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Biomedical subjects

Ying Wen

Publications and source records attributed to Ying Wen.

At least 19 recordsLinked to original sources
PubMed2006

Moesin regulates stable microtubule formation and limits retroviral infection in cultured cells.

In a functional screen of mammalian complementary DNA libraries, we identified moesin as a novel gene whose overexpression blocks infection by murine leukemia viruses and human immunodeficiency virus type 1 in human and rodent lines, before the initiation of reverse transcription. Knockdown of moesin by RNA interference resulted in enhanced infection, suggesting that even the endogenous basal levels of moesin in rat fibroblasts are sufficient to limit virus infection. Moesin acts as a crosslinker between plasma membrane and actin filaments, as well as a signal transducer in responses involving cytoskeletal remodeling. Moesin overexpression was found to downregulate the formation of stable microtubules, whereas knockdown of moesin increased stable microtubule formation. A virus-resistant mutant cell line also displayed decreased stable microtubule levels, and virus-sensitive revertants recovered from the mutant line showed restoration of the stable microtubules, suggesting that these cytoskeletal networks play an important role in early post-entry events in the retroviral lifecycle. Together, these results suggest that moesin negatively regulates stable microtubule networks and is a natural determinant of cellular sensitivity to retroviral infection.

Animals↗
PubMed2006

Diagnosis and treatment of small intestinal bleeding: retrospective analysis of 76 cases.

AIM: To investigate the causes of small intestinal bleeding as well as its diagnosis and therapeutic approaches. METHODS: A retrospective analysis was conducted according to the clinical records of 76 patients with small intestinal bleeding admitted to our hospital in the past 5 years. RESULTS: In these patients, tumor was the most frequent cause of small intestinal bleeding (37/76), followed by Mecke's diverticulum (21/76), angiopathy (15/76) and ectopic pancreas (3/76). Of the 76 patients, 21 were diagnosed by digital subtraction angiography, 13 by barium and air double contrast X-ray examination of the small intestine, 11 by 99mTc-sestamibi scintigraphy of the abdominal cavity, 6 by enteroscopy of the small intestine, 21 by laparoscopic laparotomy, and 4 by exploratory laparotomy. Although all the patients received surgical treatment, most of them (68/76) received part enterectomy covering the diseased segment and enteroanastomosis. The follow-up time ranged from 1 year to 5 years. No case had recurrent alimentary tract bleeding or other complications. CONCLUSION: Tumor is the major cause of small intestinal bleeding followed by Meckel's diverticulum and angiopathy. The main approaches to definite diagnosis of small intestinal bleeding include digital subtraction angiography, 99mTc-sestamibi scintigraphy of the abdominal cavity, barium and air double contrast X-ray examination of the small intestine, laparoscopic laparotomy or exploratory laparotomy. Part enterectomy covering the diseased segment and enteroanastomosis are the most effective treatment modalities for small intestinal bleeding.

Adolescent↗
PubMed2006

Application of laparoscopy in diagnosis and treatment of massive small intestinal bleeding: report of 22 cases.

AIM: To investigate the diagnostic and therapeutic value of laparoscopy in patients with massive small intestinal bleeding. METHODS: Twenty-two patients with massive small intestinal bleeding and hemodynamic alteration underwent laparoscopic laparotomy in our unit from December 2002 to April 2005. Post pathologic sites were found, laparoscopy- or laparoscopy-assisted part small intestinal resection including pathologic intestinal site and enteroanastomosis was performed in all these patients. RESULTS: The bleeding sites were successfully detected by laparoscopy in all these 22 patients. Massive small intestinal bleeding was caused by jejunum benign stromal tumor in 8 cases, by jejunum potential malignant stromal tumor in 5 cases, by jejunum malignant stromal tumor in 1 case, by Mechel's diverticulum in 5 cases, by small intestinal vascular deformity in 2 cases, and by ectopic pancreas in 1 case. A total of 16 patients underwent laparoscopy-assisted enterectomy and enteroanastomosis of small intestine covering the diseased segment and 6 patients received enterectomy of the diseased segment under laparoscope. No surgical complications occurred and the outcome was satisfactory. CONCLUSION: Laparoscopy in diagnosis and treatment of massive small intestinal bleeding is noninvasive with less pain, short recovery time and definite therapeutic efficacy.

Adolescent↗
PubMed2006

Construction of ivermectin producer by domain swaps of avermectin polyketide synthase in Streptomyces avermitilis.

Ivermectin, 22, 23-dihydroavermectin B1, is commercially important in human, veterinary medicine, and pesticides. It is currently synthesized by chemical reduction of the double bond between C22 and C23 of avermectins B1, which are a mixture of B1a (>80%) and B1b (<20%) produced by fermentation of Streptomyces avermitilis. The cost of ivermectin is much higher than that of avermectins B1 owing to the necessity of region-specific hydrogenation at C22-C23 of avermectins B1 with rhodium chloride as the catalyst for producing ivermectin. Here we report that ivermectin can be produced directly by fermentation of recombinant strains constructed through targeted genetic engineering of the avermectin polyketide synthase (PKS) in S. avermitilis Olm73-12, which produces only avermectins B and not avermectins A and oligomycin. The DNA region encoding the dehydratase (DH) and ketoreductase (KR) domains of module 2 from the avermectin PKS in S. avermitilis Olm73-12 was replaced by the DNA fragment encoding the DH, enoylreductase, and KR domains from module 4 of the pikromycin PKS of Streptomyces venezuelae ATCC 15439 using a gene replacement vector pXL211. Twenty-seven of mutants were found to produce a small amount of 22, 23-dihydroavermectin B1a and avermectin B1a and B2a by high performance liquid chromatography and liquid chromatography mass spectrometry analysis. This study might provide a route to the low-cost production of ivermectin by fermentation.

Genetic Engineering↗
PubMed2005

Expression and function of 5-HT4 receptors in the mouse enteric nervous system.

The aim of the current study was to identify enteric 5-HT(4) splice variants, locate enteric 5-HT(4) receptors, determine the relationship, if any, of the 5-HT(4) receptor to 5-HT(1P) activity, and to ascertain the function of 5-HT(4) receptors in enteric neurophysiology. 5-HT(4a), 5-HT(4b), 5-HT(4e), and 5-HT(4f) isoforms were found in mouse brain and gut. The ratio of 5-HT(4) expression to that of the neural marker, synaptophysin, was higher in gut than in brain but was similar in small and large intestines. Submucosal 5-HT(4) expression was higher than myenteric. Although transcripts encoding 5-HT(4a) and 5-HT(4b) isoforms were more abundant, those encoding 5-HT(4e) and 5-HT(4f) were myenteric plexus specific. In situ hybridization revealed the presence of transcripts encoding 5-HT(4) receptors in subsets of enteric neurons, interstitial cells of Cajal, and smooth muscle cells. IgY antibodies to mouse 5-HT(4) receptors were raised, affinity purified, and characterized. Nerve fibers in the circular muscle and the neuropil in ganglia of both plexuses were highly 5-HT(4) immunoreactive, although only a small subset of neurons contained 5-HT(4) immunoreactivity. No 5-HT(4)-immunoreactive nerves were detected in the mucosa. 5-HT and 5-HT(1P) agonists evoked a G protein-mediated long-lasting inward current that was neither mimicked by 5-HT(4) agonists nor blocked by 5-HT(4) antagonists. In contrast, the 5-HT(4) agonists renzapride and tegaserod increased the amplitudes of nicotinic evoked excitatory postsynaptic currents. Enteric neuronal 5-HT(4) receptors thus are presynaptic and probably exert their prokinetic effects by strengthening excitatory neurotransmission.

Alternative Splicing↗
PubMed2005

Aspergillus parasiticus cyclase catalyzes two dehydration steps in aflatoxin biosynthesis.

In the aflatoxin biosynthetic pathway, 5'-oxoaverantin (OAVN) cyclase, the cytosolic enzyme, catalyzes the reaction from OAVN to (2'S,5'S)-averufin (AVR) (E. Sakuno, K. Yabe, and H. Nakajima, Appl. Environ. Microbiol. 69:6418-6426, 2003). Interestingly, the N-terminal 25-amino-acid sequence of OAVN cyclase completely matched an internal sequence of the versiconal (VHOH) cyclase that was deduced from its gene (vbs). The purified OAVN cyclase also catalyzed the reaction from VHOH to versicolorin B (VB). In a competition experiment using the cytosol fraction of Aspergillus parasiticus, a high concentration of VHOH inhibited the enzyme reaction from OAVN to AVR, and instead VB was newly formed. The recombinant Vbs protein, which was expressed in Pichia pastoris, showed OAVN cyclase activity, as well as VHOH cyclase activity. A mutant of A. parasiticus SYS-4 (= NRRL 2999) with vbs deleted accumulated large amounts of OAVN, 5'-hydroxyaverantin, averantin, AVR, and averufanin in the mycelium. These results indicated that the cyclase encoded by the vbs gene is also involved in the reaction from OAVN to AVR in aflatoxin biosynthesis. Small amounts of VHOH, VB, and aflatoxins also accumulated in the same mutant, and this accumulation may have been due to an unknown enzyme(s) not involved in aflatoxin biosynthesis. This is the first report of one enzyme catalyzing two different reactions in a pathway of secondary metabolism.

Aflatoxins↗
PubMed2005

Function of the cypX and moxY genes in aflatoxin biosynthesis in Aspergillus parasiticus.

The pathway oxoaverantin (OAVN) --> averufin (AVR) --> hydroxyversicolorone (HVN) --> versiconal hemiacetal acetate (VHA) is involved in aflatoxin biosynthesis, and the cypX and moxY genes, which are present in the aflatoxin gene cluster, have been previously suggested to be involved in this pathway. To clarify the function of these two genes in more detail, we disrupted the genes in aflatoxigenic Aspergillus parasiticus NRRL 2999. The cypX-deleted mutant lost aflatoxin productivity and accumulated AVR in the mycelia. Although this mutant converted HVN, versicolorone (VONE), VHA, and versiconol acetate (VOAc) to aflatoxins in feeding experiments, it could not produce aflatoxins from either OAVN or AVR. The moxY-deleted mutant also lost aflatoxin productivity, whereas it newly accumulated HVN and VONE. In feeding experiments, this mutant converted either VHA or VOAc to aflatoxins but did not convert OAVN, AVR, HVN, or VONE to aflatoxins. These results demonstrated that cypX encodes AVR monooxygenase, catalyzing the reaction from AVR to HVN, and moxY encodes HVN monooxygenase, catalyzing a Baeyer-Villiger reaction from HVN to VHA as well as from VONE to VOAc. In this work, we devised a simple and rapid method to extract DNA from many fungi for PCR analyses in which cell disruption with a shaker and phenol extraction were combined.

Aflatoxins↗
PubMed2005

[Oligonucleotide microarray for human immunodeficiency virus detection].

OBJECTIVE: To develop an oligonucleotide microarray for fast detection of human immunodeficiency virus (HIV). METHODS: With complete genome sequence of HIV-1 subtype B (U26942) as the target sequence and bioinformatics software such as DNAClub, Oligo6.0, BLAST, Alignment, oligonucleotide probes of high specificity with identical length and similar melting temperature (T(m)) were designed and synthesized. Oligonucleotide microarray was prepared using Cartesian Microarrayer. Using the plasmids of HIV-1 subtype B(U26942), C(U46016), F(AF075703), G(AF061640) and restriction display technique, Cy3-labeled HIV DNA fragments were amplified and the hybridization results were scanned and analyzed with Array-Pro. RESULTS AND CONCLUSION: Twenty-two optimized oligonucleotide microarray probes were obtained and used to prepare the oligonucleotide microarray for further screening studies. The microarray prepared significantly enhanced the sensitivity, reliability and speed of DNA assay, and possesses the potential for application in clinical setting.

Base Sequence↗
PubMed2005

Regulation of microtubules by Rho GTPases in migrating cells.

Microtubules (MTs) contribute to cell polarization and migration, but the molecular mechanism involved are unknown. We have explored signalling pathways that generate specific changes in MTs arrays in wounded monolayers of fibroblasts. In earlier work, we found that Rho GTPase and its effector mDia, stimulate selective MT stabilization in the lamella, whereas Cdc42 and the MT motor protein dynein regulate MT organizing centre (MTOC) reorientation towards the leading edge. We have now found that the MT tip proteins EB1 and adenomatous polyposis coli protein (APC) function with mDia to stabilize MTs and interact directly with mDia. EB1, APC and mDia localize to the ends of stabilized MTs suggesting that they may contribute to capping of these MTs. Models of MTOC reorientation suggest that the MTOC moves in front of the nucleus by dynein pulling on MTs. In contrast, we find by directly imaging MTOC reorientation that the nucleus moves rearward while the MTOC remains stationary. Rearward nuclear movement is coupled to retrograde actin-myosin flow and is regulated by Cdc42 and its effector myotonic dystrophy kinase-related Cdc42-binding kinase. Dynein is not involved in nuclear movement, but is essential to maintain the MTOC at the cell centroid. These results show that there are two Cdc42 pathways that regulate MTOC reorientation.

Animals↗
PubMed2004

The co-activator CREB-binding protein participates in enhancer-dependent activities of bicoid.

Bicoid (Bcd) is a transcriptional activator required for early embryonic patterning in Drosophila. Despite extensive studies, it currently remains unclear how Bcd activates transcription and what proteins participate in its activation process. In this report, we describe experiments to analyze the role of the Drosophila co-activator dCBP in Bcd-mediated activation. In Drosophila S2 cells, the Bcd activity is increased by the co-transfection of plasmids expressing dCBP and reduced by double-stranded RNA-mediated interference against dCBP. We further show that Bcd and dCBP can interact with each other and that Bcd-interacting domains of dCBP can cause dominant negative effects on Bcd activity in S2 cells. Our comparison of two Bcd-responsive enhancers, hunchback (hb) and knirps (kni), reveals a differential role of dCBP in facilitating Bcd activation. A dCBP mutant defective in its histone acetyltransferase activity exhibits a reduced, but not abolished, co-activator function for Bcd. Our chromatin immunoprecipitation experiments show that dCBP can increase not only the occupancy of Bcd itself at the enhancers but also the recruitment of general transcription factors to the promoter. Together, these experiments suggest that dCBP is an enhancer-dependent co-activator of Bcd, facilitating its activation through multiple mechanisms.

Acetyltransferases↗
PubMed2004

EB1 and APC bind to mDia to stabilize microtubules downstream of Rho and promote cell migration.

Lysophosphatidic acid (LPA) stimulates Rho GTPase and its effector, the formin mDia, to capture and stabilize microtubules in fibroblasts. We investigated whether mammalian EB1 and adenomatous polyposis coli (APC) function downstream of Rho-mDia in microtubule stabilization. A carboxy-terminal APC-binding fragment of EB1 (EB1-C) functioned as a dominant-negative inhibitor of microtubule stabilization induced by LPA or active mDia. Knockdown of EB1 with small interfering RNAs also prevented microtubule stabilization. Expression of either full-length EB1 or APC, but not an APC-binding mutant of EB1, was sufficient to stabilize microtubules. Binding and localization studies showed that EB1, APC and mDia may form a complex at stable microtubule ends. Furthermore, EB1-C, but not an APC-binding mutant, inhibited fibroblast migration in an in vitro wounding assay. These results show an evolutionarily conserved pathway for microtubule capture, and suggest that mDia functions as a scaffold protein for EB1 and APC to stabilize microtubules and promote cell migration.

Adenomatous Polyposis Coli Protein↗
PubMed2004

Cortical control of microtubule stability and polarization.

In both dividing and interphase cells, microtubules are remodeled in response to signal transduction pathways triggered by a variety of stimuli. Members of the Rho family of small GTPases have emerged as key intermediates in transmitting signals to cortical factors that mediate capture of dynamic microtubules at specific sites. The specificity of cortical capture appears to be controlled by microtubule tip proteins and cortical receptors that bind these proteins. Recent studies suggest that some of the proteins interacting with microtubule tips behave as bridging proteins between the microtubule tip proteins and their cortical receptors. Such bridging proteins may enhance cortical capture of microtubules directly or indirectly through interactions with the actin cytoskeleton.

Animals↗
PubMed2004

Pancreatic enzymes in the gut contributing to lung injury after trauma/hemorrhagic shock.

OBJECTIVE: To examine whether pancreatic proteolytic enzymes involve in lung injury induced by trauma/hemorrhagic shock (T/HS). METHODS: Male Sprague-Dawley rats received intraluminal or intravenous pancreatic serine protease inhibitor, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfate (ANGD) during laparotomy (trauma), and were subjected to 90 minutes of T/HS or trauma-sham shock (T/SS). Degree of lung injury was assessed 3 hours after resuscitation with Ringer's lactate solution. RESULTS: Lung permeability, pulmonary myeloperoxidase levels and the ratio of bronchoalveolar lavage fluid protein to plasma protein increased after T/HS, and significantly decreased in intraluminal-ANGD treated but not in intravenous-ANGD treated rats. Histological analysis demonstrated fewer injured villi in the intraluminal-ANGD treated rats compared with those in the control rats. Linear regression analysis revealed that the percentage of injured ileal mucosal villi directly related to pulmonary polymorphic neutrophil sequestration and lung permeability to Evans blue dye. CONCLUSIONS: Pancreatic proteolytic enzymes in the ischemic gut may be important toxic factors contributing to lung injury after T/HS.

Analysis of Variance↗
PubMed2004

[A study on the factors influencing insulin resistance in children and adolescents].

OBJECTIVE: To explore the factors influencing insulin resistance in children with different nutritional status during pubertal development. METHODS: Three hundred children with simple obese aged 7 to 17 years, and 300 normal healthy children and 300 children with malnutrition, matched for age (+/- 3 months) and height (+/- 2 cm), were selected. Fasting serum levels of leptin, insulin, glucose, total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDL-C) and high density lipoprotein-cholesterol (HDL-C) were measured for them. RESULTS: Levels of fasting serum insulin in obese children, except for boys at Tanner stage I and girls at Tanner stage II, were higher than those in normal and malnutrition children (P < 0.01). Average serum level of leptin in obese boys and girls at varied Tanner stages was higher than that in normal children, and higher in normal children than that in children with malnutrition (P<0.01). Serum level of TG in obese children [(1.53 +/- 0.13) mmol/L] was higher than that in normal ones [(1.12 +/- 0.10) mmol/L] and in children with malnutrition [(1.03 +/- 0.09) mmol/L]. There was no significant difference in levels of fasting blood glucose and other blood lipids between the three groups of children. Insulin sensitivity decreased with pubertal development and its index reversely correlated with Tanner stage and serum level of leptin (r=-0.27 and -0.36, respectively, P<0.01). CONCLUSION: Obesity (BMI), serum level of leptin and pubertal development were independent risk factors for insulin resistance in children aged 7 to 17 years.

Adolescent↗
PubMed2004

[Role of pancreatic enzymes in gut injury secondary to trauma/hemorrhagic shock in rats].

OBJECTIVE: To test the hypothesis that pancreatic digestive enzymes are involved in trauma/hemorrhagic shock (T/HS)-induced intestinal injury. METHODS: Male Sprague-Dawley rats were given pancreatic enzyme inhibitor (6-amidino-2 -naphthyl p-guanidinobenzoate dimethanesulfonate, ANGD) intraluminally or intravenously after laparotomy (trauma), and then subjected to 90 min of hemorrhagic shock or sham shock. Intestinal injury was assessed 3 h after resuscitation with Ringer's lactate solution. RESULTS: Histological analysis demonstrated fewer injured villi in shock rats with intraluminal ANGD treatment than in those with intravenous ANGD administration and control shock rats. Furthermore, intestinal intraluminal perfusion of Ringer's lactate solution without ANGD produced a certain degree of protection against T/HS-induced intestinal injury, as compared with the rats without perfusion. CONCLUSION: Pancreatic proteolytic enzymes in ischemic gut may serve as important toxic factors contributing to gut injury following T/HS.

Animals↗
PubMed2003

[Tumor necrosis factor-alpha enhances the effect of endothelin on renal vasoconstriction in isolated perfused rat kidney].

OBJECTIVE: To explore the role of tumor necrosis factor-alpha (TNF-alpha) in the pathogenesis of hepatorenal syndrome. METHODS: By isolated perfused kidney technique, rat kidneys were perfused at a constant flow. Changes in perfusion pressure (mmHg) were consecutively measured with multi-functional physiology recorder. After TNF-alpha or heparin treated 90 minutes, the perfusion pressure stimulated by endothelin-1 (ET-1) was detected. RESULTS: TNF-alpha and heparin didn't modify the baseline perfusion pressure. When ET-1 was added at 2 nmol/L, the perfusion pressures increased to (47+/-9) mmHg, (97+/-36) mm Hg and (11+/-6) mm Hg in control, TNF-alpha and heparin (10mg/L) treated group, respectively, which were different among the three groups (t>or=3.811, P<0.01). No pathological damages were found in kidney tissues from all the groups after being stained with hematoxylin/eosin. CONCLUSION: TNF-alpha plays an important role in the pathogenesis of hepatorenal syndrome by promoting renal vasoconstriction.

Animals↗