HBV promotes its replication by up-regulating RAD51C gene expression.

Chronic hepatitis B virus (HBV) infection is a major cause of hepatocellular carcinoma (HCC), pegylated-interferon-α(PEG-IFNα) and long-term nucleos(t)ide analogs (NUCs) are mainly drugs used to treat HBV infection, but the effectiveness is unsatisfactory in different populations, the exploration of novel therapeutic approaches is necessary. RAD51C is associated with DNA damage repair and plays an important role in the development and progression of tumors. Early cDNA microarray results showed that RAD51C expression was significantly increased in HBV-infected HCC cells, however, the relationship between HBV infection and abnormal expression of RAD51C has not been reported. Therefore, we conducted RT-PCR, western blot, Co-immunoprecipitation(Co-IP), and immunofluorescence(IF) to detect HBV-RAD51C interaction in RAD51C overexpression or interfering HCC cells. Our results showed that RAD51C and HBV X protein(HBX) produced a direct interaction in the nucleus, the HBV infection of HCC cells promoted RAD51C expression, and the increased expression of RAD51C promoted HBV replication. This indicated that RAD51C is closely related to the occurrence and development of HCC caused by HBV infection, and may bring a breakthrough in the the prevention and treatment study of HCC.

Analysis of Common Respiratory Infected Pathogens in 3100 Children after the Coronavirus Disease 2019 Pandemic.

OBJECTIVE: To investigate the epidemiological features in children after the coronavirus disease 2019 (COVID-19) pandemic. METHODS: This study collected throat swabs and serum samples from hospitalized pediatric patients of Renmin Hospital of Wuhan University, Wuhan, Hubei province, China before and after the COVID-19 pandemic. Respiratory infected pathogens [adenovirus (ADV), influenza virus A/B (Flu A/B), parainfluenza virus 1/2/3 (PIV1/2/3), respiratory syncytial virus (RSV), Mycoplasma pneumoniae (MP), and Chlamydia pneumoniae (CP)] were detected. The pathogens, age, and gender were used to analyze the epidemiological features in children after the COVID-19 pandemic. RESULTS: The pathogen detection rate was significantly higher in females than in males (P<0.05), and the infection of PIV1 and MP was mainly manifested. After the COVID-19 pandemic, PIV1, PIV3, RSV, and MP had statistically different detection rates among the age groups (P<0.05), and was mainly detected in patients aged 0-6 years, 0-3 years, 0-3 years, and 1-6 years, respectively. When comparing before the COVID-19 pandemic, the total detection rate of common respiratory pathogens was lower (P<0.05). Except for the increase in the detection rate of PIV1 and CP, the infection rate of other pathogens had almost decreased. CONCLUSION: The prevention and control measures for the COVID-19 pandemic effectively changed the epidemiological features of common respiratory tract infectious diseases in pediatric children.

Dynamic Neural Network Changes Revealed by Voxel-Based Functional Connectivity Strength in Left Basal Ganglia Ischemic Stroke.

OBJECTIVE: This study intends to track whole-brain functional connectivity strength (FCS) changes and the lateralization index (LI) in left basal ganglia (BG) ischemic stroke patients. METHODS: Twenty-five patients (N = 25; aged 52.73 ± 10.51 years) with five visits at <7, 14, 30, 90, and 180 days and 26 healthy controls (HCs; N = 26; 51.84 ± 8.06 years) were examined with resting-state functional magnetic resonance imaging (rs-fMRI) and motor function testing. FCS and LI were calculated through constructing the voxel-based brain functional network. One-way analysis of covariance (ANOVA) was first performed to obtain longitudinal FCS and LI changes in patients among the five visits (Bonferroni corrected, P < 0.05). Then, pairwise comparisons of FCS and LI were obtained during the five visits, and the two-sample t test was used to examine between-group differences in FCS [family-wise error (FWE) corrected, P < 0.05] and LI. Correlations between connectivity metrics (FCS and LI) and motor function were further assessed. RESULTS: Compared to HCs, decreased FCS in the patients localized in the calcarine and inferior occipital gyrus (IOG), while increased FCS gathered in the middle prefrontal cortex (MPFC), middle frontal gyrus, and insula (P < 0.05). The LI and FCS of patients first decreased and then increased, which showed significant differences compared with HCs (P < 0.05) and demonstrated a transition at the 30-day visit. Additionally, LI at the third visit was significantly different from those at the other visits (P < 0.05). No significant longitudinal correlations were observed between motor function and FCS or LI (P > 0.05). CONCLUSION: Focal ischemic stroke in the left BG leads to extensive alterations in the FCS. Strong plasticity in the functional networks could be reorganized in different temporal dynamics to facilitate motor recovery after BG stroke, contribute to diagnosing the disease course, and estimate the intervention treatment.

Assessment of MRI-based anomalous diffusion changes in brain ischemic stroke with a fractional motion model.

The actual diffusion process in human brain has been shown to be anomalous comparing to that predicted with traditional diffusion MRI (dMRI) theory. Recently, dMRI based on fractional motion (FM) model has demonstrated the potential to accurately describe anomalous diffusion in vivo. In this work, we explored the potential value of FM model-based dMRI in quantificational identification of ischemic stroke and compared that with the traditional apparent diffusion coefficient (ADC). We included 23 acute stroke patients, 8 of whom finished a follow-up scan, and 22 matched healthy controls. The dMRI images were acquired by using a Stejskal-Tanner single-shot spin-echo echo-planar-imaging sequence (diffusion gradients were applied in three orthogonal directions with 25 non-zero b values ranging from 248 to 4474 s/mm2) at 3.0 T MRI. We calculated the coefficient of variation (CV) for FM-related parameters in stroke lesions, and compared the mean values for FM-related parameters and ADC by using two-sample t-tests. Correlation analysis was achieved using Pearson correlation coefficient test. In acute stroke lesions, CV for FM-related parameters showed significant increase compared with normal tissues (P < 0.01), while those of ADC didn't appear statistical difference. Mean values for FM-related parameters showed significant decrease in acute lesion (P < 0.01) and their changing pattern during follow-up was positively correlated with ADC (P < 0.005). Our results initially verified the utility of the FM-model in detecting ischemic stroke compared with traditional dMRI.

MEPO promotes neurogenesis and angiogenesis but suppresses gliogenesis in mice with acute ischemic stroke.

Previously study has proved the non-erythropoietic mutant erythropoietin (MEPO) exerted neuroprotective effects against ischemic cerebral injury, with an efficacy similar to that of wild-type EPO. This study investigates its effects on neurogenesis, angiogenesis, and gliogenesis in cerebral ischemic mice. Male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) and reperfusion. EPO (5000 U/kg), MEPO (5000 U/kg) or equal volume of normal saline was injected intraperitoneally. Neurological function was evaluated by Rota-rod test, Neurological severity scores (NSS) and Adhesive removal test. After ischemia and reperfusion (I/R), the survival rate, brain tissue loss, neurogenesis, angiogenesis and gliogenesis were detected by Nissl staining, Immunofluorescence and Western blot, respectively. The results shown that MEPO significantly increased survival rate, reduced brain tissue loss, and improved neurological function after MCAO (P < 0.05). Furthermore, MEPO obviously enhanced the proliferation of neuronal precursors (DCX) and promoted its differentiation into mature neurons (NeuN) (P < 0.05). In addition, compared to normal saline treatment mice, MEPO increased the number of BrdU-positive cells in the cerebral vasculature (P < 0.05). Whereas, MEPO treatment also reduced the numbers of newly generated astrocytes (GFAP) and microglia (Iba1) (P < 0.05). Among all the tests in this study, there was no significant difference between EPO group and MEPO group. Taken together, MEPO promoted the regeneration of neurons and blood vessels in peripheral area of infarction, and suppressed the gliogenesis, thus promoting neurogenesis, improving neurological function and survival rate. Our findings suggest that the MEPO may be a therapeutic drug for ischemic stroke intervention.

Effects of time delays on the therapeutic outcomes of intravenous thrombolysis for acute ischemic stroke in the posterior circulation: An observational study.

OBJECTIVES: We aim to demonstrate the effects of time delays on the therapeutic outcomes of intravenous thrombolysis (IVT) in acute posterior circulation stroke (PCS) patients. METHODS: Consecutive PCS cases treated with IVT alone were retrospectively examined. The primary end point was set to be a favorable outcome (modified Rankin Scale [mRS] ≤2) at 3 months, and angiographic recanalization was set to be the secondary outcome. RESULTS: A total of 95 PCS cases with IVT were recruited. The patients with favorable outcomes and those without favorable outcomes had similar baseline characteristics, except for significantly lower National Institute of Health Stroke Scale (NIHSS) scores (5 vs. 12, respectively; p < 0.001) and less hyperdense basilar artery signs in head CTs (26.5% vs. 70.4%, respectively; p < 0.001) for those with favorable outcomes. For patients with an onset-to-treatment time (OTT) of 0-90 min (n = 5), 91-180 min (n = 38), 181-270 min (n = 37), or ≧271 min (n = 15), the rate of favorable outcome was 100.0%, 71.1%, 67.6%, or 73.3%, respectively, and the Cochran-Armitage trend test showed no linear trend between the OTT and the clinical prognosis of IVT in PCS (p = 0.501) patients. In addition, the rates of recanalization were 100.0%, 68.4%, 64.9%, and 46.7%, and the Cochran-Armitage trend test suggested a linear trend between the OTT and recanalization (p = 0.046); that is, the proportion of PCS patients who underwent recanalization decreased with increasing OTTs. In the multivariate logistic regression analysis, after adjusting for confounding factors with p â‰¦ 0.20 in the univariate analysis, baseline NIHSS scores and hyperdense basilar artery signs were negatively associated with favorable outcomes, with odds ratios (OR) of 0.884 (95% confidence interval [CI], 0.804-0.971; p = 0.010) and 0.208 (95% CI, 0.062-0.693; p = 0.011), respectively. In addition, there was a negative association between recanalization, OTTs (OR, 0.993, 95% CI, 0.987-0.999; p = 0.029), and baseline NIHSS scores (OR, 0.881, 95% CI, 0.802-0.967; p = 0.008). CONCLUSION: Irrespective of stroke severity, the therapeutic effects of recanalization after IVT decreased significantly with longer time delays in PCS patients.

Homotopic Connectivity in Early Pontine Infarction Predicts Late Motor Recovery.

Connectivity-based methods are essential to explore brain reorganization after a stroke and to provide meaningful predictors for late motor recovery. We aim to investigate the homotopic connectivity alterations during a 180-day follow-up of patients with pontine infarction to find an early biomarker for late motor recovery prediction. In our study, resting-state functional MRI was performed in 15 patients (11 males, 4 females, age: 57.87 ± 6.50) with unilateral pontine infarction and impaired motor function during a period of 6 months (7, 14, 30, 90, and 180 days after stroke onset). Clinical neurological assessments were performed using the Fugl-Meyer scale (FM).15 matched healthy volunteers were also recruited. Whole-brain functional homotopy in each individual scan was measured by voxel-mirrored homotopic connectivity (VMHC) values. Group-level analysis was performed between stroke patients and normal controls. A Pearson correlation was performed to evaluate correlations between early VMHC and the subsequent 4 visits for behavioral measures during day 14 to day 180. We found in early stroke (within 7 days after onset), decreased VMHC was detected in the bilateral precentral and postcentral gyrus and precuneus/posterior cingulate cortex (PCC), while increased VMHC was found in the hippocampus/amygdala and frontal pole (P < 0.01). During follow-up, VMHC in the precentral and postcentral gyrus increased to the normal level from day 90, while VMHC in the precuneus/PCC presented decreased intensity during all time points (P < 0.05). The hippocampus/amygdala and frontal pole presented a higher level of VMHC during all time points (P < 0.05). Negative correlation was found between early VMHC in the hippocampus/amygdala with FM on day 14 (r = -0.59, p = 0.021), day 30 (r = -0.643, p = 0.01), day 90 (r = -0.693, p = 0.004), and day 180 (r = -0.668, p = 0.007). Furthermore, early VMHC in the frontal pole was negatively correlated with FM scores on day 30 (r = -0.662, p = 0.013), day 90 (r = -0.606, p = 0.017), and day 180 (r = -0.552, p = 0.033). Our study demonstrated the potential utility of early homotopic connectivity for prediction of late motor recovery in pontine infarction.

[Rapid FTIR-ATR Method for the Quantification of Bitumen Property].

The quality of bitumen directly affects road performance and road life. Traditional analytical methods-for wax content, softening point and penetration of bitumen are tedious and time-consuming. A new fast method, with which the three properties can be determined at same time, is proposed in this paper. The spectra of 220 bitumen were collected and their wax content, softening point and penetration data were determined according to the standard JTJ052-2000. The quantitative calibration models for wax content, softening point and penetration were established using partial least squares (PLS), with SECV 0.13, 0.88, 3.18 and SEP 0.14, 1.06, 3.90, less than the reproducibility error stipulated in the standard method. Three samples were in random selected to test the repeatability, the results met the precision requirement of the standard method. With its advantages of better repeatability, fast, easy operation, the new method can be used as an alternative for the determination of wax content, softening point and penetration of bitumen.

Generalization of the Right Acute Stroke Prevention Strategies in Reducing in-Hospital Delays.

The aim of this study was to reduce the door-to-needle (DTN) time of intravenous thrombolysis (IVT) in acute ischemic stroke (AIS) through a comprehensive, hospital-based implementation strategy. The intervention involved a systemic literature review, identifying barriers to rapid IVT treatment at our hospital, setting target DTN time intervals, and building an evolving model for IVT candidate selection. The rate of non-in-hospital delay (DTN time ≤ 60 min) was set as the primary endpoint. A total of 348 IVT cases were enrolled in the study (202 and 146 in the pre- and post-intervention group, respectively). The median age was 61 years in both groups; 25.2% and 26.7% of patients in the pre- and post-intervention groups, respectively, were female. The post-intervention group had higher rates of dyslipidemia and minor stroke [defined as National Institutes of Health Stroke Scale (NIHSS) ≤ 3]; less frequent atrial fibrillation; higher numbers of current smokers, heavy drinkers, referrals, and multi-model head imaging cases; and lower NIHSS scores and blood sugar level (all P < 0.05). All parameters including DTN, door-to-examination, door-to-imaging, door-to-laboratory, and final-test-to-needle times were improved post-intervention (all P < 0.05), with net reductions of 63, 2, 4, 28, and 23 min, respectively. The rates of DTN time ≤ 60 min and onset-to-needle time ≤ 180 min were significantly improved by the intervention (pre: 9.9% vs. post: 60.3%; P < 0.001 and pre: 23.3% vs. post: 53.4%; P < 0.001, respectively), which was accompanied by an increase in the rate of neurological improvement (pre: 45.5% vs. post: 59.6%; P = 0.010), while there was no change in incidence of mortality or systemic intracranial hemorrhage at discharge (both P > 0.05). These findings indicate that it is possible to achieve a DTN time ≤ 60 min for up to 60% of hospitals in the current Chinese system, and that this logistical change can yield a notable improvement in the outcome of IVT patients.

Factors Associated with In-Hospital Delay in Intravenous Thrombolysis for Acute Ischemic Stroke: Lessons from China.

In-hospital delay reduces the benefit of intravenous thrombolysis (IVT) in acute ischemic stroke (AIS), while factors affecting in-hospital delay are less well known in Chinese. We are aiming at determining the specific factors associated with in-hospital delay through a hospital based cohort. In-hospital delay was defined as door-to-needle time (DTN) ≥60 min (standard delay criteria) or ≥75% percentile of all DTNs (severe delay criteria). Demographic data, time intervals [onset-to-door time (OTD), DTN, door-to-examination time (DTE), door-to-imaging time (DTI), door-to-laboratory time (DTL) and final-test-to-needle time (FTN, the time interval between the time obtaining the result of the last screening test and the needle time)], medical history and additional variables were calculated using Mann-Whitney U or Pearson Chi-Square tests for group comparison, and multivariate linear regression analysis was performed to identify independent variables of in-hospital delay. A total of 202 IVT cases were enrolled. The median age was 61 years and 25.2% were female. The cutoff points for the upper quartile of DTN (severe delay criteria) was 135 min.When compared with the reference group without in-hospital delay, older age, shorter OTD and less referral were found in the standard delay group and male sex, presence with transient ischemic attacks or rapidly improving symptom, and with multi-model CT imaging were more frequent in the severe delay group. In the multivariate linear regression analysis, FTN (P<0.001) and DTL (P = 0.002) were significantly associated with standard delay; while DTE (P = 0.005), DTI (P = 0.033), DTL (P<0.001), and FTN (P<0.001) were positively associated with severe delay. There was not a significant change in the trend of DTNs during the study period (P = 0.054). In-hospital delay was due to multifactors in China, in which time delays of decision-making process and laboratory tests contributed the most. Efforts aiming at reducing the delay should be focused on the optimization for the items of screening tests and improvement of the pathway organization.

Intravenous versus intra-arterial thrombolysis in ischemic stroke: a systematic review and meta-analysis.

BACKGROUND: Reperfusion following ischemic stroke can be attained by either intravenous thrombolysis (IVT) or intra-arterial thrombolysis (IAT). Only a limited number of randomized prospective studies have compared the efficacy and safety of IVT and IAT. This meta-analysis investigated possible clinical benefits of IAT relative to IVT in patients with acute ischemic stroke. METHODS: We searched the PubMed, Cochrane, and Google Scholar databases through October 2013 for manuscripts that describe the findings of randomized controlled or prospective studies that evaluated the outcomes of patients with ischemic stroke who were treated with IVT or IAT. The clinical outcome measures were score on the modified Rankin scale (mRS) and mortality at 90 days. A favorable outcome was defined as an mRS score of 0 to 2. RESULTS: For the mRS, the combined odds ratio (OR) of 3.28 (95% confidence interval (CI), 1.91 to 5.65, P < 0.001) indicated that patients who received IAT had a significantly higher chance for a favorable outcome than did those who received IVT. For mortality, the OR indicated that IAT therapy significantly reduced the proportion of patients who died within 90 days of the procedure (combined OR, 0.40; 95%CI, 0.17 to 0.92; P = 0.032). CONCLUSION: This meta-analysis determined that IAT conferred a significantly greater probability of achieving a favorable outcome compared with IVT. There was also a significant difference in mortality rates between IAT and IVT. The studies included in this analysis were small and heterogeneous; therefore, larger randomized prospective clinical studies are necessary to further investigate this issue.

Association between clinical features and prognosis of patients with limb-shaking transient ischemic attack.

OBJECTIVE: This review aims to illustrate the relationship between clinical features and the prognosis of patients with limb-shaking transient ischemic attack (LS-TIA). DATA SOURCES: Relevant articles published in two main Chinese medical periodical databases (China National Knowledge Infrastructure and China Science Periodical Database) from 1986 to June 2013 were identified with keywords "limb shaking" and "transient ischemic attack". STUDY SELECTION: Original articles and case reports about LS-TIA were selected. RESULTS: A total of 63 cases collected from 19 articles were included in the pooled analysis. LS-TIA presented in two cerebrovascular diseases, of which atherosclerotic high-grade stenosis or occlusion in carotid artery system and moyamoya disease formed 95.2% and 4.8%, respectively. Of 63 patients, 11 (17.5%) were once misdiagnosed as epileptic and prescribed useless antiepilepsy drugs. The multivariable Logistic regression model showed a significant protective effect of patients with revascularization therapy on prognosis, compared with patients treated with drugs (odds ratio 0.20, 95% CI 0.05-0.74, P = 0.016). CONCLUSIONS: Chronic carotid artery system hypoperfusion can induce limb(s) shaking, followed by high possibility of ischemic stroke in the same brain territorial. Revascularization of the responsible artery may work better than conservative drug-based therapy.

[Case constitution and medication intention of bipolar disordered outpatients at two grade IIIa hospitals in Beijing].

OBJECTIVE: To acquire the case constitution of bipolar disordered (BPD) in mood disordered (MD) outpatients at two local Beijing hospitals to understand the case constitution and medication intention of clinical psychiatrists in terms of differentiation and treatment of BPD. METHODS: All psychiatrists at Anding Hospital and neurological physicians at Xuanwu Hospital were surveyed by self-rated questionnaires and the analysis focused on the composition of proportions of BPD cases out of MD patients. The items included estimated ratio of BPD cases, doctors' intention of drug prescription and clinical therapeutic regimen for treatment of BPD. RESULTS: (1) BPD ratio in MD outpatients of two hospitals were 41.79% and 12.24% respectively; (2) Doctor's ratio who estimated BPD ratio in MD cases < 40% were 60% and 100% respectively; (3) 100% psychiatrists at Beijing Anding Hospital and 72.22% neurological physicians at Beijing Xuanwu Hospital prescribed antidepressant to BPD cases; (4) Doctor's ratio who adopted therapeutic schedule of 'antidepressant + mood stabilizer' or 'antidepressant + mood stabilizer + antipsychotic' agents for BPD were 100% and 66.67% respectively. CONCLUSION: Regardless of mental specialized hospital or general hospital, the physicians should pay great attention to the differentiation of BPD and the rationality of drug prescription.

[Intravenous thrombolysis directed by whole-brain computed tomographic perfusion:a case-control study].

OBJECTIVE: To explore the efficacy and safety of intravenous thrombolysis (IVT) directed by whole-brain computed tomographic perfusion (CTP). METHODS: A total of 65 patients with acute ischemic stroke at our hospital during the period of April 2011 to April 2013, selected in accordance with the established CTP or TTW standard (0 to 3.0 h and 3.0 to 4.5 h) for IVT were included for analysis. The primary endpoint events were Barthel index (BI) and the rate of serious adverse events at 14 days post-onset. The latter included mortality and symptomatic intracerebral hemorrhage (ICH). And secondary indicators included the incidence of reperfusion, recanalization, ICH and neurological improvement at Day 14, as well as time indicators, such as onset-to-door time (ODT), door-to-treatment time (DTT) and onset-to-treatment time (OTT). Statistical calculations for continuous variables were compared with t or Mann-Whitney U test. And other comparisons were made with Pearson Chi-square or Fisher's exact test. RESULTS: Twenty-five and 40 cases with acute ischemic stroke were enrolled according to CTP or TTW standard for IVT respectively. Baseline characteristics, including age, gender, risk factors, blood pressure, blood sugar, National Institute of Health stroke scale (NIHSS) and drug dose showed no significant difference among groups. DTT and OTT in CTP group were significantly longer than those of the 0 to 3.0 h subgroup, while similar with those of the 3.0 to 4.5 h subgroup. Interestingly, consistent with a significant higher rate of transferring for consultation in the CTP group comparing with the TTW group (52.0% vs 25.0%, P = 0.03), the rate was also significantly higher than the 0 to 3.0 h subgroup (52.0% vs 7.7%, P = 0.02), but not significantly higher than the 3.0 to 4.5 subgroup. Both primary endpoint events and secondary outcome measures among three groups showed no significant differences. As for secondary outcome measures, CTP group had a higher recanalization than the 3.0 to 4.5 h subgroup (52.0% vs 37.0%, P = 0.28) and there was a trend toward significance. CTP excluded 58 cases, including 20 proved cases of malignant infarction on magnetic resonance imaging. CONCLUSION: CTP is able to select reasonable candidates for IVT in an extended time window with effectiveness and safety comparable to TTW standard. Furthermore, it is quicker and more sensitive than TTW standard in detecting malignant infarction.

[Relationship between computed tomography perfusion imaging and prognosis in hyperacute cerebral infarction].

OBJECTIVE: To explore the diagnostic valves of computed tomography perfusion imaging (CTP) in hyperacute cerebral infarction patients and examine the correlation of time period from symptom onset to examination and CTP parameters. METHODS: Non-enhancement CT and CTP were performed on 75 patients with acute cerebral infarction of internal carotid system within 8 hours of symptom onset at our department from January 2006 to May 2008. National Institute of Health Stroke Scale score (NIHSS), Barthel index (BI) and modified Rankin scale (mRS) were assessed at the same day, days 14 and 90 after stroke onset respectively for neurological function impairment, activity of daily living and extent of disability in prognosis. RESULTS: (1) All CTP parameters in ischemic region had no correlation with time period from symptom onset to examination (P > 0.05). No significant differences were found between the patients with > 3 hours and < 3 hours after stroke onset in terms of the above parameters; (2) the areas of CBF (cerebral blood flow) on ischemic region significantly correlated with NIHSS at the day of symptom onset (r = 0.391, P < 0.001), Day 14 (r = 0.564, P < 0.001) and Day 90 (r = 0.549, P < 0.001) after symptom onset. CBV (cerebral blood volume) and TTP (time-to-peak) on ischemic region significantly correlated with the evaluation indices of predicting clinical outcomes at the day of symptom onset, Days 14 and 90 (P < 0.01). CBF, CBV, rCBF (regional CBF) and rCBV (regional CBV) correlated only with some of the clinical outcome scores. CONCLUSION: Time period after symptom onset can not reflect the ischemic extent and volume of cerebral infarction. But CTP may evaluate the severity and prognosis of acute cerebral infarction patients. The area of abnormal perfusion is the most sensitive parameter.

Characterization of copper binding to the peptide amyloid-beta(1-16) associated with Alzheimer's disease.

Amyloid-beta peptide (Abeta) is the principal constituent of plaques associated with Alzheimer's disease (AD) and is thought to be responsible for the neurotoxicity associated with the disease. Copper binding to Abeta has been hypothesized to play an important role in the neruotoxicity of Abeta and free radical damage, and Cu2+ chelators represent a possible therapy for AD. However, many properties of copper binding to Abeta have not been elucidated clearly, and the location of copper binding sites on Abeta is also in controversy. Here we have used a range of spectroscopic techniques to characterize the coordination of Cu2+ to Abeta(1-16) in solution. Electrospray ionization mass spectrometry shows that copper binds to Abeta(1-16) at pH 6.0 and 7.0. The mode of copper binding is highly pH dependent. Circular dichroism results indicate that copper chelation causes a structural transition of Abeta(1-16). UV-visible absorption spectra suggest that three nitrogen donor ligands and one oxygen donor ligand (3N1O) in Abeta(1-16) may form a type II square-planar coordination geometry with Cu2+. By means of fluorescence spectroscopy, competition studies with glycine and L-histidine show that copper binds to Abeta(1-16) with an affinity of Ka approximately 10(7) M(-1) at pH 7.8. Besides His6, His13, and His14, Tyr10 is also involved in the coordination of Abeta(1-16) with Cu2+, which is supported by 1H NMR and UV-visible absorption spectra. Evidence for the link between Cu2+ and AD is growing, and this work has made a significant contribution to understanding the mode of copper binding to Abeta(1-16) in solution.

Binding of copper (II) ion to an Alzheimer's tau peptide as revealed by MALDI-TOF MS, CD, and NMR.

The tau protein plays an important role in some neurodegenerative diseases including Alzheimer's disease (AD). Neurofibrillary tangles (NFTs), a biological marker for AD, are aggregates of bundles of paired helical filaments (PHFs). In general, the alpha-sheet structure favors aberrant protein aggregates. However, some reports have shown that the alpha-helix structure is capable of triggering the formation of aberrant tau protein aggregates and PHFs have a high alpha-helix content. In addition, the third repeat fragment in the four-repeat microtubule-binding domain of the tau protein (residues 306-336: VQIVYKPVDLSKVTSKCGSLGNIHHKPGGGQ, according to the longest tau protein) adopts a helical structure in trifluoroethanol (TFE) and may be a self-assembly model in the tau protein. In the human brain, there is a very small quantity of copper, which performs an important function. In our study, by means of matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS), circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopy, the binding properties of copper (II) ion to the R3 peptide derived from the third repeat fragment (residues 318-335: VTSKCGSLGNIHHKPGGG) have been investigated. The results show that copper ions bind to the R3 peptide. CD spectra, ultraviolet (UV)-visible absorption spectra, and MALDI-TOF MS show pH dependence and stoichiometry of Cu2+ binding. Furthermore, CD spectra and NMR spectroscopy elucidate the copper binding sites located in the R3 peptide. Finally, CD spectra reveal that the R3 peptide adopts a mixture structure of random structures, alpha-helices, and beta-turns in aqueous solutions at physiological pH. At pH 7.5, the addition of 0.25 mol eq of Cu2+ induces the conformational change from the mixture mentioned above to a monomeric helical structure, and a beta-sheet structure forms in the presence of 1 mol eq of Cu2+. As alpha-helix and beta-sheet structures are responsible for the formation of PHFs, it is hypothesized that Cu2+ is an inducer of self-assembly of the R3 peptide and makes the R3 peptide form a structure like PHF. Hence, it is postulated that Cu2+ plays an important role in the aggregation of the R3 peptide and tau protein and that copper (II) binding may be another possible involvement in AD.

Synthesis and conformational properties of phosphopeptides related to the human tau protein.

In the brains of Alzheimer's disease patients, the tau protein dissociates from the axonal microtubule and abnormally aggregates to form a paired helical filament (PHF). One of the priorities in Alzheimer research is to determine the effects of abnormal phosphorylation on the local structure. A series of peptides corresponding to isolated regions of tau protein have been successfully synthesized using Fmoc-based chemistry and their conformations were determined by 1H NMR spectroscopy and circular dichroism (CD) spectroscopy. Immunodominant peptides corresponding to tau-(256-273), tau-(350-367) and two phosphorylated derivatives in which a single Ser was phosphorylated at positions 262 and 356, respectively, were the main focus of the study. A direct alteration of the local structure after phosphorylation constitutes a new strategy through which control of biological activity can be enforced. In our study on Ser262 in R1 peptide and Ser356 in R4 peptide, phosphorylation modifies both the negative charge and the local conformation nearby the phosphorylation sites. Together, these structural changes indicate that phosphorylation may act as a conformational switch in the binding domain of tau protein to alter specificity and affinity of binding to microtubule, particularly in response to the abnormal phosphorylation events associated with Alzheimer's disease.