Osteoporosis is a result of imbalance between bone formation by osteoblasts and resorption by osteoclasts (OCs). In the present study, we investigated the potential of limiting the aggravation of osteoporosis by reducing the activity of OCs through thermolysis. The proposed method is to synthesize bisphosphonate (Bis)-conjugated iron (II, III) oxide (Fe 3 O 4 ) nanoparticles and incorporate them into OCs. The cells should be subsequently exposed to radiofrequency (RF) to induce thermolysis. In this study, particles of Fe 3 O 4 were first synthesized by chemical co-precipitation and then coated with dextran (Dex). The Dex/Fe 3 O 4 particles were then conjugated with Bis to form Bis/Dex/Fe 3 O 4 . Transmission electron microscopy revealed that the average diameter of the Bis/Dex/Fe 3 O 4 particles was ~20 nm. All three kinds of nanoparticles were found to have cubic inverse spinel structure of Fe 3 O 4 by the X-ray diffraction analysis. Fourier transform infrared spectroscopy confirmed that the Dex/Fe 3 O 4 and Bis/Dex/Fe 3 O 4 nanoparticles possessed their respective Dex and Bis functional groups, while a superconducting quantum interference device magnetometer measured the magnetic moment to be 24.5 emu. In addition, the Bis/Dex/Fe 3 O 4 nanoparticles were fully dispersed in double-distilled water. Osteoblasts and OCs were individually cultured with the nanoparticles, and an MTT assay revealed that they were non-cytotoxic. An RF system (42 kHz and 450 A) was used to raise the temperature of the nanoparticles for 20 minutes, and the thermal effect was found to be sufficient to destroy OCs. Furthermore, in vivo studies verified that nanoparticles were indeed magnetic resonance imaging contrast agents and that they accumulated after being injected into the body of rats. In conclusion, we developed a water-dispersible magnetic nanoparticle that had RF-induced thermogenic properties, and the results indicated that the Bis/Dex/Fe 3 O 4 nanoparticle had the potential for controlling osteoporosis.

Valproic acid (VA) is currently used to treat epilepsy and bipolar disorder. It has also been demonstrated to promote neuroprotection and neurogenesis. Although beneficial actions of VA on brain blood vessels have also been demonstrated, the effects of VA on brain endothelial cell (EC) Ca signaling are hitherto unreported. In this report, we examined the effects of VA on agonist-triggered Ca signaling in mouse cortical bEND.3 EC. While VA (100 μm) did not cause an acute inhibition of ATP-triggered Ca signaling, a 30-min VA treatment strongly suppressed ATP-triggered intracellular Ca release; however, such treatment did not affect Ca release triggered by cyclopiazonic acid, an inhibitor of SERCA Ca pump, suggesting there was no reduction in Ca store size. VA-activated p38 signaling, and VA-induced inhibition of ATP-triggered Ca release was prevented by SB203580, a p38 inhibitor, suggesting VA caused the inhibition by activating p38. Remarkably, VA treatment did not affect acetylcholine-triggered Ca release, suggesting VA may not inhibit inositol 1,4,5-trisphosphate-induced Ca release per se, and may not act directly on Gq or phospholipase C. Taken together, our results suggest VA treatment, via a p38-dependent mechanism, led to an inhibition of purinergic receptor-effector coupling.

Ca2+-sensing receptors (CaSR), activated by elevated concentrations of extracellular Ca2+, have been known to regulate functions of thyroid cells, neurons, and endothelial cells (EC). In this report, we studied CaSR-mediated Ca2+ influx in mouse cerebral microvascular EC (bEND.3 cells). Cytosolic free Ca2+ concentration and Mn2+ influx were measured by fura-2 microfluorometry. High (3 mM) Ca2+ (CaSR agonist), 3 mM spermine (CaSR agonist), and 10 μM cinacalcet (positive allosteric modulator of CaSR) all triggered Ca2+ influx; however, spermine, unlike high Ca2+ and cinacalcet, did not promote Mn2+ influx and its response was poorly sensitive to SKF 96365, a TRP channel blocker. Consistently, 2-aminoethoxydiphenyl borate and ruthenium red (two other general TRP channel blockers) suppressed Ca2+ influx triggered by cinacalcet and high Ca2+ but not by spermine. Ca2+ influx triggered by high Ca2+, spermine, and cinacalcet was similarly suppressed by A784168, a potent and selective TRPV1 antagonist. Our results suggest that CaSR activation triggered Ca2+ influx via TRPV1 channels; intriguingly, pharmacological, and permeability properties of such Ca2+ influx depended on the stimulating ligands.

Afatinib is used to treat non‐small cell lung cancer cells (NSCLC), and its mechanism involves irreversible inhibition of epidermal growth factor receptor (EGFR) tyrosine kinase. In this study, we examined if afatinib had cytotoxic action against NSCLC other than inhibition of tyrosine kinase. Afatinib (1–30 μM) caused apoptotic death in A549 NSCLC in a concentration‐dependent manner. Afatinib triggered Ca2+ influx without causing Ca2+ release, and the Ca2+ influx was unaffected by sodium orthovanadate (SOV, an inhibitor of tyrosine phosphatase), suggesting that afatinib‐triggered Ca2+ response was unrelated to its inhibition of tyrosine kinase. Addition of afatinib also promoted Mn2+ influx. Ca2+ influx triggered by afatinib was resistant to SKF96365 and ruthenium red (two general blockers of TRP channels) and, unexpectedly, Ni2+ (a non‐specific Ca2+ channel blocker). Afatinib caused an increase in mitochondrial Ca2+ level, an initial mitochondrial hyperpolarization (4 h) and followed by mitochondrial potential collapse (24–48 h). Afatinib‐induced cell death was slightly but significantly alleviated in low extracellular Ca2+ condition or under pharmacological block of mitochondrial permeability transition pore (MPTP) opening by cyclosporin A. Therefore, in addition to tyrosine kinase inhibition as a major anti‐cancer mechanism of afatinib, stimulation of an atypical Ca2+ influx pathway, mitochondrial Ca2+ overload, and potential collapse in part contribute to afatinib‐induced cell death.