Novel Peak Shift Correction Method Based on the Retention Index for Peak Alignment in Untargeted Metabolomics.

Peak alignment is a crucial step in liquid chromatography-mass spectrometry (LC-MS)-based large-scale untargeted metabolomics workflows, as it enables the integration of metabolite peaks across multiple samples, which is essential for accurate data interpretation. Slight differences or fluctuations in chromatographic separation conditions, however, can cause the chromatographic retention time (RT) shift between consecutive analyses, ultimately affecting the accuracy of peak alignment between samples. Here, we introduce a novel RT shift correction method based on the retention index (RI) and apply it to peak alignment. We synthesized a series of N-acyl glycine (C2-C23) homologues via the amidation reaction between glycine with normal saturated fatty acids (C2-C23) as calibrants able to respond proficiently in both mass spectrometric positive- and negative-ion modes. Using these calibrants, we established an N-acyl glycine RI system. This RI system is capable of covering a broad chromatographic space and addressing chromatographic RT shift caused by variations in flow rate, gradient elution, instrument systems, and LC separation columns. Moreover, based on the RI system, we developed a peak shift correction model to enhance peak alignment accuracy. Applying the model resulted in a significant improvement in the accuracy of peak alignment from 15.5 to 80.9% across long-term data spanning a period of 157 days. To facilitate practical application, we developed a Python-based program, which is freely available at https://github.com/WHU-Fenglab/RI-based-CPSC.

Uncovering the Carboxylated Metabolome in Gut Microbiota-Host Co-metabolism: A Chemical Derivatization-Molecular Networking Approach.

Gut microbiota-host co-metabolites serve as essential mediators of communication between the host and gut microbiota. They provide nutrient sources for host cells and regulate gut microenvironment, which are associated with a variety of diseases. Analysis of gut microbiota-host co-metabolites is of great significance to explore the host-gut microbiota interaction. In this study, we integrated chemical derivatization, liquid chromatography-mass spectrometry, and molecular networking (MN) to establish a novel CD-MN strategy for the analysis of carboxylated metabolites in gut microbial-host co-metabolism. Using this strategy, 261 carboxylated metabolites from mouse feces were detected, which grouped to various classes including fatty acids, bile acids, N-acyl amino acids, benzoheterocyclic acids, aromatic acids, and other unknown small-scale molecular clusters in MN. Based on the interpretation of the bile acid cluster, a novel type of phenylacetylated conjugates of host bile acids was identified, which were mediated by gut microbiota and exhibited a strong binding ability to Farnesoid X receptor and Takeda G protein-coupled receptor 5. Our proposed strategy offers a promising platform for uncovering carboxylated metabolites in gut microbial-host co-metabolism.

Alternating Dual-Collision Energy Scanning Mass Spectrometry Approach: Discovery of Novel Microbial Bile-Acid Conjugates.

Bile acids (BAs) are a type of gut microbiota-host cometabolites with abundant structural diversity, and they play critical roles in maintaining host-microbiota homeostasis. In this study, we developed a new N-(4-aminomethylphenyl) pyridinium (AMPP) derivatization-assisted alternating dual-collision energy scanning mass spectrometry (AMPP-dual-CE MS) method for the profiling of BAs derived from host-gut microbiota cometabolism in mice. Using the proposed method, we discovered two new types of amino acid conjugations (alanine conjugation and proline conjugation) and acetyl conjugation with host BAs, for the first time, from mouse intestine contents and feces. Additionally, we also determined and identified nine new leucine- and phenylalanine-conjugated BAs. These findings broaden our knowledge of the composition of the BA pool and provide insight into the mechanism of host-gut microbiota cometabolism of BAs.

Integration of Chemical Derivatization and in-Source Fragmentation Mass Spectrometry for High-Coverage Profiling of Submetabolomes.

In-source fragmentation-based high-resolution mass spectrometry (ISF-HRMS) is a potential analytical technique, which is usually used to profile some specific compounds that can generate diagnostic neutral loss (NL) or fragment ion (FI) in ion source inherently. However, the ISF-HRMS method does not work for those compounds that cannot inherently produce diagnostic NL or FI in ion source. In this study, a derivatization-based in-source fragmentation-information-dependent acquisition (DISF-IDA) strategy was proposed for profiling the metabolites with easily labeled functional groups (submetabolomes) by liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry (LC-ESI-Q-TOF MS). As a proof-of-concept study, 36 carboxylated compounds labeled with N,N-dimethylethylenediamine (DMED) were selected as model compounds to examine performance of DISF-IDA strategy in screening the carboxylated metabolites and acquiring their MSn spectra. In ESI source, the DEMD-derived carboxylated compounds were fragmented to produce characteristic neutral losses of 45.0578, 63.0684, and/or 88.1000 Da that were further used as diagnostic features for screening the carboxylated metabolites by DISF-IDA-based LC-Q-TOF MS. Furthermore, high-resolution MSn spectra of the model compounds were also obtained within a single run of DISF-IDA-based LC-Q-TOF MS analysis, which contributed to the improvement of the annotation confidence. To further verify its applicability, DISF-IDA strategy was used for profiling carboxylated submetabolome in mice feces. Using this strategy, a total of 351 carboxylated metabolites were detected from mice feces, of which 178 metabolites (51% of the total) were positively or putatively identified. Moreover, DISF-IDA strategy was also demonstrated to be applicable for profiling other submetabolomes with easily labeled functional groups such as amino, carbonyl, and cis-diol groups. Overall, our proposed DISF-IDA strategy is a promising technique for high-coverage profiling of submetabolomes with easily labeled functional groups in biological samples.

A genetic variant in a homocysteine metabolic gene that increases the risk of congenital cardiac septal defects in Han Chinese populations.

Elevated homocysteine levels are known to be a risk factor for congenital cardiac septal defects (CCSDs), but the mechanism underlying this effect is unknown. The genetic variants that were significantly associated with circulating homocysteine concentrations have been systematically identified through the genome-wide association studies of one-carbon core metabolites. To examine the role of the genome-wide significant homocysteine related variants in the occurrence of CCSDs, we investigated the association between these variants and CCSDs in Han Chinese populations. Five variants of the genome-wide significant homocysteine-related genes were selected for analysis in two stages of case-controlled studies with a total of 904 CCSD patients and 997 controls. SYT9 expression was detected in human cardiovascular tissue using qRT-PCR. The intronic variant rs11041321 of the SYT9 gene was associated with an increased risk of developing CCSDs in both the separate and combined case-controlled studies. Combined samples from the two stage cohorts had a significant elevation in CCSD risk for the T allele (OR = 1.43, P = 2.6 × 10-6 ), CT genotype and TT genotype (CT: OR = 1.30, TT: OR = 2.21; P = 1 × 10-4 ) compared with the wild-type C allele and CC genotype, respectively. The risky T allele carriers exhibited decreased SYT9 mRNA expression, compared with wild-type C allele carriers. The intronic SYT9 variant rs11041321, which exhibits a significant genome-wide association with circulating homocysteine, was associated with the occurrence of CCSDs. This finding helps to characterize the unexpected role of SYT9 in homocysteine metabolism and the development of CCSDs, which further highlighted the interplay of diet, genetics, and human birth defects. © 2017 IUBMB Life, 69(9):700-705, 2017.

[Alignment method for metabolite chromatographic peaks using an N-acyl glycine retention index system].

Peak alignment is a crucial data-processing step in untargeted metabolomics analysis that aims to integrate metabolite data from multiple liquid chromatography-mass spectrometry (LC-MS) batches for enhanced comparability and reliability. However, slight variations in the chromatographic separation conditions can result in retention time (RT) shifts between consecutive analyses, adversely affecting peak alignment accuracy. In this study, we present a retention index (RI)-based chromatographic peak-shift correction (CPSC) strategy to address RT shifts and align chromatographic peaks for metabolomics studies. A series of N-acyl glycine homologues (C2-C23) was synthesized as calibrants, and an LC RI system was established. This system effectively corrected RT shifts arising from variations in flow rate, gradient elution, instrument systems, and chromatographic columns. Leveraging the RI system, we successfully adjusted the RT of raw data to mitigate RT shifts and then implemented the Joint Aligner algorithm for peak alignment. We assessed the accuracy of the RI-based CPSC strategy using pooled human fecal samples as a test model. Notably, the application of the RI-based CPSC strategy to a long-term dataset spanning 157 d as an illustration revealed a significant enhancement in peak alignment accuracy from 15.5% to 80.9%, indicating its ability to substantially improve peak-alignment precision in multibatch LC-MS analyses.

A strategy for screening and identification of new amino acid-conjugated bile acids with high coverage by liquid chromatography-mass spectrometry.

Bile acids (BAs) are a class of vital gut microbiota-host cometabolites, and they play an important role in maintaining gut microbiota-host metabolic homeostasis. Very recently, a new mechanism of BA anabolic metabolism mediated by gut microbiota (BA-amino acid conjugation) has been revealed, which provides a perspective for the research on BA metabolism and gut metabolome. In this study, we established a polarity-switching multiple reaction monitoring mass spectrometry-based screening method to mine amino acid-conjugated bile acids (AA-BAs) derived from host-gut microbiota co-metabolism. In addition, a retention time-based annotation strategy was further proposed to identify the AA-BA isomers and epimers. Using the developed methods, we successfully screened 118 AA-BA conjugates from mouse and human feces, 28 of them were confirmed by standards, and 62 putatively identified based on their predicted retention times. Moreover, we observed that the levels of most AA-BAs were significantly downregulated in the feces of chronic sleep deprivation mice, suggesting that the AA-BA metabolism was closely related to the physiological state of the host.

In-depth profiling of di(2-ethylhexyl) phthalate metabolic footprints in rats using click chemistry-mass spectrometry probes.

Di(2-ethylhexyl) phthalate (DEHP), the most widely used plasticizers in the world, has been regarded as an endocrine disrupting chemical with serious adverse health outcomes. Accumulating evidence strongly suggests that the undesirable biological effects of DEHP are meditated by its metabolites rather than itself. However, the metabolic footprints of DEHP in vivo are still unclear. Here we developed a click chemistry-assisted mass spectrometry (CC-MS) strategy for in-depth profiling DEHP metabolites in rats. An alkyne-modified DEHP analogue (alkyne-DEHP) was synthesized as a tracer for in vivo tracing, and a pair of MS probes (4-azido-nphenylbenzamide, 4-ANPA, and its deuterated reagent d5-4-ANPA) were prepared to specifically label the alkyne-DEHP metabolites, and prominently improve their detection sensitivity and selectivity. Using the CC-MS strategy, we successfully screened 247 alkyne-DEHP metabolites from rat urine, feces, and serum, including many unrevealed metabolites, such as oxidized phthalate diester metabolites and glucuronides of phthalate monoester metabolites. The discovery of new DEHP metabolites provides additional insights for understanding the metabolism of DEHP, which may be beneficial in exploring the mechanism underlying DEHP induced-toxicity in the future.

Fractional flow reserve measured via left internal mammary artery after coronary artery bypass grafting: Two case reports.

BACKGROUND: The fractional flow reserve (FFR) has made the treatment of coronary heart disease more precise. However, there are few reports on the measurement of FFR via the left internal mammary artery (LIMA). Herein, we described the determination of further treatments by measuring FFR via the LIMA in 2 cases after coronary artery bypass grafting (CABG). CASE SUMMARY: Case 1 was a 66-year-old male who was admitted due to "chest tightness after CABG." The patient underwent CABG 7 years prior due to coronary heart disease. Coronary artery angiography showed complete occlusion of the left anterior descending artery (LAD), and subtotal occlusion of the third segment of the right coronary artery. On arterial angiography, there was 85% stenosis at the distal end of the anastomosis of the LIMA-LAD graft. FFR via LIMA was determined at 0.75. Thus, balloon dilation was performed in Case 1. FFR after balloon dilation was 0.94. Case 2 was a 60-year-old male who was admitted due to "chest tightness after CABG." The patient underwent CABG 6 years prior due to coronary heart disease. There was 60% segmental stenosis in the middle segment of LAD and 75% anastomotic stenosis. FFR measured via LIMA was 0.83 (negative); thus the intervention was not performed. Case 2 was given drug treatments. At the 3-mo follow-up, there was no recurrence of chest tightness or shortness of breath in both cases. They are currently under continual follow-up. CONCLUSION: We provided evidence that FFR measurement via grafted blood vessels, especially LIMA, after CABG is a good method to determine the intervention course.

[Pollution Characteristics and Source Apportionment of VOCs in Urban Areas of Liaocheng in Summer].

Based on the online monitoring data of volatile organic compounds(VOCs) and ozone(O3) in Liaocheng in June 2021, the concentration levels, compositional characteristics, daily variation characteristics, and ozone formation potential(OFP) of VOCs on polluted days and clean days were systematically analyzed. Potential source areas of VOCs were identified by the potential source contribution function(PSCF) and concentration-weighted trajectory(CWT). The sources of VOCs in Liaocheng were analyzed using the characteristic species ratio and positive matrix factorization(PMF). The results showed that the hourly mean values of VOCs concentrations on polluted days and clean days in Liaocheng in June 2021 were(115.38±59.12) µg·m-3 and(88.10±33.04) µg·m-3, respectively, and the concentration levels of VOCs in each category showed that oxygenated volatile organic compounds(OVOCs)>alkanes>halogenated hydrocarbons>aromatic hydrocarbons>alkenes>alkynes>organosulfur. VOCs species with large differences in concentrations between polluted and clean days were among the top ten species of the hourly mean VOCs concentrations. The daily trends of concentrations of total VOCs, alkanes, alkynes, aromatic hydrocarbons, halogenated hydrocarbons, and organosulfur showed that the daytime concentrations were lower than the nighttime concentrations, and the daily changes in OVOCs concentrations showed the characteristics of high in the daytime and low at nighttime. The OFP was 285.29 µg·m-3 on polluted days and 212.00 µg·m-3 on clean days, and OVOCs, alkenes, and aromatic hydrocarbons contributed significantly to ozone formation. The PSCF and CWT results found that the potential source areas of VOCs in Liaocheng were concentrated in the northern and northeastern part of Dongchangfu District and the central and southwestern part of Chiping District. The results of the characteristic species ratio indicated that the VOCs in Liaocheng might have been more from coal combustion, gasoline volatilization, and motor vehicle exhaust. The results of PMF showed that industrial emission sources(30.57%), motor vehicle exhaust and oil and gas volatilization sources(19.44%), combustion sources(17.23%), air aging and secondary generation sources(13.69%), solvent usage sources(12.75%), and natural sources(6.32%) were the main sources of VOCs in Liaocheng.

Overexpression of lncRNA Dancr inhibits apoptosis and enhances autophagy to protect cardiomyocytes from endoplasmic reticulum stress injury via sponging microRNA-6324.

Endoplasmic reticulum stress (ERS) contributes to the pathogenesis of myocardial ischemia/reperfusion injury and myocardial infarction (MI). Long non-coding RNAs (lncRNAs) serve an important role in cardiovascular diseases, and lncRNA discrimination antagonizing non-protein coding RNA (Dancr) alleviates cardiomyocyte damage. microRNA (miR)-6324 was upregulated in MI model rats and was predicted to bind to Dancr. The present study aimed to investigate the role of Dancr in ERS-induced cardiomyocytes and the potential underlying mechanisms. Tunicamycin (Tm) was used to induce ERS. Cell viability, apoptosis and levels of associated proteins, ERS and autophagy in Dancr-overexpression H9C2 cells and miR-6234 mimic-transfected H9C2 cells were assessed using Cell Counting Kit-8, TUNEL staining and western blot assay, respectively. The results suggested that Dancr expression levels and cell viability were downregulated by Tm in a concentration-dependent manner compared with the control group. Tm induced apoptosis, ERS and autophagy, as indicated by an increased ratio of apoptotic cells, increased expression levels of Bax, cleaved (c)-caspase-3/9, glucose-regulated protein 78 kDa (GRP78), phosphorylated (p)-inositol-requiring enzyme-1α (IRE1α), spliced X-box-binding protein 1 (Xbp1s), IRE1α, activating transcription factor (ATF)6, ATF4, Beclin 1 and microtubule associated protein 1 light chain 3α (LC3)II/I, and decreased expression levels of Bcl-2, unspliced Xbp1 (Xbp1u) and p62 in the Tm group compared with the control group. Moreover, the results indicated that compared with the Tm + overexpression (Oe)-negative control (NC) group, the Tm + Oe-Dancr group displayed decreased apoptosis, but enhanced ERS and autophagy to restore cellular homeostasis. Compared with the Tm + Oe-NC group, the Tm + Oe-Dancr group decreased the ratio of apoptotic cells, decreased expression levels of Bax, c-caspase-3/9 and Xbp1u, and increased expression levels of Bcl-2, p-IRE1α, Xbp1s, Beclin 1 and LC3II/I. Dancr overexpression also significantly downregulated miR-6324 expression compared with Oe-NC. The dual-luciferase reporter assay further indicated an interaction between Dancr and miR-6324. In addition, miR-6324 mimic partially reversed the effects of Dancr overexpression on Tm-induced apoptosis, ERS and autophagy. In conclusion, lncRNA Dancr overexpression protected cardiomyocytes against ERS injury via sponging miR-6324, thus inhibiting apoptosis, enhancing autophagy and restoring ER homeostasis.

Dickkopf­1/cysteine­rich angiogenic inducer 61 axis mediates palmitic acid­induced inflammation and apoptosis of vascular endothelial cells.

Cardiovascular diseases (CVDs) are a major cause of mortality around the world, and the presence of atherosclerosis is the most common characteristic in patients with CVDs. Cysteine­rich angiogenic inducer 61 (CCN1) has been reported to serve an important role in the pathogenesis of atherosclerotic lesions. The aim of the present study was to investigate whether CCN1 could regulate the inflammation and apoptosis of endothelial cells induced by palmitic acid (PA). Dickkopf­1 (DKK1) is an important antagonist of the Wnt signaling pathway, which can specifically inhibit the classic Wnt signaling pathway. Firstly, the mRNA and protein expression levels of CCN1 were detected. Additionally, endothelial nitric oxide (NO) synthase (eNOS), DKK1, ß­catenin, and inflammation­ and apoptosis­associated proteins were measured. Detection of NO was performed using a commercial kit. The expression levels of inflammatory cytokines were assessed to explore the effect of CCN1 on PA­induced inflammation. TUNEL assay was used to detect the apoptosis of endothelial cells. The results revealed that PA upregulated the expression levels of CCN1, inflammatory cytokines and pro­apoptotic proteins in endothelial cells. PA decreased the production of NO, and the levels of phosphorylated­eNOS, whereas knockdown of CCN1 partially abrogated these effects triggered by PA. Furthermore, the Wnt/ß­catenin signaling pathway was activated in PA­induced endothelial cells; however, the levels of DKK1 were downregulated. Overexpression of DKK1 could reduce CCN1 expression via inactivation of the Wnt/ß­catenin signaling pathway. In conclusion, knockdown of CCN1 attenuated PA­induced inflammation and apoptosis of endothelial cells via inactivating the Wnt/ß­catenin signaling pathway.

The curative effect of synthetic treatment for refractory acute myocardial infarction.

BACKGROUND: This study aims to investigate the curative effect of synthetic treatment for refractory acute myocardial infarction (AMI). METHODS: A total of 76 patients with coronary AMI accompanied by shock, who were treated with combined therapy from August 1999 to April 2017, were included into this study. Sixty patients received emergency percutaneous coronary intervention (PCI). Among these patients, 39 patients received intra-aortic balloon counterpulsation (IABP), eight patients had failed PCI underwent emergency off-pump coronary artery bypass (E-OPCAB), and eight patients were treated by hybrid cardiac surgery. RESULTS: All patients were successfully rescued. However, two patients died afterward due to postoperative complications. CONCLUSIONS: For AMI patients complicated with shock, especially when emergency PCI fails or is difficult to perform, PCI + IABP, emergency E-OPCAB and hybrid cardiac surgery should be carried out, in order to achieve a good outcome and improve the success rate of rescue for this group of patients. KEYWORDS: Acute myocardial infarction (AMI); emergency percutaneous coronary intervention (PCI); intra-aortic balloon counterpulsation (IABP); emergency off-pump coronary artery bypass (E-OPCAB); hybrid cardiac surgery.

[Study on the extraction of polysaccharides from Marasmius androsaceus Mycelium].

OBJECTIVE: To optimize the extraction condition for the polysaccharides from Marasmius androsaceus Mycelium. METHODS: The single factor tests and response surface methodology (RSM) were applied. Overall research was proceeded by rational desingn. Technological condition parameters were determined according to regression analysis by SAS. RESULTS: The optimum condition was as follows: extraction temperature was 78 degrees C , extraction-duration was 1. 5h, water to material ratio was 36: 1. The optimum extracting rate for the polysaccharide was 11. 59%. CONCLUSION: The RSM is for optimum extraction process and it will improve the extraction conditions of polysaccharides.

Leptin induces hypertrophy via endothelin-1-reactive oxygen species pathway in cultured neonatal rat cardiomyocytes.

BACKGROUND: Obesity is a major risk factor for the development of cardiovascular disease. Emerging evidence indicates that leptin, a protein encoded by the obesity gene, is linked with cardiac hypertrophy in obese humans and directly induces cardiomyocyte hypertrophy in vitro. However, the mechanisms by which leptin induces cardiomyocyte hypertrophy are poorly understood. METHODS AND RESULTS: This study investigated how leptin contributes to cardiomyocyte hypertrophy. Cultured neonatal rat cardiomyocytes were used to evaluate the effects of leptin on hypertrophy. Both endothelin-1 (ET-1) and reactive oxygen species (ROS) levels were elevated in a concentration-dependent manner in cardiomyocytes treated with leptin for 4 hours compared with those cells without leptin treatment. ET-1 stimulated ROS production in a concentration-dependent manner in cardiomyocytes. The augmentation of ROS levels in cardiomyocytes treated with both leptin and ET-1 was reversed by a selective ET(A) receptor antagonist, ABT-627, and catalase, a hydrogen peroxide-decomposing enzyme. After treatment for 72 hours, leptin or ET-1 concentration-dependently increased total RNA levels, cell surface areas, and protein synthesis in cardiomyocytes, all of which were significantly inhibited by ABT-627 or catalase treatment. CONCLUSIONS: These findings indicate that leptin elevates ET-1 and ROS levels, resulting in hypertrophy of cultured neonatal rat cardiac myocytes. The ET-1-ET(A)-ROS pathway may be involved in cardiomyocyte hypertrophy induced by leptin. ET(A) receptor antagonists and antioxidant therapy may provide an effective means of ameliorating cardiac dysfunction in obese humans.

[Reactive oxygen species mediate cultured neonatal rat cardiac myocyte hypertrophy induced by endothelin-1].

The effects of endothelin-1 (ET-1) and other drugs on the reactive oxygen species (ROS) generation and cardiomyocyte hypertrophy were examined in experiments on the cultured neonatal rat cardiomyocytes. The role of ROS on neonatal rat cardiomyocyte hypertrophy induced by ET-1 was studied and the relationship of PKC activation and ROS generation was investigated. The level of intracellular ROS was measured by the ROS-specific probe 2',7'-dichlorofluorescin diacetate (DCF-DA). Cardiomyocyte hypertrophy was determined by the RNA content, the total protein of cells and the cell surface area. The results are as follows. The fluorescence intensity of intracellular DCF-DA increased by 77% in cultured neonatal rat cardiac myocytes treated with ET-1 (10 nmol/L) vs control group. Compared with control group, the fluorescence intensity of intracellular PI, protein content and cell surface area increased by 128%, 87% and 151% respectively (all P<0.01) in cardiac myocytes treated with ET-1 (10 nmol/L). ABT-627, CC, or CAT inhibited the ET-1-induced increase in fluorescence intensity of intracellular DCF-DA by 62%,60% and 51% respectively (all P<0.01), and also attenuated the cardiac hypertrophy. The fluorescence intensity of intracellular DCF-DA increased by 74% (P<0.01) in myocytes treated with PMA (1 micromol/L) vs control group. Therefore, in the course of cardiomyocyte hypertrophy, ET-1 increases intracellular ROS in the cultured neonatal rat cardiac myocytes and inhibits cardiomyocyte hypertrophy induced by ROS. The ET(A) and PKC activation mediate the ROS production and cardiomyocyte hypertrophy induced by ET-1. ROS is necessary in the ET-1-induced cardiomyocyte hypertrophy.

Poly(N-isopropylacrylamide) hydrogels with interpenetrating multiwalled carbon nanotubes for cell sheet engineering.

Hydrogels have been developed as artificial extracellular matrixes (ECMs) to mimic native tissue microenvironments for various applications. Unfortunately, poly(N-isopropylacrylamide) (PNIPAAM)-based hydrogels are not suitable for cell culturing and cell sheet preparation. Carbon nanotubes (CNTs), with their mechanical strength and electrical conductivity, have been considered as additives to increase the applicability of hydrogels to cell encapsulation and advance cardiac electrophysiological functions. A simple method for fabrication of PNIPAAM hydrogels interpenetrated with multiwalled CNTs (MWCNTs) as substrates for cell sheet preparation is reported. The results demonstrate that PNIPAAM hydrogels with interpenetrating MWCNTs still exhibit thermosensitive behavior. It is also found that epithelial Madin-Darby canine kidney (MDCK) cells can only attach and proliferate on MWCNT-interpenetrated PNIPAAM hydrogels. Furthermore, the PNIPAAM hydrogels with MWCNTs possess higher elastic moduli and hydrophobicities than those without MWCNTs, suggesting these two characteristics are necessary for the cells to attach to the hydrogel surfaces. Moreover, cell sheets can only be harvested from PNIPAAM hydrogels with MWCNTs because of their high ratio of cell attachment. Thus, this simple method provides sufficient mechanical strength to PNIPAAM hydrogels so that anchorage-dependent cells can be cultivated and provides a superior system for preparing cell sheets.

Statins initiated after hypertrophy inhibit oxidative stress and prevent heart failure in rats with aortic stenosis.

OBJECTIVE: Heart failure is a major and escalating public health problem. Recent studies have demonstrated that statins prevented chronic heart failure (CHF) in animal studies. However, it is unknown whether statins therapy initiated after left ventricular (LV) hypertrophy is evident can still effectively prevent CHF. This study tested the hypothesis that statins can prevent the transition of hypertrophy to heart failure. METHODS AND RESULTS: The rats were studied at 6, 12, and 20 weeks after aortic stenosis (AS) operation. Some rats were given simvastatin (2.0 mg kg(-1) per day) from 13 weeks after AS operation for 8 weeks. Coarctation of aorta in rats resulted in compensatory LV hypertrophy (LVH), concomitant with an increase of superoxide levels and cardiomyocyte apoptosis in LV tissues at 12 weeks after AS operation. This was followed by CHF with a progressive increase in superoxide levels and cardiomyocyte apoptosis in LV tissues at 20 weeks after AS operation. Simvastatin treatment initiated from 13 weeks after AS operation significantly improved LV function and reduced superoxide levels and cardiomyocyte apoptosis in LV tissues. Pretreatment of simvastatin suppressed the hydrogen peroxide-induced apoptosis of cultured cardiomyocytes from neonatal rats. CONCLUSIONS: These data indicate that long-term administration of simvastatin improved LV function and prevented the transition of hypertrophy to CHF. Inhibition of oxidative stress and cardiomyocyte apoptosis may contribute to the benefits of simvastatin treatment on heart of rats with AS.