Sonochemical synthesis of Ag nanoclusters: electrogenerated chemiluminescence determination of dopamine

We report a facile one‐pot sonochemical approach to preparing highly water‐soluble Ag nanoclusters (NCs) using bovine serum albumin as a stabilizing agent and reducing agent in aqueous solution. Intensive electrogenerated chemiluminescence (ECL) was observed from the as‐prepared Ag (NCs) and successfully applied for the ECL detection of dopamine with high sensitivity and a wide detection range. A possible ECL mechanism is proposed for the preparation of Ag NCs. With this method, the dopamine concentration was determined in the range of 8.3 × 10^–9 to 8.3 × 10^–7 mol/L without the obvious interference of uric acid, ascorbic acid and some other neurotransmitters, such as serotonin, epinephrine and norepinephrine, and the detection limit was 9.2 × 10^–10 mol/L at a signal/noise ratio of 3. Copyright © 2013 John Wiley & Sons, Ltd.     

Activated Cyclin-Dependent Kinase 5 Promotes Microglial Phagocytosis of Fibrillar β-Amyloid by Up-regulating Lipoprotein Lipase Expression

Amyloid plaques are crucial for the pathogenesis of Alzheimer disease (AD). Phagocytosis of fibrillar β-amyloid (Aβ) by activated microglia is essential for Aβ clearance in Alzheimer disease. However, the mechanism underlying Aβ clearance in the microglia remains unclear. In this study, we performed stable isotope labeling of amino acids in cultured cells for quantitative proteomics analysis to determine the changes in protein expression in BV2 microglia treated with or without Aβ. Among 2742 proteins identified, six were significantly up-regulated and seven were down-regulated by Aβ treatment. Bioinformatic analysis revealed strong over-representation of membrane proteins, including lipoprotein lipase (LPL), among proteins regulated by the Aβ stimulus. We verified that LPL expression increased at both mRNA and protein levels in response to Aβ treatment in BV2 microglia and primary microglial cells. Silencing of LPL reduced microglial phagocytosis of Aβ, but did not affect degradation of internalized Aβ. Importantly, we found that enhanced cyclin-dependent kinase 5 (CDK5) activity by increasing p35-to-p25 conversion contributed to LPL up-regulation and promoted Aβ phagocytosis in microglia, whereas inhibition of CDK5 reduced LPL expression and Aβ internalization. Furthermore, Aβ plaques was increased with reducing p25 and LPL level in APP/PS1 mouse brains, suggesting that CDK5/p25 signaling plays a crucial role in microglial phagocytosis of Aβ. In summary, our findings reveal a potential role of the CDK5/p25-LPL signaling pathway in Aβ phagocytosis by microglia and provide a new insight into the molecular pathogenesis of Alzheimer disease.Alzheimer disease (AD)¹ is one of the most common neurodegenerative disorders, which is characterized by pathological hallmarks such as neuronal and synaptic loss, neurofibrillary tangles (NFTs), and senile plaques. The intracellular NFTs are mainly composed of hyper-phosphorylated microtubule-associated protein tau, whereas toxic fibrillar β-amyloid (fAβ) as the main component of senile plaques is generated by sequential proteolytic cleavage of trans-membrane β-amyloid precursor protein (APP) by β- and γ-secretases. fAβ can induce oxidative stress-mediated neuronal cell death and cause cognitive impairment in mouse brains (1). Many reports suggest that fAβ induces dysregulation of two pivotal kinases CDK5 (2, 3) and GSK-3 (4), which are crucial regulators of hyperphosphorylated tau and increased production of Aβ from APP, and thereby triggers the cascade of signal transduction events underlying neuronal cell death in AD pathogenesis.As the resident immune cells in the brain, microglia can be activated in response to fAβ and often accumulate around the amyloid deposits in the brains of AD patients. Activated microglia trigger the production of inflammatory factors, reactive oxygen species, and chemokines, which may cause neuronal cell death (5). Furthermore, increasing evidence supports that activated microglia exert a vital beneficial role in the clearance of Aβ by phagocytosis. Many receptors, including scavenger receptor A (SR-A) (6), scavenger receptor class B type I (SR-BI) (7), lipopolysaccharide receptor (CD14) (8), CD33 (9), B-class scavenger receptor CD36 (10), CD47 (11), β1 integrin (12), toll-like receptor 2 (TLR2) (13), and toll-like receptor 4 (TLR4) (14), have been implicated in microglial phagocytosis of fAβ via direct or indirect binding to Aβ. Microglial phagocytosis of fAβ is also regulated by proinflammatory cytokines (15) and chemokine receptor CX3CR1 (16). Farfara et al. reported that the γ-secretase component presenilin, which is responsible for APP cleavage and Aβ production in neurons, is important for microglial fAβ clearance, indicating a dual role for presenilin in neuronal cell death and microglial phagocytosis (17). In addition, accumulating evidence suggests a critical role of lipids and lipoproteins in microglial fAβ phagocytosis and clearance. Lee et al. reported that apolipoprotein E (ApoE) enhances fAβ trafficking and degradation, indicating a role of cholesterol in fAβ degradation (18). After internalization, fAβ is degraded through the lysosome pathway (19, 20). However, the mechanism underlying microglial internalization of fAβ remains unclear.Stable isotope labeling of amino acids in cell culture (SILAC) is an accurate and reproducible mass spectrometry-based quantitative proteomics approach for examining changes in protein expression or post-translational modifications at a large scale (21, 22). Here, we used the SILAC quantitative proteomics strategy to investigate changes in the protein levels in BV2 microglia treated with fAβ. We found that 6 proteins were up-regulated and 7 were down-regulated significantly by Aβ treatment. Interestingly, bioinformatic analysis revealed that most of these up- or down-regulated proteins, including lipoprotein lipase (LPL), were mainly distributed in the cell membrane. We verified that LPL was up-regulated at both gene and protein levels in BV2 and primary microglia in response to fAβ, thereby indicating its role in the microglial phagocytosis of Aβ. Importantly, we further demonstrated that CDK5, which is a critical serine/threonine kinase in the pathogenesis of AD, regulated the expression of LPL and played a critical role in Aβ phagocytosis of microglia. Moreover, we found that increase in the p35-to-p25 conversion contributed to the enhanced CDK5 activity under Aβ stimulus and played a vital role in regulation of LPL expression and microglial Aβ phagocytosis. Our results suggest a role of the CDK5/p25-LPL signaling pathway in Aβ phagocytosis of microglia and provide valuable information to understand the molecular mechanism underlying microglial fAβ phagocytosis.     

Inhibition of hydrogen sulfide synthesis provides protection for severe acute pancreatitis rats via apoptosis pathway

We aimed to investigate the relationship between the synthesis of hydrogen sulfide (H₂S) and the pancreatic acinar cell apoptosis in severe acute pancreatitis (SAP) rats, as well as analyse the potential apoptotic pathway involved in this process. Sixty rats had been equally divided into four groups: sham, SAP, SAP + sodium hydrosulfide (NaHS) and SAP + DL-propargylglycine (PAG). 24 h after SAP induction, all surviving animals of each group were sacrificed to collect blood and tissue samples for the following measurements: the level of serum H₂S as well as the levels of tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), H₂S synthesizing activity, CSE mRNA and protein expression, maleic dialdehyde (MDA) and myeloperoxidase (MPO) activity, the expression of Bax, Bcl-2, caspase-3, -8 and -9, the release of cytochrome c and the activation of nuclear factor-kappa B (NF-κB), ERK1/2, JNK1/2 and p38 in pancreas. Furthermore, in situ detection of cell apoptosis was examined and the severity of pancreatic damage was analyzed by pathological grading and scoring. Results Significant differences in every index except IL-10 had been found between the SAP, NaHS and PAG groups (P < 0.05). Treatment with PAG obviously induced the pancreatic acinar cell apoptosis as well as improved all the pathological changes and inflammatory parameters. In contrast, administration of NaHS significantly attenuated apoptosis in the pancreas and aggravated the severity of pancreatic damage. Moreover, the expressions of caspase-3, -8, -9 and the release of cytochrome c were all increased in the apoptotic cells, and the activity of NF-κB as well as the phosphorylation of ERK1/2, JNK1/2 and p38 decreased accompanying with the reduction of the serum H₂S level. H₂S plays a pivotal role in the regulation of pancreatic acinar cell apoptosis in SAP rats. The present results showed that inhibition of H₂S synthesis provided protection for SAP rats via inducing acinar cell apoptosis. This process acted through both extrinsic and intrinsic apoptotic pathways, and may be regulated by reducing the activity of NF-κB.     

Development of InDel markers linked to Fusarium wilt resistance in cabbage

Cabbage Fusarium wilt (CFW) is a destructive disease causing great losses to cabbage (Brassica oleracea L. var. capitata L.) production worldwide. At present, there are few reports concerning molecular marker research on cabbage resistance to CFW. In this study, 160 double haploid (DH) lines were obtained from the F1 population of a 99–77 (highly resistant to CFW) × 99–91 (highly susceptible to CFW) cross. Insertion–deletion (InDel) markers were designed according to the reference genome sequence of cabbage and the whole-genome re-sequencing data of the two parents. A genetic map of chromosome C06 including seven InDel markers was constructed based on the DH population. Thus, FOC (resistance gene to Fusarium oxysporum f. sp. conglutinans) was located on chromosome C06 and two InDel markers out of the seven, M10 and A1, flanked the gene at 1.2 and 0.6 cM, respectively. Marker A1 revealed a significant consistency with the phenotype assay in the F2 population as well as in 40 inbred lines (96 and 82 %, respectively). This study lays the foundation for fine mapping and cloning of the FOC gene and for marker-assisted selection in cabbage resistance breeding.     

Isolation and Quantification of MicroRNAs from Urinary Exosomes/Microvesicles for Biomarker Discovery

Recent studies indicate that microRNA (miRNA) is contained within exosome. Here we sought to optimize the methodologies for the isolation and quantification of urinary exosomal microRNA as a prelude to biomarker discovery studies. Exosomes were isolated through ultracentrifugation and characterized by immunoelectron microscopy. To determine the RNA was confined inside exosomes, the pellet was treated with RNase before RNA isolation. The minimum urine volume, storage conditions for exosomes and exosomal miRNA was evaluated. The presence of miRNAs in patients with various kidney diseases was validated with real-time PCR. The result shows that miRNAs extracted from the exosomal fraction were resistant to RNase digestion and with high quality confirmed by agarose electrophoresis. 16ml of urine was sufficient for miRNA isolation by absolute quantification with 4.15×10⁵ copies/ul for miR-200c. Exosomes was stable at 4℃ 24h for shipping before stored at -80℃ and was stable in urine when stored at -80°C for 12months. Exosomal miRNA was detectable despite 5 repeat freeze-thaw cycles. The detection of miRNA by quantitative PCR showed high reproducibility (>94% for intra-assay and >76% for inter-assay), high sensitivity (positive call 100% for CKD patients), broad dynamic range (8-log wide) and good linearity for quantification (R²>0.99). miR-29c and miR-200c showed different expression in different types of kidney disease. In summary, the presence of urinary exosomal miRNA was confirmed for patients with a diversity of chronic kidney disease. The conditions of urine collection, storage and miRNA detection determined in this study may be useful for future biomarker discovery efforts.     

Reduced Regional Homogeneity in Bilateral Frontostriatal System Relates to Higher Impulsivity Behavior in Codeine-Containing Cough Syrups Dependent Individuals

Background

In the past twenty years, codeine-containing cough syrups (CCS) was recognized as a new type of addictive drugs. However, the exact neurobiologic mechanisms underlying CCS-dependence are still ill-defined. The aims of this study are to identify CCS-related modulations of neural activity during the resting-state in CCS-dependent individuals and to investigate whether these changes of neural activity can be related to duration of CCS use, the first age of CCS use and impulse control deficits in CCS-dependent individuals. We also want to observe the impact of gray matter deficits on these functional results.

Methodology/Principal Findings

Thirty CCS-dependent individuals and 30 control subjects participated. Resting-state functional MRI was performed by using gradient-echo echo-planar imaging sequence. Regional homogeneity (ReHo) was calculated by using REST software. Voxel-based analysis of the ReHo maps between controls and CCS-dependent groups was performed using two-sample t tests (p<0.05, corrected for multiple comparisons). The Barratt Impulsiveness Scale 11 (BIS.11) was surveyed to assess participants'' impulsivity trait soon after MR examination. Abnormal clusters revealed by group comparison were extracted and correlated with impulsivity, duration of CCS use, and age of first CCS use. ReHo was diminished in the bilateral medial orbitofrontal cortex (mOFC) and left dorsal striatum in CCS-dependent individuals. There were negative correlations between mean ReHo in the bilateral medial OFC, left dorsal striatum and duration of CCS use, BIS.11 total scores, and the subscale of attentional impulsivity in CCS-dependent individuals. There was a significantly positive correlation between mean ReHo in the left dorsal striatum and age of first CCS use in CCS-dependent individuals. Importantly, these results still remain significant after statistically controlling for the regional gray matter deficits.

Conclusion

Resting-state abnormalities in CCS-dependent individuals revealed in the present study may further improve our understanding about the neural substrates of impulse control dysfunction in CCS-dependent individuals.     

Association between Ambient Temperature and Blood Pressure and Blood Pressure Regulators: 1831 Hypertensive Patients Followed Up for Three Years

Several studies have suggested an association between ambient air temperature and blood pressure. However, this has not been reliably confirmed by longitudinal studies. Also, whether the reaction to temperature stimulation is modified by other factors such as antihypertensive medication is rarely investigated. The present study explores the relationship between ambient temperature and blood pressure, without and with antihypertensive medication, in a study of 1,831 hypertensive patients followed up for three years, in two or four weekly check ups, accumulating 62,452 follow-up records. Both baseline and follow-up blood pressure showed an inverse association with ambient temperature, which explained 32.4% and 65.6% of variation of systolic blood pressure and diastolic blood pressure (P<0.05) respectively. The amplitude of individual blood pressure fluctuation with temperature throughout a year (a 29 degrees centigrade range) was 9.4/7.3 mmHg. Medication with angiotensin converting enzyme inhibitor benazepril attenuated the blood pressure fluctuation by 2.4/1.3 mmHg each year, though the inverse association of temperature and blood pressure remained. Gender, drinking behavior and body mass index were also found to modify the association between temperature and diastolic blood pressure. The results indicate that ambient temperature may negatively regulate blood pressure. Hypertensive patients should monitor and treat blood pressure more carefully in cold days, and it could be especially important for the males, thinner people and drinkers.     

Insulin Resistance Is an Independent Determinate of ED in Young Adult Men

Background

Insulin resistance (IR) triggers endothelial dysfunction, which contributes to erectile dysfunction (ED) and cardiovascular disease.

Aim

To evaluate whether IR was related to ED in young adult patients.

Methods

A total of 283 consecutive men complaining of ED at least six months were enrolled, with a full medical history, physical examination, and laboratory tests collected. Quantitative Insulin Sensitivity Check Index (QUICKI) was used to determine IR. The severity of ED was assessed by IIEF-5 questionnaire. Endothelial function was assessed by ultrasonographic examination of brachial artery flow mediated dilation (FMD).

Results

IR was detected in 52% patients. Subjects with IR had significant higher total cholesterol, triglycerides, low density lipoprotein-cholesterol (LDL-c), glycated haemoglobin (HBA1c), high sensitivity C-reactive protein (hs-CRP) and body mass index (BMI), but showed significant lower IIEF-5 score, FMD%, high density lipoprotein -cholesterol (HDL-c), testosterone, sex hormone binding globulin (SHBG) levels than patients without IR. Multiple regression analysis showed QUICKI and testosterone were independent predictors of IIEF-5 score. Furthermore, the incidence of IR was correlated with the severity of ED.

Conclusions

Compared with other CVFs, IR was found as the most prevalent in our subjects. Besides, IR was independently associated with ED and its severity, suggesting an adverse effect of insulin resistance on erectile function.