasting the MTX elimination phase and the management of leucovorin rescue is still a challenging issue in clinical oncology. This study aims at identifying the clinical or biological covariates related to impaired MTX clearance, and at validating a new limited sampling strategy (LSS), allowing for the accurate prediction of the MTX terminal elimination phase. This retrospective study was carried out on 49 patients (30 men, 19 women; mean age, 26.7 years) treated for osteosarcoma with HD-MTX. The population and individual pharmacokinetics parameters were computed, before the identification of the relevant covariates. Different LSSs were then tested, to predict accurately when the MTX plasma concentrations would drop below 0.2 micromol/l, the threshold associated with the end of the rescue of leucovorin with alkaline hydration. Two main covariates (creatinemia clearance and alanine aminotransferase) were correlated with MTX clearance. Conversely, the impact of body surface area on MTX pharmacokinetics was weak, suggesting that dosing schedules based on body surface area were inadequate and potentially hazardous. A new LSS predicting accurately when the MTX concentration would reach 0.2 micromol/l has been validated; blood samples are stopped as soon as the MTX concentration drops to 1 micromol/l. With this LSS, our retrospective study suggests that 60% of the patients would have left the hospital earlier than they actually did owing to a better forecasting of the MTX decrease, thus improving their quality of life while improving the cost-effectiveness for the institute. HD-MTX can be administered safely using an adaptive-dosing strategy with drug monitoring. Moreover, pharmacokinetic modeling permits the accurate forecasting of the MTX elimination profile, thus allowing for a better management of the postinfusion care of cancer patients treated with particularly high doses of this drug.

A rapid and inexpensive method for anticipating severe toxicity to fluorouracil and fluorouracil-based chemotherapy.

Dihydropyrimidine dehydrogenase (DPD) deficiency leads to dramatic overexposure to fluorouracil (5-FU), resulting in a potentially lethal outcome in patients treated with standard doses. The aim of this study was to validate, in a routine clinical setting, a simple and rapid method to determine the DPD status in a subset of cancer patients, all presenting with life-threatening toxicities following 5-FU or capecitabine intake. In this study, 80 out of 615 patients (13%) suffered severe toxicities, including 5 lethal ones (0.8%), during or after chemotherapy with a fluoropyrimidine drug. Patients with severe toxicities were treated with 5-FU (76 patients) or capecitabine-containing protocols (4 patients). Simplified uracil to di-hydrouracil (U/UH2) ratio determination in plasma was retrospectively performed in these 80 patients, as a surrogate marker of DPD activity. When possible, 5-FU Css determination was performed, and screenings for the canonical IVS14+1G>A mutation were systematically carried out. Comparison of the U/UH2 ratios with a reference, non-toxic population, showed abnormal values suggesting impaired DPD activity in 57 out of the 80 toxic patients (71%) included in this study, and in 4 out of 5 patients (80%) with a fatal outcome. Similarly, drug exposures up to 15 times higher than the range observed in the non-toxic population were also observed. Importantly, no IVS14+1G>A mutation was found in these patients, including those displaying the most severe or lethal toxicities. These data warrant systematic detection of DPD-deficient patients prior to fluoropyrimidine administration, including when oral capecitabine (Xeloda) is scheduled. Finally, the simplified methodology presented here proved to be a low cost and rapid way to identify routinely patients at risk of toxicity with 5-FU or capecitabine.

Therapeutic drug monitoring for dose individualization of Cisplatin in testicular cancer patients based upon total platinum measurement in plasma.

Cisplatin (CDDP) is an anticancer agent widely used in testicular cancer, for which pharmacokinetic (PK)/pharmacodynamic relationships have usually been based upon measurement of its unbound fraction in plasma. Because it has been shown that free CDDP clearance can be related to patient's body surface area (BSA), dosage is mostly adjusted a priori using only this single parameter, with mixed results for accurately predicting CDDP exposure and reducing toxicities. In contrast, the authors present here an original, 5-day continuous infusion schedule, coupled to a daily Bayesian adaptive dosing with feedback strategy, based upon the rapid assay of total, rather than free, CDDP in plasma. Nineteen patients (66 therapeutic courses) were treated with platinum-based combinational therapy. Plasma samples were analyzed to allow real-time Bayesian estimation of individual PK parameters with subsequent prospective dose adjustment in order to reach a target Cmax (Cend) of 1.95 mg/L of total platinum. Performance of the Bayesian dosing method was evaluated by comparing target Cmax with achieved Cmax. The mean+/-SD Cmax achieved was 1.93+/-0.16 mg/L. No statistically significant difference was observed between experimental and target values (P>0.05, t test), and Cend achievement was done with an overall 6.6% precision, a performance to be compared with the initial 54% interpatient variability observed in CDDP clearance. A nonlinear mixed effect model population PK analysis was subsequently performed to identify retrospectively the covariates associated with PK parameters of total CDDP. It showed a good correlation (r=0.84, P=0.004) between total platinum clearance and therapeutic course number. A weaker correlation (r=0.59) was found between BSA and total CDDP clearance and, importantly, no additional relationship was established with BSA when successive therapeutic courses, and not only the first one, were considered. This highlights the critical importance of total drug accumulation on CDDP pharmacokinetics when several infusions are to be administered in a row and, therefore, the need for real-time dose individualization that takes into account the course number, rather than BSA. Finally, doses of CDDP administered during each course were significantly higher (+20%, P<0.01) than the ones classically normalized with BSA, thus leading to an overall greater drug exposure in the patients. It is noteworthy that despite these markedly higher doses, little severe toxicity was reported, and all of the patients presented in this study were still alive and disease free after a follow-up of up to 15 years.

Dose individualization of carboplatin after a 120-hour infusion schedule: higher dose intensity but fewer toxicities.

Carboplatin (CBDCA) is a widely used anticancer agent for which dose-effect and dose-toxicity relationships have been demonstrated, thus stressing the need for a controlled exposure to this drug. So far, carboplatin administration could only be individualized a priori following 2 classic methods, which are based on the evaluation of renal clearance: Calvert's and Chatelut's formulas. This study was designed to develop and evaluate the performance of an alternative CBDCA 120-hour schedule coupled to a Bayesian adaptive dosing with feedback strategy. Precision of the dosing method was assessed in 84 patients (256 courses performed during a 10-year period), by comparing CBDCA plasma concentrations observed at the end of the infusion with initial target values. A comprehensive monitoring of treatment-related toxicities also was performed. Finally, the authors compared doses actually delivered following the dose-tailoring method with the theoretical, standard, ones calculated retrospectively with Calvert's and Chatelut's formulas. No significant differences were found between experimental and theoretical concentrations. According to the target exposure chosen (3 levels), the mean doses administered to our patients were 517, 719, and 902 mg of CBDCA compared with 550, 509, and 538 or 657, 604, and 644 mg, which would have been given following Calvert or Chatelut formulas, respectively. These results showed that our Bayesian method led to the administration of up to 60% higher doses of carboplatin compared with those based only on the evaluation of renal clearance. Despite the markedly higher doses administered, no severe toxicities were reported in the patients treated following this new schedule. It is noteworthy that neither hematologic growth factors nor stem cells, usually associated with high-dose regimen, were used as support in this study. These data strongly suggest that it is possible to deliver higher dose- intensities of carboplatin, even in elderly, unselected patients, without increasing toxicities and with no growth factor support, provided that a therapeutic drug monitoring strategy with real-time tailored dosing is performed.

Toxic death-case after capecitabine + oxaliplatin (XELOX) administration: probable implication of dihydropyrimidine deshydrogenase deficiency.

This report here is the case of a 52-year-old male patient who suffered from extremely severe haematological toxicities (G4 neutropenia, G4 thrombocytopenia) while undergoing Xelox (Xeloda + Oxaliplatin) treatment for his multifocal hepatocarcinoma. Despite appropriate supportive treatment, his condition quickly deteriorated and led to death. It was hypothesized that dihydropyrimidine deshydrogenase (DPD) gene polymorphism could be, at least in part, responsible for this fatal outcome. To test this hypothesis, both phenotypic and genotypic studies were undertaken, and fully confirmed the DPD-deficient status of this patient. Uracil to dihydrouracil ratio in plasma was evaluated as a surrogate marker for DPD deficiency, and showed values out of the range previously recorded from a reference, non-toxic population. Interestingly, the canonical IVS14+1G>A single nucleotide polymorphism, usually associated with the most severe toxicities reported with 5-fluorouracil (5-FU), was not found in this patient, but further investigations showed instead a heterozygosity for the 1896C>T mutation located in the exon 14 of the DPYD gene. Taken together, the data strongly suggest for the first time that a toxic-death case after capecitabine-containing protocol could be, at least in part, linked with a DPD-deficiency syndrome. The case reported here warrants therefore systematic detection of patients at risk, including when oral capecitabine is scheduled.

Population pharmacokinetics of etoposide: application to therapeutic drug monitoring.

Antineoplastic agent etoposide (VP16) displays narrow therapeutic index and erratic pharmacokinetics, and dose individualization is a convenient way for overcoming the interpatient variability, so as to maintain the drug exposure within a therapeutic range. The authors proposed a population-based Bayesian methodology to adjust routinely VP16 dosage when given as a 5-day infusion. The mean VP16 pharmacokinetic parameters of the reference population calculated from 14 patients following the two-stage method were CL = 1.92 +/- 0.512 L/h and t(1/2) = 6.7 +/- 2 hours. The reference population was next used prospectively for Bayesian dose individualization for 25 patients (47 courses) undergoing 5-day infusions of VP16. Resulting steady-state concentrations proved to be successfully adjusted to the target values in 77% of the courses. Therefore, the method presented here meets the requirements for routine therapeutic drug monitoring of VP16, a major anticancer drug extensively used in clinical oncology.

Increase of CYP1B1 transcription in human keratinocytes and HaCaT cells after UV-B exposure.

Nonmelanoma skin cancers represent the most common malignant neoplasms in humans. UV-B play a major role in the etiology of these tumors, but exposure to environmental procarcinogens is also involved. CYP catalyzes numerous chemical carcinogen bioactivations and effects of UV-B on their expression are poorly understood. The aim of this study was to explore the molecular events involved in the induction of CYP1B1, a major cutaneous CYP, by UV-B. Our results demonstrated that unique UV-B exposure (20 mJ/cm(2)) increases human CYP1B1 transcript in primary keratinocytes and HaCaT cell cultures. Among 20 human samples studied, we observed a large interindividual variability of CYP1B1 mRNA induction (1.1- to 4.5-fold). Pretreatment with an antioxidant, N-acetylcysteine, repressed CYP1B1 increase, suggesting the involvement of UV-B photoproducts. alpha-Amanitin inhibition studies and CAT assays demonstrated that CYP1B1 mRNA induction is associated with a transcriptional activation of its expression. alpha-Naphthoflavone inhibition studies and CAT assays performed after directed mutagenesis of xenobiotic responsive element sites showed the involvement of Ah receptor. Taken together, these data demonstrated that UV-B induces CYP1B1 gene expression after an activation of its transcription, which involves Ah receptor.