Biomedical subjects

Jie Xiao

Publications and source records attributed to Jie Xiao.

At least 19 recordsLinked to original sources

PubMed2026

MDV-like endogenous viral elements act as immune rheostats in Aedes cells by modulating defensin A-mediated responses to arboviruses.

Mosquito cell lines are essential tools for arbovirus research. Endogenous viral elements (EVEs) are prevalent in mosquito genomes, yet their functional effects on host immune responses remain unclear, potentially complicating experimental interpretations. In this study, we systematically characterized endogenous mosquito densovirus-like elements (EMLs) within the Aedes aegypti Aag2 cell line and found that these endogenous EMLs are transcriptionally active but translationally defective. The silencing of EML transcripts significantly diminished the replication of Zika virus (ZIKV), Japanese encephalitis virus (JEV), and chikungunya virus (CHIKV), while transiently increasing dengue virus 2 (DENV-2), thereby indicating a virus-dependent regulatory mechanism. Mechanistically, RNA sequencing after EML interference, alongside plasmid-based mimic expression, demonstrated that EML transcripts downregulate defensin A, an antimicrobial peptide produced by mosquitoes. Functional assays using synthetic defensin A showed that this peptide differentially regulates arboviral infection. Binding assays and structural modeling further supported its interaction with viral envelope proteins, while stage-restricted infection assays revealed distinct stages of action: defensin A enhanced adsorption of ZIKV, JEV, and CHIKV, but did not promote DENV-2 adsorption or entry, and instead reduced DENV-2 RNA accumulation at the post-entry replication stage. Our findings highlight a previously unrecognized role of densovirus-derived EVEs in mosquito innate immunity, extending their functional scope from the well-established PIWI-interacting RNA-mediated antiviral defense to the regulation of antimicrobial peptide-associated immune pathways. These findings emphasize the necessity of accounting for EVE activity when analyzing data derived from mosquito cell lines, and suggest that related EVE-mediated immune regulation may contribute to arbovirus dynamics in mosquitoes.IMPORTANCEMosquito-borne viruses such as dengue, Zika, Japanese encephalitis, and chikungunya continue to threaten human health worldwide. Laboratory studies often use Aedes aegypti cell lines to investigate how these viruses interact with their mosquito hosts. Here, we show that the genomes of these cells contain endogenous viral elements derived from mosquito densoviruses. Far from being inert fossils, these sequences are transcriptionally active and regulate mosquito immunity by suppressing the antimicrobial peptide defensin A. This immune modulation influences the replication of different arboviruses in opposite ways, enhancing some while restricting others. Our findings reveal that integrated viral elements can shape the outcome of arbovirus infection, with important implications for interpreting mosquito cell culture experiments and for evaluating endogenous viral element-mediated immune regulation in mosquito-virus interactions.

Aag2 cell↗

PubMed2024

Effects of different temperatures on chondrocyte growth: a transcriptomic analysis.

BACKGROUND: Our previous study demonstrated that temperature-related microwave ablation (MWA) can safely modulate growth plates of piglets' vertebrae. Therefore, this study is designed to investigate the effects of different temperatures on chondrocyte viability and the underlying molecular mechanisms in vitro. METHODS: Following a 10-minute treatment at different temperatures (37 °C, 40 °C, 42 °C, 44 °C, 46 °C, 48 °C, and 50 °C), CCK-8 assay was used to examine the viability of ATDC5 cells at 12 h. Differentially expressed genes (DEGs) and the hub genes in ATDC5 cells treated at 37 °C, 40 °C and 44 °C were identified using RNA-seq. The expression of hub genes in ATDC5 cells was validated using RT-qPCR. RESULTS: Compared with 37 °C, exposure to 40 °C significantly increased the viability of ATDC5 cells, while 42 °C had no significant effect. Additionally, exposure to 44 °C, 46 °C, 48 °C, and 50 °C exhibited the opposite pattern, with ATDC5 cells being particularly less than 50% active after treatment at 46 °C, 48 °C, and 50 °C. Differential expression analysis identified 179, 374 and 221 DEGs in the comparisons of 40 °C vs. 37 °C, 44 °C vs. 37 °C, and 44 °C vs. 40 °C, respectively. These DEGs predominantly regulated proliferation, differentiation, necrosis, inflammatory and immune responses, and ECM synthesis/degradation. Furthermore, they were associated with the Ras, PI3K/AKT, mTOR, cAMP, and MAPK pathways. Agt, Hspa1a, Hspb1, and Nlrc4 were identified as hub genes in DEGs, and RT-qPCR confirmed that the mRNA expression patterns of these hub genes in ATDC5 cells were largely consistent with the RNA-seq results. CONCLUSION: The regulation of chondrocyte viability by temperature is associated with Ras, PI3K/AKT, mTOR, cAMP, and MAPK pathways. Additionally, Agt, Hspa1a, Hspb1, and Nlrc4 may be the key regulatory genes in this process.

Chondrocytes↗

PubMed2006

The electronic structures of Co and Ni tetraazaannulenes.

We compare the electronic structure of two metal-centered tetramethyldibenzo-tetraazaannulene (TMTAA) macrocyclic complex molecules: 5,7,12,14- tetramethyl-2,3:9,10-dibenzo[b,i]-1,4,8,11-tetraazacyclotetradecine nickel (II) and 5,7,12,14-tetramethyl-2,3:9,10-dibenzo[b,i]-1,4,8,11-tetraazacyclotetradecine cobalt (II). The experimental gap between the highest occupied molecular orbital to the lowest unoccupied molecular orbital for both molecules, obtained from combined ultraviolet photoemission and inverse photoemission studies, is close to the value of 6.6 eV expected from simple model calculations, but with the Fermi level placed closer to the lowest unoccupied molecular orbital. While both the Co(II) (s = 1/2) and Ni(II) (s = 0) TMTAA molecular electronic structures are very similar, the Ni(II) adopts a high-symmetry molecular configuration upon adsorption, with a strong preferential orientation.

Journal Article↗

PubMed2006

Origins of sequence selectivity in homologous genetic recombination: insights from rapid kinetic probing of RecA-mediated DNA strand exchange.

Despite intense effort over the past 30 years, the molecular determinants of sequence selectivity in RecA-mediated homologous recombination have remained elusive. Here, we describe when and how sequence homology is recognized between DNA strands during recombination in the context of a kinetic model for RecA-mediated DNA strand exchange. We characterized the transient intermediates of the reaction using pre-steady-state kinetic analysis of strand exchange using oligonucleotide substrates containing a single fluorescent G analog. We observed that the reaction system was sensitive to heterology between the DNA substrates; however, such a "heterology effect" was not manifest when functional groups were added to or removed from the edges of the base-pairs facing the minor groove of the substrate duplex. Hence, RecA-mediated recombination must occur without the involvement of a triple helix, even as a transient intermediate in the process. The fastest detectable reaction phase was accelerated when the structure or stability of the substrate duplex was perturbed by internal mismatches or the replacement of G.C by I.C base-pairs. These findings indicate that the sequence specificity in recombination is achieved by Watson-Crick pairing in the context of base-pair dynamics inherent to the extended DNA structure bound by RecA during strand exchange.

Base Pair Mismatch↗

PubMed2006

Construction and evaluation of a kinetic scheme for RecA-mediated DNA strand exchange.

The Escherichia coli RecA protein is the prototype of a class of proteins playing a central role in genomic repair and recombination in all organisms. The unresolved mechanistic strategy by which RecA aligns a single strand of DNA with a duplex DNA and mediates a DNA strand switch is central to understanding its recombinational activities. Toward a molecular-level understanding of RecA-mediated DNA strand exchange, we explored its mechanism using oligonucleotide substrates and the intrinsic fluorescence of 6-methylisoxanthopterin (6MI). Steady- and presteady-state spectrofluorometric data demonstrate that the reaction proceeds via a sequential four-step mechanism comprising a rapid, bimolecular association step followed by three slower unimolecular steps. Previous authors have proposed multistep mechanisms involving two or three steps. Careful analysis of the differences among the experimental systems revealed a previously undiscovered intermediate (N1) whose formation may be crucial in the kinetic discrimination of homologous and heterologous sequences. This observation has important implications for probing the fastest events in DNA strand exchange using 6MI to further elucidate the molecular mechanisms of recombination and recombinational repair.

Base Sequence↗

PubMed2006

On-line optimization of glutamate production based on balanced metabolic control by RQ.

In glutamate fermentations by Corynebacterium glutamicum, higher glutamate concentration could be achieved by constantly controlling dissolved oxygen concentration (DO) at a lower level; however, by-product lactate also severely accumulated. The results of analyzing activities changes of the two key enzymes, glutamate and lactate dehydrogenases involved with the fermentation, and the entire metabolic network flux analysis showed that the lactate overproduction was because the metabolic flux in TCA cycle was too low to balance the glucose glycolysis rate. As a result, the respiratory quotient (RQ) adaptive control based "balanced metabolic control" (BMC) strategy was proposed and used to regulate the TCA metabolic flux rate at an appropriate level to achieve the metabolic balance among glycolysis, glutamate synthesis, and TCA metabolic flux. Compared with the best results of various DO constant controls, the BMC strategy increased the maximal glutamate concentration by about 15% and almost completely repressed the lactate accumulation with competitively high glutamate productivity.

Citric Acid Cycle↗

PubMed2006

Probing gene expression in live cells, one protein molecule at a time.

We directly observed real-time production of single protein molecules in individual Escherichia coli cells. A fusion protein of a fast-maturing yellow fluorescent protein (YFP) and a membrane-targeting peptide was expressed under a repressed condition. The membrane-localized YFP can be detected with single-molecule sensitivity. We found that the protein molecules are produced in bursts, with each burst originating from a stochastically transcribed single messenger RNA molecule, and that protein copy numbers in the bursts follow a geometric distribution. The quantitative study of low-level gene expression demonstrates the potential of single-molecule experiments in elucidating the workings of fundamental biological processes in living cells.

Bacterial Proteins↗

PubMed2006

Direct evaluation of a kinetic model for RecA-mediated DNA-strand exchange: the importance of nucleic acid dynamics and entropy during homologous genetic recombination.

The Escherichia coli RecA protein is the prototype of a class of proteins that play central roles in genomic repair and recombination in all organisms. The unresolved mechanistic strategy by which RecA aligns a single strand of DNA with a duplex DNA and mediates a DNA strand switch is central to understanding homologous recombination. We explored the mechanism of RecA-mediated DNA-strand exchange using oligonucleotide substrates with the intrinsic fluorophore 6-methylisoxanthopterin. Pre-steady-state spectrofluorometric analysis elucidated the earliest transient intermediates formed during recombination and delineated the mechanistic strategy by which RecA facilitates this process. The structural features of the first detectable intermediate and the energetic characteristics of its formation were consistent with interactions between a few bases of the single-stranded DNA and the minor groove of a locally melted or stretched duplex DNA. Further analysis revealed RecA to be an unusual enzyme in that entropic rather than enthalpic contributions dominate its catalytic function, and no unambiguously active role for the protein was detected in the earliest molecular events of recombination. The data best support the conclusion that the mechanistic strategy of RecA likely relies on intrinsic DNA dynamics.

DNA↗

PubMed2006

[Investigation and analysis of the bacteria community in silkworm intestine].

Majority of the environmental microorganisms are still unculturable. To shed a light on the bacteria community in the silkworm intestine more completely, culture-dependent and culture-independent methods were used to perform the investigation. As the latter, 16s rRNA gene was amplified and a library was constructed by using the meta-genomic DNA extracted from the bacteria in the silkworm intestine as template. Restriction fragment length polymorphism (RFLP) method was used to screen recombinants originated from different bacteria, and the nucleotide sequences were determined. A BLAST searching in the GenBank and an analysis on phylogenesis were performed. The taxonomy of these bacteria and their physiological function to silkworm were speculated. Results showed that the bacteria in silkworm intestine are mainly belong to the genera Arthrobacter, Lactobacillus, Pseudomonas, Escherichia, Micrococcus, Bacillus, and Staphylococcus. They may play important roles to the host silkworm in the utilization of their food mulberry and disease prevention. Both the culture-dependent and culture-independent methods have their advantages and disadvantages, and they are complemented with each other.

Animals↗

PubMed2005

Crystalline ice grown on the surface of the ferroelectric polymer poly(vinylidene fluoride) (70%) and trifluoroethylene (30%).

Water ice is observed to order at the copolymer ferroelectric poly(vinylidene difluoride-trifluoroethylene) surface. The successful growth of crystalline thin films of water on these polymer surfaces implicates water to polymer dipole interactions. These ice thin films are sufficiently ordered for experimental identification of the wave vector dependence in the electronic band structure of hexagonal ice. The significant band dispersion, of about 1 eV, suggests strong overlap of molecular orbitals between adjacent water molecules in the ice film. The presence of dipole interactions with adsorbate water is consistent with the possibility of water acting as a spectator to surface ferroelectric transitions in this system.

Journal Article↗

PubMed2005

Using quantitative CT to predict postoperative pulmonary function in patients with lung cancer.

BACKGROUND: At present, the therapy for patients with lung cancer that achieves a high rate of cure is surgical resection at an early stage of the disease. The aim of this study is to evaluate quantitative computed tomography (QCT) for predicting postoperative pulmonary function in patients with lung cancer. METHODS: The data of thirty-one patients with lung cancer who underwent both pulmonary functional tests and QCT scan before operations were collected. A CT program was used to quantify the volume of whole lung parenchyma with attenuation of -910 HU to -600 HU, which was defined as total functional lung volume (TFLV). Similarly, the volume of lung (lobes or segments) with attenuation of -910 HU to -600 HU was defined as regional functional lung volume (RFLV). Forced vital capacity (FVC), forced expiratory volume in first second (FEV1), FVC% and FEV1% (ratio to reference values of the matched population) were obtained from preoperational pulmonary functional tests. According to the formula: predicted FVC (pre-FVC) = preoperative FVC x [1-(RFLV/TFLV)]; predicted FEV1 (pre-FEV1) = preoperative FEV1 x [1-(RFLV/TFLV)], we obtained values of predicted FVC, predicted FEV1, predicted FVC% (pre-FVC/reference values of the matched population), and predicted FEV1% (pre-FEV1/reference values of the matched population). The paired t test and Pearson correlation test were used to assess significance of differences and correlations between CT predicted values and postoperative measured results of FVC, FEV1, FVC% and FEV1%. RESULTS: QCT predicted values correlated well with postoperative FVC, FEV1, FVC% and FEV1% (r = 0.873, 0.809, 0.849 and 0.801 respectively, all P < 0.01). CONCLUSIONS: QCT is an effective and accurate way to predict postoperative pulmonary function in patients undergoing pulmonary resection, regardless of the patients' preoperative pulmonary functional status.

Female↗

PubMed2004

Angiotensin-converting enzyme inhibitor usage in patients with incidental atherosclerotic renal artery stenosis.

The efficacy of angiotensin converting enzyme (ACE) inhibitors in treatment of renovascular disease has been controversial. It has been reported that patients with incidental atherosclerotic renal artery stenosis (ARAS) are sometimes treated with ACE inhibitors before being considered for renal revascularization. This study was designed to describe the frequency and the characteristics of patients with incidental ARAS, and to examine the frequency of ACE inhibitor usage in such patients. We studied a cohort of consecutive patients undergoing abdominal aortography at the time of cardiac catheterization. Patients were stratified and compared based on the presence and severity of ARAS. ARAS (> or =50%) was present in 146 (17.0%) of 859 evaluable patients. Factors independently related to the presence of ARAS were age (odds ratio (OR)=1.07, p < 0.001), severity of coronary artery disease (OR=2.13, p < 0.001) and peripheral vascular disease (OR=1.79, p = 0.021). Among all patients with ARAS, the percentage of ACE inhibitor usage was 74.7% (109/146). Among patients with severe ARAS, moderate ARAS, mild ARAS, insignificant ARAS and normal renal arteries, the percentage of ACE inhibitor usage was 85.7% (95% confidence interval (CI): 69-100%), 82.9% (95% CI: 71-95%), 68.5% (95% CI: 59-78%), 68.6% (95% CI: 55-82%) and 53.9% (95% CI: 50-58%), respectively (contingency coefficient=0.17, p < 0.001). In patients with severe ARAS, ACE inhibitor use, calcium channel blocker use and diuretic use were shown to correlate significantly with serum creatinine levels after controlling for potential confounding factors. In this study, ACE inhibitors were used commonly in patients with incidental ARAS; the frequency of ACE inhibitor use correlated with the severity of ARAS.

Aged↗

PubMed2004

Ant colony system algorithm for the optimization of beer fermentation control.

Beer fermentation is a dynamic process that must be guided along a temperature profile to obtain the desired results. Ant colony system algorithm was applied to optimize the kinetic model of this process. During a fixed period of fermentation time, a series of different temperature profiles of the mixture were constructed. An optimal one was chosen at last. Optimal temperature profile maximized the final ethanol production and minimized the byproducts concentration and spoilage risk. The satisfactory results obtained did not require much computation effort.

Algorithms↗

PubMed2004

[Convolution spectrometric determination of the effect of hydroxyl radical scavenger on UV radiation-induced DNA aberrance].

Convolution spectrometry was applied to determining the DNA aberrance induced by UV-A, UV-B and UV-C radiation, and the extent of minute aberrance was quantitatively expressed by the differential value of convolution spectra. The differential values of DNA solutions irradiated by UV-A, UV-B and UV-C increase in turn, indicating an increscent DNA aberrance. The addition of dimethylsulfoxide or mannitol to DNA solution decreases the differential value in respective way under UV-A, UV-B and UV-C radiation, representing different inhibitory effects. Dimethylsulfoxide decreases the UV-A-induced DNA aberrance by 60% (approximate value), UV-C-induced aberrance by 35% (approximate value), and UV-B-induced aberrance by 20% (approximate value), while mannitol shows similar inhibitory effects (40%, approximate value) for UV-A, UV-B and UV-C-induced DNA aberrance. Although the extent of DNA aberrance varies, the distribution of differential points of convolution spectra reveals that the types of UV radiation-induced DNA aberrance are similar, and the inhibitory mechanism of two hydroxyl radical scavengers is possibly the same.

DNA↗

PubMed2003

[The clinical staging and tissue bacterial quantification in the diagnosis of burn wound sepsis].

OBJECTIVE: To investigate and re-evaluate the relationship between burn wound sepsis and tissue bacterial quantity. METHODS: Thirty-two patients admitted during past 5 years were enrolled in the study. Bacterial isolation and quantity in burn wound tissue were carried out. Meanwhile clinical signs were evaluated for the staging of burn wound sepsis. RESULTS: 1) Bacterial invasion could be identified in 123 pieces of tissue samples from 32 patients. Samples with tissue bacterial quantity > or = 10(5)/g were found in 82 subeschar tissue samples, and 41 samples with bacteria <10(5)/g. Subeschar tissue samples with bacterial quantity > or = 10(5)/g could be determined in 68 samples from 18 patients, and < 10(5)/g in 20 samples from 5 cases. In addition, samples of subeschar tissue with bacterial quantity > or = 10(5)/g could only be found in some of the samples form 9 cases. 2) Burn wound sepsis could be classified into I-IV stages according to tissue bacterial quantification and clinical signs. CONCLUSION: Burn wound sepsis could be established by identification of bacterial invasion into living tissue with clinical symptoms of toxemia.

Adolescent↗

PubMed2003

Myocardial protective effects of electroacupuncture and hypothermia on porcine heart after ischemia/reperfusion.

The study was carried out in order to observe the protective effects of electroacupuncture (EA) and hypothermia on myocardial ischemic and reperfusion injury in pigs. Blood superoxide dismutase (SOD), malondialdehyde (MDA), creatine phosphokinase (CPK) and its isoenzyme (CK-MB), coronary artery flow (CAF) and myocardial heat-shock protein (HSP) mRNA expression were detected. It was observed that the MDA content increased and SOD activities decreased more significantly in control group compared with EA and EA+ hypothermia groups. CPK and CK-MB were found significantly increased in all three groups, but more remarkable in control group than in EA and EA+ hypothermia groups. HSP70 mRNA expression was found to be more in EA and EA+ hypothermia groups than that in control group 60 min after reperfusion. The results indicated that EA enhance the myocardial protection of hypothermia on ischemia/reperfusion injury. The mechanism may be related to the improvement of antioxidation and increased expression of HSP70 gene.

Animals↗

PubMed2003

Forecasting loss of ecosystem service value using a BP network: a case study of the impact of the South-to-north Water Transfer Project on the ecological environmental in Xiangfan, Hubei Province, China.

OBJECTIVE: To recognize and assess the impact of the South-to-north Water Transfer Project (SNWTP) on the ecological environment of Xiangfan, Hubei Province, situated in the water-out area, and develop sound scientific countermeasures. METHODS: A three-layer BP network was built to simulate topology and process of the eco-economy system of Xiangfan. Historical data of ecological environmental factors and socio-economic factors as inputs, and corresponding historical data of ecosystem service value (ESV) and GDP as target outputs, were presented to train and test the network. When predicted input data after 2001 were presented to trained network as generalization sets, ESVs and GDPs of 2002, 2003, 2004... till 2050 were simulated as output in succession. RESULTS: Up to 2050, the area would have suffered an accumulative total ESV loss of RMB104.9 billion, which accounted for 37.36% of the present ESV. The coinstantaneous GDP would change asynchronously with ESV, it would go through an up-to-down process and finally lose RMB89.3 billion, which accounted for 18.71% of 2001. CONCLUSIONS: The simulation indicates that ESV loss means damage to the capability of socio-economic sustainable development, and suggests that artificial neural networks (ANNs) provide a feasible and effective method and have an important potential in ESV modeling.

China↗

PubMed2002

Elucidating a key intermediate in homologous DNA strand exchange: structural characterization of the RecA-triple-stranded DNA complex using fluorescence resonance energy transfer.

The RecA protein of Escherichia coli plays essential roles in homologous recombination and restarting stalled DNA replication forks. In vitro, the protein mediates DNA strand exchange between single-stranded (ssDNA) and homologous double-stranded DNA (dsDNA) molecules that serves as a model system for the in vivo processes. To date, no high-resolution structure of the key intermediate, comprised of three DNA strands simultaneously bound to a RecA filament (RecA-tsDNA complex), has been reported. We present a systematic characterization of the helical geometries of the three DNA strands of the RecA-tsDNA complex using fluorescence resonance energy transfer (FRET) under physiologically relevant solution conditions. FRET donor and acceptor dyes were used to label different DNA strands, and the interfluorophore distances were inferred from energy transfer efficiencies measured as a function of the base-pair separation between the two dyes. The energy transfer efficiencies were first measured on a control RecA-dsDNA complex, and the calculated helical parameters (h approximately 5 A, Omega(h) approximately 20 degrees ) were consistent with structural conclusions derived from electron microscopy (EM) and other classic biochemical methods. Measurements of the helical parameters for the RecA-tsDNA complex revealed that all three DNA strands adopt extended and unwound conformations similar to those of RecA-bound dsDNA. The structural data are consistent with the hypothesis that this complex is a late, post-strand-exchange intermediate with the outgoing strand shifted by about three base-pairs with respect to its registry with the incoming and complementary strands. Furthermore, the bases of the incoming and complementary strands are displaced away from the helix axis toward the minor groove of the heteroduplex, and the bases of the outgoing strand lie in the major groove of the heteroduplex. We present a model for the strand exchange intermediate in which homologous contacts preceding strand exchange arise in the minor groove of the substrate dsDNA.

Adenosine Triphosphate↗