Aspartate β-hydroxylase disrupts mitochondrial DNA stability and function in hepatocellular carcinoma

The mechanism of aberrant mitochondrial genome and function in hepatocellular carcinoma (HCC) remains largely unknown. Our previous study demonstrated an increased expression of aspartate β-hydroxylase (ASPH) in HCC tissues, which was associated with tumor invasiveness and a worse prognosis. Currently, we unexpectedly observed the presence of ASPH in purified mitochondrial protein fraction. In addition, immunostaining of both exogenously and endogenously expressed ASPH showed a colocalization with mitochondrial biomarkers. This study aimed to investigate whether the mitochondrial ASPH is involved in mitochondrial malfunction in HCC. Our results showed that ASPH overexpression in HCC tissues was correlated with decreased copy numbers of displacement loop (D-loop) and NADH dehydrogenase subunit 1 (ND-1) and enhanced D-loop mutation, suggesting the disrupted mitochondrial DNA (mtDNA) stability. The reduced mtDNA copy numbers were associated with aggressive clinicopathological features of HCC. The loss of mtDNA integrity induced by enforced expression of ASPH was accompanied with mitochondrial dysfunction, which was characterized by the aberrant mitochondrial membrane potential, decreased ATP generation and enhanced reactive oxygen species. In contrast, knocking down ASPH by siRNA in HCC cell lines showed the opposite impact on mtDNA integrity and function. Mass spectrometry and co-immunoprecipitation further identified that ASPH interacted with histone H2A member X (H2AX). ASPH overexpression diminished the interaction between H2AX and mitochondrial transcription factor A (mtTFA), an important DNA-binding protein for mtDNA replication, which then reduced the binding of mtTFA to D-loop region. Collectively, our results demonstrate that ASPH overexpression disrupts the mtDNA integrity through H2AX-mtTFA signal, thereby affecting mitochondrial functions in HCC.

Preparation and evaluation of cefquinome-loaded gelatin microspheres and the pharmacokinetics in pigs

Cefquinome (CEF) is widely used for veterinary clinical applications because of its broad spectrum and high efficiency. However, frequent administrations are required due to its short elimination half-life. In this study, cefquinome sulfate gelatin microspheres (CEF-GMS) were prepared as a sustained-release formulation using emulsion chemical cross-linking technique. Physical properties, stability, sustained-release property in vitro, and pharmacokinetics in pigs were assessed. The morphology of CEF-GMS showed a good sphericity with porous structure on the surface, and the mean diameter was 8.80 ± 0.78 μm, with 90.60 ± 3.98% of the total in the range of 5-20 μm. There were no significant changes of all estimated indexes in the stability tests. In vitro drug release study showed that the release of CEF from CEF-GMS was much slower than that from crude CEF in a release medium. Pharmacokinetic characteristics were evaluated following intramuscular administration of CEF-GMS or Cefquinome sulfate injection (CEF-Inj) in pigs at a dosage of 4 mg CEF/kg body weight. The plasma drug concentration-time data of CEF-GMS and CEF-Inj were both best fitted by two-compartment models with first-order absorption, and the elimination half-life of CEF-GMS was almost 10 times that of CEF-Inj. Overall, CEF-GMS might be used as a sustained-release formulation of CEF for veterinary clinical applications.

miR-17-3p Contributes to Exercise-Induced Cardiac Growth and Protects against Myocardial Ischemia-Reperfusion Injury

Limited microRNAs (miRNAs, miRs) have been reported to be necessary for exercise-induced cardiac growth and essential for protection against pathological cardiac remodeling. Here we determined members of the miR-17-92 cluster and their passenger miRNAs expressions in two distinct murine exercise models and found that miR-17-3p was increased in both. miR-17-3p promoted cardiomyocyte hypertrophy, proliferation, and survival. TIMP-3 was identified as a direct target gene of miR-17-3p whereas PTEN was indirectly inhibited by miR-17-3p. Inhibition of miR-17-3p in vivo attenuated exercise-induced cardiac growth including cardiomyocyte hypertrophy and expression of markers of myocyte proliferation. Importantly, mice injected with miR-17-3p agomir were protected from adverse remodeling after cardiac ischemia/reperfusion injury. Collectively, these data suggest that miR-17-3p contributes to exercise-induced cardiac growth and protects against adverse ventricular remodeling. miR-17-3p may represent a novel therapeutic target to promote functional recovery after cardiac ischemia/reperfusion.

Patients with HBV-related acute-on-chronic liver failure have increased concentrations of extracellular histones aggravating cellular damage and systemic inflammation

Acute-on-chronic liver failure (ACLF) is the most common type of liver failure and associated with grave consequences. Systemic inflammation has been linked to its pathogenesis and outcome, but the identifiable triggers are absent. Recently, extracellular histones, especially H4, have been recognized as important mediators of cell damage in various inflammatory conditions. This study aimed to investigate whether extracellular histones have clinical implications in patients with hepatitis B virus (HBV)-related ACLF. One hundred and twelve patients with HBV-related ACLF, 90 patients with chronic hepatitis B, 88 patients with HBV-related liver cirrhosis and 40 healthy volunteers were entered into this study. Plasma histone H4 levels, cytokine profile and clinical data were obtained. Besides, patient's sera were incubated overnight with human L02 hepatocytes or monocytic U937 cells in the presence or absence of antihistone H4 antibody, and cellular damage and cytokine production were evaluated. We found that plasma histone H4 levels were greatly increased in patients with ACLF as compared with chronic hepatitis B, liver cirrhosis and healthy control subjects and were significantly associated with disease severity, systemic inflammation and outcome. Notably, ACLF patients' sera incubation decreased cultured L02 cell integrity and induced profound cytokine production in the supernatant of U937 cells. Antihistone H4 antibody treatment abrogated these adverse effects, thus confirming a cause-effect relationship between extracellular histones and organ injury/dysfunction. The data support the hypothesis that the increased extracellular histone levels in ACLF patients may aggravate disease severity by inducing cellular injury and systemic inflammation. Histone-targeted therapies may have potentially interventional value in clinical practice.

Construction and identification of a model for HJURP gene defect expression in human embryo villus cells

OBJECTIVES

To construct a lentiviral vector for RNA interference (RNAi) of the HJURP gene and to identify the silencing efficiency in the human embryo villus cells and to provide a human embryo villus cells multiplication and chromosome segregation.

MATERIALS AND METHODS

In accordance with the study, three specific sequences of siRNA targeting HJURP gene were designed, synthesized, then the complementary DNA containing both sense and antisense oligonucleotides of the targeting sequences were annealed and inserted into the lentiviral vector.The correct clonings were confirmed by PCR and sequencing. The most effective recombinant lentivirus vector was screened, and the recombinant plasmids with the lentivirus packaging mixes were co-transfected into 293T cells to obtain packaged lentivirus particles. Then viral titer was determined. The silencing efficiency of target gene in human embryo villus cells was detected by Real-Time PCR.

RESULTS

DNA sequencing showed that the shRNA sequence was successfully inserted into the lentivirus vector. The recombinant lentiviral vector was successfully transfected into 293T cells. The recombinant lentivirus had a titer of 108 PFU/ml. After silencing HJURP gene in human embryo villus cells, the expression level of HJURP mRNA decreased significantly and the RNAi efficiency was greater than 70%.

CONCLUSION

A lentiviral shRNA expression vector targeting the HJURP gene was successfully constructed and may effectively silence the target gene at a cellular level, which provides a experimental model for the influence of HJURP gene expressing inhibition on human embryo villus cells multiplication and chromosome segregation.

Understanding hydraulic fracturing: a multi-scale problem

Despite the impact that hydraulic fracturing has had on the energy sector, the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nanometres to kilometres. We characterize flow and transport in shale formations across and between these scales using integrated computational, theoretical and experimental efforts/methods. At the field scale, we use discrete fracture network modelling to simulate production of a hydraulically fractured well from a fracture network that is based on the site characterization of a shale gas reservoir. At the core scale, we use triaxial fracture experiments and a finite-discrete element model to study dynamic fracture/crack propagation in low permeability shale. We use lattice Boltzmann pore-scale simulations and microfluidic experiments in both synthetic and shale rock micromodels to study pore-scale flow and transport phenomena, including multi-phase flow and fluids mixing. A mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs. Finally, we discuss the potential of CO2 as an alternative working fluid, both in fracturing and re-stimulating activities, beyond its environmental advantages.This article is part of the themed issue 'Energy and the subsurface'.

Crucial Role of miR-433 in Regulating Cardiac Fibrosis

Dysregulation of microRNAs has been implicated in many cardiovascular diseases including fibrosis. Here we report that miR-433 was consistently elevated in three models of heart disease with prominent cardiac fibrosis, and was enriched in fibroblasts compared to cardiomyocytes. Forced expression of miR-433 in neonatal rat cardiac fibroblasts increased proliferation and their differentiation into myofibroblasts as determined by EdU incorporation, α-SMA staining, and expression levels of fibrosis-associated genes. Conversely, inhibition of miR-433 exhibited opposite results. AZIN1 and JNK1 were identified as two target genes of miR-433. Decreased level of AZIN1 activated TGF-β1 while down-regulation of JNK1 resulted in activation of ERK and p38 kinase leading to Smad3 activation and ultimately cardiac fibrosis. Importantly, systemic neutralization of miR-433 or adeno-associated virus 9 (AAV9)-mediated cardiac transfer of a miR-433 sponge attenuated cardiac fibrosis and ventricular dysfunction following myocardial infarction. Thus, our work suggests that miR-433 is a potential target for amelioration of cardiac fibrosis.

Cell-based evaluation of a novel Dictyophora indusiata polysaccharide against oxidative-induced erythrocyte hemolysis

The protective effect of a polysaccharide from Dictyophora indusiata(DP1)against oxidative hemolysis was comprehensively evaluated. The 2, 2-azobis (2-amidino-propane) dihydrochloride (AAPH)-induced erythrocyte hemolysis assay showed that DP1 exhibited excellent anti-hemolytic activity(87.4% hemolysis suppression ratio at 20 nmol/mL). Also, the formation of conjugated diene induced by cupric chloride (CuCl2) in plasma was significantly inhibited by DP1. Besides, DP1 could effectively inhibit AAPH-induced overproduction of reactive oxygen species (81.5% inhibition at 20 nmol/mL) and alleviated the enhancement of intracellular antioxidant enzymes including superoxide dismutase(SOD), glutathione peroxidase (GPX) and catalase (CAT) activities. Also, the malondialdehyde (MDA) formation caused by oxidative stress was suppressed by 57.0% at DP1 concentration of 20 nmol/mL. Taken together, the possible intracellular antioxidant detoxifying mechanism of DP1 was probably via preserving the activities of the antioxidant enzymes (SOD, GPx and CAT) as well as inhibiting lipid peroxidation, and thus alleviated erythrocytes oxidation and plasma oxidation.

Effects of whole-body vibration training with quadriceps strengthening exercise on functioning and gait parameters in patients with medial compartment knee osteoarthritis: a randomised controlled preliminary study

OBJECTIVE

To compare the effects of whole-body vibration training (WBVT) with quadriceps strengthening exercise (QSE) with QSE alone on functioning and gait parameters in patients with medial compartment knee osteoarthritis.

DESIGN

Randomised controlled preliminary study.

SETTING

Department of Rehabilitation Medicine, West China Hospital, Chengdu, Sichuan, People's Republic of China.

SUBJECTS

Thirty-nine patients with medial compartment knee osteoarthritis.

INTERVENTIONS

Participants were assigned at random to one of two groups.

MAIN MEASURES

Visual analogue scale (VAS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), timed up and go test (TUG), 6-minute walk distance test (6MWD), and three-dimensional gait analysis during level walking at baseline, 12 weeks and 16 weeks (follow-up).

RESULTS

Compared with baseline, significant improvements in VAS, all WOMAC scales, TUG, 6MWD and all spatiotemporal parameters were seen in both the WBVT+QSE group and the QSE alone group at 12 and 16 weeks. However, the WBVT+QSE group showed greater improvements than the QSE alone group in WOMAC scales (physical function), TUG, 6MWD and cadence at 12 weeks. No differences were found between the WBVT+QSE and QSE alone groups in VAS, WOMAC scales (pain, stiffness), kinematic and kinetic gait parameters, and other spatiotemporal parameters at 12 weeks and 16 weeks.

CONCLUSION

Over a 3-month period, WBVT in combination with QSE improved symptoms, physical function and spatiotemporal parameters in patients with medial compartment knee osteoarthritis, and led to greater improvement than QSE alone in WOMAC scales (physical function), TUG, 6MWD and cadence.

Repression of TIF1γ by SOX2 promotes TGF-β-induced epithelial-mesenchymal transition in non-small-cell lung cancer

TIF1γ is a novel regulator of transforming growth factor (TGF)-β/Smad signaling. Our previous studies show that dysregulated expression of transcriptional intermediary factor 1 γ (TIF1γ) and abnormal TGF-β/Smad signaling are implicated in non-small-cell lung cancer (NSCLC) separately. However, how TIF1γ contributes to NSCLC by controlling TGF-β/Smad signaling is poorly understood. Here, we investigated the mechanistic role of TIF1γ in TGF-β-induced epithelial-mesenchymal transition (EMT), as well as a link between TIF1γ and SOX2 in NSCLC. We show that TIF1γ is a downstream target of SOX2 in NSCLC cells. SOX2 overexpression negatively regulated TIF1γ promoter activity and thereby attenuated TIF1γ mRNA and protein expression levels; SOX2 knockdown significantly enhanced TIF1γ promoter activity and augmented TIF1γ expression. Moreover, TIF1γ mRNA expression was downregulated in human NSCLC tissues and negatively correlated with SOX2 protein, which was upregulated in NSCLC tissues. Importantly, knockdown of TIF1γ or SOX2 overexpression augmented SMAD4 (human Mad (mothers against decapentaplegic)-related homologous protein 4)-dependent transcriptional responses, and enhanced TGF-β-induced EMT and human NSCLC cell invasion; knockdown of SOX2 impaired TGF-β-induced EMT and NSCLC cell invasion. In an in vivo model of metastasis, knockdown of TIF1γ promotes NSCLC cell metastasis. In addition, our data suggested that TIF1γ inhibited TGF-β-induced EMT through competing with SMAD4 in NSCLC cells. Taken together, our findings reveal a new mechanism by which SOX2-mediated transcription repression of TIF1γ promotes TGF-β-induced EMT in NSCLC.

MicroRNA-132/212 family enhances arteriogenesis after hindlimb ischaemia through modulation of the Ras-MAPK pathway

Arteriogenesis is a complicated process induced by increased local shear-and radial wall-stress, leading to an increase in arterial diameter. This process is enhanced by growth factors secreted by both inflammatory and endothelial cells in response to physical stress. Although therapeutic promotion of arteriogenesis is of great interest for ischaemic diseases, little is known about the modulation of the signalling cascades via microRNAs. We observed that miR-132/212 expression was significantly upregulated after occlusion of the femoral artery. miR-132/212 knockout (KO) mice display a slower perfusion recovery after hind-limb ischaemia compared to wildtype (WT) mice. Immunohistochemical analysis demonstrates a clear trend towards smaller collateral arteries in KO mice. Although Ex vivo aortic ring assays score similar number of branches in miR-132/212 KO mice compared to WT, it can be stimulated with exogenous miR-132, a dominant member of the miR-132/212 family. Moreover, in in vitro pericyte-endothelial co-culture cell assays, overexpression of miR-132 and mir-212 in endothelial cells results in enhanced vascularization, as shown by an increase in tubular structures and junctions. Our results suggested that miR-132/212 may exert their effects by enhancing the Ras-Mitogen-activated protein kinases MAPK signalling pathway through direct inhibition of Rasa1, and Spred1. The miR-132/212 cluster promotes arteriogenesis by modulating Ras-MAPK signalling via direct targeting of its inhibitors Rasa1 and Spred1.

Ultrasound and microbubble-induced local delivery of MicroRNA-based therapeutics

MicroRNAs are involved in many pathologic processes and are a promising target for therapeutic intervention. However, successful, localized delivery of microRNA-based therapeutics is lacking. In this study, cationic ultrasound-responsive microbubbles (MBs) were used to deliver microRNA blockers and mimics in vitro and in vivo. Cationic MBs successfully delivered microRNA blockers to human endothelial cells on ultrasound (US) exposure in vitro. This in vitro US protocol did not successfully deliver microRNA mimics to skeletal muscle of mice, whereas an US protocol that is routinely used for contrast imaging did. Additionally, we used cationic MBs and US to locally deliver antimiR and antagomiR molecules with US causing inertial cavitation. Delivery of antimiR to the extracellular compartments of the muscle was only slightly increased, whereas delivery of antagomiR to the capillaries, myocytes and extracellular space was significantly increased. AntagomiR seems to be a more suitable microRNA blocker than antimiR for use in combination with MBs and US for local delivery.

Retrospective analysis of factors affecting the efficacy of surgical treatment of the scar

AIM

The scar is a major problem in the medical profession. Its timely treatment is very important for the better outcome of the scar treatment and for the improvement of the life quality of the patients. The aim of this study was retrospectively analyzed the epidemiological characteristics affecting the efficacy of the scar surgical treatment of the people in the western part of China.

METHODS

Total 414 scar cases were retrospectively analyzed to clarify the epidemiological characteristics and the factors affecting the scar surgical treatment efficacy. The factors included were sex, age, area distribution, treatment seasons, injury sites, injury causes, and the time from scarring to the surgical treatment. All scar cases were surgically treated with the repairing technology including skin graft, flap and soft tissue dilation.

RESULTS

There were 206 males and 208 females with the average age 20.53±12.9 years (age range 1-68 years). The patient proportions in the age groups of 0-20, 21-40 and >40 years were 61.4% (254 cases), 29.2% (121 cases), and 9.4% (39 cases) respectively. The patient's attendance rate reached the highest during the summer and winter. Most patients were from the rural areas with an increasing tendency each year. The burn scars were the most abundant and the injury sites were mostly the head and face. Univariate analysis showed that the time from scarring to the surgical treatment and the injury sites were significantly influenced the scar surgical treatment efficacy. Logistic regression analysis demonstrated that the injured sites of the head and face significantly influenced the scar surgical treatment efficacy.

CONCLUSION

With the development of economy in China, more scar patients especially younger and children visit doctors predominantely from the rural areas. Usually, they get their scars in the exposed area of their bodies (head and face) which seriously affect the patient's appearance and function. Factors influencing the scar surgical treatment efficacy has important clinical significance of prevention and treatment.

The inhibitory role of miR-214 in cervical cancer cells through directly targeting mitochondrial transcription factor A (TFAM)

Mitochondrial transcription factor A (TFAM) is a high-mobility group (HMG) protein and acts as a key regulator in mitochondrial DNA (mtDNA) replication, transcription, and inheritance. Accumulating evidence has demonstrated that TFAM plays an important role in tumorigenesis; however, the regulatory mechanism of TFAM in cervical cancer has not been revealed. In the current study, the au- thors found that with malignancy of cervical cancer, the protein expression of TFAM was gradually increased, while the expression of miRNA-214 was gradually downregulated. They further identified that TFAM is a target of miR-214. Forced overexpression of miRNA-214 significantly suppressed cell proliferation, cell cycle progression, colony-formation, and migration of cervical cancer Hela and Caski cells; however, upregulation of TFAM notably promoted cell proliferation, cell cycle progression, colony-formation, and migration of Hela and Caski cells. The authors further showed that miR-214 enhanced the susceptibility of Hela and Caski cells to the chemotherapy drug cisplatin. In conclusion, the current study provides a new sight for the regulatory pattern of miRNA-214 and TFAM in cervical cancer in vitro, indicating that miRNA-214 and MTFA may become important candidates for developing promising therapeutic strategies for the treatment of cervical cancer.

Neuroprotective effects of LBP on brain ischemic reperfusion neurodegeneration

AIM

The present study was conducted to investigate whether LBP had a protective effect on cerebral ischemic reperfusion injury and to determine the possible mechanisms.

MATERIALS AND METHODS

Male Kunming (KM) mice were used to make the model cerebral artery occlusion/reperfusion (MCAO/R). The behavioral test was used to measure neurological deficit scores for evaluation of ischemic reperfusion damage of brain. The change of electroencephalograph (EEG) was monitored by Model SMUP-E Bio-electric Signals Processing System. The infarction area of brain was assessed in brain slices with 2% solution of 2,3,5-triphenyl tetrazolium chloride (TTC). Spectrophotometric assay was used to determine the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and lactate dehydrogenase (LDH), contents of malondialdehyde (MDA) and adenosine triphosphate (ATP) of the brain.

RESULTS

The results showed that LBP at doses of 20 and 40 mg/kg markedly decreased the neurological deficit scores and the infarction area in MCAO/R mice. At the same time, LBP significantly decreased MDA content, and increased SOD, GSH-Px, CAT, LDH activities in ischemic reperfusion brain.

CONCLUSIONS

These suggest that LBP might act as a potential neuroprotective agent against the cerebral reperfusion-induced injury in the brain through reducing lipid peroxides, scavenging free radicals, and improving the energy metabolism.

Alterations in metabolic pathways and networks in Alzheimer's disease

The pathogenic mechanisms of Alzheimer's disease (AD) remain largely unknown and clinical trials have not demonstrated significant benefit. Biochemical characterization of AD and its prodromal phase may provide new diagnostic and therapeutic insights. We used targeted metabolomics platform to profile cerebrospinal fluid (CSF) from AD (n=40), mild cognitive impairment (MCI, n=36) and control (n=38) subjects; univariate and multivariate analyses to define between-group differences; and partial least square-discriminant analysis models to classify diagnostic groups using CSF metabolomic profiles. A partial correlation network was built to link metabolic markers, protein markers and disease severity. AD subjects had elevated methionine (MET), 5-hydroxyindoleacetic acid (5-HIAA), vanillylmandelic acid, xanthosine and glutathione versus controls. MCI subjects had elevated 5-HIAA, MET, hypoxanthine and other metabolites versus controls. Metabolite ratios revealed changes within tryptophan, MET and purine pathways. Initial pathway analyses identified steps in several pathways that appear altered in AD and MCI. A partial correlation network showed total tau most directly related to norepinephrine and purine pathways; amyloid-β (Ab42) was related directly to an unidentified metabolite and indirectly to 5-HIAA and MET. These findings indicate that MCI and AD are associated with an overlapping pattern of perturbations in tryptophan, tyrosine, MET and purine pathways, and suggest that profound biochemical alterations are linked to abnormal Ab42 and tau metabolism. Metabolomics provides powerful tools to map interlinked biochemical pathway perturbations and study AD as a disease of network failure.

Abstract P4-06-21: Matrix Metalloproteinase 2 in Tumor Cell-Induced Platelet Aggregation: Regulation by Cryptotanshinone

Background: A correlation exists between the ability of tumor cells to aggregate platelets and their tendency to metastasize. Tumor cell-induced platelet aggregation (TCIPA) facilitates the embolization of the vasculature with tumor cells and the formation of metastatic foci. It is well documentedthat matrix metalloproteinases (MMPs) play an integral part in tumor spread and the metastatic cascade.

Material and Methods: Therefore, we have examined the role of MMPs during TCIPA and its regulation by Cryptotanshinone in vitro. Human breast cancer cell line MCF-7 and MDA-MB-231 induced TCIPA in a concentration dependent manner that was monitored by aggregometry. This aggregation resulted in the release of MMP-2 from platelets and cancer cells, as measured by RT-PCR.

Results:MCF-7 cells released significantly more MMP-2 than MDA-MB-231 cells and were more efficacious in inducing TCIPA. Inhibition of MMP-2 with phenanthroline (1-1000 mM), a synthetic inhibitor of MMPs, and by neutralizing anti-MMP-2 antibody (10 mg/ml) reduced TCIPA induced by MCF-7 cells. TCIPA was abolished by simultaneous inhibition of platelet function with acetylsalicylic acid (100 mM; thromboxane pathway inhibitor), apyrase (250 mg/ml; ADP pathway inhibitor), and phenanthroline. Cryptotanshinone inhibited TCIPA and MMP-2 release from platelets and tumor cells.

Discussion:We conclude that (a) human Human breast cancer cells aggregate platelets via mechanism (s) that are mediated, in part, by MMP-2; (b) Cryptotanshinone inhibits TCIPA, in part, by attenuating the release of MMP-2.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-06-21.

Downregulation of Kv4.2 channels mediated by NR2B-containing NMDA receptors in cultured hippocampal neurons

Somatodendritic Kv4.2 channels mediate transient A-type potassium currents (I(A)), and play critical roles in controlling neuronal excitability and modulating synaptic plasticity. Our studies have shown an NMDA receptor-dependent downregulation of Kv4.2 and I(A). NMDA receptors are heteromeric complexes of NR1 combined with NR2A-NR2D, mainly NR2A and NR2B. Here, we investigate NR2B receptor-mediated modulation of Kv4.2 and I(A) in cultured hippocampal neurons. Application of glutamate caused a reduction in total Kv4.2 protein levels and Kv4.2 clusters, and produced a hyperpolarized shift in the inactivation curve of I(A). The effects of glutamate on Kv4.2 and I(A) were inhibited by pretreatment of NR2B-selective antagonists. NR2B-containing NMDA receptors are believed to be located predominantly extrasynaptically. Like application of glutamate, selective activation of extrasynaptic NMDA receptors caused a reduction in total Kv4.2 protein levels and Kv4.2 clusters, which was also blocked by NR2B-selective antagonists. In contrast, specific stimulation of synaptic NMDA receptors had no effect on Kv4.2. In addition, the influx of Ca(2+) was essential for extrasynaptic modulation of Kv4.2. Calpain inhibitors prevented the reduction of total Kv4.2 protein levels following activation of extrasynaptic NMDA receptors. These results demonstrate that the glutamate-induced downregulation of Kv4.2 and I(A) is mediated by NR2B-containing NMDA receptors and is linked to proteolysis by calpain, which might contribute to the development of neuronal hyperexcitability and neurodegenerative diseases.

Clinical study of mini-nutritional assessment for older Chinese inpatients

BACKGROUND

Malnutrition is a common problem in older patients. Early detection of malnutrition is an important task in clinical practice. The MNA has become an extensively used tool to evaluate nutritional status in European countries and the United States.

OBJECTIVE

We evaluated the Mini-Nutritional Assessment (MNA) test and the short-form MNA (MNA-SF) test as screening tools for malnutrition in older Chinese inpatients and focused on finding an optimal cutoff point for MNA total score and MNA-SF score.

DESIGN

One hundred eighty-four older Chinese inpatients were enrolled in this study from July to August 2006. Nutritional assessment included MNA, anthropometric measurements, and biochemical markers.

RESULTS

According to the original cutoff point of the full MNA, 19.6% of those assessed were malnourished, 53.2% were at risk of malnutrition and 27.2% were well nourished. Correlations were found between MNA, MNA-SF and body mass index, triceps skinfold thickness, serum albumin, lymphocyte count, hemoglobin, lymphocyte ratio. With the most proper cutoff point lower than 19 indicating malnutrition, when using serum albumin (< 35.0 g/L) as the indicator, the sensitivity and specificity of the MNA total score were 0.6286 and 0.7466; when using BMI (< 18.5 kg/m2) as the indicator, the sensitivity and specificity were 0.8636 and 0.7469. The incidence rate of malnutrition was 32.6%. The most proper cutoff point of MNA-SF was lower than 12.

CONCLUSION

The MNA and MNA-SF were useful tools to identify older Chinese inpatients with malnutrition. However, the cutoff point of the MNA should be modulated for this population.

dRecQ4 is required for DNA synthesis and essential for cell proliferation in Drosophila

BACKGROUND

The family of RecQ DNA helicases plays an important role in the maintenance of genomic integrity. Mutations in three of the five known RecQ family members in humans, BLM, WRN and RecQ4, lead to disorders that are characterized by predisposition to cancer and premature aging.

METHODOLOGY/PRINCIPAL FINDINGS

To address the in vivo functions of Drosophila RecQ4 (dRecQ4), we generated mutant alleles of dRecQ4 using the targeted gene knock-out technique. Our data show that dRecQ4 mutants are homozygous lethal with defects in DNA replication, cell cycle progression and cell proliferation. Two sets of experiments suggest that dRecQ4 also plays a role in DNA double strand break repair. First, mutant animals exhibit sensitivity to gamma irradiation. Second, the efficiency of DsRed reconstitution via single strand annealing repair is significantly reduced in the dRecQ4 mutant animals. Rescue experiments further show that both the N-terminal domain and the helicase domain are essential to dRecQ4 function in vivo. The N-terminal domain is sufficient for the DNA repair function of dRecQ4.

CONCLUSIONS/SIGNIFICANCE

Together, our results show that dRecQ4 is an essential gene that plays an important role in not only DNA replication but also DNA repair and cell cycle progression in vivo.

Feeding, oviposition and survival of Liriomyza trifolii (Diptera: Agromyzidae) on Bt and non-Bt cottons

The effects of Bt transgenic cottons (Bt-I expressing cry1Ac and Bt-II expressing cry1Ab and cry2Ab or cry1Ab and cry1Fa) and non-Bt cottons on feeding, oviposition and longevity of adults, and development and survival of Liriomyza trifolii larvae were studied under laboratory conditions; and infestation on four Bt and two non-Bt cotton traits were investigated under field conditions. Laboratory choice and no-choice tests showed that L. trifolii adults were capable of distinguishing between Bt cottons and non-Bt cottons. In a choice test on younger plants (4-5 leaves), the adults were found more often and made more feeding punctures (FP) on non-Bt cottons than on Bt cottons. On older plants (8-9 leaves), adults made the most FP on non-Bt cotton followed by those on Bt-II cottons and the least on Bt-I cotton. The females oviposited more eggs (6.7 eggs per leaf) on non-Bt cotton than on Bt-I (1.7 eggs per leaf) and Bt-II (0.8 eggs per leaf) cottons on younger plants and oviposited similar numbers of eggs (0.7-1.3 eggs per leaf) on non-Bt and Bt cottons on older plants. In a no-choice test, the females also fed more FP on non-Bt cottons than on Bt cottons on both younger and older plants. The females oviposited more eggs (15.6 eggs per leaf) on non-Bt cotton than on Bt-I (8.2 eggs per leaf) and Bt-II (6.5 eggs per leaf) cottons on younger plants and similar numbers of eggs (2.5-3.3 eggs per leaf) on non-Bt and Bt cottons on older plants. Larval and puparial survivals were not different among Bt and non-Bt cottons. The occurrence and damage of leafminers on cottons in the field showed that L. trifolii infested more plants and leaves and had more mines on non-Bt cotton than on Bt cottons.

Enhancement of inhibitory synaptic transmission in large aspiny neurons after transient cerebral ischemia

Large aspiny neurons and most of the GABAergic interneurons survive transient cerebral ischemia while medium spiny neurons degenerate in 24 h. Expression of a long-term enhancement of excitatory transmission in medium spiny neurons but not in large aspiny neurons has been indicated to contribute to this selective vulnerability. Because neuronal excitability is determined by the counterbalance of excitation and inhibition, the present study examined inhibitory synaptic transmission in large aspiny neurons after ischemia in rats. Transient cerebral ischemia was induced for 22 min using the four-vessel occlusion method and whole-cell voltage-clamp recording was performed on striatal slices. The amplitudes of evoked inhibitory postsynaptic currents in large aspiny neurons were significantly increased at 3 and 24 h after ischemia, which was mediated by the increase of presynaptic release. Postsynaptic responses were depressed at 24 h after ischemia. Inhibitory postsynaptic currents could be evoked in large aspiny neurons at 24 h after ischemia, suggesting that they receive GABAergic inputs from the survived GABAergic interneurons. Muscimol, a GABA(A) receptor agonist, presynaptically facilitated inhibitory synaptic transmission at 24 h after ischemia. Such facilitation was dependent on the extracellular calcium and voltage-gated sodium channels. The present study demonstrates an enhancement of inhibitory synaptic transmission in large aspiny neurons after ischemia, which might reduce excitotoxicity and contribute, at least in part, to the survival of large aspiny neurons. Our data also suggest that large aspiny neurons might receive inhibitory inputs from GABAergic interneurons.

Ensuring the safety of living kidney donors and recipients in China through ethics committee oversight: an early experience

In 2007, the Regulation on Human Organ Transplantation was enacted in China requiring the establishment of ethics committees to oversee living donor organ transplantation and establishing specific requirements that must be met. We established an Ethics Committee on Organ Transplantation at Peking University Third Hospital, and described its composition, its methods and operating procedures in the examination and approval of living-related donor kidney transplantation (LRDKT) and our initial experience. All 60 proposed cases of LRDKT were presented to the Ethics Committee for discussion, among which 53 cases were approved and seven cases were disapproved due to a variety of reasons that are discussed. The Ethics Committee on Organ Transplantation plays an important role in the ethical oversight of living-related donor organ transplantation in order to ensure to the greatest extent possible the safety, rights and interests of donors and recipients.