Dissolved xylan inhibits cellulosome-based saccharification by binding to the key cellulosomal component of Clostridium thermocellum.

Polysaccharides derived from lignocellulose are promising sustainable carbon sources. Cellulosome is a supramolecular machine integrating multi-function enzymes for effective lignocellulose bio-saccharification. However, how various non-cellulose components of lignocellulose affect the cellulosomal saccharification is hitherto unclear. This study first investigated the stability and oxygen sensitivity of the cellulosome from Clostridium thermocellum during long-term saccharification process. Then, the differential inhibitory effects of non-cellulose components, including lignin, xylan, and arabinoxylan, on the cellulosome-based saccharification were determined. The results showed that lignin played inhibitory roles by non-productively adsorbing extracellular proteins of C. thermocellum. Differently, arabinoxylan preferred to bind with the cellulosomal components. Almost no adsorption of cellulosomal proteins on solid xylan was detected. Instead, xylan in water-dissolved form interacted with the cellulosomal proteins, especially the key exoglucanase Cel48S, leading to the xylan inhibitory effect. Compared to xylan, xylooligosaccharides influenced the cellulosome activity slightly. Hence, this work demonstrates that the timely hydrolysis or removal of dissolved xylan is important for cellulosome-based lignocellulose saccharification.

Coordinated ß-glucosidase activity with the cellulosome is effective for enhanced lignocellulose saccharification.

Consolidated bio-saccharification (CBS) technology employs cellulosome-producing bacterial cells, rather than fungal cellulases, as biocatalysts for cost-effective production of lignocellulosic sugars. Extracellular ß-glucosidase (BGL) expression in the whole-cell arsenal is indispensable, due to severe cellobiose inhibition of the cellulosome. However, high-level BGL expression in Clostridium thermocellum is challenging, and the optimal BGL production level for efficient cellulose saccharification is currently unknown. Herein, we obtained new CBS biocatalysts by transforming BGL-expressing plasmids into C. thermocellum, which produced abundant BGL proteins and hydrolyzed cellulose effectively. The optimal ratio of extracellular BGL-to-cellulosome activity was determined to be in a range of 5.5 to 21.6. Despite the critical impact of BGL, both excessive BGL expression and its assembly on the cellulosome via type I cohesin-dockerin interaction led to reduced cellulosomal activity, which further confirmed the importance of coordinated BGL expression with the cellulosome. This study will further promote industrial CBS application in lignocellulose conversion.

Expression pattern and prognostic value of circadian clock genes in pancreatic adenocarcinoma.

Accumulating studies indicate that circadian clock genes are pivotal regulators of tumorigenesis and development of various cancers. Nevertheless, their implications in pancreatic adenocarcinoma (PAAD) remain poorly characterized. We investigated the expression pattern of circadian clock genes and evaluated their prognostic values in PAAD. Firstly, we systematically analyzed data from The Cancer Genome Atlas (TCGA) database pertaining to patient clinical information and gene expression data. We found that 19 of 20 circadian clock genes showed significantly different expression levels in comparisons between PAAD and normal tissues. In addition, 10 circadian clock genes with regression coefficients were selected to construct a new risk signature, which was then identified as an independent prognostic factor for PAAD. Mechanistically, circadian clock genes in PAAD may impact the basic state of cells and the composition of tumor-infiltrating immune cells, thus affecting disease prognosis. Finally, we construct a novel prognostic nomogram on the basis of histological nodes and risk score to precisely predict prognosis of patients with PAAD. In conclusion, our study uncovered the important role of circadian clock genes in PAAD and developed a risk signature as a promising prognostic biomarker for patients with PAAD.

FOXC1 up-regulates the expression of toll-like receptors in myocardial ischaemia.

Myocardial ischaemia (MI) remains a major cause of death and disability worldwide. Accumulating evidence suggests a significant role for innate immunity, in which the family of toll-like receptors (TLRs) acts as an essential player. We previously reported and reviewed the changes of Tlr expression in models of MI. However, the underlying mechanisms regulating Tlr expression in MI remain unclear. The present study first screened transcription factors (TFs) that potentially regulate Tlr gene transcription based on in silico analyses followed by experimental verification, using both in vivo and in vitro models. Forkhead box C1 (FOXC1) was identified as a putative TF, which was highly responsive to MI. Next, by focusing on two representative TLR subtypes, an intracellular subtype TLR3 and a cell-surface subtype TLR4, the regulation of FOXC1 on Tlr expression was investigated. The overexpression or knockdown of FoxC1 was observed to up- or down-regulate Tlr3/4 mRNA and protein levels, respectively. A dual-luciferase assay showed that FOXC1 trans-activated Tlr3/4 promoter, and a ChIP assay showed direct binding of FOXC1 to Tlr3/4 promoter. Last, a functional study of FOXC1 was performed, which revealed the pro-inflammatory effects of FOXC1 and its destructive effects on infarct size and heart function in a mouse model of MI. The present study for the first time identified FOXC1 as a novel regulator of Tlr expression and described its function in MI.

Alternative σI/anti-σI factors represent a unique form of bacterial σ/anti-σ complex.

The σ70 family alternative σI factors and their cognate anti-σI factors are widespread in Clostridia and Bacilli and play a role in heat stress response, virulence, and polysaccharide sensing. Multiple σI/anti-σI factors exist in some lignocellulolytic clostridial species, specifically for regulation of components of a multienzyme complex, termed the cellulosome. The σI and anti-σI factors are unique, because the C-terminal domain of σI (SigIC) and the N-terminal inhibitory domain of anti-σI (RsgIN) lack homology to known proteins. Here, we report structure and interaction studies of a pair of σI and anti-σI factors, SigI1 and RsgI1, from the cellulosome-producing bacterium, Clostridium thermocellum. In contrast to other known anti-σ factors that have N-terminal helical structures, RsgIN has a ß-barrel structure. Unlike other anti-σ factors that bind both σ2 and σ4 domains of the σ factors, RsgIN binds SigIC specifically. Structural analysis showed that SigIC contains a positively charged surface region that recognizes the promoter -35 region, and the synergistic interactions among multiple interfacial residues result in the specificity displayed by different σI/anti-σI pairs. We suggest that the σI/anti-σI factors represent a distinctive mode of σ/anti-σ complex formation, which provides the structural basis for understanding the molecular mechanism of the intricate σI/anti-σI system.

High-glucose Induced Mitochondrial Dynamics Disorder of Spinal Cord Neurons in Diabetic Rats and its Effect on Mitochondrial Spatial Distribution.

STUDY DESIGN: A randomized, double-blind, controlled trial. OBJECTIVE: Few studies have investigated the changes in mitochondrial dynamics in spinal cord neurons. Meanwhile, the distribution of mitochondria in axons remains unclear. In the present study, the investigators attempted to clarify these questions and focused in observing the changes in mitochondrial spatial distribution under a high-glucose environment. SUMMARY OF BACKGROUND DATA: Mitochondrial dynamics disorder is one of the main mechanisms that lead to nervous system diseases due to its adverse effects on mitochondrial morphology, function, and axon distribution. High-glucose stress can promote the increase in mitochondrial fission of various types of cells. METHODS: The lumbar spinal cord of type 1 diabetic Sprague-Dawley rats at 4 weeks was observed. VSC4.1 cells were cultured and divided into three groups: normal control group, high-glucose intervention group, and high-glucose intervention combined with mitochondrial fission inhibitor Mdivi-1 intervention group. Immunohistochemistry and immunofluorescence methods were used to detect the expression of mitochondrial marker VDAC-1 in the spinal cord. An electron microscope was used to observe the number, structure, and distribution of mitochondria. Western blot was used to detect VDAC-1, fusion protein MFN1, MFN2, and OPA1, and fission protein FIS1 and DRP1. Living cell mitochondrial staining was performed using MitoTracker. Laser confocal microscopy and an Olympus live cell workstation were used to observe the mitochondrial changes. RESULTS: The mitochondrial dynamics of spinal cord related neurons under an acute high-glucose environment were significantly unbalanced, including a reduction of fusion and increase of fission. Hence, mitochondrial fission has the absolute advantage. The total number of mitochondria in neuronal axons significantly decreased. CONCLUSION: Increased mitochondrial fission and abnormal distribution occurred in spinal cord related neurons in a high-glucose environment. Mdivi-1 could significantly improve these disorders of mitochondria in VSC4.1 cells. Mitochondrial division inhibitors had a positive significance on diabetic neuropathy. LEVEL OF EVIDENCE: N/A.

Firmicutes-enriched IS1447 represents a group of IS3-family insertion sequences exhibiting unique + 1 transcriptional slippage.

BACKGROUND: Bacterial insertion sequences (ISs) are ubiquitous mobile genetic elements that play important roles in genome plasticity, cell adaptability, and function evolution. ISs of various families and subgroups contain significantly diverse molecular features and functional mechanisms that are not fully understood. RESULTS: IS1447 is a member of the widespread IS3 family and was previously detected to have transposing activity in a typical thermophilic and cellulolytic microorganism Clostridium thermocellum. Phylogenetic analysis showed that IS1447-like elements are widely distributed in Firmicutes and possess unique features in the IS3 family. Therefore, IS1447 may represent a novel subgroup of the IS3 family. Unlike other well-known IS3 subgroups performing programmed - 1 translational frameshifting for the expression of the transposase, IS1447 exhibits transcriptional slippage in both the + 1 and - 1 directions, each with a frequency of ~ 16%, and only + 1 slippage results in full-length and functional transposase. The slippage-prone region of IS1447 contains a run of nine A nucleotides following a stem-loop structure in mRNA, but mutagenesis analysis indicated that seven of them are sufficient for the observed slippage. Western blot analysis indicated that IS1447 produces three types of transposases with alternative initiations. Furthermore, the IS1447-subgroup elements are abundant in the genomes of several cellulolytic bacteria. CONCLUSION: Our result indicated that IS1447 represents a new Firmicutes-enriched subgroup of the IS3 family. The characterization of the novel IS3-family member will enrich our understanding of the transposition behavior of IS elements and may provide insight into developing IS-based mutagenesis tools for thermophiles.

Inducing effects of cellulosic hydrolysate components of lignocellulose on cellulosome synthesis in Clostridium thermocellum.

Cellulosome is a highly efficient supramolecular machine for lignocellulose degradation, and its substrate-coupled regulation requires soluble transmembrane signals. However, the inducers for cellulosome synthesis and the inducing effect have not been clarified quantitatively. Values of cellulosome production capacity (CPC) and estimated specific activity (eSA) were calculated based on the primary scaffoldin ScaA to define the stimulating effects on the cellulosome synthesis in terms of quantity and quality respectively. The estimated cellulosome production of Clostridium thermocellum on glucose was at a low housekeeping level. Both Avicel and cellobiose increased CPCs of the cells instead of the eSAs of the cellulosome. The CPC of Avicel-grown cells was over 20-fold of that of glucose-grown cells, while both Avicel- and glucose-derived cellulosomes showed similar eSA. The CPC of cellobiose-grown cells was also over three times higher than glucose-grown cells, but the eSA of cellobiose-derived cellulosome was 16% lower than that of the glucose-derived cellulosome. Our results indicated that cello-oligosaccharides played the key roles in inducing the synthesis of the cellulosome, but non-cellulosic polysaccharides showed no inducing effects.

Lycium barbarum polysaccharide protects diabetic peripheral neuropathy by enhancing autophagy via mTOR/p70S6K inhibition in Streptozotocin-induced diabetic rats.

Lycium barbarum polysaccharide (LBP), the major active component of Lycium barbarum, has been found to be effective in the management of some diabetic complications. We evaluated the protective effect of LBP in diabetic peripheral neuropathy (DPN) and explored the possible mechanisms. We found that LBP mildly decreased blood glucose levels and partially rescued allodynia and hyperalgesia in the diabetes mellitus (DM) rats. For the electrophysiological function of the sciatic nerve, the decrease in sensory nerve conduction velocity (SNCV) and sensory nerve action potential (SNAP) amplitudes in DM rats were partially rescued. Moreover, DM-induced structural damage to the nerve fiber myelination showed great improvement by 12 weeks of LBP treatment. The decreased expression of the myelin-related proteins, myelin protein zero (P0) and myelin basic protein (MBP), in the DM sciatic nerve was also markedly rescued after 12 weeks of LBP treatment. Furthermore, the possible role of mammalian target of rapamycin (mTOR)-mediated autophagy during these protective processes was examined. The expression of microtubule-associated protein light chain 3-II(LC3-II) and Beclin1 in the sciatic nerve was significantly decreased while the expression of P62 increased in DM rats, demonstrating an decreased activation of autophagy. As expected, the LC3-II and Beclin1 protein levels were markedly increased, and P62 was markedly decreased after LBP treatment. The expression of mTOR, p-mTOR, p70 ribosomal protein S6 kinase (p70S6K) and p-p70S6K in the DM group were markedly increased, while all of these proteins decreased in LBP group. These results demonstrate that LBP exerts protective effects on DPN, which is likely to be mediated through the induction of autophagy by inhibiting the activation of the mTOR/p70S6K pathways.

Dimethylation of Histone 3 Lysine 9 is sensitive to the epileptic activity, and affects the transcriptional regulation of the potassium channel Kcnj10 gene in epileptic rats.

Potassium channels can be affected by epileptic seizures and serve a crucial role in the pathophysiology of epilepsy. Dimethylation of histone 3 lysine 9 (H3K9me2) and its enzyme euchromatic histone­lysine N­methyltransferase 2 (G9a) are the major epigenetic modulators and are associated with gene silencing. Insight into whether H3K9me2 and G9a can respond to epileptic seizures and regulate expression of genes encoding potassium channels is the main purpose of the present study. A total of 16 subtypes of potassium channel genes in pilocarpine­modelled epileptic rats were screened by reverse transcription­quantitative polymerase chain reaction, and it was determined that the expression ATP­sensitive inward rectifier potassium channel 10 (Kcnj10) increased in hippocampus and insular cortex, while the expression of most of the other subtypes decreased. The total level of H3K9me2 decreased in the model group compared with the control. The Kcnj10 gene encoding the Kir4.1 channel was selected to analyse changes in H3K9me2 in the promoter region by the chromatin immuno­precipitation method. Anti­H3K9me2 and anti­G9a antibodies were used to identify the modified DNAs. Five primers were designed across the promoter region of the Kcnj10 gene. In epileptic hippocampi, the relative abundance of H3K9me2 and G9a in the promoter region of Kcnj10 decreased markedly. Removal of the H3K9me2 repressive mark resulted in decreased transcriptional inhibition of the Kcnj10 gene and therefore increased its expression. In the cultured C6 cells, specific inhibition of the enzymatic activity of G9a by 2­(Hexahydro­4­methyl­1H­1,4­diazepin­1­yl)­6,7­di­ methoxy­N­(1­(phenyl­methyl)­4­piperidinyl)­4­quinazolinamine tri­hydrochloride hydrate (bix01294) resulted in upregulation of the expression of Kir4.1 proteins. The present study demonstrated that H3K9me2 and G9a are sensitive to epileptic seizure activity during the acute phase of epilepsy and can affect the transcriptional regulation of the Kcnj10 channel.

TLR3 contributes to persistent autophagy and heart failure in mice after myocardial infarction.

Toll-like receptors (TLRs) are essential immunoreceptors involved in host defence against invading microbes. Recent studies indicate that certain TLRs activate immunological autophagy to eliminate microbes. It remains unknown whether TLRs regulate autophagy to play a role in the heart. This study examined this question. The activation of TLR3 in cultured cardiomyocytes was observed to increase protein levels of autophagic components, including LC3-II, a specific marker for autophagy induction, and p62/SQSTM1, an autophagy receptor normally degraded in the final step of autophagy. The results of transfection with a tandem mRFP-GFP-LC3 adenovirus and use of an autophagic flux inhibitor chloroquine both suggested that TLR3 in cardiomyocytes promotes autophagy induction without affecting autophagic flux. Gene-knockdown experiments showed that the TRIF-dependent pathway mediated the autophagic effect of TLR3. In the mouse model of chronic myocardial infarction, persistent autophagy was observed, concomitant with up-regulated TLR3 expression and increased TLR3-Trif signalling. Germline knockout (KO) of TLR3 inhibited autophagy, reduced infarct size, attenuated heart failure and improved survival. These protective effects were abolished by in vivo administration of an autophagy inducer rapamycin. Similar to the results obtained in cultured cardiomyocytes, TLR3-KO did not prevent autophagic flux in mouse heart. Additionally, this study failed to detect the involvement of inflammation in TLR3-KO-derived protection, as wild-type and TLR3-KO hearts were comparable in inflammatory activity. It is concluded that up-regulated TLR3 expression and signalling contributes to persistent autophagy following MI, which promotes heart failure and lethality.

HSPB8 Promotes the Fusion of Autophagosome and Lysosome during Autophagy in Diabetic Neurons.

Although autophagy has been proposed to play an emerging role in diabetic neuropathy, autophagy and its possible role remains unclear. Moreover, only few studies about diabetes have explored the autophagy mediated by heat shock protein beta-8 (HSPB8) and Bcl-2 associated athanogene 3 (BAG3). In the present study, we examined the autophagy induced by high glucose levels in an in vivo rat model of diabetes induced by streptozotocin (STZ) and an in vitro model of retinal ganglion cell-5 (RGC5) cells under high glucose conditions. In the spinal cord tissues of the STZ-induced diabetic rats, the levels of light chain 3 (LC3) and Beclin-1-marked autophagy rose with increasing HSPB8 and BAG3 levels. By confocal immunofluorescence, HSPB8 and LC3 were observed to be co-localized in the spinal cord tissues. In the RGC5 cells, high-glucose stimulation upregulated the expression of LC3-Ⅱ, Beclin-1, and HSPB8 in a dose-dependent manner. When the RGC5 cells were subjected to high-glucose conditions, HSPB8 overexpression, along with upregulated LC3-Ⅱ and Beclin-1 expression, increased the autophagic rate, whereas siRNA-silenced HSPB8 decreased the autophagic rate. Furthermore, in GFP-mRFP-LC3 probe experiments, HSPB8 overexpression promoted autophagosome-lysosome fusion, whereas HSPB8 silencing disrupted this process. In the cells treated with HSPB8 and siRNA, the fusion was impaired, as indicated by the elevated p62 expression. HSPB8 overexpression can partly rescue the blocking of the autophagy flux with chloroquine through the reduction of p62 expression level. Our study demonstrated that HSPB8 is involved in the high glucose-induced autophagy under the in vivo and in vitro conditions and critically participated in the autophagosome-lysosome fusion during the autophagy flux.

MiR-126 Suppresses the Glucose-Stimulated Proliferation via IRS-2 in INS-1 ß Cells.

BACKGROUND: Increasing evidence suggests that miR-126 participates in the glucose homeostasis through its target molecules. Although bioinformatics analysis predicts that miR-126 can bind with the insulin receptor substrate-2(IRS-2) mRNA at the "seed sequence", but there are still no definitely reports to support it. In this study, we provided evidences that IRS-2 was one of the target genes of miR-126. And miR-126 has a proliferation inhibiting effects in INS-1 ß cells, mainly through the suppression of IRS-2. METHODS: The 3'-UTR of IRS-2 regulated by miR-126 was analyzed by the luciferase assay and western blot. Furthermore, proliferation of INS-1 ß cells stimulated by glucose was tested, and the association between IRS-2 and miR-126 were analyzed. RESULTS: We found that mutation of only three of the 6 "seed sequences" can eliminate the inhibition effect of miR-126. In INS-1 ß cells, administration of miR-126 suppresses the proliferation, together with the unbalanced down-regulation of IRS-2 and IRS-1. Over-expression of IRS-2 can reverse the proliferation effect of miR-126, while not of IRS-1. These results suggested that miR-126 inhibited the ß-cell proliferation via the inhibition of IRS-2 instead of IRS-1.Additionally, we also found that high glucose and insulin could stimulate the rapid production of endogenous miR-126 within 6 hours, together with the short term suppression of IRS-1 and IRS-2 expression, and intensify the unbalanced expression of IRS-1 and IRS-2. CONCLUSIONS: IRS-2 was one of the targets of miR-126. MiR-126 inhibited the ß-cell proliferation through IRS-2 instead of IRS-1. MiR-126 may take part in the glucose homeostasis both through its target IRS-2 and IRS-1. The unbalance between IRS-1 and IRS-2 caused by miR-126 may play an important role in type 2 diabetes.

Centrally acting drug moxonidine decreases reactive oxygen species via inactivation of the phosphoinositide-3 kinase signaling in the rostral ventrolateral medulla in hypertensive rats.

OBJECTIVE: Centrally acting antihypertensive action of moxonidine is a result of activation of Imidazoline-1 receptor (I1R) in the rostral ventrolateral medulla (RVLM). Hypertension shows an increase in reactive oxygen species (ROS) in the RVLM. The present objective was to determine the phosphoinositide-3 kinase (PI3K) signaling pathway involved in the effect of moxonidine on ROS generation in the RVLM of spontaneously hypertensive rat (SHR). METHODS: Wistar-Kyoto rats and SHR received intracisternal infusion (2 weeks) of tested agents which were subjected to subsequent experiments. In-situ ROS in the RVLM was evaluated by the oxidative fluorescence dye. Western blot and PCR analysis were performed to detect the expression levels of PI3K signaling pathway. Lentivirus was injected bilaterally into the RVLM for silencing PI3K signaling. RESULTS: ROS production in the RVLM was dose-dependently reduced in SHRs treated with infusion of moxonidine (20 nmol/day), which was prevented by the I1R antagonist efaroxan but not by the α2-adrenoceptor antagonist yohimbine. Moxonidine pretreatment significantly blunted cardiovascular sensitivity to injection of tempol (5 nmol) or angiotensin II (10 pmol) into the RVLM in SHR. Expression levels of PI3K/Akt, nuclear factor kappa-B (NFκB), NADPHase (NOX4), and angiotensin type I receptor (AT1R) in the RVLM were markedly decreased in SHR treated with moxonidine. Infection of lentivirus containing PI3K shRNA in the RVLM effectively prevented effects of moxonidine on cardiovascular activity and expression levels of Akt, NFκB, NOX4, and AT1R. CONCLUSION: The centrally antihypertensive drug moxonidine decreases ROS production in the RVLM through inactivation of the PI3K/Akt signaling pathway in hypertension.

Up-regulated TLR4 in cardiomyocytes exacerbates heart failure after long-term myocardial infarction.

It remains unclear whether and how cardiomyocytes contribute to the inflammation in chronic heart failure (CHF). We recently reviewed the capacity of cardiomyocytes to initiate inflammation, by means of expressing certain immune receptors such as toll-like receptors (TLRs) that respond to pathogen- and damage-associated molecular patterns (PAMP and DAMP). Previous studies observed TLR4-mediated inflammation within days of myocardial infarction (MI). This study examined TLR4 expression and function in cardiomyocytes of failing hearts after 4 weeks of MI in rats. The increases of TLR4 mRNA and proteins, as well as inflammatory cytokine production, were observed in both the infarct and remote myocardium. Enhanced immunostaining for TLR4 was observed in cardiomyocytes but not infiltrating leucocytes. The injection of lentivirus shRNA against TLR4 into the infarcted heart decreased inflammatory cytokine production and improved heart function in vivo. Accordingly, in cardiomyocytes isolated from CHF hearts, increases of TLR4 mRNA and proteins were detected. More robust binding of TLR4 with lipopolysaccharide (LPS), a PAMP ligand for TLR4, and heat shock protein 60 (HSP60), a DAMP ligand for TLR4, was observed in CHF cardiomyocytes under a confocal microscope. The maximum binding capacity (Bmax ) of TLR4 was increased for LPS and HSP60, whereas the binding affinity (Kd) was not significantly changed. Furthermore, both LPS and HSP60 induced more robust production of inflammatory cytokines in CHF cardiomyocytes, which was reduced by TLR4-blocking antibodies. We conclude that the expression, ligand-binding capacity and pro-inflammatory function of cardiomyocyte TLR4 are up-regulated after long-term MI, which promote inflammation and exacerbate heart failure.

Overexpression of angiotensin-converting enzyme 2 attenuates tonically active glutamatergic input to the rostral ventrolateral medulla in hypertensive rats.

The rostral ventrolateral medulla (RVLM) plays a key role in cardiovascular regulation. It has been reported that tonically active glutamatergic input to the RVLM is increased in hypertensive rats, whereas angiotensin-converting enzyme 2 (ACE2) in the brain has been suggested to be beneficial to hypertension. This study was designed to determine the effect of ACE2 gene transfer into the RVLM on tonically active glutamatergic input in spontaneously hypertensive rats (SHRs). Lentiviral particles containing enhanced green fluorescent protein (lenti-GFP) or ACE2 (lenti-ACE2) were injected bilaterally into the RVLM. Both protein expression and activity of ACE2 in the RVLM were increased in SHRs after overexpression of ACE2. A significant reduction in blood pressure and heart rate in SHRs was observed 6 wk after lenti-ACE2 injected into the RVLM. The concentration of glutamate in microdialysis fluid from the RVLM was significantly reduced by an average of 61% in SHRs with lenti-ACE2 compared with lenti-GFP. ACE2 overexpression significantly attenuated the decrease in blood pressure and renal sympathetic nerve activity evoked by bilateral injection of the glutamate receptor antagonist kynurenic acid (2.7 nmol in 100 nl) into the RVLM in SHRs. Therefore, we suggest that ACE2 overexpression in the RVLM attenuates the enhanced tonically active glutamatergic input in SHRs, which may be an important mechanism underlying the beneficial effect of central ACE2 to hypertension.

Finite element analysis on mechanical responses of human torso with body armor to non penetrating ballistic impact / 医用生物力学

ObjectiveTo develop a finite element computational model of the torso for the numerical simulation of mechanical responses of human torso to non-penetrating ballistic impact. MethodsBased on the CT data of a Chinese adult man, the finite element model of human torso was created by using the medical image processing software Mimics and the finite element pre-processing software HyperMesh. The pressure and acceleration response of the human torso outfitted with soft body armor to the ballistic impact from 9 mm ammunition at a velocity of 360 m/s was calculated numerically by the explicit finite element code LS-DYNA. ResultsThe finite element model of human torso including thoracic skeletal structure, organs, mediastinum and muscle/skin was established. The pressure response of heart, lung, liver and stomach, as well as the acceleration response of sternum were obtained by numerical calculation. It was found that the peak pressure and its time phase were dependent on the distance between the impact point and the measured point wherever in various organs or different position of an organ. Conclusions The finite element computational model of human torso outfitted with soft body armor is available for the simulation of human response to non-penetrating ballistic impact, and the simulated response can be used as evidence for the investigation on mechanism and protection of behind armor blunt frauma.

[Study on the interactions of Eu(III) complex of O-(thioxanthone-[2]-yl)-oxyacetic acid with DNA].

The interaction of the Eu(III) complex of O-(thioxanthone-[2]-yl)-oxyacetic acid and calf thymus DNA was studied using fluorimetric, UV-Vis and CD(circular dichroism) methods. It was found that the ultraviolet absorption intensity of Eu(III) complex of O-(thioxanthone-[2]-yl)-oxyacetic acid decreased as the concentration of DNA increased under the physiological condition of pH 7.10, and the compound remarkably influenced the negative peak in CD spectra of DNA when Eu(III) complex of O-(thioxanthone-[2]-yl)-oxyacetic acid interacted with DNA. The emission intensity of the Eu(III) complex evidently increased in the presence of DNA. The emission intensity of the DNA-EB system decreased as the concentration of the complex increasesd. And the presence of EB also led to the decrease in the emission intensity of the DNA-complex system. These changes observed here are often characteristic of intercalation. The above results strongly suggest that the complex can bind to DNA mainly by intercalation.