Electrical remodeling in a canine model of ischemic cardiomyopathy

The nature of electrical remodeling in a canine model of ischemic cardiomyopathy (ICM; induced by repetitive intracoronary microembolizations) that exhibits spontaneous ventricular tachycardia is not entirely clear. We used the patch-clamp technique to record action potentials and ionic currents of left ventricular myocytes isolated from the region affected by microembolizations. We also used the immunoblot technique to examine channel subunit expression in adjacent affected tissue. Ventricular myocytes and tissue isolated from the corresponding region of normal hearts served as control. ICM myocytes had prolonged action potential duration (APD) and more pronounced APD dispersion. Slow delayed rectifier current (I(Ks)) was reduced at voltages positive to 0 mV, along with a negative shift in its voltage dependence of activation. Immunoblots showed that there was no change in KCNQ1.1 (I(Ks) pore-forming or alpha-subunit), but KCNE1 (I(Ks) auxiliary or beta-subunit) was reduced, and KCNQ1.2 (a truncated KCNQ1 splice variant with a dominant-negative effect on I(Ks)) was increased. Transient outward current (I(to)) was reduced, along with an acceleration of the slow phase of recovery from inactivation. Immunoblots showed that there was no change in Kv4.3 (alpha-subunit of fast-recovering I(to) component), but KChIP2 (beta-subunit of fast-recovering component) and Kv1.4 (alpha-subunit of slow-recovering component) were reduced. Inward rectifier current was reduced. L-type Ca current was unaltered. The immunoblot data provide mechanistic insights into the observed changes in current amplitude and gating kinetics of I(Ks) and I(to). We suggest that these changes, along with the decrease in inward rectifier current, contribute to APD prolongation in ICM hearts.     

The Effect of Stratification and Thidiazuron Treatment on Germination and Protein Synthesis of Pyrus serotina Rehd cv. Niauli

Breakage of seed dormancy in Pyrus serotina Rhed cv. Niauliis achieved by cold treatment. The chilling time necessary forgermination of Pyrus serotina Rhed cv. Niauli seeds was determined,and synthesis of polypeptides during stratification and thidiazuron(TDZ) treatments was investigated. The chilling time requiredwas about 21 d. The longer the chilling time, the higher thegermination percentage. The effect of 200 µM TDZ on seedgermination was equivalent to 14-21 d of chilling, and TDZ couldbe used as a substitute for cold treatment. Use of in vivo ³⁵S-methionine label and two-dimensional gel electrophoretic analysisof polypeptides revealed that the patterns of untreated (dormant)and chilled embryonic axes differed significantly in their polypeptideprofiles. The difference became conspicuous after prolongedchilling exposure. During 28 d of stratification followed by5 d of incubation at 25 °C, changes were noted in 35 solublepolypeptides (ESPs) and 38 pellet polypeptides (EPPs) from theembryonic axis. The changes included increase, decrease or newlyinduced synthesis. Common patterns of changes in soluble andpellet polypeptides of embryonic axes, can be broken down intofour categories. The possible functions and roles of these fourcategories of polypeptides in breaking seed dormancy and germinationare discussed. Although the magnitude of polypeptide changesare not as extensive in seeds receiving TDZ treatment as afterstratification, similar polypeptide changes were co-inducedby the two treatments.Copyright 1994, 1999 Academic Press Stratification, protein synthesis, pear, Pyrus serotina, Thidiazuron, TDZ     

Randomized controlled trial testing weight loss and abdominal obesity outcomes of moxibustion

Background

The purpose of this study was to investigate the efficacy of moxibustion therapy on weight loss, waist circumference and waist-to-hip ratio in young adult females. An experimental design, 51 Asian females were enrolled. Inclusion criteria included females with ages between 21 and 25 years-old and waist circumference?≥?80 cm, and the exclusion criteria included intolerance to moxibustion therapy and current illness. Two groups were formed, and the subjects in the experimental group received moxibustion sessions lasting 20 min and an educational video program for 30 min; however, participants in the control group received only the educational program every other week for 8 weeks. Dependent variable measurements (e.g., body weight, waist circumference and waist-to-hip ratio) were collected at baseline and follow-up for 8 weeks.

Results

Average body weight of the treatment group decreased significantly from ??1.478 kg (p?<?0.0001), while the average body weight in the control group did not decrease significantly ??0.038 kg (p?=?0.7197). Also, individuals in the moxibustion experimental group showed significant reductions (p?<?0.0001) in both waist circumference and waist-to-hip ratio.

Conclusion

Positive effects on anthropometry can be achieved by moxibustion intervention in conjunction with a weight loss education program. Especially waist circumference and waist-to-hip ratio had more clinically significant and more pronounced for health reasons Future studies can focus on the functional assessment of biomarkers associated with the immune system and relevant mechanisms of action.

     

Novel effects of clotrimazole on Ca2+ signaling in Madin Darby canine kidney cells

The effect of clotrimazole on Ca2+ signaling in Madin Darby canine kidney (MDCK) cells was investigated by using fura-2 as a Ca2+ indicator. Clotrimazole (1-30 microM) induced a concentration-dependent [Ca2+]i increase. The [Ca2+]i increase comprised an initial rise and a slow decay. External Ca2+ removal partly inhibited the Ca2+ signals by reducing both the initial rise and the decay phase, indicating that clotrimazole triggered both Ca2+ influx and Ca2+ release. Pretreatment with 30 microM clotrimazole in Ca2+-free medium abolished the Ca2+ release induced by thapsigargin (1 microM), an endoplasmic reticulum Ca2+ pump inhibitor, and conversely, pretreatment with thapsigargin prevented clotrimazole from releasing more Ca2+. This suggests that the thapsigargin-sensitive Ca2+ store is the source of clotrimazole-induced Ca2+ release. Clotrimazole (10 microM) triggered Mn2+ quench of fura-2 fluorescence which was partly inhibited by 1 mM La3+. Addition of 3 mM Ca2+ induced a [Ca2+]i increase after preincubation with 10 microM clotrimazole in Ca2+-free medium, indicating that clotrimazole activated capacitative Ca2+ entry. However, 10 and 30 microM clotrimazole inhibited 1 microM thapsigargin-induced capacitative Ca2+ entry by 21% and 74%, respectively. Pretreatment with 40 microM aristolochic acid to inhibit phospholipase A2 reduced 30 microM clotrimazole-induced Ca2+ release by 51%, but inhibiting phospholipase C with 2 microM U73122 had little effect. This implies that clotrimazole induces Ca2+ release in an IP3-independent manner, which could be modulated by phospholipase A2-coupled events.     

Phylogenetic analyses of potassium channel auxiliary subunits

Results of recent genome-sequencing projects together with advances in biochemical, molecular genetic and physiological experimentation have allowed discovery of many transport auxiliary subunits. These subunits facilitate the proper movement of substrates across cell membranes. Mutations of any of these subunits can cause catastrophic effects to the transport mechanism and cause certain genetic diseases. Auxiliary subunits of ion channels are of particular interest because of their potential to diversify the transport properties of the principal subunits. Furthermore, ion channel auxiliary subunits may function in the capacity of enhancing surface expression, allowing gating, and providing chaperone-like activities. As a result of their evolutionary histories, these proteins can be grouped exclusively by phylogenetic techniques. Many of these families are found to be restricted to a single kingdom of life while others seem to be ubiquitous. Here we report the results of systematic analyses of three families of ion channel auxiliary subunits. Some subunits contain one or more transmembrane segments while others exist only in the cytoplasm. We have also observed potential horizontal transfer across kingdoms with these auxiliary subunits. In this report, we present tabulated results of homology searches, partial multiple alignments, secondary structure analyses, and phylogenetic trees for these families.     

Enhancement of cell growth in tissue-engineering constructs under direct perfusion: Modeling and simulation

Perfusion bioreactors improve mass transfer in cell-scaffold constructs. We developed a mathematical model to simulate nutrient flow through cellular constructs. Interactions among cell proliferation, nutrient consumption, and culture medium circulation were investigated. The model incorporated modified Contois cell-growth kinetics that includes effects of nutrient saturation and limited cell growth. Nutrient uptake was depicted through the Michaelis-Menton kinetics. To describe the culture medium convection, the fluid flow outside the cell-scaffold construct was described by the Navier-Stokes equations, while the fluid dynamics within the construct was modeled by Brinkman's equation for porous media flow. Effects of the media perfusion were examined by including time-dependant porosity and permeability changes due to cell growth. The overall cell volume was considered to consist of cells and extracellular matrices (ECM) as a whole without treating ECM separately. Numerical simulations show when cells were cultured subjected to direct perfusion, they penetrated to a greater extent into the scaffold and resulted in a more uniform spatial distribution. The cell amount was increased by perfusion and ultimately approached an asymptotic value as the perfusion rates increased in terms of the dimensionless Peclet number that accounts for the ratio of nutrient perfusion to diffusion. In addition to enhancing the nutrient delivery, perfusion simultaneously imposes flow-mediated shear stress to the engineered cells. Shear stresses were found to increase with cell growth as the scaffold void space was occupied by the cell and ECM volumes. The macro average stresses increased from 0.2 mPa to 1 mPa at a perfusion rate of 20 microm/s with the overall cell volume fraction growing from 0.4 to 0.7, which made the overall permeability value decrease from 1.35 x 10(-2)cm(2) to 5.51 x 10(-4)cm(2). Relating the simulation results with perfusion experiments in literature, the average shear stresses were below the critical value that would induce the chondrocyte necrosis.     

Epistasis Analysis for Estrogen Metabolic and Signaling Pathway Genes on Young Ischemic Stroke Patients

Background

Endogenous estrogens play an important role in the overall cardiocirculatory system. However, there are no studies exploring the hormone metabolism and signaling pathway genes together on ischemic stroke, including sulfotransferase family 1E (SULT1E1), catechol-O-methyl-transferase (COMT), and estrogen receptor α (ESR1).

Methods

A case-control study was conducted on 305 young ischemic stroke subjects aged ≦ 50 years and 309 age-matched healthy controls. SULT1E1 -64G/A, COMT Val158Met, ESR1 c.454−397 T/C and c.454−351 A/G genes were genotyped and compared between cases and controls to identify single nucleotide polymorphisms associated with ischemic stroke susceptibility. Gene-gene interaction effects were analyzed using entropy-based multifactor dimensionality reduction (MDR), classification and regression tree (CART), and traditional multiple regression models.

Results

COMT Val158Met polymorphism showed a significant association with susceptibility of young ischemic stroke among females. There was a two-way interaction between SULT1E1 -64G/A and COMT Val158Met in both MDR and CART analysis. The logistic regression model also showed there was a significant interaction effect between SULT1E1 -64G/A and COMT Val158Met on ischemic stroke of the young (P for interaction = 0.0171). We further found that lower estradiol level could increase the risk of young ischemic stroke for those who carry either SULT1E1 or COMT risk genotypes, showing a significant interaction effect (P for interaction = 0.0174).

Conclusions

Our findings support that a significant epistasis effect exists among estrogen metabolic and signaling pathway genes and gene-environment interactions on young ischemic stroke subjects.     

Furano-1,2-naphthoquinone inhibits EGFR signaling associated with G2/M cell cycle arrest and apoptosis in A549 cells

Furano-1,2-naphthoquinone (FNQ), prepared from 2-hydroxy-1,4-naphthoquinone and chloroacetaldehyde in an efficient one-pot reaction, exhibits an anti-carcinogenic effect. FNQ exerted anti-proliferative activity with the G(2)/M cell cycle arrest and apoptosis in A549 cells. FNQ-induced G(2)/M arrest was correlated with a marked decrease in the expression levels of cyclin A and cyclin B, and their activating partner cyclin-dependent kinases (Cdk) 1 and 2 with concomitant induction of p53, p21, and p27. FNQ-induced apoptosis was accompanied with Bax up-regulation and the down-regulation of Bcl-2, X-linked inhibitor of apoptosis (XIAP), and survivin, resulting in cytochrome c release and sequential activation of caspase-9 and caspase-3. Western blot analysis revealed that FNQ suppressed EGFR phosphorylation and JAK2, STAT3, and STAT5 activation, but increased in activation of p38 MAPK and c-Jun NH2-terminal kinase (JNK) stress signal. The combined treatment of FNQ with AG1478 (a specific EGFR inhibitor) significantly enhanced the G(2)/M arrest and apoptosis, and also led to up-regulation in Bax, p53, p21, p27, release of mitochondrial cytochrome c, and down-regulation of Bcl-2, XIAP, survivin, cyclin A, cyclin B, Cdk1, and Cdk2 in A549 cells. These findings suggest that FNQ-mediated cytotoxicity of A549 cell related with the G(2)/M cell cycle arrest and apoptosis via inactivation of EGFR-mediated signaling pathway.