Evaluation of Copper Levels in Dental Calculus of OSF Patients with Chewing Dried Areca-Nut Quids in Hunan Province of Mainland China.

Dental calculus is a potential material that can be used for assessing chronic exposure to trace heavy metals in oral cavity as it is a long-term reservoir. The aim of this study was to investigate the correlation between dental calculus copper levels and risk of oral submucous fibrosis (OSF) due to chewing dried areca-nut quids in Mainland China. This study included 34 OSF (grade 1) sufferers with dried areca-nut quids chewing as the patient group and 23 healthy individuals without areca-nut chewing as the control group. The dental calculus sample was obtained from all 57 participants and evaluated by inductively coupled plasma mass spectrometry (ICP-MS) for dental calculus level of copper. This work revealed that the mean copper level of dental calculus was significantly higher in OSF (grade 1) sufferers with areca-nut chewing than those in healthy individuals without areca-nut chewing (p < 0.001). This work provided an evidence to support that there may be a positive correlation between elevated levels of copper in dental calculus caused by chewing dried areca-nut quids and an increased risk of developing OSF in Mainland China.

Gadd45b mediates environmental enrichment-induced neurogenesis in the SVZ of rats following ischemia stroke via BDNF.

Ischemic stroke is a major cause of mortality and disability. Subventricular zone (SVZ) neurogenesis following an ischemic stroke may be beneficial for improving the outcomes. Environmental enrichment (EE) has been reported to increase neurogenesis following stroke. Growth arrest and DNA-damage-inducible protein 45 ß (Gadd45b) is a crucial gene for activity-correlated neurogenesis in the adult hippocampus of mice. This study examined whether Gadd45b inhibition affects adult SVZ neurogenesis after an ischemic injury and explored the role of Gadd45b in EE-induced SVZ neurogenesis in adult male Sprague Dawley rats following middle cerebral artery occlusion (MCAO). Gadd45b expression was silenced by a lentivirus with RNA interference (RNAi). The 5-ethynyl-2-deoxyuridine (EdU) staining test was performed to detect cell proliferation. Gadd45b-RNAi after MCAO decreased SVZ proliferation and differentiation in the infarction boundary following ischemic injury, accompanied by the depressed expression of the brain-derived neurotrophic factor (BDNF). Treatment with EE following ischemic stroke upregulated Gadd45b and BDNF expressions and increased neurogenesis in the SVZ. Inhibition of Gadd45b markedly ameliorated the increased neurogenesis induced by EE. These data indicated that Gadd45b is related to SVZ neurogenesis following ischemic stroke, and Gadd45b mediates EE-induced neurogenesis via BDNF in the SVZ of rats following an ischemia stroke. These results implicate that Gadd45b can be a potential therapeutic target to enhance adult neurogenesis following cerebral ischemia.

A diubiquitin-based photoaffinity probe for profiling K27-linkage targeting deubiquitinases.

K27-linkage poly-ubiquitination plays important roles in DNA damage repair and autoimmunity. Identification of K27-linkage targeting deubiquitinases (DUBs) is essential for understanding their regulatory mechanisms. Here we report an aryl-azide-based photoaffinity diubiquitin (diUb) probe for profiling K27-linkage targeting DUBs. This probe shows high selectivity and sensitivity towards K27-linkage DUBs in vitro. It can also be used in cell lysate for identifying and probing K27-linkage targeting DUBs in real proteomes. Our work suggests that the photoaffinity-based strategy may provide a new useful approach for the construction of other isopeptide linkage targeting DUB probes.

Comparison of Auditory Middle-Latency Responses From Two Deconvolution Methods at 40 Hz.

GOAL: Auditory middle-latency responses (MLRs) are reported to be particularly susceptible to stimulation rate. Deconvolution methods are necessary to unwrap the overlapping responses at a high rate under the linear superposition assumption. This study aims to investigate and compare the MLR characteristics at high and conventional stimulation rates. METHODS: The characteristics were examined in healthy adults by using two closely related deconvolution paradigms, namely continuous-loop averaging deconvolution and multirate steady-state averaging deconvolution at a mean rate of 40 Hz, and a conventional low rate of 5 Hz. RESULTS: The morphology and stability of the MLRs can benefit from a high-rate stimulation. It appears that stimulation sequencing strategies of deconvolution methods exerted divergent rate effects on MLR characteristics, which might be associated with different adaptation mechanisms. CONCLUSION: MLRs obtained by two deconvolution methods and the conventional reference feature differently from one another. SIGNIFICANCE: These findings have critical implications in our current understanding of the rate effects on MLR characteristics which may inspire further studies to explore the characteristics of evoked responses at high rates and deconvolution paradigms.

Huwe1 interacts with Gadd45b under oxygen-glucose deprivation and reperfusion injury in primary Rat cortical neuronal cells.

BACKGROUND: Growth arrest and DNA-damage inducible protein 45 beta (Gadd45b) is serving as a neuronal activity sensor. Brain ischemia induces the expression of Gadd45b, which stimulates recovery after stroke and may play a protective role in cerebral ischemia. However, little is known of the molecular mechanisms of how Gadd45b expression regulated and the down-stream targets in brain ischemia. Here, using an oxygen-glucose deprivation and reperfusion (OGD/R) model, we identified Huwe1/Mule/ARF-BP1, a HECT domain containing ubiquitin ligase, involved in the control of Gadd45b protein level. In this study, we also investigated the role of Huwe1-Gadd45b mediated pathway in BDNF methylation. RESULTS: We found that the depletion of Huwe1 by lentivirus shRNA mediated interference significantly increased the expression of Gadd45b and BDNF at 24 h after OGD. Moreover, treatment with Cycloheximide (CHX) inhibited endogenous expression of Gadd45b, and promoted expression of Gadd45b after co-treated with lentivirus shRNA-Huwe1. Inhibition of Gadd45b by lentivirus shRNA decreased the expression levels of brain derived neurotrophic factor (BDNF) and phosphorylated cAMP response element-binding protein (p-CREB) pathway, while inhibition of Huwe1 increased the expression levels of BDNF and p-CREB. Moreover, shRNA-Huwe1 treatment decreased the methylation level of the fifth CpG islands (123 bp apart from BDNF IXa), while shRNA-Gadd45b treatment increased the methylation level of the forth CpG islands (105 bp apart from BDNF IXa). CONCLUSIONS: These findings suggested that Huwe1 involved in the regulation of Gadd45b expression under OGD/R, providing a novel route for neurons following cerebral ischemia-reperfusion injury. It also indicated that the methylation of BDNF IXa was affected by Gadd45b as well as Huwe1 in the OGD/R model.

Simulation on the Comparison of Steady-State Responses Synthesized by Transient Templates Based on Superposition Hypothesis.

The generation of auditory-evoked steady-state responses (SSRs) is associated with the linear superposition of transient auditory-evoked potentials (AEPs) that cannot be directly observed. A straightforward way to justify the superposition hypothesis is the use of synthesized SSRs by a transient AEP under a predefined condition based on the forward process of this hypothesis. However, little is known about the inverse relation between the transient AEP and its synthetic SSR, which makes the interpretation of the latter less convincible because it may not necessarily underlie the true solution. In this study, we chose two pairs of AEPs from the conventional and deconvolution paradigms, which represent the homo-AEPs from a homogenous group and the hetero-AEPs from two heterogeneous groups. Both pairs of AEPs were used as templates to synthesize SSRs at rates of 20-120 Hz. The peak-peak amplitudes and the differences between the paired waves were measured. Although amplitude enhancement occurred at ~40 Hz, comparisons between the available waves demonstrated that the relative differences of the synthetic SSRs could be dramatically larger at other rates. Moreover, two virtually identical SSRs may come from clearly different AEPs. These results suggested inconsistent relationships between the AEPs and their corresponding SSRs over the tested rates.

Gadd45b is a novel mediator of neuronal apoptosis in ischemic stroke.

Apoptosis plays an essential role in ischemic stroke pathogenesis. Research on the process of neuronal apoptosis in models of ischemic brain injury seems promising. The role of growth arrest and DNA-damage-inducible protein 45 beta (Gadd45b) in brain ischemia has not been fully examined to date. This study aims to investigate the function of Gadd45b in ischemia-induced apoptosis. Adult male Sprague-Dawley rats were subjected to brain ischemia by middle cerebral artery occlusion (MCAO). RNA interference (RNAi) system, which is mediated by a lentiviral vector (LV), was stereotaxically injected into the ipsilateral lateral ventricle to knockdown Gadd45b expression. Neurologic scores and infarct volumes were assessed 24 h after reperfusion. Apoptosis-related molecules were studied using immunohistochemistry and Western blot analysis. We found that Gadd45b-RNAi significantly increased infarct volumes and worsened the outcome of transient focal cerebral ischemia. Gadd45b-RNAi also significantly increased neuronal apoptosis as indicated by increased levels of Bax and active caspase-3, and decreased levels of Bcl-2. These results indicate that Gadd45b is a beneficial mediator of neuronal apoptosis.

Gadd45b Mediates Axonal Plasticity and Subsequent Functional Recovery After Experimental Stroke in Rats.

Stroke causes devastating and irreversible losses of neurological function with subsequent slow and incomplete recovery of lost brain functions, because of the brain's limited capacity for brain plasticity. Growth arrest and DNA-damage-inducible protein 45 beta (Gadd45b) has recently been demonstrated as a candidate plasticity-related gene, making it an excellent candidate molecule that has therapeutic potential. Here, we examine whether in vivo blockage of Gadd45b affects axonal plasticity and subsequent functional recovery after focal brain infarction. Adult male Sprague-Dawley rats were subjected to cerebral ischemia by middle cerebral artery occlusion (MCAO). We adopted RNA interference (RNAi) mediated by a lentiviral vector (LV) as a means of suppressing the expression of Gadd45b. Functional recovery was assessed with a battery of tests that measured skilled forelimb reaching and forelimb balance controlling. Axonal reorganization at the level of the red nucleus was revealed by anatomical studies. Axonal regeneration was measured by elevated expression of growth-associated protein 43 (GAP-43). The levels of brain-derived neurotrophic factor (BDNF), cyclic AMP (cAMP), protein kinase A (PKA), and Rho-kinase (ROCK) were determined. Gadd45b-RNAi significantly inhibited axonal plasticity (axonal regeneration and axonal reorganization) after MCAO. This inhibition was paralleled by worse functional recovery performance on several behavioral measures. Gadd45b-RNAi also significantly decreased the expression levels of both BDNF and cAMP/PKA/phosphorylated cAMP response element-binding protein (pCREB) pathway and promoted ROCK expression. We conclude that Gadd45b stimulates recovery after stroke by enhancing axonal plasticity required for brain repair. Pharmacological targeting of Gadd45b provides new opportunities for stroke treatment.

Copper-catalyzed decarboxylative coupling of alkynyl carboxylates with 1,1-dibromo-1-alkenes.

A copper-catalyzed decarboxylative coupling reaction of potassium alkynyl carboxylates with 1,1-dibromo-1-alkenes was developed for the synthesis of unsymmetrical 1,3-diyne and 1,3,5-triyne derivatives. Diverse aryl, alkenyl, alkynyl, and alkyl substituted 1,1-dibromo-1-alkenes can react smoothly with aryl and alkyl substituted propiolates to produce unsymmetrical 1,3-diynes and 1,3,5-triynes with high selectivity and good functional group compatibility.

Mathematical model of phosphatidylinositol-4,5-bisphosphate hydrolysis mediated by epidermal growth factor receptor generating diacylglycerol.

Phosphatidylinositol-4,5-bisphosphate (PIP2) is hydrolyzed in response to the tyrosine phosphorylation of the epidermal growth factor receptor (EGFR) and plays an important role in regulating cell proliferation and differentiation through the generation of second messengers diacylglycerol (DAG) and trisphosphate inositol (IP3) which lead to the activation of protein kinase C (PKC) and increased levels of intracellular calcium, respectively. In the paper, a mathematical model was established to simulate the accumulation of DAG due to PIP2 hydrolysis mediated by EGFR. Molecular mechanisms between DAG, PIP2, EGFR and phosphatidylinositol transfer protein (PITP) were explained successfully, and positive cooperativity which existed between phospholipase C-gamma1 (PLC-gamma1) and PIP2 was also explained. In the model the effects of parameters on simulation of PIP2 hydrolysis were analyzed and the efficacies of some molecular intervention strategies were predicted. To test the coherence between the model and the biological response to epidermal growth factor (EGF) in cells, the levels of DAG and the tyrosine phosphorylation-EGFRs in NIH3T3 mouse embryonic fibroblast (MEF) were determined by biochemical experiments which showed that the accumulation of DAG was a sigmoidal function of phosphorylation-EGFR concentration, and the consistency between the mathematical model and experimental results was confirmed. In brief, this mathematical model provided a new idea for the further study of the dynamic change of biological characteristics in inositol phospholipid hydrolysis, predicting the efficacy of molecular intervention and the relationship between the metabolisms of inositol phospholipid and other signal transduction pathways.

[Analysis and realization of the method for predicting physical pathways of allosteric communication in a protein family].

A fundamental goal in signal transduction study is to understand allosteric communication. The authors present hereby a statistical coupling analysis method (developed by Steve W. Lockless etc.) for quantitative mapping of the global network of amino acid positions in a protein and predicting a set of energetically coupled positions, which may constitute the physical pathways of allosteric communication in a protein family. Based on MATLAB, the authors realized this method and created histograms of amino acid distributions for all 63 395 entries (as of April 2004) in the Swiss-Prot database of eukaryotic proteins and calculated the mean values. The result was similar to that calculated by Steve W. Lockless in October 1998.

[Mathematical model of epidermal growth factor receptor-mediated lipid phosphatidylinositol(4,5)-bisphosphate hydrolyzation by phospholipase C-gamma1 activity].

OBJECTIVE: To investigate the dynamic characteristics of lipid phosphatidylinositol (4,5)-bisphosphate (PIP(2)) in plasma membrane hydrolyzed by phospholipase C-gamma1 in epidermal growth factor receptor(EGFR)-mediated signal pathway. METHODS: A mathematical model based on the law of mass action was established with differential equations to simulate metabolizable pathway of PIP(2). RESULTS: Differential equations of the key product concentration during hydrolysis of PIP(2) were formulated, and the effects of the parameters on these hydrolyzed products analyzed. CONCLUSION: This mathematical model provides foundation for further investigation of the dynamic changes of biological characteristics and the relations between the key product concentrations in PIP2 hydrolysis.