A sensitive fluorescence biosensor based on metal ion-mediated DNAzyme activity for amplified detection of acetylcholinesterase.

In this paper, we developed an amplified fluorescence biosensor for acetylcholinesterase (AChE) activity detection by taking advantage of the mercury ion-mediated Mgzyme (Mg2+-dependent DNAzyme) activity. The catalytic activity of Mgzyme can be inhibited by the formation of T-Hg2+-T base pairs between the Mgzyme and mercury ions. Therefore, the Mgzyme-Hg2+ complex has no activity on a molecular beacon (MB) substrate, which afforded a very weak fluorescence background for this biosensor. After the addition of acetylcholinesterase (AChE), the substrate acetylthiocholine could be hydrolyzed to thiocholine, which has a stronger binding power with mercury ions than T-Hg2+-T base pairs. Therefore, the Mgzyme activity was recovered. The activated Mgzyme could hybridize with the MB substrate and undergo many cleavage cycles, resulting in a significant increase of fluorescence intensity. This biosensor displayed high sensitivity with the detection limit as low as 0.01 mU mL-1. Moreover, this design did not require complex composition and sequence design; thus it is simple and convenient. This biosensor was also applied for the determination of AChE in human blood and showed satisfactory results.

Preserving the topological properties of complex networks in network sampling.

Extremely large-scale networks have received increasing attention in recent years. The development of big data and network science provides an unprecedented opportunity for research on these networks. However, it is difficult to perform analysis directly on numerous real networks due to their large size. A solution is to sample a subnetwork instead for detailed research. Unfortunately, the properties of the subnetworks could be substantially different from those of the original networks. In this context, a comprehensive understanding of the sampling methods would be crucial for network-based big data analysis. In our work, we find that the sampling deviation is the collective effect of both the network heterogeneity and the biases caused by the sampling methods themselves. Here, we study the widely used random node sampling (RNS), breadth-first search, and a hybrid method that falls between these two. We empirically and analytically investigate the differences in topological properties between the sampled network and the original network under these sampling methods. Empirically, the hybrid method has the advantage of preserving structural properties in most cases, which suggests that this method performs better with no additional information needed. However, not all the biases caused by sampling methods follow the same pattern. For instance, properties, such as link density, are better preserved by RNS. Finally, models are constructed to explain the biases concerning the size of giant connected components and link density analytically.

Silver-ion-mediated Mg2+-dependent DNAzyme activity for amplified fluorescence detection of cysteine.

In this paper, by taking advantage of the fact that silver ions could mediate the Mg2+-dependent DNAzyme (Mgzyme) activity, we for the first time developed a turn-on fluorescent biosensor for amplified cysteine (Cys) detection. Because Mgzyme can interact with the silver ion and form cytosine-Ag+-cytosine (C-Ag+-C) base pairs, the conformation of its catalytic core was changed. As a result, the catalytic activity of Mgzyme was suppressed and the Mgzyme-Ag+ complex could not initiate the cleavage reaction. Therefore, the background fluorescence of the biosensor was very low. In the presence of Cys, Cys can bind tightly to the silver ion and disrupt the C-Ag+-C base pairs in the Mgzyme-Ag+ complex, leading to the restoration of Mgzyme activity. The activated Mgzyme could hybridize with the MB substrate and undergo many cleavage cycles, resulting in a significant increase of fluorescence intensity. This designed strategy provided amplified fluorescence detection of cysteine, with a detection limit of 2 nM. Moreover, the strong binding between Cys and Ag+ ensured that the biosensor had a desirable selectivity for Cys. This sensing system was also used to detect Cys in human urine samples and displayed satisfying results.

Protective effect of mussel polysaccharide on cyclophosphamide-induced intestinal oxidative stress injury via Nrf2-Keap1 signaling pathway.

The hard-shelled mussel (Mytilus coruscus) has been used as a traditional Chinese medicine and health food in China for centuries. Polysaccharides from mussel has been reported to have multiple biological functions, however, it remains unclear whether mussel polysaccharide (MP) exerts protective effects in intestinal functions, and the underlying mechanisms of action remain unclear. The aim of this study was to investigate the protective effects and mechanism of MP on intestinal oxidative injury in mice. In this study, 40 male BALB/C mice were used, with 30 utilized to produce an animal model of intestinal oxidative injury with intraperitoneal injection of cyclophosphamide (Cy) for four consecutive days. The protective effects of two different doses of MP (300 and 600 mg/kg) were assessed by investigating the change in body weight, visceral index, and observing colon histomorphology. Moreover, the underlying molecular mechanisms were investigated by measuring the antioxidant enzymes and related signaling molecules through ELISA, real-time PCR, and western blot methods. The results showed that MP pretreatment effectively protected the intestinal from Cy-induced injury: improved the colon tissue morphology and villus structure, increased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities, and reduced malondialdehyde (MDA) content in serum and colon tissues. Meanwhile, MP also significantly increased the expression levels of SOD, GSH-Px, heme oxygenase-1 (HO-1), and nuclear factor E2-related factor 2 (Nrf2) mRNA in colon tissues. Further, western blot results showed that the expression of Nrf2 protein was significantly upregulated while kelch-like ECH-associated protein 1 (Keap1) was significantly downregulated by MP in the colonic tissues. This study indicates that MP can ameliorate Cy-induced oxidative stress injury in mice, and Nrf2-Keap1 signaling pathway may mediate these protective effects.

[Analysis of adverse events caused by irrational application of Houttuynia injection].

OBJECTIVE: To analyze irrational clinical application of Houttuynia Injection (HI) and the risk of adverse event (AE) occurrence, thus providing references for after-sales reevaluation and rational clinical application of HI. METHODS: Literatures concerning unreasonable application of HI were searched (terminated by June 2010) from PubMed, EMBASE, Chinese Biomedical Disc (CBMdisc), Chinese National Knowledge Infrastructure (CNKI), Chinese Science and Technology Journal Full-text Database (VIP), and etc. for case report, cross-sectional study, and clinical control study. RESULTS: A total of 342 papers with a total of 416 AE cases were retrieved. Of them, AE happened to 294 cases (including 290 children) of the 132 papers concerning contraindications, and 48 with allergic shock; AE happened to 57 cases in 9 papers reporting over-dose, and 6 with high risk combined medication. Sixteen irrational administration ways were reported in 195 papers. Of them, AE happened to 59 cases of seven administration ways (twenty cases by intracavitary injection, thirteen by aerosol inhalation, ten by rinse, eight by oral administration, one by enema, one by acupoint injection, and one by rectal administering). AE was not reported in the rest ten reports. CONCLUSION: The risk of AE occurrence was increased by changing clinical administration ways of HI without authorization, over-dose medication, high risk combined medication, and application in people with contraindications.

Brain death and organ transplant legislation: analysis of 969 respondents by classroom questionnaire.

BACKGROUND: China has the largest potential market for organ transplants in the world, but it has not yet established brain death and organ transplant laws. We aimed to investigate the attitudes and suggestions of doctors, pharmacists, and civil servants concerning brain death, organ transplantation, and their respective legislation. METHODS: A questionnaire with 10 sections and 44 questions was designed and distributed. The effective questionnaire data were then recorded and checked for descriptive analysis. RESULTS: In 1400 questionnaires distributed, 1063 were responded and 969 of them were valid and analyzed. The respondents showed an incomplete understanding of brain death and organ transplantation laws. Seventy-four percent of the respondents recognized and accepted the standard of brain death. They agreed that legislation should be involved in the removal of organs for transplantation, the future use of organs, and insurance and compensation for the donor for possible health risks induced by organ removal. Of the 969 respondents, 92% considered it necessary to have legislation in brain death and organ transplantation, and 61% thought that it is time to legislate. CONCLUSIONS: Legislation for brain death and organ transplantation is urgent and timely in China. The laws must include the respective rights and obligations of patients, close relatives, and medical institutions. Educating the public about brain death and organ transplantation should also be encouraged in a variety of ways.

Effect of Atractylodes macrocephala rhizoma on isoproterenol­induced ventricular remodeling in rats.

Myocardial infarction (MI) is the primary cause of ventricular remodeling (VR). The aim of the present study was to determine the effect of Atractylodis macrocephalae rhizoma (AMR) on VR induced by isoproterenol (ISO) in rats. Male Sprague Dawley rats were randomly divided into the normal control, ISO­induced and AMR groups. Rats in the ISO­induced and AMR groups were subcutaneously injected with 85 mg/kg/day ISO for two consecutive days. Compared with the ISO­induced group, AMR normalized the levels of hemodynamic parameters, markedly attenuated myocardial pathological damage, decreased the level of N­terminal prohormone of brain natriuretic peptide, and inhibited cardiac hypertrophy and myocardial fibrosis. In addition, AMR inhibited oxidative stress and activation of the rennin­angiotensin­aldosterone system (RAAS) when compared with the ISO­induced group. The results of the present study suggest that AMR may reverse VR via its antioxidative effect and inhibition of RAAS activation.

Effect of fermented Cordyceps sinensis on doxorubicin­induced cardiotoxicity in rats.

Cordyceps sinensis (CS) is a prominent medicinal herb in traditional Chinese medicine, and fermented CS is frequently used as a substitute for natural CS. Doxorubicin (DOX), an antitumor drug used in chemotherapy, is limited by its poor cardiotoxicity. The aim of the present study was to evaluate the protective effect of fermented CS against DOX­induced cardiotoxicity and the potential underlying mechanisms. Male Sprague­Dawley rats (180­200 g) were randomly assigned to seven different treatment groups: Normal control, DOX control, DOX+captopril (0.05 g/kg), 0.75, 1.5 and 3 g/kg DOX+CS, and the CS (1.5 g/kg) control. Histopathological changes, cardiac energy metabolism, cyclic adenosine monophosphate (cAMP) signaling and the associated mRNA expression of AMP­activated protein kinase (AMPK) were then evaluated. Fermented CS decreased the left ventricular weight index, heart weight index and mortality; however, it increased diastolic blood pressure and mean arterial pressure. In addition, it shortened the duration of the QRS complex and Sα­T segment, decreased serum creatine kinase (CK) and aspartate aminotransferase activity, inhibited histopathological changes and reduced brain natriuretic peptide content. Treatment with fermented CS also increased the activities of superoxide dismutase and glutathione peroxidase, reduced malondialdehyde content, increased the mitochondrial activities of Na+K+­adenosine 5'­triphosphate (ATP) ase, Ca2+Mg2+­ATPase and CK, and increased the creatine phosphate/ATP ratio and AMP/ATP ratio. Furthermore, it decreased the ATP/adenosine 5'­diphosphate (ADP) ratio, upregulated AMPKα2 expression, reduced the activity of serum phosphodiesterases (PDEs) and increased myocardial cAMP content. The results of the present study demonstrated that fermented CS attenuated DOX­induced cardiotoxicity by inhibiting myocardial hypertrophy and myocardial damage, ameliorating systolic function and the antioxidant enzyme system, improving cardiac energy metabolism, depressing the activities of PDEs, and by upregulating the cAMP and AMPK signaling pathways. Thus, fermented CS may be a candidate for the prevention of DOX­induced cardiotoxicity, cardiac energy impairment and against a number of cardiac diseases.

Synergistic effects of polydatin and vitamin C in inhibiting cardiotoxicity induced by doxorubicin in rats.

The purpose of this study was to assess the synergistic effect of polydatin and vitamin C on attenuating cardiotoxicity induced by doxorubicin (DOX) in rats. Polydatin could significantly increase the activity of superoxide dismutase (SOD) and the heart rate, attenuate myocardial pathological damage, decrease malondialdehyde (MDA) content, slightly increase arterial pressure and glutathione peroxidase (GSH-Px) activity, reduce intervals of QRS, QT, and ST, and lower free fatty acid (FFA) content. The combination of polydatin and vitamin C could significantly increase arterial pressure and heart rate, decrease QRS interval and slightly reduce ST and QT intervals, significantly attenuate myocardial pathological damage, increase the activities of GSH-Px,T-SOD, Na+ K+ -ATPase, and Ca2+ Mg2+ -ATPase, elevate phosphocreatine (PCr) and adenosine triphosphate (ATP) contents, slightly increase adenosine diphosphate (ADP) and total adenine nucleotide (TAN) contents and PCr/ATP, and significantly decrease the contents of MDA and FFA, when compared with those in the DOX group. Meanwhile, the improvement effects on FFA content, the activities of ATPase and SOD, and contents of ATP and TAN in combination group were more obvious than those in polydatin group, and the improvement effects on arterial pressure, heart rate, interval of QRS, GSH-Px activity, and MDA, ADP, and PCr contents in combination group were slightly obvious when compared with those in polydatin group. In addition, the mRNA expression levels of AMPK-α2 and PPAR-α were slightly improved in combination group. The results illustrate that the combination of polydatin and vitamin C has the ability to enhance the myocardial protective effects by its antioxidative effect and improve energy metabolism.

Doxorubicin toxicity changes myocardial energy metabolism in rats.

BACKGROUND: Doxorubicin (DOX) is an antitumor antibiotics used against malignancies. But its toxicity limits the therapy of DOX. OBJECTIVE: The purpose of this study was to evaluate DOX toxicity and the alteration of energy metabolism after short term and long term treatment. METHODS: Male Sprague-Dawley rats were randomly assigned to four groups: Short term control group, short term DOX treatment group, long term control group and long term DOX treatment group. In short term treated group, rats were injected with DOX i.p. at a dose of 2.5 mg/kg every 48 h for six equal injections. In long term, treated group, rats were tail-intravenously injected with DOX at a dose of 3 mg/kg once a week for four weeks. At the end of the experiment, histopathological changes, general blood biomarkers, endogenous antioxidant enzymes, cardiac energy metabolism and related mRNA expression of AMPK signal pathway were determined. RESULTS: DOX induced prominent oxidative stress, a higher mortality rate, histological and ECG changes, obvious cardiac hypertrophy, acute cardiac damage and cardiac energy impairment in short term treatment rats. In long term treatment rats, DOX caused serious nephropathy and systolic dysfunction, terrible cardiac energy impairment, clear alteration of substrate utilization and AMPK signal pathway. CONCLUSION: DOX treatment can induce different damages after short term and long term treatment. In short term treatment group, rats experienced a terrible mortality rate about 40%, the acute cardiac damage, cardiac energy impairment and an early heart failure which are potential connected with reduction of glucose utilization. In the long term treatment group, serious nephropathy and obvious changes of mRNA expressions of AMPK signal pathway were observed. Meanwhile, the serious cardiac energy impairment and substrate utilization alteration denote an obviously heart failure. This study could be helpful to develop therapy strategies of DOX complications for clinical application.

Effects of fermented Cordyceps sinensis on oxidative stress in doxorubicin treated rats.

BACKGROUND: Cordyceps sinensis (CS) is one of the rare traditional Chinese herbs, only a very limited amount of natural CS is produced. Fermented CS, as a substitute for natural CS, is widely used in the field of supplementary medical treatment and health products. Its antagonistic effect on oxidative stress (OS) in vivo has not been investigated. OBJECTIVE: Our aim was to investigate the antagonistic effect of fermented CS on OS in doxorubicin (DOX) treated rats and to compare the anti-OS effects in heart and liver tissues. MATERIALS AND METHODS: OS rats were induced by tail-intravenous injection of DOX (total of 7.5 mg/kg), and then administered intragastrically with fermented CS (1.5 g/kg) for 4 weeks. At the end of the experiment, heart, liver and serum samples were taken for and biochemical analyses. RESULTS: Fermented CS significantly increased the activities of glutathione peroxidase and catalase and the scavenging activity of O2 (-) in serum, and the total superoxide dismutase activity in cardiac tissue; reduced the malondialdehyde content in liver and cardiac tissues. CONCLUSION: Fermented CS can inhibit DOX-induced OS reactions, and the anti-OS effects have high selectivity to heart and liver, especially to heart. Thus, fermented CS may be a candidate used for the prevention against various cardiac diseases induced by OS.

Comparative studies of polydatin and resveratrol on mutual transformation and antioxidative effect in vivo.

BACKGROUND: Polydatin and resveratrol are extractives of radix or rhizoma of Polygonum cuspidatum, and as the glycoside forms, it is a natural precursor of resveratrol. PURPOSE: In this study, we aimed to explore the mutual transformation between polydatin and resveratrol in rats, and to compare the antioxidative effect of them in vivo. STUDY DESIGN: In this study, we analyzed the serum molar concentration of polydatin and resveratrol after oral administration in rats and evaluated the anti-oxidative stress effects of them using a mouse model. METHODS: Rats were orally administered polydatin or resveratrol and the concentration of them in serum were analyzed by high performance liquid chromatography (HPLC). Their antioxidative effect was compared in mice with oxidative stress cardiomyopathy induced by doxorubicin (DOX). RESULTS: The results showed that polydatin and resveratrol could mutually transform in vivo, the molar concentration of polydatin in serum was always averagely 3.35 and 4.28 times as much as resveratrol after oral administration of polydatin and resveratrol at 200 mg/kg, respectively. Both polydatin and resveratrol could significantly decrease the content of malonydialdehyde (MDA), promote the activities of total superoxide dismutase (T-SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in plasma, and increase the content of glutathione (GSH) in myocardial tissue. The effect of polydatin surpassed resveratrol, particularly embodied in increasing the activities of T-SOD and CAT, and the content of GSH. CONCLUSION: It illustrates that polydatin is the main substance in serum after intragastric administration with polydatin or resveratrol, and the mutual transformation between polydatin and resveratrol keeps balance; they both have the ability of antioxidative stress in vivo, and polydatin has a better effect than resveratrol, which hints that polydatin may be a substitute for resveratrol in antioxidant for clinical use.

Mycobacterium vaccae vaccine to prevent tuberculosis in high risk people: a meta-analysis.

OBJECTIVE: To evaluate the effectiveness and safety of Mycobacterium vaccae (MV) in prevention of tuberculosis (TB) among high risk people. METHODS: Database of MEDLINE, EMBASE, BIOSIS, SCI, Cochrane Central Register of Controlled Trials, CBM, CNKI and VIP were searched till July 2009. Randomized controlled trials (RCTs) or non-randomized controlled clinical trials (CCTs) investigating MV as interventions in people at high risk of TB were identified for critical appraisal. Two reviewers independently performed data extraction and quality assessment. Effectiveness of MV was summarized in different group of risk people through RevMan 5.0 by The Cochrane Collaboration. RESULTS: Thirteen studies were included. Risk difference (RD) of protection index (PI), its 95% confidence interval (95%CI) and the P value were as following: MV vs. Isoniazid (INH): 0.02 (-0.01, 0.05) (P=0.12); MV vs. (INH plus RFT): 0.00 (-0.00, 0.00) (P=1.00); MV vs. Blank: 0.04 (0.00, 0.08) (P=0.03) for soldiers with PPD strong positive; 0.00 (-0.00, 0.00) (P=0.05) for students with PPD strong positive; 0.20 (0.05, 0.36) (P=0.01) for aged people of clinical cured pulmonary TB, and 0.08 (0.01, 0.14) (P=0.03) for type 2 diabetes mellitus. In HIV-infected people, The Risk Ratio (RR) of MV vs. CV (control vaccine) of positive stimulation index (SI) (> or = 3) in lymphocyte proliferation assays (LPA) to Mycobacterium vaccae sonicate (MVS) was 2.39 with 95% CI (1.56, 3.66), P<0.0001. Immunization had no adverse effects on CD4 cell count or HIV viral load. The most frequent adverse effects of MV were induration and sore arm. CONCLUSIONS: Available evidence shows that MV is effective in preventing TB in PPD strong positive/type 2 diabetes mellitus/aged people of clinical cured pulmonary TB, and is safe, well-tolerated and effective in inducing biologically relevant immune response against TB in HIV-infected patients. High-quality trials aimed at different groups of high risk people are encouraged.