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Acidification of the resorption pits, which is essential for dissolving bone, is produced by secretion of protons through vacuolar H(+)-ATPases in the plasma membrane of bone-resorbing cells, osteoclasts. Consequently, osteoclasts face highly acidic extracellular environments, where the pH gradient across the plasma membrane could generate a force driving protons into the cells. Proton influx mechanisms during the acid exposure are largely unknown, however. In this study, we investigated extracellular-acid-inducible proton influx currents in osteoclast-like cells derived from a macrophage cell line (RAW264). Decreasing extracellular pH to

Key points • Voltage-gated H+ channels help to compensate for the pH and voltage disturbances generated by production of reactive oxygen species. • In this study, we investigated how changes in the intracellular pH levels control H+ channel activity in macrophage-lineage cells, osteoclasts and microglia. • An increase in intracellular pH decreased the numbers of H+ channels available at the plasma membrane through facilitation of dynamin-dependent endocytic internalization. • This inhibitory regulation mechanism for H+ channels is novel. • The results help us to understand better the significance of the intracellular pH levels in membrane dynamics and H+ channel availability, which, in turn, may modulate natural immunity. Abstract Voltage-gated proton channels (H+ channels) are highly proton-selective transmembrane pathways. Although the primary determinants for activation are the pH and voltage gradients across the membrane, the current amplitudes fluctuate often when these gradients are constant. The aim of this study was to investigate the role of the intracellular pH (pHi) in regulating the availability of H+ channels in osteoclasts and microglia. In whole-cell clamp recordings, the pHi was elevated after exposure to NH4Cl and returned to the control level after washout. However, the H+ channel conductance did not recover fully when the exposure was prolonged (>5 min). Similar results were observed in osteoclasts and microglia, but not in COS7 cells expressing a murine H+ channel gene (mVSOP). As other electrophysiological properties, like the gating kinetics and voltage dependence for activation, were unchanged, the decreases in the H+ channel conductance were probably due to the decreases in H+ channels available at the plasma membrane. The decreases in the H+ channel conductances were accompanied by reductions in the cell capacitance. Exposure to NH4Cl increased the uptake of the endocytosis marker FM1-43, substantiating the idea that pHi increases facilitated endocytosis. In osteoclasts, whose plasma membrane expresses V-ATPases and H+ channels, pHi increases by these H+-transferring molecules in part facilitated endocytosis. The endocytosis and decreases in the H+ channel conductance were reduced by dynasore, a dynamin blocker. These results suggest that pHi increases in osteoclasts and microglia decrease the numbers of H+ channels available at the plasma membrane through facilitation of dynamin-dependent endocytosis.

Photocycloaddition of cyclohexenones with vinyl acetates or vinyl ethers, and the Paterno–Buchi reaction were carried out using photomicroreactors in combination with compact light sources such as low-power black lights and UV LEDs. The observed high efficiency holds promise as an energy-saving protocol for photoinduced [2 + 2] cycloaddition reactions.

application/pdf, Article, Chemical Engineering Journal. 2011, 167 (2-3), p.567-571

The photobromination of C-H bonds by using molecular bromine was reinvestigated under microfluidic conditions. The continuous-flow method suppressed the production of dibrominated compounds and effectively produced the desired monobrominated products with high selectivity. Rapid bromination of benzylic substrates containing a photoaffinity azide group was achieved without any decomposition.

The perceptional change of fragrance of essential oils is described in relation to type of work, i.e. mental work, physical work and hearing environmental (natural) sounds. The essential oils examined in this study were ylang ylang, orange, geranium, cypress, bergamot, spearmint and juniper. In evaluating change in perception of a given aroma, a sensory test was employed in which the perception of fragrance was assessed by 13 contrasting pairs of adjectives. Scores were recorded after inhaling a fragrance before and after each type of work, and the statistical significance of the change of score for 13 impression descriptors was examined by Student's t-test for each type of work. It was confirmed that inhalation of essential oil caused a different subjective perception of fragrance depending on the type of work. For example, inhalation of cypress after physical work produced a much more favorable impression than before work, in contrast to orange, which produced an unfavorable impression after physical work when compared with that before work. For mental work, inhalation of juniper seemed to create a favorable impression after work, whereas geranium and orange both produced an unfavorable impression then. From these studies, together with those conducted previously with lavender, rosemary, linalool, peppermint, marjoram, cardamom, sandalwood, basil and lime, we thus concluded that the sensory test described here might serve not only as a screening test for efficacy of aroma but also as a categorized table for aroma samples which can act as a reference to each other.

Voltage-gated proton channels (H(+) channels) are highly proton-selective transmembrane pathways. Although the primary determinants for activation are the pH and voltage gradients across the membrane, the current amplitudes fluctuate often when these gradients are constant. The aim of this study was to investigate the role of the intracellular pH (pHi) in regulating the availability of H(+) channels in osteoclasts and microglia. In whole-cell clamp recordings, the pHi was elevated after exposure to NH4Cl and returned to the control level after washout. However, the H(+) channel conductance did not recover fully when the exposure was prolonged (5 min). Similar results were observed in osteoclasts and microglia, but not in COS7 cells expressing a murine H(+) channel gene (mVSOP). As other electrophysiological properties, like the gating kinetics and voltage dependence for activation, were unchanged, the decreases in the H(+) channel conductance were probably due to the decreases in H(+) channels available at the plasma membrane. The decreases in the H(+) channel conductances were accompanied by reductions in the cell capacitance. Exposure to NH4Cl increased the uptake of the endocytosis marker FM1-43, substantiating the idea that pHi increases facilitated endocytosis. In osteoclasts, whose plasma membrane expresses V-ATPases and H(+) channels, pHi increases by these H(+)-transferring molecules in part facilitated endocytosis. The endocytosis and decreases in the H(+) channel conductance were reduced by dynasore, a dynamin blocker. These results suggest that pHi increases in osteoclasts and microglia decrease the numbers of H(+) channels available at the plasma membrane through facilitation of dynamin-dependent endocytosis.

A photochemical [2+2] cycloaddition reaction was executed in a microflow system using glass-made microchannels having 1000-μm width and 500-μm depth. The reaction of cyclohexenones with vinyl aceta...