An in-depth mechanistic study of the p-hydroxyphenylglycine synthetic process using in situ ATR-IR spectroscopy.

In this study, an in situ ATR-IR technique was used as a powerful tool to gain insight into the synthetic process of p-hydroxyphenylglycine (p-HPG) by the sulfamic acid-glyoxylic acid-phenol method. Combined with other chemical and instrumental analysis technologies, the reaction sequence and key intermediates of this one-pot reaction were determined, and two concomitant reaction paths have been put forward for the first time. The possible reaction mechanism has been suggested, and the reaction efficiency of each path is discussed in detail. Through the optimization of the experimental parameters, an approximately 40% increase in the final product yield was achieved compared with previous reports. We believe that this study will without a doubt trigger research interest in understanding the industrial production process of important chemicals and pharmaceuticals and as a result will promote the sustainable development and application of novel, efficient chemical reaction routes.

[Effects of environmental stresses on soil functional stability under different water management measures in a paddy field]. / 环境胁迫对不同水分管理措施下稻田土壤功能稳定性的影响.

With the increase of global environmental changes and intensive anthropogenic activities, it is important to maintain and improve soil function. Here, we evaluated the effects of environmental stress (i.e., drying, high temperature and the combination of drying and high temperature) on soil functional stability (resistance and resilience) under three kinds of water management mea-sures, which included conventional-flooded cultivation, non-flooded with uncovered cultivation and non-flooded with straw mulching. Results showed that, compared to single environmental stress (drying or high temperature), combined stress led to lower soil fungal biomass, bacterial biomass, basal respiration, and soil functional resistance, and higher contents of dissolved organic carbon (DOC) and NH4+-N after one day treatment of stress. Combined stress significantly decreased soil functional resilience after 56 days treatment of stress. Results from the correlation analysis showed that bacterial and fungal biomass were significantly related to soil resistance and resilience. Different water management measures could regulate the effects of environmental stress on soil functional stability. Non-flooded with straw mulching treatment significantly increased the contents of soil DOC, NH4+-N, fungal biomass and bacterial biomass, resulting in higher soil functional resistance and resilience compared with conventional-flooded cultivation and non-flooded with uncovered cultivation under both single and combined stress. In summary, non-flooded with straw mulching could improve soil functional stability under environmental stress, and it could be a suitable agricultural management for non-continuously flooded rice cultivation under multiple stresses.

Prolonged febrile seizures induce inheritable memory deficits in rats through DNA methylation.

AIMS: Febrile seizures (FSs) are the most common types of seizures in young children. However, little is known whether the memory deficits induced by early-life FSs could transmit across generations or not. METHODS: The memory functions of different generations of FS rats were behaviorally evaluated by morris water maze, inhibitory avoidance task, and contextual fear conditioning task. Meanwhile, molecular biology and pharmacological methods were used to investigate the role of DNA methylation in transgenerational transmission of memory defects. RESULTS: Prolonged FSs in infant rats resulted in memory deficits in adult and transgenerationally transmitted to next generation, which was mainly through mothers. For these two generations, DNA methyltransferase (DNMT) 1 was upregulated, leading to transcriptional inhibition of the synaptic plasticity protein reelin but not the memory suppressor protein phosphatase 1. DNMT inhibitors prevented the high expression of DNMT1 and hypermethylation of reelin gene and reversed the transgenerationally memory deficits. In addition, enriched environment in juvenile rats rescued memory deficits induced by prolonged FSs. CONCLUSIONS: Our study demonstrated early experience of prolonged FSs led to memory deficits in adult rats and their unaffected offspring, which involved epigenetic mechanisms, suggesting early environmental experiences had a significant impact on the transgenerational transmission of neurological diseases.

Triphenyltin exposure affects mating behaviors and attractiveness to females during mating in male guppies (Poecilia reticulata).

The impacts of triphenyltin (TPT) on ecological health have been of great concern due to their widespread use and ubiquity in aquatic ecosystems. However, little is known about the effects of TPT on the reproductive behaviors of fishes. Therefore, the present study was conducted to investigate the effects of TPT at environmentally relevant concentrations (0, 1 and 10 ng Sn/L) on the mating behaviors and the attractiveness to females during mating in male guppies (Poecilia reticulata). The results showed that TPT exposure disturbed the mating behaviors; the TPT-exposed male fish performed more sneaking attempts, but no changes in sigmoid courtship were displayed. The increases in sneaking attempts might be related to increases in testosterone levels induced by TPT exposure. In the context of a competing male, the TPT-exposed males were less attractive to females during mating. The decreases in attractiveness might be related to decreases in carotenoid-based coloration, shown as decreases in caudal fin redness values and skin carotenoid contents. In addition, TPT-induced total antioxidant capacities, the activities of superoxide dismutase and catalase, and the contents of malondialdehyde in liver and intestinal tissues indicated increases in oxidative stress. Both oxidative stress and coloration are linked to carotenoids. Thus, we speculated that the TPT-exposed males might use carotenoids to cope with increases in oxidative stress at the expense of carotenoid-based coloration. The disruption of mating behaviors and the decrease in attractiveness to females in male fish could result in reproductive failure. The present study underscores the importance of using behavioral tests as a sensitive tool in assessing the impact of pollutants present in aquatic environments.

Study on the metabolites of betulinic acid in vivo and in vitro by ultra high performance liquid chromatography with time-of-flight mass spectrometry.

Betulinic acid is a triterpenoid organic acid with remarkable antitumor properties and is naturally present in many fruits, condiments and traditional Chinese medicines. Currently, a strategy was developed for the identification of metabolites following the in vivo and in vitro biotransformation of Betulinic acid with rat intestinal bacteria utilizing ultra high performance liquid chromatography with time-of-flight mass spectrometry with polymeric solid-phase extraction. As a result, 46 metabolites were structurally characterized. The results demonstrated that Betulinic acid is universally metabolized in vivo and in vitro, and Betulinic acid could undergo general metabolic reactions, including oxidation, methylation, desaturation, loss of O and loss of CH2 . Additionally, the main metabolic pathways in vivo and in vitro were determined by calculating the relative content of each metabolite. This is the first study of Betulinic acid metabolism in vivo, whose results provide novel and useful data for better understanding of the safety and efficacy of Betulinic acid.

Reconfigurable logic in nanosecond Cu/GeTe/TiN filamentary memristors for energy-efficient in-memory computing.

Owing to the capability of integrating the information storage and computing in the same physical location, in-memory computing with memristors has become a research hotspot as a promising route for non von Neumann architecture. However, it is still a challenge to develop high performance devices as well as optimized logic methodologies to realize energy-efficient computing. Herein, filamentary Cu/GeTe/TiN memristor is reported to show satisfactory properties with nanosecond switching speed (<60 ns), low voltage operation (<2 V), high endurance (>104 cycles) and good retention (>104 s @85 °C). It is revealed that the charge carrier conduction mechanisms in high resistance and low resistance states are Schottky emission and hopping transport between the adjacent Cu clusters, respectively, based on the analysis of current-voltage behaviors and resistance-temperature characteristics. An intuitive picture is given to describe the dynamic processes of resistive switching. Moreover, based on the basic material implication (IMP) logic circuit, we proposed a reconfigurable logic method and experimentally implemented IMP, NOT, OR, and COPY logic functions. Design of a one-bit full adder with reduction in computational sequences and its validation in simulation further demonstrate the potential practical application. The results provide important progress towards understanding of resistive switching mechanism and realization of energy-efficient in-memory computing architecture.

UPLC-Q-TOF-MS/MS-guided dereplication of Pulsatilla chinensis to identify triterpenoid saponins.

INTRODUCTION: Triterpenoid saponins are the major bioactive constituents of Pulsatilla chinensis, playing an important role in various biological activities such as anti-tumour, cognition-enhancing, anti-biosis, anti-inflammatory, hypoglycemic and immunological adjuvant. OBJECTIVE: To establish a systematic strategy based on ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) for the efficient characterisation and identification of triterpenoid saponins in crude extracts from Pulsatilla chinensis. METHODOLOGY: In this work, the strategy includes two aspects: (1) positive mode: by target screening, we can deduce the aglycone type and the composition of sugar moiety according to the fragment ions; untargeted screening includes four steps, find unknown, formula finder, ChemSpider search and MS/MS identification; (2) negative mode: according to the MS/MS spectra, the composition of sugar chain bonded to C-28 is inferred reasonably. The extract of Pulsatilla chinensis was separated within 60 min on a C18 column and eluted with methanol and water both containing 0.1% formic acid. RESULTS: As a result, a total of 22 triterpenoid saponins (11 pairs of isomers) with four aglycone skeletons were tentatively identified or elucidated in crude extracts from Pulsatilla chinensis based on their retention times, the mass spectrometric fragmentation patterns, and MS and MS/MS data. CONCLUSION: This study provides an efficient analysis strategy to rapidly identify the triterpenoid saponins in Pulsatilla species even in traditional Chinese medicines.

Discrimination and Chemical Phylogenetic Study of Four Pulsatilla Herbs Using UPLC-ESI-MS/MS Combined with Hierarchical Cluster Analysis.

A tissue-smashing based ultra-rapid extraction coupled with ultra-performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS) method was developed to determine 10 major triterpenoid saponins from Pulsatilla herbs. Compound 4 was characterized as betulinic acid glycoside 3-O-α-arabinopyranosyl-28-O-ß-glucopyranosyl-23-hydroxy with HR-ESI-MS, 1H-NMR and 13C-NMR experiment. The MS spectra result showed that the ionization of compound 4 was more efficient in the positive mode. Meanwhile, the ions at m/z 789.6 and m/z 627.5 were selected as precursor and product ion for the determination, respectively. The chromatographic separation was carried out on a Phenomenex Kinetex C18 column using a gradient mobile phase system composed of 0.1% formic acid both in methanol and water at a flow rate of 0.4 mL/min. The detection was performed by multiple reaction monitoring mode, using electrospray ionization in the positive and negative mode. The total run time was 6 min. The calibration curves possessed good linearity with all coefficients higher than 0.9987. The intra- and interday precisions were no more than 4.9%, and the average recoveries were from 97.6% to 103.4% with RSD <4.7%. Moreover, hierarchical cluster analysis was performed to compare and discriminate the Pulsatilla herbs based on the quantitative data. The hierarchical cluster analysis results demonstrated that Pulsatilla chinensis, Pulsatilla cernua, Pulsatilla dahurica, Pulsatilla turczainovii samples could be easily discriminated from each other based on the contents of triterpenoid saponins and the established method is feasible for quality control of Pulsatilla herbs.

Serum resistin positively correlates with serum lipids, but not with insulin resistance, in first-degree relatives of type-2 diabetes patients: an observational study in China.

To investigate whether serum resistin correlated with hypertension, obesity, dyslipidemia, or insulin resistance (IR) in Chinese type 2 diabetes mellitus (T2DM) patients and their first-degree relatives (DFDRs) in a case-control observational study.We determined the serum levels of resistin, plasma lipids, glucose, and insulin, and performed clinical assessments of hypertension, obesity, and IR for 42 T2DM patients, 74 of their DFDRs, and 51 healthy control participants with no family history of T2DM (NC group). The biochemical and clinical variables were compared between the 3 groups, and relationships between serum resistin and the other variables were evaluated using a Pearson correlation analysis.Significant trends were observed in the triglyceride, HbA1c, and resistin levels, in which the values observed in the DFDR group were intermediate to those of the T2DM and NC groups (P < .05 for all). A stratified analysis revealed significant trends in the resistin level and scores for homeostasis model assessment (HOMA) indexes for IR and insulin sensitivity in women and in the HbA1c and resistin levels in men (P < .05 for all), with DFDR subjects exhibiting intermediate values. The Pearson analysis showed that serum resistin positively correlated with total cholesterol and low-density lipoprotein cholesterol in the DFDR group only (P < .05 for both), and that resistin did not correlate significantly with HOMA indexes, blood glucose, insulin, HbA1c, triglyceride, high-density lipoprotein cholesterol, BMI, waist or hip circumference, or blood pressure.Our results suggest that elevated serum resistin might contribute to an increased risk of hyperlipidemia in DFDRs of Chinese T2DM patients.

Simultaneous determination of 12 active components in the roots of Pulsatilla chinensis using tissue-smashing extraction with liquid chromatography and mass spectrometry.

Ultra high performance liquid chromatography coupled with mass spectrometry and combining a tissue-smashing extraction technique was developed for the simultaneous quantitative analysis of 12 compounds in the roots of Pulsatilla chinensis. Among them, compound 6 was characterized and accurately quantified in this herb for the first time. The parameters of extraction condition were simultaneously optimized with a Box-Behnken design and Derringer's function. The optimized conditions were as follows: sample quantity of 0.5 g, ethanol concentration of 70%, and extraction time of 200 s. Multiple-reaction monitoring scanning was employed for the quantification between positive and negative mode in a single run of 6 min. Full validation of the method was carried out, and the results indicated that the method was rapid, specific, and reliable. The developed method was successfully applied to quantify the 12 compounds in 33 batches of P. chinensis from different provinces. Moreover, the principal component analysis was performed to compare the P. chinensis collected from different provinces of China based on quantitative data and the results indicated that the content of compounds could be used to differentiate the origins of P. chinensis. These results demonstrated that this method is feasible and reliable for the quality control of P. chinensis.

Histamine up-regulates astrocytic glutamate transporter 1 and protects neurons against ischemic injury.

Astrocytic glutamate transporter 1 (GLT-1) is responsible for the majority of extracellular glutamate clearance and is essential for preventing excitotoxicity in the brain. Up-regulation of GLT-1 shows benefit effect on ischemia-induced neuronal damage. In present study, we examined the effect of histamine, a neurotransmitter or neuromodulator, on GLT-1 expression and function. In acute hippocampal slices, histamine selectively increased GLT-1 expression independent of neuronal activities. Similar up-regulation of GLT-1 was also observed after histamine treatment in pure cultured astrocytes, which was abolished by H1 receptor antagonist or PKC inhibitor. Cell surface biotinylation and whole-cell patch recordings of glutamate transporter current confirmed the up-regulation of functional GLT-1 following histamine exposure. Histamine treatment decreased the extracellular glutamate content and alleviated neuronal cell death induced by exogenous glutamate challenge. Moreover, we found a significant neuroprotective effect of histamine in brain slices after oxygen-glucose deprivation (OGD). In addition, histidine, the precursor of histamine, also showed neuroprotection against ischemic injury, which was accompanied by reversion of declined expression of GLT-1 in adult rats subjected to middle cerebral artery occlusion (MCAO). These neuroprotective effects of histamine/histidine were blocked by GLT-1 specific inhibitor dihydrokainate or H1 receptor antagonist. In summary, our results suggest that histamine up-regulates GLT-1 expression and function via astrocytic H1 receptors, thus resulting in neuroprotection against excitotoxicity and ischemic injury.

Wide therapeutic time-window of low-frequency stimulation at the subiculum for temporal lobe epilepsy treatment in rats.

Low-frequency stimulation (LFS) has been considered as an option for the treatment of intractable epilepsy. However, previous data showed that LFS of certain brain regions only exerts its effect within a very narrow therapeutic time window, which lasts from seconds to tens of seconds, thus restricting its clinical application. The present study was designed to determine whether there exists a target with a wider therapeutic window for LFS treatment. Therefore, evoked seizures in the rat were induced by amygdala kindling and spontaneous seizures were induced by pilocarpine. The effects of different modes of LFS at the subiculum on the progression and severity of evoked seizures and the frequency of spontaneous seizure were evaluated. We found that (i) LFS at 1Hz delivered to the subiculum before and immediately after the kindling stimulations, or after the cessation of afterdischarge (afterdischarge duration, ADD) decreased the seizure stages and shortened the ADD both in seizure acquisition and expression in amygdaloid-kindled seizures. In addition, even LFS delivered after duration of double the ADD prolonged the kindling progression. (ii) LFS delivered at 1Hz, but not 0.5, 3 or 130Hz, immediately after the cessation of kindling stimulations retarded the progression of kindling seizures. (iii) Pilocarpine-induced spontaneous seizures were completely inhibited by 1Hz LFS. Thus, these results demonstrated that LFS of the subiculum has a wide therapeutic time-window for temporal lobe epilepsy treatment in rats, suggesting that the subiculum may be a promising and suitable target for clinical application.

Role of gap junctions in epilepsy.

Epilepsy is a common neurological disorder characterized by periodic and unpredictable seizures. Gap junctions have recently been proposed to be involved in the generation, synchronization and maintenance of seizure events. The present review mainly summarizes recent reports concerning the contribution of gap junctions to the pathophysiology of epilepsy, together with the regulation of connexin after clinical and experimental seizure activity. The anticonvulsant effects of gap junction blockers both in vitro and in vivo suggest that the gap junction is a candidate target for the development of antiepileptic drugs. It is also of interest that the roles of neuronal and astrocytic gap junctions in epilepsy have been investigated independently, based on evidence from pharmacological manipulations and connexin-knockout mice. Further studies using more specific manipulations of gap junctions in different cell types and in human epileptic tissue are needed to fully uncover the role of gap junctions in epilepsy.