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The study of brain diseases has long been of interest to researchers worldwide, and stroke is the third leading cause of death that threatens human health. At the same time, cerebral ischemia–reperfusion injury is closely associated with high rates of disability and mortality. The conditions of the 6‐aminoquinolyl N‐hydroxysccinimidyl carbamate method for the derivatization of amino acids in the bone marrow fluid and hippocampus of C57BL/6 mice with cerebral ischemia–reperfusion injury were explored and optimized, such as the column temperature, concentration of derivatization reagents and mobile phase concentration. The mobile phase consisted of 20 mm sodium acetate solution (phosphoric acid to adjust pH 5.0) and 60% acetonitrile solution at a flow rate of 1 ml min−1. The 23 analytes were separated and determined in a gradient elution procedure; the correlation coefficient r was >0.9990 in the range 0.1–8.0 μg ml−1. The results showed that the content of relevant analytes was significantly changed in the cerebral ischemia–reperfusion injury model, and the method was suitable for the simultaneous determination of 23 amino acids in the bone marrow fluid and hippocampus of C57BL/6 mice. [ABSTRACT FROM AUTHOR]

A simple high performance liquid chromatography (HPLC) method was developed and validated for the determination of coumarin-3-carboxylic acid analogues (C3AA) in rat plasma and a preliminary study on pharmacokinetics. Ferulic acid (FA) was used as the internal standard substance, and coumarin-3-carboxylic acid (C3A) was used as a substitute for quantitative C3AA. After protein precipitation with methanol, the satisfactory separation was achieved on an ODS2 column when the temperature was maintained at 30 ± 2°C. The correlation coefficient r in the C3A linear equation is equal to 0.9990. Pharmacokinetic parameters for t1/2, Tmax, Cmax, area under the curve (AUC)0-t, average residence time (MRT), apparent volume of distribution (V z/F) and clearance (Cl/F) were 1.89 ± 0.03 h, 0.39 ± 0.14 h, 1.81 ± 0.10 g· mL−1 ·h, 7.88 ± 0.24 g·mL−1·h, 3.23 ± 0.14 h, 0.43 ± 0.03 (mg·kg−1)·(g·mL−1)−1·h−1, respectively. The high performance liquid chromatography-photo diode array detector (HPLC-PDA) method established in this study can be used to separate and determine the content of C3AA in plasma of rats after 60% ethanol extraction by gavage. The plasma concentration-time curve and pharmacokinetic parameters reflect the absorption of C3AA in rat blood after oral administration to some extent. [ABSTRACT FROM AUTHOR]

Contrast-enhanced ultrasound (CEUS) is a new form of ultrasound (US) that can dynamically display microvessels in a highly sensitive manner. The purpose of this study was to investigate the efficacy of CEUS for characterizing testicular lesions in comparison with conventional US. Forty-seven patients with testicular lesions were enrolled. The histopathology results revealed that 31 cases were neoplastic (11 cases of seminomas, 8 nonseminomatous germ cell tumors, 8 lymphomas, 2 Leydig cell tumors, and 2 nonspecific tumors), and 16 cases were nonneoplastic (8 cases of infarctions, 3 epidermoid cysts, and 5 inflammation). The indicators of shallow lobulated morphology and cystic-solid echogenicity on conventional US were suggestive of germ cell tumors. More indicators on CEUS were found to be useful for characterizing testicular lesions. All the neoplastic lesions showed hyperenhancement on CEUS. Moreover, germ cell tumors presented with heterogeneous enhancement (73.7%, 14/19), a twisted blood vessel pattern, rapid wash-in and wash-out, and peripheral rim hyperenhancement signs. Lymphoma was characterized by nonbranching linear vessel patterns (87.5%, 7/8), rapid wash-in and slow wash-out. In nonneoplastic lesions, infarction and epidermoid cysts showed no enhancement, and abscesses were observed with marginal irregular enhancement. The sensitivity, specificity, and accuracy of CEUS for differentiating between neoplastic and nonneoplastic lesions were 100%, 93.8%, and 97.9%, respectively, and these values were higher than those for conventional US (90.3%, 62.5%, and 80.9%, respectively). CEUS can sensitively reflect the microvascular perfusion in testicular lesions and offers high accuracy for characterizing them. [ABSTRACT FROM AUTHOR]

Emerging evidence suggests that amino acid (AA) neurotransmitters play important roles in the pathophysiological processes of cerebral ischemia. In this work, an HPLC with fluorescence detection (HPLC‐FLR) method was developed for the simultaneous determination of 18 AAs in the cortex and plasma after cerebral ischemia in mice. The ischemia model was prepared by bilateral common carotid artery occlusion, and then the cortex and plasma of the sham, ischemia, and naringenin groups were collected. Based on the protein precipitation method, a simple and effective sample preparation method was developed. The treated sample contained minimal proteins and lipids. The analysis of the sample was performed by the proposed HPLC‐FLR method in combination with o‐phthalaldehyde. The results showed a statistically significant increase in excitatory AAs (aspartic acid and glutamic acid), inhibitory AAs (glycine and 4‐aminobutyric acid), phenylalanine, citrulline, isoleucine, and leucine levels, and a decrease of glutathione and phenylalanine levels when compared with the sham group in the cortex. Besides, the administration of naringenin had significant effects on excitatory AAs, inhibitory AA (glycine), glutamine, tyrosine, phenylalanine, and leucine levels when compared with the sham group in the cortex. These findings could be utilized in studying and clarifying the mechanisms of ischemia. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatography-electrochemical detection method was developed to determine the concentration of homocysteine and cysteine in the diabetes mellitus Sprague-Dawley male rats' cortex and hippocampus. The cortex and hippocampus of control and diabetes model rats were collected. After pretreatment, the analysis of total homocysteine and cysteine were performed on a C8 column. Under the optimized analytical conditions, the linear correlation coefficients were higher than 0.999 in the concentration range from 0.148 to 22.193 μmol.L−1 with the limit of quantitation of 0.083 μmol.L−1. The extraction recoveries of Hcy and Cys from spiked samples were 90.87–100.25%, and the relative standard deviations (RSD %) were 1.56–9.13%. The established method is simple, accurate, sensitive, and suitable for the separation and determination of Hcy and Cys in biological samples. Compared with the control group, the concentrations of Hcy and Cys in the diabetes group were different in the cortex. The difference suggests that changes in the levels of the two substances may be associated with complications of diabetes mellitus. [ABSTRACT FROM AUTHOR]

Disorders of certain branched‐chain amino acids may be associated with the occurrence and development of non‐alcoholic fatty liver disease. Measurement of related branched‐chain amino acid levels could provide a reference for the clinical and scientific research of the non‐alcoholic fatty liver disease. An established HPLC–FLD method was used to quantify aspartic acid, glutamate, glutamine, glycine, taurine, tyrosine, 4‐amino butanoic acid, tryptophan, methionine, valine, phenylalanine, isoleucine and leucine in mouse brain tissue. Brain tissue samples mixed with internal standard (3‐aminobutyric acid) were processed, then derivatized with 2‐O‐phthaldialdehyde, and finally separated on an ODS2 column through gradient elution at a flow rate of 1.0 ml·min−1. The excitation and emission wavelengths were set at 340 and 455 nm, respectively. The mobile phase A was 100% methanol and the mobile phase B consisted of 30 mmol·L−1 sodium acetate (pH 6.8). The injection volume was 20 μl and the single run time was 45 min. Several parameters, accuracy, precision, and stability, were verified and the results showed the established method had good sensitivity and resolution for all of the 13 compounds and internal standard in mouse brain. [ABSTRACT FROM AUTHOR]

The determination of amino acids with actions like neurotransmitters or modulators has been increasingly important for diagnosis in many neuropsychiatric diseases. A rapid and simple high-performance liquid chromatography with fluorescence detection method was developed for simultaneous determination of seven amino acids: aspartate (Asp), glutamate (Glu), serine (Ser), glutamine (Gln), glycine (Gly), taurine (Tau) and γ-aminobutyric` acid (GABA). Homoserine was used as an internal standard. The analysis was performed on a BDS column with methanol and 50 m m sodium acetate solution (pH 6.5) using a simple gradient elution. Several parameters of the developed method were validated including linearity, accuracy, precision, extraction recovery and stability, which were within the acceptable range. The method was successfully applied to determination of real samples: hippocampus and cortex in depressed rats exposed to chronically unpredictable stress in order to study if there existed differences in the seven amino acids levels between depressed rats and control. The results showed that Asp, Gly, Tau and GABA significantly decreased with increasing Gln in the hippocampus of depressed rats, compared with that of the control group, among which obviously lower level of Asp and higher level of Gln in cortex were observed. The analytical method and the results could be useful for clinical diagnosis and further insight into pathophysiological mechanism of depression. [ABSTRACT FROM AUTHOR]

A high-performance (HPLC) method was established to detect Xeljanz enantiomers in active pharmaceutical ingredients (APIs) and tablets. The separation was achieved on a Chiralpak IC column using a mobile phase of hexane-ethanol-diethylamine (65:35:0.1, v/v). The detection wavelength was 289 nm. The peak areas and the enantiomer concentrations in the range of 0.15-2.25 μg•mL−1 were in high linearity, with correlation coefficients higher than 0.999. The recoveries were 86.44% at the concentrations of 7.5, 18.75, and 37.5 μg•mL−1. The limit of detection (LOD) and limit of quantification (LOQ) were 0.042 and 0.14 μg•mL−1, respectively. This HPLC method is suitable for detecting the enantiomers of Xeljanz in its APIs and tablets. Chirality 27:235-238, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A new fluorescent Al 3+ -sensor ( L ) was designed and synthesized from 8-hydroxyquinoline-7-carbaldehyde (HQ7A) and 4-aminopyrine. The sensor exhibited high selectivity and sensitivity “off-on” fluorescent responses toward Al 3+ in methanol/water (1:9, v/v, acetate buffer, pH 4.5), with about 26-fold enhancement in fluorescence intensity and high sensitivity with the detection limit for Al 3+ as low as 10 −7 M level. The sensor showed a significant fluorescent enhancement for Al 3+ over a wide range of tested metal ions. These suggested that L could be served as a highly selective and sensitive fluorescence sensor for aluminum ion in acid medium, indicating the potential application in acid aqueous environment. [ABSTRACT FROM AUTHOR]

In human plasma, the total concentration of non-protein binding (NPB) drugs is equal to the free drug concentration because NPB drugs do not or hardly bind to plasma proteins. Thus, centrifuge ultrafiltration (CF-UF) has been used in the determination of the concentration of NPB drugs in human plasma. However, with only a common centrifugation, the recovery and the reproducibility were not as excellent as expected. In addition, we discovered that the values of the volume ratio of ultrafiltrate to sample solution (Vu/Vs) were different and could not be well controlled, which may affect the determination of the drug concentration. The problem also affected the determination of other NBP drugs. In the present work, we used biapenem as a representative drug to study the effect of Vu/Vs on the analysis of NPB drugs concentration in human plasma. The results showed that a Vu/Vs value of less than 0.4 had no effect on the analysis of free drug concentration, while a Vu/Vs value of more than 0.4 was associated with increased recovery rate and overestimation of drug concentration. Therefore, to maintain a Vu/Vs value of less than 0.4 and even at a constant value is the key to accurately determine the concentration of NPB drugs in plasma. Fortunately, with an HFCF-UF device, the Vu/Vs could be well controlled and kept at 0.08 in this study. The recovery rates were almost 100% and the analysis precision was greatly improved. In pharmacokinetics studies, this method was successfully employed to determine the concentration of biapenem with excellent accuracy and reproducibility. HFCF-UF may become a feasible platform for the determination of NPB drugs. [ABSTRACT FROM AUTHOR]

A simple sample preparation method has been developed for the determination of amoxicillin in human plasma by hollow fiber centrifugal ultrafiltration (HF–CF–UF). A 400-μL plasma sample was placed directly into the HF–CF–UF device, which consisited of a slim glass tube and a U-shaped hollow fiber. After centrifugation at 1.25 × 103 g for 10 min, the filtrate was withdrawn from the hollow fiber and 20 µL was directly injected into the high-performance liquid chromatography (HPLC) for analysis. The calibration curve was linear over the range of 0.1–20 µg/mL (r = 0.9996) and the limit of detection was as low as 0.025 µg/mL. The average recovery and absolute recovery were 99.9% and 84.5%, respectively. Both the intra-day and inter-day precisions (relative standard deviation) were less than 3.1% for three concentrations (0.25, 2.5 and 10 µg/mL). The sample preparation process was simplified. Only after a single centrifugal ultrafiltration can the filtrate be injected directly into HPLC. The present method is simple, sensitive and accurate. It could be effective for the analysis of biological samples with high protein contents, especially for the biopharmaceutical analysis of drugs that use traditional isolation techniques for sample preparation such as the protein precipitation method. [ABSTRACT FROM AUTHOR]

Abstract: A simple HPLC method was developed to quantify rabbit plasma tetrandrine (Tet) with propranolol (Pro) as internal standard. Based on the established method Tet and Pro were eluted at 7.1 and 12.0min, respectively. It was shown that the concentration-time data of Tet fit the classical two-compartment model, no matter the drug was administered intravenously or orally to rabbits. The values of AUC0→∞, clearance (Cl0→∞), volume of distribution (Vd), and elimination half-life (t1/2β) of Tet were 59861.149±26962.196μg/L⁎min, 0.503±0.173L/min/kg, 179±76.185L/kg, and 283.808±162.937min for intravenous injection of 5mg/kg, or 18986.217±7462.308μg/L⁎min, 0.805±0.267L/min/kg, 110.284±94.176L/kg, and 732.919±847.32min for gavage administration of 10mg/kg , respectively. The results indicate that Tet displays a limited absorption in intestinal tract, even though it has a favorable pharmacokinetic profile after oral or intravenous administration. [Copyright &y& Elsevier]

Abstract: In the paper, a novel fluorescent sensor (1) based on 8-hydroxyquinoline carbaldehyde Schiff-base was synthesized and characterized. This fluorescent sensor exhibited high selectivity for Al3+ over other metal ions with the detection limit reaching below 10−7 M under weak acid aqueous conditions. These suggested that 1 could be served as a highly selective and sensitive fluorescence sensor for aluminum ion in acid medium. [Copyright &y& Elsevier]

The determination of amino acids and monoamine with actions like neurotransmitters or modulators has become increasingly important for studying the relationship between the dysfunction of neurotransmitters and the pathogenesis of diabetic encephalopathy. Here, a high‐performance liquid chromatography with fluorescence detection method was developed to simultaneously determine nine monoamines and amino acids including three excitatory neurotransmitters (aspartate, glutamate, and serotonin), four inhibitory neurotransmitters (glycine, γ‐aminobutyric acid, taurine, dopamine), a precursor of 5‐HT (tryptophan) and methionine using homoserine as the internal standard. The separation was performed on a BDS column with methanol‐buffer solution of 35 mmol/L sodium acetate and 5 mmol/L citric acid (pH 6.0) using a simple gradient elution. Several parameters including specificity, precision, and recovery were validated after optimization of the analytical conditions. The developed method was successfully applied to determine the cortex and the hippocampus samples from Sprague–Dawley rats. Our results showed that various neurotransmitters involved in diabetes mellitus may tend to be differentially modulated and present a different alteration tendency at different time course, which might be associated with the duration of diabetes mellitus. [ABSTRACT FROM AUTHOR]

Inflammation drives the development of depression and may affect neurotransmitters and thus neurocircuits increase the risk of depression. To investigate the influence of inhibition of inflammatory pathways on the biogenic amine neurotransmitters metabolism in depressive rats, sertraline, and meloxicam, the inhibitors of arachidonic acid - cyclooxygenase-2/lipoxygenase (AA-COX-2/5-LO) pathways, were given to depressive rats. After the development of depression model by chronic unpredictable mild stress (CUMS) for 6 weeks, Successful modeling rats were selected and randomly divided into CUMS group and medication administration group. After given medicine, The biogenic amine neurotransmitters in rat cortex and hippocampus were measured by high-performance liquid chromatography equipped with an electrochemical detector (HPLC-ECD). Compared with the normal group, the concentration of norepinephrine (NE) significantly decreased and the concentrations of Tyrosine (Tyr), Tryptophan (Trp), 3,4-dihydroxyphenyl acetic acid (DOPAC), 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) significantly increased in the CUMS group. Sertraline significantly inhibited the elevation of 5-HIAA. Meloxicam inhibited the decrease of NE level in CUMS-induced rat and the increase of Trp, MHPG, and 5-HIAA level in a dose-dependent manner. Caffeic acid inhibited the decrease of NE and the increase of Trp and MHPG in a dose-dependent manner. The inhibition of AA-COX-2/5-LO pathways can improve the behaviors of depression rats and suppress CUMS-induced changes in biogenic amines. Compared with the single-dose lipoxygenase (5-LO) or Cyclooxygenase-2 (COX-2) inhibitor, the combination treatment with meloxicam 1 mg/kg and caffeic acid 10 mg/kg have no significant improvement in CUMS-induced depression behavior and the level of cortical monoamine neurotransmitters and their metabolites.

In recent years, some studies have suggested that the activation of inflammatory system plays a role in the occurrence of depression. Tumor necrosis factor-α (TNF-α), as one of the preinflammatory cytokines, has been reported to be involved in the occurrence of various diseases including depression. Infliximab, an antagonist of TNF-α, is usually used to treat some autoimmune diseases such as Crohn's disease and can perhaps be used to treat other diseases. In this study, the antidepressant effect and a possible mechanism of infliximab were investigated by studying the depression-like behavior and expression of TNF-α, indoleamine 2, 3-dioxygenase (IDO), and 3-hydroxyl amino acid oxygenase (HAAO) from the cortex and hippocampus in rat exposed to chronic unpredicted stress. Forty male Sprague-Dawley rats were divided into a control group (CG), an infliximab-treated control group, a model group (MG), and an infliximab-treated model group (IFXM). Infliximab (5 mg/kg once week) was administered to the infliximab-treated control group and IFXM rats by an intraperitoneal injection, whereas an equivalent volume of vehicle was administered to CG and MG rats. Rat behaviors and the expression of TNF-α, IDO, and HAAO in the cortex and hippocampus were determined. It was found that a significant relief in depression-like behaviors was observed with a downregulation of TNF-α, IDO, and HAAO expression in the IFXM rats compared with MG rats. The results show the antidepressant effect of infliximab and suggest that its mechanism is partly related to inhibition of IDO-HAAO pathway activation mediated by TNF-α in rat brain.

Depression is a common worldwide mental disorder whose etiology remains unclear; there is also a lack of effective therapeutic agents. Sodium valproate (VPA) is a traditional antiepileptic drug with mood-stabilization effect and is increasingly being used to treat bipolar disorders and depression, but its antidepressant mechanism remains unknown. The aim of the present study was to investigate the possible mechanisms of antidepressant action by studying malondialdehyde level, catalase, and superoxide dismutase activities in the serum and the mRNA and protein expression of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) in the prefrontal cortex of rats exposed to chronic unpredicted stress (CUS). Male Sprague-Dawley rats were used to establish a depression model by CUS. VPA (300 mg/kg once daily) and an equivalent volume of vehicle were administered to rats by an intragastric gavage. Rat behaviors, serum malondialdehyde level, serum catalase and superoxide dismutase activities, and the mRNA and protein expressions of TH and TPH in the prefrontal cortex were determined. The results showed that VPA treatment led to a significant decrease in depression-like behaviors, improvement in oxidative stress imbalance, and enhancement of TH, TPH mRNA, and protein expression in stressed rats, but failed to show any significant changes in control rats. This could indicate that the antidepressant mechanism of VPA is perhaps linked to upregulation of TH and TPH expression and inhibition of oxidative damage in CUS rats.

Background: Free drug analysis is increasingly becoming popular in therapeutic drug monitoring (TDM). Centrifugal ultrafiltration (CF-UF) is the primary method to separate free drug from that of bound drug. However, the volume ratio of ultrafiltrate to sample solution (Vu/Vs) affects the accuracy of CF-UF, which highly depends on the different plasma conditions. Plasma protein concentrations in patients are different from those observed in healthy subjects, and there are also significant differences among patients with different diseases. Only very few studies have reported on the effect of protein concentration on the analysis methodology of free drug by CF-UF., Methods: In this study, valproic acid was used as the representative drug, and plasma samples with different albumin concentrations were analyzed by CF-UF and hollow fiber centrifugal ultrafiltration (HFCF-UF)., Results: There was no significant difference of free drug concentrations by HFCF-UF and CF-UF when plasma albumin concentrations ranged 40-60 g/L. However, at low albumin concentrations (<40 g/L), a considerable difference was detected, and the difference was increased with the decrease of plasma albumin concentration. When the albumin concentration was as low as 10 g/L, the free drug concentration was 17.3 mcg/mL by CF-UF, whereas it was 10.2 mcg/mL by HFCF-UF., Conclusions: The accuracy of free drug measurement by CF-UF was albumin concentration dependent. However, such an effect was not observed when samples were prepared by HFCF-UF, which was more suitable for TDM of plasma samples from different patients. Therefore, this method could be readily applied to the measurement of free valproic acid plasma concentrations for TDM in patients.