An Inter-Cooperative Biohybrid Platform to Enable Tumor Ablation and Immune Activation

A biohybrid therapeutic system, consisting of responsive materials and living microorganisms with inter-cooperative effects, is designed and investigated for tumor treatment. In this biohybrid system, S2 O3 2- -intercalated CoFe layered double hydroxides (LDH) are integrated at the surface of Baker's yeasts. Under the tumor microenvironment, functional interactions between yeast and LDH are effectively triggered, resulting in S2 O3 2- release, H2 S production, and in-situ generation of highly catalytic agents. Meanwhile, the degradation of LDH in the tumor microenvironment induces the exposure of the surface antigen of yeast, leading to effective immune activation at the tumor site. By virtue of the inter-cooperative phenomena, this biohybrid system exhibits significant efficacy in tumor ablation and strong inhibition of recurrence. This study has potentially offered an alternative concept by utilizing the metabolism of living microorganisms and materials in exploring effective tumor therapeutics.

Sources and levels of copper affect liver copper profile, intestinal morphology and cecal microbiota population of broiler chickens fed wheat-soybean meal diets

Super dosing copper (Cu) has long been used as an alternative to antibiotic growth-promoters in broiler chickens' diet to improve gut health. This study was designed to compare nutritional and growth-promoting levels of Cu hydroxychloride (CH) with CuSO4 on gut health bio-markers and liver mineral profile of broiler chickens. Ross 308 chicks (n = 864) were randomly assigned to eight treatments, as basal diet containing no supplemental Cu; the basal diet with 15 or 200 mg/kg Cu as CuSO4; or 15, 50, 100, 150 or 200 mg/kg Cu from CH. The highest liver Cu content was observed in birds fed the diets with 200 mg/kg CuSO4 (P < 0.01). Serum FITC-d concentration as the leaky gut marker, and liver malondialdehyde concentration were not affected. Copper level or source had no effect on cecal short chain fatty acid and the mRNA expression of five jejunal genes involved in gut integrity. Negative linear responses of Cu were observed on Lactobacillus (P = 0.032), Bacteroides (P = 0.033), and Enterobacteriaceae (P = 0.028) counts. The jejunal villus height increased in birds fed CH at 200 and 100 mg/kg (P < 0.05). Increasing Cu levels, linearly and quadratically (P < 0.001), increased Cu excretion.

MgFe-LDH Nanoparticles: A Promising Leukemia Inhibitory Factor Replacement for Self-Renewal and Pluripotency Maintenance in Cultured Mouse Embryonic Stem Cells

Leukemia inhibitory factor (LIF), an indispensable bioactive protein that sustains self-renewal and pluripotency in stem cells, is vital for mouse embryonic stem cell (mESC) culture. Extensive research is conducted on reliable alternatives for LIF as its clinical application in stable culture and large-scale expansion of ESCs is limited by its instability and high cost. However, few studies have sought to replace LIF with nanoparticles to provide a xeno-free culture condition. MgAl-LDH (layered double hydroxide) nanoparticles can partially replace LIF in maintaining pluripotency of mESCs; however, the requirement and tolerance for aluminum ions in mice are far lesser than those of iron ions. Hence, MgFe-LDH nanoparticles are selected for this study. MgFe-LDH is superior to MgAl-LDH in maintaining self-renewal and pluripotency of mESCs, in the absence of LIF and mouse embryonic fibroblast. Furthermore, combined transcriptomic and proteomic analysis confirms that MgFe-LDH can activate the LIF receptor (LIFR)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B(AKT), LIFR/JAK/janus kinase (JAK)/signal transducer and activator of transcription 3(STAT3), and phospho-signal transducer and activator of transcription 3(p-STAT3)/ten-eleven translocation (TET) signaling pathways, while the extra Fe2+ provided by MgFe-LDH would also enhance TET1/2 abundance thus affecting the TET1/2 regulated pluripotency related marker expression and TET1/2 meditated DNA demethylation. These results suggest that MgFe-LDH nanoparticles can thus be used as an affordable and efficient replacement for LIF in mESC cultivation.

Near-Infrared-Activated Lysosome Pathway Death Induced by ROS Generated from Layered Double Hydroxide-Copper Sulfide Nanocomposites

The overdeveloped lysosomes in cancer cells are gaining increasing attention toward more precise and effective organelle-targeted cancer therapy. It is suggested that rod/plate-like nanomaterials with an appropriate size exhibited a greater quantity and longer-term lysosomal enrichment, as the shape plays a notable role in the nanomaterial transmembrane process and subcellular behaviors. Herein, a biodegradable platform based on layered double hydroxide-copper sulfide nanocomposites (LDH-CuS NCs) is successfully prepared via in situ growth of CuS nanodots on LDH nanoplates. The as-prepared LDH-CuS NCs exhibited not only high photothermal conversion and near-infrared (NIR)-induced chemodynamic and photodynamic therapeutic efficacies, but also could achieve real-time in vivo photoacoustic imaging (PAI) of the entire tumor. LDH-CuS NCs accumulated in lysosomes would then generate extensive subcellular reactive oxygen species (ROS) in situ, leading to lysosomal membrane permeabilization (LMP) pathway-associated cell death both in vitro and in vivo.

Fungicide application increased copper-bioavailability and impaired nitrogen fixation through reduced root nodule formation on alfalfa

Copper-based fungicides have been used for a long time in viticulture and have accumulated in many vineyard soils. In this study, incrementing Cu(OH)₂-based fungicide application from 0.05 to 5 g Cu kg^-1 on two agricultural soils (an acidic sandy loam (L, pH 4.95) and an alkaline silt loam (D, pH 7.45)) resulted in 5 times more mobile Cu in the acidic soil. The most sensitive parameters of alfalfa (Medicago sativa) growing in these soils were the root nodule number, decreasing to 34% and 15% of the control at 0.1 g Cu kg^-1 in soil L and at 1.5 g Cu kg^-1 in soil D, respectively, as well as the nodule biomass, decreasing to 25% and 27% at 0.5 g Cu kg^-1 in soil L and at 1.5 g Cu kg^-1 in soil D, respectively. However, the enzymatic N₂-fixation was not directly affected by Cu in spite of the presence of Cu in the meristem and the zone of effective N₂-fixation, as illustrated by chemical imaging. The strongly different responses observed in the two tested soils reflect the higher buffering capacity of the alkaline silt loam and showed that Cu mitigation and remediation strategies should especially target vineyards with acidic, sandy soils.

Pretreating anaerobic fermentation liquid with calcium addition to improve short chain fatty acids extraction via in situ synthesis of layered double hydroxides

In situ synthesis of layered double hydroxides (LDHs) was proved to be an effective way to extract short chain fatty acids (SCFAs) from anaerobic fermentation liquid (AFL) as carbon source for biodenitrification, but the SCFAs content in SCFAs-LDH was unsatisfactory because of the existence of much carbonate in AFL. Pretreatment of AFL with calcium addition was investigated to remove carbonate and improve SCFAs extraction via LDHs synthesis. Results of batch tests showed that, the carbonate removal efficiency was as high as 76.6% when the calcium addition was 0.06 mol/L at pH 12. When using the optimal SCFAs/Al³⁺ ratio of 3.0, the total SCFAs content in SCFAs-LDH with pretreatment was improved to 46.5 mg COD/g LDH, which was 4.5 times of the control (10.4 mg COD/g LDH). These results suggest that adding calcium to AFL was an effective way to eliminate the negative effect of carbonates on SCFAs-LDH synthesis.

Ladderane phospholipids form a densely packed membrane with normal hydrazine and anomalously low proton/hydroxide permeability

Ladderane lipids are unique to anaerobic ammonium-oxidizing (anammox) bacteria and are enriched in the membrane of the anammoxosome, an organelle thought to compartmentalize the anammox process, which involves the toxic intermediate hydrazine (N2H4). Due to the slow growth rate of anammox bacteria and difficulty of isolating pure ladderane lipids, experimental evidence of the biological function of ladderanes is lacking. We have synthesized two natural and one unnatural ladderane phosphatidylcholine lipids and compared their thermotropic properties in self-assembled bilayers to distinguish between [3]- and [5]-ladderane function. We developed a hydrazine transmembrane diffusion assay using a water-soluble derivative of a hydrazine sensor and determined that ladderane membranes are as permeable to hydrazine as straight-chain lipid bilayers. However, pH equilibration across ladderane membranes occurs 5-10 times more slowly than across straight-chain lipid membranes. Langmuir monolayer analysis and the rates of fluorescence recovery after photobleaching suggest that dense ladderane packing may preclude formation of proton/hydroxide-conducting water wires. These data support the hypothesis that ladderanes prevent the breakdown of the proton motive force rather than blocking hydrazine transmembrane diffusion in anammox bacteria.

Cyamopsis tetragonoloba type 1 metallothionein (CtMT1) gene is upregulated under drought stress and its protein product has an additional C-X-C motif and unique metal binding pattern

Metallothioneins (MTs) are involved in cellular homeostasis of essential metal ions and detoxification of nonessential metal ions. We report here the identification of four MT genes, CtMT1, CtMT2, CtMT3 and CtMT4, encoding CtMT1, CtMT2, CtMT3 and CtMT4 proteins, respectively, from the industrial guar crop. The primary structures of last three proteins were similar to those of respective MT proteins of other plants but the CtMT1 protein primary structure was different from the other plant MT1 proteins in having an additional C-X-C motif. The four MT genes showed tissue specific expression patterns suggesting their specific roles in different tissues. High expression of CtMT1 gene was observed in roots and nodules whereas CtMT2 and CtMT3 genes showed high expression in leaves. The expression of CtMT4 gene was high in seeds. The qRT-PCR studies revealed upregulation in expression of CtMT1 gene under drought stress. Recombinant CtMT1 protein was produced in E. coli Rosetta cells and purified by metal affinity chromatography. The purified protein showed antioxidant property and the order of its metal ion binding affinities was Cu²⁺ > Zn²⁺ > Fe²⁺ > Cd²⁺. This information about CtMT1 protein is expected to be useful in understanding its role in drought tolerance and other physiological processes of guar.

Surface pH changes suggest a role for H+/OH- channels in salinity response of Chara australis

To understand salt stress, the full impact of salinity on plant cell physiology has to be resolved. Electrical measurements suggest that salinity inhibits the proton pump and opens putative H+/OH- channels all over the cell surface of salt sensitive Chara australis (Beilby and Al Khazaaly 2009; Al Khazaaly and Beilby 2012). The channels open transiently at first, causing a characteristic noise in membrane potential difference (PD), and after longer exposure remain open with a typical current-voltage (I/V) profile, both abolished by the addition of 1 mM ZnCl2, the main known blocker of animal H+ channels. The cells were imaged with confocal microscopy, using fluorescein isothiocyanate (FITC) coupled to dextran 70 to illuminate the pH changes outside the cell wall in artificial fresh water (AFW) and in saline medium. In the early saline exposure, we observed alkaline patches (bright fluorescent spots) appearing transiently in random spatial distribution. After longer exposure, some of the spots became fixed in space. Saline also abolished or diminished the pH banding pattern observed in the untreated control cells. ZnCl2 suppressed the alkaline spot formation in saline and the pH banding pattern in AFW. The osmotic component of the saline stress did not produce transient bright spots or affect banding. The displacement of H+ from the cell wall charges, the H+/OH- channel conductance/density, and self-organization are discussed. No homologies to animal H+ channels were found. Salinity activation of the H+/OH- channels might contribute to saline response in roots of land plants and leaves of aquatic angiosperms.

Foliar Exposure of Cu(OH)2 Nanopesticide to Basil ( Ocimum basilicum): Variety-Dependent Copper Translocation and Biochemical Responses

In this study, low and high anthocyanin basil ( Ocimum basilicum) varieties (LAV and HAV) were sprayed with 4.8 mg Cu/per pot from Cu(OH)₂ nanowires, Cu(OH)₂ bulk (CuPro), or CuSO₄ and cultivated for 45 days. In both varieties, significantly higher Cu was determined in leaves of CuSO₄ exposed plants (691 and 672.6 mg/kg for LAV and HAV, respectively); however, only in roots of HAV, Cu was higher, compared to control ( p ≤ 0.05). Nanowires increased n-decanoic, dodecanoic, octanoic, and nonanoic acids in LAV, but reduced n-decanoic, dodecanoic, octanoic, and tetradecanoic acids in HAV, compared with control. In HAV, all compounds reduced eugenol (87%), 2-methylundecanal (71%), and anthocyanin (3%) ( p ≤ 0.05). In addition, in all plant tissues, of both varieties, nanowires and CuSO₄ reduced Mn, while CuPro increased chlorophyll contents, compared with controls ( p ≤ 0.05). Results suggest that the effects of Cu(OH)₂ pesticides are variety- and compound-dependent.

Key Roles of Size and Crystallinity of Nanosized Iron Hydr(oxides) Stabilized by Humic Substances in Iron Bioavailability to Plants

Availability of Fe in soil to plants is closely related to the presence of humic substances (HS). Still, the systematic data on applicability of iron-based nanomaterials stabilized with HS as a source for plant nutrition are missing. The goal of our study was to establish a connection between properties of iron-based materials stabilized by HS and their bioavailability to plants. We have prepared two samples of leonardite HS-stabilized iron-based materials with substantially different properties using the reported protocols and studied their physical chemical state in relation to iron uptake and other biological effects. We used Mössbauer spectroscopy, XRD, SAXS, and TEM to conclude on iron speciation, size, and crystallinity. One material (Fe-HA) consisted of polynuclear iron(III) (hydr)oxide complexes, so-called ferric polymers, distributed in HS matrix. These complexes are composed of predominantly amorphous small-size components (<5 nm) with inclusions of larger crystalline particles (the mean size of (11 ± 4) nm). The other material was composed of well-crystalline feroxyhyte (δ'-FeOOH) NPs with mean transverse sizes of (35 ± 20) nm stabilized by small amounts of HS. Bioavailability studies were conducted on wheat plants under conditions of iron deficiency. The uptake studies have shown that small and amorphous ferric polymers were readily translocated into the leaves on the level of Fe-EDTA, whereas relatively large and crystalline feroxyhyte NPs were mostly sorbed on the roots. The obtained data are consistent with the size exclusion limits of cell wall pores (5-20 nm). Both samples demonstrated distinct beneficial effects with respect to photosynthetic activity and lipid biosynthesis. The obtained results might be of use for production of iron-based nanomaterials stabilized by HS with the tailored iron availability to plants. They can be applied as the only source for iron nutrition as well as in combination with the other elements, for example, for industrial production of "nanofortified" macrofertilizers (NPK).

Layered Double Hydroxides: Potential Release-on-Demand Fertilizers for Plant Zinc Nutrition

A novel zinc (Zn) fertilizer concept based on Zn-doped layered double hydroxides (Zn-doped Mg-Fe-LDHs) has been investigated. Zn-doped Mg-Fe-LDHs were synthesized, their chemical composition was analyzed, and their nutrient release was studied in buffered solutions with different pH values. Uptake of Zn by barley (Hordeum vulgare cv. Antonia) was evaluated in short- (8 weeks), medium- (11 weeks), and long-term (28 weeks) experiments in quartz sand and in a calcareous soil enriched with Zn-doped Mg-Fe-LDHs. The Zn release rate of the Zn-doped Mg-Fe-LDHs was described by a first-order kinetics equation showing maximum release at pH 5.2, reaching approximately 45% of the total Zn content. The Zn concentrations in the plants receiving the LDHs were between 2- and 9.5-fold higher than those in plants without Zn addition. A positive effect of the LDHs was also found in soil. This work documents the long-term Zn release capacity of LDHs complying with a release-on-demand behavior and serves as proof-of-concept that Zn-doped Mg-Fe-LDHs can be used as Zn fertilizers.

Agronomic Effectiveness of Granulated and Powdered P-Exchanged Mg-Al LDH Relative to Struvite and MAP

Layered double hydroxides (LDHs) used to recover P from wastewater have recently been proposed as new slow-release fertilizers. Here, the use of P-exchanged Mg-Al LDHs as powdered or granulated fertilizer is explored and compared with monoammonium phosphate (MAP), a fully water-soluble fertilizer, and with struvite, a recycled phosphate fertilizer with lower solubility. First, these three fertilizers were compared in a 100-day incubation experiment using P diffusion visualization and chemical analysis to assess P release from either granules or powdered fertilizer in three different soils. By the end of the incubation, 74-90% of P remained within the LDH granule, confirming a slow release. Second, a pot experiment was performed with wheat (Triticum aestivum) in an acid and a calcareous soil. The granular treatment resulted in a considerably higher P uptake for MAP compared to LDH and struvite. For the powder treatments, the P uptake was less than for granular MAP and was largely unaffected by the chemical form. The LDHs and struvite showed a lower agronomic effectiveness than granular MAP, but the benefits of their use in P recycling, potential residual value, and environmental benefits may render these slow-release fertilizers attractive.

Spectroscopic Investigations of Catalase Compound II: Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme

We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pKa = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pKa in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules.

Effects of sub-acute methanol extract treatment of Calliandra portoricensis root bark on antioxidant defence capacity in an experimental rat model

BACKGROUND

The attendant side effects associated with some synthetic drugs used in the management of diseases have led to the search for safer alternative therapies that are relatively cheaper with minimal side effects.

METHODS

The methanol extract of Calliandra portoricensis root bark (CPRB) was orally administered at the doses of 5, 10, 20, and 25 mg/kg body weight for 14 consecutive days of 5 rats in each group. The control rats were given distilled water.

RESULTS

The 95% methanol extract of CPRB significantly (p<0.05) scavenged NO• and OH• radicals compared to vitamin C. The level of lipid peroxidative products (malondialdehyde, MDA) was significantly (p<0.05) attenuated in a dose-dependent manner. Antioxidant enzymes including superoxide dismutase and catalase were significantly (p<0.05) exercabated in both liver and kidney in a dose-dependent manner. Furthermore, serum AST, alanine aminotransaminase and γ-glutamyltransferase (GGT) activity depicted non-significant (p>0.05) increase in the treated animals. The histological examination showed mild vacuolar, portal congestion and cell infiltration by mononuclear of the hepatic tissues.

CONCLUSIONS

The study then concluded that a therapeutic dose of the methanol extract of CPRB triggered the antioxidant defence systems in male rats. It is, therefore, recommended that the doses should be carefully and clinically chosen because higher doses may cause some health risks.

A combined upflow anaerobic sludge bed, aerobic, and anoxic fixed-bed reactor system for removing tetramethylammonium hydroxide and nitrogen from light-emitting diode wastewater

A laboratory study using a combined upflow anaerobic sludge bed (UASB) and aerobic and anoxic fixed-bed reactor system was undertaken to explore its capability for removing tetramethylammonium hydroxide (TMAH) and nitrogen from light-emitting diode wastewater. When the organic loading rate was maintained at 0.26-0.65 kg TMAH m(-3 )d(-1), the UASB reactor removed 70-100% of TMAH through methanogenesis. When the [Formula: see text] -N loading rate was maintained at 0.73-1.4 kg [Formula: see text]-N m(-3 )d(-1), the aerobic reactor oxidized 31-59% of [Formula: see text]-N to [Formula: see text]-N through nitritation. When the nitrogen loading rate was maintained at 0.42-0.75 kg N m(-3 )d(-1), the anoxic reactor removed 27-63% of nitrogen through anammox. The performance data of the combined reactor system agreed well with the stoichiometric relationships of methanogenesis, nitritation, and anammox. The batch studies showed that a higher initial TMAH concentration of up to 2520 mg L(-1) gave a higher methanogenic activity of up to 16 mL CH4 g(-1) VSS d(-1). An increase in the initial TMAH concentration of up to 500 mg L(-1) gradually decreased the activity of ammonia-oxidizing bacteria; whereas an increase in the initial TMAH concentration of up to 47 mg L(-1) imposed a marked inhibiting effect on the activity of anammox bacteria.

Enhanced Anti-Metastatic Activity of Etoposide Using Layered Double Hydroxide Nano Particles

Cell migration and invasion are integral to lung cancer metastasis. In this study, we investigated the combination of traditional chemotherapy and a layered double hydroxide (LDH) carrier as a new strategy for the inhibition of migration and invasion. To investigate the characteristics and possible mechanisms of VP16-LDH [the Mg-Al/LDH containing etoposide (VP16)], we used several experimental techniques, such as transmission electron microscopy (TEM) and fluorescent microscopy. The TEM, X-ray diffraction (XRD) and zeta potential results indicated that VP16 binds well with LDH, with an average size of 70 nm, and the drug delivery system was confirmed to have the desired quality of slow release by the in vitro release test results. Fluorescent images showed that the cellular uptake of VP16-LDH was a caveolae-mediated and energy-dependent process. Moreover, A549 cells treated with VP16-LDH (5 μg/ml, 10 μg/ml) demonstrated significant inhibition of cell migration and invasion compared with the cells treated with free VP16 at the same concentration. The inhibition of AKT, mTOR and STAT3 phosphorylation and p-β-catenin up-regulation in VP16-LDH-treated cells revealed a possible molecular mechanism via the mTOR/AKT and STAT pathways, through which VP16-LDH had a stronger inhibitory effect on migration than the drug alone.

Effect of passive ultrasonic irrigation on diffusion of hydroxyl ion through radicular dentine

OBJECTIVE

This study investigated the effect of passive ultrasonic irrigation (PUI) on diffusion of hydroxyl ions through radicular dentine.

MATERIALS AND METHODS

After chemomechanical preparation of root canals in 60 human teeth, the cementoenamel junction and the apical 3 mm of each root were covered with fast-setting adhesive. Four final irrigation protocols were applied (n = 10): group (G)1: irrigation with EDTA + NaOCl; G2: EDTA + PUI + NaOCl; G3: EDTA+(NaOCl + PUI); G4: (EDTA + PUI) + (NaOCl + PUI). Ten teeth irrigated with distilled water followed by PUI (G5) served as the negative control. After drying, the canals were filled with calcium hydroxide paste (CH), sealed and kept in individual vials containing 10 mL of distilled water with known pH values. At 7, 14, and 21 days, the pH of the water in the vials was measured. The pH values in various groups were analyzed with two-way ANOVA (irrigation protocol and time period as factors) and Holm-Sidak multiple comparison test (α = 0.05).

RESULTS

Changes in pH was not significantly different among groups (P = 0.651) but was significant different among different time periods (P < 0.0001). For all groups, ion diffusion was higher at 14 and 21 days than at 7 days.

CONCLUSIONS

PUI has no effect on diffusion of hydroxyl ions through radicular dentine. When CH is used as temporary filling material, a waiting period of at least 14 days is required to create an alkaline environment within the radicular dentine.

CLINICAL RELEVANCE

The use of PUI during final irrigation phase does not improve the action of CH when it is used as temporary filling material.

Effect of bacterial communities on the formation of cast iron corrosion tubercles in reclaimed water

To understand the role bacterial communities play in corrosion scale development, the morphological and physicochemical characteristics of corrosion scales in raw and disinfected reclaimed water were systematically investigated. Corrosion tubercles were found in raw reclaimed water while thin corrosion layers formed in disinfected reclaimed water. The corrosion tubercles, composed mainly of α-FeOOH, γ-FeOOH, and CaCO3, consisted of an top surface; a shell containing more magnetite than other layers; a core in association with stalks produced by bacteria; and a corroded layer. The thin corrosion layers also had layered structures. These had a smooth top, a dense middle, and a corroded layer. They mostly consisted of the same main components as the tubercles in raw reclaimed water, but with different proportions. The profiles of the dissolved oxygen (DO) concentration, redox potential, and pH in the tubercles were different to those in the corrosion layers, which demonstrated that these parameters changed with a shift in the microbial processes in the tubercles. The bacterial communities in the tubercles were found to be dominated by Proteobacteria (56.7%), Bacteroidetes (10.0%), and Nitrospira (6.9%). The abundance of sequences affiliated to iron-reducing bacteria (IRB, mainly Geothrix) and iron-oxidizing bacteria (mainly Aquabacterium) was relatively high. The layered characteristics of the corrosion layers was due to the blocking of DO transfer by the development of the scales themselves. Bacterial communities could at least promote the layering process and formation of corrosion tubercles. Possible mechanisms might include: (1) bacterial communities mediated the pH and redox potential in the tubercles (which helped to form shell-like and core layers), (2) the metabolism of IRB and magnetic bacteria (Magnetospirillum) might contribute to the presence of Fe3O4 in the shell-like layer, while IRB contributed to green rust in the core layer, and (3) the diversity of the bacterial community resulted in the complex composition of the core layer, and gas producing bacteria (sulfate-reducing bacteria and methanogenic bacteria) played a role in the formation of the porous core layer.

Intrinsic Thermodynamics and Structure Correlation of Benzenesulfonamides with a Pyrimidine Moiety Binding to Carbonic Anhydrases I, II, VII, XII, and XIII

The early stage of drug discovery is often based on selecting the highest affinity lead compound. To this end the structural and energetic characterization of the binding reaction is important. The binding energetics can be resolved into enthalpic and entropic contributions to the binding Gibbs free energy. Most compound binding reactions are coupled to the absorption or release of protons by the protein or the compound. A distinction between the observed and intrinsic parameters of the binding energetics requires the dissection of the protonation/deprotonation processes. Since only the intrinsic parameters can be correlated with molecular structural perturbations associated with complex formation, it is these parameters that are required for rational drug design. Carbonic anhydrase (CA) isoforms are important therapeutic targets to treat a range of disorders including glaucoma, obesity, epilepsy, and cancer. For effective treatment isoform-specific inhibitors are needed. In this work we investigated the binding and protonation energetics of sixteen [(2-pyrimidinylthio)acetyl]benzenesulfonamide CA inhibitors using isothermal titration calorimetry and fluorescent thermal shift assay. The compounds were built by combining four sulfonamide headgroups with four tailgroups yielding 16 compounds. Their intrinsic binding thermodynamics showed the limitations of the functional group energetic additivity approach used in fragment-based drug design, especially at the level of enthalpies and entropies of binding. Combined with high resolution crystal structural data correlations were drawn between the chemical functional groups on selected inhibitors and intrinsic thermodynamic parameters of CA-inhibitor complex formation.

Mini-review: the morphology, mineralogy and microbiology of accumulated iron corrosion products

Despite obvious differences in morphology, substratum chemistry and the electrolyte in which they form, accumulations of iron corrosion products have the following characteristics in common: stratification of iron oxides/hydroxides with a preponderance of α-FeOOH (goethite) and accumulation of metals. Bacteria, particularly iron-oxidizing and sulfate-reducing bacteria have been identified in some accumulations. Both biotic and abiotic mechanisms have been used to rationalize observations for particular sets of environmental data. This review is the first to compare observations and interpretations.

Intrathecal infusion of hydrogen-rich normal saline attenuates neuropathic pain via inhibition of activation of spinal astrocytes and microglia in rats

BACKGROUND

Reactive oxygen and nitrogen species are key molecules that mediate neuropathic pain. Although hydrogen is an established antioxidant, its effect on chronic pain has not been characterized. This study was to investigate the efficacy and mechanisms of hydrogen-rich normal saline induced analgesia.

METHODOLOGY/PRINCIPAL FINDINGS

In a rat model of neuropathic pain induced by L5 spinal nerve ligation (L5 SNL), intrathecal injection of hydrogen-rich normal saline relieved L5 SNL-induced mechanical allodynia and thermal hyperalgesia. Importantly, repeated administration of hydrogen-rich normal saline did not lead to tolerance. Preemptive treatment with hydrogen-rich normal saline prevented development of neuropathic pain behavior. Immunofluorochrome analysis revealed that hydrogen-rich normal saline treatment significantly attenuated L5 SNL-induced increase of 8-hydroxyguanosine immunoreactive cells in the ipsilateral spinal dorsal horn. Western blot analysis of SDS/PAGE-fractionated tyrosine-nitrated proteins showed that L5 SNL led to increased expression of tyrosine-nitrated Mn-containing superoxide dismutase (MnSOD) in the spinal cord, and hydrogen-rich normal saline administration reversed the tyrosine-nitrated MnSOD overexpression. We also showed that the analgesic effect of hydrogen-rich normal saline was associated with decreased activation of astrocytes and microglia, attenuated expression of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the spinal cord.

CONCLUSION/SIGNIFICANCE

Intrathecal injection of hydrogen-rich normal saline produced analgesic effect in neuropathic rat. Hydrogen-rich normal saline-induced analgesia in neuropathic rats is mediated by reducing the activation of spinal astrocytes and microglia, which is induced by overproduction of hydroxyl and peroxynitrite.

Hydroxo-bridged dicopper(II,III) and -(III,III) complexes: models for putative intermediates in oxidation catalysis

A macrocyclic ligand (L(4-)) comprising two pyridine(dicarboxamide) donors was used to target reactive copper species relevant to proposed intermediates in catalytic hydrocarbon oxidations by particulate methane monooxygenase and heterogeneous zeolite systems. Treatment of LH4 with base and Cu(OAc)2·H2O yielded (Me4N)2[L2Cu4(μ4-O)] (1) or (Me4N)[LCu2(μ-OH)] (2), depending on conditions. Complex 2 was found to undergo two reversible 1-electron oxidations via cyclic voltammetry and low-temperature chemical reactions. On the basis of spectroscopy and theory, the oxidation products were identified as novel hydroxo-bridged mixed-valent Cu(II)Cu(III) and symmetric Cu(III)2 species, respectively, that provide the first precedence for such moieties as oxidation catalysis intermediates.

Development of drug delivery systems based on layered hydroxides for nanomedicine

Layered hydroxides (LHs) have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life.

Study of environmental risks incurred by leakage of lithium cells to the food chain in a freshwater ecosystem

Water flea (Daphnia magna) and fish (Carassius auratus) at trophic level were used for comprehensive evaluation of environmental risks incurred by manufactured nanomaterial (nNi(OH)2) as leaked from lithium cells to the food chain in freshwater ecosystem. The 48, 72 and 96 h acute toxicities of water suspensions of nNi(OH)2 to the flea and the fish were tested, using the immobilization and the mortality as toxicological endpoints. The results showed that the water flea was more highly sensitive to nNi(OH)2 than the fish. Then, the fish were exposed to 1.0 mg/L nNi(OH)2 for 6, 12, 24, 36, 48, 60, 72 and 96 h, and the relationship between the concentrations in the water and the fish were described by a bioconcentration factor (BCF). After calculation, lgBCF is 1.61. Reactive oxygen species (ROS) generation was studied after fish were exposed to 1.0 mg/L water suspensions of nNi(OH)2 for 24 h. As proved by electron paramagnetic resonance, nNi(OH)2 may induce the generation of hydroxyl radical in the fish, and nNi(OH)2 as concentrated in the fish may incur redox reaction and produce redox metabolic intermediates. As one of the important toxic mechanisms of nNi(OH)2 to the fish, the oxidative stress mechanism requires further study.

Synergism between polyamines and ROS in the induction of Ca ( 2+) and K (+) fluxes in roots

Stress conditions cause increases in ROS and polyamines levels, which are not merely collateral. There is increasing evidence for the ROS participation in signaling as well as for polyamine protective roles under stress. Polyamines and ROS, respectively, inhibit cation channels and induce novel cation conductance in the plasma membrane. Our new results indicate that polyamines and OH (•) also stimulate Ca ( 2+) pumping across the root plasma membrane. Besides, polyamines potentiate the OH (•) -induced non-selective current and respective passive K (+) and Ca ( 2+) fluxes. In roots this synergism, however, is restricted to the mature zone, whereas in the distal elongation zone only the Ca ( 2+) pump activation is observed. Remodeling the plasma membrane ion conductance by OH (•) and polyamines would impact K (+) homeostasis and Ca ( 2+) signaling under stress.

Zinc ions block H⁺/OH⁻ channels in Chara australis

Chara australis cells exposed to media of pH 10 and above exhibit high conductance, arising from the opening of H⁺/OH⁻ channels in the plasma membrane. This high conductance can be totally inhibited by 1.0 mm ZnCl₂ and restored by 0.5 mm 2-mercaptoethanol (ME). Important for carbon fixation, H⁺/OH⁻ channels play a key role in cell pH banding. Banding was also shown to be abolished by 1.0 mm ZnCl₂ and restored in some cells by ME. The proton pump is also involved in banding, but was little affected by ZnCl₂ over the periods needed for the inhibition of H⁺/OH⁻ channels. Previously, we postulated that H⁺/OH⁻ channels open transiently at the onset of saline stress in salt-sensitive C. australis, causing membrane potential difference (PD) noise; and remain open in latter stages of saline stress, contributing to cell deterioration. ZnCl₂ totally inhibited the saline noise and the upwardly concave I/V characteristics associated with the putative H⁺/OH⁻ currents. Again, ME reversed both these effects. We discuss the mode of action of zinc ions and ME with reference to animal voltage-gated H⁺ channels and water channels.

Tolerance and bioaccumulation of copper by the entomopathogen Beauveria bassiana (Bals.-Criv.) Vuill. exposed to various copper-based fungicides

This work evaluates for the first time the relationships between copper-tolerance, -solubilization and -bioaccumulation in the entomopathogen Beauveria bassiana exposed to Bordeaux mixture, copper oxychloride or copper hydroxide. Bordeaux mixture was highly detrimental to fungus, by inhibiting the growth totally at the recommended dose (RD) and 2×RD. Copper hydroxide and copper oxychloride were found to be less toxic, reducing fungus growth, sporulation and conidial germination in an average of 29  %, 30 % and 58 %, respectively. These two copper forms were the easiest to solubilize, to precipitate and the most accumulated by B. bassiana, suggesting the involvement of all these processes on fungus copper-tolerance.

Biological treatment of TMAH (tetra-methyl ammonium hydroxide) in a full-scale TFT-LCD wastewater treatment plant

This study evaluated biological treatment of TMAH in a full-scale methanogenic up-flow anaerobic sludge blanket (UASB) followed by an aerobic bioreactor. In general, the UASB was able to perform a satisfactory TMAH degradation efficiency, but the effluent COD of the aerobic bioreactor seemed to increase with an increased TMAH in the influent wastewater. The batch test results confirmed that the UASB sludge under methanogenic conditions would be favored over the aerobic ones for TMAH treatment due to its superb ability of handling high strength of TMAH-containing wastewaters. Based on batch experiments, inhibitory chemicals present in TFT-LCD wastewater like surfactants and sulfate should be avoided to secure a stable methanogenic TMAH degradation. Finally, molecular monitoring of Methanomethylovorans hollandica and Methanosarcina mazei in the full-scale plant, the dominant methanogens in the UASB responsible for TMAH degradation, may be beneficial for a stable TMAH treatment performance.

A 5'-terminal phosphate is required for stable ternary complex formation and translation of leaderless mRNA in Escherichia coli

The bacteriophage λ's cI mRNA was utilized to examine the importance of the 5'-terminal phosphate on expression of leadered and leaderless mRNA in Escherichia coli. A hammerhead ribozyme was used to produce leadered and leaderless mRNAs, in vivo and in vitro, that contain a 5'-hydroxyl. Although these mRNAs may not occur naturally in the bacterial cell, they allow for the study of the importance of the 5'-phosphorylation state in ribosome binding and translation of leadered and leaderless mRNAs. Analyses with mRNAs containing either a 5'-phosphate or a 5'-hydroxyl indicate that leaderless cI mRNA requires a 5'-phosphate for stable ribosome binding in vitro as well as expression in vivo. Ribosome-binding assays show that 30S subunits and 70S ribosomes do not bind as strongly to 5'-hydroxyl as they do to 5'-phosphate containing leaderless mRNA and the tRNA-dependent ternary complex is less stable. Additionally, filter-binding assays revealed that the 70S ternary complex formed with a leaderless mRNA containing a 5'-hydroxyl has a dissociation rate (k(off)) that is 4.5-fold higher compared with the complex formed with a 5'-phosphate leaderless mRNA. Fusion to a lacZ reporter gene revealed that leaderless cI mRNA expression with a 5'-hydroxyl was >100-fold lower than the equivalent mRNA with a 5'-phosphate. These data indicate that a 5'-phosphate is an important feature of leaderless mRNA for stable ribosome binding and expression.

Determination of the antioxidants' ability to scavenge free radicals using biosensors

Free radicals are highly reactive molecules generated during cellular metabolism. However, their overproduction results in oxidative stress, a deleterious process that can damage cell structures, including lipids and membranes, proteins and DNA. Antioxidants respond to this problem, scavenging free radicals. This chapter critically reviews the electrochemical biosensors developed for the evaluation of the antioxidant capacity of specific compounds. Due to the ability of these devices to perform simple, fast and reliable analysis, they are promising biotools for the assessment ofantioxidant properties.

Potent antioxidant and genoprotective effects of boeravinone G, a rotenoid isolated from Boerhaavia diffusa

BACKGROUND AND AIMS

Free radicals are implicated in the aetiology of some gastrointestinal disorders such as gastric ulcer, colorectal cancer and inflammatory bowel disease. In the present study we investigated the antioxidant and genoprotective activity of some rotenoids (i.e. boeravinones) isolated from the roots of Boerhaavia diffusa, a plant used in the Ayurvedic medicine for the treatment of diseases affecting the gastrointestinal tract.

METHODS/PRINCIPAL FINDINGS

Antioxidant activity has been evaluated using both chemical (Electron Spin Resonance spectroscopy, ESR) and Caco-2 cells-based (TBARS and ROS) assays. DNA damage was evaluated by Comet assay, while pERK(1/2) and phospho-NF-kB p65 levels were estimated by western blot. Boeravinones G, D and H significantly reduced the signal intensity of ESR induced by hydroxyl radicals, suggesting a scavenging activity. Among rotenoids tested, boeravinone G exerted the most potent effect. Boeravinone G inhibited both TBARS and ROS formation induced by Fenton's reagent, increased SOD activity and reduced H(2)O(2)-induced DNA damage. Finally, boeravinone G reduced the levels of pERK(1) and phospho-NF-kB p65 (but not of pERK(2)) increased by Fenton's reagent.

CONCLUSIONS

It is concluded that boeravinone G exhibits an extraordinary potent antioxidant activity (significant effect in the nanomolar range). The MAP kinase and NF-kB pathways seem to be involved in the antioxidant effect of boeravinone G. Boeravinone G might be considered as lead compound for the development of drugs potentially useful against those pathologies whose aetiology is related to ROS-mediated injuries.

The hydroxyl functional group of N-(4-hydroxyphenyl)retinamide mediates cellular uptake and cytotoxicity in premalignant and malignant human epithelial cells

In a previous study, we demonstrated that the anticancer synthetic retinoid N-(4-hydroxyphenyl)retinamide (4HPR) redox cycles at the mitochondrial enzyme dihydroorotate dehydrogenase to trigger anomalous reactive oxygen species (ROS) production and attendant apoptosis in transformed human epithelial cells. Furthermore, we speculated that the hydroxyl functional group of 4HPR was required for this pro-oxidant property. In this study, we investigated the role of the hydroxyl functional group in the in vitro cytotoxicity of 4HPR. Using 4HPR, its primary in vivo metabolite N-(4-methoxyphenyl)retinamide (4MPR), and the synthetic derivative N-(4-trifluoromethylphenyl)retinamide (4TPR), we examined the pro-oxidant and apoptotic effects, as well as the cellular uptake, of these three N-(4-substituted-phenyl)retinamides in premalignant and malignant human skin, prostate, and breast epithelial cells. Compared to 4HPR, both 4MPR and 4TPR were ineffective in promoting conspicuous cellular ROS production, mitochondrial disruption, or DNA fragmentation in these transformed cells. Interestingly, both 4MPR and 4TPR were not particularly cell permeative relative to 4HPR in skin or breast epithelial cells, which implied an additional role for the hydroxyl functional group in the cellular uptake of 4HPR. Moreover, the short-term uptake of 4HPR was directly proportional to cell size, but this characteristic, in obvious contrast to cellular bioenergetic status and/or dihydroorotate dehydrogenase expression, was not fundamentally influential in the overall sensitivity to the promotion of cellular ROS production and apoptosis induction by this agent. Together, these results strongly implicate the hydroxyl functional group in the cytotoxic effects of 4HPR.

Interconversion of hydroxylated and methoxylated polybrominated diphenyl ethers in Japanese medaka

Polybrominated diphenyl ethers (PBDEs), hydroxylated (OH) and methoxylated (MeO), have been widely detected in aquatic environments. However, relationships among these structurally related compounds in exposed organisms are unclear. To elucidate biotransformation relationships among BDE-47, 6-OH-BDE-47, and 6-MeO-BDE-47, dietary accumulation, maternal transfer, and tissue distribution of these compounds and their transformation products were investigated in sexually mature Japanese medaka (Oryzias latipes). In addition, transformation of each compound was determined in vitro using liver microsomes of medaka. OH-PBDEs and MeO-PBDEs were not detected in fish exposed to BDE-47. However, significant concentrations of 6-OH-BDE-47 were detected in medaka or microsomes exposed to 6-MeO-BDE-47. Significant concentrations of 6-MeO-BDE-47 were also measured in fish exposed to 6-OH-BDE-47, but 6-MeO-BDE-47 was not detected in microsomes exposed to 6-OH-BDE-47. Similar patterns of transformation products were observed in medaka eggs from adult fish during exposure. This study presents direct in vivo evidence of biotransformation of 6-MeO-BDE-47 to 6-OH-BDE-47. In addition, this is the first study to demonstrate biotransformation of 6-OH-BDE-47 to 6-MeO-BDE-47. Demethylation of 6-MeO-BDE-47 was the primary transformation pathway leading to formation of 6-OH-BDE-47 in medaka, while the previously hypothesized formation of OH-PBDEs from synthetic BDE-47 did not occur. Biotransformation products formed in adult female medaka were transferred to eggs.

Kinetics of transesterification of palm oil and dimethyl carbonate for biodiesel production at the catalysis of heterogeneous base catalyst

The transesterification of palm oil with dimethyl carbonate (DMC) for preparing biodiesel has been studied in solvent-free system at the catalysis of potassium hydroxide (KOH) as heterogeneous catalyst. Fatty acid methyl esters (FAMEs) were analyzed by GC with internal standard method. The effects of reaction conditions (molar ratio of DMC and palm oil, catalyst amount and time) on FAMEs yield were investigated. The highest FAMEs yield could reach 96.2% at refluxing temperature for 8h with molar ratio of DMC and oil 9:1 and 8.5% KOH (based on oil weight). Kinetics of the KOH-catalyzed transesterification of palm oil and DMC was researched over a temperature range of 65-75 degrees C. A pseudo first-order model was proposed. The activation energy (E(a)) was 79.1 kJ mo1(-1) and the pre-exponential factor (k(o)) was 1.26 x 10(9) min(-1) from Arrhenius equation. Further, a plausible reaction mechanism for the catalytic process with DMC as acyl acceptor was proposed.

In vitro and in vivo behavior of ketoprofen intercalated into layered double hydroxides

Ketoprofen (Ket) was intercalated into layered double hydroxides (ZnAlLDH and MgAlLDH) using the ionic exchange method. The drug intercalation was confirmed by X-ray diffraction (XRD) and FTIR spectroscopy. Ket release from the inorganic matrix was studied at pH 7.4 in continuous regime with a flow rate of 0.5 and respectively 1.0 ml/min. The kinetical data were interpreted using the Ritger and Peppas model. The data prove that the release kinetics and mechanism depend on the eluent flow rate. Quantification of gastric tolerance shows that the ulcerogenic effect of the intercalated drug is lower than the one of the raw Ket. The antinociceptive effect of both formulations was studied by the hot-plate method performed on mice. The MgAlLDH_Ket formulation shows a tendency towards a stronger antinociceptive effect than its ZnAlLDH_Ket counterpart during the 210 min recorded period.

Analysis of four connexin26 mutant gap junctions and hemichannels reveals variations in hexamer stability

Connexin26 is a ubiquitous gap junction protein that serves critical homeostatic functions. Four single-site mutations found in the transmembrane helices (M1-M4) cause different types of dysfunctional channels: 1), Cx26T135A in M3 produces a closed channel; 2), Cx26M34A in M1 severely decreases channel activity; 3), Cx26P87L in M2 has been implicated in defective channel gating; and 4), Cx26V84L in M2, a nonsyndromic deafness mutant, retains normal dye coupling and electrophysiological properties but is deficient in IP(3) transfer. These mutations do not affect Cx26 trafficking in mammalian cells, and make normal-appearing channels in baculovirus-infected Sf9 membranes when imaged by negative stain electron microscopy. Upon dodecylmaltoside solubilization of the membrane fraction, Cx26M34A and Cx26V84L are stable as hexamers or dodecamers, but Cx26T135A and Cx26P87L oligomers are not. This instability is also found in Cx26T135A and Cx26P87L hemichannels isolated from mammalian cells. In this work, coexpression of both wild-type Cx26 and Cx26P87L in Sf9 cells rescued P87L hexamer stability. Similarly, in paired Xenopus oocytes, coexpression with wild-type restored function. In contrast, the stability of Cx26T135A hemichannels could not be rescued by coexpression with WT. Thus, T135 and P87 residues are in positions that are important for oligomer stability and can affect gap junction gating.

Toxicity and biotransformation of uncoated and coated nickel hydroxide nanoparticles on mesquite plants

Nanomaterials are of particular interest in environmental chemistry due to their unknown toxicity to living organisms. Reports indicate that nanoparticles (NPs) affect seed germination, but the uptake and biotransformation of metal nanoparticles is not well understood. The present study investigated the toxicity and biotransformation of Ni(OH)2 NPs by mesquite plants (Prosopis sp.). Three sets of plants were treated for four weeks with 0.01, 0.05, or 0.10 g of either uncoated or sodium citrate coated NPs before and after synthesis. Nickel concentrations in plants were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and the form and oxidation state of Ni was determined using X-ray absorption spectroscopy (XAS). Results showed that uncoated NPs had an average size of 8.7 nm, whereas coated NPs before and after synthesis had an average of 2.5 and 0.9 nm, respectively. The ICP-OES results showed that plants treated with 0.10 g of uncoated and coated NPs before and after synthesis had 803, 764, and 400 mg Ni kg dry weight, in the leaves, respectively. The XAS analyses showed Ni NPs in roots and shoots of plants treated with uncoated NPs, whereas leaves showed a Ni(II)-organic acid type complex. However, plants treated with coated NPs before or after synthesis showed Ni NPs only in roots and a Ni(II)-organic acid complex in shoots and leaves. Results also showed that none of the treatments reduced plant size or chlorophyll production. To the authors' knowledge, this is the first time that the biotransformation of nanoparticles by a plant system is reported.

Release of SF3 from the intron branchpoint activates the first step of pre-mRNA splicing

Eukaryotic pre-mRNA splicing is a complex process requiring the precise timing and action of >100 trans-acting factors. It has been known for some time that the two steps of splicing chemistry require three DEAH-box RNA helicase-like proteins; however, their mechanism of action at these steps has remained elusive. Spliceosomes arrested in vivo at the three helicase checkpoints were purified, and first step-arrested spliceosomes were functionally characterized. We show that the first step of splicing requires a novel ATP-independent conformational change. Prp2p then catalyzes an ATP-dependent rearrangement displacing the SF3a and SF3b complexes from the branchpoint within the spliceosome. We propose a model in which SF3 prevents premature nucleophilic attack of the chemically reactive hydroxyl of the branchpoint adenosine prior to the first transesterification. When the spliceosome attains the proper conformation and upon the function of Prp2p, SF3 is displaced from the branchpoint allowing first step chemistry to occur.

Ascorbate and Cu(II)-induced oxidative degradation of high-molar-mass hyaluronan. Pro- and antioxidative effects of some thiols

OBJECTIVE

This study presents the results of antioxidative and pro-oxidative efficacy of cysteamine and D-penicillamine (D-pen) in comparison to L-glutathione (L-GSH) on high-molar-mass hyaluronan (HA) degradation by cupric ions plus ascorbic acid.

METHODS

The substance tested was applied in the degradative system cupric ions plus ascorbate: (i) before the reaction onset or also (ii) 1 h after the reaction started. The results obtained were compared with that one recorded by using the degradative system in the absence of the substance tested. To monitor HA degradation kinetics, rotational viscometry was applied. Moreover, the standard ABTS and DPPH assays were used.

RESULTS

By using the method of rotational viscometry, D-pen showed dual effect: initial inhibitory effect on •OH radicals was changed to a pro-oxidative one in the dose and time dependent manner. Both L-GSH and cysteamine were recorded to be more effective scavengers of •OH radicals than D-pen. Cysteamine demonstrated to be an excellent scavenger also of alkoxyl- and peroxyl- type radicals. Based on IC50 values, gained by ABTS assay, it is evident that D-pen showed higher radical scavenging capacity compared to cysteamine. Similar results were observed also in DPPH assay, although in this assay less effective radical scavenging capacities of both substances tested were recorded.

CONCLUSIONS

On the basis of the results obtained, it can be stated that D-pen can produce hydrogen peroxide or •OH radicals and can inhibit the production of these oxidants. Our results showed that both L-GSH and cysteamine are similarly effective in inhibiting of HA degradation. Moreover, cysteamine demonstrated to be a significant inhibitor of alkoxyl- and peroxyl- type radicals generated from C-type macroradical of HA.

Complement activation by polymers carrying hydroxyl groups

Hydrogels of polymers carrying surface hydroxyl groups strongly activate the complement system through the alternative pathway, although it has also been reported that solutions of polymers do not. To address these curious, inconsistent results, we examined the effect of polymer states, either immobilized on a surface or soluble in serum, on the complement activation using a surface plasmon resonance apparatus and enzyme-linked immunosorbent assay. We clearly showed that dextran- and poly(vinyl alcohol)-immobilized surfaces strongly activated the complement system but that soluble polymers could not, even when the amounts of the soluble polymers added to serum were 4-2000 times higher than those on the polymer-immobilized surfaces.

Large-scale production of poly(3-hydroxyoctanoic acid) by Pseudomonas putida GPo1 and a simplified downstream process

The suitability of Pseudomonas putida GPo1 for large-scale cultivation and production of poly(3-hydroxyoctanoate) (PHO) was investigated in this study. Three fed-batch cultivations of P. putida GPo1 at the 350- or 400-liter scale in a bioreactor with a capacity of 650 liters were done in mineral salts medium containing initially 20 mM sodium octanoate as the carbon source. The feeding solution included ammonium octanoate, which was fed at a relatively low concentration to promote PHO accumulation under nitrogen-limited conditions. During cultivation, the pH was regulated by addition of NaOH, NH(4)OH, or octanoic acid, which was used as an additional carbon source. Partial O(2) pressure (pO(2)) was adjusted to 20 to 40% by controlling the airflow and stirrer speed. Under the optimized conditions, P. putida GPo1 was able to grow to cell densities as high as 18, 37, and 53 g cells (dry mass) (CDM) per liter containing 49, 55, and 60% (wt/wt) of PHO, respectively. The resulting 40 kg CDM from these three cultivations was used directly for extraction of PHO. Three different methods of extraction of PHO were applied. From these, only acetone extraction showed better performance and resulted in 94% recovery of the PHO contents of cells. A novel mixture of precipitation solvents composed of 70% (vol/vol) methanol and 70% (vol/vol) ethanol was identified in this study. The ratio of PHO concentrate to the mixture was 0.2:1 (vol/vol) and allowed complete precipitation of PHO as white flakes. However, at a ratio of 1:1 (vol/vol) of the solvent mixture to PHO concentrate, a highly purified PHO was obtained. Precipitation yielded a dough-like polymeric material which was cast into thin layers and then shredded into small strips to allow evaporation of the remaining solvents. Gas chromatographic analysis revealed a purity of about 99% +/- 0.2% (wt/wt) of the polymer, which consisted mainly of 3-hydroxyoctanoic acid (96 mol%).

Quantitative structure-property relationship modelling of the degradability rate constant of alkenes by OH radicals in atmosphere

In this work, the degradability rate constants of 98 alkenes by OH radicals were predicted from theoretically derived descriptors, which were calculated from the molecular structure alone by applying a quantitative structure-property relationship (QSPR) approach. For the selection of the most relevant descriptors, stepwise multiple linear regression (MLR) and genetic algorithms (GAs) were used. Then some linear and nonlinear techniques were used for the investigation of the relation between selected molecular descriptors and the OH radical degradability rate constant. These methods were MLR, artificial neural networks (ANNs) and support vector machines (SVMs). According to the variable selection method and feature mapping techniques, six QSPR models were constructed which were: stepwise-MLR-MLR, stepwise-MLR-ANN, stepwise-MLR-SVM, GA-MLR, GA-ANN, and GA-SVM. The credibility of these models was evaluated by a leave-24-out cross-validation test. The statistical results are Q(2) = 0.86, SPRESS = 0.16 for GA-ANN, Q(2) = 0.69, SPRESS = 0.20 for GA-SVM, and Q(2) = 0.83, SPRESS = 0.18 for GA-MLR model. Based on these values and other statistical parameters obtained in this work, it was concluded that the GA-ANN model outperformed the other models.

Oxidative response of phagocytes to parasite invasion

Phagocytes destroy intracellular pathogens and extracellular targets in part by the production of toxic oxygen metabolites--namely, superoxide, hydrogen peroxide, hydroxyl radicals and possibly singlet molecular oxygen. The toxicity of hydrogen peroxide is increased greatly by peroxidase and a halide. A peroxidase that can be used for this purpose is present in neutrophils and monocytes (myeloperoxidase), but is lost when the monocyte matures into a macrophage; a different peroxidase is present in eosinophils. The latter enzyme, because of its strong positive charge, binds to the surface of parasites; any phagocyte in the region, when appropriately stimulated, may provide the hydrogen peroxide required for completion of the peroxidase system. Further, peroxidase-coated organisms are more readily killed when ingested by macrophages than are uncoated organisms. Oxygen-dependent toxicity requires the production of toxic oxygen products by phagocytes in amounts sufficient to overcome the protective capacity of endogenous scavengers in the parasite. The latter include catalase and glutathione peroxidase, which degrade hydrogen peroxide, and superoxide dismutase which dissipates superoxide. The host defence against parasites appears to depend in part on this balance between toxic oxygen metabolites and scavengers.

Carbon monoxide alleviates cadmium-induced oxidative damage by modulating glutathione metabolism in the roots of Medicago sativa

Using pharmacological and biochemical approaches, the role of cadmium (Cd)-induced carbon monoxide (CO) release and the relationship between CO and oxidative stress conferred by Cd exposure in the root tissues of alfalfa (Medicago sativa) plants were investigated. Cd treatments showed a dose-dependent enhancement in lipid peroxidation. Both 100 and 200 microm CdCl(2 )treatments caused the increase of CO release, which is consistent with the changes in the activity of the CO synthetic enzyme heme oxygenase (HO) and its HO-1 transcript. A 100 microm CdCl(2) exposure enhanced the formation of nonprotein thiols (NPT), and reduced glutathione (GSH) to oxidized glutathione (GSSG), which was potentiated by the pretreatment of CO scavenger hemoglobin (Hb). Plants pretreated for 6 h with 50% CO-saturated aqueous solution, which induced the rapid endogenous CO release followed by a gradual decrease when subsequently exposed to 100 microm CdCl(2) for 72 h, effectively decreased oxidative damage. Meanwhile, CO pretreatment modulated several enzymes responsible for GSH metabolism, thus resulting in the partial restoration of GSH : GSSG ratio, which was significantly blocked by Hb. These results are suggestive of a role for CO release as a signal element for the alleviation of Cd-induced oxidative damage by modulating glutathione metabolism.

Integrated microfluidic cell culture and lysis on a chip

We present an integrated microfluidic cell culture and lysis platform for automated cell analysis that improves on systems which require multiple reagents and manual procedures. Through the combination of previous technologies developed in our lab (namely, on-chip cell culture and electrochemical cell lysis) we have designed, fabricated, and characterized an integrated microfluidic platform capable of culturing HeLa, MCF-7, Jurkat, and CHO-K1 cells for up to five days and subsequently lysing the cells without the need to add lysing reagents. On-demand lysis was accomplished by local hydroxide ion generation within microfluidic chambers, releasing both proteinacious (GFP) and genetic (Hoescht-stained DNA) material. Sample proteins exposed to the electrochemical lysis conditions were immunodetectable (p53) and their enzymatic activity (HRP) was investigated.

Controlled formation of magnetite crystal by partial oxidation of ferrous hydroxide in the presence of recombinant magnetotactic bacterial protein Mms6

Mms6 is a small acidic protein that is tightly associated with bacterial magnetite in Magnetospirillum magneticum AMB-1. This protein has previously shown iron binding activity, allowing it to generate uniform magnetic crystals by co-precipitation of ferrous and ferric ions. Here, magnetite crystals were formed by the partial oxidation of ferrous hydroxide in the presence and absence of Mms6. The crystals synthesised were systematically characterised according to their sizes and morphologies using high-resolution transmission electron microscopy. Mms6-mediated synthesis of magnetite by this methods produced crystals of a uniform size and narrow size distribution with a cubo-octahedral morphology, similar to bacterial magnetite observed in M. magneticum AMB-1. The crystals formed in the absence of Mms6 were octahedral, larger with an increased size distribution. Protein quantification analysis of Mms6 in the synthesised particles indicated tight association of this protein onto the crystal. Furthermore, high affinities to iron ions and a highly charged electrostatic quality suggest that the protein acts as a template for the nucleus formation and/or acts as a growth regulator by recognising crystal faces. The method introduced in this study presents an alternative route for controlling the size and shape of magnetite crystals without the use of organic solvent and high temperatures.