MicroRNA-552 deficiency mediates 5-fluorouracil resistance by targeting SMAD2 signaling in DNA-mismatch-repair-deficient colorectal cancer.

OBJECTIVE: Although DNA-mismatch-repair-deficient (dMMR) status and aberrant expression of miRNAs are both critically implicated in the pathogenesis of resistance to 5-fluorouracil (5-FU) in colorectal cancer (CRC), whether these two factors regulate tumor response to 5-FU in a coordinated manner remains unknown. This study is designed to elucidate whether changes in miR-552 expression levels correlate to 5-FU-based chemoresistance in CRC, and to further identify the putative targets of miR-552 using multiple approaches. METHODS: miR-552 expression was assessed in 5-FU-resistant CRC tissues and cells using real-time PCR. Effects of miR-552 dysregulation on 5-FU resistance in CRC cells were determined by measuring cell viability, apoptosis and in vivo oncogenic capacity. Finally, we studied the posttranscriptional regulation of SMAD2 by miR-552 using multiple approaches including luciferase reporter assay, site-directed mutagenesis and transient/stable transfection, at molecular and functional levels. RESULTS: Expression of miR-552 was significantly downregulated in 5-FU-resistant CRC tissues and cells, and this downregulation, regulated by dMMR, was associated with poor postchemotherapy prognosis. Functionally, forced expression of miR-552 exhibited a proapoptotic effect and attenuated 5-FU resistance, whereas inhibition of miR-552 expression potentiated 5-FU resistance in CRC cells. Mechanically, miR-552 directly targeted the 3'-UTR of SMAD2, and stable ablation of SMAD2 neutralized the promoting effects of miR-552 deficiency-induced 5-FU resistance. CONCLUSIONS: Overall, our findings have revealed a critical role of miR-552/SMAD2 cascade in modulating cellular response to 5-FU chemotherapy. miR-552 may act as an efficient mechanistic link synchronizing dMMR and 5-FU resistance in CRC.

Salidroside improved cerebrovascular vasodilation in streptozotocin-induced diabetic rats through restoring the function of BKCa channel in smooth muscle cells.

Vessel disease is a kind of severe complication in diabetic patients. However, few pharmacologic agents can directly recover diabetic vascular function. Salidroside (SAL), a major ingredient from Rhodiola rosea, has been found to have an obvious hypoglycemic effect and a beneficial protection on vascular function in diabetes. However, whether SAL is a suitable treatment for diabetes has not so far been evaluated and the underlying mechanisms remain unknown. The present work aims to (1) investigate the potential effects of SAL on cerebrovascular relaxation in streptozotocin-induced diabetic rats or when exposed to acute hyperglycemia condition and (2) examine whether function of the BKCa channel is involved in SAL treatment for diabetic vascular relaxation. Our results indicate that chronic administration of 100 mg/kg/day SAL not only improves cerebrovascular relaxation but also increases BKCa ß1-subunit expressions at both protein and mRNA levels and enhances BKCa whole-cell and single-channel activities in cerebral VSMCs of diabetic rats. Correspondingly, acute application of 100 µM SAL induces cerebrovascular relaxation by activation of the BKCa channel. Furthermore, SAL activated the BKCa channel mainly through acting on the ß1-subunit in HEK293 cells transfected with hSloα+ß1 constructs. We concluded that SAL improved vasodilation in diabetic rats through restoring the function of the BKCa-ß1 subunit in cerebrovascular smooth muscle cells, which may be the underlying mechanism responsible for the vascular protection of SAL in diabetes.

Berberine reduced blood pressure and improved vasodilation in diabetic rats.

Hyperglycemia and hypertension are considered to be the two leading risk factors for vascular disease in diabetic patients. However, few pharmacologic agents could provide a combinational therapy for controlling hyperglycemia and hypertension at the same time in diabetes. The objectives of this study are to investigate whether berberine treatment could directly reduce blood pressure and identify the molecular mechanism underlying the vascular protection of berberine in diabetic rats. Berberine was intragastrically administered with different dosages of 50, 100 and 200 mg/kg/day to diabetic rats for 8 weeks since the injection of streptozotocin. The endothelium-dependent/-independent relaxation in middle cerebral arteries was investigated. The activity of large-conductance Ca2+-activated K+ channel (BKCa) was investigated by recording whole-cell currents, analyzing single-channel activities and assessing the expressions of α- and ß1-subunit at protein or mRNA levels. Results of the study suggest that chronic administration of 100 mg/kg/day berberine not only lowered blood glucose but also reduced blood pressure and improved vasodilation in diabetic rats. Furthermore, berberine markedly increased the function and expression of BKCa ß1-subunit in cerebral vascular smooth muscle cells (VSMCs) isolated from diabetic rats or when exposed to hyperglycemia condition. The present study provided initial evidences that berberine reduced blood pressure and improved vasodilation in diabetic rats by activation of BKCa channel in VSMCs, which suggested that berberine might provide a combinational therapy for controlling hyperglycemia and blood pressure in diabetes. Furthermore, our work indicated that activation of BKCa channel might be the underlying mechanism responsible for the vascular protection of berberine in diabetes.

Salidroside contributes to reducing blood pressure and alleviating cerebrovascular contractile activity in diabetic Goto-Kakizaki Rats by inhibition of L-type calcium channel in smooth muscle cells.

BACKGROUND: Vascular disease is a common and often severe complication in diabetes mellitus. Hyperglycemia and hypertension are considered to be two of the leading risk factors for vascular complications in diabetic patients. However, few pharmacologic agents could provide a combinational therapy for controlling hyperglycemia and blood pressure in diabetic patients at the same time. Salidroside (SAL) is the major active ingredient derived from Rhodiola. Recently, it has been reported that SAL have an obvious hypoglycemic effect in diabetes and show a beneficial activity in diabetic vascular dysfunction. However, it remains unknown whether or not SAL treatment could directly reduce blood pressure in diabetes. Furthermore, it is not clear what is the molecular mechanism underlying the vascular protection of SAL treatment in diabetes. METHODS: Male diabetic Goto-Kakizaki (GK) and non-diabetic control Wistar-Kyoto (WKY) rats were administrated with different dosages of SAL (50, 100 and 200 mg/kg/day) for 4 weeks. Contractile responsiveness of cerebral artery to KCl or 5-HT was investigated by Pressure Myograph System. The activity of CaL channel was investigated by recording whole-cell currents, assessing the expressions of CaL channel α1C-subunit and its downstream kinase, MLCK, at protein or mRNA levels. RESULTS: We showed that administration of 100 mg/kg/day SAL for 4 weeks not only lowered blood glucose, but also reduced blood pressure and alleviated cerebrovascular contractile activity in diabetic GK rats, which suggested that SAL treatment may provide a combinational therapy for lowering blood glucose and reducing blood pressure in diabetes at the same time. Furthermore, SAL treatment markedly inhibited the function and expression of CaL channel in cerebral VSMCs isolated from diabetic GK rats or when exposed to hyperglycemia condition, which may be the underlying mechanism responsible for the vascular protection of SAL in diabetes. CONCLUSIONS: The present study provided evidences that SAL contributes to reducing blood pressure and alleviating cerebrovascular contractile activity in diabetic GK rats by inhibition of CaL channel in smooth muscle cells, which may provide a novel approach to treat vascular complications in diabetic patients.

Knockdown of Tripartite Motif-Containing Protein 37 (TRIM37) Inhibits the Proliferation and Tumorigenesis in Colorectal Cancer Cells.

Tripartite motif-containing protein 37 (TRIM37), a new member of the RING-B-box-coiled-coil (RBCC) subfamily of zinc finger proteins, was found to be involved in the development and progression of several cancers. However, the expression pattern and biological functions of TRIM37 in colorectal cancer (CRC) remain unknown. Therefore, in the present study, we examined the expression pattern of TRIM37 in CRC and investigated the function of TRIM37 in the progression of CRC. Our results showed that TRIM37 expression was upregulated in CRC cell lines. Knockdown of TRIM37 inhibited CRC cell proliferation and tumor growth in vivo. Furthermore, knockdown of TRIM37 inhibited the migration and invasion in CRC cells. Last, knockdown of TRIM37 inhibited the protein level expression of ß-catenin, cyclin D1, and c-Myc in CRC cells. In conclusion, these results demonstrate that TRIM37 may play an important role in the proliferation, invasion, and tumorigenesis of CRC cells. Thus, TRIM37 may be a potential therapeutic target for the treatment of CRC.

Organic two-photon nanoparticles modulate reactive oxygen species, intracellular calcium concentration, and mitochondrial membrane potential during apoptosis of human gastric carcinoma SGC-7901 cells.

OBJECTIVES: To investigate the biocompatibility of human gastric carcinoma cells (SGC-7901) with organic two-photon nanoparticles (NPs). RESULTS: Different concentrations of NPs were incubated with SGC-7901 cells for different times. The levels of cell apoptosis, reactive oxygen species (ROS), intracellular calcium, and mitochondrial membrane potential (MMP) were measured by staining the SGC-7901 cells with Annexin V-FITC/PI, 2',7'-dichlorofluorescin diacetate, Fluo-3 AM, and Rhodamine 123, followed by the flow cytometry assay. NPs at <4 µg/ml, did not have any significant effect on apoptosis, necrosis, generation of ROS, increase of intracellular Ca(2+) concentration or decrease of MMP in SGC-7901 cells, but >4 µg/ml had a major effects on all the above mentioned parameters. CONCLUSION: 2,5,2',5'-Tetra(4-N,N-diphenylamine styryl) biphenyl NPs can be used at an appropriate concentration as a safe drug carrier or imaging marker and may serve as an effective tool for developing a photodynamic cancer therapy.

Berberine alleviates the cerebrovascular contractility in streptozotocin-induced diabetic rats through modulation of intracellular Ca²âº handling in smooth muscle cells.

BACKGROUND: Vascular dysfunction is a distinctive phenotype in diabetes mellitus. Current treatments mostly focus on the tight glycemic control and few of these treatments have been designed to directly recover the vascular dysfunction in diabetes. As a classical natural medicine, berberine has been explored as a possible therapy for DM. In addition, it is reported that berberine has an extra-protective effect in diabetic vascular dysfunction. However, little is known whether the berberine treatment could ameliorate the smooth muscle contractility independent of a functional endothelium under hyperglycemia. Furthermore, it remains unknown whether berberine affects the arterial contractility by regulating the intracellular Ca(2+) handling in vascular smooth cells (VSMCs) under hyperglycemia. METHODS: Sprague-Dawley rats were used to establish the diabetic model with a high-fat diet plus injections of streptozotocin (STZ). Berberine (50, 100, and 200 mg/kg/day) were intragastrically administered to control and diabetic rats for 8 weeks since the injection of STZ. The intracellular Ca(2+) handling of isolated cerebral VSMCs was investigated by recording the whole-cell L-type Ca(2+) channel (CaL) currents, assessing the protein expressions of CaL channel, and measuring the intracellular Ca(2+) in response to caffeine. Our results showed that chronic administration of 100 mg/kg/day berberine not only reduced glucose levels, but also inhibited the augmented contractile function of cerebral artery to KCl and 5-hydroxytryptamine (5-HT) in diabetic rats. Furthermore, chronic administration of 100 mg/kg/day berberine significantly inhibited the CaL channel current densities, reduced the α1C-subunit expressions of CaL channel, decreased the resting intracellular Ca(2+) ([Ca(2+)]i) level, and suppressed the Ca(2+) releases from RyRs in cerebral VSMCs isolated from diabetic rats. Correspondingly, acute application of 10 µM berberine could directly inhibit the hyperglycemia-induced CaL currents and suppress the hyperglycemia-induced Ca(2+) releases from RyRs in cerebral VSMCs isolated from normal control rats. CONCLUSIONS: Our study indicated that berberine alleviated the cerebral arterial contractility in the rat model of streptozotocin-induced diabetes via regulating the intracellular Ca(2+) handling of smooth muscle cells.

Knockdown of SPOCK1 Inhibits the Proliferation and Invasion in Colorectal Cancer Cells by Suppressing the PI3K/Akt Pathway.

Sparc/osteonectin, cwcv, and kazal-like domains proteoglycan (testican) 1 (SPOCK1), known as testican-1, were found to be involved in the development and progression of tumors. However, in colorectal cancer (CRC), the expression pattern of SPOCK1 and its functional role remain poorly investigated. In the present study, we explored the role of SPOCK1 in CRC. Our results demonstrated that SPOCK1 is overexpressed in CRC cell lines. SPOCK1 silencing significantly inhibited the proliferation in vitro and the tumor growth in vivo. Furthermore, SPOCK1 silencing significantly attenuated the migration/invasion by reversing the EMT process in CRC cells. Finally, knockdown of SPOCK1 obviously decreased the protein expression levels of p-PI3K and p-Akt in HCT116 cells. In total, our study demonstrated for the first time that knockdown of SPOCK1 inhibits the proliferation and invasion in CRC cells, possibly through the PI3K/Akt signaling pathway. Therefore, SPOCK1 may be a potential therapeutic target for the treatment of CRC.

Donor-acceptor-type copolymers based on a naphtho[1,2-c:5,6-c]bis(1,2,5-thiadiazole) scaffold for high-efficiency polymer solar cells.

Four donor-acceptor-type low-bandgap conjugated polymers based on a naphtho[1,2-c:5,6-c]bis(1,2,5-thiadiazole) (NT) acceptor and different donors bridged by a bithiophene spacer have been synthesized through Suzuki or Stille polymerization reactions. Fluorene (F), carbazole (Cz), alkylidene fluorene (AF), and benzodithiophene (BDT) were selected as the donor units to produce a series of new conjugated polymers. Owing to the different electron-donating ability of the donor units, the energy levels, absorption spectra, bandgaps, and carrier mobilities of the resulting polymers were systematically tuned. Bulk-heterojunction-type polymer solar cells based on the new polymers and [6,6]-phenyl-C61 -butyric acid methyl ester (PC61 BM) or [6,6]-phenyl-C71 -butyric acid methyl ester (PC71 BM) were investigated and all of the devices exhibited good photovoltaic performance, with power-conversion efficiencies (PCEs) over 3 %. The best device performance was achieved by PF-C12NT, with an open-circuit voltage (Voc ) of 0.87 V, a short-circuit current density (Jsc ) of 12.19 mA cm(-2) , a fill factor (FF) of 61.36 %, and a PCE of 6.51 % under simulated sunlight (100 mW cm(-2) , AM 1.5G).

Investigation on "Excimer" Formation Mechanism of Linear Oligofluorenes-Functionalized Anthracenes by Using Transient Absorption Spectroscopy.

We study the photophysical characters of two oligofluorenes-functionalized anthracenes molecules with different fluorine-vinylene (FV) units, which exhibits that "excimer" state appears in the solution after photoexcitation. The dynamic data shows that two mechanisms are responsible for the generation of "excimer". The fast one is controlled by the arene-arene interaction between molecules and the slow one is influenced by the diffusion motion of molecules. Increasing the number of FV units may suppress the DM-dependent "excimer" and enhance the yield of intrinsic fluorescence, which finally improves the fluorescence property of molecules in solution.

Anti-angiogenic effect of the total flavonoids in Scutellaria barbata D. Don.

BACKGROUND: Angiogenesis is closely related to the growth, invasion and metastasis of tumors, also considered as the key target of anticancer therapy. Scutellaria barbata D. Don (S. barbata), a traditional Chinese medicine, is being used to treat various diseases, including cancer. However, the antitumor molecular mechanism of S. barbata was still unclear. This study aimed to investigate the inhibitory effects of the total flavones in S. barbata (TF-SB) on angiogenesis. METHODS: Human umbilical vein endothelial cells (HUVECs) were treated with various concentrations of TF-SB. Cell viability was examined using the MTT assay. The scratch assay was used to detect the migration of HUVECs after treatment with TF-SB. The ability of HUVECs to form network structures in vitro was demonstrated using the tube formation assay. The chick embryo chorioallantoic membrane assay was performed to detect the in vivo anti-angiogenic effect. The expression of VEGF was measured by the enzyme-linked immunosorbent. RESULTS: Results showed that TF-SB inhibited the proliferation and migration of HUVECs in a dose- dependent manner. Simultaneously, TF-SB significantly suppressed HUVEC angiogenesis in vitro and in vivo. Furthermore, VEGF was downregulated in both HUVECs and MHCC97-H cells after TF-SB treatment. CONCLUSION: TF-SB could suppress the process of angiogenesis in vitro and in vivo. TF-SB potentially suppresses angiogenesis in HUVECs by regulating VEGF. These findings suggested that TF-SB may serve as a potent anti-angiogenic agent.

Targeted inhibition of mammalian target of rapamycin (mTOR) enhances radiosensitivity in pancreatic carcinoma cells.

The mammalian target of rapamycin (mTOR) is a protein kinase that regulates protein translation, cell growth, and apoptosis. Rapamycin (RPM), a specific inhibitor of mTOR, exhibits potent and broad in vitro and in vivo antitumor activity against leukemia, breast cancer, and melanoma. Recent studies showing that RPM sensitizes cancers to chemotherapy and radiation therapy have attracted considerable attention. This study aimed to examine the radiosensitizing effect of RPM in vitro, as well as its mechanism of action. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and colony formation assay showed that 10 nmol/L to 15 nmol/L of RPM had a radiosensitizing effects on pancreatic carcinoma cells in vitro. Furthermore, a low dose of RPM induced autophagy and reduced the number of S-phase cells. When radiation treatment was combined with RPM, the PC-2 cell cycle arrested in the G2/M phase of the cell cycle. Complementary DNA (cDNA) microarray and reverse transcription polymerase chain reaction (RT-PCR) revealed that the expression of DDB1, RAD51, and XRCC5 were downregulated, whereas the expression of PCNA and ABCC4 were upregulated in PC-2 cells. The results demonstrated that RPM effectively enhanced the radiosensitivity of pancreatic carcinoma cells.

Multipoint interactions enhanced CO2 uptake: a zeolite-like zinc-tetrazole framework with 24-nuclear zinc cages.

A zeolite-like microporous tetrazole-based metal-organic framework (MOF) with 24 nuclear zinc cages was synthesized and characterized. It exhibits high CO(2) adsorption capacity up to 35.6 wt % (8.09 mmol/g) and excellent CO(2)/CH(4) selectivity at 273 K/1 bar, being among the highest values known to date. Theoretical calculations based on simulated annealing techniques and periodic DFT revealed that CO(2) is predominantly located around the inner surface of the cages through multipoint interactions, in particular, around the aromatic tetrazole rings. Importantly, it is the first time that multipoint interactions between CO(2) molecules and frameworks resulting in high CO(2) uptake are observed.

Activation of BK(Ca) channels in zoledronic acid-induced apoptosis of MDA-MB-231 breast cancer cells.

BACKGROUND: Zoledronic acid, one of the most potent nitrogen-containing biphosphonates, has been demonstrated to have direct anti-tumor and anti-metastatic properties in breast cancer in vitro and in vivo. In particular, tumor-cell apoptosis has been recognized to play an important role in the treatment of metastatic breast cancer with zoledronic acid. However, the precise mechanisms remain less clear. In the present study, we investigated the specific role of large conductance Ca(2+)-activated potassium (BK(Ca)) channel in zoledronic acid-induced apoptosis of estrogen receptor (ER)-negative MDA-MB-231 breast cancer cells. METHODOLOGY/PRINCIPAL FINDINGS: The action of zoledronic acid on BK(Ca) channel was investigated by whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry, analysis of fragmented DNA by agarose gel electrophoresis, and flow cytometry assays. Cell proliferation was investigated by MTT test and immunocytochemistry. In addition, such findings were further confirmed with human embryonic kidney 293 (HEK293) cells which were transfected with functional BK(Ca) α-subunit (hSloα). Our results clearly indicated that zoledronic acid directly increased the activities of BK(Ca) channels, and then activation of BK(Ca) channel by zoledronic acid contributed to induce apoptosis in MDA-MB-231 cells. The possible mechanisms were associated with the elevated level of intracellular Ca(2+) and a concomitant depolarization of mitochondrial membrane potential (Δψm) in MDA-MB-231 cells. CONCLUSIONS: Activation of BK(Ca) channel was here shown to be a novel molecular pathway involved in zoledronic acid-induced apoptosis of MDA-MB-231 cells in vitro.

Prawn lipocalin: characterization of a color shift induced by gene knockdown and ligand binding assay.

The lipocalin family of proteins functions in the transport of steroids, carotenoids, retinoids, and other small hydrophobic molecules. Recently, a lipocalin (MrLC) was isolated from the prawn Macrobrachium rosenbergii and its expression varied with the molting cycle. In this study, knockdown of the MrLC gene by RNA interference (RNAi) was performed and resulted in a shift in body color from blue to orangish red over the entire carapace. By immune-gold electron microscopy, MrLC was found to co-localize with the lipid droplets in subepidermal adiose tissue that were found to be decreased dramatically in MrLC knockdown prawns, in which a reduction in relative fat content was also quantified. Furthermore, MrLC was found to specifically bind astaxanthin and molt hormone (20-hydroxyecdysone) in both in vitro ligand binding assay and in vivo native ligand detection. These results suggested that MrLC plays roles in the regulation of coloration through its association with astaxanthin and may also be involved in the regulation of molting in crustacean.

Differential regulation and recovery of intracellular Ca2+ in cerebral and small mesenteric arterial smooth muscle cells of simulated microgravity rat.

BACKGROUND: The differential adaptations of cerebrovasculature and small mesenteric arteries could be one of critical factors in postspaceflight orthostatic intolerance, but the cellular mechanisms remain unknown. We hypothesize that there is a differential regulation of intracellular Ca(2+) determined by the alterations in the functions of plasma membrane Ca(L) channels and ryanodine-sensitive Ca(2+) releases from sarcoplasmic reticulum (SR) in cerebral and small mesenteric vascular smooth muscle cells (VSMCs) of simulated microgravity rats, respectively. METHODOLOGY/PRINCIPAL FINDINGS: Sprague-Dawley rats were subjected to 28-day hindlimb unweighting to simulate microgravity. In addition, tail-suspended rats were submitted to a recovery period of 3 or 7 days after removal of suspension. The function of Ca(L) channels was evaluated by patch clamp and Western blotting. The function of ryanodine-sensitive Ca(2+) releases in response to caffeine were assessed by a laser confocal microscope. Our results indicated that simulated microgravity increased the functions of Ca(L) channels and ryanodine-sensitive Ca(2+) releases in cerebral VSMCs, whereas, simulated microgravity decreased the functions of Ca(L) channels and ryanodine-sensitive Ca(2+) releases in small mesenteric VSMCs. In addition, 3- or 7-day recovery after removal of suspension could restore the functions of Ca(L) channels and ryanodine-sensitive Ca(2+) releases to their control levels in cerebral and small mesenteric VSMCs, respectively. CONCLUSIONS: The differential regulation of Ca(L) channels and ryanodine-sensitive Ca(2+) releases in cerebral and small mesenteric VSMCs may be responsible for the differential regulation of intracellular Ca(2+), which leads to the altered autoregulation of cerebral vasculature and the inability to adequately elevate peripheral vascular resistance in postspaceflight orthostatic intolerance.

High glucose alters apoptosis and proliferation in HEK293 cells by inhibition of cloned BK Ca channel.

It has been reported that diabetic vascular dysfunction is associated with impaired function of large conductance Ca(2+) -activated K(+) (BK(Ca) ) channels. However, it is unclear whether impaired BK(Ca) channel directly participates in regulating diabetic vascular remodeling by altering cell growth in response to hyperglycemia. In the present study, we investigated the specific role of BK(Ca) channel in controlling apoptosis and proliferation under high glucose concentration (25 mM). The cDNA encoding the α+ß1 subunit of BK(Ca) channel, hSloα+ß1, was transiently transfected into human embryonic kidney 293 (HEK293) cells. Cloned BK(Ca) currents were recorded by both whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry and analysis of fragmented DNA by agarose gel electrophoresis. Cell proliferation was investigated by flow cytometry assays, MTT test, and immunocytochemistry. In addition, the expression of anti-apoptotic protein Bcl-2, intracellular Ca(2+) , and mitochondrial membrane potential (Δψm) were also examined to investigate the possible mechanisms. Our results indicate that inhibition of cloned BK(Ca) channels might be responsible for hyperglycemia-altered apoptosis and proliferation in HEK-hSloα+ß1 cells. However, activation of BK(Ca) channel by NS1619 or Tamoxifen significantly induced apoptosis and suppressed proliferation in HEK-hSloα+ß1 cells under hyperglycemia condition. When rat cerebral smooth muscle cells were cultured in hyperglycemia, similar findings were observed. Moreover, the possible mechanisms underlying the activation of BK(Ca) channel were associated with decreased expression of Bcl-2, elevation of intracellular Ca(2+) , and a concomitant depolarization of Δψm in HEK-hSloα+ß1 cells. In conclusion, cloned BK(Ca) channel directly regulated apoptosis and proliferation of HEK293 cell under hyperglycemia condition.

Temporal dynamics of two-photon-pumped amplified spontaneous emission in slab organic crystals.

We have studied the ultrafast dynamics of two-photon-pumped amplified spontaneous emission (ASE) from a single crystal by the time-resolved fluorescence upconversion technique. With the increase of two-photon pump intensities, the emission decay time is dramatically shortened by 30 times (from 3ns to approximately 87 ps), and the energy migration rate is acutely enhanced when ASE occurs. The stripe length is also found to play an important role in the formation of the ASE. Meanwhile, the gain coefficient is evaluated to be 15cm(-1) for 560nm at an excitation intensity of 2.3mJ/pulse/cm(2) by the variable stripe length technique.

Efficient two-photon excited amplified spontaneous emission from organic single crystals.

E, E-1, 4-bis[4'-(N,N-dibutylamino)styryl]-2,5-dimethoxy-benzene (DBASDMB) organic crystals with high crystalline quality, large size and excellent optical properties are prepared. The linear and nonlinear properties in the crystal are comparatively studied. The relaxation dynamics pumped by two-photon are very similar with that pumped by one-photon. The crystal exhibits very strong two-photon excited fluorescence and amplified spontaneous emission. Efficient two-photon absorption, reasonably high fluorescent quantum efficiency, and high crystal quality together with stimulated emission make organic crystals ideal for the application in frequency upconversion and other optoelectronic fields.

Activation of BKCa channel is associated with increased apoptosis of cerebrovascular smooth muscle cells in simulated microgravity rats.

Cerebral arterial remodeling is one of the critical factors in the occurrence of postspaceflight orthostatic intolerance. We hypothesize that large-conductance calcium-activated K(+) (BK(Ca)) channels in vascular smooth muscle cells (VSMCs) may play an important role in regulating cerebrovascular adaptation during microgravity exposure. The aim of this work was to investigate whether activation of BK(Ca) channels is involved in regulation of apoptotic remodeling of cerebral arteries in simulated microgravity rats. In animal studies, Sprague-Dawley rats were subjected to 1-wk hindlimb unweighting to simulate microgravity. Alterations of BK(Ca) channels in cerebral VSMCs were investigated by patch clamp and Western blotting; apoptosis was assessed by electron microscopy and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling (TUNEL). To evaluate the correlation of BK(Ca) channel and apoptosis, channel protein and cell nucleus were double-stained. In cell studies, hSloalpha+beta1 channel was coexpressed into human embryonic kidney 293 (HEK293) cells to observe the effects of BK(Ca) channels on apoptosis. In rats, enhanced activities and expression of BK(Ca) channels were found to be correlated with increased apoptosis in cerebral VSMCs after simulated microgravity. In transfected HEK293 cells, activation of cloned BK(Ca) channel induced apoptosis, whereas inhibition of cloned BK(Ca) channel decreased apoptosis. In conclusion, activation of BK(Ca) channels is associated with increased apoptosis in cerebral VSMCs of simulated microgravity rats.