Topical Clonidine Accelerates Cutaneous Wound Healing in Diabetic Rats by Regulating the Expression of Related Cytokine Signaling.

Based on the analgesic and anti-inflammatory effects of clonidine in previous studies, we hypothesized that clonidine could accelerate wound healing in rats by regulating the expression of related cytokines. In this study, the wound healing effect of clonidine was evaluated using an excision wound model in diabetic rats and a HaCaT cell model. The wounds were treated daily with topical clonidine. The results analyzed by ImageJ2 software show that the wounds of the rats that were treated with 15 ng/mL clonidine recovered faster, and the wound size was also significantly reduced compared to the control group. Western blot assays determined that clonidine induced an increase in the expression of vascular growth factors, namely, Ang-1, Ang-2, and VEGF. Moreover, clonidine demonstrated a rescuing effect on JAK2 within the JAK/STAT pathway by inhibiting SOCS3 expression, leading to decreased SOCS3 levels and increased expression of JAK2 and phospho-STAT3. Histopathological analysis revealed that clonidine promoted complete epithelial repair and minimized inflammation in skin tissue. Additionally, clonidine stimulated HaCaT cell proliferation in vitro and enhanced cellular energy levels in the presence of AGEs. In conclusion, clonidine promoted vascular growth and wound healing by stimulating the expression of cytokines that are beneficial for wound healing.

Reduction of blood pressure elevation by losartan in spontaneously hypertensive rats through suppression of LARG expression in vascular smooth muscle cells.

BACKGROUND/PURPOSE: This study sought to elucidate the mechanism by which losartan inhibits blood pressure (BP) elevation in spontaneously hypertensive rats (SHRs). METHODS: Four-week-old Wistar-Kyoto (WKY) rats and SHRs were either treated with losartan (20 mg/kg/day) for 8 weeks or served as untreated controls. BP was measured by the tail-cuff method. At 12 weeks, isometric contraction of the aortic rings of the rats was evaluated with a force transducer and recorder. The mRNA and protein levels of the target Rho guanine nucleotide exchange factors (RhoGEFs), and the extent of myosin phosphatase target subunit 1 (MYPT-1) phosphorylation in the aorta, were determined using quantitative real-time polymerase chain reaction (qPCR) assay and Western blot analysis. RESULTS: The BP of the four-week-old SHRs did not differ from that of the age-matched WKY rats, whereas the BP of the twelve-week-old control group SHRs was higher than that of the control group WKY rats. Losartan treatment, however, inhibited BP elevation in both rat strains, doing so to a greater extent in the treatment group SHRs. The contractile force in response to angiotensin II of the aortic rings from the SHRs treated with losartan was significantly lower than that of the aortic rings from the non-treated SHRs. The protein expression of leukemia-associated RhoGEF (LARG) was significantly higher in the non-treated SHRs compared to the non-treated WKY rats. CONCLUSION: The study results showed that the reduction of BP elevation by losartan in SHRs occurs through the suppression of LARG expression and MYPT-1 phosphorylation in vascular smooth muscle cells.

Single allele Lmbrd1 knockout results in cardiac hypertrophy.

BACKGROUND/PURPOSE: LMBD1 protein, a type IV-B plasma membrane protein possessing nine putative trans-membrane domains, was previously demonstrated at cellular level to play a critical part in the signaling cascade of insulin receptor through its involvement in regulating clathrin-mediated endocytosis. However, at physiological level, the significance of LMBD1 protein in cardiac development remains unclear. METHODS: To understand the role of Lmbrd1 gene involved in the cardiac function, heterozygous knockout mice were used as an animal model system. The pathological outcomes were analyzed by micro-positron emission tomography, ECG acquisition, cardiac ultrasound, and immunohistochemistry. RESULTS: By studying the heterozygous knockout of Lmbrd1 (Lmbrd1+/-), we discovered that lack of Lmbrd1 not only resulted in the increase of cardiac-glucose uptake, pathological consequences were also observed. Here, we have distinguished that Lmbrd1+/- is sufficient in causing cardiac diseases through a pathway independent of the recessive vitamin B12 cblF cobalamin transport defect. Lmbrd1+/- mice exhibited an increase in myocardial glucose uptake and insulin receptor signaling that is insensitive to the administration of additional insulin. Pathological symptoms such as cardiac hypertrophy, ventricular tissue fibrosis, along with the increase of heart rate and cardiac muscle contractility were observed. As Lmbrd1+/- mice aged, the decrease in ejection fraction and fraction shortening showed signs of ventricular function deterioration. CONCLUSION: The results suggested that Lmbrd1 gene not only plays a significant role in mediating the energy homeostasis in cardiac tissue, it may also be a key factor in the regulation of cardiac function in mice.

NRIP is newly identified as a Z-disc protein, activating calmodulin signaling for skeletal muscle contraction and regeneration.

Nuclear receptor interaction protein (NRIP, also known as DCAF6 and IQWD1) is a Ca(2+)-dependent calmodulin-binding protein. In this study, we newly identify NRIP as a Z-disc protein in skeletal muscle. NRIP-knockout mice were generated and found to have reduced muscle strength, susceptibility to fatigue and impaired adaptive exercise performance. The mechanisms of NRIP-regulated muscle contraction depend on NRIP being downstream of Ca(2+) signaling, where it stimulates activation of both 'calcineurin-nuclear factor of activated T-cells, cytoplasmic 1' (CaN-NFATc1; also known as NFATC1) and calmodulin-dependent protein kinase II (CaMKII) through interaction with calmodulin (CaM), resulting in the induction of mitochondrial activity and the expression of genes encoding the slow class of myosin, and in the regulation of Ca(2+) homeostasis through the internal Ca(2+) stores of the sarcoplasmic reticulum. Moreover, NRIP-knockout mice have a delayed regenerative capacity. The amount of NRIP can be enhanced after muscle injury and is responsible for muscle regeneration, which is associated with the increased expression of myogenin, desmin and embryonic myosin heavy chain during myogenesis, as well as for myotube formation. In conclusion, NRIP is a novel Z-disc protein that is important for skeletal muscle strength and regenerative capacity.

Increased LDL electronegativity in chronic kidney disease disrupts calcium homeostasis resulting in cardiac dysfunction.

Chronic kidney disease (CKD), an independent risk factor for cardiovascular disease, is associated with abnormal lipoprotein metabolism. We examined whether electronegative low-density lipoprotein (LDL) is mechanistically linked to cardiac dysfunction in patients with early CKD. We compared echocardiographic parameters between patients with stage 2 CKD (n = 88) and normal controls (n = 89) and found that impaired relaxation was more common in CKD patients. Reduction in estimated glomerular filtration rate was an independent predictor of left ventricular relaxation dysfunction. We then examined cardiac function in a rat model of early CKD induced by unilateral nephrectomy (UNx) by analyzing pressure-volume loop data. The time constant of isovolumic pressure decay was longer and the maximal velocity of pressure fall was slower in UNx rats than in controls. When we investigated the mechanisms underlying relaxation dysfunction, we found that LDL from CKD patients and UNx rats was more electronegative than LDL from their respective controls and that LDL from UNx rats induced intracellular calcium overload in H9c2 cardiomyocytes in vitro. Furthermore, chronic administration of electronegative LDL, which signals through lectin-like oxidized LDL receptor-1 (LOX-1), induced relaxation dysfunction in wild-type but not LOX-1(-/-) mice. In in vitro and in vivo experiments, impaired cardiac relaxation was associated with increased calcium transient resulting from nitric oxide (NO)-dependent nitrosylation of SERCA2a due to increases in inducible NO synthase expression and endothelial NO synthase uncoupling. In conclusion, LDL becomes more electronegative in early CKD. This change disrupts SERCA2a-regulated calcium homeostasis, which may be the mechanism underlying cardiorenal syndrome.

5-hydroxytryptamine has an endothelium-derived hyperpolarizing factor-like effect on coronary flow in isolated rat hearts.

BACKGROUND: 5-hydroxytryptamine (5-HT)-induced coronary artery responses have both vasoconstriction and vasorelaxation components. The vasoconstrictive effects of 5-HT have been well studied while the mechanism(s) of how 5-HT causes relaxation of coronary arteries has been less investigated. In isolated rat hearts, 5-HT-induced coronary flow increases are partially resistant to the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester (L-NAME) and are blocked by 5-HT7 receptor antagonists. In the present study, we investigated the role of 5-HT7 receptor in 5-HT-induced coronary flow increases in isolated rat hearts in the absence of L-NAME, and we also evaluated the involvement of endothelium-derived hyperpolarizing factor (EDHF) in 5-HT-induced coronary flow increases in L-NAME-treated hearts with the inhibitors of arachidonic acid metabolism and the blockers of Ca(2+)-activated K(+) channels. RESULTS: In isolated rat hearts, 5-HT and the 5-HT7 receptor agonist 5-carboxamidotryptamine induced coronary flow increases, and both of these effects were blocked by the selective 5-HT7 receptor antagonist SB269970; in SB269970-treated hearts, 5-HT induced coronary flow decreases, which effect was blocked by the 5-HT2A receptor blocker R96544. In L-NAME-treated hearts, 5-HT-induced coronary flow increases were blocked by the phospholipase A2 inhibitor quinacrine and the cytochrome P450 inhibitor SKF525A, but were not inhibited by the cyclooxygenase inhibitor indomethacin. As to the effects of the Ca(2+)-activated K(+) channel blockers, 5-HT-induced coronary flow increases in L-NAME-treated hearts were inhibited by TRAM-34 (intermediate-conductance Ca(2+)-activated K(+) channel blocker) and UCL1684 (small-conductance Ca(2+)-activated K(+) channel blocker), but effects of the large-conductance Ca(2+)-activated K(+) channel blockers on 5-HT-induced coronary flow increases were various: penitrem A and paxilline did not significantly affect 5-HT-induced coronary flow responses while tetraethylammonium suppressed the coronary flow increases elicited by 5-HT. CONCLUSION: In the present study, we found that 5-HT-induced coronary flow increases are mediated by the activation of 5-HT7 receptor in rat hearts in the absence of L-NAME. Metabolites of cytochrome P450s, small-conductance Ca(2+)-activated K(+) channel, and intermediate-conductance Ca(2+)-activated K(+) channel are involved in 5-HT-induced coronary flow increases in L-NAME-treated hearts, which resemble the mechanisms of EDHF-induced vasorelaxation. The role of large-conductance Ca(2+)-activated K(+) channel in 5-HT-induced coronary flow increases in L-NAME-treated hearts needs further investigation.

Pyrrolidinyl caffeamide against ischemia/reperfusion injury in cardiomyocytes through AMPK/AKT pathways.

BACKGROUND: Coronary heart disease is a leading cause of death in the world and therapy to reduce injury is still needed. The uncoupling of glycolysis and glucose oxidation induces lactate accumulation during myocardial ischemia/reperfusion (I/R) injury. Cell death occurs and finally leads to myocardial infarction. Caffeic acid, one of the major phenolic constituents in nature, acts as an antioxidant. Pyrrolidinyl caffeamide (PLCA), a new derivative of caffeic acid, was synthesized by our team. We aimed to investigate the effect of PLCA on hypoxia/reoxygenation (H/R) in neonatal rat ventricular myocytes (NRVM) and on myocardial I/R in rats. RESULTS: Cardiomyocytes were isolated and subjected to 6 h hypoxia followed by 18 h reperfusion. PLCA (0.1 to 3 µM) and metformin (30 µM) were added before hypoxia was initiated. PLCA at 1 µM and metformin at 30 µM exerted similar effects on the improvement of cell viability and the alleviation of cell apoptosis in NRVM after H/R. PLCA promoted p-AMPK, p-AKT, and GLUT4 upregulation to induce a cardioprotective effect in both cell and animal model. The accumulation of cardiac lactate was attenuated by PLCA during myocardial I/R, and infarct size was smaller in rats treated with PLCA (1 mg/kg) than in those treated with caffeic acid (1 mg/kg). CONCLUSIONS: AMPK and AKT are synergistically activated by PLCA, which lead facilities glucose utilization, thereby attenuating lactate accumulation and cell death. The cardioprotective dose of PLCA was lower than those of metformin and caffeic acid. We provide a new insight into this potential drug for the treatment of myocardial I/R injury.

Caffeic acid ethanolamide prevents cardiac dysfunction through sirtuin dependent cardiac bioenergetics preservation.

BACKGROUND: Cardiac oxidative stress, bioenergetics and catecholamine play major roles in heart failure progression. However, the relationships between these three dominant heart failure factors are not fully elucidated. Caffeic acid ethanolamide (CAEA), a synthesized derivative from caffeic acid that exerted antioxidative properties, was thus applied in this study to explore its effects on the pathogenesis of heart failure. RESULTS: In vitro studies in HL-1 cells exposed to isoproterenol showed an increase in cellular and mitochondria oxidative stress. Two-week isoproterenol injections into mice resulted in ventricular hypertrophy, myocardial fibrosis, elevated lipid peroxidation, cardiac adenosine triphosphate and left ventricular ejection fraction decline, suggesting oxidative stress and bioenergetics changes in catecholamine-induced heart failure. CAEA restored oxygen consumption rates and adenosine triphosphate contents. In addition, CAEA alleviated isoproterenol-induced cardiac remodeling, cardiac oxidative stress, cardiac bioenergetics and function insufficiency in mice. CAEA treatment recovered sirtuin 1 and sirtuin 3 activity, and attenuated the changes of proteins, including manganese superoxide dismutase and hypoxia-inducible factor 1-α, which are the most likely mechanisms responsible for the alleviation of isoproterenol-caused cardiac injury CONCLUSION: CAEA prevents catecholamine-induced cardiac damage and is therefore a possible new therapeutic approach for preventing heart failure progression.

Caffeic acid phenethyl amide ameliorates ischemia/reperfusion injury and cardiac dysfunction in streptozotocin-induced diabetic rats.

BACKGROUND: Caffeic acid phenethyl ester (CAPE) has been shown to protect the heart against ischemia/reperfusion (I/R) injury by various mechanisms including its antioxidant effect. In this study, we evaluated the protective effects of a CAPE analog with more structural stability in plasma, caffeic acid phenethyl amide (CAPA), on I/R injury in streptozotocin (STZ)-induced type 1 diabetic rats. METHODS: Type 1 diabetes mellitus was induced in Sprague-Dawley rats by a single intravenous injection of 60 mg/kg STZ. To produce the I/R injury, the left anterior descending coronary artery was occluded for 45 minutes, followed by 2 hours of reperfusion. CAPA was pretreated intraperitoneally 30 minutes before reperfusion. An analog devoid of the antioxidant property of CAPA, dimethoxyl CAPA (dmCAPA), and a nitric oxide synthase (NOS) inhibitor (Nω-nitro-l-arginine methyl ester [l-NAME]) were used to evaluate the mechanism involved in the reduction of the infarct size following CAPA-treatment. Finally, the cardioprotective effect of chronic treatment of CAPA was analyzed in diabetic rats. RESULTS: Compared to the control group, CAPA administration (3 and 15 mg/kg) significantly reduced the myocardial infarct size after I/R, while dmCAPA (15 mg/kg) had no cardioprotective effect. Interestingly, pretreatment with a NOS inhibitor, (L-NAME, 3 mg/kg) eliminated the effect of CAPA on myocardial infarction. Additionally, a 4-week CAPA treatment (1 mg/kg, orally, once daily) started 4 weeks after STZ-induction could effectively decrease the infarct size and ameliorate the cardiac dysfunction by pressure-volume loop analysis in STZ-induced diabetic animals. CONCLUSIONS: CAPA, which is structurally similar to CAPE, exerts cardioprotective activity in I/R injury through its antioxidant property and by preserving nitric oxide levels. On the other hand, chronic CAPA treatment could also ameliorate cardiac dysfunction in diabetic animals.

Gender disparity in LDL-induced cardiovascular damage and the protective role of estrogens against electronegative LDL.

BACKGROUND: Increased levels of the most electronegative type of LDL, L5, have been observed in the plasma of patients with metabolic syndrome (MetS) and ST-segment elevation myocardial infarction and can induce endothelial dysfunction. Because men have a higher predisposition to developing coronary artery disease than do premenopausal women, we hypothesized that LDL electronegativity is increased in men and promotes endothelial damage. METHODS: L5 levels were compared between middle-aged men and age-matched, premenopausal women with or without MetS. We further studied the effects of gender-influenced LDL electronegativity on aortic cellular senescence and DNA damage in leptin receptor-deficient (db/db) mice by using senescence-associated-ß-galactosidase and γH2AX staining, respectively. We also studied the protective effects of 17ß-estradiol and genistein against electronegative LDL-induced senescence in cultured bovine aortic endothelial cells (BAECs). RESULTS: L5 levels were higher in MetS patients than in healthy subjects (P < 0.001), particularly in men (P = 0.001). LDL isolated from male db/db mice was more electronegative than that from male or female wild-type mice. In addition, LDL from male db/db mice contained abundantly more apolipoprotein CIII and induced more BAEC senescence than did female db/db or wild-type LDL. In the aortas of db/db mice but not wild-type mice, we observed cellular senescence and DNA damage, and the effect was more significant in male than in female db/db mice. Pretreatment with 17ß-estradiol or genistein inhibited BAEC senescence induced by male or female db/db LDL and downregulated the expression of lectin-like oxidized LDL receptor-1 and tumor necrosis factor-alpha protein. CONCLUSION: The gender dichotomy of LDL-induced cardiovascular damage may underlie the increased propensity to coronary artery disease in men.

Caffeic acid phenethyl amide improves glucose homeostasis and attenuates the progression of vascular dysfunction in Streptozotocin-induced diabetic rats.

BACKGROUND: Glucose intolerance and cardiovascular complications are major symptoms in patients with diabetes. Many therapies have proven beneficial in treating diabetes in animals by protecting the cardiovascular system and increasing glucose utilization. In this study, we evaluated the effects of caffeic acid phenethyl amide (CAPA) on glucose homeostasis and vascular function in streptozotocin (STZ)-induced type 1 diabetic rats. METHODS: Diabetes (blood glucose levels > 350 mg/dL), was induced in Wistar rats by a single intravenous injection of 60 mg/kg STZ. Hypoglycemic effects were then assessed in normal and type 1 diabetic rats. In addition, coronary blood flow in Langendorff-perfused hearts was evaluated in the presence or absence of nitric oxide synthase (NOS) inhibitor. The thoracic aorta was used to measure vascular response to phenylephrine. Finally, the effect of chronic treatment of CAPA and insulin on coronary artery flow and vascular response to phenylephrine were analyzed in diabetic rats. RESULTS: Oral administration of 0.1 mg/kg CAPA decreased plasma glucose in normal (32.9 ± 2.3% decrease, P < 0.05) and diabetic rats (11.8 ± 5.5% decrease, P < 0.05). In normal and diabetic rat hearts, 1-10 µM CAPA increased coronary flow rate, and this increase was abolished by 10 µM NOS inhibitor. In the thoracic aorta, the concentration/response curve of phenylephrine was right-shifted by administration of 100 µM CAPA. Coronary flow rate was reduced to 7.2 ± 0.2 mL/min at 8 weeks after STZ-induction. However, 4 weeks of treatment with CAPA (3 mg/kg, intraperitoneal, twice daily) started at 4 weeks after STZ induction increased flow rate to 11.2 ± 0.5 mL/min (P < 0.05). In addition, the contractile response induced by 1 µM phenylephrine increased from 6.8 ± 0.6 mN to 11.4 ± 0.4 mN (P < 0.05) and 14.9 ± 1.4 mN (P < 0.05) by insulin (1 IU/kg, intraperitoneal) or CAPA treatment, respectively. CONCLUSIONS: CAPA induced hypoglycemic activity, increased coronary blood flow and vascular response to phenylephrine in type 1 diabetic rats. The increase in coronary blood flow may result from endothelial NOS activation. However, the detailed cellular mechanisms need to be further evaluated.

P2X7 receptor activation contributes to an initial upstream mechanism of lipopolysaccharide-induced vascular dysfunction.

Pro-inflammatory cytokines, chemokines and ROS (reactive oxygen species) are excessively produced in endotoxaemia. However, attempting to inhibit all of these inflammatory signalling pathways at the same time in order to prevent endotoxaemia is difficult. In a previous study we observed that activation of P2X7 receptors elicited the release of IL (interleukin)-1ß from LPS (lipopolysaccharide)-incubated vessels. In the present study, we hypothesize that P2X7 receptor activation is the initial event leading to vascular dysfunction following LPS treatment. LPS-induced decreases in MAP (mean arterial pressure) and pressor responses to NE (noradrenaline) were attenuated in P2X7KO (P2X7-knockout) mice. Hyporeactivity in response to PE (phenylephrine) in isolated mesenteric arteries by LPS treatment was also observed in C57BL/6 [WT (wild-type)] mice, which was prevented by IL1ra (IL-1 receptor antagonist), L-NAME (N(G)-nitro-L-arginine methyl ester) and indomethacin and in P2X7KO mice. In addition, treatment with IL1ra plus L-NAME produced an additive inhibition of LPS-induced vascular hyporeactivity, suggesting different signalling pathways between IL-1ß and NOS (NO synthase). LPS-induced plasma levels of IL-1ß, TNFα (tumour necrosis factor α), IL-10, vascular eNOS (endothelial NOS) and COX2 (cyclo-oxygenase 2) protein expression, as determined by ELISA and Western blot, observed in WT mice were inhibited by IL1ra and in P2X7KO mice. These results suggest that P2X7 receptor activation involves an initial upstream mechanism of LPS-induced vascular dysfunction, which is associated with IL-1ß-mediated eNOS, COX2 activation and TNFα release.

Semisynthesis and myocardial activity of thaliporphine N-homologues.

The N-homologues and optical isomers of thaliporphine (5a), a potent antiarrhythmic agent, were prepared starting from laurolitsine (1), an abundant aporphine present in Phoebe formosana. Treating N-propylnorglaucine with 90% H2SO4 yielded one additional product, an 11-sulfonyl-1,11-anhydroaporphine. Reaction of N-formylnorglaucine (3a) with 90% H2SO4, however, yielded the 9-sulfonyl-seco product as a major product. Treatment of 3a with 98% H2SO4 yielded pancordine (10), which, upon catalytic hydrogenation, yielded (±)-wilsonirine. (1)H NMR spectroscopic analysis was applied successfully to monitor the optical purity of the crystalline salt while undertaking optical resolution. Thaliporphine (5a) was demonstrated to possess better positive inotropic and less negative chronotropic effects than the left-hand optical isomer and showed the best activity on rat cardiac tissue among the N-homologues prepared.

Coexisting mutations/polymorphisms of the long QT syndrome genes in patients with repaired Tetralogy of Fallot are associated with the risks of life-threatening events.

Coexisting long QT gene mutations/polymorphisms in Tetralogy of Fallot (TOF) patients may aggravate the repolarization abnormality from cardiac repair. We investigated the impact of these genes on the risk of life-threatening events. Genetic variants of the three common long QT genes were identified from patients with repaired TOF. Life-threatening events were defined as sudden cardiac death and hemodynamic unstable ventricular arrhythmia. Biophysical characterization of the alleles of the genetic variants was performed using a whole-cell voltage clamp with expression in Xenopus oocytes. A total of 84 patients (56.0 % male with 1,215 patients-year follow-up) were enrolled. Six rare variants and six non-synonymous single nucleotide polymorphisms (SNPs) were found in 40 (47.6 %) patients. Life-threatening events occurred in five patients; four received implantable cardioverter defibrillator and one died of sudden cardiac death. Life-threatening events occurred more often in those with genetic variants than those without (5/40 vs. 0/44, P = 0.021); particularly, the hERG or SCN5A gene mutations/polymorphisms (2/5 vs. 3/79, P = 0.027 and 5/27 vs. 0/57, P = 0.003, respectively). Among the five patients with life-threatening events, three had compound variants (hERG p.M645R/SCN5A p.R1193Q, hERG p.K897T/SCN5A p.H558R, and KVLQT1 p.G645S/SCN5A p.P1090L), that also increased the risk of events. Their QTc and JTc were all prolonged. Functional study of the novel variant (hERG gene p.M645R) from patients with life-threatening events revealed a dominant negative effect. In conclusion, in repaired TOF patients, coexisting long QT mutations/polymorphisms might have additive effects on the repolarization abnormality from surgery and thereby increase the risks of life-threatening events.

Hypoglycemic diterpenoids from Tinospora crispa.

Three new diterpenoids, 2-O-lactoylborapetoside B (1), 6'-O-lactoylborapetoside B (2), and tinocrispol A (3), and nine known diterpenoids (4-12) were isolated from an EtOH extract of Tinospora crispa vines. Their structures were elucidated by spectroscopic analyses. The C-6 glucosyloxy group in borapetoside C (6) was revised to be α-oriented. The in vivo hypoglycemic activities of the major components, borapetosides A-C (4-6), were examined. Intraperitoneal injection of 4 and 6 (5 mg/kg) showed significant lowering of plasma glucose levels in normal and streptozotocin-induced type 1 diabetic mice. Borapetoside C increased glucose utilization in peripheral tissues and reduced hepatic gluconeogenesis, accounting for the hypoglycemic effect.

Caffeic Acid Phenylethyl Amide Protects against the Metabolic Consequences in Diabetes Mellitus Induced by Diet and Streptozocin.

Caffeic acid phenyl ester is distributed wildly in nature and has antidiabetic and cardiovascular protective effects. However, rapid decomposition by esterase leads to its low bioavailability in vivo. In this study, chronic metabolic and cardiovascular effects of oral caffeic acid phenylethyl amide, whose structure is similar to caffeic acid phenyl ester and resveratrol, were investigated in ICR mice. We found that caffeic acid phenylethyl amide protected against diet or streptozocin-induced metabolic changes increased coronary flow and decreased infarct size after global ischemia-reperfusion in Langendorff perfused heart. Further study indicated that at least two pathways might be involved in such beneficial effects: the induction of the antioxidant protein MnSOD and the decrease of the proinflammatory cytokine TNFα and NFκB in the liver. However, the detailed mechanisms of caffeic acid phenylethyl amide need further studies. In summary, this study demonstrated the protective potential of chronic treatment of caffeic acid phenylethyl amide against the metabolic consequences in diabetes mellitus.

Cardiac glycosides from Antiaris toxicaria with potent cardiotonic activity.

An ethanolic extract of Antiaris toxicaria trunk bark showed potent in vitro cardiotonic effect on isolated guinea pig atria. Bioassay-guided fractionation of the extract led to identification of nine new cardiac glycosides (1-9, named antiarosides A-I), antiarotoxinin A (10), and 18 known compounds. Their structures were established using MS and NMR spectroscopic studies, including homonuclear and heteronuclear correlation experiments. The ability of these cardiotonic compounds to produce positive inotropic action and their safety indexes were examined in comparison with those of ouabain, a classical inhibitor of Na(+)/K(+)-ATPase. Malayoside (23) was nearly equipotent and had a similar safety index to ouabain in guinea pig atria. However, the maximal positive inotropic effect and safety index of 23 in papillary muscle were better than those of ouabain. An electrophysiological recording showed that 23 inhibited the sodium pump current in a concentration-dependent manner.

Soluble Dipeptidyl Peptidase-4 Induces Fibroblast Activation Through Proteinase-Activated Receptor-2.

Fibroblasts are the chief secretory cells of the extracellular matrix (ECM) responsible for basal deposition and degradation of the ECM under normal conditions. During stress, fibroblasts undergo continuous activation, which is defined as the differentiation of fibroblasts into myofibroblasts, a cell type with an elevated capacity for secreting ECM proteins. Dipeptidyl peptidase-4 (DPP4) is a ubiquitously expressed transmembrane glycoprotein and exerts effects that are both dependent and independent of its enzymatic activity. DPP4 has been demonstrated to define fibroblast populations in human skin biopsies of systemic sclerosis. Shedding of DPP4 from different tissues into the circulation appears to be involved in the pathogenesis of the diseases. The mechanism underlying soluble DPP4-induced dermal fibrosis has not been clearly determined. The effects of DPP4 on murine 3T3 fibroblasts and human dermal fibroblasts were evaluated by measuring the expression of fibrotic proteins, such as α-SMA and collagen. Soluble DPP4 stimulated the activation of fibroblasts in a dose-dependent manner by activating nuclear factor-kappa B (NF-κB) and suppressor of mothers against decapentaplegic (SMAD) signaling. Blocking proteinase-activated receptor-2 (PAR2) abrogated the DPP4-induced activation of NF-κB and SMAD and expression of fibrosis-associated proteins in fibroblasts. Linagliptin, a clinically available DPP4 inhibitor, was observed to abrogate the soluble DPP4-induced expression of fibrotic proteins. This study demonstrated the mechanism underlying soluble DPP4, which activated NF-κB and SMAD signaling through PAR2, leading to fibroblast activation. Our data extend the current view of soluble DPP4. Elevated levels of circulating soluble DPP4 may contribute to one of the mediators that induce dermal fibrosis in patients.

Cell therapy generates a favourable chemokine gradient for stem cell recruitment into the infarcted heart in rabbits.

AIMS: Stem cell recruitment into the heart is determined by a concentration gradient of stromal-derived factor 1 (SDF-1) from bone marrow to peripheral blood and from blood to injured myocardium. However, this gradient is decreased in chronic myocardial infarction (MI). This study evaluated the effect of cell therapy using bone marrow stromal cells (BMSCs) on an SDF-1 gradient in post-infarction rabbits. METHODS AND RESULTS: Myocardial infarction was induced in male New Zealand white rabbits (2.5-3 kg) by ligation of the left anterior descending coronary artery. Two months later, the rabbits were randomized to either saline or BMSC (2 x 10(6) autologous BMSCs injected into the left ventricular cavity) treatment. Four weeks after therapy, the SDF-1 gradients from bone marrow to blood and from blood to myocardium increased in the BMSC group compared with the saline group. This was accompanied by an increase in cells positive for CD34, CD117, and STRO-1 in the myocardium, resulting in more capillary density, better cardiac function, and a decrease in infarct size. CONCLUSION: Generation of an SDF-1 gradient towards the heart is a novel effect of BMSC-based cell therapy. This effect facilitates stem cell recruitment into remodelled myocardium and supports improvement in cardiac function.

Distinct functional defect of three novel Brugada syndrome related cardiac sodium channel mutations.

The Brugada syndrome is characterized by ST segment elevation in the right precodial leads V1-V3 on surface ECG accompanied by episodes of ventricular fibrillation causing syncope or even sudden death. The molecular and cellular mechanisms that lead to Brugada syndrome are not yet completely understood. However, SCN5A is the most well known responsible gene that causes Brugada syndrome. Until now, more than a hundred mutations in SCN5A responsible for Brugada syndrome have been described. Functional studies of some of the mutations have been performed and show that a reduction of human cardiac sodium current accounts for the pathogenesis of Brugada syndrome. Here we reported three novel SCN5A mutations identified in patients with Brugada syndrome in Taiwan (p.I848fs, p.R965C, and p.1876insM). Their electrophysiological properties were altered by patch clamp analysis. The p.I848fs mutant generated no sodium current. The p.R965C and p.1876insM mutants produced channels with steady state inactivation shifted to a more negative potential (9.4 mV and 8.5 mV respectively), and slower recovery from inactivation. Besides, the steady state activation of p.1876insM was altered and was shifted to a more positive potential (7.69 mV). In conclusion, the SCN5A channel defect related to Brugada syndrome might be diverse but all resulted in a decrease of sodium current.