Ascorbic Acid Sensitizes Colorectal Carcinoma to the Cytotoxicity of Arsenic Trioxide via Promoting Reactive Oxygen Species-Dependent Apoptosis and Pyroptosis.

Arsenic trioxide (ATO) is an effective therapeutic agent against acute promyelocytic leukemia (APL); however, its anti-tumor effect on solid tumors such as colorectal cancer (CRC) is still in debate. Ascorbic acid (AA) also produces a selective cytotoxic activity against tumor cells. Here, we exploit the potential benefit of ATO/AA combination in generating cytotoxicity to CRC cells, which may lay the groundwork for the potential combinational chemotherapy of CRCs. According to the results, we found that ATO and AA effectively inhibited the viability of human CRC cells in a synergistic manner. AA and ATO corporately activated caspase-3 to trigger apoptosis and upregulated the expression of caspase-1 and promoted formation of inflammasomes to induce pyroptosis. Furthermore, the stimulation of reactive oxygen species (ROS) overproduction was demonstrated as a subcellular mechanism for apoptosis and pyroptosis induced by ATO/AA combination treatment. Our findings suggest that ATO combination with a conventional dosage of AA offers an advantage for killing CRC cells. The synergistic action of ATO/AA combination might be considered a plausible strategy for the treatment of CRC and perhaps other solid tumors as well.

Ginkgolic Acid, a SUMO-1 Inhibitor, Inhibits the Progression of Oral Squamous Cell Carcinoma by Alleviating SUMOylation of SMAD4.

Small ubiquitin-related modifiers (SUMO) represent a class of ubiquitin-like proteins that are conjugated, like ubiquitin, by a set of enzymes to form cellular regulatory proteins, and play key roles in the control of cell proliferation, differentiation, and apoptosis. We found that ginkgolic acid (GA) can significantly reduce cell vitality in a dose- and time-dependent manner and can also accelerate cyto-apoptosis in both Tca8113 and Cal-27 cells. Migration and wound-healing assays were executed to determine the anti-migration effect of GA in oral squamous cell carcinoma (OSCC) cell lines. GA represses transforming growth factor-ß1 (TGF-ß1)-induced epithelial-mesenchymal transition (EMT) markers in OSCC cell lines. This investigation is the first evidence that GA suppresses TGF-ß1-induced SUMOylation of SMAD4. We show that GA affects the phosphorylation of SMAD2/3 protein and the release of SMAD4. In the xenograft mouse model, the OSCC progression was reduced by GA, effectively suppressing the growth of tumors. In addition, siSMAD4 improved cell migration and viability, which was inhibited by GA in Tca8113 cells. GA suppresses tumorigenicity and tumor progression of OSCC through inhibition of TGF-ß1-induced enhancement of SUMOylation of SMAD4. Thus, GA could be a promising therapeutic for OSCC.

Analgesic mechanism of acupuncture on neuropathic pain / 中国针灸

The research progress of acupuncture analgesia in recent years is analyzed to summarize the analgesic mechanism of acupuncture on neuropathic pain. The analgesic mechanism of acupuncture on neuropathic pain is discussed from peripheral level and central level, including peripheral sensitization and immune inflammatory response, changes of ion channel, central sensitization, regulation of cell signal pathway, activation of spinal glial cells, etc. It is suggested that the focus of future research should include conducting in-vitro studies with the help of multi-omics technology to detect the changes of metabolic substances and signal pathway molecules in patients with neuropathic pain before and after acupuncture to further clarify the mechanism of acupuncture analgesia.

TGF-ß1-PML SUMOylation-peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) form a positive feedback loop to regulate cardiac fibrosis.

Transforming growth factor-ß (TGF-ß) signaling pathway is involved in fibrosis in most, if not all forms of cardiac diseases. Here, we evaluate a positive feedback signaling the loop of TGF-ß1/promyelocytic leukemia (PML) SUMOylation/Pin1 promoting the cardiac fibrosis. To test this hypothesis, the mice underwent transverse aortic constriction (3 weeks) were developed and the morphological evidence showed obvious interstitial fibrosis with TGF-ß1, Pin1 upregulation, and increase in PML SUMOylation. In neonatal mouse cardiac fibroblasts (NMCFs), we found that exogenous TGF-ß1 induced the upregulation of TGF-ß1 itself in a time- and dose-dependent manner, and also triggered the PML SUMOylation and the formation of PML nuclear bodies (PML-NBs), and consequently recruited Pin1 into nuclear to colocalize with PML. Pharmacological inhibition of TGF-ß signal or Pin1 with LY364947 (3 µM) or Juglone (3 µM), the TGF-ß1-induced PML SUMOylation was reduced significantly with downregulation of the messenger RNA and protein for TGF-ß1 and Pin1. To verify the cellular function of PML by means of gain- or loss-of-function, the positive feedback signaling loop was enhanced or declined, meanwhile, TGF-ß-Smad signaling pathway was activated or weakened, respectively. In summary, we uncovered a novel reciprocal loop of TGF-ß1/PML SUMOylation/Pin1 leading to myocardial fibrosis.

PMLIV overexpression promotes TGF-ß-associated epithelial-mesenchymal transition and migration in MCF-7 cancer cells.

The epithelial-mesenchymal transition (EMT) is a key event associated with metastasis and dissemination in breast tumor pathogenesis. Promyelocytic leukemia (PML) gene produces several isoforms due to alternative splicing; however, the biological function of each specific isoform has yet to be identified. In this study, we report a previously unknown role for PMLIV, the most intensely studied nuclear isoform, in transforming growth factor-ß (TGF-ß) signaling-associated EMT and migration in breast cancer. This study demonstrates that PMLIV overexpression promotes a more aggressive mesenchymal phenotype and increases the migration of MCF-7 cancer cells. This event is associated with activation of the TGF-ß canonical signaling pathway through the induction of Smad2/3 phosphorylation and the translocation of phospho-Smad2/3 to the nucleus. In this study, we report a previously unknown role for PMLIV in TGF-ß signaling-induced regulation of breast cancer-associated EMT and migration. Targeting this pathway may be therapeutically beneficial.

PEP06 polypeptide 30 exerts antitumour effect in colorectal carcinoma via inhibiting epithelial-mesenchymal transition.

BACKGROUND AND PURPOSE: PEP06, a polypeptide modified from endostatin, was investigated for its antitumour effects on colorectal cancer (CRC) and the possible mechanisms of this antitumour activity were examined in in vitro and in vivo models. EXPERIMENTAL APPROACH: After PEP06 treatment, cell proliferation and migration assays were performed in CRC cells. Epithelial-mesenchymal transition (EMT) progression was determined by Western blotting, immunofluorescent staining and immunohistochemistry in vitro and in a residual xenograft model. MiRNAs regulated by PEP06 were identified by miRNA microarray and verified by in situ hybridization and quantitative real-time PCR. The interactions between PEP06 and integrin αvß3 were determined with Biacore SA biochips. The cellular function of miR-146b-5p was validated by gain-of-function and loss-of-function approaches. A mouse model of lung metastasis was used to determine the effect of PEP06 on metastatic growth. KEY RESULTS: PEP06 did not affect cell viability but reduced migration and EMT in SW620 and HCT116 cells. PEP06 significantly repressed the expression of miR-146b-5p in these two cell lines through binding to integrin αvß3. MiR-146b-5p was shown to increase EMT by targeting Smad4, and the miR-146b-5p-Smad4 cascade regulated EMT in CRC. PEP06 also suppressed CRC pulmonary metastasis, increased survival of mice and hampered residual tumour growth by inhibiting EMT through down-regulating miR-146b-5p. CONCLUSIONS AND IMPLICATIONS: PEP06 is a polypeptide that inhibits the growth and metastasis of colon cancer through its RGD motif binding to integrin αvß3, thereby down-regulating miR-146b-5p to inhibit EMT in vitro and in vivo. It might have potential as a therapeutic for CRC.

Pharmacological inhibition of SUMO-1 with ginkgolic acid alleviates cardiac fibrosis induced by myocardial infarction in mice.

BACKGROUND AND PURPOSE: Protein modification by small ubiquitin-like modifier (SUMO) plays a critical role in the pathogenesis of heart diseases. The present study was designed to determine whether ginkgolic acid (GA) as a SUMO-1 inhibitor exerts an inhibitory effect on cardiac fibrosis induced by myocardial infarction (MI). EXPERIMENTAL APPROACH: GA was delivered by osmotic pumps in MI mice. Masson staining, electron microscopy (EM) and echocardiography were used to assess cardiac fibrosis, ultrastructure and function. Expression of SUMO-1, PML, TGF-ß1 and Pin1 was measured with Western blot or Real-time PCR. Collagen content, cell viability and myofibroblast transformation were measured in neonatal mouse cardiac fibroblasts (NMCFs). Promyelocytic leukemia (PML) protein was over-expressed by plasmid transfection. KEY RESULTS: GA improved cardiac fibrosis and dysfunction, and decreased SUMO-1 expression in MI mice. GA (>20 µM) inhibited NMCF viability in a dose-dependent manner. Nontoxic GA (10 µM) restrained angiotensin II (Ang II)-induced myofibroblast transformation and collagen production. GA also inhibited expression of TGF-ß1 mRNA and protein in vitro and in vivo. GA suppressed PML SUMOylation and PML nuclear body (PML-NB) organization, and disrupted expression and recruitment of Pin1 (a positive regulator of TGF-ß1 mRNA), whereas over-expression of PML reversed that. CONCLUSIONS AND IMPLICATIONS: Inhibition of SUMO-1 by GA alleviated MI-induced heart dysfunction and fibrosis, and the SUMOylated PML/Pin1/TGF-ß1 pathway is crucial for GA-inhibited cardiac fibrosis.

Transforming Growth Factor-ß Receptor III is a Potential Regulator of Ischemia-Induced Cardiomyocyte Apoptosis.

BACKGROUND: Myocardial infarction (MI) is often accompanied by cardiomyocyte apoptosis, which decreases heart function and leads to an increased risk of heart failure. The aim of this study was to examine the effects of transforming growth factor-ß receptor III (TGFßR3) on cardiomyocyte apoptosis during MI. METHODS AND RESULTS: An MI mouse model was established by left anterior descending coronary artery ligation. Cell viability, apoptosis, TGFßR3, and mitogen-activated protein kinase signaling were assessed by methylthiazolyldiphenyl-tetrazolium bromide assay, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunofluorescence, electron microscopy, and Western blotting. Our results demonstrated that TGFßR3 expression in the border region of the heart was dynamically changed during MI. After stimulation with H2O2, TGFßR3 overexpression in cardiomyocytes led to increased cell apoptosis and activation of p38 signaling, whereas TGFßR3 knockdown had the opposite effect. ERK1/2 and JNK1/2 signaling was not altered by TGFßR3 modulation, and p38 inhibitor (SB203580) reduced the effect of TGFßR3 on apoptosis, suggesting that p38 has a nonredundant function in activating apoptosis. Consistent with the in vitro observations, cardiac TGFßR3 transgenic mice showed augmented cardiomyocyte apoptosis, enlarged infarct size, increased injury, and enhanced p38 signaling upon MI. Conversely, cardiac loss of function of TGFßR3 by adeno-associated viral vector serotype 9-TGFßR3 short hairpin RNA attenuated the effects of MI in mice. CONCLUSIONS: TGFßR3 promotes apoptosis of cardiomyocytes via a p38 pathway-associated mechanism, and loss of TGFßR3 reduces MI injury, which suggests that TGFßR3 may serve as a novel therapeutic target for MI.

Arsenic trioxide and angiotensin II have inhibitory effects on HERG protein expression: Evidence for the role of PML SUMOylation.

The human ether-a-go-go-related gene (HERG) channel is a novel target for the treatment of drug-induced long QT syndrome, which causes lethal cardiotoxicity. This study is designed to explore the possible role of PML SUMOylation and its associated nuclear bodies (NBs) in the regulation of HERG protein expression. Both arsenic trioxide (ATO) and angiotensin II (Ang II) were able to significantly reduce HERG protein expression, while also increasing PML SUMOylation and accelerating the formation of PML-NBs. Pre-exposure of cardiomyocytes to a SUMOylation chemical inhibitor, ginkgolic acid, or the silencing of UBC9 suppressed PML SUMOylation, subsequently preventing the downregulation of HERG induced by ATO or Ang II. Conversely, knockdown of RNF4 led to a remarkable increase in PML SUMOylation and the function of PML-NBs, further promoting ATO- or Ang II-induced HERG protein downregulation. Mechanistically, an increase in PML SUMOylation by ATO or Ang II dramatically enhanced the formation of PML and Pin1 complexes in PML-NBs, leading to the upregulation of TGF-ß1 protein, eventually inhibiting HERG expression through activation of protein kinase A. The present work uncovered a novel molecular mechanism underlying HERG protein expression and indicated that PML SUMOylation is a critical step in the development of drug-acquired arrhythmia.

Manipulating PML SUMOylation via Silencing UBC9 and RNF4 Regulates Cardiac Fibrosis.

The promyelocytic leukemia protein (PML) is essential in the assembly of dynamic subnuclear structures called PML nuclear bodies (PML-NBs), which are involved in regulating diverse cellular functions. However, the possibility of PML being involved in cardiac disease has not been examined. In mice undergoing transverse aortic constriction (TAC) and arsenic trioxide (ATO) injection, transforming growth factor ß1 (TGF-ß1) was upregulated along with dynamic alteration of PML SUMOylation. In cultured neonatal mouse cardiac fibroblasts (NMCFs), ATO, angiotensin II (Ang II), and fetal bovine serum (FBS) significantly triggered PML SUMOylation and the assembly of PML-NBs. Inhibition of SUMOylated PML by silencing UBC9, the unique SUMO E2-conjugating enzyme, reduced the development of cardiac fibrosis and partially improved cardiac function in TAC mice. In contrast, enhancing SUMOylated PML accumulation, by silencing RNF4, a poly-SUMO-specific E3 ubiquitin ligase, accelerated the induction of cardiac fibrosis and promoted cardiac function injury. PML colocalized with Pin1 (a positive regulator for TGF-ß1 mRNA expression in PML-NBs) and increased TGF-ß1 activity. These findings suggest that the UBC9/PML/RNF4 axis plays a critical role as an important SUMO pathway in cardiac fibrosis. Modulating the protein levels of the pathway provides an attractive therapeutic target for the treatment of cardiac fibrosis and heart failure.

Transient Receptor Potential Melastatin 4 (TRPM4) Contributes to High Salt Diet-Mediated Early-Stage Endothelial Injury.

BACKGROUND/AIMS: The present study investigated whether the transient receptor potential melastatin 4 (TRPM4) channel plays a role in high salt diet (HSD)-induced endothelial injuries. METHODS: Western blotting and immunofluorescence were used to examine TRPM4 expression in the mesenteric endothelium of Dahl salt-sensitive (SS) rats fed a HSD. The MTT, TUNEL, and transwell assays were used to evaluate the cell viability, cell apoptosis, and cell migration, respectively, of human umbilical vein endothelial cells (HUVECs). Enzyme-linked immunosorbent assays were used to determine the concentrations of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion protein 1 (VCAM-1), and E-selectin. Carboxy-H2DCFDA, a membrane-permeable reactive oxygen species (ROS)-sensitive fluorescent probe, was used to detect intracellular ROS levels. RESULTS: TRPM4 was mainly expressed near the plasma membrane of mesenteric artery endothelial cells, and its expression level increased in SS hypertensive rats fed a HSD. Its protein expression was significantly upregulated upon treatment with exogenous hydrogen peroxide (H2O2) and aldosterone in cultured HUVECs. Cell viability decreased upon treatment with both agents in a concentration-dependent manner, which could be partially reversed by 9-phenanthrol, a specific TRPM4 inhibitor. Exogenous H2O2 induced apoptosis, enhanced cell migration, and increased the release of adhesion molecules, including ICAM-1, VCAM-1, and E-selectin, all of which were significantly attenuated upon treatment with 9-phenanthrol. Aldosterone and H2O2 induced the accumulation of intracellular ROS, which was significantly inhibited by 9-phenanthrol, suggesting that oxidative stress is one of the mechanisms underlying aldosterone-induced endothelial injury. CONCLUSIONS: Given the fact that oxidative stress and high levels of circulating aldosterone are present in hypertensive patients, we suggest that the upregulation of TRPM4 in the vascular endothelium may be involved in endothelial injuries caused by these stimuli.

TRPP2 and TRPV4 form an EGF-activated calcium permeable channel at the apical membrane of renal collecting duct cells.

OBJECTIVE: Regulation of apical calcium entry is important for the function of principal cells of the collecting duct. However, the molecular identity and the regulators of the transporter/channel, which is responsible for apical calcium entry and what factors regulate the calcium conduction remain unclear. METHODS AND RESULTS: We report that endogenous TRPP2 and TRPV4 assemble to form a 23-pS divalent cation-permeable non-selective ion channel at the apical membrane of renal principal cells of the collecting duct. TRPP2\TRPV4 channel complex was identified by patch-clamp, immunofluorescence and co-immunprecipitation studies in both principal cells that either possess normal cilia (cilia (+)) or in which cilia are absent (cilia (-)). This channel has distinct biophysical and pharmacological and regulatory profiles compared to either TRPP2 or TRPV4 channels. The rate of occurrence detected by patch clamp was higher in cilia (-) compared to cilia (+) cells. In addition, shRNA knockdown of TRPP2 increased the prevalence of TRPV4 channel activity while knockdown of TRPV4 resulted in TRPP2 activity and knockdown of both proteins vastly decreased the 23-pS channel activity. Epidermal growth factor (EGF) stimulated TRPP2\TRPV4 channel through the EGF receptor (EGFR) tyrosine kinase-dependent signaling. With loss of cilia, apical EGF treatment resulted in 64-fold increase in channel activity in cilia (-) but not cilia (+) cells. In addition EGF increased cell proliferation in cilia (-) cell that was dependent upon TRPP2\TRPV4 channel mediated increase in intracellular calcium. CONCLUSION: We conclude that in the absence of cilia, an EGF activated TRPP2\TRPV4 channel may play an important role in increased cell proliferation and cystogenesis.

Maslinic acid induces apoptosis in salivary gland adenoid cystic carcinoma cells by Ca2+-evoked p38 signaling pathway.

Maslinic acid (MA) is a triterpenoid with a high concentration that exists in olives. This natural compound, which has shown multiple biological activities, was proved to be an anti-tumoral agent more recently. We have investigated the mechanisms of MA with regard to its inhibitory effects on the growth of salivary gland adenoid cystic carcinoma (ACC). We demonstrated that MA at 10-100 µM reduced cell viability in a dose-dependent manner, IC(50) of 43.68 µM, and 45.76 µM, respectively in cultured ACC-2 and ACC-M cells. Fifty micromolars of MA efficiently induced apoptosis as indicated by AO/EB staining, electronic microscopy, flow cytometry, and activation of caspase-3 activity. MA induced an elevation of [Ca(2+)](i) in a dose-dependent manner, and cell viability inhibition and cell apoptosis induced by MA were blocked by an intracellular Ca(2+) chelator, BAPTA-AM. The elevation of [Ca(2+)](i) induced by MA was blocked by EGTA or TRPV channel inhibitor suggesting TRPV channel involved in calcium influx induced by MA. MA also activated ERK and p38 MAPK in a time-dependent manner. MA induced cell apoptosis and activation of caspase-3 activity were reversed by SB203580, but not by PD98059, suggesting that the apoptosis induction of MA was via p38 MAPK, but not via ERK. Chelation of intracellular Ca(2+) with BAPTA reversed MA induced p38 MAPK phosphorylation, but SB203580 did not block MA-evoked elevation of [Ca(2+)](i), suggesting a Ca(2+)-evoked p38 MAPK signaling involved in MA-induced apoptosis in ACC cells. Taken together, in ACC cells, maslinic acid induced an increase in [Ca(2+)](i), which evoked p38 MAPK phosphorylation, subsequently activated caspase-3 leading to apoptosis.

PAF exerts a direct apoptotic effect on the rat H9c2 cardiomyocytes in Ca2+-dependent manner.

BACKGROUND: Previous studies suggested that platelet-activating factor (PAF) plays an important role in ischemic diseases. Apoptosis has been implicated in myocardial infarction-related cell death. The present study was designed to determine whether PAF could induce apoptosis in cardiac myocytes and the underlying mechanisms by which PAF causes apoptosis. METHODS: H9c2 cardiac myocytes were used to investigate the effect of PAF on intracellular calcium concentration, cell viability and cell apoptosis. Signaling pathway of caspase-3, cytochrome c and MAPK (ERK, JNK, p38) was determined during the PAF induced apoptosis. RESULTS: First, our results showed that treatment of H9c2 cardiomyocytes with PAF (0.2 to 20 microM) caused apoptosis in these cells and the apoptotic process was suppressed by either BN52021 (an antagonist of PAF receptor) or BAPTA/AM (an intracellular Ca2+ chelator), suggesting an involvement of PAF and its receptor mediated calcium-dependent signaling. Second, we found that activity of p38-MAPK (mitogen-activated protein kinase) and caspase-3 was elevated in the cells treated with PAF, without altering activity of ERK and JNK, and that PAF-induced enhancement of caspase-3 activity was attenuated by application of either BAPTA/AM or SB203580 (p38 inhibitor). Furthermore, PAF-induced apoptosis and release of cytochrome c from mitochondria was blunted by SB203580, and PAF-induced enhancement of p38 activity was also attenuated by BAPTA/AM. CONCLUSION: Our data implicate that a PAF and its receptor in triggering apoptosis occurs in cultured H9c2 cardiac myocytes via a calcium-dependent p38 MAPK activated cytochrome c/caspase-3 apoptosis signaling pathway.

Sulforaphane induces G2-M arrest and apoptosis in high metastasis cell line of salivary gland adenoid cystic carcinoma.

New chemotherapeutic strategy should be investigated to enhance clinical management in salivary gland adenoid cystic carcinoma (ACC). Recently, sulforaphane (SFN), as a natural compound from cruciferous vegetables exhibits a potent anti-cancer activity in various tumor cells, but remains uncertain in ACC cells. The present study examined whether SFN suppresses proliferation and in ACC cells, if so, the possible molecular targets would be further investigated. Cell survives, apoptosis, cell cycle progression and molecular targets were identified by multiple detecting techniques, including trypan blue dye exclusion assay, electron microscopy, AO/EB staining, flow cytometry and immunoblotting in human lung high metastasis cell line of salivary gland adenoid cystic carcinoma (ACC-M). The results showed that 5-20 microM SFN suppressed proliferation and induced apoptosis of ACC-M cells in dose- and time-dependent manners. Cell cycle analysis demonstrated treatment of ACC-M cells with 20 microM SFN resulted in G(2)/M cell cycle arrest, which was associated with a marked decline in protein levels of G(2)/M regulatory proteins including cyclin B1 and cyclin-dependent kinase 1 (Cdk1). In terms of apoptosis, SFN increased the expression of Bax and decreased the level of Bcl-2 and subsequently triggered release of cytochrome c from mitochondria and activation of caspase-3, but Fas level and caspase-8 activity remained unchanged at all time points. Furthermore, levels of nuclear factor-kappaB (NF-kappaB) p65 in both of the cytoplasm and the nucleus have also been markedly suppressed by SFN in a time-dependent manner. Taken together, these results suggest SFN inhibits cell growth via inducing G(2)/M cell arrest and apoptosis in ACC-M cells. These events have been associated with SFN-regulated multiple targets involved in ACC-M cell proliferation. The present study provides an evidence for testing SFN efficacy in vivo and warranting future investigations to exam the clinical potential of SFN in ACC chemotherapy.

Choline-modulated arsenic trioxide-induced prolongation of cardiac repolarization in Guinea pig.

Arsenic trioxide (As(2)O(3)) has been found to be effective for relapsed or refractory acute promyelocytic leukaemia, but its clinical use is burdened by QT prolongation, Torsade de pointes tachycardias, and sudden cardiac death. The aim of the present study was to elucidate the ionic mechanisms of As(2)O(3)-induced abnormalities of cardiac electrophysiology and the therapeutic action of choline on As(2)O(3)-caused QT prolongation in guinea pig. Intravenous administration of As(2)O(3) prolonged the QT interval in a dose- and time-dependent manner in guinea pig hearts, and the QT prolongation could be modulated by choline. By using whole-cell patch clamp technique and confocal laser scanning microscopy, we found that As(2)O(3) significantly lengthened action potential duration measured at 50 and 90% of repolarization, enhanced L-type calcium currents (I(Ca-L)), inhibited delayed rectifier potassium currents (I(K)), and increased intracellular calcium concentration ([Ca(2+)](i)) in guinea pig ventricular myocytes. Choline corrected As(2)O(3)-mediated alterations of action potential duration, I(Ca-L) and [Ca(2+)](i), but had no effect on the I(K) inhibition. As(2)O(3) markedly disturbed the normal equilibrium of transmembrane currents (increasing I(Ca-L) and suppressing I(K)) in guinea pig cardiomyocyte, and induced prolongation of action potential duration, further degenerated into QT prolongation. Choline normalized QT interval abnormality and corrected lengthened action potential duration by inhibiting the elevated I(Ca-L) and [Ca(2+)](i) in ventricular myocytes during As(2)O(3) application.

Increasing Intracellular calcium of guinea pig ventricular myocytes induced by platelet activating factor through IP3 pathway.

We used Fluo-3/AM to examine the effect of platelet-activating factor on the intracellular Ca2+([Ca2+]i) levels in isolated myocytes of guinea pig ventricle. Myocytes were isolated with Langendorff perfusion technique and were challenged with platelet-activating factor. Addition of platelet-activating factor (1 pM to 10 nM) significantly increased the [Ca2+]i in the presence and absence of extracellular Ca2+. The notion that increases in intracellular Ca2+ induced by platelet-activating factor is the result of stimulation of intracellular Ca2+ pool rather than increasing Ca2+ influx was further supported by the whole cell patch-clamp experiments in which the platelet-activating factor did not alter the activity of L-type of Ca2+ channels (I(Ca-L)). Treatment of myocytes with ryanodine failed to abolish the stimulatory effect of platelet-activating factor on [Ca2+]i. In contrast, inhibition of IP3-sensitive Ca2+ release pool with 2-aminoethoxydiphenyl borate (2-APB) blocked the effect of platelet-activating factor. We conclude that the platelet-activating factor-induced increase in intracellular Ca2+ is mediated by stimulation of IP3 receptor but not by stimulation of I(Ca-L) and ryanodine-sensitive receptor.

[Effect of yeast RNA on physical functions, morphology of hepatic cells and brain neurons in aged rats].

OBJECTIVE: To study the effect of exogenous nucleic acid on physical functions, morphology of hepatic cells and brain neurons in aged rats. METHODS: Thirty two aged Wistar rats (20 month-old) were divided randomly into four groups (one aged control group and three aged experimental groups) and eight young rats (3 month-old) was set as young control group. Control groups were fed on standard chow and experimental groups were fed on standard chow supplemented with 93.75 mg/kg (high-dosage group), 46.88 mg/kg (middle-dosage group) and 9.38 mg/kg (low-dosage group) of yeast RNA respectively. SOD, MDA, HDL, sex hormone and growth hormone were determined at the end of a 4-week observation. The microcosmic images of the hepatic cells and brain neurons using the image-pro plus (V.4.0) were also observed. RESULTS: SOD, serum HDL and growth hormone levels in the high dosage group were significantly higher (P < 0.05) than that in the aged control group, and the levels were not different from that in the young control group. MDA level of all yeast RNA supplemented groups was significantly lower than that of aged control group (P < 0.05) and that was not different from the young control group. Serum testosterone of the high and middle dosage groups reached the level of young control group, and that was much higher than the aged control and low dosage group (P < 0.05). Estradiol levels among the aged rats were not different, and those were much lower than the young control group (P < 0.05). Much more number of brain neurons were observed in the high-dose group than other aged rats (P < 0.05). Brain neurons, hepatic cells and karyons in the high-dose group were bigger than that in other aged rats (P < 0.05). CONCLUSION: Exogenous yeast RNA might play an important role in physical functions, the morphology of brain neurons and hepatic cells in natural aged rats. There might have a dose-effect relationship in the process.

[Screening genes of differential expression in BALB/C mice thymus: a pilot study of effect of salmon milt DNA (SMD) on age-related involutions].

OBJECTIVE: To investigate the effect and its mechanism of salmon milt DNA (SMD) on age-related involutions in mouse thymus. METHODS: Female BALB/C mice aged 10 months were divided randomly into three groups according to their weights. They were high dosage group (333.33 mg.kg(-1).b.w.d(-1)), low dosage group (166.67 mg.kg(-1).b.w.d(-1)) and control group (0 mg.kg(-1).b.w.d(-1)). After five weeks, their thymus indexes were measured and the thymocytes were counted and the thymus cortex thicknesses were also measured using Image-Pro Plus (version. 4.0) software in the thymus section. All the data were analyzed by SAS statistic software. Microarray technique was applied to screen the gene fragments, which were differentially expressed between the high dosage group and the control group, together with RT-PCR to further confirm some of them. RESULTS: No significant differences of the variables including body weight, thymus weight and thymus indexes among the three groups were found. The thymocytes quantities of thymus cortex and medulla in the high dosage group were significantly higher than those of the control group (P < 0.01 and P < 0.05, respectively). The thymus cortex thicknesses of both SMD supplement groups were significantly higher than that of the control group (P < 0.01 and P < 0.05 respectively). 112 differently expressed gene fragments were isolated. Furthermore, we found the fragments with the logged number of U23789, X80232 and Aw209102 were highly expressed in the high dosage group when RT-PCR technique was used. CONCLUSIONS: SMD may reverse the age-related involutions in mouse thymus via up-regulation the expression of proliferation related genes and via up-regulation the expression of development and differentiation related genes simultaneously.