Disruption of Membrane Integrity as a Molecular Initiating Event Determines the Toxicity of Polyhexamethylene Guanidine Phosphate Depending on the Routes of Exposure

Polyhexamethylene guanidine phosphate (PHMG-P), a cationic biocide, is widely used in household products due to its strong bactericidal activity and low toxicity. However, it causes fatal lung damage when inhaled. In this study, we investigated why PHMG-P causes fatal lung injury when inhaled, and demonstrated that the disruption of membrane integrity through ionic interaction—a molecular initiating event of PHMG-P—determines toxicity. Mice were injected intravenously with 0.9 or 7.2 mg/kg PHMG-P (IV group), or instilled intratracheally with 0.9 mg/kg PHMG-P (ITI group); they were euthanatized at 4 h and on days 1 and 7 after treatment. Increased total BAL cell count and proinflammatory cytokine production, along with fibrotic changes in the lungs, were detected in the ITI group only. Levels of hepatic enzymes and hepatic serum amyloid A mRNA expression were markedly upregulated in the 7.2 mg/kg IV and ITI groups at 4 h or day 1 after treatment, but returned to baseline. No pathological findings were detected in the heart, liver, or kidneys. To simulate the IV injection, A549, THP-1, and HepG2 cells were treated with PHMG-P in cell culture media supplemented with different serum concentrations. Increased serum concentration was associated with an increase in cell viability. These results support the idea that direct contact between PHMG-P and cell membranes is necessary for PHMG-induced toxicity.     

Effect of hydrodymamic force and prolonged oxygen exposure on the performance of anodic biofilm in microbial electrolysis cells

In this work, the significance of Reynolds number (N_Re) in evaluating the performance of hydrogen production in MECs was demonstrated. Experiments performed with the same anode under the same operating conditions (applied potential, pH, stirring speed and substrate concentration) showed different performances when operated with different stirrers. An average increase of 30% in hydrogen production was obtained by increasing the diameter of the stirring bar from 1.2 cm to 2.8 cm. This increased the N_Re from ≈900 to ≈4900. The anodic bacteria communities on MEC's anodes were also shown to be unaffected when exposed to oxygen for a prolonged period of time outside the reactor by storing them in buffer solution. This however was not enough to get rid of methanogenic bacteria which were still active on the electrodes after exposing them to oxygen in the air for 24 h and in buffer solution for 5 days.     

Low‐profile mechanisms in a PVAc/polyester blend

The different steps associated with the curing of a PVAc/polyester blend are identified and correlated to the mechanism of shrinkage control in the presence of a low‐profile additive (LPA). Poly(vinyl acetate) (PVAc) is used as a LPA and is shown to induce a phase separation upon curing that leads to an interconnected globule morphology. This morphology strongly modifies the rheokinetics of the blend compared to that of the neat polyester resin. In particular, the presence of PVAc delays the cure kinetics and the gel time. A comparison between these delays, called shift times, demonstrates an increase in the gel conversion of polyester in the presence of PVAc. This, coupled to the thermal expansion of PVAc at the early stages of curing, contributes to the low‐profile effect. Microvoids in the LPA‐rich phase, which are believed to play a key role in the mechanism of shrinkage control, are efficient at the later stages of curing and during cooling and complete the low‐profile effect. However, it is also shown that the formation of microvoids may indirectly induce macroscopic voids that could be at the origin of pinholes at the surface of the parts molded with this material. POLYM. ENG. SCI. 46:303–313, 2006. © 2006 Society of Plastics Engineers     

Cobalt oxide polymorph growth on electrostatic self-assembled nanoparticle arrays for dually tunable nano-textures

We report on a method for surface nano-texturing on a plastic substrate. Nano-objects with a silica nanoparticle core and a textured cobalt oxide crown are created with selectable density on the plastic substrate. The resulting dual morphology is easily tuned over large areas, either by changing the parameters directing nanoparticle deposition through electrostatic self-arrangement for nano-object density control, or the parameter directing cobalt oxide deposition for shape control. The entire process takes place at room temperature, with no chemicals harmful to the plastic substrate. The ready modulation of the dual morphology is used to control the wettability properties of the plastic film, which is covered by nano-objects.     

Comparative studies on major nutritional components of black waxy rice with giant embryos and its rice bran

The concentration of nutrients in brown rice is mainly associated with embryo size. Various beneficial components have been purified from rice bran. Recently developed black waxy rice with a giant embryo (‘Milyang 263’, BGE), which is the ge ^t mutant of the GE gene, was selected and analyzed to produce high quality nutritional components. γ-Aminobutyric acid (GABA) content in BGE rice bran, one of the most important nutritional compounds in rice, showed a 10.6-fold increase (2.66±0.48 mg/g) compared to that of BGE brown rice (0.25±0.01 mg/g). In addition, brown rice and BGE rice bran showed enriched amylopectin (94.5±0.5 and 97.0±0.0%) and bioactive anthocyanin [Cy-3-G: 75.15±4.18 (brown rice), 82.97±0.81 (rice bran) and Pn-3-G: 1.52±0.50 (brown rice), 4.33±0.20 (rice bran); mg/100 g] contents. These results suggest that BGE rice bran can be used as an excellent raw material to efficiently produce high quality essential amino acids, cyanidin-3 glycoside-enriched anthocyanins, and GABA.     

Study of hydrogen production in light assisted microbial electrolysis cell operated with dye sensitized solar cell

Hydrogen production with light as an additional energy source in a microbial electrolysis cell (MEC) is described. A ruthenium-dye (N719) sensitized solar cell with an open circuit potential (V_oc) of 602 mV was connected to the MEC. Hydrogen production was carried out by irradiating the DSSC connected across the MEC with a light intensity of 40 mW/cm² and also with natural sunlight. The DSSC was stable during various batch experiments. The acetate conversion efficiency and the coulombic efficiency based on the average of first two batches were 30.5 ± 2.5% and 40 ± 2% respectively. The cathodic recovery efficiency ranged from 72% to 86% during repeated batch experiments with an average of 78 ± 2.5%.     

Inhibitory Effect of a Glutamine Antagonist on Proliferation and Migration of VSMCs via Simultaneous Attenuation of Glycolysis and Oxidative Phosphorylation

Excessive proliferation and migration of vascular smooth muscle cells (VSMCs) contribute to the development of atherosclerosis and restenosis. Glycolysis and glutaminolysis are increased in rapidly proliferating VSMCs to support their increased energy requirements and biomass production. Thus, it is essential to develop new pharmacological tools that regulate metabolic reprogramming in VSMCs for treatment of atherosclerosis. The effects of 6-diazo-5-oxo-L-norleucine (DON), a glutamine antagonist, have been broadly investigated in highly proliferative cells; however, it is unclear whether DON inhibits proliferation of VSMCs and neointima formation. Here, we investigated the effects of DON on neointima formation in vivo as well as proliferation and migration of VSMCs in vitro. DON simultaneously inhibited FBS- or PDGF-stimulated glycolysis and glutaminolysis as well as mammalian target of rapamycin complex I activity in growth factor-stimulated VSMCs, and thereby suppressed their proliferation and migration. Furthermore, a DON-derived prodrug, named JHU-083, significantly attenuated carotid artery ligation-induced neointima formation in mice. Our results suggest that treatment with a glutamine antagonist is a promising approach to prevent progression of atherosclerosis and restenosis.     

ITO-free inverted polymer solar cells using a GZO cathode modified by ZnO

A gallium-doped ZnO (GZO) layer was investigated and compared with a conventional indium-tin-oxide (ITO) layer for use as a cathode in an inverted polymer solar cell based on poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C₆₁ butyric acid methyl ester (PCBM) bulk heterojunctions (BHJ). By modifying the GZO cathode with a ZnO thin layer, a high power conversion efficiency (3.4%) comparable to that of an inverted solar cell employing the same P3HT:PCBM BHJ photoactive layer with a conventional ITO/ZnO cathode was achieved. This result indicates that GZO is a transparent electrode material that can potentially be used to replace high-cost ITO.