Cesium chloride

Potassium channel blocker; inhibits the pacemaker current (I_f) and the hyperpolarization-activated cationic current (I_h). Prevents activation of caspase-3 and neuronal apoptosis in serum- and potassium-deprived cerebellar granule neurons by inactivating GSK-3β.

Comparative Analysis of Cesium Chloride- and Iodixanol-Based Purification of Recombinant Adeno-Associated Viral Vectors for Preclinical Applications.[Pubmed:26222983]

Hum Gene Ther Methods. 2015 Aug;26(4):147-57.

Cesium chloride (CsCl)- and iodixanol-based density gradients represent the core step in most protocols for serotype-independent adeno-associated virus (AAV) purification established to date. However, despite controversial reports about the purity and bioactivity of AAV vectors derived from each of these protocols, systematic comparisons of state-of-the-art variants of these methods are sparse. To define exact conditions for such a comparison, we first fractionated both gradients to analyze the distribution of intact, bioactive AAVs and contaminants, respectively. Moreover, we tested four different polishing methods (ultrafiltration, size-exclusion chromatography, hollow-fiber tangential flow filtration, and polyethylene glycol precipitation) implemented after the iodixanol gradient for their ability to deplete iodixanol and protein contaminations. Last, we conducted a side-by-side comparison of the CsCl and iodixanol/ultrafiltration protocol. Our results demonstrate that iodixanol-purified AAV preparations show higher vector purity but harbor more ( approximately 20%) empty particles as compared with CsCl-purified vectors (<1%). Using mass spectrometry, we analyzed prominent protein impurities in the AAV vector product, thereby identifying known and new, possibly AAV-interacting proteins as major contaminants. Thus, our study not only provides a helpful guide for the many laboratories entering the AAV field, but also builds a basis for further investigation of cellular processes involved in AAV vector assembly and trafficking.

Low-Temperature Anharmonicity in Cesium Chloride (CsCl).[Pubmed:28211260]

Angew Chem Int Ed Engl. 2017 Mar 20;56(13):3625-3629.

Anharmonic lattice vibrations govern heat transfer in materials, and anharmonicity is commonly assumed to be dominant at high temperature. The textbook cubic ionic defect-free crystal CsCl is shown to have an unexplained low thermal conductivity at room temperature (ca. 1 W/(m K)), which increases to around 13 W/(m K) at 25 K. Through high-resolution X-ray diffraction it is unexpectedly shown that the Cs atomic displacement parameter becomes anharmonic at 20 K.

High Chloride Doping Levels Stabilize the Perovskite Phase of Cesium Lead Iodide.[Pubmed:27135266]

Nano Lett. 2016 Jun 8;16(6):3563-70.

Cesium lead iodide possesses an excellent combination of band gap and absorption coefficient for photovoltaic applications in its perovskite phase. However, this is not its equilibrium structure under ambient conditions. In air, at ambient temperature it rapidly transforms to a nonfunctional, so-called yellow phase. Here we show that chloride doping, particularly at levels near the solubility limit for chloride in a cesium lead iodide host, provides a new approach to stabilizing the functional perovskite phase. In order to achieve high doping levels, we first co-deposit colloidal nanocrystals of pure cesium lead chloride and cesium lead iodide, thereby ensuring nanometer-scale mixing even at compositions that potentially exceed the bulk miscibility of the two phases. The resulting nanocrystal solid is subsequently fused into a polycrystalline thin film by chemically induced, room-temperature sintering. Spectroscopy and X-ray diffraction indicate that the chloride is further dispersed during sintering and a polycrystalline mixed phase is formed. Using density functional theory (DFT) methods in conjunction with nudged elastic band techniques, low-energy pathways for interstitial chlorine diffusion into a majority-iodide lattice were identified, consistent with the facile diffusion and fast halide exchange reactions observed. By comparison to DFT-calculated values (with the PBE exchange-correlation functional), the relative change in band gap and the lattice contraction are shown to be consistent with a Cl/I ratio of a few percent in the mixed phase. At these incorporation levels, the half-life of the functional perovskite phase in a humid atmosphere increases by more than an order of magnitude.

Application of GelGreen in Cesium Chloride Density Gradients for DNA-Stable Isotope Probing Experiments.[Pubmed:28056074]

PLoS One. 2017 Jan 5;12(1):e0169554.

In this study, GelGreen was investigated as a replacement for SYBR(R) Safe to stain DNA in Cesium chloride (CsCl) density gradients for DNA-stable isotope probing (SIP) experiments. Using environmental DNA, the usage of GelGreen was optimized for sensitivity compared to SYBR(R) Safe, its optimal concentration, detection limit for environmental DNA and its application in environmental DNA-SIP assay. Results showed that GelGreen was more sensitive than SYBR(R) Safe, while the optimal dosage (15X concentration) needed was approximately one-third of SYBR(R) Safe, suggesting that its sensitivity was three times more superior than SYBR(R) Safe. At these optimal parameters, the detection limit of GelGreen-stained environmental DNA was as low as 0.2 mug, but the usage of 0.5 mug environmental DNA was recommended to produce a more consistent DNA band. In addition, a modified needle extraction procedure was developed to withdraw DNA effectively by fractionating CsCl density gradients into four or five fractions. The successful application of GelGreen staining with 13C-labeled DNA from enriched activated sludge suggests that this stain was an excellent alternative of SYBR(R) Safe in CsCl density gradients for DNA-SIP assays.

Magnesium sulfate suppresses L-type calcium currents on the basilar artery smooth muscle cells in rabbits.[Pubmed:22450340]

Neurol Res. 2012 Apr;34(3):291-6.

OBJECTIVES: Although magnesium is a well-known treatment for vasospasm following subarachnoid hemorrhage, its mechanism of action for cerebral vascular relaxation is not clear. In addition, it is known that L-type calcium (Ca(2+)) channels play a pivotal role in smooth muscle contraction. To investigate the role of L-type Ca(2+) channels in the magnesium-induced relaxation of basilar smooth muscle cells, we examined the effect of magnesium sulfate on L-type Ca(2+) currents using freshly isolated smooth muscle cells from rabbit basilar arteries. METHOD: Rabbits were anesthetized with ketamine (50 mg/kg) with xylazine (25 mg/kg) and exsanguinated. Smooth muscle cells were isolated from rabbit basilar arteries by enzyme treatment. Cells were stored at 4 degrees C before use. Whole-cell patch clamp technique was used to identify L-type Ca(2+) currents, using the potassium channel blocker, Cesium chloride, and nimodipine and Bay K8644 as a blocker and activator of L-type Ca(2+) channels, respectively. RESULTS: Inward currents induced by step pulses were significantly reduced by nimodipine (n = 5, P<0.05) and increased by Bay K8644 (n = 5, P<0.05). The L-type Ca(2+) currents (122+/-14.0 pA, n = 12) were significantly reduced by the application of 5 mM magnesium sulfate (28+/-4 pA, n = 12, P<0.05). The inward currents enhanced by Bay K8644 were further suppressed by the application of magnesium sulfate. DISCUSSION: These results demonstrate that L-type Ca(2+) channels are functionally expressed in rabbit basilar smooth muscle cells and suggest that L-type Ca(2+) channels may play a pivotal role for magnesium-induced relaxation.

Cesium chloride protects cerebellar granule neurons from apoptosis induced by low potassium.[Pubmed:17804190]

Int J Dev Neurosci. 2007 Oct;25(6):359-65.

Neuronal apoptosis plays a critical role in the pathogenesis of neurodegenerative disorders, and neuroprotective agents targeting apoptotic signaling could have therapeutic use. Here we report that Cesium chloride, an alternative medicine in treating radiological poison and cancer, has neuroprotective actions. Serum and potassium deprivation induced cerebellar granule neurons to undergo apoptosis, which correlated with the activation of caspase-3. Cesium prevented both the activation of caspase-3 and neuronal apoptosis in a dose-dependent manner. Cesium at 8 mM increased the survival of neurons from 45 +/- 3% to 91 +/- 5% of control. Cesium's neuroprotection was not mediated by PI3/Akt or MAPK signaling pathways, since it was unable to activate either Akt or MAPK by phosphorylation. In addition, specific inhibitors of PI3 kinase and MAP kinase did not block cesium's neuroprotective effects. On the other hand, cesium inactivated GSK3beta by phosphorylation of serine-9 and GSK3beta-specific inhibitor SB415286 prevented neuronal apoptosis. These data indicate that cesium's neuroprotection is likely via inactivating GSK3beta. Furthermore, cesium also prevented H(2)O(2)-induced neuronal death (increased the survival of neurons from 72 +/- 4% to 89 +/- 3% of control). Given its relative safety and good penetration of the brain blood barrier, our findings support the potential therapeutic use of cesium in neurodegenerative diseases.