Practice-Oriented Retest Learning as the Basic Form of Cognitive Plasticity of the Aging Brain

It has been well documented that aging is associated with declines in a variety of cognitive functions. A growing body of research shows that the age-related cognitive declines are reversible through cognitive training programs, suggesting maintained cognitive plasticity of the aging brain. Retest learning represents a basic form of cognitive plasticity. It has been consistently demonstrated for adults in young-old and old-old ages. Accumulated research indicates that retest learning is effective, robust, endurable and could occur at a more conceptual level beyond item-specific memorization. Recent studies also demonstrate promisingly broader transfer effects from retest practice of activities involving complex executive functioning to other untrained tasks. The results shed light on the development of self-guided mental exercise programs to improve cognitive performance and efficiency of the aging brain. The relevant studies were reviewed, and the findings were discussed in light of their limitations, implications, and future directions

Visualization and characterization of gas-liquid mass transfer around a taylor bubble right after the formation stage in microreactors

The gas-liquid mass transfer occurring in Taylor flows right after the bubble formation stage were investigated in a flow-focusing microreactor. The colorimetric technique proposed by Dietrich et al.(2013) was used for locally visualizing and characterizing the gas-liquid mass transfer. Thanks to this method, the liquid-side mass transfer coefficients kL were measured at the moment right after the bubble is detaching from the gas film near the cross-junction of the microreactor. Experiments were carried out for several flow conditions (95.7<Re<226.1,0.0043<Ca<0.010,0.4<We<2.3,Bo=0.044)and bubble size (2.34 < Lb/l < 5.59). The results have demonstrated that the contribution of mass transfer right after the bubble formation stage is reasonably larger to those obtained at the bubble flowing-stag

Optical methods to investigate the enhancement factor of an oxygen-sensitive colorimetric reaction using microreactors

Visualization of mass transfer is a powerful tool to improve understanding of local phenomenon. The use of an oxygen-sensitive dye (colorimetric technique1) has showed its relevancy for locally visualizing and characterizing gas-liquid mass transfer at different scales2,3. At present, the occurrence of a possible enhancement of the gas-liquid mass transfer by this reaction has not been yet demonstrated. This paper aims at filling this gap by evaluating the Hatta number Ha and the enhancement factor E associated with the oxygen colorimetric reaction when implementing in milli/micro channels. For that, as data on the kinetic of the colorimetric reaction are seldom in the literature, the reaction characteristic time was firstly estimated by carrying out experiments in a microchannel equipped with a micromixer. The diffusion coefficients of dihydroresorufin and O2 were then determined by implementing two original optical methods in a specific coflow microchannel device, coupled with theoretical modelling. The knowledge of these parameters enabled at last to demonstrate that no enhancement of the gas-liquid mass transfer by this colorimetric reaction existed. Complementary information about the reliability of the colorimetric technique to characterize the gas-liquid mass transfer in milli/micro systems was also give

Farrerol ameliorates diabetic hepatopathy in rat model of type 2 diabetes mellitus via modulation of oxidativeinflammatory stress

Purpose: To investigate the effect of farrerol on diabetic hepatopathy in a rat model of type 2 diabetes mellitus (T2DM).Methods: Adult male Wistar rats (n = 40) were randomly assigned to four groups of ten rats each: normal control, diabetic control, farrerol control and treatment groups. With the exception of normal control and farrerol control groups, the rats were fed high-fat diet (HFD) for four weeks, and thereafter injected streptozotocin (STZ) at a dose of 30 mg/kg body weight intraperitoneally (i.p.) for induction of T2DM. Rats in farrerol control and treatment groups received 50 mg/kg farrerol orally/day. Serum levels of triacylglycerol (TG), total cholesterol (TC), high-density lipoprotein&nbsp; cholesterol (HDL-C) and lowdensity lipoprotein cholesterol (LDL-C) were determined. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were assessed in liver homogenate while mRNA and protein expressions of glucose transporter 2 (GLUT2) were assayed in liver using real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting, respectively. Expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also determined using qRT-PCR.Results: Diabetes mellitus (DM) led to significant reductions in rat body weight and SOD activity, while increasing fasting blood glucose (FBG) and MDA levels (p &lt; 0.05). However, treatment with farrerol significantly reversed the effect of DM on these parameters (p &lt; 0.05). The mRNA expressions of TNF-α and IL-1β were significantly higher in diabetic control group than in normal control group, but were significantly reduced after farrerol treatment (p &lt; 0.05). Treatment with farrerol also significantly reversed the effect of DM on rat lipid profile (p &lt; 0.05). The expression of GLUT2 protein was significantly downregulated in the liver of diabetic control rats, when compared with normal control rats, but was significantly upregulated after treatment with farrerol (p &lt; 0.05).Conclusion: The results of this study show that farrerol alleviates STZ-induced hyperglycemia and dyslipidemia via reduction in oxidative stress and inflammation, and upregulation of GLUT2 protein expression. Thus, farrerol has antidiabetic and hepatoprotective potentials for clinical use in&nbsp; humans. Keywords: Diabetes mellitus, Dyslipidemia, Farrerol, Hepatopathy, High-fat die

Metoprolol, N-Acetylcysteine, and Escitalopram Prevents Chronic Unpredictable Mild Stress-Induced Depression by Inhibition of Endoplasmic Reticulum Stress

Background: Endoplasmic reticulum stress (ERS) has been recently suggested to be activated in the major depressive disorder (MDD). However, whether ERS is a potential therapeutic target for MDD is largely unknown. Here we attempted to assess the preventive effect of metoprolol (MET), N-acetylcysteine (NAC), and escitalopram (ESC) on chronic unpredictable mild stress (CUMS)-induced depression and investigate whether ERS mediates the antidepressant role of these drugs.Method: Forty-five sprague-dawley rats were randomly divided into five groups: control, CUMS, CUMS+ESC, CUMS+NAC, and CUMS+MET. Weight measurement, open field activity and sucrose preference were performed before and after stress. Hippocampal nerve cells and capillary ultrastructure were observed by transmission electron microscope, and hippocampal cells apoptosis were detected by flow cytometry. Furthermore, expression of ERS markers glucose-regulated protein 78 (GRP78), C/EBP-homologous protein (CHOP), and caspase-12 were measured by western blot and qRT-PCR.Results: The CUMS-induced rats showed significantly increased depressive-like behaviors including decreased open field activity and sucrose preference. Moreover, CUMS-exposed rats exhibited significantly increased hippocampal cell apoptosis, and showed damage in hippocampal nerve cells and capillary ultrastructure. Furthermore, ESC and NAC not only mitigated depressive-like behaviors, but also decreased apoptosis and pathologies, while MET fail to decrease apoptosis. Moreover, CUMS stimulation significantly elevated ERS by increasing the levels of GRP78, CHOP, and decreasing the level of caspase-12, while ESC, NAC, and MET significantly decreased the ERS.Conclusion: ESC, NAC, and MET might prevent the MDD partly through inactivating the ERS. These findings demonstrated ERS as a novel treatment target for depression

Metabolic engineering of the L-phenylalanine pathway in Escherichia coli for the production of S- or R-mandelic acid

<p>Abstract</p> <p>Background</p> <p>Mandelic acid (MA), an important component in pharmaceutical syntheses, is currently produced exclusively via petrochemical processes. Growing concerns over the environment and fossil energy costs have inspired a quest to develop alternative routes to MA using renewable resources. Herein we report the first direct route to optically pure MA from glucose via genetic modification of the L-phenylalanine pathway in <it>E. coli</it>.</p> <p>Results</p> <p>The introduction of hydroxymandelate synthase (HmaS) from <it>Amycolatopsis orientalis </it>into <it>E. coli </it>led to a yield of 0.092 g/L S-MA. By combined deletion of competing pathways, further optimization of S-MA production was achieved, and the yield reached 0.74 g/L within 24 h. To produce R-MA, hydroxymandelate oxidase (Hmo) from <it>Streptomyces coelicolor </it>and D-mandelate dehydrogenase (DMD) from <it>Rhodotorula graminis </it>were co-expressed in an S-MA-producing strain, and the resulting strain was capable of producing 0.68 g/L R-MA. Finally, phenylpyruvate feeding experiments suggest that HmaS is a potential bottleneck to further improvement in yields.</p> <p>Conclusions</p> <p>We have constructed <it>E. coli </it>strains that successfully accomplished the production of S- and R-MA directly from glucose. Our work provides the first example of the completely fermentative production of S- and R-MA from renewable feedstock.</p