In vitro studies of cutaneous retention of magnetic nanoemulsion loaded with zinc phthalocyanine for synergic use in skin cancer treatment

In this study was developed a new nano drug delivery system (NDDS) based on association of biodegradable surfactants with biocompatible magnetic fluid of maguemita citrate derivative. This formulation consists in a magnetic emulsion with nanostructured colloidal particles. Preliminary in vitro experiments showed that the formulation presents a great potential for synergic application in the topical release of photosensitizer drug (PS) and excellent target tissue properties in the photodynamic therapy (PDT) combined with hyperthermia (HPT) protocols. The physical chemistry characterization and in vitro assays were carried out by Zn(II) Phtalocyanine (ZnPc) photosensitizer incorporated into NDDS in the absence and the presence of magnetic fluid, showed good results and high biocompatibility. In vitro experiments were accomplished by tape-stripping protocols for quanti. cation of drug association with different skin tissue layers. This technique is a classical method for analyses of drug release in stratum corneum and epidermis+ dermis skin layers. The NDDS formulations were applied directly in pig skin (tissue model) fixed in the cell`s Franz device with receptor medium container with a PBS/EtOH 20% solution (10mM, pH 7.4) at 37 degrees C. After 12 h of topical administration stratum corneum was removed from fifty tapes and the ZnPc retained was evaluated by solvent extraction in dimetil-sulphoxide under ultrasonic bath. These results indicated that magnetic nanoemulsion (MNE) increase the drug release on the deeper skin layers when compared with classical formulation in the absence of magnetic particles. This could be related with the increase of biocompatibility of NDDS due to the great affinity for the polar extracelullar matrix in the skin and also for the increase in the drug partition inside of corneocites wall. (C) 2008 Elsevier B.V. All rights reserved.

The Scientific Basis for High-Intensity Interval Training: Optimising Training Programmes and Maximising Performance in Highly Trained Endurance Athletes

While the physiological adaptations that occur following endurance training in previously sedentary and recreationally active individuals are relatively well understood, the adaptations to training in already highly trained endurance athletes remain unclear. While significant improvements in endurance performance and corresponding physiological markers are evident following submaximal endurance training in sedentary and recreationally active groups, an additional increase in submaximal training (i.e. volume) in highly trained individuals does not appear to further enhance either endurance performance or associated physiological variables [e.g. peak oxygen uptake (V-dot O2peak), oxidative enzyme activity]. It seems that, for athletes who are already trained, improvements in endurance performance can be achieved only through high-intensity interval training (HIT). The limited research which has examined changes in muscle enzyme activity in highly trained athletes, following HIT, has revealed no change in oxidative or glycolytic enzyme activity, despite significant improvements in endurance performance (p < 0.05). Instead, an increase in skeletal muscle buffering capacity may be one mechanism responsible for an improvement in endurance performance. Changes in plasma volume, stroke volume, as well as muscle cation pumps, myoglobin, capillary density and fibre type characteristics have yet to be investigated in response to HIT with the highly trained athlete. Information relating to HIT programme optimisation in endurance athletes is also very sparse. Preliminary work using the velocity at which V-dot O2max is achieved (Vmax) as the interval intensity, and fractions (50 to 75%) of the time to exhaustion at Vmax (Tmax) as the interval duration has been successful in eliciting improvements in performance in long-distance runners. However, Vmax and Tmax have not been used with cyclists. Instead, HIT programme optimisation research in cyclists has revealed that repeated supramaximal sprinting may be equally effective as more traditional HIT programmes for eliciting improvements in endurance performance. Further examination of the biochemical and physiological adaptations which accompany different HIT programmes, as well as investigation into the optimal HIT programme for eliciting performance enhancements in highly trained athletes is required.

Effect of Cu Toxicity on Growth of Cowpea (Vigna unguiculata)

Accurate determination of the rhizotoxicity of Cu in dilute nutrient solutions is hindered by the difficulty of maintaining constant, pre-determined concentrations of Cu (micromolar) in solution. The critical Cu2+ activity associated with a reduction in the growth of solution-grown cowpea (Vigna unguiculata (L.) Walp. cv Caloona) was determined in a system in which Cu was maintained constant through the use of a cation exchange resin. The growth of roots and shoots was found to be reduced at solution Cu2+ activities ≥ 1.7 µM (corresponding to 90 % maximum growth). Although root growth was most likely reduced due to a direct Cu2+ toxicity, it is considered that the shoot growth reduction is attributable to a decrease in tissue concentrations of K, Ca, Mg, and Fe and the formation of interveinal chlorosis. At high Cu2+ activities, roots were brown in color, short and thick, had bent root tips with cracking of the epidermis and outer cortex, and had local swellings behind the roots tips due to a reduction in cell elongation. Root hair growth was reduced at concentrations lower than that which caused a significant reduction in overall root fresh weight.

Synthesis, structure and magnetism of the oxalato-bridged chromium(III) complex [NBu4n](4)[Cr-2(ox)(5)]center dot 2CHCl(3)

The binuclear complex [NBu4n](4)[Cr-2(ox)(5)]. 2CHCl(3) has been prepared by an ion-exchange procedure employing Dowex 50WX2 cation-exchange resin in the n-butylammonium form and potassium tris(oxalato)chromate(III). The dimeric complex was characterised by a crystal structure determination: monoclinic, space group C2/c, a = 29.241(7), b = 15.192(2), c = 22.026(5) Angstrom, beta = 94.07(1)degrees, Z = 4. The magnetic susceptibility (300-4.2 K) indicated that the chromium(III) sites were antiferromagnetically coupled (J = -3.1 cm(-1)).

Zinc potentiation of the glycine receptor chloride channel is mediated by allosteric pathways

Molecular mechanisms of zinc potentiation were investigated in recombinant human alpha 1 glycine receptors (GlyRs) by whole-cell patch-clamp recording and [H-3]strychnine binding assays. In the wild-type (WT) GlyR, 1 mu M zinc enhanced the apparent binding affinity of the agonists glycine and taurine and reduced their concentrations required for half-maximal activation. Thus, in the WT GlyR, zinc potentiation apparently occurs by enhancing agonist binding. However, analysis of GlyRs incorporating mutations in the membrane-spanning domain M1-M2 and M2-M3 loops, which are both components of the agonist gating mechanism, indicates that most mutations uncoupled zinc potentiation from glycine-gated currents but preserved zinc potentiation of taurine-gated currents. One such mutation in the M2-M3 loop, L274A, abolished the ability of zinc to potentiate taurine binding but did not inhibit zinc potentiation of taurine-gated currents. In this same mutant where taurine acts as a partial agonist, zinc potentiated taurine-gated currents but did not potentiate taurine antagonism of glycine-gated currents, suggesting that zinc interacts selectively with the agonist transduction pathway. The intracellular M246A mutation, which is unlikely to bind zinc, also disrupted zinc potentiation of glycine currents. Thus, zinc potentiation of the GlyR is mediated via allosteric mechanisms that are independent of its effects on agonist binding.

Synthesis and complexes of the sexidentate macrocycle 15-methyl-1,4,7,10,13-pentaazacyclohexadecan-15-amine

The potentially sexidentate polyamine macrocycle 15-methyl-1,4,7,10,13-pentaazacyclohexadecan-15-amine (1) was prepared via a copper(II)-templated route from 3,6,9-triazaundecan-1,ll-diamine, formaldehyde and nitroethane which first formed the copper(II) complex of the macrocycle 15-methyl-15-nitro-1,4,7,10,13-pentaazacyclohexadecane (2), reduced subsequently with zinc and aqueous acid to yield 1. The hexaamine 1, with five secondary amine groups in the macrocyclic ring and one pendant primary amine group, forms inert sexidentate octahedral complexes with cobalt(III), chromium(III) and iron(III). An X-ray structure of [Co(1)](ClO4)(3) defines the distorted octahedron of the complex cation and shows it is a symmetrical isomer with all nitrogens bound and the central aza group trans to the pendant primary amine group. The [M(1)](3+) ions are all stable indefinitely in aqueous solution and exhibit spectra consistent with MN6 d(3) (Cr), low-spin d(5) (Fe) and low-spin d(6) (Co) electronic ground states. For each complex, a reversible M(III/II) redox couple is observed. (C) 2000 Elsevier Science S.A. All rights reserved.

The Ni-II, Hg-II and Cu-II complexes of 12-membered-ring mixed-donor macrocycles

The structures of diaqua(1,7-dioxa-4-thia-10-azacyclododecane)nickel dinitrate, [Ni(C8H17NO2S)(H2O)(2)](NO3)(2), (I), bis(nitrato-O,O')(1,4,7-trioxa-10-azacyclododecane)mercury, [Hg(NO3)(2)(C8H17NO3)], (II), and aqua(nitrato-O)(1-oxa-4,7,10-triazacyclododecane)copper nitrate, [Cu(NO3)(C8H19N3O)(H2O)]NO3, (III), reveal each macrocycle binding in a tetradentate manner. The conformations of the ligands in (I) and (III) are the same and distinct from that identified for (II). These differences are in agreement with molecular-mechanics predictions of ligand conformation as a function of metal-ion size.

Cyclic octapeptides containing thiazole. Effect of stereochemistry and degree of flexibility on calcium binding properties

Solution conformation and calcium binding properties have been investigated for the two cyclic octapeptides cyclo(-D-Thr-D-Val(Thz)-Ile-)(2) (4) and cyclo(-Thr-Gly(Thz)-Ile-Ser-Gly(Thz)-Ile-)(5) and the results are compared to those for the cyclic octapeptides previously studied; ascidiacyclamide (1), patellamide D (2), cyclo(-Thr-D-Val(Thz)-Ile-)(2) (3), and cyclo(-Thr-D-Val-alphaAbu-Ile-)2 (6). Both 4 and 5 contain two heterocyclic thiazole ring constraints but the latter has a larger degree of flexibility as a consequence of the glycine residues within the cyclic framework. The solution conformation of 4 and 5 was determined from H-1 NMR spectra and found to be a twisted figure of eight similar to that for 2. Complexation studies using H-1 NMR and CD spectroscopy yielded 1 : 1 calcium-peptide binding constants (logK) for the two peptides (2.3 (4) and 5.7 (5)). For 5 the magnitude of the binding constant was verified by a competition titration using CD. The different calcium-binding affinities of 3 (logK = 4.0) and 4 is attributed to the stereochemistry of the threonine residue. The magnitude of the binding constant for 5 compared to 3 and 4 (all peptides containing two thiazole ring constrains) demonstrates that the increase in flexibility of the cyclic peptide has a dramatic effect on the Ca2+ binding ability. The affinity for Ca2+ thus decreases in the order (6 similar to 5 > 3 > 2 similar to 1 > 4). The number of carbonyl donors available on each peptide has only a limited effect on calcium binding. The most important factor is the flexibility, which allows for a conformation of the peptide capable of binding calcium efficiently.

Phase and microstructural evolution during the heat treatment of Sm-Ca-alpha-sialon ceramics

The phase and microstructural evolution of multi-cation Sm-Ca-alpha-sialon ceramics was investigated. Six samples were prepared, ranging from a pure Sm-sialon to a pure Ca-sialon, with calcium replacing samarium in 20 eq% increments, thus maintaining an equivalent design composition in all samples. After pressureless sintering at 1820 degreesC for 2 It, all samples were subsequently heat treated up to 192 h at 1450 and 1300 degreesC. The amount of grain boundary glass in the samples after sintering was observed to decrease with increasing calcium levels. A M-ss' or M-ss',-gehlenite solid solution was observed to form during the 1450 degreesC heat treatment of all Sm-containing samples, and this phase forms in clusters in the high-Sm samples. The thermal stability of the alpha-sialon phase was improved in the multi-cation systems. Heat treatment at 1300 degreesC produces SmAlO3 in the high-Sm samples, a M-ss',-gehlenite solid solution in the high-Ca samples, and a Sm-Ca-apatite phase in some intermediate samples. (C) 2002 Elsevier Science Ltd. All rights reserved.

α′ phase stability in Nd-Li-sialon systems

The formability and stability of the alpha-sialon (alpha') phase was investigated in multi-cation Nd-Li-sialon systems. Four samples were prepared, ranging from a pure Nd-sialon to a pure Li-sialon, with two intermediate samples being prepared with either lithium or neodymium replacing the other alpha'-stabilising additive by 20 eq.%, as to maintain an equivalent design composition in all samples. After sintering, all samples were subsequently heat treated up to 192 h at 1450 and 1300 degreesC. While significant quantities of the beta'-sialon (beta' phase were found in most samples, the high-lithium Li-Nd-sialon sample was found to be almost pure a' phase after sintering. Furthermore, the long-term stability of the a' phase on heat treatment was also found to be superior in both multi-cation samples than in either of the single-alpha'-stabilising-cation samples. This is thought to be related to improved retention of the lithium in the multi-cation systems, as much of the lithium was found to volatilise during sintering in the neodymium-free sample. (C) 2002 Elsevier Science Ltd. All rights reserved.

Conductivity, NMR and crystallographic study of N,N,N,N-tetramethylammonium dicyanamide plastic crystal phases: an archetypal ambient temperature plastic electrolyte material

N,N,N,N-Tetramethylammonium dicyanamide (Me(4)NDCA) has been examined via differential scanning calorimetry (DSC), thermogravimetric analysis, conductivity, single crystal X-ray diffraction and H-1 nuclear magnetic resonance (NMR) analyses, and was found to be highly conductive in the solid state (sigma = 10(-3) S cm(-2) at 420 K) and to also exhibit unusual plastic crystal behaviour. To investigate the correlation between such behaviour and the occurrence of molecular rotations in the crystal, H-1 NMR second moment measurements are compared with calculated values predicted from the crystal structure. While DSC analysis indicates a number of solid-solid transitions at ambient temperatures, subsequent H-1 NMR analysis of the Me4N+ cation shows that a variety of rotational motions become active at low (

Acidity and photolability of ruthenium salen nitrosyl and aquo complexes in aqueous solutions

The photochemical behavior of nitrosyl complexes Ru(salen)(NO)(OH(2))(+) and Ru(salen)(NO) Cl (salen = N, N`-ethylenebis-(salicylideneiminato) dianion) in aqueous solution is described. Irradiation with light in the 350-450 nm range resulted in nitric oxide (NO) release from both. For Ru(salen)(NO) Cl secondary photoreactions also resulted in chloride aquation. Thus, in both cases the final photoproduct is the diaquo cation Ru(III) (salen) (OH(2))(2)(+), for which pK(a)`s of 5.9 and 9.1 were determined for the coordinated waters. The pK(a) of the Ru(salen)(NO)(OH(2))+ cation was also determined as 4.5 +/- 0.1, and the relative acidities of these ruthenium aquo units are discussed in the context of the bonding interactions between Ru(III) and NO. (C) 2007 Elsevier B.V. All rights reserved.

Regulation by the exogenous polyamine spermidine of Na,K-ATPase activity from the gills of the euryhaline swimming crab Callinectes danae (Brachyura, Portunidae)

Euryhaline crustaceans rarely hyporegulates and employ the driving force of the Na,K-ATPase, located at the basal surface of the gill epithelium, to maintain their hemolymph osmolality within a range compatible with cell function during hyper-regulation. Since polyamine levels increase during the adaptation of crustaceans to hyperosmotic media, we investigate the effect of exogenous polyamines on Na,K-ATPase activity in the posterior gills of Callinectes danae, a euryhaline swimming crab. Polyamine inhibition was dependent on cation concentration, charge and size in the following order: spermine > spermidine > putrescine. Spermidine affected K-0.5 values for Na+ with minor alterations in K-0.5 values for K+ and N-H-4(+), causing a decrease in maximal velocities under saturating Na+, K+ and NH4+ concentrations. Phosphorylation measurements in the presence of 20 mu M ATP revealed that the Na,K-ATPase possesses a high affinity site for this substrate. In the presence of 10 mM Na+, both spermidine and spermine inhibited formation of the phosphoenzyme; however, in the presence of 100 mM Na+, the addition of these polyamines allowed accumulation of the phosphoenzyme. The polyamines inhibited pumping activity, both by competing with Na+ at the Na+-binding site, and by inhibiting enzyme dephosphorylation. These findings suggest that polyamine-induced inhibition of Na,K-ATPase activity may be physiologically relevant during migration to fully marine environments. (c) 2008 Elsevier Inc. All rights reserved.

Study of the antimicrobial peptide indolicidin and mutants in eukaryotic modelled membrane by molecular dynamics simulations

In this work the interaction of the antimicrobial peptide indolicidin (IND) and its mutants CP10A and CP11 with a eukaryotic membrane model was examined by molecular dynamics simulations. The aim was to analyse the behaviour of these antimicrobial peptides when they interact with a eukaryotic modelled membrane, thereby obtaining atomic detailed observations that are not experimentally available. In the simulations, the widely studied dipalmitoylphosphatidylcholine hydrated bilayer was used as a eukaryotic membrane model. In agreement with experimental observations, the peptides IND, CP10A, and CP11 insert into the bilayer differently; the peptides that insert more deeply present the major hemolytic activities. The hydrophobic residues are responsible for the insertion, but some Trp residues of the peptides remain at the bilayer/water interface because they interact with the bilayer choline groups by cation-pi interactions that should be important for recognition of eukaryotic membrane by the three studied peptides.

Refolding and purification of the human secreted group IID phospholipase A(2) expressed as inclusion bodies in Escherichia coli

The secreted phospholipases A(2) (sPLA(2)s) are water-soluble enzymes that bind to the surface of both artificial and biological lipid bilayers and hydrolyze the membrane phospholipids. The tissue expression pattern of the human group IID secretory phospholipase A(2) (hsPLA(2)-IID) suggests that the enzyme is involved in the regulation of the immune and inflammatory responses. With an aim to establish an expression system for the hsPLA(2)-IID in Escherichia coli, the DNA-coding sequence for hsPLA(2)-IID was subcloned into the vector pET3a, and expressed as inclusion bodies in E. coli (BL21). A protocol has been developed to refold the recombinant protein in the presence of guanidinium hydrochloride, using a size-exclusion chromatography matrix followed by dilution and dialysis to remove the excess denaturant. After purification by cation-exchange chromatography, far ultraviolet circular dichroism spectra of the recombinant hsPLA(2)-IID indicated protein secondary structure content similar to the homologous human group IIA secretory phospholipase A(2). The refolded recombinant hsPLA(2)-IID demonstrated Ca(2+)-dependent hydrolytic activity, as measuring the release free fatty acid from phospholipid liposomes. This protein expression and purification system may be useful for site-directed mutagenesis experiments of the hsPLA(2)-IID which will advance our understanding of the structure-function relationship and biological effects of the protein. (C) 2009 Elsevier Inc. All rights reserved.