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author:("Guo, zhikong")
1.  Effect of pollen typhae on inhibiting autophagy in spinal cord injury of rats and its mechanisms 
Purpose: To investigate the effects and mechanism of pollen typhae on spinal cord injury (SCI) in rats. Methods: The SCI model was built and animals were randomly divided into three groups according to different concentrations of pollen typhae. Protein, mRNA, and fluorescence expression levels of light-chain-3 (LC-3) and Beclin-1 were determined by western blotting (WB), real-time PCR and immunofluorescence, along as Akt and mammalian target of rapamycin (mROT) by WB. The demyelination area and integrated optical density (IOD) were analyzed by luxol fast blue (LFB) and Nissl staining, respectively; Behavioral assessments were assessed by Basso Beattie Bresnahan (BBB) scale. Results: Protein, mRNA, and fluorescence expression levels of LC-3 and Beclin-1 were significantly increased after SCI, while were obviously decreased by administration of pollen typhae, along with protein level of Akt and mROT. The demyelination area was significantly reduced, while IOD and BBB were significantly increased compared with the model group. Conclusion: Autophagic activity increased in damaged neural tissue after SCI, and pollen typhae have certain therapeutic effect on SCI, the higher concentration of pollen typhae, the more effective. Besides, pollen typhae also provided neuroprotective effect and improved locomotor function. The effects may be produced by blockade of Akt/mTOR pathway.
PMCID: PMC4440053  PMID: 26045744
Spinal cord injury; pollen typhae; Beclin-1; LC-3; autophagy; Akt/mTOR
2.  Collagen-Like Proteins (ClpA, ClpB, ClpC, and ClpD) Are Required for Biofilm Formation and Adhesion to Plant Roots by Bacillus amyloliquefaciens FZB42 
PLoS ONE  2015;10(2):e0117414.
The genes of collagen-like proteins (CLPs) have been identified in a broad range of bacteria, including some human pathogens. They are important for biofilm formation and bacterial adhesion to host cells in some human pathogenic bacteria, including several Bacillus spp. strains. Interestingly, some bacterial CLP-encoding genes (clps) have also been found in non-human pathogenic strains such as B. cereus and B. amyloliquefaciens, which are types of plant-growth promoting rhizobacteria (PGPR). In this study, we investigated a putative cluster of clps in B. amyloliquefaciens strain FZB42 and a collagen-related structural motif containing glycine-X-threonine repeats was found in the genes RBAM_007740, RBAM_007750, RBAM_007760, and RBAM_007770. Interestingly, biofilm formation was disrupted when these genes were inactivated separately. Scanning electron microscopy and hydrophobicity value detection were used to assess the bacterial cell shape morphology and cell surface architecture of clps mutant cells. The results showed that the CLPs appeared to have roles in bacterial autoaggregation, as well as adherence to the surface of abiotic materials and the roots of Arabidopsis thaliana. Thus, we suggest that the CLPs located in the outer layer of the bacterial cell (including the cell wall, outer membrane, flagella, or other associated structures) play important roles in biofilm formation and bacteria-plant interactions. This is the first study to analyze the function of a collagen-like motif-containing protein in a PGPR bacterium. Knocking out each clp gene produced distinctive morphological phenotypes, which demonstrated that each product may play specific roles in biofilm formation. Our in silico analysis suggested that these four tandemly ranked genes might not belong to an operon, but further studies are required at the molecular level to test this hypothesis. These results provide insights into the functions of clps during interactions between bacteria and plants.
PMCID: PMC4319854  PMID: 25658640
3.  Ultrasound Guidance for Radial Artery Catheterization: An Updated Meta-Analysis of Randomized Controlled Trials 
PLoS ONE  2014;9(11):e111527.
Since a previous meta-analysis reported that ultrasound guidance was associated with a higher first-attempt success rate in catheterization of the radial artery, a number of randomized controlled trials (RCTs) have reported inconsistent results. The aim of the present study is to conduct an updated meta-analysis to clarify the role of ultrasound guidance for radial artery catheterization.
A systematic literature search of PubMed, Embase, and Cochrane Central Register of Controlled Trials was conducted using specific search terms. Eligible studies were RCTs that compared ultrasound guidance with traditional palpation for radial artery catheterization. The Mantel-Haenszel method using the random effects model was adopted in this meta-analysis.
Seven RCTs with 482 patients were included. Compared with traditional palpation, ultrasound guidance significantly increased the first-attempt success rate of radial artery catheterization (RR 1.51, 95% CI 1.07–2.14, P = 0.02). Subgroup analyses suggested that the superiority of ultrasound guidance for radial artery catheterization was significant when the technique was operated by experienced users, performed in small children and infants, and on elective procedures in the operating room. In addition, ultrasound guidance significantly reduced mean-attempts to success (WMD −1.13, 95% CI −1.58 to −0.69, P<0.00001), mean-time to success (WMD −74.77s, 95% CI −137.89s to −11.64s, P = 0.02), and the occurrence of hematoma (RR 0.17, 95% CI 0.07–0.41, P = 0.0001).
The present meta-analysis suggests a clear benefit from ultrasound guidance for radial artery catheterization compared with the traditional palpation. Preliminary training and familiarization with the ultrasound-guided technique is needed before applying it for radial artery catheterization, especially for inexperienced operators.
PMCID: PMC4222952  PMID: 25375152
4.  Neuroprotective effects of PPAR-γ agonist rosiglitazone in N171-82Q mouse model of Huntington’s disease 
Journal of neurochemistry  2013;125(3):410-419.
Huntington’s disease (HD) is a devastating genetic neurodegenerative disease caused by CAG trinucleotide expansion in the exon-1 region of the huntingtin gene. Currently, no cure is available. It is becoming increasingly apparent that mutant HTT impairs metabolic homeostasis and causes transcriptional dysregulation. The peroxisome proliferator-activated receptor gamma (PPAR-γ) is a transcriptional factor that plays a key role in regulating genes involved in energy metabolism; recent studies demonstrated that PPAR-γ activation prevented mitochondrial depolarization in cells expressing mutant HTT and attenuated neurodegeneration in various models of neurodegenerative diseases. PPAR-γ-coactivator 1α (PGC-1 α) transcription activity is also impaired by mutant HTT. We now report that the PPAR-γ agonist, rosiglitazone (RSG), significantly attenuated mutant HTT-induced toxicity in striatal cells and that the protective effect of RSG is mediated by activation of PPAR-γ. Moreover, chronic administration of RSG (10 mg/kg/d, i.p) significantly improved motor function and attenuated hyperglycemia in N171-82Q HD mice. RSG administration rescued BDNF deficiency in the cerebral cortex, and prevented loss of orexin-A-immunopositive neurons in the hypothalamus of N171-82Q HD mice. RSG also prevented PGC-1α reduction and increased Sirt6 protein levels in HD mouse brain. Our results suggest that modifying the PPAR-γ pathway plays a beneficial role in rescuing motor function as well as glucose metabolic abnormalities in HD.
PMCID: PMC3642978  PMID: 23373812
PPAR-γ; huntingtin; glucose metabolism; PGC-1α; Sirt6; BDNF
5.  Epidemiological Study and Control Trial of Taeniid Cestode Infection in Farm Dogs in Qinghai Province, China 
An epidemiological study and control trial were conducted to assess taeniid infection in farm dogs in Qinghai Province, China. To improve egg detection by fecal examination, a deworming step with praziquantel was incorporated into the sampling methodology. As a result, a marked increase in the number of egg-positive samples was observed in samples collected at 24 hr after deworming. Then, the fecal examination and barcoding of egg DNA were performed to assess the prevalence of taeniid species in dogs from Xinghai, Haiyan, Gangcha and Chengduo counties. Analysis of 277 dog feces revealed that taeniid cestodes, including Taenia spp. and Echinococcus granulosus, were highly prevalent in Xinghai (34.4%), but eggs were not found in Haiyan where a control trial on canine echinococcosis had been conducted 20 years previously. A control trial involving the administration of 5–10 mg/kg praziquantel to 90 farm dogs at 45-day intervals was conducted in Xinghai. The prevalence of taeniid cestodes in the dogs was reduced to 9.6% and 4.9% after one and two years, respectively, indicating that some dogs were not administered praziquantel properly. A questionnaire survey of farmers in Xinghai and Haiyan revealed that most farmers in Xinghai were not familiar with echinococcosis or the transmission route of the disease, while most farmers in Haiyan had a more thorough understanding of the disease. The findings implied that a program for educating local farmers would be important for efficiently controlling canine taeniid infection in the region.
PMCID: PMC4013366  PMID: 24257329
canine; China; control; Echinococcus; taeniid cestodes
6.  An Epidemiological Study of Hypoderma Infection and Control Using Ivermectin in Yaks in Qinghai Province, China 
The prevalence of Hypoderma spp. in yaks grazed in the east of Qinghai province was investigated in 2008. In this area, the prevalence in young yaks (1- to 3-year-old) was very high at 82.2–98.7%, whilst in adult yaks (4-year-old and older), the prevalence was 42.4–50.6%. The seasonal development and migration pattern of Hypoderma larvae in yak bodies was found to be similar for different locations in this area. The numbers of first, second and third instar larvae detected in yak bodies peaked in October, December and March, respectively. Different doses of ivermectin (125 to 500 µg/kg body weight) almost completely dewormed the larvae from yaks, suggesting that using a quarter of the prescribed dose (500 µg/kg body weight) was effective. In October of each year between 2009 and 2012, ivermectin (125 µg/kg body weight) was administered to a total of 562,995 yaks grazed in four counties in Qinghai province, and the pevalence of Hypoderma larval infection in yaks was reduced to 0.5–1.0%.
PMCID: PMC3982821  PMID: 24107486
China; Hypoderma; ivermectin; Qinghai; yak
7.  Identification of a Hotdog Fold Thioesterase Involved in the Biosynthesis of Menaquinone in Escherichia coli 
Journal of Bacteriology  2013;195(12):2768-2775.
Escherichia coli is used as a model organism for elucidation of menaquinone biosynthesis, for which a hydrolytic step from 1,4-dihydroxy-2-naphthoyl-coenzyme A (DHNA-CoA) to 1,4-dihydroxy-2-naphthoate is still unaccounted for. Recently, a hotdog fold thioesterase has been shown to catalyze this conversion in phylloquinone biosynthesis, suggesting that its closest homolog, YbgC in Escherichia coli, may be the DHNA-CoA thioesterase in menaquinone biosynthesis. However, this possibility is excluded by the involvement of YbgC in the Tol-Pal system and its complete lack of hydrolytic activity toward DHNA-CoA. To identify the hydrolytic enzyme, we have performed an activity-based screen of all nine Escherichia coli hotdog fold thioesterases and found that YdiI possesses a high level of hydrolytic activity toward DHNA-CoA, with high substrate specificity, and that another thioesterase, EntH, from siderophore biosynthesis exhibits a moderate, much lower DHNA-CoA thioesterase activity. Deletion of the ydiI gene from the bacterial genome results in a significant decrease in menaquinone production, which is little affected in ΔybgC and ΔentH mutants. These results support the notion that YdiI is the DHNA-CoA thioesterase involved in the biosynthesis of menaquinone in the model bacterium.
PMCID: PMC3697248  PMID: 23564174
8.  Survey on Helminths in the Small Intestine of Wild Foxes in Qinghai, China 
The intestinal helminth fauna of Tibetan sand foxes (Vulpes ferrilata) and red foxes (Vulpes vulpes) inhabiting in Qinghai, China, was evaluated by conducting necropsy of hunted foxes and fecal egg examination of field-collected feces. In northeast and south Qinghai, 36 foxes were necropsied, and the species of foxes and the parasites detected were identified by the DNA barcoding. In 27 red foxes and 9 Tibetan sand foxes examined, Mesocestoides litteratus (total prevalence: 64%), Toxascaris leonina (50%), Taenia pisiformis (8%) and Taenia crassiceps (8%) were found in both species of foxes. Echinococcus shiquicus (8%) and Taenia multiceps (6%) were found only in Tibetan sand foxes. Echinococcus multilocularis (3%) and Alaria alata (8%) were found only in red foxes. In the fecal egg examination of the rectal feces, 100% of taeniid cestodes, 73% of Toxascaris and 27% of Mesocestoides worm-positive samples showed egg-positive, indicating that coprological survey for parasite eggs could only provide partial information of intestinal parasite fauna. For field-collected feces, molecular identification of feces origins and fecal egg examination were performed. In 15 Tibetan sand fox and 30 red fox feces, we found E. multilocularis eggs in one feces of Tibetan sand fox. The present study indicated that the upper intestinal helminth fauna of the two fox species in Qinghai does not differ significantly and both species would play an important role in the maintenance of taeniid cestodes.
PMCID: PMC3942932  PMID: 23749034
China; helminth fauna; Qinghai; red foxes; Tibetan sand foxes
9.  Striatal neuronal loss correlates with clinical motor impairment in Huntington’s disease 
Huntington disease is characterized clinically by chorea, motor impairment, psychiatric manifestations and dementia. Atrophy of the striatum is the neuropathological hallmark of Huntington disease and previous studies have suggested that striatal atrophy correlates more closely with motor impairment than with chorea. Motor impairment, as measured by motor impairment score, correlates with functional disability in Huntington patients, but chorea does not. In this study, we investigate the relation between neuronal loss and these motor features.
We conducted neuropathological and stereologic assessments of neurons in putamen and subthalamic nuclei in Huntington patients and age-matched controls. In putamen, we estimated the total number and volume of medium spiny neurons labeled with dopamine- and cAMP-regulated phosphoprotein 32 kDa (DARPP32). In subthalamic nuclei, we estimated the total number of neurons on Hematoxylin/Eosin -Luxol/Fast Blue stains.
In putamen of Huntington disease, immunohistochemistry showed DARPP 32 neuronal atrophy with extensive disruption of neurites and neuropil; stereologic studies found significant decreases in both the number and size of DARPP32 neurons; we also detected a significant reduction of overall putamen volume in Huntington patients compared with controls. In subthalamic nuclei, there was a mild but significant neuronal loss in Huntington group. The loss of neurons in putamen and subthalamic nuclei and the putaminal atrophy were significantly correlated with the severity of motor impairment, but not with chorea.
Our findings suggest that neuronal loss and atrophy in striatum and neuronal loss in subthalamic nuclei contribute specifically to the motor impairment of Huntington, but not to chorea.
PMCID: PMC3455126  PMID: 22975850
Putamen; subthalamic nucleus; medium spiny neurons; DARPP32; stereology
10.  Crystal Structures of E. coli Native MenH and Two Active Site Mutants 
PLoS ONE  2013;8(4):e61325.
Recent revision of the biosynthetic pathway for menaquinone has led to the discovery of a previously unrecognized enzyme 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase, also known as MenH. This enzyme has an α/β hydrolase fold with a catalytic triad comprising Ser86, His232, and Asp210. Mutational studies identified a number of conserved residues of importance to activity, and modeling further implicated the side chains of Tyr85 and Trp147 in formation of a non-standard oxyanion hole. We have solved the structure of E. coli MenH (EcMenH) at 2.75 Å resolution, together with the structures of the active site mutant proteins Tyr85Phe and Arg124Ala, both at 2.5 Å resolution. EcMenH has the predicted α/β hydrolase fold with its core α/β domain capped by a helical lid. The active site, a long groove beneath the cap, contains a number of conserved basic residues and is found to bind exogeneous anions, modeled as sulfate and chloride, in all three crystal structures. Docking studies with the MenH substrate and a transition state model indicate that the bound anions mark the binding sites for anionic groups on the substrate. The docking studies, and careful consideration of the active site geometry, further suggest that the oxyanion hole is of a conventional nature, involving peptide NH groups, rather than the proposed site involving Tyr85 and Trp147. This is in accord with conclusions from the structure of S. aureus MenH. Comparisons with the latter do, however, indicate differences in the periphery of the active site that could be of relevance to selective inhibition of MenH enzymes.
PMCID: PMC3630204  PMID: 23637813
11.  Structure and Reactivity of Bacillus subtilis MenD Catalyzing the First Committed Step in Menaquinone Biosynthesis 
Journal of Molecular Biology  2010;401(2):253-264.
The first committed step in the classical biosynthetic route to menaquinone (vitamin K2) is a Stetter-like conjugate addition of α-ketoglutarate with isochorismate. This reaction is catalyzed by the thiamine diphosphate and metal-ion-dependent 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexadiene-1-carboxylate synthase (MenD). The medium-resolution (2.35 Å) crystal structure of Bacillus subtilis MenD with cofactor and Mn2+ has been determined. Based on structure–sequence comparisons and modeling, a two-stage mechanism that is primarily driven by the chemical properties of the cofactor is proposed. Hypotheses for the molecular determinants of substrate recognition were formulated. Five basic residues (Arg32, Arg106, Arg409, Arg428, and Lys299) are postulated to interact with carboxylate and hydroxyl groups to align substrates for catalysis in combination with a cluster of non-polar residues (Ile489, Phe490, and Leu493) on one side of the active site. The powerful combination of site-directed mutagenesis, where each of the eight residues is replaced by alanine, and steady-state kinetic measurements has been exploited to address these hypotheses. Arg409 plays a significant role in binding both substrates while Arg428 contributes mainly to binding of α-ketoglutarate. Arg32 and in particular Arg106 are critical for recognition of isochorismate. Mutagenesis of Phe490 and Ile489 has the most profound influence on catalytic efficiency, indicating that these two residues are important for binding of isochorismate and for stabilizing the cofactor position. These data allow for a detailed description of the structure–reactivity relationship that governs MenD function and refinement of the model for the catalytic intermediate that supports the Stetter-like conjugate addition.
PMCID: PMC2914249  PMID: 20600129
CoA, coenzyme A; PDB, Protein Data Bank; SAD, single-wavelength anomalous diffraction; SEPHCHC, 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexadiene-1-carboxylate; SeMet, selenomethionine; ThDP, thiamine diphosphate; PEG, polyethylene glycol; crystal structure; enzyme mechanism; menaquinone biosynthesis; thiamine diphosphate cofactor
12.  Fluid-structure Interaction within a Layered Aortic Arch Model 
Journal of Biological Physics  2006;32(5):435-454.
The response of wall stress to the elasticity of each layer in the aorta wall was investigated to understand the role of the different elastic properties of layers in the aortic dissection. The complex mechanical interaction between blood flow and wall dynamics in a three-dimensional arch model of an aorta was studied by means of computational coupled fluid-structure interaction analysis. The results show that stresses in the media layer are highest in three layers and that shear stress is concentrated in the media layer near to the adventitia layer. Hence, the difference in the elastic properties of the layers could be responsible for the pathological state in which a tear splits across the tunica media to near to the tunica adventitia and the dissection spreads along the laminar planes of the media layer where it is near the adventitia layer.
PMCID: PMC2651537  PMID: 19669449
aortic arch; aortic dissection; layered wall; wall stresses; fluid-structure interaction
13.  Prophylactic Treatment with Paroxetine Ameliorates Behavioral Deficits and Retards the Development of Amyloid and Tau Pathologies in 3xTgAD Mice 
Experimental neurology  2007;205(1):166-176.
A history of depression is a risk factor for Alzheimer’s disease (AD), suggesting the possibility that antidepressants administered prophylactically might retard the disease process and preserve cognitive function. Here we report that pre-symptomatic treatment with the antidepressant paroxetine attenuates the disease process and improves cognitive performance in the 3xTgAD mouse model of AD. Five month-old male and female 3xTgAD and non-transgenic mice were administered either paroxetine or saline daily for 5 months. Open-field activity was tested in 7 month-old mice and performance in passive avoidance and Morris swim tasks were evaluated at 10 months. 3xTgAD mice exhibited reduced exploratory activity, increased transfer latency in the passive avoidance test and impaired performance in the Morris spatial navigation task compared to nontransgenic control mice. Paroxetine treatment ameliorated the spatial navigation deficit in 3xTgAD male and female mice, without affecting swim speed or distance traveled, suggesting a preservation of cognitive function. Levels of amyloid beta-peptide (Aβ) and numbers of Aβ immunoreactive neurons were significantly reduced in the hippocampus of male and female paroxetine-treated 3xTgAD mice compared to saline-treated 3xTgAD mice. Female 3xTgAD mice exhibited significantly less tau pathology in the hippocampus and amygdala compared to male 3xTgAD mice, and paroxetine lessened tau pathology in male 3xTgAD mice. The ability of a safe and effective antidepressant to suppress neuropathological changes and improve cognitive performance in a mouse model, suggests that such drugs administered prophylactically might retard the development of AD in humans.
PMCID: PMC1979096  PMID: 17368447
14.  B-Cell Responses in Patients Who Have Recovered from Severe Acute Respiratory Syndrome Target a Dominant Site in the S2 Domain of the Surface Spike Glycoprotein 
Journal of Virology  2005;79(6):3401-3408.
Severe acute respiratory syndrome (SARS) is a recently emerged infectious disease caused by a novel strain of coronavirus. Examination of the immune responses of patients who have recovered from SARS should provide important information for design of a safe and effective vaccine. We determined the continuous viral epitopes targeted by antibodies in plasma samples from convalescent SARS patients through biopanning with a vast M13 phage display dodecapeptide library. These epitopes converged to very short peptide fragments, one on each of the structural proteins spike and nucleocapsid and the nonstructural proteins 3a, 9b, and nsp 3. Immunoassays found that most of the patients who had recovered from SARS developed complementary antibodies to the epitope-rich region on the spike S2 protein, indicating that this is an immunodominant site on the viral envelope comprising the spike, matrix, and small envelope glycoproteins. These S2-targeting antibodies were shown to effectively neutralize the coronavirus, indicating that they provided protective immunity to help the patients recover from the viral infection. These results suggest that the SARS coronavirus might have an antigenic profile distinct from those of other human or animal coronaviruses. Due to the tested safety and protective effects of the convalescent-phase serological antibodies, identification of their complementary antigens may enable the design of an epitope-based vaccine to prevent potential antibody-mediated immunuopathology.
PMCID: PMC1075701  PMID: 15731234

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