Carbosilane Dendritic Amphiphiles from Cholesterol or Vitamin E for Micelle Formation

Cationic dendritic amphiphiles were prepared through the linkage of interesting hydrophobic molecules such as cholesterol or vitamin E to the focal point of carbosilane dendrons. These new dendritic systems self-assembled in saline, producing micellar aggregates with hydrodynamic diameters ranging from 6.5 to 9.2 nm, and critical micelle concentrations of approximately 5 and 10 μM for second- and third-generation systems, respectively. The assemblies were able to encapsulate drugs of different charges (anionic, neutral, and cationic). Surprisingly, a 92% encapsulation efficiency for diclofenac was achieved in micelles prepared from second-generation dendrons. Toxicity measurements on peripheral blood mononuclear cells indicated different behavior depending on the generation, corresponding to the micellar regime. In contrast to the third-generation system, the second-generation system was non-toxic up to 20 μM, opening a window for its use in a micellar regimen, thereby operating as a drug delivery system for different biomedical applications.

Emerging targets for cancer treatment: S100A9/RAGE

Developing better treatments that work for the majority of patients with brain metastasis (BM) is highly necessary. Complementarily, avoiding those therapeutic procedures that will not benefit a specific patient is also very relevant. In general, existing therapies for patients with BM could be improved in terms of molecular stratification and therapeutic efficacy. By questioning the benefit of whole brain radiotherapy as provided nowadays and the lack of biomarkers detecting radioresistance, we identified S100A9 and receptor for advanced glycation end-products (RAGE) as a liquid biopsy biomarker and a potential target for a radiosensitizer, respectively. Both of them are being clinically tested as part of the first comprehensive molecular strategy to personalized radiotherapy in BM.

P11.26.A STAT3 expression in brain metastases from breast cancer: correlations with different molecular subtypes and clinical outcome

Background

STAT3 expression in peritumoral reactive astrocytes (RA) of brain metastases (BM) may favor a pro-metastatic environment. The aim of the study was to evaluate in a retrospective cohort of surgically resected BM from breast cancer (BC) the expression of pSTAT3 in RA of peritumoral tissue of BM, identify different patterns of expression according to molecular subtypes, and correlate with intracranial progression-free survival (i-PFS).

Material and Methods

Patients with histologically proven BM diagnosis from BC were identified from the biobank of Pathology Unit of University of Turin and Spanish national BrM network (RENACER). pSTAT3 expression was evaluated and scored in RA of peritumoral tissue using GFAP and STAT3 immunohistochemistry, according to Priego et al. (Nat Med 2018). Data on histological diagnosis, molecular subtypes, and i-PFS were retrieved by chart review. Intracranial progression was defined based on MRI reports.

Results

Eighty-five BM specimens from BC of 85 female patients with a median age of 54 years (range 30-81 years) were available for analysis. Immunohistochemistry for GFAP and pSTAT3 was feasible in 68/85 (80%). Fifteen out of 68 patients (21.1%) had BM from luminal BC, 27/68 (39.7%) from HER2-positive BC, and 26/68 (39.2%) from TNBC. Fifty-six out of 68 (82.4%) showed positive staining of pSTAT3 in peritumoral RA, of which 9/68 (13.3%) scored with 3, 26/68 (38.2%) with 2, and 21/68 (30.9%%) with 1, while pSTAT3 expression was negative (score 0) in 12/68 (17.6%). High pSTAT3 expression (score 2-3) was observed in 17/27 (62.9%) BM from HER2-positive BC and in 15/26 (57.7%) BM from TNBC, while most of BM from luminal BC (12/15 - 80%) had low or absent pSTAT3 (score 0-1) (p=0.021). Overall i-PFS was 16 months (range 7-41): low pSTAT3 BM (score 0-1) had a median i-PFS of 21 months versus 12 months for high pSTAT3 BM (score 2-3). A shorter median i-PFS was observed in high pSTAT3 BM from TNBC (4 months) as compared with low pSTAT3 BM (11 months). Conversely, i-PFS of high pSTAT3 BM (7 months) was similar to low pSTAT3 BM (6 months) in HER2-positive BC.

Conclusion

pSTAT3 expression in RA of peritumoral tissue of BM from TNBC and HER2-positive BC is higher than in BM from luminal BC. Of note, patients with high pSTAT3 BM from TNBC progressed earlier in comparison with those with low pSTAT3, suggesting that pSTAT3 expression has an influence on the outcome.

OS06.7A METPlatform identifies brain metastasis vulnerabilities and predicts patient response to therapy

BACKGROUND

The diagnosis of brain metastasis involves high morbidity and mortality and remains an unmet clinical need in spite of being the most common tumor in the brain. Exclusion of these cancer patients from clinical trials is a major cause of their limited therapeutic options.

MATERIAL AND METHODS

We report a novel drug-screening platform (METPlatform) based on organotypic cultures which allows identifying effective anti-metastasis agents in the presence of the organ microenvironment. We have applied this approach to clinically relevant stages of brain metastasis using both experimental models and human tumor tissue (by performing patient-derived organotypic cultures - PDOCs -). We have also used METPlatform to perform unbiased proteomics of brain metastases in situ to identify potential novel mediators of this disease and explore resistance mechanisms to targeted therapy. Finally, we have exploited METPlatform as “avatars” to predict response to therapy in patients with primary brain tumors.

RESULTS

We identified heat shock protein 90 (HSP90) as a promising therapeutic target for brain metastasis. DEBIO-0932, a blood-brain barrier permeable HSP90 inhibitor, shows high potency against mouse and human brain metastases from different primary origin and oncogenomic profile at clinically relevant stages of the disease, including a novel model of local relapse after neurosurgery. Furthermore, in situ proteomic analysis of brain metastases treated with the chaperone inhibitor revealed non-canonical clients of HSP90 as potential novel mediators of brain metastasis and actionable mechanisms of resistance driven by autophagy. Combined therapy using HSP90 and autophagy inhibitors showed synergistic effects compared to sublethal concentrations of each monotherapy, demonstrating the potential of METPlatform to design and test rationale combination therapies to target metastasis more effectively. Finally, we show that brain tumor PDOCs predict the response of the corresponding patient to standard of care, thus proving the potential of METPlatform for improving personalized care in cancer.

CONCLUSION

Our work validates METPlatform as a potent resource for metastasis research integrating drug-screening and unbiased omic approaches that is fully compatible with human samples and questions the rationale of excluding patients with brain metastasis from clinical trials. We envision that METPlatform will be established as a clinically relevant strategy to personalize the management of metastatic disease in the brain and elsewhere.

P02.01 A strategy to personalize the use of radiation in patients with brain metastasis based on S100A9-mediated resistance

BACKGROUND

Finding effective treatment options for patients with brain metastasis remains an unmet need. Given the limitations imposed by the blood-brain-barrier for systemic approaches, radiotherapy offers a superior ability to access the brain. While clinical practice recently adapted the use of stereotactic radiosurgery (SRS), Whole-Brain-Radiotherapy (WBRT) continuous to be an important treatment option, since many patients present with multifocal lesions or bad performance scores, rendering them ineligible for SRS. Unfortunately, overall survival of patients remains unaffected by radiotherapy. Despite this clinical data, the molecular mechanisms that allow metastatic cells to resist radiotherapy in the brain is unknown.

MATERIAL AND METHODS

We have applied WBRT to experimental brain metastasis from lung and breast adenocarcinoma and validated their resistance in vivo.

RESULTS

An unbiased search to identify potential mediators of resistance identified the S100A9-RAGE-NFκB-JunB pathway. Targeting this pathway genetically reverts the resistance to radiotherapy and increases therapeutic benefits in vivo. In two independent cohorts of brain metastasis from lung and breast adenocarcinoma patients, levels of S100A9 correlate with the response to radiotherapy, offering a novel approach to stratify patients according to their expected benefit. In order to make this biomarker also available for brain metastasis patients receiving palliative WBRT without preceding surgery, we complemented our tumor-specimen based approach with the less invasive detection of S100A9 from liquid biopsies. Here, serum S100A9 also correlated with a worse response to WBRT in brain metastasis patients. Furthermore, we have validated the use of a blood-brain-barrier permeable RAGE inhibitor to restore radio-sensitivity in experimental brain metastasis models in vivo and in patient-derived organotypic cultures of radio-resistant brain metastasis ex vivo.

CONCLUSION

We identified S100A9 as a major mediator of radio-resistance in brain metastasis and offer the molecular framework to personalize radiotherapy by exploiting it as a biomarker and as a therapeutic target, thus maximizing the benefits for the patient.

Brain metastasis models: What should we aim to achieve better treatments?

Brain metastasis is emerging as a unique entity in oncology based on its particular biology and, consequently, the pharmacological approaches that should be considered. We discuss the current state of modelling this specific progression of cancer and how these experimental models have been used to test multiple pharmacologic strategies over the years. In spite of pre-clinical evidences demonstrating brain metastasis vulnerabilities, many clinical trials have excluded patients with brain metastasis. Fortunately, this trend is getting to an end given the increasing importance of secondary brain tumors in the clinic and a better knowledge of the underlying biology. We discuss emerging trends and unsolved issues that will shape how we will study experimental brain metastasis in the years to come.

Evaluation of pH-dependent amphiphilic carbosilane dendrons in micelle formation, drug loading and HIV-1 infection

New amphiphilic carbosilane dendrons with pH-dependent behaviour based on the presence of carboxylate (propionate or succinate) groups at their peripheries and a fatty acid at the focal point were developed. In the presence of salts, they were able to form micelles with critical aggregation concentrations increasing with increasing dendron generation. Their thermodynamic parameters were calculated from surface tension measurements and their diameters at different pHs were measured by dynamic light scattering. These micelles were stable at basic pH but degraded under acidic conditions. No significant differences were found for the propionate and succinate based dendron micelles at basic or acidic pH, but the succinate dendron assemblies were more stable at neutral pH. The properties of these systems as drug nano-carriers were studied using both hydrophilic and hydrophobic molecules, and the drug loading varied with the structure and charge of the drug. In addition, due to the presence of multiple negative charges, the dendrons exhibited anti-HIV activity. Higher generation dendrons with more peripheral carboxylates that were not assembled into micelles were more active than micelles composed of lower generation dendrons having fewer peripheral carboxylates.

Immunotherapy in NSCLC patients with brain metastases. Understanding brain tumor microenvironment and dissecting outcomes from immune checkpoint blockade in the clinic

BACKGROUND

Brain metastases are frequent complications in patients with non-small-cell lung cancer (NSCLC) associated with significant morbidity and poor prognosis. Our goal is to give a global overlook on clinical efficacy from immune checkpoint inhibitors in this setting and to review the role of biomarkers and molecular interactions in brain metastases from patients with NSCLC.

METHODS

We reviewed clinical trials reporting clinical outcomes of patients with NSCLC with brain metastases as well as publications assessing the tumor microenvironment and the complex molecular interactions of tumor cells with immune and resident cells in brain metastases from NSCLC biopsies or preclinical models.

RESULTS

Although limited data are available on immunotherapy in patients with brain metastases, immune checkpoint inhibitors alone or in combination with chemotherapy have shown promising intracranial efficacy and safety results. The underlying mechanism of action of immune checkpoint inhibitors in the brain niche and their influence on tumor microenvironment are still not known. Lower PD-L1 expression and less T CD8⁺ infiltration were found in brain metastases compared with matched NSCLC primary tumors, suggesting an immunosuppressive microenvironment in the brain. Reactive astrocytes and tumor associated macrophages are paramount in NSCLC brain metastases and play a role in promoting tumor progression and immune evasion.

CONCLUSIONS

Discordances in the immune profile between primary tumours and brain metastases underscore differences in the tumour microenvironment and immune system interactions within the lung and brain niche. The characterization of immune phenotype of brain metastases and dissecting the interplay among immune cells and resident stromal cells along with cancer cells is crucial to unravel effective immunotherapeutic approaches in patients with NSCLC and brain metastases.

Amphiphilic carbosilane dendrons as a novel synthetic platform toward micelle formation

A novel family of amphiphilic ionic carbosilane dendrons containing fatty acids at the focal point were synthesized and characterized. They spontaneously self-assembled in aqueous solution into micelles both in the absence and presence of salt, as confirmed by surface tension, conductivity, and DLS measurements. Dendron based micelles have spherical shapes and increase in size on decreasing dendron generation. These dendritic micelles have been demonstrated to be able to form complexes with therapeutic macromolecules such as siRNA and show a high loading capacity for drugs such as procaine, suggesting their potential use as nanocarriers for therapeutics.

Study of graphene dispersions in sodium dodecylsulfate by steady-state fluorescence of pyrene

HYPOTHESIS

Aqueous solutions of ionic surfactants allow the exfoliation of graphene, that can be explained considering the adsorption model of ionic surfactants to hydrophobic surfaces. For many years, pyrene has been used as a fluorescent probe because its sensitivity to the micro-environment. The study of pyrene fluorescence in the presence of different graphene dispersions in an ionic surfactant, would improve the knowledge of the graphene-surfactant interactions.

EXPERIMENTS

Different dispersions of graphene in sodium dodecylsulfate were prepared at different weight ratios 0.5, 1 and 2%. The dispersions have been studied by Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The influence of the dispersions on the pyrene fluorescence has been investigated.

FINDINGS

The graphene sheets modified by the surfactant quench the fluorescence of pyrene, which depends on the amount of graphene, the concentration of surfactant and the weight ratio. For surfactant concentrations below the critical micelle concentration, the quenching effect is higher as the weight ratio increases. Once this concentration is reached, the fluorescence increases slightly and then levels off. This behavior has been explained by the adsorption model. For a constant surfactant concentration, two straight lines can be observed in the Stern-Volmer plots whose cut-off point is approximately 20 mg L^-1 of graphene.

Comparison of Anionic, Cationic and Nonionic Surfactants as Dispersing Agents for Graphene Based on the Fluorescence of Riboflavin

Fluorescence quenching is a valuable tool to gain insight about dynamic changes of fluorophores in complex systems. Graphene (G), a single-layered 2D nanomaterial with unique properties, was dispersed in surfactant aqueous solutions of different nature: non-ionic polyoxyethylene-23-lauryl ether (Brij L23), anionic sodium dodecylsulphate (SDS), and cationic hexadecyltrimethylammonium bromide (CTAB) and dodecyltrimethylammonium bromide (DTAB). The influence of the surfactant type, chain length and concentration, G total concentration and G/surfactant weight ratio on the fluorescence intensity of vitamin B₂ (riboflavin) was investigated. The quality of the different G dispersions was assessed by scanning and transmission electron microscopies (SEM and TEM). A quenching phenomenon of the fluorescence of riboflavin was found for G dispersions in all the surfactants, which generally becomes stronger with increasing G/surfactant weight ratio. For dispersions in the ionic surfactants, the quenching is more pronounced as the surfactant concentration raises, whilst the non-ionic one remains merely unchanged for the different G/Brij L23 weight ratios. More importantly, results indicate that DTAB solutions are the optimum media for dispersing G sheets, leading to an up to 16-fold drop in the fluorescence intensity. Understanding the mechanism in fluorescence quenching of G dispersions in surfactants could be useful for several optical applications.

Cyclopentadienyl-based Mg complexes in the intramolecular hydroamination of aminoalkenes: mechanistic evidence for cationic versus neutral magnesium derivatives

Mechanistic evidence in the catalytic hydroamination of aminoalkenes for a cationic magnesium derivative.

Effect of fatty acids on self-assembly of soybean lecithin systems

With the increasing interest in natural formulations for drug administration and functional foods, it is desirable a good knowledge of the phase behavior of lecithin/fatty acid formulations. Phase structure and properties of ternary lecithin/fatty acids/water systems are studied at 37°C, making emphasis in regions with relatively low water and fatty acid content. The effect of fatty acid saturation degree on the phase microstructure is studied by comparing a fully saturated (palmitic acid, C16:0), monounsaturated (oleic acid, C18:1), and diunsaturated (linoleic acid, C18:2) fatty acids. Phase determinations are based on a combination of polarized light microscopy and small-angle X-ray scattering measurements. Interestingly, unsaturated (oleic acid and linoleic acid) fatty acid destabilizes the lamellar bilayer. Slight differences are observed between the phase diagrams produced by the unsaturated ones: small lamellar, medium cubic and large hexagonal regions. A narrow isotropic fluid region also appears on the lecithin-fatty acid axis, up to 8wt% water. In contrast, a marked difference in phase microsctructure was observed between unsaturated and saturated systems in which the cubic and isotropic fluid phases are not formed. These differences are, probably, a consequence of the high Krafft point of the C16 saturated chains that imply rather rigid chains. However, unsaturated fatty acids result in more flexible tails. The frequent presence of, at least, one unsaturated chain in phospholipids makes it very likely a better mixing situation than in the case of more rigid chains. This swelling potential favors the formation of reverse hexagonal, cubic, and micellar phases. Both unsaturated fatty acid systems evolve by aging, with a reduction of the extension of reverse hexagonal phase and migration of the cubic phase to lower fatty acid and water contents. The kinetic stability of the systems seems to be controlled by the unsaturation of fatty acids.

Dual effects of different selenium species on wheat

Wheat (Triticum aestivum) and its derivative products account for a major source of dietary intake of selenium (Se) in humans and animals, because of its essentiality due to its presence in vital enzymes. Se antioxidant role has resulted in the popularity of agronomic biofortification practises in Se deficient areas. Controlling Se uptake, metabolism, translocation and accumulation in plants will be important to decrease healthy risk of toxicity and deficiency and to help selecting adequate methods for biofortification. Selenate and selenite are the two main inorganic Se forms available in soil and in most of the studies are given separately. That study reveals that both Se species behave differently but combined the prevalent pattern is that of selenite; so it is taken up faster and it seems that interferes with selenate uptake and transport. Selenium has dual effects on wheat plants; at low concentrations it acts as growth stimulant whereas at high concentrations it reduces root elongation and biomass production and alters uptake and translocation of several essential nutrients.

Structure and phase equilibria of the soybean lecithin/PEG 40 monostearate/water system

PEG stearates are extensively used as emulsifiers in many lipid-based formulations. However, the scheme of the principles of the lipid-surfactant polymer interactions are still poorly understood and need more studies. A new phase diagram of a lecithin/PEG 40 monostearate/water system at 30 °C is reported. First, we have characterized the binary PEG 40 monostearate/water system by the determination of the critical micelle concentration value and the viscous properties. Then, the ternary phase behavior and the influence of phase structure on their macroscopic properties are studied by a combination of different techniques, namely, optical microscopy, small-angle X-ray scattering, differential scanning calorimetry, and rheology. The phase behavior is complex, and some samples evolve even at long times. The single monophasic regions correspond to micellar, swollen lamellar, and lamellar gel phases. The existence of extended areas of phase coexistence (hexagonal, cubic, and lamellar liquid crystalline phases) may be a consequence of the low miscibility of S40P in the lecithin bilayer as well as of the segregation of the phospholipid polydisperse hydrophobic chains. The presence of the PEG 40 monostearate has less effect in the transformation to the cubic phase for lecithin than that found in other systems with simple glycerol-based lipids.

Simulating an interacting gauge theory with ultracold Bose gases

We show how density dependent gauge potentials can be induced in dilute gases of ultracold atoms using light-matter interactions. We study the effect of the resulting interacting gauge theory and show how it gives rise to novel topological states in the ultracold gas. We find in particular that the onset of persistent currents in a ring geometry is governed by a critical number of particles. The density-dependent gauge potential is also found to support chiral solitons in a quasi-one-dimensional ultracold Bose gas.

On the assessment of hydroxyapatite fluoridation by means of Raman scattering

Hydroxyapatite is the main mineral component of bones and teeth. Fluorapatite, a bioceramic that can be obtained from hydroxyapatite by chemical substitution of the hydroxide ions with fluoride, exhibits lower mineral solubility and larger mechanical strength. Despite the widespread use of fluoride against caries, a reliable technique for unambiguous assessment of fluoridation in in vitro tests is still lacking. Here we present a method to probe fluorapatite formation in fluoridated hydroxyapatite by combining Raman scattering with thermal annealing. In synthetic minerals, we found that effectively fluoride substituted hydroxyapatite transforms into fluorapatite only after heat treatment, due to the high activation energy for this first order phase transition.

Structure of aggregates in diluted aqueous octyl glucoside/tetraethylene glycol monododecyl ether mixtures with different alkanols

A systematic study of the diluted lamellar phases of the OG/C(12)E(4) system with different alkanols has been carried out by small-angle X-ray scattering (SAXS). The measurements have been made as a function of both the concentration and the alcohol type. Several different form factor models have been used to estimate the differences in bilayer topology induced by the presence of alcohol. For the infinite lamellae form factor (with a high-low-high electronic density profile across the membrane), there is a good fitting of samples with a X(OG) = 0.1 ratios. Only the free parameters correspond to the pseudomolecule composition and hydration number, which resulted in two water molecules per ethylene oxide group in the polar head irrespective of the alkanol chain length and concentration. However, samples with higher OG content can be quite well fitted by a core-shell disk model. For the samples with higher OG content, we find the participation of OG in the disks to be important. From the line-shape analysis of SAXS data, the half-thickness of the hydrophobic layer and the thickness of the hydrophilic layer have also been obtained. The results suggest significant mixing of the surfactant acyl chains corresponding to both sides of the lamellae and the transition from vesicles to open bilayer fragments without macroscopic phase separation.

Migration of cortical interneurons relies on branched leading process dynamics

Migrating cells typically reach their targets in response to a relatively wide variety of extracellular molecules. Somehow surprisingly, most cells transduce these extracellular signals into a relatively homogeneous set of cellular changes that allow them to accurately find their target position. Here we summarize the characterization of the migratory behaviour of cortical interneurons in their journey to the cerebral cortex, which seems to represent a novel type of cellular adaptation during directional guidance. Similar to other migrating cells, cortical interneurons are highly polarized cells, with a prominent leading process and a short trailing process. However, the leading process of migrating interneurons continuously branches during the migratory cycle of these cells. Leading process branches are generated in response to the extracellular environment, and seem to serve as the main mechanism that determines the migratory direction for the cell. For each migratory cycle, the branch that is best oriented towards an attractive guidance cue will become stabilized, which in turn will allow the subcellular organelles and the nucleus to progress in the right direction. This migratory process is under the strict control, among several other molecules, of members from the small Rho GTPases family proteins. Pharmacological blocking of ROCKI/II abrogates the formation of leading process branches in migrating interneurons. The resulting cells, with a single leading process, do not efficiently modify their orientation in response to extracellular guidance cues, and so they fail to complete their migration.

Shear-induced topology changes in liquid crystals of the soybean lecithin/DDAB/water system

The viscoelastic behavior of the two different liquid crystalline lamellar phases and the liquid crystalline cubic phase of the mixed soybean lecithin/DDAB system in water was studied through rheology, with mechanical parameters studied as a function of composition. The swollen or diluted lamellar region is formed by vesicles, and its characteristic flow curve presents two-power law regions separated by a region where viscosity passes through a maximum. Yield stress and shear-dependent flow behavior were also observed. The microstructure suffers transformation under shear stress, and rheological response shifts from thixotropic to antithixotropic loops. Similar rheological behavior has been observed for samples in the collapsed or concentrated lamellar region, at the water-rich corner of the phase diagram. Vesicle formation may therefore occur by shearing the initial stacked and open bilayers. However, concentrated lamellar samples in the water-poor part of the phase diagram are less sensitive to shear effects and show plastic behavior and thixotropy. All lamellar samples manifest high elasticity. The dynamic responses of both lamellar topologies, i.e., vesicles and open bilayers, are comparable and exhibit an infinite relation time. The bicontinuous cubic, liquid crystalline phase is highly viscous. Its dynamic response cannot be modeled by a Maxwell model.

The effect of octyl glucoside on rheological behavior of diluted and concentrated lamellar phases

We have investigated the rheological properties of lamellar liquid crystal formed by nonionic surfactants at low and high surfactant concentrations with a small amount of octyl glucoside and their relationship with the topology of the bilayer. Rheology is a specific signature of each bilayer topology. The decrease in viscosity by increasing the shear rate according to a power law with exponent close to -0.8 was found for the concentrated system of LSB/1-butanol/water and 1% in weight of OG. On the contrary, the decrease in the viscosity by increasing the shear rate for the diluted system is less pronounced with lower exponent values. The rheological data agrees with the presence of vesicles. A special case is the system with benzyl alcohol. The apparent viscosity does not follow the same power law than for alkanols.

Influence of Concomitant Food Intake on the Excretion of Orally Administeredmyo-Inositol Hexaphosphate in Humans

myo-Inositol hexaphosphate (InsP6) widely occurs in plant seeds. At present, some important benefits of InsP6 for human health have been described. The purpose of this study was to find the best condition for the optimum absorption of orally administered InsP6, evaluated by InsP6 urinary excretion. The influence of different stomach conditions (empty, empty with an alkalinizing agent, and full stomach) on the effects of oral administration of InsP6 and its urinary excretion was investigated in six healthy subjects on an InsP6-poor diet, given 400 mg of calcium/magnesium salt of InsP6 as a single dose. The basal urinary excretion of InsP6 on an InsP6-poor diet (50.91 +/- 15.09 microg) was significantly lower than that found when an InsP6-normal diet was consumed (100.09 +/- 26.42 microg) (P < .05). No differences were observed in the areas under the curve of accumulated excretion at 8 hours among the three different stomach conditions studied, suggesting that the overall InsP6 absorption took place independently of the stomach state (full or fasted) and indicating that the InsP6 absorption also takes place during the intestinal transit. Thus, if InsP6 supplements of vegetal origin are consumed to maintain the optimum InsP6 levels needed for a healthy status, these supplements can be consumed either during or between meals with the same efficacy.

Effects of trace metals on the inhibition of calcium oxalate crystallization

The aim of this study was to examine the possible effects of some trace metals on the inhibition of calcium oxalate crystallization. A test of urinary lithogenic risk was used to follow the crystallization of calcium oxalate from artificial urine in the presence of several metal ions assayed in their physiological concentrations. Interactions of these metal ions with known inhibitors of such crystallization (phytate, pyrophosphate, citrate and chondroitin sulphate) were also investigated. None of the metals affected the inhibition of calcium oxalate crystallization at concentrations approximating those found in normal urine, with the exception of the Fe3+ ions. Interactions of Fe3+ with some urinary components produced both synergic (phytate and pyrophosphate) and negative (citrate) effects on preventing crystallization. These effects are explained in terms of the affinity of the inhibitors for the calcium oxalate crystal surface and their ability to form stable complexes in urine. Because of the minimal concentrations, we conclude that physiological concentrations of trace elements in urine have no significant influence on calcium oxalate crystallization. In this sense, ferric ions, which exhibit an intrinsic high inhibitory capacity of calcium oxalate crystallization at physiological concentrations, even increased by the concomitant presence of phytate and pyrophosphate, are probably unable to act as powerful inhibitors in the presence of physiological urinary concentrations of citrate, due to the formation of highly stable complexes in solution without inhibitory activity.

Determination of pollution trends in an abandoned mining site by application of a multivariate statistical analysis to heavy metals fractionation using SM&T-SES

The mobility, availability and persistence of Heavy Metals (HMs), As, Cd, Cu, Ni, Pb and Zn, in contaminated soils of a former abandoned mining area were evaluated by means of a sequential extraction scheme (SES) and applying a multivariate statistical analysis to the obtained data. Chemical partitioning of HMs in each sample was determined in four fractions (acid-soluble, reducible, oxidable and residual) following the Standard Measurements and Testing (SM&T) SES, formerly BCR-SES. Statistical evaluation of results by pattern recognition techniques allowed identification of groups of samples with similar characteristics and observations of correlations between variables, determining the pollution trends and distribution of HMs within the studied area. Typical metal-fraction association and metal availability characteristics of heavy metals have been depicted. The obtained results indicate an urgent need to attenuate the hazard in that area posed by high concentrations of toxic metals, which exceed the limits specified by different European legislations on soil reclamation.

Facilitated transport of Hg(II) through novel activated composite membranes

The results presented in this work deal with the prime application of activated composite membranes (ACMs) for the transport of Hg(II) ions in a continuous extraction-re-extraction system using di-(2-ethylhexyl)dithiophosphoric acid (DTPA) as carrier. The effects of variables such as the pH, the nature of the acid and the concentration of the casting solutions on the transport of Hg(II) are also investigated. When the ACM was prepared with a 0.5 M DTPA solution and when the feed solution contained 2.5x10(-4) M Hg(II) in 0.1 M HCl, the amount of mercury extracted was greater than 76%. The re-extracted mercury was subsequently recovered by means of a stripping phase comprising 0.3 M thiourea solution in 2 M H2SO4, yielding 54% of the initial amount of mercury after transport had taken place for 180 min.

Vascular activity of (-)-anonaine, (-)-roemerine and (-)-pukateine, three natural 6a(R)-1,2-methylenedioxyaporphines with different affinities for alpha1-adrenoceptor subtypes

We have studied the mechanism of action of three 6a( R)-1,2-methylenedioxyaporphines as vasorelaxant compounds. The alkaloids assayed showed different affinities for the three human cloned alpha (1)-adrenoceptor (AR) subtypes stably expressed in rat-1 fibroblasts, showing lower affinity for alpha(1B)-AR with regard to the alpha(1A)- or alpha(1D)-subtypes. These three natural compounds are more potent inhibitors of [ (3)H]-prazosin binding than of [ (3)H]-diltiazem binding to rat cerebral cortical membranes. As all these alkaloids inhibited noradrenaline (NA)-induced [ (3)H]-inositol phosphate formation in cerebral cortex and rat tail artery, they may be safely viewed as alpha (1)-AR antagonists, as is demonstrated by the vasorelaxant responses observed in isolated rat tail artery and/or aorta precontracted with NA. The alkaloids also inhibited the contractile response evoked by KCl (80 mM) but with a lower potency than that shown against NA-induced contraction. We have also examined their ability to inhibit the different forms of cyclic nucleotide phosphodiesterases (PDE) isolated from bovine aortic smooth muscle and endothelial cells, with negative results. We conclude that N-methylation favours the interaction of (R)-aporphines with all alpha (1)-AR subtypes, and that the topography of the binding site recognizing the basic or protonated nitrogen atom is similar in all three alpha (1)-AR subtypes. The presence of a hydroxy group at C-11 has different effects on the affinity for each alpha (1)-AR subtype but decreases the affinity for Ca (2+) channels. These results confirm and extend the view that subtle changes in the hydroxylation patterns on the aromatic ring of the aporphine structure affect the interactions of these compounds with the three alpha (1)-AR subtypes in different ways, suggesting that the binding site recognizing the aporphine skeleton is different in each of the three subtypes.

The effect of octyl glucoside on the lamellar phase of diluted C12E4 and alcohol systems

A systematic study on phase behavior of the mixture of nonionic surfactants with alcohols at 30.0+/-0.1 degrees C was carried out. The total surfactant concentration was kept to 0.1 M varying the mole ratio of n-octyl beta-d-glucopyranoside (OG) and tetraethylene glycol monododecyl ether. Two uniphasic regions were found, the lamellar phase at low OG mole fraction and micelles at high OG mole fraction. The presence of OG favors the lamellae-micelle transition. Alkanols and benzyl alcohol were used as cosurfactants. The more hydrophobic alcohols (octanol and decanol) increase the OG content in the mixed bilayers. On the contrary, benzyl alcohol is not as favorable to the OG incorporation in the lamellar phase as in the mixed micelles. The L(3) phase has only been found as a uniphasic region with hexanol.

The effect of resin particle size on the rate of ion release: interactions in mixed bed systems

The aim of the present study is to evaluate the influence of resin particle sizes on the rate of ions release from a mixture of ion-exchange resins (named NMTD) which supplies calcium, fluoride, and phosphate ions as the main mineral content, and to elucidate the different phenomena taking place through the related ion-exchange process. The final goal of the study, related to dental application (enamel restoration), is to limit the particle size range, since the rate of ion release is a key parameter in the successful achievement of such objective. Weak-type ion-exchange resins, loaded with the appropriate ions, were ground and sieved into granulometric fractions of bead diameters of 0.1-0.075, 0.075-0.063, and 0.063-0.05 mm. Particle size was controlled by a laser diffraction particle distribution analyzer. The experiments on the kinetics of ions release were carried out under batch conditions in artificial saliva desorption solution thermostatized at 37 degrees C. The release of Ca(2+) and F(-) was determined by corresponding ion-selective electrodes automatically controlled, whereas H(2)PO(4)(-) was measured spectrophotometrically by the inductively coupled plasma-optical emission technique (ICP-OES). The results of this study show that the process of ion-exchange for the different particle size fractions of resins is critical for the study of the kinetics release of the ions immobilized in the corresponding mixed bed polymeric matrices. In fact, despite the apparent narrow range of particle sizes of the mixed bed systems studied, appreciable differences in the rate of ions release are obtained. Since the ion release rate is depending on the contact surface, an increase of factor of 2 in particle size represents an increase of an order of magnitude of the resin contact surface due to the resin porosity. In this concern, it has been observed that the rate of ions release increases when particle size decreases. The interactions occurring during the ion release from the mixed bed resins (containing calcium-, fluoride-, and phosphate-loaded resins) can be interpreted by the following phenomena: H(2)PO(4)(-), which hardly modifies its rate of release in the presence of Ca(2+) and F(-) in the mixture, promotes a considerable increase in the rate of Ca(2+) release due to the formation of a calcium dihydrogen phosphate soluble complex. F(-) also produces an acceleration in the rate of Ca(2+) release due to the formation of solid CaF(2 )on the surface of cationic resin particles, which in contrast leads to a decrease in the rate of F(-) release.