Biomedical subjects

Bin Hu

Publications and source records attributed to Bin Hu.

At least 91 records · Page 5Linked to original sources

PubMed2003

Low-temperature electrothermal vaporization of thenoyltrifluoroacetone complex of Sc(III) and Y(III) for sample introduction in an inductively coupled plasma atomic emission spectrometry, and their determination in biological samples.

A new method for inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of trace Sc and Y, based on gaseous compound introduction into the plasma as their thenoyltrifluoroacetone (TTA) complexes by electrothermal vaporization was developed. Using the reagent TTA as chemical modifier can not only enhance the analytical signals, but also reduce the vaporization temperature. At a temperature of 1,000 degrees C the trace Sc and Y can be vaporized completely into ICP. The factors affecting the formation of the chelate and its vaporization behavior, such as drying time, vaporization temperature/time, reaction medium and the amount of TTA, were investigated in detail. Under the optimized conditions (drying temperature/time 100 degrees C/10 s, vaporization temperature/time 1,000 degrees C/4 s), the limits of detection for Sc and Y were 19 pg and 34 pg (3sigma), respectively, and the relative standard deviations for Sc and Y were 4.2% (cSc=0.2 microg mL(-1); n=7) and 2.6% (cY=0.5 microg mL(-1); n=7). The linear ranges of the calibration graphs cover three orders of magnitude. The method was applied to the analysis of the biological reference materials (GBW 07602, bush branches and leaves; GBW 07604, poplar leaves), and the results obtained were in good agreement with the certified values.

Electrochemistry↗

PubMed2003

Soluble glycoprotein VI dimer inhibits platelet adhesion and aggregation to the injured vessel wall in vivo.

Platelet-collagen interactions play a fundamental role in the process of arterial thrombosis. The major platelet collagen receptor is the glycoprotein VI (GPVI). Here, we determined the effects of a soluble dimeric form of GPVI on platelet adhesion in vitro and in vivo. We fused the extracellular domain of GPVI with the human immunoglobulin Fc domain. The soluble dimeric form of GPVI (GPVI-Fc) specifically bound to immobilized collagen. Binding of GPVI-Fc to collagen was inhibited competitively by soluble GPVI-Fc, but not control Fc lacking the external GPVI domain. GPVI-Fc inhibited the adhesion of CHO cells that stably express human GPVI and of platelets on collagen and attenuated thrombus formation under shear conditions in vitro. To test the effects of GPVI-Fc in vivo, arterial thrombosis was induced in the mouse carotid artery, and platelet-vessel wall interactions were visualized by intravital fluorescence microscopy. Infusion of GPVI-Fc but not of control Fc virtually abolished stable arrest and aggregation of platelets following vascular injury. Importantly, GPVI-Fc but not control Fc, was detected at areas of vascular injury. These findings further substantiate the critical role of the collagen receptor GPVI in the initiation of thrombus formation at sites of vascular injury and identify soluble GPVI as a promising antithrombotic strategy.

Animals↗

PubMed2003

CD4+CD25+ regulatory T cells cure murine colitis: the role of IL-10, TGF-beta, and CTLA4.

Regulatory T cells are critical in regulating the immune response, and therefore play an important role in the defense against infection and control of autoimmune diseases. However, a therapeutic role of regulatory T cells in an established disease has not been fully established. In this study, we provide direct evidence that CD4(+)CD25(+) regulatory T cells can cure an established, severe, and progressive colitis. SCID mice developed severe colitis when adoptively transferred with naive CD4(+)CD25(-) T cells and infected with the protozoan parasite Leishmania major. The disease development can be completely halted and symptoms reversed, with a healthy outcome, by transferring freshly isolated or activated CD4(+)CD25(+) T cells from syngeneic donors. The therapeutic effect of the regulatory T cells was completely blocked by treatment of the recipients with anti-IL-10R, anti-CTLA4, or anti-TGF-beta Ab. However, the resurgence of colitis under these treatments was not accompanied by the reactivation of Th1 or Th2 response nor was it correlated to the parasite load. These results therefore demonstrate that CD4(+)CD25(+) T cells are therapeutic and that the effect is mediated by both IL-10/TGF-beta-dependent and independent mechanisms. Furthermore, colitis can manifest independent of Th1 and Th2 responses.

Adoptive Transfer↗

PubMed2003

Resident murine alveolar and peritoneal macrophages differ in adhesion of apoptotic thymocytes.

Apoptotic cells must be cleared efficiently by macrophages (Mø) to prevent autoimmunity, yet their ingestion impairs Mø microbicidal function. The principal murine resident lung phagocyte, the alveolar Mø (AMø), is specifically deficient at apoptotic cell ingestion, both in vitro and in vivo, compared with resident peritoneal Mø (PMø). To further characterize this deficiency, we assayed static adhesion in vitro using apoptotic thymocytes and resident AMø and PMø from normal C57BL/6 mice. Adhesion of apoptotic thymocytes by both types of Mø was rapid, specific, and cold-sensitive. Antibody against the receptor tyrosine kinase MerTK (Tyro12) blocked phagocytosis but not adhesion in both types of Mø. Surfactant protein A increased adhesion and phagocytosis by AMø, but not to the levels seen using PMø. Adhesion was largely cation-independent for PMø and calcium-dependent for AMø. Adhesion was not inhibited in either Mø type by mAbs against beta1 or beta3 integrins or scavenger receptor I/II (CD204), but AMø adhesion was inhibited by specific mAbs against CD11c/CD18. Thus, resident murine tissue Mø from different tissues depend on qualitatively disparate receptor systems to bind apoptotic cells. The decreased capacity of murine AMø to ingest apoptotic cells is only partially explained by reduced initial adhesion.

Animals↗

PubMed2003

Syk activation is a leukotriene B4-regulated event involved in macrophage phagocytosis of IgG-coated targets but not apoptotic cells.

Macrophages are called upon to ingest both IgG-coated targets and apoptotic cells. Important roles for tyrosine kinase Syk and leukotriene B4 (LTB4) are recognized in FcgammaR-mediated phagocytosis. Here we evaluated the roles of Syk and LTB4 in macrophage phagocytosis of apoptotic thymocytes versus IgG-coated erythrocytes. Macrophage ingestion of apoptotic thymocytes was not influenced by exogenous or endogenous LTB4 nor associated with Syk activation (phosphorylation). By contrast, LTB4 dose-dependently amplified FcgammaR-mediated phagocytosis as well as Syk activation. Furthermore, a role for endogenous LTB4 in Syk activation during FcgammaR-mediated phagocytosis was demonstrated using pharmacologic and genetic abrogation of 5-lipoxygenase. LTB4 was unique among 5-lipoxygenase products in this regard, since LTD4 and 5-hydroxyeicosatetraenoic acid (HETE) were unable to amplify Syk activation in response to FcgammaR engagement. Ca2+ chelation studies revealed that FcgammaR-mediated Syk activation as well as LTB4 amplification thereof was Ca2+ regulated. These 2 parallel phagocytic processes therefore exhibit initial divergence in signal transduction events, with Syk activation being an LTB4-regulated event in FcgammaR-mediated but not apoptotic cell ingestion. As LTB4 is an important proinflammatory product of macrophages, we speculate that this divergence evolved to permit FcgammaR-mediated phagocytosis to proceed in an inflammatory milieu, while apoptotic cell clearance is noninflammatory.

Animals↗

PubMed2003

Immunogene therapy of tumors with vaccine based on xenogeneic epidermal growth factor receptor.

The breaking of immune tolerance against self epidermal growth factor receptor (EGFr) should be a useful approach for the treatment of receptor-positive tumors with active immunization. To test this concept, we constructed a plasmid DNA encoding extracellular domain of xenogeneic (human) EGFr (hEe-p) or corresponding control mouse EGFr (mEe-p) and empty vector (c-p). Mice immunized with hEe-p showed both protective and therapeutic antitumor activity against EGFr-positive tumor. Sera isolated from the hEe-p-immunized mice exhibited positive staining for EGFr-positive tumor cells in flow cytometric analysis and recognized a single 170-kDa band in Western blot analysis. Ig subclasses responded to rEGFr proteins were elevated in IgG1, Ig2a, and Ig2b. There was the deposition of IgG on the tumor cells. Adoptive transfer of the purified Igs showed the antitumor activity. The increased killing activity of CTL against EGFr-positive tumor cells could be blocked by anti-CD8 or anti-MHC class I mAb. In vivo depletion of CD4(+) T lymphocytes could completely abrogate the antitumor activity, whereas the depletion of CD8(+) cells showed partial abrogation. The adoptive transfer of CD4-depleted (CD8(+)) or CD8-depleted (CD4(+)) T lymphocytes isolated from mice immunized with hEe-p vaccine showed the antitumor activity. In addition, the increase in level of both IFN-gamma and IL-4 was found. Taken together, these findings may provide a new vaccine strategy for the treatment of EGFr-positive tumors through the induction of the autoimmune response against EGFr in a cross-reaction between the xenogeneic homologous and self EGFr.

Adoptive Transfer↗

PubMed2003

An efficient and practical N-methylation of amino acid derivatives.

[reaction: see text] An efficient and practical N-methylation of amino acid derivatives with dimethyl sulfate in the presence of sodium hydride and a catalytic amount of water is described. Reaction of water with sodium hydride generated highly reactive dry sodium hydroxide, which led to much faster reaction rates than powdered sodium hydroxide itself.

Amino Acids↗

PubMed2003

Is the target for thalamic deep brain stimulation the same as for thalamotomy?

Deep brain stimulation (DBS) has virtually replaced thalamotomy for the treatment of essential tremor. It is thought that the site for DBS is the same as the optimal lesion site; however, this match has not been investigated previously. We sought to determine whether the location of thalamic DBS matched the site at which thalamotomy would be performed. Eleven patients who had detailed microelectrode recording and stimulation for placement of DBS electrodes and subsequent successful tremor control were analysed. An experienced surgeon, blinded to outcome and final electrode position, selected the ideal thalamotomy site based on the reconstructed maps obtained intraoperatively. When the site of long-term clinically used DBS and theoretical thalamotomy location was calculated in three-dimensional space and compared for each of the x, y, and z axes in stereotactic space, there was no significant difference in the mediolateral location of DBS and theoretical lesion site. There was also no difference between the theoretical lesion site and the placement of the tip of the electrode; however, the active electrodes used for chronic stimulation were significantly more anterior (P = 0.005) and dorsal (P = 0.034) to the ideal thalamotomy target. This mismatch may reflect the compromise required between adverse and beneficial effects with chronic stimulation, but it also suggests different mechanisms of effect of DBS and thalamotomy.

Adult↗

PubMed2003

Functional incorporation of integrins into solid supported membranes on ultrathin films of cellulose: impact on adhesion.

Biomimetic models of cell surfaces were designed to study the physical basis of cell adhesion. Vesicles bearing reconstituted blood platelet integrin receptors alpha(IIb)beta(3) were spread on ultrathin films of cellulose, forming continuous supported membranes. One fraction of the integrin receptors, which were facing their extracellular domain toward the aqueous phase, were mobile, exhibiting a diffusion constant of 0.6 micro m(2) s(-1). The functionality of receptors on bare glass and on cellulose cushions was compared by measuring adhesion strength to giant vesicles. The vesicles contained lipid-coupled cyclic hexapeptides that are specifically recognized by integrin alpha(IIb)beta(3). To mimic the steric repulsion forces of the cell glycocalix, lipids with polyethylene glycol headgroups were incorporated into the vesicles. The free adhesion energy per unit area deltag(ad) was determined by micro-interferometric analysis of the vesicle's contour near the membrane surface in terms of the equilibrium of the elastic forces. By accounting for the reduction of the adhesion strength by the repellers and from measuring the density of receptors one could estimate the specific receptor ligand binding energy. We estimate the receptor-ligand binding energy to be 10 k(B)T under bioanalogue conditions.

Biomimetic Materials↗

PubMed2003

Structural and functional analysis of the middle segment of hsp90: implications for ATP hydrolysis and client protein and cochaperone interactions.

Activation of client proteins by the Hsp90 molecular chaperone is dependent on binding and hydrolysis of ATP, which drives a molecular clamp via transient dimerization of the N-terminal domains. The crystal structure of the middle segment of yeast Hsp90 reveals considerable evolutionary divergence from the equivalent regions of other GHKL protein family members such as MutL and GyrB, including an additional domain of new fold. Using the known structure of the N-terminal nucleotide binding domain, a model for the Hsp90 dimer has been constructed. From this structure, residues implicated in the ATPase-coupled conformational cycle and in interactions with client proteins and the activating cochaperone Aha1 have been identified, and their roles functionally characterized in vitro and in vivo.

Adenosine Triphosphatases↗

PubMed2003

Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases.

Muscle-specific deficiency of phosphorylase kinase (Phk) causes glycogen storage disease, clinically manifesting in exercise intolerance with early fatiguability, pain, cramps and occasionally myoglobinuria. In two patients and in a mouse mutant with muscle Phk deficiency, mutations were previously found in the muscle isoform of the Phk alpha subunit, encoded by the X-chromosomal PHKA1 gene (MIM # 311870). No mutations have been identified in the muscle isoform of the Phk gamma subunit (PHKG1). In the present study, we determined Q1the structure of the PHKG1 gene and characterized its relationship to several pseudogenes. In six patients with adult- or juvenile-onset muscle glycogenosis and low Phk activity, we then searched for mutations in eight candidate genes. The coding sequences of all six genes that contribute to Phk in muscle were analysed: PHKA1, PHKB, PHKG1, CALM1, CALM2 and CALM3. We also analysed the genes of the muscle isoform of glycogen phosphorylase (PYGM), of a muscle-specific regulatory subunit of the AMP-dependent protein kinase (PRKAG3), and the promoter regions of PHKA1, PHKB and PHKG1. Only in one male patient did we find a PHKA1 missense mutation (D299V) that explains the enzyme deficiency. Two patients were heterozygous for single amino-acid replacements in PHKB that are of unclear significance (Q657K and Y770C). No sequence abnormalities were found in the other three patients. If these results can be generalized, only a fraction of cases with muscle glycogenosis and a biochemical diagnosis of low Phk activity are caused by coding, splice-site or promoter mutations in PHKA1, PHKG1 or other Phk subunit genes. Most patients with this diagnosis probably are affected either by elusive mutations of Phk subunit genes or by defects in other, unidentified genes.

Adult↗

PubMed2003

Neural substrates of microstimulation-evoked tingling: a chronaxie study in human somatosensory thalamus.

Intra-operative micro-electrode stimulation of sensorimotor thalamus produces paraesthesia or tingling in various body regions and is used to map somatotopy prior to implantation of deep brain-stimulating electrodes in awake patients. The neural elements affected by such microstimulation are unknown. Using paraesthesia as the behavioural-physiological response threshold, we measured chronaxie times for microstimuli applied to both somatosensory thalamic nuclei (cellular region) and its axonal afferents, the medial lemniscus. White matter chronaxie times were relatively unimodal, whereas two different clusters of chronaxie times were identified in grey matter: one corresponding to that of the medial lemniscus and the other about five times longer and compatible with that obtained from cell somata. Therefore, excitations of local axons and/or cell bodies can both contribute to the paraesthesia evoked during intra-operative thalamic mapping.

Brain Mapping↗

PubMed2003

ICP-AES detection of ultratrace aluminum(III) and chromium(III) ions with a microcolumn preconcentration system using dynamically immobilized 8-hydroxyquinoline on TiO2 nanoparticles.

Titanium dioxide nanoparticle dynamically loaded with 8-hydroxyquinoline (nanometer TiO2-Oxine) was used as a solid-phase extractant for the preconcentration of trace amounts of aluminum(III) and chromium(III) prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimal conditions for preparing nanometer TiO2-Oxine were obtained. Also, the separation/preconcentration conditions of analytes, including the effects of the pH, the sample flow rate and the volume, the elution solution and the interfering ions on the recovery of the analytes were investigated. At pH 6.0, the adsorption capacity of nanometer TiO2-Oxine was found to be 5.23 mg g(-1) and 9.58 mg g(-1) for Al(III) and Cr(III), respectively. An enrichment factor of 50 was achieved by this method, and the detection limits (3sigma) for Al(III) and Cr(III) were 1.96 and 0.32 microg L(-1) respectively. The proposed method was applied for the determination of trace Al(III) and Cr(III) in biological samples and lake water with satisfactory results.

Journal Article↗

PubMed2003

Adsorption behavior of noble metal ions (Au, Ag, Pd) on nanometer-size titanium dioxide with ICP-AES.

The adsorption behavior of gold (Au), silver (Ag) and palladium (Pd) on nanometer-size titanium dioxide (NSTD) at low concentrations was studied using inductively coupled plasma atomic emission spectrometry (ICP-AES). A preconcentration procedure of the analytes was carried out using NSTD as a solid-phase extractant before their determination by ICP-AES. The optimum conditions for adsorption were studied in detail, and under the condition that Au, Ag and Pd ions could be adsorbed and recovered quantitatively. The static adsorption capacities of Au, Ag and Pd on NSTD were 22.63, 14.06 and 11.82 mg/g, respectively. For the elution of gold, silver and palladium, a mixture of 5% thiourea solution and 3 mol L(-1) HNO3 was used. The parameters tested included: pH conditions, contact time of the analytes with NSTD, flow rate, adsorption capacity and sorption kinetics. According to the definition of IUPAC, the detection limits (3sigma) of this method for Au, Ag and Pd with an enrichment factor of 50 were (0.016), (0.006) and (0.012) microg mL(-1), respectively, the relative standard deviations (RSD) were 8.7%, 4.5% and 7.4%, respectively (n = 6). Some geological samples were determined with satisfactory results.

Journal Article↗

PubMed2003

Effects of prednisone on bone mineral density and biomechanical characteristics of the femora and lumbar vertebras in rats.

OBJECTIVE: To explore effects of prednisone on the bone mineral density (BMD) and biomechanics of the femora and lumbar vertebras in rats. METHODS: Twenty one 3-month-old male Sprague-Dawley rats weighing 226+/-12 g were randomly divided into basal control, age-matched and hormone groups. The rats in basal control group were killed at the beginning of the experiment without any treatment, and those in age-matched group were given oral normal saline (5 ml x kg(-1) x d(-1)) while the rats in hormone group received oral prednisone acetate (4.5 ml x kg(-1) x d(-1) twice a week) to establish osteoporotic models. The treatment for the latter 2 groups of rats lasted for 90 days, after which the BMD and mechanical measurements of the femurs and L5 vertebra were carried out by way of torsion, three-point bending and compression tests. The measurements were also conducted in the basal control group at the time indicated above. RESULTS: In hormone group, the total BMD of the femora and L5 vertebra was decreased by 14.64%(P<0.01), and the BMD in the right and left distal femoral segments and the vertebra decreased by 21.42% (P<0.01), 19.62% (P<0.05) and 23.48%(P<0.01), respectively, in comparison with the control group. In the meantime, the loads of three-point bending test in hormone group was decreased by 17.1%(P<0.05), whereas the rest parameters tended to decrease as compared with the control group. CONCLUSIONS: Chronic use of corticosteroid is more liable to cause bone mass loss in rat cancellous bone than in the cortical bone, and mechanical properties of the cortical and cancellous bone, especially those of the latter, will also decline, to give rise to easy bone fracture at the trabecular bone in osteoporotic conditions.

Animals↗

PubMed2003

Effects of low doses of hydrochloride tetracycline on bone metabolism and uterus in ovariectomized rats.

AIM: To study the effects of low doses of hydrochloride tetracycline (Tc) on bone metabolism and uterus in the ovariectomized (Ova) rats. METHODS: Forty 3-month-old rats were randomly divided into 5 groups: sham group, Ova group, Tc1 group (1.2 mg/kg/d), Tc2 group (4.8 mg/kg/d), and estrone group (1.48 mg/kg/d), oral fed for 3 months. The proximal tibia metaphyses were processed undecalcified for quantitative bone histomorphometry and the soft tissues were processed in paraffin for pathological observation. RESULTS: Placebo-treated (lactose) Ova rats were characterized by trabecular area (TA) decreasing and their architecture worsening compared with sham controls, and bone resorption was over formation with high bone turnover. The uteri were atrophy. (2) In estrone-treated group, TA and trabecular numbers were significantly increased and the trabecular separation decreased vs Ova group. Estrone slowed down Ova-inducing bone high turnover. But the size, weight, and the endometrium of the uteri in this group were increased vs Ova group. (3) TA was increased in both Tc1 and Tc2 groups compared with Ova rats. Tc maintained bone formation indices almost at Ova level, and only decreased mineral apposition rate (MAR) in Tc1 group, and declined bone resorption perimeter. The uteri and the cell of liver and kidney almost maintained at Ova level; Tc2 decreased labeling perimeter and increased MAR in comparison with Tc1 group. The uteri were atrophy, whose size maintained at Ova level; yellow labeling was not found in bone with these doses of Tc, while yellow labeling could be seen with the doses of 30 mg/kg/d of Tc for bone marker. CONCLUSION: The two doses of Tc have similar effects on preventing bone loss in Ova rats while the bone formation and uterus are not affected. However, Tc2 does not have more effects on increasing bone mass, Tc2 causes less mild damages to the liver and kidneys.

Animals↗

PubMed2003

[Piperazinyl estrone prevents bone loss in ovariectomized rats].

AIM: To determine the effect of piperazinyl estrone, a new estrogen derivative, on bone turnover, bone mass and uteri in ovariectomized rats. METHODS: Female Sprague-Dawley rats were ovariectomized (OVX) or sham operated (sham) at the age of 3 months and treated with estrone (E) at 0.75 mg.kg-1.d-1, or with piperazinyl estrone (P-E) at 1 or 10 mg.kg-1.d-1, orally, for 3 months. At the time of death, the uterine weight was measured. Bone histomorphometric analysis of proximal tibial metaphyses (PTM) was performed in undecalcified sections. RESULTS: Bone histomorphometric data showed that the percent trabecular area (% Tb.Ar) of OVX rats with bone high turnover was significantly decreased. The uteri were atrophied. The percent trabecular area (% Tb.Ar) of estrone treated group was increased in decreasing bone turnover manner. But the size and weight of uteri in this group were increased vs OVX group. The bone loss induced by OVX was preserved by P-E treatment, but the mechanism of maintaining bone is different from that of E-treated rats. P-E treatment in low dose did not decrease any bone formation indices, such as percent labeling perimeter, bone formation rate per bone volume (BFR/BV), except bone mineral apposition rate (MAR) compared with E-treated group, and maintained them at OVX level. The uteri were found to be in atrophy compared with the match dose (0.75 mg) of E-treated OVX rats. But rats treated with high dose of P-E showed the same change like E-treated group. CONCLUSION: The finding of this study shows that lower dosage of piperazinyl estrone has effect on preventing the bone losses in OVX rats, while the bone formation and the uterus are not affected, thus supporting the hypothesis that piperazinyl estrone has the potential to prevent postmenopausal bone loss in women with less side effects.

Animals↗

PubMed2003

[Electrochemical corrosion characteristics of Ni-Cr alloy in artificial saliva].

OBJECTIVE: The aim of this study is to determine the electrochemical corrosion characteristics of Ni-Cr alloys in vitro. METHODS: The electrochemical corrosion behavior of Ni-Cr alloys was studied by polarization curves in artificial saliva at 36.5 degrees C (pH = 7.0) to measure the corrosion potential and self-corrosion current density. With X-ray photoelectron spectroscopy, the element content was analyzed. RESULTS: It was found that the dot corrosion voltage of Ni-Cr was -390 mv, and passivation voltage -160 mv. The area of active dissolvation was from -160 mv to -270 mv. The self-corrosion current density is 0.262 micro Acm(-2). From XPS, the content of Ni, Cr, Mo, Fe was increasing gradually, and the content of O, C was decreasing gradually. The content of Ca decreased because Ca existed in the artificial saliva. CONCLUSION: After polarization curve test, Ni-Cr alloy would occur corrosive reaction, and the corrosion product would attach to the surface of the material.

Chromium Alloys↗