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Biomedical subjects

Hongwei Li

Publications and source records attributed to Hongwei Li.

52 records · Page 3Linked to original sources
PubMed2003

Isolation of Escherichia coli O157:H7 from dung beetles Catharsius molossus.

In an epidemiological survey, Escherichia coli O157:H7 was isolated from the intestine 4 of 113 dung beetle Catharsius molossus captured below ground at Tongshan County, Jiangsu Province of China. In parallel, 10 strains of E. coli O157:H7 were isolated from fecal samples of 383 diarrhea patients from the same region. Most importantly, using pulsed field gel electrophoresis (PFGE) of chromosomal DNA restriction fragments and PCR method, we found that the PFGE pattern and virulence genes of beetle isolates were identical to those of the human isolates, such as Shiga-toxins (stx) and enterohemorrhagic Escherichia coli hemolysin A (EHEC-hlyA). Therefore, dung beetle might acquire pathogenic E. coli O157:H7 through contact with feces of domestic animals.

Animals↗
PubMed2003

Experimental study on the function of cardiomyocytes.

This paper aimed at investigating the properties of cultured cardiomyocytes using microcirculatory and molecular technology to culture cardiomyocytes from different parts of the neonate Wistar rat's heart and record their spontaneous pulsation under time-lapse video microscopy, then analyze their activity and inspect their survival rate and apoptotic rate under natural and nitric oxide conditions. The pulsation frequency in cardiomtocytes of different parts in heart are: 78.5+/-11.0 beats/min in the atrium, 88.4+/-6.3 beats/min in the left ventricle, 90.3+/-7.9 beats/min in the right ventricle and 115.3 +/-11.4 beats/min in the cardiac apex, respectively, with an average frequency of 81.3 beats/min. Different concentrations of nitric oxide showed no effect on the frequency of cardiomyocyte pulsation. The survival rates of the above cardiomyocytes are 96.0%, 95.0%, 95.0%, and 95.3% respectively and 95.0% for the whole heart. The apoptotic rates are 1.3%, 1.1%, 4.8%, and 1.8% respectively and 5.1% for the whole heart. Different concentrations of nitric oxide had no effect on these results. Our study showed that cultured myocardial cells from different parts of the heart displayed various pulsation frequencies, and the frequency of the cardiac apex is the highest while the atrium is lowest. We also found that there is no statistically significant difference in the survival rates and apoptotic rates of different parts of the heart, and that nitric oxide has no effect on the beating frequency, survival rates or apoptotic rates of the cardiomyocytes in vitro.

Animals↗
PubMed2003

The mitogenic and anti-apoptotic activity of tumor conditioned medium on endothelium.

This study was designed to observe the effect of tumor conditioned medium (TCM) on the proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs). HUVECs were exposed to TCM from breast carcinoma cell line MDA-MB-231, then we measured their proliferation, apoptosis and cell cycle distribution by MTT and flow cytometery (FCM). Following the stimulation of TCM, HUVECs showed higher pro-mitogenic and anti-apoptotic ability than did the negative control group (ECGF-free medium with 20% FBS), but a similar ability to the positive control group (medium with ECGF and 20% FBS). From these results, we can conclude that breast carcinoma cell line MDA-MB-231 could secret soluble pro-angiogenic factors that induce HUVEC angiogenic switching, including cell cycle progression, proliferation and growth. The role and character of these factors remain to be further studied.

Angiogenesis Inducing Agents↗
PubMed2003

A proteomic study on cell cycle progression of endothelium exposed to tumor conditioned medium and the possible role of cyclin D1/E.

This study was designed to comprehensively analyze the differential expression of proteins from human umbilical vein endothelial cells (HUVECs) exposed to tumor conditioned medium (TCM) and to identify the key regulator in the cell cycle progression. The HUVECs were exposed to TCM from breast carcinoma cell line MDA-MB-231, then their cell cycle distribution was measured by flow cytometer (FCM). The role of protein in cell cycle progression was detected via two-dimensional polyacrylamide gel electrophoresis (2-DE) and western blotting. Following the stimulation of TCM, HUVECs showed a more cells in the S phase than did the negative control group (ECGF-free medium with 20% FBS), but the HUVECs' level was similar to the positive control group (medium with 25 micrograms/ml ECGF and 20% FBS). Increased expression of cyclin D1/E and some changes in other related proteins occurred after incubation with TCM. From our results, we can conclude that breast carcinoma cell line MDA-MB-231 may secrete soluble pro-angiogenic factors that induce the HUVEC angiogenic switch, during which the expression of cell cycle regulator cyclin D1/E increases and related proteins play an important role in this process.

Angiogenesis Inducing Agents↗
PubMed2002

Peroxynitrite inhibits Ca2+-activated K+ channel activity in smooth muscle of human coronary arterioles.

We examined the hypothesis that ONOO-, a product of the interaction between superoxide (O2*-) and nitric oxide (NO), inhibits calcium-activated K+ (KCa) channel activity in vascular smooth muscle cells (VSMCs) of human coronary arterioles (HCAs), thereby reducing hyperpolarization-mediated vasodilation. HCAs were dissected from right atrial appendages. The interaction of ONOO- with microvessels was determined by immunohistochemistry using a nitrotyrosine antibody. Strong staining was observed in arteries exposed to authentic ONOO- or to sodium nitroprusside (SNP)+xanthine (XA)+xanthine oxidase (XO). Dilation to 10(-8) mol/L bradykinin (BK) was abolished in vessels exposed to ONOO- (-2.5+/-8%; P<0.05) but not DC-ONOO- (65+/-8%). Reduced dilation to BK was also observed after application of XO and SNP. Dilation to NS1619 (KCa channel opener) was reduced in endothelial denuded arterioles treated with ONOO-. In isolated VSMCs, whole-cell peak K+ current density was reduced by ONOO- (control 65+/-15 pA/pF; ONOO- 42+/-9 pA/pF; P<0.05). Iberiotoxin had no further effect on whole-cell K+ current. In inside-out patches, ONOO- but not DC-ONOO- decreased open state probability (NP(o)) of KCa channel by 50+/-12%. O2*- generated by XA+XO had no effect on BK-induced dilation and NP(o) of KCa channels. These results suggest that ONOO-, but not O2*-, inhibits KCa channel activity in VSMCs possibly by a direct effect. This mechanism may contribute to impaired EDHF-mediated dilation in conditions such as ischemia/reperfusion where increased activity of NO synthase occurs in the presence of excess of O2*-.

Animals↗
PubMed2002

Lipopolysaccharide-induced methylation of HuR, an mRNA-stabilizing protein, by CARM1. Coactivator-associated arginine methyltransferase.

The RNA-binding protein HuR stabilizes labile mRNAs carrying AU-rich instability elements. This mRNA stabilization can be induced by hypoxia, lipopolysaccharide, and UV light. The mechanism by which these stimuli activate HuR is unclear and might be related to post-translational modification of this protein. Here we show that HuR can be methylated on arginine. However, HuR is not a substrate for PRMT1, the most prominent protein-arginine methyltransferase in mammalian cells, which methylates a number of heterogeneous nuclear ribonucleoproteins. Instead, HuR is specifically methylated by coactivator-associated arginine methyltransferase 1 (CARM1), a protein-arginine methyltransferase previously shown to serve as a transcriptional coactivator. By analyzing methylation of specific HuR arginine-to-lysine mutants and by sequencing radioactively methylated HuR peptides, Arg(217) was identified as the major HuR methylation site. Arg(217) is located in the hinge region between the second and third of the three HuR RNA recognition motif domains. Antibodies against a methylated HuR peptide were used to demonstrate in vivo methylation of HuR. HuR methylation increased in cells that overexpressed CARM1. Importantly, lipopolysaccharide stimulation of macrophages, which leads to HuR-mediated stabilization of tumor necrosis factor alpha mRNA in these cells, caused increased methylation of endogenous HuR. Thus, CARM1, which plays a role in transcriptional activation through histone H3 methylation, may also play a role in post-transcriptional gene regulation by methylating HuR.

Animals↗
PubMed2002

Induction and suppression of RNA silencing by an animal virus.

RNA silencing is a sequence-specific RNA degradation mechanism that is operational in plants and animals. Here, we show that flock house virus (FHV) is both an initiator and a target of RNA silencing in Drosophila host cells and that FHV infection requires suppression of RNA silencing by an FHV-encoded protein, B2. These findings establish RNA silencing as an adaptive antiviral defense in animal cells. B2 also inhibits RNA silencing in transgenic plants, providing evidence for a conserved RNA silencing pathway in the plant and animal kingdoms.

Agrobacterium tumefaciens↗
PubMed2002

Synergistic coactivator function by coactivator-associated arginine methyltransferase (CARM) 1 and beta-catenin with two different classes of DNA-binding transcriptional activators.

The androgen receptor (AR) binds to and activates transcription of specific genes in response to its cognate steroid hormone, dihydrotestosterone. Transcriptional activation by the DNA-bound AR is accomplished with the help of a variety of coactivator proteins. For example, the p160 coactivators bind directly to AR and recruit additional coactivators such as the histone acetyltransferase p300 and the histone methyltransferase CARM1. The current study tested whether CARM1 can cooperate with other types of coactivator proteins. Recently it was shown that beta-catenin can also bind directly to and serve as a coactivator for AR. Here it is shown that CARM1 binds to beta-catenin and can function in synergy with beta-catenin and p300 as coactivators for AR. The methyltransferase activity of CARM1 is important for its synergistic coactivator function with beta-catenin. The synergistic coactivator function of beta-catenin and CARM1 is not restricted to steroid receptors because these two coactivators can also act synergistically with another type of DNA binding transcriptional activator, LEF-1/TCF-4.

Acetyltransferases↗
PubMed2002

Ectopic osteogenesis using adenoviral bone morphogenetic protein (BMP)-4 and BMP-6 gene transfer.

Bone morphogenetic proteins (BMPs) delivered on scaffolds can induce ectopic bone formation after subcutaneous injection. Adenoviral vectors (Ad) carrying BMP2, BMP7, and BMP9 cDNAs have been shown to produce bone through endochondral ossification. The present study was performed to elucidate the histological events leading to ectopic ossification for two novel first-generation adenoviral constructs encoding BMPs, AdBMP4 and AdBMP6. In vitro, the viral constructs produced and secreted the mature BMP4 and BMP6 proteins. In vivo, the calf muscles of athymic nude rats were injected with AdBMP4, AdBMP6, AdBMP2, or AdlacZ. Rats were sacrificed 3, 6, 9, 16, 21, 60, and 90 days postinjection. Whereas AdBMP4 produced ectopic bone through mechanisms similar to endochondral ossification, AdBMP6 seemed to induce bone by way of mechanisms similar to both intramembranous and endochondral ossification pathways. At the relatively low vector dose used in this study, AdBMP2 caused an initial recruitment of primitive mesenchymal cells, without further development to bone. From computed tomographic analysis, AdBMP6 produced the most rapid tissue calcification. The ultimate density of ectopic bone formed by AdBMP4 and AdBMP6 was comparable. The current study demonstrates that AdBMP4 and AdBMP6 are more potent than the prototypical osteogenic adenoviral vector AdBMP2 and seem to induce ectopic bone by different mechanisms.

Adenoviridae↗
PubMed2002

[Color Doppler ultrasonographic assessment of the risk of injury to major branch of the middle hepatic vein during laparoscopic cholecystectomy].

OBJECTIVE: To investigate the cause of hemorrhage from the gallbladder bed during laparoscopic cholecystectomy. METHODS: Color Doppler ultrasound was used to examine the cause of venous hemorrhage from the gallbladder bed during laparoscopic cholecystectomy in 1 patient postoperatively and to examine the anatomic relationship between the gallbladder bed and branches of the middle hepatic vein in 91 patients preoperatively. RESULTS: There is a major branch of middle hepatic vein extended close to the gallbladder bed. The branch of the middle hepatic vein was completely adherent to the gallbladder bed in 14 of 91 patients (15.4%). The mean distance between the closest point of the middle hepatic vein and the gallbladder bed is 5.0 +/- 4.6 mm, the mean diameter of this point is 3.2 +/- 1.1 mm. CONCLUSIONS: Patients with large branches of the middle hepatic vein close to the gallbladder bed are at risk of hemorrhage during laparoscopic cholecystectomy and should be identified preoperatively with ultrasound.

Cholecystectomy, Laparoscopic↗
PubMed2002

[Serological investigations on patients with hemolytic uremic syndromes due to enterohemorrhagic Escherichia coli O157:H7 infection].

OBJECTIVE: To investigate the etiological agent of patients with diarrhea followed by acute kidney failure symptoms in China, 1999. METHODS: Western blot was used to detect serum specific antibodies of patients against entero-haemorrhagic Escherichia coli hemolysin (EHEC-Hly) and lipo-polysaccharide of E. coli O157. RESULTS: Twenty-one and 16 of 42 patients showed positive reaction of specific IgG or IgM antibodies against EHEC-Hly respectively. Eleven of 42 serum samples were positive for having both IgG and IgM antibodies while 26 of 42 samples were positive for IgG or IgM. For E. coli O157 LPS test, 24 and 24 of 42 samples showed positive for IgG or IgM antibodies respectively. In 42 samples, 20 were positive for IgG and IgM while 29 were positive for IgG or IgM. CONCLUSIONS: Twenty-two of 42 samples were reacted with EHEC-Hly and E. coli O157 LPS, but 34 of 42 samples were positive for EHEC-Hly or E. coli O157. In combination of western blot results, bacterial isolation clinical symptoms and epidemiological investigation findings, it was reasonable to conclude that this cluster of patients with distinguish clinical symptoms was caused by E. coli O157:H7, which had never been reported in China. Hence serological methods with EHEC-Hly and E. coli O157 LPS are valuable for diagnosis of infections of E. coli O157:H7, when bacterial isolation is failed.

Adult↗
PubMed2002

[Study on diarrhea disease caused by enterohemorrhagic Escherichia coli O157:H7 in Xuzhou city, Jiangsu province in 2000].

OBJECTIVE: To investigate the proportion of hemorrhagic colitis (HC) caused by Escherichia coli O157:H7 in bacterial diarrhea in Xuzhou city, Jiangsu province. METHODS: All stool samples from patients with diarrhea were screened for O157 antigen, using Immuno-gold kits. Positive samples were cultured to detect the existence of pathogens. All of the HC patients confirmed by bacterial isolation and identification were investigated for clinical symptoms and laboratory tests. RESULTS: Of the diarrhea patients identified in Feng county in May, and in Tongshan county of Xuzhou city in June 2000, Jiangsu province 0.98% and 5.89% were caused by Escherichia coli O157:H7 respectively, confirmed by bacteriological isolation and identification of stool samples. At the early phase of hemorrhagic colitis, 18.5% patients had at least one abnormal clinical laboratory test results including protein in urea and increased BUN or creatinine that indicating the possibility of kidney damage. In 27 strains of E. coli O157:H7 isolated from those patients, 13 and 14 were identified as Shiga toxin producing and Shiga-toxin negative E. coli O157:H7 (Stx-positive or Stx-negative) respectively. By analysis of the two groups of patients divided by according to the nature of Shiga toxin, four of 13 patients of Stx-positive group showed positive urea protein. However only 1 of the 13 patients of Stx-negative group was urea protein positive. The decreased Platelets counts were observed in 6 of 13 patients with Stx-positive group, but only in 1 of 14 patients with stx-negative group. These differences were statistically significant. CONCLUSION: HC patients caused by E. coli O157:H7 were commonly seen (up to 5.89%) in Xuzhou city, Jiangsu province. Early laboratory tests should be conducted for HC patients as early as possible in order to find early indictor of kidney failure which was critical for prevention of hemolytic uremic syndrome.

Adolescent↗
PubMed2002

Expression of recombinant adeno-associated virus in the brain of rats with a focal embolic stroke via carotid artery.

OBJECTIVE: To study whether recombinant adeno-associated virus (rAAV) mediated foreign gene, LacZ, could pass the blood brain barrier by intra-carotid artery delivery and express in vivo in ischemic brain of the focal embolic stroke rats to investigate a possibility of delivering foreign gene through carotid artery to treat acute ischemic stroke. METHODS: The carotid artery territory in 41 rats was embolized with or without arterial-like fibrin rich clots to make a model of focal embolic stroke rat. rAAV containing LacZ gene (rAAV-LacZ) was constructed in 293 cells by calcium phosphate cotransfection. The rats were assigned to one of the following treatments: 1 control (without embolism) groups, including PBS treated (n = 6), pLacZ treated (n = 6 ) and rAAV-LacZ treated (n = 6): 2 embolic groups, including embolism + PBS (n =7),embolism + pLacZ (n = 8) and embolism + rAAV-LacZ (n = 8). Brains were cryosectioned and kappa-Gal stain was performed at 2, 4, and 8 weeks, respectively, after transfection, and then infarct volume was measured and the percentage of LacZ staining-positive cells was calculated. RESULTS: In all the control groups and embolism + PBS treated animal, no kappa-Gal staining-positive cells were found, but in embolism + pLacZ (n = 8) and embolism+rAAV-LacZ groups a lot of kappa-Gal staining-positive cells were found. The expression cells were in the tissues around the infarction. The gene expression persisted only nearly four weeks in embolic group with pLacZ. In the embolic group with rAAV-LacZ the expression was very stable during the experiment course (eight weeks) and the percentage of the expressed cells was significantly higher than that of its contralateral areas at the same time points, respectively. CONCLUSIONS: The plasmid vector and rAAV could enter the brain through the ischemia-damaged blood barrier and foreign gene can be expressed in brain. The positive gene expression is mainly in the peripheral areas of the infarction. rAAV as a permanent expression vector may ultimately be used for gene therapy of human ischemia cerebravascular diseases.

Animals↗
PubMed2002

Experiences relating to management of biliary tract complications following liver transplantation in 96 cases.

OBJECTIVE: To investigate best diagnosing methods and therapy for patients with biliary tract complications after liver transplantation and analyze related factors. METHODS: A review was made of data collected from 96 patients, and confirmed by retrospective case notes examination. RESULTS: A total of 94 patients (97 grafts) survived more than 2 days after transplantation; of whom, 92 had an end-to-end biliary anastomosis with a T tube. The average follow-up was 5.8 months (range: 0.3 - 10.2 months). Among the 94 patients, eight (8.5%, 8/94) had complications: leakage during T-tube removal (2 patients), leakage at an earlier stage (2), simultaneous stricture and leak (2) and just stricture (2). Six patients with biliary tract complications had predisposing factors including hepatic artery stenosis (2 patients, including one hepatic artery stenosis combined with severe rejection, hepatic artery thrombosis (3), and donor-recipient bile duct mismatch (1). There was no difference in cold ischemic time. With hepatic artery thrombosis and/or stenosis > 50%, five patients were re-transplanted; without hepatic artery thrombosis and/or stenosis < 50%, three patients required endoscopic stenting and radiological percutaneous drainage of bile collection with or without balloon dilation. All patients survived. CONCLUSIONS: Biliary strictures occur later than leaks after surgery. Without hepatic artery thrombosis and/or stricture, there is no need for surgery; with hepatic artery thrombosis and/or stricture > 50%, re-transplantation is needed as early as possible.

Adult↗
PubMed2002

[Whether the impairment of grafted liver was induced by the inflammatory cells in cold and warm ischemia after transplantation].

OBJECTIVE: To investigate whether the impairment of grafted liver after transplantation was induced by the same inflammatory cells in cold and warm ischemia. METHODS: Male SD rats were divided into two groups randomly, 24 grafted livers in each group were stored for 120 or 240 min at 4 degrees Centigrade Ringer's solution. Also male SD rats were divided into three groups, in which 24 grafted livers in each group were experienced warm ischemia ranged from 90, 120 to 150 min from non-heart-beating donor. The recipients were killed after 1, 3, 6, and 24 hours of transplantation for sample collection. RESULTS: Along with the prolongation of cold and warm ischemia time, the serum ALT and AST levels were increased gradually after transplantation. Light microscopy showed some necroses in hepatocytes after 3 and 6 hours of transplantation in cold ischemia, and some neutrophilic infiltration in sinusoids. There were a large number of hepatocytes necroses after 3, 6 hours of transplantation in warm ischemia from non-heart-beating donor and a lot of lymphocytic infiltration in sinusoids. The findings in electron microscopy were as the same as those found in light microscopy, and the lymphocytes which infiltrated in sinusoids in warm ischemia were identified as T lymphocytes in electron microscopy. CONCLUSIONS: The impairment of grafted livers after transplantation seems to be induced by two different inflammatory cells in cold and warm ischemia, that is, neutrophils mediate the cold ischemia-reperfusion, and T lymphocytes mediate the warm ischemia-reperfusion from non-heart-beating donor.

Alanine Transaminase↗