Metal-Organic Frameworks Functionalized Separators for Lithium-Sulfur Batteries.

Lithium sulfur batteries (LSBs) have attracted tremendous attention owing to their high theoretical specific capacity and specific energy. However, their practical applications are hindered by poor cyclic life, mainly caused by polysulfide shuttling. The development of advanced materials to mitigate the polysulfide shuttling effect is urgently demanded. Metal-organic frameworks (MOFs) have been exploited as multifunctional materials for the decoration of separators owing to their high surface area, structural diversity, tunable pore size, and easy tailor ability. In this review, we aim to present the state-of-the-art MOF-based separators for LSBs. Particular attention is paid to the rational design (pore aperture, metal node, functionality, and dimension) of MOFs with enhanced ability for anchoring polysulfides and facilitating Li+ transportation. Finally, the challenges and perspectives are provided regarding to the future design MOF-based separators for high-performance LSBs.

Intervention Effect of Taurine on LPS-Induced Intestinal Mechanical Barrier Injury in Piglets.

Taurine has the advantages of being safe, highly efficient, chemically stabile, and biologically active, together with having versatile functions. Presently, it is employed as a veterinary feed additive in animal research. The tight junctions that constitute the intestinal epithelial cells are the most critical structures for ensuring regular and uninterrupted digestion and absorption of food by the intestinal mucosa, while at the same time resisting invasions by toxins. The purpose of this study was to investigate the protective effect and mechanism of taurine action on intestinal mechanical barrier function of piglets that were infected with LPS. The results showed that 0.3% taurine inhibits LPS-driven increase in intestinal permeability and intestinal mucosal injury, the rise in the ratio of villus length to crypt depth within the duodenum, jejunum, and ileum, and the significant enhancement in the expression of tight junction protein-related genes. In summary, dietary taurine significantly reduces intestinal mucosal structural damage and intestinal mucosal permeability while increasing gene expression of tight junction proteins of the intestinal mucosa of piglets induced by LPS, thereby enhancing the effect of intestinal mucosal mechanical barriers.

Taurine Prevents LPS-Induced Liver Injury in Weaned Piglets.

This study employed taurine as a feed additive to explore the prophylactic effect of taurine on LPS-induced hepatic injury in piglets. The pathological shifts within hepatic tissue were observed by HE staining. Serum levels of ALT and AST together with SOD, CAT, GSH-PX activity, and MDA serum and liver levels were detected. TUNEL was used to detect apoptosis, while qPCR was employed to detect HO-1, Nrf-2, Bcl2, BAX, Caspase-3, and NF- κB p65 transcriptomic expression levels. TRL4, Caspase-3, Nrf-2, and NF- κB p-p65/NF- κB p65 were detected by Western blot. The results revealed that taurine reduces LPS-induced pathological damage of hepatic tissue and reduces the levels of ALT and AST in pig serum. The transcriptomic expression levels of HO-1 and Nrf-2 were upregulated, and proteomic expression of Nrf-2 was increased. SOD, CAT, and GSH-PX activity was elevated, while MDA content was reduced in serum and liver. The levels of mRNA of BAX and Caspase-3 were downregulated, but mRNA content of Bcl2 was increased, and the protein levels of TRL4, NF-κB p-p65/NF-κB p65, and Caspase-3 were diminished. Overall, the degree of hepatocyte apoptosis was also significantly reduced. In conclusion, taurine reduces LPS-induced injury of piglet liver, while reducing hepatocyte apoptotic levels. These data provide a scientific basis for the selection of animal feed additives and lay a foundation for the healthy and sustainable development of the porcine industry.

High intracranial pressure may be the initial inducer of elevated plasma D-dimer level after aneurysmal subarachnoid haemorrhage.

Objective: The plasma D-dimer has been regarded as a poor prognosis factor in aneurysmal subarachnoid haemorrhage (aSAH) patients, but the reason of elevated D-dimer level has not been revealed. In this study, we retrospectively explored the potential clinical parameters which might be related to D-dimer level and further attempted to explain the pathological process of D-dimer level elevation in aSAH patients. Patients and methods: The qualified patients with aSAH were recruited and treated in Sichuan Provincial People's Hospital from 1 October 2015 to 28 February 2018. All clinical data were collected, the blood samples were gathered on admission and the levels of D-dimer were detected by the clinical laboratory. The χ2-test, univariate and multiple linear regression analysis were used to seek the relationship between clinical variables and D-dimer level.Results: Total 98 aSAH patients were enrolled. The χ2-test showed a significant difference in clinical characteristics of gender, hyperlipidaemia and ICP between the patients with normal D-dimer level and the others with a high D-dimer level (p < .05). The univariate linear regression analysis and the multiple linear regression analysis showed the combined CCT and ICP were still significantly related to D-dimer level (p < .05). Conclusion: Besides the other related factors, the increased ICP was obviously associated with the elevated plasma D-dimer level. It may indicate that the high ICP acted as the initial role, then led to poor perfusion, even induced the microthrombosis and activated the fibrinolytic system, which eventually contributed to D-dimer level increasing in aSAH patients.

Enhanced Transmission and Self-Cleaning of Patterned Sapphire Substrates Prepared by Wet Chemical Etching Using Silica Masks.

Highly transparent and superhydrophilic sapphire with surface antireflective subwavelength structures were prepared by wet etching using colloidal monolayer silica masks. The film thicknesses of the silica masks were adjusted by the volume concentrations of polystyrene spheres. The evolution of etching morphologies of sapphire was studied, and antireflective concave pyramid nanoarrays on sapphire substrates were designed by calculation and were then prepared. The transmission and wettability of as-obtained patterned sapphire substrates were also investigated. As for sapphire with optimum surface concave micropyramid arrays, average visible transmittance can reach 91.7%, which is apparently higher than that of flat sapphire (85.5%). Moreover, the concave pyramid arrays can significantly increase the surface hydrophilicity of sapphire, exhibiting a water contact angle of 12.6° compared with 62.7° of flat sapphire. The proposed method can be an excellent strategy for preparing antireflective and self-cleaning concave micropyramid subwavelength structures on sapphire without complicated equipment and expensive raw materials.

Broad-band anti-reflective pore-like sub-wavelength surface nanostructures on sapphire for optical windows.

Compared with conventional anti-reflective film, an anti-reflective sub-wavelength surface structure provides an ideal choice for a sapphire optical window especially in harsh environments. However, it is still a challenge to obtain a sapphire anti-reflective surface microstructure because of its high hardness and chemical inertness. In this paper, combined with optical simulation, we proposed a facile method based on the anodic oxidation of aluminum film and following epitaxial annealing. Al thin film was deposited on a sapphire substrate by magnetron sputtering, and anodic oxidation was then performed to prepare surface pore-like structures on the Al film. Followed by two-step annealing, both the anodic oxidized coating and underlying unoxidized Al film were transformed totally into alumina. The parameters of anodic oxidation were analyzed to obtain the optimal pore-like structures for the antireflection in the mid-infrared and visible spectrum regions, respectively. Finally, the optimized surface sub-wavelength nanostructure on sapphire can increase the transmittance by 7% in the wavelength range of 3000-5000 nm and can increase 13.2% significantly for visible spectrum region, respectively. Meanwhile, the surface wettability can be also manipulated effectively. The preparation of surface pore-like sub-wavelength structure by the annealing of anodic oxidized aluminum film on sapphire is a feasible, economical and convenient approach and can find the applications for various optoelectronic fields.

Effect of Cholesteryl Ester Transfer Protein Gene TaqIB Polymorphism on the Risk of Ischemic Stroke: A Meta-Analysis.

BACKGROUND: The association between cholesteryl ester transfer protein (CETP) TaqIB polymorphism and ischemic stroke (IS) risk has generated conflicting results. To investigate whether the TaqIB polymorphism of the CETP gene was associated with the risk of IS, a meta-analysis was performed. METHODS: Studies were retrieved by searching PubMed, Web of Science, the Chinese National Knowledge Infrastructure, the Chinese Wanfang Database, and the Chinese VIP Database before January 16, 2017. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess the association. Depending on the heterogeneity the fixed-effects model or the random-effects model was used. RESULTS: A total of 6 case-control studies were identified with 1494 cases and 1370 controls. Overall, an association of CETP TaqIB polymorphism with IS was found in the 4 genetic models (B2B2 versus B1B1: OR = .63, 95% CI = .51-.79, P < .001; B1B2 + B2B2 versus B1B1: OR = .75, 95% CI = .64-.87, P < .001; B2B2 versus B1B2 + B1B1: OR = .70, 95% CI = .57-.85, P < .001; B2 versus B1: OR = .78, 95% CI = .70-.87, P < .001). In the subgroup analysis by ethnicity, similar risks were also observed in Asian population. CONCLUSIONS: This meta-analysis indicates that CETP TaqIB polymorphism is associated with IS risk, and the B2 allele is a protective factor for IS.

An optical monitoring method for depositing dielectric layers of arbitrary thickness using reciprocal of transmittance.

An approach extracting information of both optical monitoring signal and phase thickness of deposited layer on a trace diagram is proposed. Realtime fitting and calculation are performed to get both practical thickness and refractive index of deposited layer with the assist of quartz crystal monitoring for keeping steady rate of deposition. Monitoring error of thickness using this approach is analyzed. It was used to obtain the refractive indices and thickness of Ge layer and SiO layer in in situ measurement mode, and the results were compared with those of ex-situ spectral measurement using infrared spectrometer. The effectiveness of the proposed monitoring method was verified by fabricating narrow bandpass filter consisting of quarter-wave and non-quarter-wave layers.

[Study on identification of four kinds of Gentianaceae Mongolian medicine Digeda with spectroscopy techniques].

To study the identification of Gentianaceae Mongolian medicine Digeda with spectroscopy techniques, near infrared spectroscopy and differential scanning calorimetry techniques were applied to study on the identification of 4 kinds of Gentianaceae Mongolian medicine Digeda, and characteristic spectrums obtained were systematically analyzed. In NIR study, the four species of Digeda exist some differences in 4 250-4 400 cm(-1) and 5 650-5 800 cm(-1) of one-dimensional spectra, and show significant differences in 4 100- 4 400 cm(-1), 4 401-4 900 cm(-1) and 5 400-5 800 cm(-1) of the second derivative spectra. DSC curves of them present distinct topological pattern, characteristic peak and peak temperature. Using near infrared spectroscopy and differential scanning calorimetry analysis can realize efficient and accurate identification of four kinds of Mongolian medicine Digeda, and provide scientific basis for the efficient and accurate identification of other Gentianaceae Mongolian medicine Digeda.

[Protection, exploitation and utilization states of specialized Mongolian folk medicine resources and related development strategy].

Mongolian folk medicine resource is the origin of Mongolian medicine development, even more important of which is the specialized Mongolian folk medicine resources with regional and high medicine quality, it processes distinctive national characteristics with irreplaceable important position in traditional Mongolian medicine. Nevertheless, due to the serious destroy of ecological environment and sharp increase of demands, etc. A lot of specialized Mongolian folk medicine resources were endangered, and there still existed some problems in the protection and exploitation and utilization. This paper intends to provide comprehensive insight into the species protection and exploitation and utilization states of specialized Mongolian folk medicine resources. The application and protection status and the existing problems were reviewed, and the development strategies of Mongolian folk medicine resource were analyzed.

[Study on identification of "Digeda" raw materials in Mongolian patent medicine by PCR amplification of specific alleles].

To explore a new method for identification of Mongolian patent medicine (MPM) by PCR amplification of specific alleles. Eight kinds of MPM were used to study the identification of "Digeda" raw materials. The total DNA of Lomatogonium rotatum and Corydalis bungeana samples were extracted through modified CTAB method, psbA-trnH sequence was amplified by PCR and sequenced directionally. Specific primer was designed. The DNA of 8 kinds of MPM also was extracted and purified by the commercial DNA purification kits. The rbcL and two pair of specific primers sequences were amplified. The specific amplified products were sequenced in forward directions. All specific sequences were aligned and were analyzed. The results indicated that L rotatum can be identified by specific primers from Digeda-4 Tang, Digeda-8 San, Digeda-4 San, and C. bungeana medicinal materials can be identified by specific primers from Li Dan Ba Wei San, Yi He Ha Ri-12 and A Ga Ri-35. PCR amplification of specific alleles can stably and accurately distinguish raw medicinal materials in MPM.

[Chemical constituents of leaves of Panax japonicus var. major].

Seven compounds were isolated from the leaves of Panax japonicus var. major by chromatographic methods including silica gel, Sephadex LH-20, ODS and semi-preparative HPLC. Their structures were elucidated by their physical and chemical properties and spectral data analysis as 5, 7-dihydroxy-8-methoxyl flavone (1), ginsenoside Rs2 (2), quinquenoside R1 (3), ginsenoside Rs1 (4), notoginsenoside Fe (5), ginsenoside Rd2 (6) and gypenosiden IX (7). Among them, compound 1 was obtained from the Panax genus for the first time, and compounds 2-7 were isolated from this plant for the first time.

Influence of Minimum Alveolar Concentration and Inhalation Duration of Sevoflurane on Facial Nerve Electromyography in Hemifacial Spasm: A Randomized Controlled Trial.

BACKGROUND: The lateral spread response (LSR) is an electromyography feature of hemifacial spasm; intraoperative reduction in the LSR is associated with positive surgical outcomes. This study examined the effects of different minimum alveolar concentrations (MACs) and durations of sevoflurane inhalation on the LSR. METHODS: Eighty patients undergoing microvascular decompression surgery for hemifacial spasm were randomly allocated to receive propofol-remifentanil total intravenous anesthesia alone or in combination with sevoflurane at 0.5, 0.75, or 1 MAC. The LSR and orbicularis oculi muscle wave were recorded before and at 15 and 30 minutes after the start of sevoflurane administration. RESULTS: Sevoflurane reduced the LSR amplitude in a dose-dependent and duration-dependent manner. The curve representing the LSR amplitude preservation ratio change according to sevoflurane concentration is best fitted by regression analysis using a cubic model, as the cubic equations had the largest coefficient of determination; at 15 minutes ( R2 =0.76, F =78.36, P <0.05) and at 30 minutes ( R2 =0.882, F =189.94, P <0.05). The inhibitory effect of sevoflurane on the LSR amplitude was greater in the first 15 minutes than in the second 15 minutes of sevoflurane administration. Sevoflurane at 1 MAC for 30 minutes mildly decreased the amplitude of the orbicularis oculi muscle wave. The latencies of the LSR and the orbicularis oculi muscle wave were not affected by sevoflurane at all MACs studied. CONCLUSIONS: The combination of intravenous propofol-remifentanil anesthesia with 0.5 MAC sevoflurane allows reliable intraoperative LSR monitoring in hemifacial spasm patients. Our findings support the central rather than peripheral hypothesis of the LSR.

Dietary taurine effect on intestinal barrier function, colonic microbiota and metabolites in weanling piglets induced by LPS.

Diarrhea in piglets is one of the most important diseases and a significant cause of death in piglets. Preliminary studies have confirmed that taurine reduces the rate and index of diarrhea in piglets induced by LPS. However, there is still a lack of relevant information on the specific target and mechanism of action of taurine. Therefore, we investigated the effects of taurine on the growth and barrier functions of the intestine, microbiota composition, and metabolite composition of piglets induced by LPS. Eighteen male weaned piglets were randomly divided into the CON group (basal diet + standard saline injection), LPS group (basal diet + LPS-intraperitoneal injection), and TAU + LPS group (basal diet + 0.3% taurine + LPS-intraperitoneal injection). The results show that taurine significantly increased the ADG and decreased the F/G (p < 0.05) compared with the group of CON. The group of TAU + LPS significantly improved colonic villous damage (p < 0.05). The expression of ZO-1, Occludin and Claudin-1 genes and proteins were markedly up-regulated (p < 0.05). Based on 16s rRNA sequencing analysis, the relative abundance of Lactobacilluscae and Firmicutes in the colon was significantly higher in the LPS + TAU group compared to the LPS group (p < 0.05). Four metabolites were significantly higher and one metabolite was significantly lower in the TAU + LPS group compared to the LPS group (p < 0.01). The above results show that LPS disrupts intestinal microorganisms and metabolites in weaned piglets and affects intestinal barrier function. Preventive addition of taurine enhances beneficial microbiota, modulates intestinal metabolites, and strengthens the intestinal mechanical barrier. Therefore, taurine can be used as a feed additive to prevent intestinal damage by regulating intestinal microorganisms and metabolites.

Blue-light-emitting multifunctional triphenylamine-centered starburst quinolines: synthesis, electrochemical and photophysical properties.

A series of triphenylamine-centered starburst quinolines (1a-1g) have been synthesized by Friedländer condensation of the 4,4',4''-triacetyltriphenylamine (2) and 2-aminophenyl ketones (3a-3g) in the presence of catalytic sulfuric acid and characterized well. They are thermally robust with high glass transition temperatures (above 176.4 °C) and decomposition temperatures (above 406 °C). These compounds emit blue fluorescence with λ(max)(Em) ranging from 433 to 446 nm in dilute toluene solution and 461 to 502 nm in the solid-state and have a relatively high efficiency (Φ(u) = 0.98-0.57). 1a-1g have estimated ionization potentials (IP) of 4.54 to 6.45 eV which are significantly near or higher than those of well-known electron transport materials (ETMs), including tris(8-hydroxyquinoline)aluminium (Alq(3)) (IP = 5.7-5.9 eV), and previously reported oligoquinolines (IP = 5.53-5.81 eV). Quantum chemical calculations using DFT B3LYP/6-31G* showed the highest occupied molecular orbital (HOMO) of -5.05 to -4.81 eV, which is close to the work function of indium tin oxide (ITO). These results demonstrate the potential of 1a-1g as hole-transporting/light-emitting/electron-transport materials and the host-materials of a dopant for hole-injecting for applications in organic light-emitting devices.

Anti-hyperglycemic effect of chebulagic acid from the fruits of Terminalia chebula Retz.

In the present study, we firstly compared rat intestinal α-glucosidase inhibitory activity by different ethanol-aqueous extractions from the dried fruits of Terminalia chebula Retz. The enzymatic assay showed that the 80% ethanol extract was more potent against maltase activity than both 50% and 100% ethanol extracts. By HPLC analysis, it was determined that the 80% ethanol extract had a higher content of chebulagic acid than each of 50% or 100% ethanol extract. Next, we investigated how efficiently chebulagic acid could inhibit sugar digestion by determining the glucose level on the apical side of the Caco-2 cell monolayer. The result showed that the maltose-hydrolysis activity was down-regulated by chebulagic acid, which proved to be a reversible inhibitor of maltase in Caco-2 cells. On the other hand, chebulagic acid showed a weak inhibition of sucrose-hydrolysis activity. Meanwhile, chebulagic acid did not have an obvious influence on intestinal glucose uptake and was not effective on glucose transporters. Further animal studies revealed that the oral administration of chebulagic acid (100 mg/kg body weight) significantly reduced postprandial blood glucose levels by 11.1% in maltose-loaded Sprague-Dawley (SD) rats compared with the control group, whereas the oral administration of chebulagic acid did not show a suppressive effect on postprandial hyperglycemia in sucrose- or glucose-loaded SD-rats. The results presented here suggest that chebulagic acid from T. chebula can be used to control blood glucose and manage type 2 diabetes, although clinical trials are needed.

9,9-Dibutyl-9H-fluorene-2-carbonitrile.

The fluorene fragment of the title compound, C(22)H(25)N, is essentially planar, with an r.m.s deviation of the five-membered ring of 0.005 (2) Å. The dihedral angle between this ring and the outer benzene rings are 1.5 (2) and 0.7 (2)° while that between the benzene rings is 2.1 (2)°. The cyano group makes an angle of 0.3 (2)° with the attached benzene ring.

[Effects of sympathetic nerve stimulation on connexin43 and ventricular arrhythmias during acute myocardial ischemia: experiment with rats].

OBJECTIVE: To investigate the effects of sympathetic nerve stimulation (SNS) on connexin43 (Cx43) and ventricular arrhythmias during acute myocardial ischemia (MI). METHODS: Ninety five Wistar rats were randomly divided into four groups: MI group (n=25), undergoing: ligation of the anterior descending coronary; MII-SNS group (n=25); undergoing electric stimulation of sympathetic nerve since the beginning of ligation of the anterior descending coronary and lasting till 30 min after the ligation, sympathetic nerve stimulation preconditioning + myocardial ischemia (pSNS-MI) group (n=25), undergoing electric stimulation of sympathetic nerve since the beginning of ligation of the anterior descending coronary that ended just after the ligation; and sham operation (SO) group (n=20), without coronary ligation. Ventricular arrhythmias were monitored by electrocardiography. Western blotting and RT-PCR were used to detect the protein and mRNA expression of Cx43 respectively. Immunofluorescence analysis was used to observe the changes of Cx43 protein distribution. RESULTS: One and 3 rate died due to ventricular fibrillation in the MI group and MI-SS group respectively. The incidence of ventricular tachycardia (VT)/VF within 30-minute after ligation in the MI-SNS group was 80.0%, significant higher than that of the MI group (52.0%, P < 0.05). The incidence of VT/VF within 30-minute after ligation of the pSNS-MI group was 20.0%, significantly lower than that of the MI-SNS group (P < 0.05). 30 minutes after the ligation, the percentage of phosphorylated Cx43 of the pSNS-MI and MI-SNS groups were 71.2% +/- 7.0% and 73.4% +/- 6.7% respectively, both significantly higher than that of the MI group (46.7% +/- 6.3%) (both P < 0.05). The total contents of Cx43 of the MI and pSNS-MI groups were 1.29 +/- 0.14 and 1.25 +/- 0.13 respectively, both similar to that of the SO group [(1.30 +/- 0.10), both P > 0.05], while the total Cr43 content of the MI-SNS group was 0.73 +/- 0. 12, significantly lower than that of the SO group [(1.30 +/- 0.10), P < 0.05]. The Cx43 mRNA levels of the 3 experimental groups were all significantly lower than that of the SO group (all P < 0.05). Immunofluorescence analysis confirmed that ischemia and sympathetic nerve stimulation induced the changes of connexin43 distribution and sympathetic nerve stimulation preconditioning inhibited the changes of connexin43 distribution induced by ischemia. CONCLUSION: SNS promotes ventricular arrhythmias by promoting Cx43 degradation, and sympathetic nerve stimulation preconditioning inhibits ventricular arrhythmias by preventing Cx43 dephosphorylation.

[The relationship between the aquaporin-4 and brain edema, pathologic change, ultrastructure in peri-hematoma tissue in patients with intracerebral hemorrhage].

OBJECTIVE: To observe the expression of aquaporin-4 (AQP-4) mRNA and study the relationship between AQP-4, brain edema, pathological changes and ultrastructure of peri-hematoma tissue in intracerebral hemorrhage (ICH) patients. METHODS: Intracranial operation was performed via nonfunctional area with a funnel-like approach on 30 ICH patients. The brain tissue which must be removed 1 cm away the hematoma was removed within 12 hours for observation as normal brain tissue and taken as the control group (7 patients), and which of the brain tissue within 1 cm around hematoma was taken as the study specimens. The experimental group was subdivided into five groups according to the time interval after ICH: <6 hours (6 cases), 6-12 hours (7 cases), 12-24 hours (5 cases), 24-72 hours (6 cases), and >72 hours ( 6 cases ). Expression of the AQP-4 mRNA, brain edema, pathological and ultrastructural changes were observed with reverse transcription-polymerase chain reaction (RT-PCR), light microscope and electron microscope. RESULTS: The expression of the AQP-4 mRNA was not remarkable, the morphology and construction were basically normal in control group. The expression of AQP-4 mRNA was mild (1.17+/-0.41)and there was edema of neuroglia in the <6 hours group. After 6 hours, besides neuroglial edema, the expression of the AQP-4 mRNA was gradually obvious, capillary endothelial cells began to swell too, and tight junctions gradually began to loosen. In the 12-72 hours group the expression of the AQP-4 mRNA reached its peak (3.50+/-0.55, 3.60+/-0.55, both P<0.01), and brain edema was most prominent, and electron microscopy showed that neurons, neuroglia, and capillary endothelial cells were markedly deformed. After 72 hours, the expression of AQP-4 mRNA gradually recovered, and brain cells showed less damage. On the 5th day the damage began to repair, and on the 8th day, the damage was basically repaired. The correlation analysis showed that there was a remarkable positive correlation between the expression of the AQP-4 mRNA and the degree of brain edema and the size of hematoma (r(1)=0.67, P<0.01; r(2)=0.44, P<0.05) . CONCLUSION: Secondary edema and brain damage may correlate with the expression of the AQP-4 mRNA in the peri-hematoma brain edema area. Removal of hematoma will help decrease the AQP-4 mRNA expression and brain edema damage in the early stage.

[Transmural heterogeneity of calcium handling proteins in the mechanism of porcine model of ventricular fibrillation].

OBJECTIVE: To investigate the role of heterogeneous expression of calcium handling proteins and spatial heterogeneity of APD restitution in the maintenance mechanism of ventricular fibrillation. METHODS: During programmed electrical simulation, APD restitution curves in the endocardium and epicardium of LV were constructed by plotting APD100 and diastolic interval. APD alternans, delayed after depolarization events were recorded simultaneously. Endocardial and epicardial myocytes were isolated from LV base and apex. Real time-PCR and Western blotting were performed to determine the relative messenger RNA and protein expression levels of calcium handling proteins. RESULTS: The normal hearts have spatial heterogeneity of action potential restitution property and transmural heterogeneity of calcium handling proteins. The slopes of the APD restitution curve in the endocardium were significantly steeper than those in epicardium, and the slopes of APD curve at the LV apex were significantly steeper than those in LV base. However, delayed after depolarization events with larger amplitude and earlier onset consistently occurred in the endocardium of LV base. After programmed electrical simulation, the expression of messenger RNA of RyR2, SERCA2a except for Calstabin2 significantly decreased (by 57% and 41%, respectively, P < 0.05) in the endocardium of the base, while the expression of RyR2, SERCA2a, Calstabin2 significantly increased (by 90%, 78%and 64%, respectively, P < 0.05) in the epicardium of LV base. Although transmural heterogeneity of calcium handling proteins at the LV apex were also observed after rapid pacing, there is no significant differences in the transmural heterogeneity at the LV apex compared to the LV base. The base of LV has unique calcium handling properties. CONCLUSIONS: It has been shown that Calcium cycling could modulate APD restitution property in the intact heart. The interaction between action potential and calcium dynamics instabilities is one of the most important reasons why simple criterion such as the APD restitution slope > 1 may fail to accurately predict the onset of APD alternans.