RESUMO
During drug discovery, small molecules are typically assayed in vitro for secondary pharmacology effects, which include ion channels relevant to cardiac electrophysiology. Compound A was an irreversible inhibitor of myeloperoxidase investigated for the treatment of peripheral artery disease. Oral doses in dogs at ≥5 mg/kg resulted in cardiac arrhythmias in a dose-dependent manner (at Cmax, free ≥1.53 µM) that progressed in severity with time. Nevertheless, a panel of 13 different cardiac ion channel (K, Na, and Ca) assays, including hERG, failed to identify pharmacologic risks of the molecule. Compound A and a related Compound B were evaluated for electrophysiological effects in the isolated rabbit ventricular wedge assay. Compounds A and B prolonged QT and Tp-e intervals at ≥1 and ≥.3 µM, respectively, and both prolonged QRS at ≥5 µM. Compound A produced early after depolarizations and premature ventricular complexes at ≥5 µM. These data indicate both compounds may be modulating hERG (Ikr) and Nav1.5 ion channels. In human IPSC cardiomyocytes, Compounds A and B prolonged field potential duration at ≥3 µM and induced cellular dysrhythmia at ≥10 and ≥3 µM, respectively. In a rat toxicology study, heart tissue: plasma concentration ratios for Compound A were ≥19X at 24 hours post-dose, indicating significant tissue distribution. In conclusion, in vitro ion channel assays may not always identify cardiovascular electrophysiological risks observed in vivo, which can be affected by tissue drug distribution. Risk for arrhythmia may increase with a "trappable" ion channel inhibitor, particularly if cardiac tissue drug levels achieve a critical threshold for pharmacologic effects.
Assuntos
Arritmias Cardíacas , Células-Tronco Pluripotentes Induzidas , Miócitos Cardíacos , Animais , Miócitos Cardíacos/efeitos dos fármacos , Cães , Humanos , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Coelhos , Arritmias Cardíacas/induzido quimicamente , Masculino , Ventrículos do Coração/efeitos dos fármacos , Canais Iônicos/metabolismo , FemininoRESUMO
This study investigated the effects and mechanisms of total saponins of Panax japonicus(TSPJ) against liver injury induced by acetaminophen(APAP). Male Kunming mice were randomly divided into a blank control group, TSPJ group(200 mg·kg~(-1), ig), model group, APAP+ TSPJ low-dose group(50 mg·kg~(-1), ig), APAP+ TSPJ medium-dose group(100 mg·kg~(-1), ig), APAP+ TSPJ high-dose group(200 mg·kg~(-1), ig), and APAP+ N-acetyl-L-cysteine group(200 mg·kg~(-1), ip). The administration group received the corresponding medications via ig or ip once a day for 14 consecutive days. After the last administration for one hour, except for the blank control group and TSPJ group, all groups of mice were given 500 mg·kg~(-1) APAP by gavage. After 24 hours, mouse serum and liver tissue were collected for serum alanine aminotransferase(ALT), aspartate aminotransferase(AST), reactive oxygen species(ROS), tumor necrosis factor alpha(TNF-α), interleukin-1 beta(IL-1ß), cyclooxygenase-2(COX-2), IL-6, IL-4, IL-10, as well as lactate dehydrogenase(LDH), glutathione(GSH), superoxide dismutase(SOD), catalase(CAT), total antioxidant capacity(T-AOC), malondialdehyde(MDA), and myeloperoxidase(MPO) liver tissue. Hematoxylin-eosin staining was used to observe the morphological changes of liver tissue. The mRNA expression levels of lymphocyte antigen 6G(Ly6G), galectin 3(Mac-2), TNF-α, IL-1ß, COX-2, IL-6, IL-4, and IL-10 in liver tissue were determined by quantitative real-time polymerase chain reaction(PCR). Western blot was utilized to detect the protein expression levels of Ly6G, Mac-2, extracellular regulated protein kinases(ERK), phosphorylated extracellular regulated protein kinases(p-ERK), COX-2, inhibitor of nuclear factor κB protein α(IκBα), phosphorylated inhibitor of nuclear factor κB protein α(p-IκBα), and nuclear factor-κB subunit p65(NF-κB p65) in cytosol and nucleus in liver tissue. The results manifested that TSPJ dramatically reduced liver coefficient, serum ALT, AST, ROS, TNF-α, IL-1ß, IL-6, and COX-2 levels, LDH, MPO, and MDA contents in liver tissue, and mRNA expressions of TNF-α, IL-1ß, and IL-6 in APAP-induced liver injury mice. It prominently elevated serum IL-4 and IL-10 levels, GSH, CAT, SOD, and T-AOC contents, and mRNA expressions of IL-4 and IL-10 in liver tissue, improved the degree of liver pathological damage, and suppressed neutrophil infiltration and macrophage recruitment in liver tissue. In addition, TSPJ lessened the mRNA and protein expressions of neutrophil marker Ly6G, macrophage marker Mac-2, and COX-2 in liver tissue, protein expressions of p-ERK, p-IκBα, and NF-κB p65 in nuclear, and p-ERK/ERK and p-IκBα/p-IκBα ratios and hoisted protein expression of NF-κB p65 in cytosol. These results suggest that TSPJ has a significant protective effect on APAP-induced liver injury in mice, and it can alleviate APAP-induced oxidative damage and inflammatory response. Its mechanism may be related to suppressing ERK/NF-κB/COX-2 signaling pathway activation, thus inhibiting inflammatory cell infiltration, cytokine production, and liver cell damage.
Assuntos
Acetaminofen , Doença Hepática Induzida por Substâncias e Drogas , Ciclo-Oxigenase 2 , Fígado , NF-kappa B , Panax , Saponinas , Transdução de Sinais , Animais , Acetaminofen/efeitos adversos , Acetaminofen/toxicidade , Camundongos , Panax/química , Masculino , Saponinas/farmacologia , Saponinas/administração & dosagem , NF-kappa B/genética , NF-kappa B/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Transdução de Sinais/efeitos dos fármacos , Humanos , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/farmacologiaRESUMO
The objective of this study was to extract low frequency respiratory "artifacts" from a standard arterial blood pressure (ABP) waveform to simultaneously derive reliable breathing rates (BR). Arterial blood pressure derived BR values were characterized against respiratory rates simultaneously obtained from the Respiratory Inductive Plethysmography (RIP) system (EMKA). Reference compounds were introduced to evaluate responsiveness of the derived measures to respiratory depressants and stimulants. Male beagle dogs (n = 3) were instrumented with minimally invasive telemetry devices for measurements of ABP and heart rate. The RIP system was utilized simultaneously to collect respiratory rate, tidal volume, and minute volume of each animal following pharmacological challenges. Early results revealed the derived BR's from ABP waveforms did not correlate well with those measured from the RIP system. Post study X-ray visualization revealed suboptimal catheter positioning, causing poor concordance of BR tallied from the ABP waveforms. Follow-up evaluations were conducted using additional animals instrumented with the ABP catheter tip placement advanced proximal to the thoracic diaphragm. Preliminary data from this subset of animals significantly improved the correlation of BR derived from ABP and respiratory rates recorded by the RIP. This proof of concept investigation was intended to evaluate an algorithm designed to extract additional data from routine cardiac waveforms. We clearly demonstrated that with optimal blood pressure catheter placement and acquisition algorithm, a reliable breathing rate can also be extracted from safety studies without the need for additional studies/animals to capture those respiratory end points.
Assuntos
Pressão Sanguínea/fisiologia , Dexmedetomidina/farmacologia , Monitorização Fisiológica/métodos , Taxa Respiratória/fisiologia , Teofilina/farmacologia , Agonistas de Receptores Adrenérgicos alfa 2/farmacologia , Animais , Cães , Masculino , Antagonistas de Receptores Purinérgicos P1/farmacologiaRESUMO
Drug-induced cardiotoxicity, including tachycardia and QT prolongation, remains a major safety concern that needs to be identified and its risk mitigated in early stages of drug development. In the present study, an integrated toxicokinetic-toxicodynamic (TK-TD) modeling approach within a nonlinear mixed-effect modeling framework is applied to investigate concurrent abnormal heart rate and QT changes in three beagle dogs, using a Novartis internal compound (NVS001) as the case example. By accounting for saturable drug absorption, circadian rhythms, drug-effect tolerance, and nonlinear rate-dependency of QT interval, the dynamic TK-TD model captures the experimentally observed drug effects on heart rate and QT interval across a wide dosing range of NVS001 in beagle dogs. Further analyses reveal that the NVS001-induced QT prolongation observed in the low-dose groups is potentially caused by direct drug inhibition on the hERG channel, while the apparent QT shortening in the high-dose groups may be due to strong rate-dependency of QT at high heart rates. This study also suggests that the TK-TD model can be used to identify direct drug effects on the non-rate-dependent QT component by dissociating QT changes from tachycardia and deriving a new QT correction method. The integrated TK-TD model presented here may serve as a novel quantitative framework for evaluating drug-induced concurrent changes in heart rate and QT to potentially facilitate preclinical and clinical safety studies.
Assuntos
Eletrocardiografia/efeitos dos fármacos , Modelos Biológicos , Taquicardia/induzido quimicamente , Acetatos/farmacologia , Animais , Cães , Relação Dose-Resposta a Droga , Masculino , Dinâmica não Linear , Tiazóis/farmacologiaRESUMO
This research established an HPLC method for determination of six C-Glycoside flavones of warer-soluble total flavonoids from Isodon lophanthoides var. gerardianus (Benth.) H. Hara, and studied the antitumor activity of the warer-soluble total flavonoids. The HPLC system consisted of Kromasil 100-5 C18 (4.6 mm x 250 mm, 5 microm) column and a solution system of methanol, acetonitrile and 0.5% formic acid gradient elution at a flow rate of 0. 8 mL x min(-1) and the wavelength of detector was at 334 nm. The column temperature was 25 degrees C. The antitumor activity of water-soluble flavonoids was assayed using HepG2 cell as the tested cell. The linear ranges of vicenin II, vicenin III, isoschaftoside, schaftoside, vitexin, 6, 8-di-C-a-L-arabinosylapigenin were 0.25-2.53, 0.12-1.20, 0.37-3.69, 0.16-1.63, 0.19-1.92, 0.14-1.42 microg, respectively. The average recoveries (n = 6) were 99.6% (RSD 0.87%), 100.2% (RSD 2.0%), 99.6% (RSD 1.8%), 97.9% (RSD 1.5%), 98.8% (RSD 1.2%), 98.6% (RSD 1.2%), respectively. After exposure in 24, 48, 72 h, the total flavonoids showed inhibitory effect on the proliferation of HepG2 cells with IC50 as the evaluation index, the IC50 values of 1.89, 1.71, 1.51 g x L(-1), respectively. The method is quick, simple and accurate with good re- producibility, and can be used for determination of vicenin II, vicenin III, isoschaftoside, schaftoside, vitexin, 6, 8-di-C-a-L-arabino- sylapigenin in the warer-soluble total flavonoids from L lophanthoides var. gerardianus. The warer-soluble total flavonoids from L lophanthoides have inhibitory effect on the proliferation of HepG2 cells.
Assuntos
Antineoplásicos Fitogênicos/análise , Medicamentos de Ervas Chinesas/análise , Flavonas/análise , Isodon/química , Monossacarídeos/análise , Antineoplásicos Fitogênicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Medicamentos de Ervas Chinesas/farmacologia , Flavonas/farmacologia , Glicosídeos , Humanos , Monossacarídeos/farmacologiaRESUMO
INTRODUCTION: Cardiovascular safety and the risk of developing the potentially fatal ventricular tachyarrhythmia, Torsades de Pointes (TdP), have long been major concerns of drug development. TdP is associated with a delayed ventricular repolarization represented by QT interval prolongation in the electrocardiogram (ECG), typically due to block of the potassium channel encoded by the human ether-a-go-go related gene (hERG). Importantly however, not all drugs that prolong the QT interval are torsadagenic and not all hERG blockers prolong the QT interval. Recent clinical reports suggest that partitioning the QT interval into early (J to T peak; JTp) and late repolarization (T peak to T end; TpTe) components may be valuable for distinguishing low-risk mixed ion channel blockers (hERG plus calcium and/or late sodium currents) from high-risk pure hERG channel blockers. This strategy, if true for nonclinical animal models, could be used to de-risk QT prolonging compounds earlier in the drug development process. METHODS: To explore this, we investigated JTp and TpTe in ECG data collected from telemetered dogs and/or monkeys administered moxifloxacin or amiodarone at doses targeting relevant clinical exposures. An optimized placement of the Tpeak fiducial mark was utilized, and all intervals were corrected for heart rate (QTc, JTpc, TpTec). RESULTS: Increases in QTc and JTpc intervals with administration of the pure hERG blocker moxifloxacin and an initial QTc and JTpc shortening followed by prolongation with the mixed ion channel blocker amiodarone were detected as expected, aligning with clinical data. However, anticipated increases in TpTec by both standard agents were not detected. DISCUSSION: The inability to detect changes in TpTec reduces the utility of these subintervals for prediction of arrhythmias using continuous singlelead ECGs collected from freely moving dogs and monkeys.
Assuntos
Amiodarona , Eletrocardiografia , Síndrome do QT Longo , Moxifloxacina , Torsades de Pointes , Animais , Moxifloxacina/administração & dosagem , Moxifloxacina/farmacologia , Cães , Amiodarona/administração & dosagem , Amiodarona/farmacologia , Eletrocardiografia/efeitos dos fármacos , Eletrocardiografia/métodos , Torsades de Pointes/induzido quimicamente , Síndrome do QT Longo/induzido quimicamente , Síndrome do QT Longo/fisiopatologia , Masculino , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Canais de Potássio Éter-A-Go-Go/metabolismo , Feminino , Macaca fascicularis , Fluoroquinolonas/administração & dosagem , Fluoroquinolonas/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/administração & dosagem , Bloqueadores dos Canais de Potássio/farmacologia , Canal de Potássio ERG1/antagonistas & inibidores , Canal de Potássio ERG1/metabolismoRESUMO
INTRODUCTION: Characterization of the incidence of spontaneous arrhythmias to identify possible drug-related effects is often an important part of the analysis in safety pharmacology studies using telemetry. METHODS: A retrospective analysis in non-clinical species with and without telemetry transmitters was conducted. Electrocardiograms (24 h) from male and female beagle dogs (n = 131), Göttingen minipigs (n = 108) and cynomolgus non-human primates (NHP; n = 78) were analyzed. RESULTS: Ventricular tachycardia (VT) was observed in 3% of the dogs but was absent in minipigs and NHPs. Ventricular fibrillation (VF) was not observed in the 3 species. Ventricular premature beats (VPBs) were more frequent during daytime and atrioventricular blocks (AVBs) were more frequent at night in all species. A limited number of animals exhibited a high arrhythmia frequency and there was no correlation between animals with higher frequency of an arrhythmia type and the frequency of other arrythmias in the same animals. Clinical chemistry or hematology parameters were not different with or without telemetry devices. NHP with a transmural left ventricular pressure (LVP) catheter exhibited a greater incidence of VPBs and PJCs compared to telemetry animals without LVP. DISCUSSION: All species were similar with regards to the frequency of ventricular ectopic beats (26-46%) while the dog seemed to have more frequent junctional complexes and AVB compared to NHP and minipigs. Arrhythmia screening may be considered during pre-study evaluations, to exclude animals with abnormally high arrhythmia incidence.
Assuntos
Arritmias Cardíacas , Telemetria , Animais , Cães , Suínos , Masculino , Feminino , Porco Miniatura , Incidência , Estudos Retrospectivos , EletrocardiografiaRESUMO
MicroRNAs (miRNAs) are a class of ~22nt long non-coding RNAs. They are evolutionarily conserved and play essential roles in the regulation of post-transcriptional gene expression. The rapidly developing next generation sequencing (NGS) has important applications in miRNA detection. This review is focused on the mechanism of three NGS platforms and their applications in miRNA detection. In contrast to traditional methods, NGS has major advantages: high throughput, precise, accurate, and repeatable. Its application includes new miRNAs exploration, detection of miRNA*, miRNA editing, and isomiR and target mRNA detection. As NGS develops, the cost of sequencing is declining which makes it possible for NGS to be widely used in the coming years. Next generation sequencing will greatly promote researches of miRNAs.
Assuntos
MicroRNAs/química , MicroRNAs/genética , Análise de Sequência de RNA/métodos , Edição de RNA/genética , RNA Mensageiro/genéticaRESUMO
To clarify the impacts of long-term different fertilization modes on the soil acid hydrolysable organic nitrogen and its components in the double-cropping rice field of southern China, a long-term (36-year) location field experiment was used as a platform to systematically analyze the variations of soil acid hydrolysable organic nitrogen and its components (amino acid nitrogen, amino sugar nitrogen, ammonium nitrogen, unidentified hydrolysable nitrogen) at 0-10 cm and 10-20 cm soil layers under four fertilization treatments, including chemical fertilizer alone (CF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and control (CK). The relationships of soil acid hydrolysable organic nitrogen content and soil total nitrogen, soil organic carbon content were also analyzed. The results showed that compared with CK, OM and RF treatments significantly increased the contents of total nitrogen, available nitrogen, and organic carbon at both soil layers. The contents of soil acid hydrolysable organic nitrogen at 0-10 cm and 10-20 cm layers of OM, RF and CF treatments were 10.7%-42.6% and 12.2% -51.5% higher than that of CK, respectively. Compared with CF and CK treatments, OM and RF treatments significantly increased the contents of amino acid nitrogen, ammonium nitrogen, unidentified hydrolysable nitrogen and amino sugar nitrogen contents atboth soil layers. The soil acid hydrolysable organic nitrogen and non-hydrolysable nitrogen contents at 0-10 cm and 10-20 cm paddy soils under different fertilization treatments decreased in an order of OM>RF>CF>CK. The contents of soil amino acid nitrogen, ammonium nitrogen, amino sugar nitrogen and non-hydrolysable nitrogen at 0-10 cm soil layer of each fertilization treatment were higher than those at 10-20 cm soil layer. In addition, the contents of soil acid hydrolyzed organic nitrogen were positively correated with the contents of soil total nitrogen and soil organic carbon. In conclusion, RF and OM treatments were beneficial to increase organic nitrogen content at 0-10 and 10-20 cm soil layers of double cropping paddy fields, with postive consequences on nitrogen supply capacity and soil fertility.
Assuntos
Oryza , Solo , Solo/química , Oryza/química , Nitrogênio/análise , Fertilizantes/análise , Carbono/análise , Aminoácidos , China , Esterco , Fertilização , Agricultura/métodosRESUMO
There is close relationship between fertilizer managements and net carbon (C) sink effect, economic benefits in rice paddy ecosystem. Based on a long-term (35-year) field experiment, we analyzed the effects of different fertilization patterns on soil C sequestration rate, C density of topsoil, annual C balance, and economic benefits in the double cropping rice paddy in southern China. There were four fertilization treatments, chemical fertilizer alone (MF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without any fertilizer input as a control (CK). The results showed that soil C pool in the double cropping rice paddy field under different fertilization treatments changed from 216.02 to 866.74 kg·hm-2·a-1, and soil C pool under OM treatment were significantly higher than that of MF, RF and CK. The soil C sequestration rates in the double cropping rice paddy field under different fertilization treatments ranged from 51.5 to 650.7 kg·hm-2·a-1, and that of C density of topsoil was from 55.64 to 78.42 t·hm-2. The order of soil C sequestration rates and C density of topsoil was OM>RF>MF>CK. The change range of C adsorption in the double cropping rice paddy field ecosystem was from 4.42 to 9.32 t C·hm-2·a-1, with an order of OM>RF>MF>CK. Compared with the MF treatment, soil net C sink under OM and RF treatments increased by 27.6% and 13.6%, respectively. The change range of C cost material input ranged from 1.49 to 2.17 t C·hm-2·a-1, and that of annual economic benefits was from 1.30×103 to 7.83×103 yuan·hm-2·a-1 with an order of RF>OM>MF>CK. The net income of economic benefits of OM, RF and MF treatments were significantly higher than that of CK. Generally, soil C sequestration rate, C sink effect and annual economic benefits were increased by the long-term application of organic manure and rice straw returning together with chemical fertilizer, which could increase soil organic carbon storage in the double cropping rice paddy field of southern China.
Assuntos
Fertilizantes , Oryza , Agricultura/métodos , Carbono/análise , Sequestro de Carbono , China , Ecossistema , Fertilização , Fertilizantes/análise , Esterco/análise , SoloRESUMO
The cholesterol metabolism in humans can be indirectly reflected by measuring cholesterol metabolism marker levels. We aimed to investigate the association of cholesterol homeostasis markers on standard lipid profiling components in familial hypercholesteremia and hyperlipidemia patients. A total of 69 hyperlipidemia patients, 25 familial hypercholesteremia (FHC) patients, and 64 healthy controls were enrolled in this study. We performed routine testing of blood lipid water. Gas chromatography was used to determine the changes in the concentration of cholesterol synthesis (squalene, desmosterol, and lathosterol) and absorption markers (campesterol, sitosterol, and stigmasterol) in the blood. Baseline hyperlipidemia patients displayed significantly higher total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels in comparison to the control group, which was reflected in the increased levels of squalene, desmosterol, campesterol, and sitosterol observed (P < 0.05) in the hyperlipidemia patients. The desmosterol, lathosterol, campesterol, stigmasterol, and sitosterol were statistically different in the FHC group than the hyperlipidemic group (P < 0.05). The proportions of squalene/cholesterol, lathosterol/cholesterol, stigmasterol/cholesterol, and sitosterol/cholesterol in the FHC group were lower than those in the hyperlipidemic group; only desmosterol/cholesterol was higher than that in the hyperlipidemic group. Correlation studies between lipid metabolic factors showed that the proportion of moderate and strong correlations was much higher in the FHC group than in the other two groups (76.92% vs. 32.50% and 31.25%). Logistic regression analysis showed that the concentrations of glucose, LDL-C, lactosterol, and sitosterol were all independent risk factors for developing hyperlipidemia. This result was further confirmed by the ROC curve. These results indicated that the study of cholesterol synthesis and decomposition markers can serve as a reference index for related diseases caused by changes in its concentration.
Assuntos
Hipercolesterolemia , Hiperlipidemias , Hiperlipoproteinemia Tipo II , Colesterol , LDL-Colesterol , Desmosterol , Humanos , Hiperlipoproteinemia Tipo II/diagnóstico , Lipídeos , Sitosteroides , Esqualeno , EstigmasterolRESUMO
BACKGROUND/AIMS: Monitoring changes in the field potential (FP) of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) following compound administration has been proposed as a novel screening tool to evaluate cardiac ion channel interactions and QT liability. Here we extended the use of FP to evaluate the pharmacological and toxicological properties of cardiac glycosides. METHODS: FPs were recorded using microelectrode arrays (MEAs) in spontaneously beating hiPSC-CMs. The in vitro effects of ouabain and digoxin on FPs were compared with data generated on hemodynamic and ECG parameters in guinea pig Langendorff hearts. RESULTS: In hiPSC-CMs, ouabain and digoxin reduced Na(+)-spike amplitude, shortened FP duration (FPD), increased Ca(2+)-wave amplitude, and dose-dependently induced arrhythmic beats. The ouabain-induced changes observed in hiPSC-CMs correlated well with the effects seen in isolated hearts which revealed QT shortening, enhancement of contractility, and arrhythmogenesis. Nifedipine, an L-type Ca(2+) channel blocker, reduced Ca(2+)-wave amplitude and FPD in hiPSC-CMs, and led to parallel effects of decreased ventricular contractility and shortened QT interval in isolated hearts. Further, nifedipine attenuated the Ca(2+)-peak amplitude and proarrhythmic effect of both glycosides. These results suggested that FPD and Ca(2+)-wave amplitude are comparable surrogates of QT interval and contractility of intact hearts, respectively. CONCLUSION: hiPSC-CMs reflect similar cardiac pharmacology as seen in isolated cardiac preparations and thus are a suitable model in study of the pharmacology and toxicology of cardioactive ion channel and transporter modulators.
Assuntos
Canais de Cálcio/efeitos dos fármacos , Cálcio/metabolismo , Glicosídeos Cardíacos/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Contração Miocárdica/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/fisiologia , Potenciais de Ação , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/fisiologia , Diferenciação Celular , Células Cultivadas , Digoxina/farmacologia , Relação Dose-Resposta a Droga , Eletrocardiografia , Cobaias , Hemodinâmica , Humanos , Microeletrodos , Miócitos Cardíacos/citologia , Nifedipino/farmacologia , Técnicas de Cultura de Órgãos , Ouabaína/farmacologia , Células-Tronco Pluripotentes/citologiaRESUMO
Fertilization is an effective way to improve soil quality, increase soil fertility and soil microbial diversity in paddy soil. To explore the changes of soil labile organic carbon (C) fractions and hydrolytic enzyme activity after 34 years fertilization treatments in a field experiment in double-cropping rice system of southern China. There were four treatments, including chemical fertilizer alone (MF), rice residue and chemical fertilizer (RF), 30% organic matter and 70% chemical fertilizer (OM), and the control without fertilizer input (CK). We measured soil organic carbon (SOC) content, soil labile organic C fractions, SOC related hydrolytic enzyme activity, correlation coefficients of soil enzyme activity with SOC content and its labile organic C fractions. The results showed that MF, RF and OM increased SOC content by 4.5%, 22.4% and 53.5%, respectively. Compared with MF and CK, RF and OM increased soil labile organic C fractions [cumulative C mineralization (Cmin), permanganate oxidizable C (KMnO4-C), particulate organic C (POC), dissolved organic C (DOC), light fraction organic C (LFOC), microbial biomass C (MBC)] and the proportion of each labile organic C fractions to total organic C. The contents of Cmin, KMnO4-C, POC, DOC, LFOC and MBC under OM treatment were 3.5, 3.1, 3.7, 1.9, 1.2 and 1.9 times higher than CK treatment, respectively. The proportion of labile organic C fractions to total organic C of RF and OM treatments was significantly higher than that in CK. The order of soil hydrolytic enzyme activity [α-glucosidase (αG), ß-glucosidase (ßG), ß-xylosidase (ßX), cellobiohydrolase (GBH), and N-acetyl-ß-glucosaminidase (NAG)] was OM>RF>MF>CK. The soil hydrolytic enzyme activity under OM treatment increased by 111.8%, 14.1%, 127.3%, 285.6% and 91.4% compared with CK, respectively. Furthermore, RF and OM treatments were beneficial to soil peroxidase (POD) activity. MF treatment was beneficial to soil polyphenol oxidase (PPO) activity. There was a significant positive correlation between soil hydrolytic enzyme activity and SOC content and its labile organic C fractions. In conclusion, the combined application of organic manure, rice straw returning and chemical fertilizer is an effective method to improve soil labile organic C fractions and hydrolytic enzyme activity in a double-cropping rice paddy field of southern China.
Assuntos
Fertilizantes , Oryza , Agricultura , Carbono/análise , China , Fertilizantes/análise , SoloRESUMO
INTRODUCTION: Alterations in cardiac contractility can have significant clinical implications, highlighting the need for early detection of potential liabilities. Pre-clinical methods to assess contractility are typically invasive and their translation to human measures of cardiac function are not well defined. Clinically, cardiac function is most often measured non-invasively using echocardiography. The objective of these studies was to introduce echocardiography into standard large animal cardiovascular safety pharmacology studies and determine the feasibility of this combination. METHODS: A consortia of laboratories combined their data sets for evaluation. At each site, telemetered beagle dogs, in a 4 × 4 Latin square crossover study design (n = 4), were administered either pimobendan (positive inotrope) or atenolol (negative inotrope) orally at clinically relevant dose levels. Standard telemetry parameters were collected (heart rate, mean arterial blood pressure, etc.) continuously over 24 h, as well as derived contractility endpoints: QA interval and LV +dP/dtmax. At Tmax, echocardiography was performed in conscious dogs with minimal restraint to collect contractility parameters: ejection fraction (EF) and fractional shortening (FS). RESULTS: Correlations between telemetry and echo contractility endpoints showed that, in general, a change in LV +dP/dtmax of 1000 mmHg/s translates to a 5.2% change in EF and a 4.2% change in FS. Poor correlations were shown between QA interval derived simultaneously, to both EF and FS. DISCUSSION: Comparing data from telemetry-only groups to those that included echocardiography collections showed no effect in the ability to interpret test article-related effects, providing the foundation for the inclusion of echocardiography without compromising standard telemetry data quality.
Assuntos
Cardiotônicos/efeitos adversos , Hemodinâmica/efeitos dos fármacos , Contração Miocárdica/efeitos dos fármacos , Animais , Atenolol/efeitos adversos , Pressão Sanguínea/efeitos dos fármacos , Estudos Cross-Over , Cães , Ecocardiografia/métodos , Eletrocardiografia/métodos , Feminino , Frequência Cardíaca/efeitos dos fármacos , Masculino , Piridazinas/efeitos adversos , Telemetria/métodos , Função Ventricular Esquerda/efeitos dos fármacosRESUMO
To investigate the effects of different planting patterns on soil nutrient contents, rice yield, nitrogen production efficiency, and apparent nutrient balance, a long-term field experiment was conducted in Changsha, Hunan, China. Four planting patterns were examined, including winter fallow-double cropping rice (CK), ryegrass-double cropping rice (Ry-R-R), Chinese milk vetch-double cropping rice (Mv-R-R), rape-double cropping rice (Ra-R-R). Compared with CK, soil total nitrogen (N) and available N were significantly higher under Ry-R-R, Mv-R-R and Ra-R-R. However, soil available potassium (K) content in CK was significantly higher than that in the other treatments. In addition, the N partial factor productivity in the late rice cropping was significantly higher under Ry-R-R, Mv-R-R and Ra-R-R. The N accumulation in panicles, stems and leaves of late rice under Ry-R-R, Mv-R-R and Ra-R-R were significantly higher than that in CK. Furthermore, the rice yield in Ry-R-R and Mv-R-R were significantly higher in comparison to CK. A significant positive correlation between grain yield and soil N content was observed. Compared with CK, Ry-R-R and Mv-R-R significantly increased the surplus of soil N and phosphorus content, but Ry-R-R and Ra-R-R increased the surplus of K content. Overall, winter crop-double rice cropping system could improve soil nutrient contents and N production efficiency, alleviate K deficiency, which would be beneficial to soil nutrient balance of paddy soils. Given the high surplus of N in paddy soils, N fertilizers should be reduced.
Assuntos
Agricultura/métodos , Oryza , China , Fertilizantes , Nitrogênio/análise , Fósforo/análise , Solo/química , Microbiologia do SoloRESUMO
To explore the characteristics of rhizosphere soil microorganisms in paddy fields with different manure nitrogen (N) input ratios at different growth stages of early and late rice in double-cropping rice system, a field experiment was conducted with five different treatments: 1) 100% N of chemical fertilizer (M1), 2) 30% N of organic matter and 70% N of chemical fertilizer (M2), 3) 50% N of organic matter and 50% N of chemical fertilizer (M3), 4) 100% N of organic matter (M4), and 5) no N fertilizer input as a control (M0). The rhizosphere soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial quotient (SQ) of the paddy fields were measured using the fumigation-extraction and chemical analysis methods. The results showed that the rhizosphere MBC, MBN, and SQ of the paddy fields at main different growth stages of early and late rice were increased by fertilization, which increased first and then decreased with the development of rice growth period, peaked at the heading stage, and reached the minimum value at the maturity stage. The effects of different fertilization treatments were in order of M4ï¼M3ï¼M2ï¼M1ï¼M0, with no significant difference among M2, M3 and M4, but being significantly higher than M0. Therefore, the application of organic matter, and combined application of chemical fertilizer with organic matter could significantly increase the rhizosphere MBC, MBN, and SQ of the paddy fields at early and late rice growth period, while chemical fertilizer alone had little effect.
Assuntos
Agricultura/métodos , Esterco , Microbiologia do Solo , Solo , Biomassa , Carbono/análise , Fertilizantes , Nitrogênio/análise , Oryza , RizosferaRESUMO
Rhizosphere and non-rhizosphere soil samples under different long-term fertilization treatments including control without fertilizer (CK), chemical fertilization alone (NPK), rice residues combined with NPK (NPKS), 30% manure plus 70% chemical fertilizers (LOM), and 60% manure plus 40% chemical fertilizers (HOM) were collected from a paddy field in a red soil hilly area in Ningxiang City, Hunan Province, China. The characteristics of microbial carbon utilization in the soils were studied. Results of 18O-H2O tracer analysis showed that both soil microbial biomass carbon content (MBC) and microbial growth rate (CGrowth) were highest in the HOM treatment, whereas they were lowest in CK. In the rhizosphere soil, the highest basal respiration was observed in HOM, and the lowest values were in CK and NPK. Microbial carbon utilization efficiency (CUE) was highest in NPK but lowest in the LOM and HOM treatments. In non-rhizosphere soil, no significant differences between basal respiration and CUE were observed among the fertilization treatments. Results from MicroRespTM showed that the ability of microorganisms to metabolize exogenous carbon sources was higher in non-rhizosphere soil than in rhizosphere soil. The application of organic materials (rice residues or manure) increased the microbial metabolic rate of carboxylic acids, amino acids, and carbohydrates in the order carboxylic acids > amino acids and carbohydrates > complex compounds. Redundancy analysis of the microbial metabolism patterns of various carbon substrates showed that:â CK was well separated from the fertilization treatments; â¡ NPK was grouped with NPKS, whereas LOM and HOM were grouped together and were separate from NPK and NPKS. This indicates that the fertilization treatments changed the microbial carbon metabolism patterns. The above-mentioned results indicated that the fertilization treatments did not affect microbial CUE and basal respiration. However, exogenous carbon source input (such as root exudates) and the application of organic materials can increase microbial basal respiration, and thus, reduce microbial CUE.
Assuntos
Carbono/química , Metaboloma , Oryza , Rizosfera , Microbiologia do Solo , Solo/química , China , Fertilizantes , EstercoRESUMO
Soil samples were collected from paddy ecosystem under five long-term fertilization treatments, including control without fertilizer (CK), chemical fertilization alone (NPK), rice residue combined with NPK (NPKS), 30% manure plus 70% chemical fertilizer (LOM), and 60% manure plus 40% chemical fertilizer (HOM) in Ningxiang City, Hunan Province. The cha-racteristics of amino sugars accumulation in the rhizosphere and non-rhizosphere soils at rice tillering stage were analyzed. Results showed that the contents of soil organic carbon, total amino sugars and three amino monosaccharides (muramic acid, glucosamine and galactosamine) with long-term application of organic materials (rice residue or manure) were significantly higher compared with CK and NPK. The inconsistent accumulation trends of the three amino monosaccharides under different fertilization treatments indicated that different responses of microbial groups to various fertilization treatments. The content of total amino sugars was not significantly different between the rhizosphere soil and the non-rhizosphere soil, probably because the agricultural operations such as plowing could homogenize paddy soils. The contribution of amino sugar derived carbon to soil organic carbon ranged from 24.0 to 28.3 mg·g-1, which was highest in NPKS, and lowest in HOM and CK. The ratio of fungal to bacterial residues (fungal glucosamine/muramic acid) ranged from 24.4 to 36.6, indicating that fungi dominated the degradation and transformation of organic matter in all the soils. Compared with that under NPK and CK, the participation of organic matter transformation from fungi under NPKS treatment was increased, whereas the bacteria involved in organic matter transformation under HOM treatment was enhanced.
Assuntos
Amino Açúcares/metabolismo , Fertilizantes , Oryza/fisiologia , Rizosfera , SoloRESUMO
Four paddy soils were collected in Ningxiang County, Hunan province. These used with different long-term fertilization regimes, including a control without fertilizer (CK), chemical fertilization with nitrogen, phosphate, and kalium (NPK), straw fertilization combined with NPK (ST), and manure fertilization combinedwith NPK (OM). Phospholipid fatty acid (PLFA) technology and MicrorespTM method were used to study the effect of long-term fertilization on soil microorganism abundance, community structure, and activity. Results showed that the abundance of bacteria, fungi, gram-negative (G-) bacteria, and gram-positive (G+) bacteria in the soil from the OM treatment was generally higher than for the other treatments; these levels were lower in the ST and NPK treatments and lowest in the CK treatment. The principal components analysis (PCA) of PLFA showed that the community structure of microorganisms in NPK, ST, and OM treatments was altered in comparison with that in CK, especially in the case of the ST and OM treatments. MicroRespTM results revealed that compared to the CK treatment (1.28 µg·h-1), soil microorganisms in the OM treatment had the highest average utilization rate of multiple carbon sources (1.81 µg·h-1), followed by ST (1.19 µg·h-1), CK (1.28 µg·h-1), and NPK (0.95 µg·h-1). Furthermore, different long-term fertilization regimes resulted in distinct carbon source preferences for the soil microorganisms and revealed a significant alteration in the microbial community. Conclusively, long-term fertilizer with straw or manure changes the microbial community and is a benefit for improving the biomass and activity of microorganism in rice paddy soils.
Assuntos
Biomassa , Fertilizantes , Oryza , Microbiologia do Solo , Agricultura , Esterco , Nitrogênio , Fósforo , Potássio , SoloRESUMO
In a double cropping rice field experiment, effects of five winter cover crops on the total organic carbon (TOC), active organic carbon (AOC), carbon pool management index (CPMI) and organic carbon storage were studied in three soil layers (0-5, 5-10 and 10-20 cm).Winter cover crops of ryegrass (Ry), Chinese milk vetch (Mv), potato (Po), and rape (Ra) between two rice crops were compared with fallow as control (CK). The results showed that the TOC and AOC contents under Ry, Mv, Po and Ra treatments were higher than those of CK in all three la-yers. Meanwhile, the TOC and AOC contents in Po treatment were higher than those of other treatments. Compared with CK, the AOC, activity index (AI), carbon pool index (CPI) and CPMI in the soil were improved through the recycling of winter cover crops straw. The AOC, AI, CPI and CPMI in the studied layers increased in order of Po>Mv>Ry>Ra>CK. The results indicated that the recycling of winter cover crops straw promoted the storage of SOC in the 0-20 cm soil profile as compared with CK. The strongest effect of the winter cover crops on the SOC storage occurred in Mv treatment, followed by Mv and Po treatments, and the SOC storage increased with the increasing soil depth.