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Bin Xu

Publications and source records attributed to Bin Xu.

105 records · Page 6Linked to original sources
PubMed2002

A cavity-forming mutation in insulin induces segmental unfolding of a surrounding alpha-helix.

To investigate the cooperativity of insulin's structure, a cavity-forming substitution was introduced within the hydrophobic core of an engineered monomer. The substitution, Ile(A2)-->Ala in the A1-A8 alpha-helix, does not impair disulfide pairing between chains. In accord with past studies of cavity-forming mutations in globular proteins, a decrement was observed in thermodynamic stability (DeltaDeltaG(u) 0.4-1.2 kcal/mole). Unexpectedly, CD studies indicate an attenuated alpha-helix content, which is assigned by NMR spectroscopy to selective destabilization of the A1-A8 segment. The analog's solution structure is otherwise similar to that of native insulin, including the B chain's supersecondary structure and a major portion of the hydrophobic core. Our results show that (1) a cavity-forming mutation in a globular protein can lead to segmental unfolding, (2) tertiary packing of Ile(A2), a residue of low helical propensity, stabilizes the A1-A8 alpha-helix, and (3) folding of this segment is not required for native disulfide pairing or overall structure. We discuss these results in relation to a hierarchical pathway of protein folding and misfolding. The Ala(A2) analog's low biological activity (0.5% relative to the parent monomer) highlights the importance of the A1-A8 alpha-helix in receptor recognition.

Alanine↗
PubMed2002

Structural, biochemical, and expression analysis of two distinct insulin-like growth factor I receptors and their ligands in zebrafish.

We have cloned and characterized cDNAs encoding the zebrafish IGF ligands and receptors. Sequence comparison showed that the primary structures of zebrafish IGF-I, IGF-II, and IGF-I receptors (IGF-IRs) have been highly conserved in vertebrates. In contrast to the presence of a single IGF-IR gene in mammals, two distinct IGF-IR genes, termed igf-1ra and igf-1rb, were found in zebrafish. Structural and phylogenetic analyses indicated that both genes are orthologous to the human igf-1r gene. Immunoprecipitation studies with specific antibodies showed that both IGF-IR genes are expressed and both receptors bind to IGFs and des(1-3)IGF-I, but not to insulin. The spatio-temporal expression patterns of the two IGF-IRs and their ligands were determined using a combination of RT-PCR, whole mount in situ hybridization, and immunocytochemistry. Transcripts for both IGF-I and -II mRNAs were found throughout embryogenesis in a ubiquitous manner. In adult tissues, IGF-I mRNA was more abundant in liver and testis, and its level was increased after GH treatment, whereas IGF-II mRNA was not regulated by GH. IGF-IRa and IGF-IRb mRNAs and proteins were expressed in overlapping spatial domains, but exhibited distinct temporal expression patterns. In particular, the relative level of IGF-IRa mRNA was low during early embryogenesis and increased in the hatched larva, whereas the situation was reversed for IGF-IRb mRNA. In adult zebrafish, the overall tissue distribution patterns of the two IGF-IRs were similar, but there were differences in their cellular localization and relative abundance in defined cells/regions. The differential expression pattern of IGF-IRa and IGF-IRb suggest that they may play distinct roles in regulating the growth and development of zebrafish.

Amino Acid Sequence↗
PubMed2002

Study on the function of pharynx upper esophageal sphincter in globus hystericus.

AIM: Globus pharyngeus is not an uncommon symptom. Presently, its unclear dated pathophysiology remains unclear and the disease can not be evaluated correctly with routine diagnostic methods. The objective of this study is to establish the normal values of pharyngeal and UES pressure, pharyngeal transit time in healthy volunteers and to compare the differences between healthy volunteers and patients with globus pharyngeus. METHODS: Twenty-four healthy volunteers and thirty-two patients clinically diagnosed as globus pharyngeus entered the study. Pressures of pharynx and UES were measured. Pharyngeal transit time was measured by videofluoroscopic procedure. RESULTS: Normal pressure of pharynx, and normal resting pressure of UES were 157.81+/-63.86 mmHg and 68.33+/-37.56 mmHg, respectively. The corresponding values in the patients were 175.50+/-93.47 mmHg and 71.38+/-41.42 mmHg. The pharyngeal transit time was 1.44+/-0.30 s in normal control group, among them there were 4 cases with stasis of barium in the valleculae and one in the piriform sinus. No laryngeal penetration or aspiration was found. In the patient group, the pharyngeal transit time was 1.37+/-0.41 s, among them there were 6 cases with stasis of barium in the valleculae and 5 in the piriform sinus. 9 cases had laryngeal penetration and 2 had aspiration. There were no statistical differences of pressures of pharynx, UES and the pharyngeal transit time between the two groups. But there was an association between laryngeal penetration and globus pharyngeus. CONCLUSION: Radiographic examination of the pharynx show specific findings of pharyngeal dysfunction in patients with globus pharyngeus. UES pressure is normal in most patients. Hence, we find no role for UES hypertonicity as an etiologic factor in globus pharyngeus.

Adult↗
PubMed2002

[Endovascular intervention versus traditional bypass for treatment of Budd-Chiari syndrome].

OBJECTIVE: To retrospectively compare combined endovascular intervension with traditional bypass operation for the treatment of Budd-Chiari syndrome (BCS). METHODS: From July 1989 to June 2001, 49 patients undergoing surgery for BCS were studied. 32 operations were performed by traditional bypass (from superior mesenteric vein or inferior vena cava to right auricle), and 17 by combined endovascular operation. RESULTS: The data demonstrated a high incidence of perioperative complications, longer hospital stay, and expensive cost in the former group than in the latter group (P < 0.01). The mid-term effects were significantly better in the latter than in the former (P < 0.05). Severe complications occurred in the bypass group included hepatoencephalopathy, obtinacy ascites, cardiac dysfunction, and embolization of vascular grafts. CONCLUSIONS: Combined endovascular intervention and shunting are the treatment of choice for BCS, with different combination according to its clinical type. This approach is simple, safe, effective, and economic.

Adult↗
PubMed2002

[Spatial heterogeneity of grassland pattern under grazing and forage condition].

Spatial heterogeneity and spatial autocorrelation of grassland pattern under grazing and forage condition were studied using semivariance analysis and fractal method. The results indicate that vegetation patterns are scale-dependent. Spatial heterogeneity and spatial autocorrelation of foraged grassland are more complex than grazed grassland and have more scale regions which determined by different fractal characteristics. Spatial autocorrelation of species diversity on foraged grassland was weaker, in another word, gradient of species diversity(beta-diversity) was smaller. Spatial heterogeneity of grazed grassland was simplified by grazing, because topographical variation was partly wiped out.

China↗
PubMed2002

[Clinical characteristics and diagnosis of Pneumocystis carinii pneumonia (PCP) in patients with the acquired immunodeficiency syndrome (AIDS)].

OBJECTIVE: To explore the clinical characteristics and the diagnostic methods for PCP in patients with AIDS. METHODS: Twelve cases of AIDS associated PCP confirmed by sputum polymerase chain reaction (PCR) were analyzed. RESULTS: Tuberculosis was found in 4 cases and pneumonia in 1 case of PCP. Sputum PCR was positive in all the 12 cases, of them blood PCR was positive in 9, Gomori methenamine silver stain (GMS) positive in 5 and Giemsa stain positive in 6 cases. The CD(4)(+) lymphocyte count was (5 approximately 155) x 10(6)/L, with a mean of (51 +/- 48) x 10(6)/L; the number of CD(4)(+) cells less than 100 x 10(6)/L in 10 cases (83%) with 9 cases (75%) less than 50 x 10(6)/L. The CD(4)(+)/CD(8)(+) ratio was 0.01 approximately 0.29. CONCLUSIONS: PCP was common in patients with advanced AIDS and often co-infected with other opportunistic infections such as tuberculosis. A diagnosis of PCP should be considered if sputum PCR is positive and typical clinical manifestations are present in patients with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed2002

A new echocardiographic system for assessment of epicardial and intramyocardial coronary flow in a swine model.

OBJECTIVE: To visualize epicardial and intramyocardial coronary blood flow by using a noninvasive echocardiography system. METHODS: In five juvenile swines, coronary flow imaging was used to visualize the different segments of epicardial coronary and intramyocardial arteries. Pulsed-Doppler spectrums were recorded and analyzed. The left anterior descending artery (LAD) and intramyocardial coronary blood flow signals were recorded at baseline and during dipyridamole administration. RESULTS: Epicardial and intramyocardial coronary arteries could be visualized by coronary flow imaging. The systolic component of coronary flow in the right coronary artery (RCA) was greater than in the LAD. The intramyocardial blood flow was characterized by persistent retrograde blood flow velocity during systole. Vasodilation with dipyridamole produced exaggerated differences in the phasic pattern of coronary blood flow in epicardial and intramyocardial vessels. CONCLUSION: Color Doppler coronary flow imaging provides a noninvasive method to study the coronary blood flow.

Animals↗
PubMed1998

Expression of alpha fetoprotein messenger RNA in BEL-7404 human hepatoma cells and effect of L-4 oxalysine on the expression.

AIM:To investigate alpha-fetoprotein (AFP) mRNA expression in BEL-7404 human hepatoma cells and the effect of L-4-oxalysine (OXL) on the expression.METHODS: Bel-7404 human hepatoma cells were maintained in RPMI 1640 media.Human AFP cDNA probe was labelled with digoxigenin-11-dUTP by the random primer labelling method. The expression of AFP mRNA in Bel-7404 cells was determined by an in situ hybridization technique with digoxigenin-labelled human AFP cDNA probe. The positive intensities of AFP mRNA in cells were analyzed by microspectrophotometer and expressed as absorbance at 470nm. For the experiment with OXL, cells were incubated with various concentrations of the agent for 72h.RESULTS:Essentially all the hepatoma cells contained AFP mRNA in the cytoplasm,although in various amounts. The specificity of the hybridization reaction was confirmed by control experiments in which the use of Rnase-treated BEL-7404 cells, non-AFP producing cells (HL-60 human leukemia cells) or a nonspecific cDNA probe resulted in negative hybridization. When the cells were treated with OXL (25, 50mg/L), the content of AFP mRNA in the cytoplasm was decreased with the inhibition percentages of 34.3% and 70.1%, respectively (P< 0.05).CONCLUSION:AFP mRNA was expressed in BEL-7404 human hepatoma cells and OXL suppressed AFP mRNA expression in the cells.

Journal Article↗
PubMedDate not supplied

MRI of gynecological neoplasm.

MRI is multiplanar, has large field of view, superior contrast resolution and no known adverse effect on the reproductive potential of ovaries. It is useful for characterizing solid, cystic or necrotic tissue, blood and fat. Contrast-enhanced MRI is also a comprehensive examination of the entire pelvis including lymph nodes, peritoneum, pelvic sidewalls, bone and muscles. It provides information about areas difficult to assess surgically, can refine staging classification, assists in planning surgery or radiotherapy and may be more cost-effective by limiting use of surgery. This is a pictorial essay of MRI assessment of female pelvic neoplasm.

Contrast Media↗
PubMedDate not supplied

Contextual influences on the directional responses of tectal cells in pigeons.

Contrary to the traditional view that receptive fields are limited in spatial extent, recent studies have indicated that the response of neurons to a local stimulus within the receptive field can be modulated by stimulation of the surrounding region. Here we quantified the nature of these contextual effects on visual motion responses of neurons in the pigeon's optic tectum using standard extracellular recording techniques. All of the cells tested responded well to a test spot moving across their receptive fields. When a background pattern was moved in the same or in a similar direction as that of the test spot, the responses of most deep tectal neurons to the test spot were maximally inhibited. Movement of the background in the opposite or near opposite direction produced minimal inhibition or even facilitation. For some deep tectal neurons, this directionally selective modulation by the moving background was maintained when the background motion was paired with different movement directions of the test spot (including both the preferred and least preferred directions). Thus, this selectivity for opposing motion was independent of the absolute direction of either the test spot or the background, a finding which is consistent with the results reported by Frost and Nakayama (1983), although they did not include all test spot directions. For some other neurons, identified here for the first time, the background movement selectively modulated the response only when the test spot moved in the neuron's preferred directions. These neurons lost selectivity for opposing motion when the test spot moved in nonpreferred directions. The significance of these contextual effects on the motion response of tectal neurons may be related to how the brain distinguishes self-induced motion from object motion and segregates figure from ground.

Animals↗
PubMedDate not supplied

Hepatocellular carcinoma with bile duct thrombi: analysis of surgical treatment.

BACKGROUND/AIMS: To summarize the experience of surgical intervention for hepatocellular carcinoma with bile duct thrombi, and to evaluate the influence on prognosis. METHODOLOGY: From 1994 to 2002, 15 patients with hepatocellular carcinoma and bile duct thrombi who underwent surgical intervention were retrospectively analyzed. The operative procedures included hepatectomy with removal of bile duct thrombi (n=7), hepatectomy combined with extrahepatic bile duct resection (n=4), thrombectomy through choledochotomy (n=3), and piggyback orthotopic liver transplantation (n=1). RESULTS: The 1- and 3-year survival rates were 73.3% and 40%, respectively. Two patients survived over 5 years. There were no significant differences in the survival rates between patients with and without obstructive jaundice (P>0.05). The survival rate of patients with portal vein invasion was significantly lower than for those without portal vein invasion (P<0.05). CONCLUSIONS: Surgical intervention was effective for patients with hepatocellular carcinoma and bile duct thrombi. Operation for recurrent intrahepatic tumor can prolong the survival period. Liver transplantation is a new operative procedure worthy of investigation.

Adult↗
PubMedDate not supplied

Treatment of advanced gastric cancer by chemotherapy combined with autologous cytokine-induced killer cells.

The effects of autologous cytokine-induced killer (CIK) (CD3+CD56+) cells together with chemotherapy were investigated in patients who suffered from advanced gastric cancers (stage IV). Fifty-seven patients were divided into two groups: chemotherapy plus CIK biotherapy and chemotherapy alone. CIK cells were induced from autologous peripheral blood mononuclear cells in vitro and separated by flow cytometry and then transfused into the patients. The T-lymphocyte subgroups (CD3+, CD4+ or CD8+), CIK cells and NK cells (CD3-CD56+) were separated and determined by flow cytometry and the serum levels of MG7-Ag, CA72-4, CA19-9 and CEA were determined by ELISA or ECLIA. It was demonstrated that the cytotoxic activity of CIK cells reached a maximum between days 14 to 21 (68.7+/-10.9% and 65.3+/-10.4%, respectively). The amounts of CIK cells were gradually increased from day 0 to day 21 and slightly decreased in the further incubations. Thereafter, the CIK cells on days 14 to 21 (with the highest population of CIK cells) transfused back to the patients. The serum levels of the tumor markers were significantly decreased, the host immune function was increased and the short-term curative effect as well as the quality of life (QOL) were improved in the patients treated by chemotherapy plus CIK cells compared to the patients treated by chemotherapy alone. Moreover, the 2-year life-span was prolonged in the group treated by chemotherapy plus CIK cells compared to the group treated with chemotherapy alone. It is concluded that chemotherapy plus CIK cells has obvious benefits for patients who suffer from advanced gastric cancers.

Adult↗