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Dawei Liu

Publications and source records attributed to Dawei Liu.

16 recordsLinked to original sources
PubMed2025

A Dual-Selection System for Enhanced Efficiency and Fidelity of Circular RNA Overexpression.

Circular RNAs (circRNAs) are essential regulators of cellular processes, but are challenging to study using traditional methods. Overexpression approaches, such as the use of linearized plasmids and viral vectors, often result in high rates of false-positive clones, where cells retain selection markers without expressing the target circRNA. This study addresses this limitation by developing a dual-selection circRNA system designed to enhance the accuracy and reliability of circRNA overexpression. Our system integrates a fluorescent reporter gene upstream of the circRNA expression cassette, under a shared promoter, and a downstream antibiotic resistance marker, allowing for both antibiotic selection and flow cytometric cell-sorting to identify and enrich cells with genuine circRNA expression. We successfully incorporated this system into an inducible lentiviral vector for controlled overexpression in various cell types. The dual-selection circRNA system offers a significant advance for circRNA research and studies of other RNA species where accurate and reliable overexpression is essential.

RNA, Circular↗
PubMed2025

ATAC-seq for Characterizing Host and Pathogen Genome Accessibility During Virus Infection.

Chromatin regulation provides a mechanism through which cells dynamically and rapidly regulate their gene expression profiles, playing a pivotal role in diverse biological processes and disease states. The Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) is a method that enables genome-wide detection of accessible chromatin regions, providing information on nucleosome positioning and the epigenetic regulation of the chromatin structure. ATAC-seq has been used in various biological contexts, and several reports have demonstrated its application to studying infections with viral or bacterial pathogens. The ability to characterize changes in viral or bacterial genome accessibility during infections provides insights into both pathogen replication and host defense mechanisms. Viral genomes undergo dynamic changes in their structural landscape to facilitate replication and evade host immune responses. Additionally, host cells encode DNA sensors, which are specialized proteins that bind to viral genomes to initiate innate immune responses and sometimes, to suppress viral gene expression. ATAC-seq enables the systematic detection of key structural changes on the viral genome mediated by either viral or host proteins, offering mechanistic insights into virus-host interactions. Here, we describe an ATAC-seq method optimized for studying changes in chromatin accessibility in both host and viral genomes. We have previously applied this method to demonstrate a systematic decrease in the genome accessibility of herpes simplex virus type I (HSV-1) enabled by a host antiviral factor, the interferon-gamma inducible protein 16 (IFI16) during infection of human fibroblasts. This protocol can be adapted to various biological contexts involving the introduction of foreign DNA, making it a valuable tool for a broad range of research endeavors.

Humans↗
PubMed2006

The Wnt co-receptor LRP5 is essential for skeletal mechanotransduction but not for the anabolic bone response to parathyroid hormone treatment.

The cell surface receptor, low-density lipoprotein receptor-related protein 5 (LRP5) is a key regulator of bone mass. Loss-of-function mutations in LRP5 cause the human skeletal disease osteoporosis-pseudoglioma syndrome, an autosomal recessive disorder characterized by severely reduced bone mass and strength. We investigated the role of LRP5 on bone strength using mice engineered with a loss-of-function mutation in the gene. We then tested whether the osteogenic response to mechanical loading was affected by the loss of Lrp5 signaling. Lrp5-null (Lrp5-/-) mice exhibited significantly lower bone mineral density and decreased strength. The osteogenic response to mechanical loading of the ulna was reduced by 88 to 99% in Lrp5-/- mice, yet osteoblast recruitment and/or activation at mechanically strained surfaces was normal. Subsequent experiments demonstrated an inability of Lrp5-/- osteoblasts to synthesize the bone matrix protein osteopontin after a mechanical stimulus. We then tested whether Lrp5-/- mice increased bone formation in response to intermittent parathyroid hormone (PTH), a known anabolic treatment. A 4-week course of intermittent PTH (40 microg/kg/day; 5 days/week) enhanced skeletal mass equally in Lrp5-/- and Lrp5+/+ mice, suggesting that the anabolic effects of PTH do not require Lrp5 signaling. We conclude that Lrp5 is critical for mechanotransduction in osteoblasts. Lrp5 is a mediator of mature osteoblast function following loading. Our data suggest an important component of the skeletal fragility phenotype in individuals affected with osteoporosis-pseudoglioma is inadequate processing of signals derived from mechanical stimulation and that PTH might be an effective treatment for improving bone mass in these patients.

Anabolic Agents↗
PubMed2006

Hydrogen and methane production from household solid waste in the two-stage fermentation process.

A two-stage process combined hydrogen and methane production from household solid waste was demonstrated working successfully. The yield of 43 mL H(2)/g volatile solid (VS) added was generated in the first hydrogen production stage and the methane production in the second stage was 500 mL CH(4)/g VS added. This figure was 21% higher than the methane yield from the one-stage process, which was run as control. Sparging of the hydrogen reactor with methane gas resulted in doubling of the hydrogen production. pH was observed as a key factor affecting fermentation pathway in hydrogen production stage. The optimum pH range for hydrogen production in this system was in the range from 5 to 5.5. The short hydraulic retention time (2 days) applied in the first stage was enough to separate acidogenesis from methanogenesis. No additional control for preventing methanogenesis in the first stage was necessary. Furthermore, this study also provided direct evidence in the dynamic fermentation process that, hydrogen production increase was reflected by acetate to butyrate ratio increase in liquid phase.

Acetates↗
PubMed2005

The P2X7 nucleotide receptor mediates skeletal mechanotransduction.

The P2X7 nucleotide receptor (P2X7R) is an ATP-gated ion channel expressed in many cell types including osteoblasts and osteocytes. Mice with a null mutation of P2X7R have osteopenia in load bearing bones, suggesting that the P2X7R may be involved in the skeletal response to mechanical loading. We found the skeletal sensitivity to mechanical loading was reduced by up to 73% in P2X7R null (knock-out (KO)) mice. Release of ATP in the primary calvarial osteoblasts occurred within 1 min of onset of fluid shear stress (FSS). After 30 min of FSS, P2X7R-mediated pore formation was observed in wild type (WT) cells but not in KO cells. FSS increased prostaglandin (PG) E2 release in WT cells but did not alter PGE2 release in KO cells. Studies using MC3T3-E1 osteoblasts and MLO-Y4 osteocytes confirmed that PGE2 release was suppressed by P2X7R blockade, whereas the P2X7R agonist BzATP enhanced PGE2 release. We conclude that ATP signaling through P2X7R is necessary for mechanically induced release of prostaglandins by bone cells and subsequent osteogenesis.

Adenosine Triphosphate↗
PubMed2005

Team leadership and patient outcomes in US psychiatric treatment settings.

Previous studies suggest that psychiatric patients mirror the behaviors of the staff members who treat them, but there is little empirical evidence about how staff dynamics affect patients over time. The goals of this study were to examine associations between: (1) team leader discipline and mutual respect among treatment team members; and (2) mutual respect among team members and improvements in patient quality of life. Two models were tested on data from psychiatric treatment teams within the US Veterans Administration. The first examined associations between the discipline of each team's emergent leader and the level of mutual respect among that team's members. The second model tested associations between mutual respect among staff and changes over time in patients' quality of life. The subjects for model 1 were psychiatric staff members (n=785) whose responses were aggregated for team-level analyses (n=78). Mutual respect was highest in social worker-led teams and lowest in physician-led teams. The subjects for model 2 were 1,638 seriously mentally ill patients in 44 of the units examined in the first model. When mutual respect among staff was greater, patients improved more over time in their satisfaction with the quality of their housing, relations with families, social life, and finances. Together, these analyses imply that mutual respect may improve patient outcomes and that leadership by some disciplines may facilitate such dynamics. In general, leaders may consider learning from other disciplines' strengths to improve their impact.

Hospitals, Psychiatric↗
PubMed2005

Cross-functional team processes and patient functional improvement.

OBJECTIVE: To test the hypothesis that higher levels of participation and functioning in cross-functional psychiatric treatment teams will be related to improved patient outcomes. DATA SOURCES/STUDY SETTING: Primary data were collected during the period 1992-1999. The study was conducted in 40 teams within units treating seriously mentally ill patients in 16 Veterans Affairs hospitals across the U.S. STUDY DESIGN: A longitudinal, multilevel analysis assessed the relationship between individual- and team-level variables and patients' ability to perform activities of daily living (ADL) over time. Team data were collected in 1992, 1994, and 1995. The number of times patient data were collected was dependent on the length of time the patient was treated and varied from 1 to 14 between 1992 and 1999. Key variables included: patients' ADL scores (the dependent variable); measures of team participation and team functioning; the number of days from baseline on which a patient's ADLs were assessed; and several control variables. DATA COLLECTION METHODS: Team data were obtained via self-administered questionnaires distributed to staff on the study teams. Additional team data were obtained via questionnaires completed by unit directors contemporaneously with the staff survey. Patient data were collected by trained clinicians at regular intervals using a standard assessment instrument. PRINCIPAL FINDINGS: Results indicated that patients treated in teams with higher levels of staff participation experienced greater improvement in ADL over time. No differences in ADL change were noted for patients treated in teams with higher levels of team functioning. CONCLUSIONS: Findings support our premise that team process has important implications for patient outcomes. The results suggest that the level of participation by the team as a whole may be a more important process attribute, in terms of patient improvements in ADLs, than the team's smooth functioning. These findings indicate the potential appropriateness of managerial interventions to encourage member investment in team processes.

Activities of Daily Living↗
PubMed2004

Fluid shear-induced ATP secretion mediates prostaglandin release in MC3T3-E1 osteoblasts.

UNLABELLED: ATP is rapidly released from osteoblasts in response to mechanical load. We examined the mechanisms involved in this release and established that shear-induced ATP release was mediated through vesicular fusion and was dependent on Ca2+ entry into the cell through L-type voltage-sensitive Ca2+ channels. Degradation of secreted ATP by apyrase prevented shear-induced PGE2 release. INTRODUCTION: Fluid shear induces a rapid rise in intracellular calcium ([Ca2+]i) in osteoblasts that mediates many of the cellular responses associated with mechanotransduction in bone. A potential mechanism for this increase in [Ca2+]i is the activation of purinergic (P2) receptors resulting from shear-induced extracellular release of ATP. This study was designed to determine the effects of fluid shear on ATP release and the possible mechanisms associated with this release. MATERIALS AND METHODS: MC3T3-E1 preosteoblasts were plated on type I collagen, allowed to proliferate to 90% confluency, and subjected to 12 dynes/cm2 laminar fluid flow using a parallel plate flow chamber. ATP release into the flow media was measured using a luciferin/luciferase assay. Inhibitors of channels, gap junctional intercellular communication (GJIC), and vesicular formation were added before shear and maintained in the flow medium for the duration of the experiment. RESULTS AND CONCLUSIONS: Fluid shear produced a transient increase in ATP release compared with static MC3T3-E1 cells (59.8 +/- 15.7 versus 6.2 +/- 1.8 nM, respectively), peaking within 1 minute of onset. Inhibition of calcium entry through the L-type voltage-sensitive Ca2+ channel (L-VSCC) with nifedipine or verapamil significantly attenuated shear-induced ATP release. Channel inhibition had no effect on basal ATP release in static cells. Ca(2+)-dependent ATP release in response to shear seemed to result from vesicular release and not through gap hemichannels. Vesicle disruption with N-ethylmaleimide, brefeldin A, or monensin prevented increases in flow-induced ATP release, whereas inhibition of gap hemichannels with either 18alpha-glycyrrhetinic acid or 18beta-glycyrrhetinic acid did not. Degradation of extracellular ATP with apyrase prevented shear-induced increases in prostaglandin E2 (PGE2) release. These data suggest a time line of mechanotransduction wherein fluid shear activates L-VSCCs to promote Ca2+ entry that, in turn, stimulates vesicular ATP release. Furthermore, these data suggest that P2 receptor activation by secreted ATP mediates flow-induced prostaglandin release.

Adenosine Triphosphate↗
PubMed2004

Psychosocial effects of the BOOT STRAP intervention in Navy recruits.

The purpose of this prospective study was to investigate the effects of the Boot Camp Survival Training for Navy Re cruits--A Prescription (BOOT STRAP) intervention on stress depression, situational events, interpersonal factors, and recruit training performance. Divisions of Navy recruits were randomly selected and 801 recruits participated for the 9 weeks of their training. Recruits "at risk" for depression were randomly assigned to the intervention or nonintervention groups, and the remaining recruits served as the comparison group. The at-risk recruits who received the BOOT STRAP intervention significantly increased their sense of belonging, experienced less loneliness, used more problem-solving coping skills, and decreased insecure attachment by the end of recruit training. Percentages of recruits in the study success fully completing basic training were 84% of the comparison group, 86% of the intervention group, and only 74% of the nonintervention group. Results suggest that the BOOT STRAP intervention improves recruit functioning, strengthens train ing performance, helps reduce attrition, and may have impor tant implications for stress and depression interventions.

Adaptation, Psychological↗
PubMed2003

Restriction of third-generation cephalosporin use decreases infection-related mortality.

OBJECTIVE: To determine the effect of restriction of third-generation cephalosporin use on antibiotic resistance and the outcome of patients with infection. DESIGN: A prospective, before-after comparative study. SETTING: A general intensive care unit with 14 beds at a university-affiliated teaching hospital. PATIENTS: All patients admitted to the intensive care unit within 2 yrs. INTERVENTIONS: A new antibiotic treatment strategy was implemented during phase II. All patients with confirmed or suspected Gram-negative bacterial infections were treated mainly with antibiotics other than third-generation cephalosporins. MEASUREMENTS AND MAIN RESULTS: Antibiotic resistance among common Gram-negative bacilli and infection-related hospital mortality during phase I were compared with phase II. A 26.6% reduction in third-generation cephalosporin use (from 168.2 +/- 48.0 to 123.5 +/- 39.3 g/month, p =.021), accompanied by a 277.7% increase in cefepime use (from 10.3 +/- 19.2 to 38.9 +/- 31.7 g/month, p =.014) occurred in phase II compared with phase I. This was accompanied by a significant decrease in reduced susceptibility of Gram-negative bacilli to third-generation cephalosporins (p <.05), mainly because of the improved susceptibility of Escherichia coli and Klebsiella species (p <.05). Infection-related hospital mortality was significantly lower in phase II (19.3% vs. 36.3%, p =.014). Multiple logistic regression analysis demonstrated lower respiratory tract infection, the status of immunocompromise, and continuous veno-venous hemofiltration as independent risk factors for infection-related hospital mortality (p <.05), whereas infection with E. coli or Klebsiella species (p =.039) and restriction of third-generation cephalosporin use (p =.025) were associated with a significantly lower mortality rate. CONCLUSIONS: Restriction of third-generation cephalosporin use may improve the antibiotic susceptibility and reduce infection-related hospital mortality in critically ill patients.

APACHE↗
PubMed2002

Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infection: risk factors and clinical outcome.

OBJECTIVES: To study the risk factor for nosocomial bacteremia caused by Escherichia coli or Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) and the influence on patient outcome. DESIGN: Retrospective, single-center study of consecutive bacteremic patients. SETTINGS: A university-affiliated teaching hospital. PATIENTS: A total of 85 patients with nosocomial bacteremia due to E. coli or K. pneumoniae were enrolled. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The demographic characteristics and clinical information including treatment were recorded upon review of patients' records. The primary end point was hospital mortality. Twenty-seven percent of isolates produced ESBLs. Previous treatment with 3rd-generation cephalosporins was the only independent risk factor for bacteremia due to ESBL-producing pathogens [odds ratio (OR) 4.146, P=0.008]. Antibiotic treatment was considered appropriate in 71 cases (83%), and failed in 23 patients (27%). Twenty-one patients (25%) died in the hospital. Antibiotic treatment failure was the only independent risk factor for hospital mortality (OR 15.376, P=0.001). Inappropriate antibiotic treatment might lead to significantly higher mortality rate (7/14 vs 14/71, P=0.016). Patients treated with imipenem were more likely to survive while those receiving cephalosporin treatment tended to have a poorer outcome (1/19 vs 14/40, P=0.023). CONCLUSIONS: More judicious use of cephalosporins, especially 3rd-generation cephalosporins, may decrease ESBL-producing E. coli or K. pneumoniae bacteremia, and also improve patient outcome.

APACHE↗
PubMed2002

Effect of hypertonic saline solution on the left ventricular functions of isolated hearts from burned rats.

OBJECTIVE: To study the effect of hypertonic saline solution on the left ventricular functions of isolated hearts from burned rats. METHODS: Thirty-six Wistar rats were used and divided into 4 groups: (1) normal hearts perfused with isotonic Krebs-Henseleit solution; (2) normal hearts perfused with Krebs-Henseleit solution which contained 215 mmol/L Na+; (3) hearts of rats suffered from 25% TBSA third degree burn and perfused with isotonic Krebs-Henseleit solution; (4) hearts of the burned rats perfused with Krebs-Henseleit solution which contained 215 mmol/L Na+. The systolic and diastolic functions of the left ventricle were observed. RESULTS: During perfusion, there were very short periods of decrease in heart systolic and diastolic functions at first, but they recovered very soon and even became stronger than normal both in the normal and burned rats. The systolic and diastolic functions of the hearts increased very significantly when the perfusion solution was changed to isotonic solution from the hypertonic solutions. The effect of the hypertonic saline solution on the ventricular systolic and diastolic improvements was stronger in the hearts of the burned rats than that in the normal hearts. CONCLUSIONS: Hypertonic saline solution can directly affect myocardium and significantly improve the ventricular systolic and diastolic functions, especially in the hearts of the burned rats.

Animals↗
PubMed1999

Effect of bactericidal/permeability-increasing protein on sepsis induced by intra-abdominal infection in rats.

OBJECTIVE: To investigate the effect and mechanism of bactericidal/permeability-increasing protein (BPI) on sepsis induced by intra-abdominal infection in rats. METHODS: Cecal ligation and puncture (CLP) was made on 20 rats with sepsis induced by intra-abdominal infection. BPI or equal volume of physiological saline (PS) was intra-abdominally given immediately and 12 h after CLP, respectively (2.5 mg/kg of BPI each time). Plasma endotoxin levels were determined with limulus amebocyte chromogenic assay. RESULTS: (1) The survival time in BPI group was significantly higher than that in PS group. (2) The values of the mean arterial pressure (MAP), the left ventricular systolic pressure (LVSP), the isovolumic ventricular pressure (IP), and the maximal change of left intraventricular pressure (+/-dp/dtmax) in BPI group, although decreasing, were markedly higher than those in PS group. (3) Plasma glutamic-pyruvic transaminase (GPT) and urea nitrogen levels in BPI group, though increasing, were obviously lower than those in PS group. (4) There was no significant change of plasma endotoxin levels in BPI group, while plasma endotoxin levels markedly increased in PS group. CONCLUSIONS: BPI has obvious protective effect on sepsis induced by intra-abdominal infection, which might be related to its neutralization of endotoxin.

Journal Article↗
PubMed1998

Protective effect of bactericidal/permeability-increasing protein in mice with E. coli sepsis.

OBJECTIVE: To investigate the effect of bactericidal/permeability-increasing protein(BPI) on the outcome of sepsis in mice and its possible mechanism. METHODS: Sepsis was induced by injection of 2x10(6) colony-formed unit E. coli J5 via the tail vein. BPI of 5 mg/kg or equal volume of normal saline(NS) were injected intravenously at the same time. Endotoxin and TNFalpha levels in serum were assayed using a chromogenic limulus amebocyte lysate test and ELISA respectively. RESULTS: Seventy-two hour survival rate of septic mice was significantly higher in the BPI group (15/18) than in the NS group(8/18, P<0.01). Serum endotoxin levels in the BPI group (1.3+/-0.3 and 0.7+/-0.4 &mgr;g/L) were significantly lower than those in the NS group (3.9+/-0.8 and 2.5+/-0.9 &mgr; g/L, P<0.01) 0.5 and 1 hour following injection of bacteria respectively. The peak levels of serum tumor necrosis factor-alpha(TNFalpha)in the BPI group (1.9+/-0.6 &mgr;g/L) were also markedly lower than those in the NS group (3.8+/-0.8 &mgr;g/L, P<0.01) 1.5 hours following bacterial injection. But there was no significant difference in blood bacterial count between the BPI and NS groups 0.5, 1.5 and 3.0 hours after injection of bacteria. CONCLUSIONS: BPI has a marked protective effect on E. coli sepsis, which might be related to its action against bacterial endotoxin and its inhibition of TNFalpha production in sepsis.

Journal Article↗