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1.
Chirality ; 36(5): e23669, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38747136

RESUMEN

The aim of this study was to investigate the chiral inversion and the stereoselective pharmacokinetic profiles of desmethyl-phencynonate hydrochloride after administration of the single isomer and its racemate to beagle dogs. A liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was established for determination of the stereoisomers on chiral columns in beagle dog plasma, which met all the requirements. The chiral inversion in dogs of the desmethyl-phencynonate hydrochloride were studied after administration of the single isomer or the racemic modification. The stereoselective pharmacokinetic profiles of the desmethyl-phencynonate hydrochloride were studied by assays for simultaneous isomers after administration of the racemic modification. The results showed that the absorption of the R-configuration dosed as the single isomer was higher than it dosed as the racemic modification. The AUC(0-t), AUC(0-∞), and Cmax of the S-configuration were much higher than those of R-configuration after oral administration of the racemic desmethyl-phencynonate hydrochloride. The chiral inversion of desmethyl-phencynonate isomers could not occur in dogs after administration of the R-configuration.


Asunto(s)
Espectrometría de Masas en Tándem , Animales , Perros , Estereoisomerismo , Espectrometría de Masas en Tándem/métodos , Masculino , Cromatografía Liquida/métodos , Administración Oral , Área Bajo la Curva
2.
Soft Matter ; 17(22): 5524-5531, 2021 Jun 09.
Artículo en Inglés | MEDLINE | ID: mdl-33972975

RESUMEN

Elucidating emergent regularities in intriguing crowd dynamics is a fundamental scientific problem arising in multiple fields. In this work, based on the social force model, we simulate the typical scenario of collective escape towards a single exit and reveal the striking analogy of crowd dynamics and crystallisation. With the outflow of the pedestrians, crystalline order emerges in the compact crowd. In this process, the local misalignment and global rearrangement of pedestrians are well rationalized in terms of the characteristic motions of topological defects in the crystal. Exploiting the notions from the physics of crystallisation further reveals the emergence of multiple fast tracks in the collective escape.


Asunto(s)
Aglomeración , Peatones , Humanos , Fenómenos Mecánicos , Modelos Teóricos , Movimiento (Física)
3.
Phys Rev Lett ; 120(24): 248101, 2018 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-29956983

RESUMEN

Dynamics of hydration water is essential for the function of biomacromolecules. Previous studies have demonstrated that water molecules exhibit subdiffusion on the surface of biomacromolecules; yet the microscopic mechanism remains vague. Here, by performing neutron scattering, molecular dynamics simulations, and analytic modeling on hydrated perdeuterated protein powders, we found water molecules jump randomly between trapping sites on protein surfaces, whose waiting times obey a broad distribution, resulting in subdiffusion. Moreover, the subdiffusive exponent gradually increases with observation time towards normal diffusion due to a many-body volume-exclusion effect.


Asunto(s)
Proteínas/química , Agua/química , Sistema Enzimático del Citocromo P-450/química , Difusión , Proteínas Fluorescentes Verdes/química , Modelos Químicos , Simulación de Dinámica Molecular , Difracción de Neutrones
4.
Neural Comput ; 30(11): 3072-3094, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30216145

RESUMEN

We consider Bayesian inference problems with computationally intensive likelihood functions. We propose a Gaussian process (GP)-based method to approximate the joint distribution of the unknown parameters and the data, built on recent work (Kandasamy, Schneider, & Póczos, 2015). In particular, we write the joint density approximately as a product of an approximate posterior density and an exponentiated GP surrogate. We then provide an adaptive algorithm to construct such an approximation, where an active learning method is used to choose the design points. With numerical examples, we illustrate that the proposed method has competitive performance against existing approaches for Bayesian computation.

5.
Biomed Chromatogr ; 31(5)2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-27790733

RESUMEN

A rapid, specific and high-throughput stable isotope-dilution LC-MS/MS method was developed and validated with high sensitivity for the quantification of R-phencynonate (a eutomer of phencynonate racemate) in rat and dog plasma. Plasma samples were deproteinized using acetonitrile and then separated on a C8 column with an isocratic mobile phase containing acetonitrile-water-formic acid mixture (60:40:0.1, v/v/v) at a flow rate of 0.2 mL/min. Each sample had a total run time of 3 min. Quantification was performed using triple quadrupole mass spectrometry in selected reaction monitoring mode with positive electrospray ionization. The method was shown to be highly linear (r2 > 0.99) and to have a wide dynamic range (0.1-100 ng/mL) with favourable accuracy and precision. No matrix effects were observed. The detailed pharmacokinetic profiles of R-phencynonate at therapeutic doses in rats and dogs were characterized by rapid oral absorption, quick clearance, high volume of distribution and poor absolute bioavailability. R-Phencynonate lacked dose proportionality over the oral dose range, based on the power model. However, the area under concentration-time curve and the maximum plasma concentration increased linearly in a dose-dependent manner in both animal models. The absolute bioavailability of R-phencynonate was 16.6 ± 2.75 and 4.78 ± 1.26% in dogs and rats, respectively.


Asunto(s)
Compuestos Aza/sangre , Compuestos Aza/farmacocinética , Cromatografía Liquida/métodos , Glicolatos/sangre , Glicolatos/farmacocinética , Espectrometría de Masas en Tándem/métodos , Administración Oral , Animales , Compuestos Aza/administración & dosificación , Disponibilidad Biológica , Antagonistas Colinérgicos/administración & dosificación , Antagonistas Colinérgicos/sangre , Antagonistas Colinérgicos/farmacocinética , Perros , Glicolatos/administración & dosificación , Masculino , Técnica de Dilución de Radioisótopos , Ratas Sprague-Dawley , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
6.
Phytother Res ; 30(4): 618-26, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26800424

RESUMEN

The herb-derived compounds silymarin, glycyrrhizin, and oxymatrine are widely used to treat chronic hepatitis C virus infections in China. They are often prescribed in combination with ribavirin, which has a narrow therapeutic index. We investigated the influence of these compounds on ribavirin pharmacokinetics following concurrent administration at the human dose in rats. Pharmacokinetic parameters were determined in rats following oral (p.o.) administration of ribavirin (30 mg/kg) with or without silymarin (40 mg/kg, p.o.), glycyrrhizin (15 mg/kg, intraperitoneal [i.p.]), or oxymatrine (60 mg/kg, p.o.). Compared with the animals in ribavirin group, silymarin significantly decreased the area under the plasma concentration-time curve (AUC0-t ) and the peak plasma concentration (Cmax ) of ribavirin and ribavirin base by 31.2-44.5% and 48.9-50.0%, respectively. Glycyrrhizin significantly decreased the Cmax and AUC0-t of both ribavirin and its metabolite by 35.3-37.6% and 38.6-39.8%, respectively. However, silymarin or glycyrrhizin did not change the ribavirin metabolite/parent ratios of the AUC and Cmax . Oxymatrine did not induce significant changes in ribavirin concentration, but it significantly decreased the Cmax (26.6%) and AUC (21.8%) of the metabolite. This study indicates that the therapeutic efficacy of ribavirin may be compromised by the concurrent administration of herbal medicines/dietary supplements containing silymarin, glycyrrhizin, or oxymatrine.


Asunto(s)
Alcaloides/farmacología , Ácido Glicirrínico/farmacología , Quinolizinas/farmacología , Ribavirina/farmacocinética , Silimarina/farmacología , Alcaloides/administración & dosificación , Animales , Área Bajo la Curva , Interacciones Farmacológicas , Ácido Glicirrínico/administración & dosificación , Interacciones de Hierba-Droga , Masculino , Quinolizinas/administración & dosificación , Ratas , Ratas Sprague-Dawley , Ribavirina/administración & dosificación , Silimarina/administración & dosificación
7.
BMC Plant Biol ; 15: 204, 2015 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-26283542

RESUMEN

BACKGROUND: Maize is a major staple food crop globally and contains various concentrations of vitamins. Folates are essential water-soluble B-vitamins that play an important role as one-carbon (C1) donors and acceptors in organisms. To gain an understanding of folate metabolism in maize, we performed an intensive in silico analysis to screen for genes involved in folate metabolism using publicly available databases, followed by examination of the transcript expression patterns and profiling of the folate derivatives in the kernels of two maize inbred lines. RESULTS: A total of 36 candidate genes corresponding to 16 folate metabolism-related enzymes were identified. The maize genome contains all the enzymes required for folate and C1 metabolism, characterized by highly conserved functional domains across all the other species investigated. Phylogenetic analysis revealed that these enzymes in maize are conserved throughout evolution and have a high level of similarity with those in sorghum and millet. The LC-MS analyses of two maize inbred lines demonstrated that 5-methyltetrahydrofolate was the major form of folate derivative in young seeds, while 5-formyltetrahydrofolate in mature seeds. Most of the genes involved in folate and C1 metabolism exhibited similar transcriptional expression patterns between these two maize lines, with the highest transcript abundance detected on day after pollination (DAP) 6 and the decreased transcript abundance on DAP 12 and 18. Compared with the seeds on DAP 30, 5-methyltetrahydrofolate was decreased and 5-formyltetrahydrofolate was increased sharply in the mature dry seeds. CONCLUSIONS: The enzymes involved in folate and C1 metabolism are conserved between maize and other plant species. Folate and C1 metabolism is active in young developing maize seeds at transcriptional levels.


Asunto(s)
Ascomicetos/fisiología , Ácido Fólico/metabolismo , Genoma de Planta , Enfermedades de las Plantas/genética , Transcripción Genética , Zea mays/genética , Zea mays/microbiología , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sitios de Carácter Cuantitativo , Zea mays/metabolismo
8.
J Pharmacol Sci ; 127(4): 414-8, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25953268

RESUMEN

Morroniside is one of the most important iridoid glycosides in the herbal drug Cornus officinalis Sieb. et Zucc. The current study was designed to investigate the ex vivo and in vivo effects of morroniside on CYP3A activity in rats after treatment with morroniside for 7 days (at 10, 30, 90 mg/kg, i.g.). Morroniside was found to induce CYP3A. According to the ex vivo experiment, the activity of CYP3A was measured by the quantification of 1-hydroxymidazolam, which was the metabolite from CYP3A probe substrate, midazolam. The concentration of 1-hydroxymidazolam was determined by using a validated liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) method. The levels of messenger RNA (mRNA) and protein of CYP3A were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting analysis, respectively. The pharmacokinetics of midazolam in rats after treatment with morroniside for 7 days (at 10, 30, 90 mg/kg, i.g.) were investigated in vivo. After treatment with morroniside, the activity, mRNA and protein expression of CYP3A were significantly induced and the absorbance and bioavailability of midazolam in rats were reduced. The results indicated that morroniside could induce the activity of CYP3A.


Asunto(s)
Cornus/química , Citocromo P-450 CYP3A/biosíntesis , Glicósidos/farmacología , Animales , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/fisiología , Inducción Enzimática/efectos de los fármacos , Expresión Génica/efectos de los fármacos , Glicósidos/aislamiento & purificación , Humanos , Masculino , Microsomas Hepáticos/enzimología , Midazolam/farmacocinética , ARN Mensajero/metabolismo , Ratas Sprague-Dawley
9.
Plant Physiol ; 161(2): 971-89, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23129207

RESUMEN

Investigations into the biochemical processes and regulatory mechanisms of nitrogen (N) utilization can aid in understanding how N is used efficiently in plants. This report describes a deficiency in N utilization in an Arabidopsis (Arabidopsis thaliana) transfer DNA insertion mutant of the mitochondrial folylpolyglutamate synthetase gene DFC, which catalyzes the conjugation of glutamate residues to the tetrahydrofolate during folate synthesis. The mutant seedlings displayed several metabolic changes that are typical of plant responses to low-N stress, including increased levels of starch and anthocyanin synthesis as well as decreased levels of soluble protein and free amino acid, as compared with those in wild-type seedlings when external N was sufficient. More striking changes were observed when dfc seedlings were grown under N-limited conditions, including shorter primary roots, fewer lateral roots, higher levels of glycine and carbon-N ratios, and lower N content than those in wild-type seedlings. Gene expression studies in mutant seedlings revealed altered transcript levels of several genes involved in folate biosynthesis and N metabolism. The biochemical and metabolic changes also suggested that N assimilation is drastically perturbed due to a loss of DFC function. The observation that elevated CO(2) partly rescued the dfc phenotypes suggests that the alterations in N metabolism in dfc may be mainly due to a defect in photorespiration. These results indicate that DFC is required for N utilization in Arabidopsis and provide new insight into a potential interaction between folate and N metabolism.


Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas Mitocondriales/metabolismo , Nitrógeno/metabolismo , Péptido Sintasas/metabolismo , Plantones/metabolismo , Aminoácidos/metabolismo , Antocianinas/metabolismo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/genética , Carbono/metabolismo , Ácido Fólico/metabolismo , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Glicina/metabolismo , Immunoblotting , Proteínas Mitocondriales/genética , Mutación , Péptido Sintasas/genética , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Plantones/genética , Plantones/crecimiento & desarrollo , Almidón/metabolismo , Factores de Tiempo
10.
Zhongguo Zhong Yao Za Zhi ; 38(19): 3378-81, 2013 Oct.
Artículo en Zh | MEDLINE | ID: mdl-24422412

RESUMEN

Morroniside, an iridoid glycoside extracted from Cornus officinalis, has multiple pharmacological effects such as neuroprotection. This study took the lead in establishing a method for determining morroniside concentration in rat plasma by high performance liquid chromatography-tandem mass spectrometry. Plasma samples were processed with protein precipitation method, with hyperoside as the internal standard. An Inertsil C8-3 column (2. 1 mm x 50 mm, 5 microm) was adopted, with a mobile phase composed of water (containing 1 mmol L-1 Sodium formate)-acetonitrile (gradient elution) at a flow rate of 0.4 mL . min -1. Electrospray ionization (ESI) was adopted in the positive ion mode for multi-reaction monitoring (MRM). Morroniside showed a good linear relationship ranging between 2-5 000 microg L-1 (r = 0. 995 7), with the minimum limit of quantification of 2 microg L-1. Its precise, accuracy, recovery and matrix effect were all in line with the biological sample measurement requirements. Therefore, the method described above was proved to be suitable for the determination of morroniside concentration in rat plasma. To use the method in the pharmacokinetic study on morroniside in rats, oral administration dose shall be set at 20 mg . kg - to map the plasma concentration-time curve. Main pharmacokinetic parameters were calculated by DAS 2. 0. Specifically, AUC0-inifinity was (587.6 +/- 290. 7) microg min L-1, Cmax was (334.2+/-148.0) microg L-1, Tmax was (0.6 +/-0.3) h, t1/2 was (0.7+/-0.3) h.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Glicósidos/sangre , Espectrometría de Masas en Tándem/métodos , Animales , Masculino , Ratas , Reproducibilidad de los Resultados , Espectrometría de Masa por Ionización de Electrospray
11.
R Soc Open Sci ; 10(8): 230275, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37564064

RESUMEN

In this work, we study systems consisting of a group of moving particles. In such systems, often some important parameters are unknown and have to be estimated from observed data. Such parameter estimation problems can often be solved via a Bayesian inference framework. However, in many practical problems, only data at the aggregate level is available and as a result the likelihood function is not available, which poses a challenge for Bayesian methods. In particular, we consider the situation where the distributions of the particles are observed. We propose a Wasserstein distance (WD)-based sequential Monte Carlo sampler to solve the problem: the WD is used to measure the similarity between the observed and the simulated particle distributions and the sequential Monte Carlo samplers is used to deal with the sequentially available observations. Two real-world examples are provided to demonstrate the performance of the proposed method.

12.
Transl Pediatr ; 12(5): 845-860, 2023 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-37305729

RESUMEN

Background: Despite the availability of various tools of modeling and simulation, clinical pediatric pharmacokinetic (PK) studies remain far less efficient than those on adults due to ethical constraints. One of the optimal solutions is to substitute urine to blood sampling based on explicit mathematic relationships between them. However, this idea is limited by three main knowledge gaps associated with urine data, i.e., complicated excretion equations with excessive parameters, insufficient frequency that is hard to fit, and the mere expression of amounts with no in vivo distribution volume information involved. Methods: To overcome these obstacles, we sacrificed the precision from mechanistic PK models with complex excretion equations to expediency of compartmental model in which a constant ke is used to cover all the internal parameters. And the total cumulative amounts of urinary drug excretion (Xu∞) were estimated and introduced to the excretion equation so that urine data were likely to be fitted using a semi-log-terminal linear regression method. In addition, urinary excretion clearance (CLr) could be calculated by single point plasma data to anchor the plasma concentration-time (C-t) curve based on the assumption that CLr was kept constant throughout the PK process. Results: After sensitivity analysis of two subjective judgements (the selection of the compartmental model and the selection of plasma time point to calculate CLr), the performance of the optimized models was assessed using desloratadine or busulfan as model drugs in a variety of PK scenarios, from i.v. bolus/infusion to p.o. administration, from a single dose to multiple doses, and from rats to children. The fitting plasma drug concentrations of the optimal model were close to the observed value. Meanwhile, the drawbacks inherent to the simplified and idealized modeling strategy were fully identified. Conclusions: The method proposed by this tentative proof-of-principle study was able to deliver acceptable plasma exposure curves and shed light on the future refinements.

13.
Front Pharmacol ; 14: 1119046, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36909160

RESUMEN

Objective: Meldonium, a well-known cardioprotective drug, has been reported to be protective against pulmonary injury at high altitudes; however, the pharmacodynamics of meldonium in other vital organs under acute high-altitude injury are less investigated and the related pharmacokinetics have not been fully elucidated. Methods and Results: The present study examined the basic pharmacodynamics and pharmacokinetics (PK) in rat exposure to acute high-altitude hypoxia after intragastrical and intravenous pre-administration of meldonium. The results indicate that meldonium can improve acute hypoxia-induced pathological damage in brain and lung tissues, and restore blood biochemistry and routine blood index of heart, liver and kidney tissues under a simulated acute high-altitude environment. Furthermore, compared to the normoxia group, rats exposed to simulated high-altitude hypoxia and premedicated with intragastrical meldonium showed linear kinetics in the dose range of 25-100 mg/kg, with a significantly increase in the area under curve (AUC) and reduced clearance rate. No significant differences in these meldonium of PK parameters were observed with intravenous administration. Additionally, meldonium was involved in the regulation of succinic acid and 3-hydroxypropionic acid. Conclusion: These results will contribute to our understanding of the preclinical PK properties of meldonium and its acute high-altitude protective effects.

14.
Front Pharmacol ; 12: 621003, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33935711

RESUMEN

Background: Akebia saponin D (ASD) has a variety of biological activities and great medicinal potential, but its oral bioavailability is so low as to limit its development. Its pharmacokinetic profiles and excretion and metabolism in vivo have not been fully elucidated. This study was an attempt in this area. Methods: A simple LC-MS/MS method to simultaneously quantify ASD and its metabolites M1∼M5 in rat plasma, feces, urine and bile was established with a negative ESI model using dexketoprofen as the internal standard. Meanwhile, the UPLC-HR/MS system was used to screen all possible metabolites in the urine, feces and bile of rats, as compared with blank samples collected before administration. Absolute quantitative analysis was for M0, M3, M4, and M5, while semi-quantitative analysis was for M1, M2, and Orbitrap data. Results: The AUC0-t values after intravenous administration of 10 mg/kg and intragastrical administration of 100 mg/kg ASD were 19.05 ± 8.64 and 0.047 ± 0.030 h*µg/ml respectively. The oral bioavailability was determined to be extremely low (0.025%) in rats. The exposure of M4 and M5 in the oral group was higher than that of M0 in the terminal phase of the plasma concentration time profile, and ASD was stable in the liver microsome incubation system of rats, but metabolism was relatively rapid during anaerobic incubation of intestinal contents of rats, suggesting that the low bioavailability of ASD might have been attributed to the poor gastrointestinal permeability and extensive pre-absorption degradation rather than to the potent first pass metabolism. This assertion was further verified by a series of intervention studies, where improvement of lipid solubility and intestinal permeability as well as inhibition of intestinal flora increased the relative bioavailability to different extents without being changed by P-gp inhibition. After intravenous administration, the cumulative excretion rates of ASD in the urine and bile were 14.79 ± 1.87%, and 21.76 ± 17.61% respectively, but only 0.011% in feces, suggesting that the urine and bile were the main excretion pathways and that there was a large amount of biotransformation in the gastrointestinal tract. Fifteen possible metabolites were observed in the urine, feces and bile. The main metabolites were ASD deglycosylation, demethylation, dehydroxylation, decarbonylation, decarboxylation, hydroxylation, hydroxymethylation, hydroxyethylation and hydrolysis. Conclusion: The pharmacokinetics, bioavailability, metabolism and excretion of ASD in rats were systematically evaluated for the first time in this study. It has been confirmed that the ultra-low oral bioavailability is due to poor gastrointestinal permeability, extensive pre-absorption degradation and biotransformation. ASD after iv administration is not only excreted by the urine and bile, but possibly undergoes complex metabolic elimination.

15.
Acta Pharm ; 69(2): 287-296, 2019 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-31259727

RESUMEN

Morroniside is one of the most important iridoid glycosides from Cornus officinalis Sieb. et Zucc. In the present study, the pharmacokinetics and bioavailability studies of morroniside were conducted on Sprague-Dawley (SD) rats. A rat in situ intestinal perfusion model was used to characterize the absorption of morroniside. Caco-2 cells were used to examine the transport mechanisms of morroniside. The pharmacokinetic study of morroniside exhibited linear dose-proportional pharmacokinetic characteristics and low bioavailability (4.3 %) in SD rats. Its average Peff value for transport across the small intestinal segments changed from (3.09 ± 2.03) × 10-6 to (4.53 ± 0.94) × 10-6 cm s-1. In Caco-2 cells, the Papp values ranged from (1.61 ± 0.53) × 10-9 to (1.19 ± 0.22) × 10-7 cm s-1 for the apical to basolateral side and the Pratio values at three concentrations were all lower than 1.2. Morroniside showed poor absorption and it might not be a specific substrate of P-glycoprotein (P-gp).


Asunto(s)
Cornus/química , Glicósidos/administración & dosificación , Absorción Intestinal , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Animales , Disponibilidad Biológica , Transporte Biológico , Células CACO-2 , Relación Dosis-Respuesta a Droga , Glicósidos/aislamiento & purificación , Glicósidos/farmacocinética , Humanos , Masculino , Ratas , Ratas Sprague-Dawley
16.
Artículo en Inglés | MEDLINE | ID: mdl-18723410

RESUMEN

A sensitive and reproducible high-performance liquid chromatography (HPLC)-UV method for the determination of Z24, a tumorigenesis and angiogenesis inhibitor, has been developed and validated in mouse whole blood. Blood samples were extracted with ether, evaporated, and the residue was reconstituted in mobile phase. An aliquot was separated by isocratic reversed-phase HPLC on a Hypersil ODS-2 column and quantified using UV detection at 390 nm. The mobile phase was 50% (v/v) acetonitrile/water with a flow rate of 0.8 ml/min. A linear curve over the concentration range of 0.05-6 microg/ml (r(2)=0.9976) was obtained. The coefficient of the variation for the intra- and inter-day precision ranged from 3.0 to 10.9% and 5.7 to 10.3%, respectively. The absolute recovery of Z24 was 89.2-108.5%. The method is simple, economical and sufficient for in vivo pharmacokinetic studies on Z24. Nonlinear pharmacokinetics was found in mice at doses from 20 to 80 mg/kg.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Mesilatos/farmacocinética , Pirroles/farmacocinética , Animales , Estabilidad de Medicamentos , Masculino , Mesilatos/sangre , Ratones , Pirroles/sangre , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
17.
Artículo en Inglés | MEDLINE | ID: mdl-17627907

RESUMEN

A sensitive and selective liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of serial chiral novel anticholinergic compounds of phencynonate in rat plasma. After a simple protein-precipitation using methanol, the post-treatment samples were separated on a CAPCELL UG120 column with a mobile phase of a mixture of methanol and water (35:65) containing 0.1% formic acid. The serial chiral analytes and internal standard (IS) were all detected by the use of selected reaction monitoring mode (SRM). The method of all serial chiral analytes developed was validated in rat plasma with a daily working range of 0.5-100 ng/ml with correlation coefficient, R(2) > or = 0.99 and a sensitivity of 0.5 ng/ml as lower limit of quantification, respectively. This method was fully validated for the accuracy, precision and stability studies for all serial chiral analytes. The method proved to be accurate and specific, and was applied to the pharmacokinetic study of serial chiral novel anticholinergic compounds of phencynonate in rat plasma.


Asunto(s)
Compuestos Aza/sangre , Compuestos Aza/química , Antagonistas Colinérgicos/sangre , Antagonistas Colinérgicos/química , Cromatografía Liquida/métodos , Glicolatos/sangre , Glicolatos/química , Espectrometría de Masa por Ionización de Electrospray/métodos , Animales , Compuestos Aza/aislamiento & purificación , Antagonistas Colinérgicos/aislamiento & purificación , Glicolatos/aislamiento & purificación , Isomerismo , Ratas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Espectrometría de Masas en Tándem
18.
J Chromatogr Sci ; 54(6): 912-7, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26896349

RESUMEN

This study was designed to develop a sensitive, simple and rapid method for the quantitation of morroniside in rat urine using high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS) and to investigate the excretion of morroniside in rat urine. The mobile phase consisted of water-acetonitrile (gradient elution) at a flow rate of 0.4 mL/min. Detection was performed using positive-ion electrospray ionization in multiple reaction monitoring (MRM) modes. And the detection of morroniside in rat urine by the LC-MS-MS was accurate and precise from 1.0 to 2,500 ng/mL (a correlation coefficient of 0.9953). The recoveries and matrix effects were all in line with the biological sample measurement requirements. The intraday accuracy was 88.68-105.78% with precision of 6.50-11.19% and the interday accuracy was 95.77-102.43% with precision of 7.08-10.40%. Excretion data of morroniside in rat urine indicated that 21.43‰ (i.g.) and 100.35% (i.v.) of the dose administered was excreted as unconverted form, respectively. And the maximal excretion rate was 27.57 and 482.42 µg/h after oral and intravenous administration, respectively. These results indicated that the developed method has satisfactory sensitivity, accuracy and precision for the quantification of morroniside in rat urine.


Asunto(s)
Glicósidos/farmacocinética , Glicósidos/orina , Urinálisis/métodos , Administración Intravenosa , Administración Oral , Animales , Cromatografía Líquida de Alta Presión , Glicósidos/administración & dosificación , Ratas , Espectrometría de Masas en Tándem
19.
Curr Pharm Biotechnol ; 16(2): 187-93, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25391244

RESUMEN

In this study, sustained-release of GnRH antagonist peptide LXT-101 was realized through oil formulation, and their releasing characteristics in vitro and in vivo were investigated. In this formulation, the static interaction between cationic charged peptide LXT-101 and the negative charged phospholipid led to the formation of the phospholipid-peptide complex, by which LXT-101 was completely dissolved in oils. This formulation was prepared by mixing an aqueous solution of LXT-101 and empty SUV (small unilamellar liposomes) containing EPC (phosphatidylcholine) and DPPG (1, 2-dipalmitog-sn-glycero-3- phosphoglycerol) at an appropriate ratio, the mixture was subsequently lyophilized, and the resultant was dissolved in the oil to form a clear oily solution containing solubilized peptide LXT-101. With atomic force microscopy combined with Langmuir-Blodgett technology, the morphology of the particles in the oily solution were examined to be oval-shaped and the mean particle size was 150 nm in diameter. In pure water at 37°C, about 70~90 % of LXT-101 was released slowly from the oily formulation over 7 days. An effective sustained suppression of testosterone in beagle dogs could be achieved over a period of seven days with this LXT-101 oily formulation, by i.m. at a dose of 0.2 mg/kg (2 mg/ml). This formulation dramatically improved the bioactivity of LXT-101 compared to its aqueous solution. It was also found that when the concentration of peptide LXT-101 was up to or over 10 mg/ml in aqueous solution, there was no significant difference between the oily formulation and aqueous solution. This fact meant that LXT-101 itself could conduct sustained release in vivo by self-assembly of nanofibers.


Asunto(s)
Antagonistas de Hormonas/administración & dosificación , Oligopéptidos/administración & dosificación , Animales , Preparaciones de Acción Retardada/administración & dosificación , Preparaciones de Acción Retardada/química , Preparaciones de Acción Retardada/farmacocinética , Perros , Hormona Liberadora de Gonadotropina/antagonistas & inhibidores , Antagonistas de Hormonas/sangre , Antagonistas de Hormonas/química , Antagonistas de Hormonas/farmacocinética , Inyecciones , Liposomas , Masculino , Ácido Oléico/química , Oligopéptidos/sangre , Oligopéptidos/química , Oligopéptidos/farmacocinética , Fosfatidilcolinas/química , Fosfatidilgliceroles/química , Aceite de Soja/química , Testosterona/sangre , Triglicéridos/química , Agua/química
20.
Mater Sci Eng C Mater Biol Appl ; 56: 348-55, 2015 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-26249600

RESUMEN

Embryonic stem (ES) cells offer the potential to generate all cell types in the body, which provide a promising approach to repair tissue damage or dysfunction. In the past decade, great efforts have been made to induce the differentiation of ES cells into numerous types of cells, such as adipocytes, neurocytes and cardiomyocytes. However, the low differentiated efficiency and successful rate limit the development of induction of the differentiation of stem cells for tissue engineering. Here, we utilize ascorbic acid (AA)-loaded fluorescent TRITC-mesoporous silica nanoparticles (TMSN-AA) as a potential tool to induce the differentiation of human ES cells into cardiomyocytes. The treatment of human ES cells by TMSN-AA nanoplex arrests cell cycle at G1 phase and decreases the expression of stemness genes octamer-binding transcription factor 4 (OCT4) and sex determining region Y-box 2 (SOX2), which exhibits more significant induction efficiency of stem cell differentiation than the treatment by AA alone. Furthermore, we have tested the myocardial marker genes cardiac Troponin I (cTnI) and fetal liver kinase 1 (FLK-1), and found these genes are up-regulated by TMSN-AA nanoplex. Importantly, this work demonstrates the more efficient induction efficiency of human ES cells differentiation by the nanoparticle-drug formulation. Our studies reveal a novel approach based on MSNs as nanocarriers to induce the differentiation of human ES cells into cardiomyocytes efficiently and feasibly, and offer the potential perspectives for tissue engineering, eventually in clinical applications.


Asunto(s)
Ácido Ascórbico/farmacología , Diferenciación Celular/efectos de los fármacos , Sistemas de Liberación de Medicamentos/métodos , Células Madre Embrionarias Humanas/metabolismo , Miocitos Cardíacos/metabolismo , Nanopartículas/química , Dióxido de Silicio , Línea Celular , Células Madre Embrionarias Humanas/citología , Humanos , Miocitos Cardíacos/citología , Porosidad , Dióxido de Silicio/química , Dióxido de Silicio/farmacología
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