Vascular Aging and Atherosclerosis: A Perspective on Aging

Vascular aging (VA) is recognized as a pivotal factor in the development and progression of atherosclerosis (AS). Although various epidemiological and clinical research has demonstrated an intimate connection between aging and AS, the candidate mechanisms still require thorough examination. This review adopts an aging-centric perspective to deepen the comprehension of the intricate relationship between biological aging, vascular cell senescence, and AS. Various aging-related physiological factors influence the physical system's reactions, including oxygen radicals, inflammation, lipids, angiotensin II, mechanical forces, glucose levels, and insulin resistance. These factors cause endothelial dysfunction, barrier damage, sclerosis, and inflammation for VA and promote AS via distinct or shared pathways. Furthermore, the increase of senescent cells inside the vascular tissues, caused by genetic damage, dysregulation, secretome changes, and epigenetic modifications, might be the primary cause of VA.

Sheng Mai Yin shows anti-fatigue, anti-hypoxia and cardioprotective potential in an experimental joint model of fatigue and acute myocardial infarction

ETHNOPHARMACOLOGICAL RELEVANCE

Cardiovascular disease (CVD) and fatigue are two common diseases endangering human life and health that may interact and reinforce one another. Myocardial infarction survivors frequently experience fatigue, and acute myocardial infarction (AMI) is one of the most common cardiovascular diseases that cause fatigue-induced sudden death. Sheng Mai Yin (SMY), a Chinese medicine prescription, is traditionally used for the treatment of diabetes and cardiovascular disease, and has been demonstrated to reduce fatigue and safeguard cardiac function.

AIM OF THE STUDY

This study aims to investigate the effects and underlying mechanisms of SMY in treating fatigue and AMI.

MATERIALS AND METHODS

The pharmacological mechanisms of SMY in treating fatigue and AMI were predicted by bioinformatics and network pharmacology methods. After administering SMY at high, medium and low doses, the swimming time to exhaustion, hemoglobin level, serological parameters and hypoxia tolerance time were detected in C57BL/6N mice, and the left ventricular ejection fractions (LVEF), left ventricular fractional shortening (LVFS), grasp strength, cardiac histopathology, serological parameters and the expression of PINK1 and Parkin proteins were examined in Wistar rats.

RESULTS

371 core targets for SMY and 282 disease targets for fatigue and AMI were obtained using bioinformatics and network pharmacology methods. Enrichment analysis of target genes revealed that SMY might interfere with fatigue and AMI through biological processes such as mitochondrial autophagy, apoptosis, and oxidative stress. For in vivo experiments, SMY showed significant anti-fatigue and hypoxia tolerance effects in mice; It also improved the cardiac function and grasp strength, decreased their cardiac index, myocardial injury and fibrosis degree, and induced serological parameters levels and the expression of PTEN-induced putative kinase 1 (PINK1) and Parkin proteins in myocardium, suggesting that SMY may exert cardioprotective effects in a joint rat model of fatigue and AMI by inhibiting excessive mitochondrial autophagy.

CONCLUSION

This study revealed the anti-fatigue, anti-hypoxia and cardioprotective effects of SMY in a joint model of fatigue-AMI, and the pharmacological mechanism may be related to the inhibition of mitochondrial autophagy in cardiomyocytes through the PINK1/Parkin pathway. The discoveries may provide new ideas for the mechanism study of traditional Chinese medicine, especially complex prescriptions, in treating fatigue and AMI.

Antiviral effect and mechanism of Phillyrin and its reformulated FS21 against influenza

Background

Influenza virus causes significant morbidity and mortality with pandemic threat. Oleaceae Fructus Forsythiae is a medicinal herb. This study aimed to investigate antiviral effect of Phillyrin, a purified bioactive compound from this herb, and its reformulated preparation FS21 against influenza and its mechanism.

Methods

Madin-Darby Canine Kidney (MDCK) cells were infected by one of six influenza viruses: five influenza A viruses (IAVs: three H1N1 and two H3N2) and one influenza B virus (IBV). Virus-induced cytopathic effects were observed and recorded under microscope. Viral replication and mRNA transcription were evaluated by quantitative polymerase chain reaction (qPCR) and protein expression by Western blot. Infectious virus production was assessed using TCID50 assay, and IC50 was calculated accordingly. Pretreatment and time-of-addition experiments with Phillyrin or FS21 added 1 h before or in early (0-3 h), mid (3-6 h), or late (6-9 h) stages of viral infection were performed to assess their antiviral effects. Mechanistic studies included hemagglutination and neuraminidase inhibition, viral binding and entry, endosomal acidification, and plasmid-based influenza RNA polymerase activity.

Results

Phillyrin and FS21 had potent antiviral effects against all six IAV and IBV in a dose-dependent manner. Mechanistic studies showed that both suppressed influenza viral RNA polymerase with no effect on virus-mediated hemagglutination inhibition, viral binding or entry, endosomal acidification, or neuraminidase activity.

Conclusions

Phillyrin and FS21 have broad and potent antiviral effects against influenza viruses with inhibition of viral RNA polymerase as the distinct antiviral mechanism.

Effects of Tai Chi on health status in adults with chronic heart failure: A systematic review and meta-analysis

Background

Chronic heart failure (CHF) is among the top causes of cardiovascular morbidity, and most patients with CHF have poor health status. Tai Chi, a mind-body exercise that originated in China, is beneficial for health status. This study was conducted to evaluate the effects of Tai Chi on health status in adults with CHF.

Methods

The Cochrane Library, PubMed, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang Database, Chinese Biomedical Database, and Chinese Scientific Journal Database were searched from the inception to 22 October 2021. This meta-analysis was performed using the fixed- or random-effects model. Continuous outcomes were carried out using mean difference (MD) or standardized mean difference (SMD) with 95% confidence interval (CI). Dichotomous outcomes were determined using risk ratio (RR) with 95%CI. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE)pro Guideline Development Tool (GDT) online software was used to present outcome-specific information regarding overall certainty of evidence from studies.

Results

In total, 15 studies including 1,236 participants were finally included. Compared with usual care alone, Tai Chi combined with usual care achieved efficacy in improving Minnesota Living with Heart Failure Questionnaire (MD = -8.51; 95% CI: -10.32 to -6.70; p < 0.00001), 6-min walk test (MD = 43.47; 95% CI: 33.38 to 54.10; p < 0.00001), left ventricular ejection fraction (MD = 6.07; 95% CI: 3.44 to 8.70; p < 0.00001), B-type natriuretic peptide/N-terminal fragment of pro-BNP (SMD = -1.12; 95% CI: -1.70 to -0.54; p = 0.0002), Hamilton Depression Rating Scale (MD = -2.89; 95% CI: -4.87 to -0.91; p = 0.004), Pittsburgh Sleep Quality Index (MD = -2.25; 95% CI: -3.88 to -0.61; p = 0.007), timed up and go test (MD = -1.34; 95% CI: -2.50 to -0.19; p = 0.02), and reduced the risk of heart failure hospitalization (RR = 0.47; 95% CI: 0.25 to 0.88; p = 0.02). However, there was no difference in the outcome of peak oxygen uptake (MD = 1.38; 95% CI: -1.51 to 4.28; p = 0.35). All-cause mortality or cardiovascular death could not be evaluated due to insufficient data. The certainty of evidence ranged from very low to moderate due to the risk of bias, inconsistency, imprecision, and publication bias.

Conclusion

Tai Chi might be safe and showed beneficial effects on health status in patients with CHF. However, more high-quality and long-term studies are still needed to further evaluate the effects of Tai Chi.

A Bibliometric Analysis of Research on the Links Between Gut Microbiota and Atherosclerosis

Background

Emerging evidence has linked gut microbiota (GM) and its related metabolites to atherosclerosis (AS). This study aimed to analyze the evolution of GM in AS in the past decades, and provide valuable insights in this field.

Methods

Web of Science Core Collection (WoSCC) was applied to retrieve the publications related to GM in AS from their inception until 2 December 2021, and the data was analyzed in Microsoft Excel, Scimago Graphica, CiteSpace, and VOSviewer.

Results

In total, 560 documents were extracted from the WoSCC databases. The publications have shown rapid growth since 2008. China and Cleveland Clin were the most prolific country and institution, respectively. The journal with the most publications is Nutrients, and Nature was the most co-cited journal. Among 3556 related authors, Hazen, Stanley L., Tang, W. H. Wilson, and Wang, Zeneng were the top 3 contributing authors in this field. Aside from “gut microbiota,” “atherosclerosis,” the terms “TMAO,” “metabolite,” “obesity,” and “phosphatidylcholine” were frequently occurred in the abstract and title of articles. Burst detection of keywords indicated that “metabolic syndrome,” “acid,” and “bile acid” were hot topics in recent years. According to the co-citation analysis of references, the research focus in this area has changed over time, and recent researches focus on choline, hypertension, butyrate, and berberine.

Conclusion

Our study showed that the researches of GM in AS have been flourishing, and the content themes were constantly deepened. Human GM is critical to atherosclerotic diseases, and this hot topic is still worthy of more focus in the future.

Pantao Pill Improves the Learning and Memory Abilities of APP/PS1 Mice by Multiple Mechanisms

Background: To explore the effect and mechanisms of Pantao Pill (PTP) on cognitive impairment.

Methods: Network pharmacology was performed to analyze the mechanism of PTP treating cognitive impairment. The targets of PTP and cognitive impairment were predicted and used to construct protein-protein interaction (PPI) networks. The intersection network was selected, and the core network was obtained through topological analysis. Enrichment analysis was conducted to obtain the GOBP terms and KEGG pathways. We then performed experiments to validate the results of the network pharmacology by using an APP/PS1 transgenic mouse model. The APP/PS1 mice were divided into four groups: the model group, the high-dose PTP (3.6 g/kg·d) group, the low-dose PTP (1.8 g/kg·d) group, and the positive control group (donepezil hydrochloride, 2 mg/kg·d). Wild-type (WT) C57 mice served as a normal control group. PTP and donepezil were administered by gavage for 8 weeks.

Results: Network pharmacology showed that PTP might improve cognitive impairment by regulating autophagy, apoptosis, and oxidative stress. For the Morris water maze test, a significant difference was shown in the total swimming distance among groups (p < 0.05) in the positioning navigation experiment, and with training time extension, the swimming speed increased (p < 0.01). In the space probe test, PTP administration significantly reduced the swimming path length and the escape latency of APP/PS1 mice (p < 0.05 or p < 0.01), whereas it had no effect on the swimming speed (p > 0.05). PTP (3.6 g/kg/d) rescued the reduction of norepinephrine and acetylcholine levels (p < 0.05), and increased the acetylcholinesterase concentration (p < 0.05) in the brain tissue. PTP (1.8 g/kg/d) increased the norepinephrine level (p < 0.01). PTP rescued the activity reduction of superoxide dismutase in the brain tissue (p < 0.01) and the neuron cell pyknosis in the hippocampal CA region (p < 0.05). PTP reduced ATG12 and PS1 expression (p < 0.05 or p < 0.01), and increased Bcl-2 expression in the brain tissue (p < 0.05).

Conclusion: PTP can significantly improve the learning and memory abilities of APP/PS1 mice, and the mechanism may be related to the increase of neurotransmitter acetylcholine and norepinephrine levels, the reduction of the excessive autophagic activation, and the suppression of oxidative stress and excessive apoptotic activity.

Red Yeast Rice Preparations Reduce Mortality, Major Cardiovascular Adverse Events, and Risk Factors for Metabolic Syndrome: A Systematic Review and Meta-analysis

Background: Metabolic syndrome (MetS) is characterized by the cooccurrence of obesity, insulin resistance, dyslipidaemia, and hypertension. Red yeast rice (RYR) preparations might be beneficial for the prevention and treatment of MetS. Objective: To implement a systematic review and meta-analysis to determine whether RYR preparations improve clinical endpoints and reduce risk factors for MetS. Methods: The PubMed, Cochrane Library, EMBASE, Scopus, China National Knowledge Infrastructure, Chinese VIP Information, and WanFang databases were searched for randomized controlled trials (published up to September 2020), and a meta-analysis was performed using fixed- or random-effects models. The primary outcome measures were mortality and major adverse cardiovascular events (MACEs), and the secondary outcome measures were biochemical parameters of blood glucose, blood lipids, and blood pressure. The registration number is CRD42020209186. Results: A total of 921 articles were identified, of which 30 articles were included in this article. RYR preparations group demonstrated significant improvements in MetS compared with control group. RYR preparations reduced the mortality and MACEs (RR = 0.62, 95% CI [0.49, 0.78]; RR = 0.54, 95% CI [0.43, 0.66]). In terms of blood glucose metabolism, fasting plasma glucose (FPG) (MD = -0.46 mmol/L, 95% CI [-0.71, -0.22]), haemoglobin A1c (HbA1c) (MD = -0.49, 95% CI [-0.71, -0.26]) and the homeostasis model assessment of insulin resistance (HOMA-IR) (MD = -0.93, 95% CI [-1.64, -0.21]) were decreased. Regarding the lipid metabolism, total cholesterol (TC) (MD = -0.74 mmol/L, 95% CI [-1.02, -0.46]), triglycerides (TG) (MD = -0.45 mmol/L, 95% CI [-0.70, -0.21]), and low-density lipoprotein cholesterol (LDL) (MD = -0.42 mmol/L, 95% CI [-0.78, -0.06]) were decreased, while high-density lipoprotein cholesterol (HDL) (MD = 0.14 mmol/L, 95% CI [0.09, 0.20]) was increased. Regarding blood pressure, the mean arterial pressure (MAP) (MD = -3.79 mmHg, 95% CI [-5.01, -2.57]) was decreased. In addition, RYR preparations did not increase the incidence of adverse reactions (RR = 1.00, 95% CI [0.69, 1.43]). Conclusion: RYR preparations reduce mortality, MACEs, and multiple risk factors for MetS without compromising safety, which supports its application for the prevention and treatment of MetS. However, additional high-quality studies are needed to provide more evidence for the effect of RYR on MetS due to the heterogeneity in this study. Systematic Review Registration: www.crd.york.ac.uk/PROSPERO, identifier CRD42020209186.

Oxyphylla A ameliorates cognitive deficits and alleviates neuropathology via the Akt-GSK3β and Nrf2-Keap1-HO-1 pathways in vitro and in vivo murine models of Alzheimer's disease

Introduction

Alzheimer’s disease (AD) is a progressive brain disorder, and one of the most common causes of dementia and amnesia. Due to the complex pathogenesis of AD, the underlying mechanisms remain unclear. Although scientists have made increasing efforts to develop drugs for AD, no effective therapeutic agents have been found.

Objectives

Natural products and their constituents have shown promise for treating neurodegenerative diseases, including AD. Thus, in-depth study of medical plants, and the main active ingredients thereof against AD, is necessary to devise therapeutic agents.

Methods

In this study, N2a/APP cells and SAMP8 mice were employed as in vitro and in vivo models of AD. Multiple molecular biological methods were used to investigate the potential therapeutic actions of oxyphylla A, and the underlying mechanisms.

Results

Results showed that oxyphylla A, a novel compound extracted from Alpinia oxyphylla, could reduce the expression levels of amyloid precursor protein (APP) and amyloid beta (Aβ) proteins, and attenuate cognitive decline in SAMP8 mice. Further investigation of the underlying mechanisms showed that oxyphylla A exerted an antioxidative effect through the Akt-GSK3β and Nrf2-Keap1-HO-1 pathways.

Conclusions.

Taken together, our results suggest a new horizon for the discovery of therapeutic agents for AD.

Amelioration of AOM/DSS-Induced Murine Colitis-Associated Cancer by Evodiamine Intervention is Primarily Associated with Gut Microbiota-Metabolism-Inflammatory Signaling Axis

Evodiamine (EVO), an indole alkaloid derived from Rutaceae plants Evodia rutaecarpa (Juss.) Benth.、Evodia rutaecarpa (Juss.) Benth. Var. bodinieri (Dode) Huang or Evodia rutaecarpa (Juss.) Benth. Var. officinalis (Dode) Huang, has anti-inflammatory and anti-tumor activities. Our previous study found that EVO attenuates colitis by regulating gut microbiota and metabolites. However, little is known about its effect on colitis-associated cancer (CAC). In this study, the protective effects of EVO on azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis and tumor mice were observed, and the underlying potential mechanism was clarified. The results suggested that EVO ameliorated AOM/DSS-induced colitis by inhibiting the intestinal inflammation and improving mucosal barrier function. And EVO significantly reduced the number and size of AOM/DSS-induced colorectal tumors along with promoted apoptosis and inhibited proliferation of epithelial cell. Moreover, EVO promoted the enrichment of SCFAs-producing bacteria and reduced the levels of the pro-inflammatory bacteria, which contributes to the changes of microbiota metabolism, especially tryptophan metabolism. Furthermore, inflammatory response (like Wnt signaling pathway、Hippo signaling pathway and IL-17 signaling pathway) were effectively alleviated by EVO. Our study demonstrated that the protective therapeutic action of EVO on CAC is to inhibit the development of intestinal inflammation-cancer by regulating gut microbiota metabolites and signaling pathways of colon intestinal epithelial, which may represent a novel agent for colon cancer prevention via manipulation of gut microbiota.

Efficacy and Safety of Tongxinluo Capsule as Adjunctive Treatment for Unstable Angina Pectoris: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Tongxinluo capsule (TXLC) is a commonly used Chinese medicine for unstable angina pectoris (UA). This article aimed to clarify the safety and efficacy of TXLC as an adjunctive treatment for UA. Two reviewers searched 7 databases from inception to August 2021, and performed literature screening and information extraction independently. The meta-analysis was implemented after evaluating the methodological quality of each randomized controlled trial (RCT) by the Cochrane Risk of Bias tool. Sensitivity analyses were conducted for testing the stability of the results, and the Begg and Egger tests were performed for any potential publication bias. After eligibility assessment, 42 RCTs with a total of 5,421 participants were included. Evidence showed that TXLC reduced the rate of cardiovascular events [RR = 0.29, 95% CI (0.19, 0.45), p < 0.00001, I ² = 0%] {including cardiovascular mortality [RR = 0.16, 95% CI (0.03, 0.88), p = 0.03, I ² = 20%], the incidence of acute myocardial infarction [RR = 0.27, 95% CI (0.13, 0.57), p = 0.0006, I ² = 0%] and the occurrence of revascularization [RR = 0.28, 95% CI (0.15,0.54), p = 0.0001, I ² = 0%]}, all-cause mortality [RR = 0.25, 95% CI (0.06, 0.99), p = 0.05, I ² = 19%], recurrence of angina [RR = 0.25, 95% CI (0.11, 0.61), p = 0.002, I ² = 0%], the number of ST-segment depression [MD = -0.45, 95% CI (-0.69, -0.20), p = 0.0005, I ² = 0%], the summation of ST-segment depression [MD = -0.70, 95% CI (-1.08, -0.32), p = 0.0003, I ² = 70%] and the hypersensitive C-reactive protein level [MD = -2.86, 95% CI (-3.73, -1.99), p < 0.00001, I ² = 86%], increased the nitric oxide level [MD = 11.67, 95% CI (8.33, 15.02), p < 0.00001, I ² = 33%], improved the electrocardiogram change [RR = 1.23, 95% CI (1.16, 1.30), p < 0.00001, I ² = 0%] and the clinical efficacy in UA [RR = 1.26, 95% CI (1.21, 1.32), p < 0.00001, I ² = 24%], and relieved the symptoms of angina pectoris {including chest pain or tightness [RR = 1.13, 95% CI (0.97, 1.32), p = 0.12, I ² = 30%], palpitations [RR = 1.47, 95% CI (1.18, 1.84), p = 0.0007, I ² = 0%], shortness of breath [RR = 1.53, 95% CI (1.24, 1.88), p < 0.0001, I ² = 0%], and asthenia [RR = 1.69, 95% CI (0.83, 3.43), p = 0.15, I ² = 90%]}. The most common adverse effect was gastrointestinal symptoms which could be relieved and eliminated through dose reduction, medication time adjustment and symptomatic remedy. Collectively, TXLC was effective and considerably safe for UA. However, due to the unavoidable risk of bias, these results must be interpreted with caution and further verified by large-scale and high-quality RCTs. Systematic Review Registration: www.crd.york.ac.uk/PROSPERO/, identifier CRD42021232771.

A New Therapeutic Candidate for Cardiovascular Diseases: Berberine

Cardiovascular diseases (CVD) are the leading cause of death in the world. However, due to the limited effectiveness and potential adverse effects of current treatments, the long-term prognosis of CVD patients is still discouraging. In recent years, several studies have found that berberine (BBR) has broad application prospects in the prevention and treatment of CVD. Due to its effectiveness and safety for gastroenteritis and diarrhea caused by bacterial infections, BBR has been widely used in China and other Asian countries since the middle of the last century. The development of pharmacology also provides evidence for the multi-targets of BBR in treating CVD. Researches on CVD, such as arrhythmia, atherosclerosis, dyslipidemia, hypertension, ischemic heart disease, myocarditis and cardiomyopathy, heart failure, etc., revealed the cardiovascular protective mechanisms of BBR. This review systematically summarizes the pharmacological research progress of BBR in the treatment of CVD in recent years, confirming that BBR is a promising therapeutic option for CVD.

Neovascularization: The Main Mechanism of MSCs in Ischemic Heart Disease Therapy

Mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been shown to effectively limit the infarct area in numerous clinical and preclinical studies. However, the primary mechanism associated with this activity in MSC transplantation therapy remains unclear. Blood supply is fundamental for the survival of myocardial tissue, and the formation of an efficient vascular network is a prerequisite for blood flow. The paracrine function of MSCs, which is throughout the neovascularization process, including MSC mobilization, migration, homing, adhesion and retention, regulates angiogenesis and vasculogenesis through existing endothelial cells (ECs) and endothelial progenitor cells (EPCs). Additionally, MSCs have the ability to differentiate into multiple cell lineages and can be mobilized and migrate to ischemic tissue to differentiate into ECs, pericytes and smooth muscle cells in some degree, which are necessary components of blood vessels. These characteristics of MSCs support the view that these cells improve ischemic myocardium through angiogenesis and vasculogenesis. In this review, the results of recent clinical and preclinical studies are discussed to illustrate the processes and mechanisms of neovascularization in ischemic heart disease.

Design, synthesis and evaluation of a baicalin and berberine hybrid compound as therapeutic agent for ulcerative colitis

Structural modification of active natural compoundswhichwereoriginated fromTraditional Chinese Medicine (TCM) have showedgreat advantagesin thedevelopmentof new drugs. In TCM, "Huangqin-Huanglian" is a classic "medicine couple"thathas been used to treat intestinal diseases for thousands ofyears, while baicalinand berberine are the major active compoundsof Huangqin and Huanglianrespectively. Based onthis"medicine couple",wedesignedand synthesizeda newbaicalin and berberine hybrid compound (BBH).Its molecular structure wasconfirmedby spectroscopy.The antibacterial activity of BBH was detected in vitro.Results indicatedthat the new hybrid compound exhibited the best antibacterial activity forproteobacteria as compared with its original synthetic materials (baicalin andberberine). In vivo, the effect of BBHon ulcerative colitiswas alsoinvestigated.BBH treatment significantly ameliorated the disease symptoms andpreventedthe colon damage of ulcerative colitis. Furthermore, BBH showed asignificant anti-inflammatory effect through regulating activities of SOD, MPOandexpressions of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in colontissue. Data also suggested that BBH was more superior than baicalin and berberine inameliorating colonic damage. This indicated that the new hybrid compound BBHshowed enhanced efficacy in treating ulcerative colitis.

A randomised phase II trial of hydroxychloroquine and imatinib versus imatinib alone for patients with chronic myeloid leukaemia in major cytogenetic response with residual disease

In chronic-phase chronic myeloid leukaemia (CP-CML), residual BCR-ABL1+ leukaemia stem cells are responsible for disease persistence despite TKI. Based on in vitro data, CHOICES (CHlorOquine and Imatinib Combination to Eliminate Stem cells) was an international, randomised phase II trial designed to study the safety and efficacy of imatinib (IM) and hydroxychloroquine (HCQ) compared with IM alone in CP-CML patients in major cytogenetic remission with residual disease detectable by qPCR. Sixty-two patients were randomly assigned to either arm. Treatment 'successes' was the primary end point, defined as ≥0.5 log reduction in 12-month qPCR level from trial entry. Selected secondary study end points were 24-month treatment 'successes', molecular response and progression at 12 and 24 months, comparison of IM levels, and achievement of blood HCQ levels >2000 ng/ml. At 12 months, there was no difference in 'success' rate (p = 0.58); MMR was achieved in 80% (IM) vs 92% (IM/HCQ) (p = 0.21). At 24 months, the 'success' rate was 20.8% higher with IM/HCQ (p = 0.059). No patients progressed. Seventeen serious adverse events, including four serious adverse reactions, were reported; diarrhoea occurred more frequently with combination. IM/HCQ is tolerable in CP-CML, with modest improvement in qPCR levels at 12 and 24 months, suggesting autophagy inhibition maybe of clinical value in CP-CML.

A review for the anti-inflammatory effects of paeoniflorin in inflammatory disorders

Inflammatory disorders result from abnormal immune response and their incidence has increased recently. Thus, there is an urgent need to discover new treatments for inflammatory disorders. In recent years, the natural products contained in Chinese herbs have attracted much attention worldwide owing to their anti-inflammatory effects. Paeoniflorin (PF) is a bioactive compound purified from the Chinese herb Paeonia lactiflora and reports have recently emerged suggesting the great potential of P. lactiflora as an agent to counter inflammatory disorders. The anti-inflammatory effects of PF have been revealed by in vitro studies and in vivo animal experiments of different inflammatory disorders, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, and asthma. This review systematically describes the recent progress of studies on the mechanism of PF and its therapeutic potential in inflammatory disorders.

A combined molecular biology and network pharmacology approach to investigate the multi-target mechanisms of Chaihu Shugan San on Alzheimer's disease

Chaihu Shugan San (CSS) is a well-known herbal formula used to nourish liver and blood, promote blood circulation and Qi flow in Traditional Chinese Medicine. Modern pharmacological studies and clinical uses showed that CSS could ameliorate cognitive dysfunction of Alzheimer's disease (AD). The present study aimed to elucidate the multi-target mechanisms of CSS on AD using network pharmacology analysis and verify its effect by biological experiments. Firstly, a total of 152 active compounds in CSS, 520 predicted biological targets and 160 AD-related targets were identified. Subsequently, the networks including herb-compound-target network, AD-target network, and CSS potential target-AD target network were constructed. 60 key targets highly responsible for the beneficial effect of CSS on AD were identified by central network topological analysis. They were significantly characterized as nuclear or cytoplasmic proteins with molecular function of protein binding. They were also enriched in various biological processes through PI3K-Akt signaling pathway, MAPK signaling pathway and HIF signaling pathway by GO function and KEGG pathway enrichment analysis. Pretreatment with CSS ameliorated Aβ-induced neural cell death and reduced the number of apoptotic cells in differentiated PC12 cells. Moreover, increased phosphorylation of Akt accompanied with decreased Bax expression was found after CSS pretreatment, suggesting that Akt signaling pathway was involved in the protective effect of CSS against neural cells death. The present study systematically revealed the multi-target mechanisms of CSS on AD using network pharmacology approach, as well as validated the protective effect of CSS against Aβ-induced neural cells death through Akt signaling pathway. It provided indications for further mechanistic studies and also for the development of CSS as a potential treatment for AD patients.

Chinese Medicines Improve Perimenopausal Symptoms Induced by Surgery, Chemoradiotherapy, or Endocrine Treatment for Breast Cancer

The application of surgery, chemoradiotherapy, and endocrine treatment successfully increases survival rates of breast cancer patients. However, perimenopausal symptoms, the main side effects of these treatments, often afflict patients and reduce their quality of life. Perimenopausal symptoms include vasomotor symptoms, sleep problems, arthromuscular symptoms, and osteoporosis. Currently, there are no satisfactory treatments for perimenopausal symptoms that result from these treatments. Therefore, alternative and complementary therapies including herbal medicines represented by Chinese medicines (CMs), acupuncture, massage, and psychotherapy are increasingly being expected and explored. In this paper, we review the effects and potentials of several CM formulae, along with some active ingredients or fractions from CMs, Chinese herbal extracts, and other herbal medicines, which have drawn attention for improving perimenopausal symptoms in breast cancer patients. We also elaborate their possible mechanisms. Moreover, further studies for evaluation of standardized clinical efficacy should be scientifically well-designed and continuously performed to investigate the efficacy and mechanisms of CMs for perimenopausal symptoms due to breast cancer therapy. The safety and value of estrogen-containing CMs for breast cancer should also be clarified.

Puerarin Reduces Blood Pressure in Spontaneously Hypertensive Rats by Targeting eNOS

Puerarin is an isoflavonoid isolated from the root of Pueraria lobata (Gegen in Chinese) that has been widely used to treat cardiovascular and cerebrovascular diseases in China. Here, we investigated the hypotensive effects and mechanisms of puerarin in spontaneously hypertensive rats. The qPCR array technique was used to determine the expression of hypertension-related genes. Then, the differentially expressed genes were analyzed using the STRING database. The systolic blood pressure and diastolic blood pressure of rats decreased after the administration of puerarin for nine weeks. Puerarin, but not losartan, also slowed the heart rate of rats. NO and cGMP levels were improved by puerarin. Eighteen differentially expressed hypertension-related genes were identified by comparing the model group with the control group and the high-dose puerarin group with the model group. NO and cGMP levels were increased by high-dose puerarin. High-dose puerarin increased the levels of the phosphorylated eNOS protein and decreased AT1 and Cav1 levels. Based on our results, eNOS was a key target in the mechanism by which puerarin reduced blood pressure, and puerarin represents a potential antihypertensive agent.

Chinese Herbal Medicines Facilitate the Control of Chemotherapy-Induced Side Effects in Colorectal Cancer: Progress and Perspective

Side effects, including nausea, vomiting, mucositis, peripheral neuropathy, and diarrhea, have been frequently reported in colorectal cancer (CRC) patients undergoing chemotherapy. Chinese Herbal Medicines (CHMs) display distinct clinical outcomes, as a result, they have been increasingly used as an adjuvant therapy to manage chemotherapy-induced side effects. In this review, we aim to intensively explore the molecular mechanisms of CHMs, underline the significance of CHMs in mitigating the side effects induced by chemotherapy, and examine the necessary studies required to understand the role of CHMs in alleviating chemotherapy-induced side effects. Specifically, ginger, Astragali Radix, and Liujunzi Decoction have been verified to ameliorate nausea and vomiting. Banxia Xiexin Decoction and Huangqin Decoction have been confirmed to be beneficial to mucositis and delayed-onset of diarrhea. Moreover, Niuche Shenqi Wan, Guilong Tongluo Decoction, Huangqi Guizhi Wuwu Decoction, and tumeric have been found to display potential therapeutic effects for preventing the genesis and development of peripheral neurotoxicity. These findings have further emphasized the pivotal role of CHMs in improving the outcomes of chemotherapy-induced side effects in CRC. Nonetheless, more molecular evidence is required to comprehensively understand and more appropriately apply CHMs in routine clinical practice for CRC.

[Clinical observation of fast acupuncture for cervical type of cervical spondylosis]

OBJECTIVE

To compare the effects between fast acupuncture and retaining acupuncture for the cervical type of cervical spondylosis.

METHODS

Sixty patients were randomized into a fast acupuncture group and a retaining needle group, 30 cases in each one. The acupoints in the two groups were Fengchi (GB 20), Jiaji (EX-B 2, C₂, C₄, C₆) and Jianjing (GB 21), Jianjing 1 (Extra) and Jianjing 2 (Extra). The needles in the fast acupuncture group were out after qi arrival, while those in the retaining needle group were retained for 30 min, three times a week, once the other day. One week was seen as a course and the treatment was given for 2 courses. The indices were observed before and after treatment, including Northwick Park neck pain questionnaire (NPQ), short-form McGill pain questionnaire (SF-MPQ) [pain rating index (PRI), visual analogue scale (VAS) and present pain intensity (PPI)]. The effects were compared in the two groups.

RESULTS

After treatment, the NPQ score was lower than that before treatment in the two groups (both P<0.01), and that in the fast acupuncture group was better (P<0.01). All the items of SF-MPQ decreased compared with those before treatment in the two groups (all P<0.01), with the better results of PRI sensation score and PRI total score in the fast acupuncture group (both P<0.05). The PRI feeling score, VAS score, and PPI score were not significantly different after treatment between the two groups (all P>0.05). The total effective rate in the fast acupuncture group was 83.3% (25/30), not significantly different from 76.7% (23/30) in the retaining needle group (P>0.05).

CONCLUSION

Fast acupuncture and retaining needle are both effective for the cervical type of cervical spondylosis, which can apparently improve the clinical symptoms. Fast acupuncture is superior to retaining acupuncture.

Polyphenols and health: Interactions between fibre, plant polyphenols and the gut microbiota

A high‐fibre diet and one rich in fruit and vegetables have long been associated with lower risk of chronic disease. There are several possible mechanisms underpinning these associations, but one likely important factor is the production of bioactive molecules from plant‐based foods by the bacteria in the colon. This links to our growing understanding of the role of the gut microbiome in promoting health. Polyphenolic‐rich plant foods have been associated with potential health effects in many studies, but the bioavailability of polyphenol compounds, as eaten, is often very low. Most of the ingested molecules enter the large intestine where they are catabolised to smaller phenolic acids that may be the key bioactive effectors. Dietary fibres, present in plant foods, are also fermented by the bacteria to short‐chain fatty acids, compounds associated with several beneficial effects on cell turnover, metabolism and eating behaviour. Polyphenols and fibre are often eaten together, but there is a lack of research investigating the interaction between these two groups of key substrates for the colonic bacteria. In a project funded by the Biotechnology and Biological Sciences Research Council Diet and Health Research Industry Club, we are investigating whether combining different fibres and polyphenol sources can enhance the production of bioactive phenolic acids to promote health. This could lead to improved dietary recommendations and to new products with enhanced potential health‐promoting actions.

Breast cancer stem-like cells can promote metastasis by activating platelets and down-regulating antitumor activity of natural killer cells

OBJECTIVE

To investigate whether cancer stem cells (CSCs) more efficiently activating platelets and evading immune surveillance than non-CSCs thus promoting metastasis.

METHODS

We enriched and identified sphere-forming cells (SFCs) and coincubated washed platelets with several platelet activators including collagen, 4T1 and SFCs. Platelet-coating tumor cells, platelet activation and TGF-β1 release were analyzed. Then natural kell cells (NK) were incubated with supernatants of different activated platelet samples what we called sample release (SR). The degranulation assay and NKG2D expression on NK cells were conducted by flow cytometry. Finally tissue factor (TF) expression of SFCs or 4T1 were evaluated by western blot.

RESULTS

Breast cancer cell line 4T1 could form spheres in serum-free medium at low adherence. Sphere-forming cells expressed high levels of the CD24-/lowCD44 + stem cell phenotype. Both sphere-forming cells or 4T1 were coated with abundant platelets while sphere-forming cells induced significantly higher expression of platelet activating receptor CD62p than 4T1 did (P < 0.01). And sphere-forming cells induced platelets to produce more TGF-β1 than 4T1 did (P < 0.01). Furthermore, sample releases induced by sphere-forming cells caused more vigorous inhibition of NK cells antitumor reactivity (P < 0.05) and reduced NKG2D expression (P < 0.01). The final results showed that sphere-forming cells expressed higher levels of TF than 4T1 (P < 0.05).

CONCLUSION

Our findings indicate that CSCs could efficiently activate platelets, induce platelets to secrete more TGF-β1, decrease NKG2D expression and inhibit antitumor activity of NK cell, compared with 4T1. And higher levels of TF expression of CSCs may account for this correlation of CSCs and platelets.

Superiorization-based multi-energy CT image reconstruction

The recently-developed superiorization approach is efficient and robust for solving various constrained optimization problems. This methodology can be applied to multi-energy CT image reconstruction with the regularization in terms of the prior rank, intensity and sparsity model (PRISM). In this paper, we propose a superiorized version of the simultaneous algebraic reconstruction technique (SART) based on the PRISM model. Then, we compare the proposed superiorized algorithm with the Split-Bregman algorithm in numerical experiments. The results show that both the Superiorized-SART and the Split-Bregman algorithms generate good results with weak noise and reduced artefacts.

Metal ion type significantly affects the morphology but not the activity of lipase–metal–phosphate nanoflowers

Using different metal ions to prepare hybrid lipase nanoflowers resulted in a variety of different morphologies, but did not significantly affect the specific activity of the enzyme.

Chlamydia psittaci exposure in pet birds

Chlamydia psittaci is a zoonotic pathogen with a wide range of avian hosts and may be transmitted to humans and cause severe disease. To assess the risk of psittacosis posed by pet birds, the seroprevalence of Chlamydia psittaci antibodies in 360 Eurasian siskins (Carduelis spinus), 289 oriental skylarks (Alauda arvensis) and 36 black-tailed grosbeaks (Coccothraustes migratorius) in Gansu province, north-western China was detected by an indirect haemagglutination assay. Twenty-seven out of 289 (9.34 %) Alauda arvensis, 45 out of 360 (12.50 %) Carduelis spinus and 2 out of 36 (5.56 %) Coccothraustes migratorius were positive for Chlamydia psittaci infection at a cut-off dilution of 1 : 16. The prevalence of Chlamydia psittaci was higher in Carduelis spinus (12.5 %) than in Alauda arvensis (9.34 %) and Coccothraustes migratorius (5.56 %); however, the differences were not statistically significant (P>0.05). Statistical analysis indicated that Chlamydia psittaci seroprevalence in adult pet birds (12.4 %, 67/540) was significantly higher than that in juvenile pet birds (4.83 %, 7/145) (P<0.01). There was no statistical difference in Chlamydia psittaci seroprevalence between male (12.4 %) and female (8.27 %) birds. To our knowledge, this is the first report indicating the seroprevalence of Chlamydia psittaci exposure in pet birds in China. Our results indicate that close contact with pet birds poses the risk of zoonotic transmission of Chlamydia psittaci.

Seroprevalence of Chlamydia psittaci infection in market-sold adult chickens, ducks and pigeons in north-western China

Chlamydia psittaci, the agent of psittacosis in humans, infects a wide range of avian species. To assess the risk of psittacosis posed by domestic birds in the urban environment, the prevalence of C. psittaci antibodies in 413 chickens (Gallus domesticus; 305 caged and 108 free-range), 334 ducks (Anas spp.; 111 caged and 223 free-range) and 312 pigeons (Columba livia) in Lanzhou, north-western China, was detected using the indirect haemagglutination assay. The specific antibodies were found in sera of 55 (13.32 %) chickens, 130 (38.92 %) ducks and 97 (31.09 %) pigeons. Statistical analysis showed that the seroprevalence of C. psittaci infection in chickens was significantly lower than that in ducks and pigeons (P<0.05). The C. psittaci seroprevalence in caged and free-range chickens was 7.54 % and 29.63 %, respectively, and the difference was statistically significant (P<0.05). The C. psittaci seroprevalence in caged and free-range ducks was 26.13 % and 45.29 %, respectively (P<0.05). To our knowledge, this is the first study indicating the presence of C. psittaci infection in market-sold chickens, ducks and pigeons in north-western China. Close contact with these birds is associated with a risk of zoonotic transmission of C. psittaci. Public education should be implemented to reduce the risk of avian to human transmission of such a pathogenic agent.

X-ray dark-field imaging modeling

Dark-field images are formed from x-ray small-angle scattering signals. The small-angle scattering signals are particularly sensitive to structural variation and density fluctuation on a length scale of several tens to hundreds of nanometers, offering a unique contrast mechanism to reveal subtle structural features of an object. In this study, based on the principle of energy conservation, we develop a physical model to describe the relationship between x-ray small-angle scattering coefficients of an object and dark-field intensity images. This model can be used to reconstruct volumetric x-ray small-angle scattering images of an object using classical tomographic algorithms. We also establish a relationship between the small-angle scattering intensity and the visibility function measured with x-ray grating imaging. The numerical simulations and phantom experiments have demonstrated the accuracy and practicability of the proposed model.

[Protective effects of ginseng-ginko extracts combination on rat primary cultured neurons induced by Abeta(1-40)]

OBJECTIVE

To observe the injury in rat primary cultured neurons induced by Abeta(1-40) and the protective effects of combination of ginseng and ginko extracts.

METHOD

Primary neurons were induced by Abeta(1-40) to establish the cell model of toxic injury. Using flow cytometry with Annexin V-FITC/PI double staining, MTP assay, transmission electron microscopy and Western blot, the appropriate concentration and duration of AP for cell model establishment were determined. The effects of extracts of ginseng and ginko (EGGB)on cellular proliferative activity, apoptotic rate, ultrastructure and caspase-3 expression were detected.

RESULT

The apoptotic rate was increased significantly after neurons were induced by 1 micromol x L(-1) Abeta(-40) for 24 h (P < 0.01). EGGB (5, 50 mg L(-1)) significantly enhanced the proliferative activity (P < 0.05). Meanwhile, EGGB (50 mg L(-1)) inhibited neuronal apoptosis and caspase-3 overexpression and improved cellular ultrastructure remarkably (P < 0.05, P < 0.01).

CONCLUSION

Abeta(1-40) could significantly induce primary cultured neurons to apoptosis in vitro. EGGB showed beneficial neuroprotective effects against neuronal apoptosis, which might be due to improving the structures of neuron and its subcellular organelles, enhancing cellular proliferative activity and inhibiting caspase-3 overexpression in neurons.

X-ray scattering tomography for biological applications

The conventional attenuation contrast imaging does not yield satisfactory sensitivity and specificity for weakly absorbing media, such as biological soft tissues. The x-ray scattering offer an important contrast mechanism to reveal structural features and density fluctuation within an object. This scattering signal carries information at the molecular and supra-molecular level, and has a tremendous implication for biomedical and other applications. In this paper, we develop a scattering imaging approach to reconstruct the electron density distribution of an object and demonstrate its feasibility in the numerical simulation.

beta-Actin is a useful internal control for tissue-specific gene expression studies using quantitative real-time PCR in the half-smooth tongue sole Cynoglossus semilaevis challenged with LPS or Vibrio anguillarum

beta-Actin has been frequently used as an internal control (gene) or as a housekeeping gene to normalize the expression of the target gene(s) or mRNA levels between different samples. However, the beta-actin expression has been shown to be influenced by the sample type and experimental conditions. If beta-actin could be used as a reference gene for the half-smooth tongue sole Cynoglossus semilaevis remains ill-defined. Here we evaluate the tissue-specific beta-actin gene expression pattern in C. semilaevis when challenged with antigenic agents namely, lipopolysaccharide (LPS) or Vibrio anguillarum employing absolute quantitative real-time PCR. The real-time PCR was performed based on the standard curve generated from recombinant plasmids. No significant differences in beta-actin expression were found between treated and untreated tissue samples. We thus conclude that beta-actin could be used as a reliable internal reference gene for real-time PCR based quantitation of gene expression studies in various tissue samples of C. semilaevis challenged with LPS or pathogenic bacteria.

Bioluminescence tomography based on the phase approximation model

A reconstruction method of bioluminescence sources is proposed based on a phase approximation model. Compared with the diffuse approximation, this phase approximation model more correctly predicts bioluminescence photon propagation in biological tissues, so that bioluminescence tomography can accurately locate and quantify the distribution of bioluminescence sources. The compressive sensing (CS) technique is applied to regularize the inverse source reconstruction to enhance numerical stability and efficiency. The numerical simulation and phantom experiments demonstrate the feasibility of the proposed approach.

OPTICAL PROPERTY CHARACTERIZATION BASED ON A PHASE FUNCTION APPROXIMATION MODEL

Recently, we generalized the Delta-Eddington phase function and applied it to the radiative transfer equation for modeling the photon propagation in biological tissue. The resultant phase approximation model was shown to be highly accurate with a wide range of optical properties, including the strongly absorbing and weakly scattering media. In this paper, we propose phase-approximation-based method for estimating the optical parameters. Specifically, we design an iterative algorithm to take advantage of both the global search ability of the differential evolution algorithm and the efficiency of the conjugate gradient method. Then, we demonstrate the feasibility and merits of the proposed method in both numerical simulation and phantom experiments.

Modeling photon propagation in biological tissues using a generalized Delta-Eddington phase function

Photon propagation in biological tissue is commonly described by the radiative transfer equation, while the phase function in the equation represents the scattering characteristics of the medium and has significant influence on the precision of solution and the efficiency of computation. In this work, we present a generalized Delta-Eddington phase function to simplify the radiative transfer equation to an integral equation with respect to photon fluence rate. Comparing to the popular diffusion approximation model, the solution of the integral equation is highly accurate to model photon propagation in the biological tissue over a broad range of optical parameters. This methodology is validated by Monte Carlo simulation.

Flux vector formulation for photon propagation in the biological tissue

We present a generalized delta-Eddington phase function to simplify the radiative transfer equation to an integral equation with respect to the photon flux vector. The solution of the integral equation is highly accurate to model the photon propagation in the biological tissue over a broad range of optical parameters, especially in the visible light spectrum where the diffusion approximation breaks down. The methodology is validated in the Monte Carlo simulation and can be applied in various optical imaging applications.

Study of the metabolism on tobacco-specific N-nitrosamines in the rabbit by solid-phase extraction and liquid chromatography-tandem mass spectrometry

Metabolism of four tobacco-specific N-nitrosamines (TSNAs), N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been studied by solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL) was used as internal standard. SPE and LC-MS-MS was found to be a rapid, simple, sensitive, and selective method for analysis of TSNAs in rabbit serum. The relative standard deviation (R.S.D., n = 6) for analysis of 5 ng mL(-1) and 0.5 ng mL(-1) standards and of serum sample spiked with 5 ng mL(-1) standards of five TSNAs was 2.1-11% and recovery of 5 ng mL(-1) standards from serum was 100.2-112.9%. A good linear relationship was obtained between peak area ratio and concentration in the range of 0.2-100 ng mL(-1) for NNAL and 0.5-100 ng mL(-1) for other four TSNAs, with correlation coefficients (R2) >0.99 (both linear and log-log regression). Detection limits for standards in solvent were between 0.04 and 0.10 ng mL(-1). Doses of TSNAs administered to rabbits via the auricular vein were 4.67 microg kg(-1) and 11.67 microg kg(-1), in accordance with the different levels in cigarettes. Metabolic curves were obtained for the four TSNAs and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of NNK; on the basis of these curves we modeled metabolic kinetic equations for these TSNAs by nonlinear curve fitting.

Determination of tobacco-specific N-nitrosamines in rabbit serum by capillary zone electrophoresis and capillary electrophoresis-electrospray ionization-mass spectrometry with solid-phase extraction

In this paper, we propose a new strategy for separation and determination of tobacco-specific N-nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE-MS associated with SPE. Six TSNAs: N'-nitrosonornicotine, N'-nitrosoanatabine, N'-nitrosoanabasine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH 2.5) and another with citrate buffer (pH 2.4), as well as a CE-MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE-MS method, an optimized sheath liquid consisted of methanol-water was used at a flow rate of 10 muL/min. With SPE procedure, our proposed CE-MS method was successfully applied to determine TSNAs after 15 min metabolism in rabbits. A comparison study between CZE and CE-MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE-MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC-MS, the new CE-MS method is expected to be an alternative to the LC-MS method and applied to study the metabolism of TSNAs.

Regulation of CO on heterocyst differentiation and nitrate uptake in the cyanobacterium Anabaena sp. PCC 7120

AIMS

The aim of the present investigation was to study the effects of different inorganic carbon and nitrogen sources on nitrate uptake and heterocyst differentiation in the culture of cyanobacterium Anabaena sp. PCC 7120.

METHODS AND RESULTS

Anabaena was cultivated in media BG11 containing combined nitrogen and supplementary NaHCO3 or CO2. Cell growth, heterocyst differentiation, nitrate reductase (NR, EC 1.7.7.2), glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) and NO uptake were analysed. The cells cultivated in BG11(0) medium with aeration were taken as reference. Experimental results showed that the differentiation frequency of heterocysts when the cells were cultivated with elevated CO2 was higher than that of the cells grown with air or bicarbonate. Heterocysts appeared unexpectedly when CO2 was introduced into the medium containing nitrate. However, no heterocysts emerged when CO2 was added to medium containing NH or urea, or when NaHCO3 was supplied to the medium with nitrate. Both nitrate uptake rate and nitrate reduction enzyme activity were depressed by the supplement of CO2 to the culture. The activity of G6PDH was enhanced with the increase in heterocyst differentiation frequency.

CONCLUSION

CO2 might compete with NO for energy and electrons in the uptake process and CO2 appears favoured. This led to a high intracellular C/N ratio and a relative N limitation. So the process of heterocyst differentiation was activated to supplement nitrogen uptake.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provided an attractive possibility to form more heterocysts by rapid growth of Anabaena cells cultivated in the medium containing nitrate in order to increase nitrogen fixation and hydrogen production.