Correlation of photodynamic activity and singlet oxygen quantum yields in two series of hydrophobic monocationic porphyrins

The photodynamic properties of eight hydrophobic monocationic methyl and ruthenium polypyridine complex derivatives of free-base and zinc(II) meso-triphenyl-monopyridylporphyrin series were evaluated and compared using HeLa cells as model. The cream-like polymeric nanocapsule formulations of marine atelocollagen/xanthan gum, prepared by the coacervation method, exhibited high phototoxicity but negligible cytotoxicity in the dark. Interestingly, the formulations of a given series presented similar photodynamic activities but the methylated free-base derivatives were significantly more phototoxic than the respective ruthenated photosensitizers, reflecting the higher photoinduced singlet oxygen quantum yields of those monocationic porphyrin dyes.

Comparative study on structure and magnetic properties of polycrystalline PrxY1-xBa2Cu3O7-delta prepared in oxygen and argon atmosphere

We report a systematic study on the influence of the synthesis routes on the structural and magnetic properties of polycrystalline PrxY1-xBa2Cu3O7-delta. We have prepared high-quality samples of this material by following a sol-gel method based on heat treatment in both inert argon and oxygen atmospheres in order to compare their effect on the formation of the superconducting phase using X-ray powder diffraction. Magnetic measurements (DC and AC susceptibility) clearly demonstrate that, for the same concentration of Pr, the superconducting transition temperature markedly increases in all samples prepared in argon atmosphere, including pure Pr-123. (C) 2012 Elsevier B.V. All rights reserved.

Effects of arterial oxygen tension and cardiac output on venous saturation: a mathematical modeling approach

OBJECTIVES: Hemodynamic support is aimed at providing adequate O-2 delivery to the tissues; most interventions target O-2 delivery increase. Mixed venous O-2 saturation is a frequently used parameter to evaluate the adequacy of O-2 delivery. METHODS: We describe a mathematical model to compare the effects of increasing O-2 delivery on venous oxygen saturation through increases in the inspired O-2 fraction versus increases in cardiac output. The model was created based on the lungs, which were divided into shunted and non-shunted areas, and on seven peripheral compartments, each with normal values of perfusion, optimal oxygen consumption, and critical O-2 extraction rate. O-2 delivery was increased by changing the inspired fraction of oxygen from 0.21 to 1.0 in steps of 0.1 under conditions of low (2.0 L.min(-1)) or normal (6.5 L.min(-1)) cardiac output. The same O-2 delivery values were also obtained by maintaining a fixed O-2 inspired fraction value of 0.21 while changing cardiac output. RESULTS: Venous oxygen saturation was higher when produced through increases in inspired O-2 fraction versus increases in cardiac output, even at the same O-2 delivery and consumption values. Specifically, at high inspired O-2 fractions, the measured O-2 saturation values failed to detect conditions of low oxygen supply. CONCLUSIONS: The mode of O-2 delivery optimization, specifically increases in the fraction of inspired oxygen versus increases in cardiac output, can compromise the capability of the "venous O-2 saturation" parameter to measure the adequacy of oxygen supply. Consequently, venous saturation at high inspired O-2 fractions should be interpreted with caution.

Study of the oxygen vacancy influence on magnetic properties of Fe- and Co-doped SnO2 diluted alloys

Transition-metal (TM)-doped diluted magnetic oxides (DMOs) have attracted attention from both experimental and theoretical points of view due to their potential use in spintronics towards new nanostructured devices and new technologies. In the present work, we study the magnetic properties of Sn0.96TM0.04O2 and Sn0.96TM0.04O1.98(V (O))(0.02), where TM = Fe and Co, focusing in particular in the role played by the presence of O vacancies nearby the TM. The calculated total energy as a function of the total magnetic moment per cell shows a magnetic metastability, corresponding to a ground state, respectively, with 2 and 1 mu(B)/cell, for Fe and Co. Two metastable states, with 0 and 4 mu(B)/cell were found for Fe, and a single value, 3 mu(B)/cell, for Co. The spin-crossover energies (E (S)) were calculated. The values are E (S) (0/2) = 107 meV and E (S) (4/2) = 25 meV for Fe. For Co, E (S) (3/1) = 36 meV. By creating O vacancies close to the TM site, we show that the metastablity and E (S) change. For iron, a new state appears, and the state with zero magnetic moment disappears. The ground state is 4 mu(B)/cell instead of 2 mu(B)/cell, and the energy E (S) (2/4) is 30 meV. For cobalt, the ground state is then found with 3 mu(B)/cell and the metastable state with 1 mu(B)/cell. The spin-crossover energy E (S) (1/3) is 21 meV. Our results suggest that these materials may be used in devices for spintronic applications that require different magnetization states.

Evaluation of Microbicidal Activity of Oxygen-Containing Plasmas using Biological Monitors with Different Lumen Calibers

New technologies and sterilization agents for heat-sensitive materials are under intense investigation. Plasma sterilization, an atoxic low-temperature substitute for conventional sterilization, uses various gases that are activated by an electrical discharge, generating reactive species that promote lethality in microorganisms. Here, assays were performed using pure O-2 and O-2 + H2O2 mixture gas plasmas against a standard load of Bacillus atrophaeus spores inoculated on glass carriers inside PVC catheters. The sterilization efficiency was studied as a function of plasma system (reactive ion etching or inductively coupled plasma), biological monitor lumen diameter, gas, radio frequency power, and sub-lethal exposition time. After sterilization, the biological monitors were disassembled and the surviving bacteria were grown in trypticase soy broth using the most probable number technique. Plasma antimicrobial activity depended on the catheter's internal diameter and radio frequency powers. The N-2 + H2O2 mixture exhibited higher microbial efficacy than pure N-2 in both plasma systems.

Short-term creatine supplementation decreases reactive oxygen species content with no changes in expression and activity of antioxidant enzymes in skeletal muscle

The effect of short-term creatine (Cr) supplementation upon content of skeletal muscle-derived-reactive oxygen species (ROS) was investigated. Wistar rats were supplemented with Cr (5 g/kg BW) or vehicle, by gavage, for 6 days. Soleus and extensor digitorum longus (EDL) muscles were removed and incubated for evaluation of ROS content using Amplex-UltraRed reagent. The analysis of expression and activity of antioxidant enzymes (superoxide dismutase 1 and 2, catalase and glutathione peroxidase) were performed. Direct scavenger action of Cr on superoxide radical and hydrogen peroxide was also investigated. Short-term Cr supplementation attenuated ROS content in both soleus and EDL muscles (by 41 and 33.7%, respectively). Cr supplementation did not change expression and activity of antioxidant enzymes. Basal TBARS content was not altered by Cr supplementation. In cell-free experiments, Cr showed a scavenger effect on superoxide radical in concentrations of 20 and 40 mM, but not on hydrogen peroxide. These results indicate that Cr supplementation decreases ROS content in skeletal muscle possibly due to a direct action of Cr molecule on superoxide radical.

Employing perichromism for probing the properties of carboxymethyl cellulose films: an expedient, accurate method for the determination of the degree of substitution of the biopolymer derivative

The properties of films of carboxymethyl cellulose, CMC, of different degree of substitution, DS, have been examined by the use of perichromic indicators (probes). The film properties that have been determined are: empirical polarity, E-T(33); "acidity", alpha; "basicity", beta; and dipolarity/polarizability, pi*. This has been achieved by employing the following perichromic probes: 4-nitroaniline, 4-nitroanisole, 4-nitro-N,N-dimethylaniline, and 2,6-dichloro-4-(2,4,6-triphenyl-pyridinium-1-yl)phenolate, WB. The correlations between both E-T(33)- or pi* and DS were found to be linear; that between beta and DS is a second order polynomial; no obvious correlation was found between alpha and DS. The polarities of CMC films are in the range of those of butyl alcohols. As models for CMC, we have employed cellulose plus CMC of high DS; oxidized cellulose with degree of oxidation = 0.5; sodium glucuronate. The former model behaved akin to CMC, but the plots of the perichromic properties versus DS showed different slopes/intercepts. FTIR data and molecular dynamics simulations on the solvation of WB have shown that this difference can be traced to more efficient hydrogen bonding between the film of the model and the probe. This affects the intra-molecular charge-transfer energy of the latter, leading to different responses to the variation of DS. Based on the excellent linear correlation between E-T(33) and DS, for CMC from different origins, we suggest that perichromism is a simple, accurate, and expedient alternative for the determination of DS of the biopolymer derivative.

On abstract differential equations with nonlocal conditions involving the temporal derivative of the solution

In this paper we discuss the existence of solutions for a class of abstract differential equations with nonlocal conditions for which the nonlocal term involves the temporal derivative of the solution. Some concrete applications to parabolic differential equations with nonlocal conditions are considered. (C) 2012 Royal Dutch Mathematical Society (KWG). Published by Elsevier B.V. All rights reserved.

Top spoilage losses in maize silage sealed with plastic films with different permeabilities to oxygen

The quality of plastic films used for horizontal silos is important to limit losses in the upper silage layer. The aim of this work was to study the effectiveness of different plastic films in reducing the top losses in maize silage. The following treatments were evaluated: (i) coextruded polyethylene/polyamide oxygen barrier film (OB), (ii) polyethylene film (PE), (iii) polyvinyl chloride film (PVC), and (iv) coextruded PE/polyvinyl alcohol film (PVOH). These treatments differed according to oxygen permeability with values of 75, 722, 982 and 289 cm(3) m(-2) per 24 hour respectively. OB and PVOH films had better temperature and fermentation profiles than the more permeable films. The OB film was effective in reducing the dry-matter (DM) losses during storage (82 g kg(-1)), and the PVOH film had an intermediate value of DM loss (101 g kg(-1)). PE and PVC films had higher losses (138 and 145 g kg(-1) respectively). Oxygen permeability of the films promoted a positive correlation with DM losses (P < 0.05; r2 = 0.945). The results indicate that O2 permeability through the plastic film is a crucial factor for maintaining silage quality in the upper layer of the silo when it is perfectly sealed.

Acellular dermal matrix graft with or without enamel matrix derivative for root coverage in smokers: a randomized clinical study

Aim: The aim of this randomized controlled clinical study was to compare the use of an acellular dermal matrix graft (ADMG) with or without the enamel matrix derivative (EMD) in smokers to evaluate which procedure would provide better root coverage. Material and Methods: Nineteen smokers with bilateral Miller Class I or II gingival recessions >= 3 mm were selected. The test group was treated with an association of ADMG and EMD, and the control group with ADMG alone. Probing depth, relative clinical attachment level, gingival recession height, gingival recession width, keratinized tissue width and keratinized tissue thickness were evaluated before the surgeries and after 6 months. Wilcoxon test was used for the statistical analysis at significance level of 5%. Results: No significant differences were found between groups in all parameters at baseline. The mean gain recession height between baseline and 6 months and the complete root coverage favored the test group (p = 0.042, p = 0.019 respectively). Conclusion: Smoking may negatively affect the results achieved through periodontal plastic procedures; however, the association of ADMG and EMD is beneficial in the root coverage of gingival recessions in smokers, 6 months after the surgery.

Hb S-Sao Paulo: A new sickling hemoglobin with stable polymers and decreased oxygen affinity

Hb S-Sao Paulo (SP) [HBB:c.20A > T p.Glu6Val: c.196A > G p.Lys65Glu] is a new double-mutant hemoglobin that was found in heterozygosis in an 18-month-old Brazilian male with moderate anemia. It behaves like Hb S in acid electrophoresis, isoelectric focusing and solubility testing but shows different behavior in alkaline electrophoresis, cation-exchange HPLC and RP-HPLC. The variant is slightly unstable, showed reduced oxygen affinity and also appeared to form polymers more stable than the Hb S. Molecular dynamics simulation suggests that the polymerization is favored by interfacial electrostatic interactions. This provides a plausible explanation for some of the reported experimental observations. (C) 2012 Elsevier Inc. All rights reserved.

(+)alpha-Tocopheryl succinate inhibits the mitochondrial respiratory chain complex I and is as effective as arsenic trioxide or ATRA against acute promyelocytic leukemia in vivo

The vitamin E derivative (+)alpha-tocopheryl succinate (alpha-TOS) exerts pro-apoptotic effects in a wide range of tumors and is well tolerated by normal tissues. Previous studies point to a mitochondrial involvement in the action mechanism; however, the early steps have not been fully elucidated. In a model of acute promyelocytic leukemia (APL) derived from hCG-PML-RAR alpha transgenic mice, we demonstrated that alpha-TOS is as effective as arsenic trioxide or all-trans retinoic acid, the current gold standards of therapy. We also demonstrated that alpha-TOS induces an early dissipation of the mitochondrial membrane potential in APL cells and studies with isolated mitochondria revealed that this action may result from the inhibition of mitochondrial respiratory chain complex I. Moreover, alpha-TOS promoted accumulation of reactive oxygen species hours before mitochondrial cytochrome c release and caspases activation. Therefore, an in vivo antileukemic action and a novel mitochondrial target were revealed for alpha-TOS, as well as mitochondrial respiratory complex I was highlighted as potential target for anticancer therapy. Leukemia (2012) 26, 451-460; doi:10.1038/leu.2011.216; published online 26 August 2011

Cytochrome c-promoted cardiolipin oxidation generates singlet molecular oxygen

The interaction of cytochrome c (cyt c) with cardiolipin (CL) induces protein conformational changes that favor peroxidase activity. This process has been correlated with CL oxidation and the induction of cell death. Here we report evidence demonstrating the generation of singlet molecular oxygen [O-2((1)Delta(g))] by a cyt c-CL complex in a model membrane containing CL. The formation of singlet oxygen was directly evidenced by luminescence measurements at 1270 nm and by chemical trapping experiments. Singlet oxygen generation required cyt c-CL binding and occurred at pH values higher than 6, consistent with lipid-protein interactions involving fully deprotonated CL species and positively charged residues in the protein. Moreover, singlet oxygen formation was specifically observed for tetralinoleoyl CL species and was not observed with monounsaturated and saturated CL species. Our results show that there are at least two mechanisms leading to singlet oxygen formation: one with fast kinetics involving the generation of singlet oxygen directly from CL hydroperoxide decomposition and the other involving CL oxidation. The contribution of the first mechanism was clearly evidenced by the detection of labeled singlet oxygen [O-18(2)((1)Delta(g))] from liposomes supplemented with 18-oxygen-labeled CL hydroperoxides. However quantitative analysis showed that singlet oxygen yield from CL hydroperoxides was minor (<5%) and that most of the singlet oxygen is formed from the second mechanism. Based on these data and previous findings we propose a mechanism of singlet oxygen generation through reactions involving peroxyl radicals (Russell mechanism) and excited triplet carbonyl intermediates (energy transfer mechanism).

DERIVATIVE SPECTROPHOTOMETRIC METHOD FOR DEYERMINATION OF ACYCLOVIR IN POLYMERIC NANOPARTICLES

A derivative spectrophotometric method was validated for quzintification of acyclovir in poly (n-butylcyanoacrylate) (PBCA) nanoparticles. Specificity, linearity. precision, accuracy, recovery. detection (LOD) and quantification (LOQ) Inuits were established for method validation. First-derivative it 295.2 nm eliminated interferences from nanoparticle ingredients and presented linearity for acyclovir concentrations ranging front 1.25 to 40.0 mu g/mL. (r = 0.9999). Precision and accuracy data demonstrated good reproducibility. Recovery ranged from 99.3 to 101.2. LOD) was 0.08 mu g/mL and LOQ. 0.25 mu g/mL. Thus. the proposed method proved to be easy. low cost. and accurate, and therefore, an useful alternative to quantify acyclovir in nanoparticles.

Cytometric quantification of singlet oxygen in the human malaria parasite Plasmodium falciparum

The malaria parasite Plasmodium falciparum proliferates within human erythrocytes and is thereby exposed to a variety of reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radical, superoxide anion, and highly reactive singlet oxygen (1O2). While most ROS are already well studied in the malaria parasite, singlet oxygen has been neglected to date. In this study we visualized the generation of 1O2 by live cell fluorescence microscopy using 3-(p-aminophenyl) fluorescein as an indicator dye. While 1O2 is found restrictively in the parasite, its amount varies during erythrocytic schizogony. Since the photosensitizer cercosporin generates defined amounts of 1O2 we have established a new cytometric method that allows the stage specific quantification of 1O2. Therefore, the parasites were first classified into three main stages according to their respective pixel-area of 200600 pixels for rings, 7001,200 pixels for trophozoites and 1,4002,500 pixels for schizonts. Interestingly the highest mean concentration of endogenous 1O2 of 0.34 nM is found in the trophozoites stage, followed by 0.20 nM (ring stage) and 0.10 nM (schizont stage) suggesting that 1O2 derives predominantly from the digestion of hemoglobin. (c) 2012 International Society for Advancement of Cytometry