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Biomedical subjects

Tao He

Publications and source records attributed to Tao He.

At least 55 records · Page 3Linked to original sources
PubMed2004

Comparison between the effects of TiO2 synthesized by photoassisted and conventional sol-gel methods on the photochromism of WO3 colloids.

WO3 colloids can exhibit a blue color under UV-light irradiation due to the absorption of electrons trapped at the energy levels within the forbidden gap and this coloration performance can be improved by TiO2 nanoparticles. In this work, it is found that TiO2 prepared by the photoassisted method (TiO2-P) exhibits stronger enhancement effects than that prepared by the conventional sol-gel method (TiO2-C). Several possible mechanisms have been proposed to account for this phenomenon. The migration of charge carriers toward different directions is promoted since the flat-band potential of TiO2-P colloids is more negative than that of TiO2-C and the contact between WO3 and TiO2 particles is improved in the WO3/TiO2-P system; there are more efficient TiO2 and hole scavengers (i.e., Ti3+ and/or TiO2-O2*- species) in the system containing TiO2-P; the bandgap of TiO2-P becomes narrowed, and so on. In addition, the potential applications of this process are also discussed briefly.

Absorption↗
PubMed2004

Charge ordering, commensurability, and metallicity in the phase diagram of the layered NaxCoO2.

The phase diagram of nonhydrated NaxCoO2 has been determined by changing the Na content x using a series of chemical reactions. As x increases from 0.3, the ground state goes from a paramagnetic metal to a charge-ordered insulator (at x=1/2), then to a "Curie-Weiss metal" (around 0.70), and finally to a weak-moment magnetically ordered state (x>0.75). The unusual properties of the state at 1/2 (including particle-hole symmetry at low T and enhanced thermal conductivity) are described. The strong coupling between the Na ions and the holes is emphasized.

Journal Article↗
PubMed2004

Specific in vivo phosphorylation sites determine the assembly dynamics of vimentin intermediate filaments.

Intermediate filaments (IFs) continuously exchange between a small, depolymerized fraction of IF protein and fully polymerized IFs. To elucidate the possible role of phosphorylation in regulating this equilibrium, we disrupted the exchange of phosphate groups by specific inhibition of dephosphorylation and by specific phosphorylation and site-directed mutagenesis of two of the major in vivo phosphorylation sites determined in this study. Inhibition of type-1 (PP1) and type-2A (PP2A) protein phosphatases in BHK-21 fibroblasts with calyculin-A, induced rapid vimentin phosphorylation in concert with disassembly of the IF polymers into soluble tetrameric vimentin oligomers. This oligomeric composition corresponded to the oligopeptides released by cAMP-dependent kinase (PKA) following in vitro phosphorylation. Characterization of the (32)P-labeled vimentin phosphopeptides, demonstrated Ser-4, Ser-6, Ser-7, Ser-8, Ser-9, Ser-38, Ser-41, Ser-71, Ser-72, Ser-418, Ser-429, Thr-456, and Ser-457 as significant in vivo phosphorylation sites. A number of the interphase-specific high turnover sites were shown to be in vitro phosphorylation sites for PKA and protein kinase C (PKC). The effect of presence or absence of phosphate groups on individual subunits was followed in vivo by microinjecting PKA-phosphorylated (primarily S38 and S72) and mutant vimentin (S38:A, S72:A), respectively. The PKA-phosphorylated vimentin showed a clearly decelerated filament formation in vivo, whereas obstruction of phosphorylation at these sites by site-directed mutagenesis had no significant effect on the incorporation rates of subunits into assembled polymers. Taken together, our results suggest that elevated phosphorylation regulates IF assembly in vivo by changing the equilibrium constant of subunit exchange towards a higher off-rate.

Amino Acid Sequence↗
PubMed2004

Quantitation of phosphopeptides using affinity chromatography and stable isotope labeling.

Reversible phosphorylation of proteins represents an important component of cellular signaling pathways. The isolation of phosphoproteins in complex mixtures and the determination of the level of phosphorylation have been and remain a major challenge. It has prompted the development of several strategies, including immobilized metal affinity capture to enrich for phosphorylated peptides. An improved methodology was published (Ficarro, et al., Nature Biotechnology 2002, 20, 301-305) that showed increased selectivity through esterification of amino acid side chain carboxylic groups of enzymatically digested peptides. This method was applied for relative quantitation of phosphopeptides in conjunction with the use of stable isotope labeling. The merits and limits of the approach are discussed and its application to the analysis of the effects of serum starvation on in vitro cultured human lung cells is presented.

Amino Acid Sequence↗
PubMed2004

Semantic short-term memory and its role in sentence processing: a replication.

Previous studies have shown that an aphasic patient (AB) with a semantic short-term memory deficit (STM) had difficulties comprehending and producing sentences with structures that demanded the simultaneous retention of several individual word meanings (Martin & Freedman, 2001a, 2001b; Martin & Romani, 1994; Martin, Shelton, & Yaffee, 1994). The present study provides a replication of these findings with an additional case (ML) who shows a striking dissociation between preserved semantic knowledge and disrupted semantic STM. ML performed poorly on comprehension tasks for sentences that required the retention of single word meanings across several intervening words. In contrast, he did not show an effect of intervening words on processing grammatical relations. ML had difficulty producing adjective-noun phrases, though able to produce the individual nouns and adjectives. These findings support the contention that there is a semantic retention capacity, involved in both comprehension and production, that is separate from semantic knowledge representations.

Aged↗
PubMed2004

Endothelium regeneration on luminal surface of polyurethane vascular scaffold modified with diamine and covalently grafted with gelatin.

Using the recently developed surface modification technique, free amino groups have been introduced onto polyester-type polyurethane (PU) scaffolds. The introduction of these free amino groups increases the surface energy and provides a convenient way to further immobilize bioactive species such as gelatin, collagen or chitosan, etc. on the scaffold surface by employing glutaraldehyde as a coupling agent. These modifications are advantageous to enhance cell-material interaction. The culture of human umbilical vein endothelial cells (HUVECs) in vitro proved that the cell proliferation ratio of both the aminolyzed and the biomacromolecules-immobilized PU membranes was improved greatly comparing with the control PU. Scanning electron microscopy and confocal laser scanning microscopy observations displayed that the gelatin-immobilized PU vascular scaffold had formed a monolayer of endothelial intima on its luminal surface after HUVECs were cultured for 6 d. Therefore, the aminolysis and the following biomacromolecule immobilization is a promising way to enhance the cell-PU interaction that can accelerate the endothelium regeneration, which is crucial for blood vessel tissue engineering.

Biocompatible Materials↗
PubMed2004

The role of colonic microbiota in lactose intolerance.

In a previous study we observed a clear difference in lactose intolerance symptoms after a 25-g lactose load in two groups of persons with lactase nonpersistence and similar small intestinal lactase activity. From this observation we hypothesized a colon resistance factor. To identify this factor, the microbial composition of fecal samples of the two lactose intolerant groups (one with mild symptoms, n = 16, and one with diarrhea-predominant symptoms, n = 11) was compared using the fluorescent in situ hybridization technique. Large interindividual differences were found in the numbers of total bacteria and main groups of bacteria (CV: 0.65 and 0.64-0.82 respectively). The bacterial numbers were not significantly different between the two groups. A significant negative correlation, however, was found between the individual symptom scores of the intolerant persons and the numbers of total hybridizable bacteria (r(s) = -0.42, P = 0.03). The results suggest that an increased number of bacteria might contribute--by means of a higher fermentative capacity--to the reduction of lactose intolerance symptoms.

Adult↗
PubMed2004

The comparative efficacy of stabilized stannous fluoride/sodium hexametaphosphate dentifrice and sodium fluoride/triclosan/copolymer dentifrice for the control of gingivitis: a 6-month randomized clinical study.

BACKGROUND: Antimicrobial agents such as stannous fluoride and triclosan have been incorporated into dentifrice formulations and have been shown to be effective in reducing gingivitis. The objective of this study was to compare the anti-gingivitis efficacy of a 0.454% stannous fluoride/sodium hexametaphosphate dentifrice to a positive control triclosan/copolymer dentifrice. METHODS: This was a 6-month, randomized, double-masked, parallel-group study conducted according to the American Dental Association guidelines for evaluating chemotherapeutic products for the control of gingivitis. A 0.454% stannous fluoride/sodium hexametaphosphate dentifrice was tested against a commercially available positive control dentifrice (0.30% triclosan/2.0% Gantrez copolymer). Following baseline measurements, subjects received a dental prophylaxis. Subjects were then instructed to brush twice daily for 60 seconds using their assigned product. Tooth brushing was supervised for 3 days of each week. Clinical examinations using a gingival index were performed at baseline and at 3 and 6 months. RESULTS: A total of 199 subjects were enrolled and 186 completed the 6-month study. Average baseline gingivitis and bleeding scores were similar for the two treatment groups. After 6 months, the experimental group had statistically significantly less gingivitis (25.8%) and statistically significantly less bleeding (27.4%) on average compared to the control group. Neither adverse oral soft tissue effects nor tooth staining were reported. CONCLUSION: Within the limits of the study protocol, the results demonstrated superior therapeutic benefits for the stabilized 0.454% stannous fluoride/sodium hexametaphosphate dentifrice in reducing gingivitis compared to the triclosan/copolymer control in this partially supervised study.

Adolescent↗
PubMed2004

Effects of TCMP-1 on the changes of platelet endothelial cell adhesion molecule-1 expression in acute edematous pancreatitis.

BACKGROUND: Traditional Chinese medicine is a potent agent in the management of clinical and experimental acute pancreatitis (AP), but the molecular mechanism of its therapeutic action is unclear. Numerous experimental and clinical studies have shown that platelet endothelial cell adhesion molecule-1 (PECAM-1) is pivotal to leukocyte recruitment, which results in microcirculatory injury during inflammation, but its role in acute pancreatitis is poorly understood. We investigated the effects of a compound of traditional Chinese medicine pancreatitis-1 (TCMP-1) on the changes of platelet endothelial cell adhesion molecule-1 (PECAM-1) expression on polymorphonuclear leukocytes (PMNs) in acute edematous pancreatitis (AEP). METHODS: The model of acute pancreatitis was established by subcutaneous injection of caerulein, and TCMP-1 treated groups were given TCMP-1 by catheterization from mouth to stomach (20 ml/kg) immediately after first time subcutaneous injection of caerulein. The changes of expression of PECAM-1 on leukocytes from the blood of the splenic vein and inferior vena cava were determined by flow cytometry. RESULTS: In the AEP group, expression of PECAM-1 on PMNs was not significantly different between pancreatic microcirculation and systemic circulation at AEP2h and AEP4h time point. Then from AEP4h time point to AEP8h time point, expression of PECAM-1 was up-regulated in systemic circulation while it was down-regulated in pancreatic microcirculation and was significantly different between pancreatic microcirculation and systemic circulation at AEP8h time point (P<0.05). In the TCMP-1 treated group, compared with the AEP group, expression of PECAM-1 on PMNs decreased in different levels between pancreatic microcirculation and systemic circulation and was of significant difference at AEP8h time point (P<0.05). CONCLUSION: Inhibition of PECAM-1 expression on PMNs may prevent PMNs from transmigration through the endothelium and may be one of the treatment mechanisms of TCMP-1 decoction on AEP.

Acute Disease↗
PubMed2004

[A new approach to protein phosphorylation modification analysis for neuron].

OBJECTIVE: To develop a new method for analysis of protein phosphorylation modification in cultured neuron. METHODS: Cultured neurons were pre-incubated in DMEM without sodium phosphate for 15 min to deplete the metabolic pools. Neurons were then labeled with [32P] orthophosphate (2.78 x 10(6) Bq/ml) for 1.5 h and stimulated by either insulin (100 nmol/L), EGF (20 nm/L) or saline for 0, 5, 20, 60, 120 min. Reactions were terminated by freezing neurons in liquid nitrogen prior to the solubilizing of them in a lysis buffer containing 8 mol/L urea, 4% CHAPS, 2% Bio-lyte, pH 3-10, 2 mmol/L TBP. Protein concentrations were determined with Bio-Rad DC Protein Assay kit. The 32P-labled lysates isoelectrically focused on IPG Drystrip pH 3-10 or pH 4-7 Linear gels were subsequently separated in second-dimensional SDS-PAGE. The dried gel was autoradiographed for 5 days at -70 degrees C with an intensifying screen. Alternatively, the separated proteins were visualized by Coomassie Brilliant Blue (CBB) R250 straining. RESULTS: Autoradiography of the 2-DE-separated 32P-laebled neuron lysates revealed around 100 phosphoproteins. This phosphoprotein pattern was stable at 1.5 h after radiolabelling and did not vary significantly for up to 4 h further incubation in the absence of hormone. Most of the major proteins which are phosphorylated in response to insulin or EGF migrated with pH 4.6-6.5 and MW 20000-130000. Insulin and EGF induced similar but not identical patterns of protein phosphoryltion in neurons. Only a few phosphoproteins were abundant enough to be visualized by CBB straining, suggesting that abundance of these phosphoproteins is extremely low. Responses to both isulin and EGF are marked by more increased labeling of the constitutive phosphoproteins, compared with the appearance of new phosphoproteins. CONCLUSION: This approach co-application of 32P-labeled with 2-DE separation and autoradiography has proven to be specific and sensitive in phosphoprotein analysis for neuron. It was valuable in functional proteomic analysis for protein phosphorylation modification during cellular signal transduction.

Animals↗
PubMed2004

Pharmacodynamic and pharmacokinetic effects in gingival crevicular fluid from re-dosing during brushing.

The IntelliClean System from Sonicare and Crest combines a rechargeable sonic power toothbrush and a novel liquid toothpaste into one integrated system, providing the opportunity to re-dose with toothpaste during the brushing cycle. The purpose of this study was to investigate cleaning effects from in-mouth re-dosing with toothpaste during the brushing cycle vs conventional bolus dosing. This was a randomized, examiner-blind, six-period, crossover clinical study. Eighteen adult subjects used an experimental integrated system employing either a re-dosing regimen (2 doses at the start of brushing with 1 additional in-mouth dose during the last 30 seconds of brushing [2+1]) or a conventional regimen (2 doses at the start of brushing only [2+0]). Gingival crevicular fluid (GCF) was sampled at the final brushing quadrant from a preselected site in the gingival sulcus using filter strips at baseline and at 4, 15, and 120 minutes postbrushing. Mean change from baseline in the concentrations of total facultative anaerobes (TFAs) and gram-negative anaerobes (GNAs) in the GCF at 120 minutes posttreatment were modeled separately using general linear mixed models. Area under the curve of surfactant (sodium dodecyl sulfate [SDS]) in GCF over 2 hours postbrushing was calculated and modeled using an analysis of variance model. All hypotheses were tested 2-sided at the 5% significance level. Relative to the conventional regimen, the re-dosing (2+1) regimen produced a significantly greater reduction in log10 (TFA colony-forming units [CFU]/microL GCF) after brushing, 0.99+/-0.12 vs 0.65+/-0.12 (mean change +/- standard error), and a significantly greater reduction in log10 (GNA CFU/microL GCF) after brushing, 0.75 +/-0.14 vs 0.45 +/- 0.14. The re-dosing regimen led to significantly more SDS in GCF relative to the conventional regimen over the 2-hour time period. Re-dosing of liquid toothpaste during the brushing cycle with the IntelliClean System leads to a significantly increased cleaning effect, as defined by a reduced bacterial count in GCF, and significantly higher levels of surfactant in the GCF up to 2 hours after the brushing event.

Adult↗
PubMed2004

An experimental gingivitis study to evaluate the clinical effects of a stannous fluoride dentifrice.

PURPOSE: A double blind, controlled, parallel group trial utilizing the experimental gingivitis model was performed on thirty young adults to evaluate the clinical effects of a 0.45% stannous fluoride dentifrice used as a slurry on dental biofilm formation and the development of gingivitis. MATERIAL AND METHODS: Following a thorough examination and oral prophylaxis procedures, subjects were randomly assigned to apply one of the following dentifrices twice daily over a three-week period: A) dentifrice slurry without active ingredients; B) 0.45% stannous fluoride gel; and C) Colgate Total dentifrice slurry (0.30% triclosan, 0.24% sodium fluoride, 2% copolymer). RESULTS: After three weeks, the stannous fluoride dentifrice significantly (p < 0.05) reduced gingivitis compared with the Colgate Total group by 39.7%. Gingival bleeding was also reduced relative to the Colgate Total group. This difference was statistically significant (P < 0.05). During the experimental period, the mean PII scores increased almost linearly in all three groups without yielding any statistically significant differences. CONCLUSIONS: The results of this clinical trial demonstrated that, over a three-week period, the application of a 0.45% SnF2 gel significantly inhibited the onset of gingivitis compared to Triclosan/sodium fluoride/copolymer (Colgate Total). However, neither stannous fluoride nor Triclosan/sodium fluoride/ copolymer (Colgate Total) possessed sufficient antimicrobial activity to suppress biofilm formation in the absence of regular oral hygiene practices.

Adult↗
PubMed2003

[Study on the insulin and insulin receptor in the progression of renal ischemic and reperfusion].

OBJECTIVE: To evaluate the effect of insulin and it's receptor on the kidney of rabbit with acute ischemic/reperfusion injury. METHODS: Twenty three Japanese white rabbits were allocated randomly into the control group, ischemic/reperfusion group(IR group), and insulin treatment group(Ins-IR group). The IR group received clamping for 1 h followed by 2 h or 48 h of reperfusion. In the Ins-IR group, insulin injection (Ins 3U/kg, glucose 1.5 g/kg, K+ 4 mg/kg, Mg2+ 1.7 mg/kg) was administered intravenously twice a day for two days, whereas only normal saline in equal amount was given to the IR group and control group. At 2 h or 48 h after reperfusion, glucose and insulin in serum were determined. Rough plasma of renal tissue was prepared by repeated centrifugation. Insulin receptor in renal tissue was analyzed by radiologand binding assay. The binding data were calculated according to Scatchard using the ligand program. Statistical significance was analyzed with the paired t-test. RESULTS: The level of blood glucose increased after 2 h reperfusion in three groups, but the level in IR group increased much higher than those in control and Ins-IR groups(P < 0.05). The level of serum insulin of IR group after 2 h reperfusion was significantly higher than that of control (P < 0.05). Scatchard analysis showed curvilinear profiles, indicating that there are two classes of receptors with different affinity or the presence of a single class of receptors with a negative cooperative hormone-receptor interaction. Data analyzed by a two-site model showed that the values of Bmax1 (high affinity site), Bmax2 (low affinity site) and Kd1, Kd2 after 2 h reperfusion were significantly lower than those of control (P < 0.05). In IR-Ins group, only Bmax2 decreased (P < 0.05, compared with control). 48 h after IR there was no difference in Bmax1, Kd1 between the 3 groups, but Bmax2 of IR-Ins group was still lower than that of control (P < 0.001) and IR group (P < 0.05). The Kd2 of IR group increased (P < 0.05 compared with control and IR-Ins group). CONCLUSION: The results indicate that the effect of intrinsic insulin decreases during renal ischemic/reperfusion. The extrinsic insulin can protect renal tissue through its high affinity receptor. There exits down-regulation of low affinity receptor but none of high affinity receptor during insulin treatment.

Animals↗
PubMed2002

The intermediate filament protein keratin 8 is a novel cytoplasmic substrate for c-Jun N-terminal kinase.

Keratins 8 (K8) and 18 are the primary intermediate filaments of simple epithelia. Phosphorylation of keratins at specific sites affects their organization, assembly dynamics, and their interaction with signaling molecules. A number of keratin in vitro and in vivo phosphorylation sites have been identified. One example is K8 Ser-73, which has been implicated as an important phosphorylation site during mitosis, cell stress, and apoptosis. We show that K8 is strongly phosphorylated on Ser-73 upon stimulation of the pro-apoptotic cytokine receptor Fas/CD95/Apo-1 in HT-29 cells. Kinase assays showed that c-Jun N-terminal kinase (JNK) was also activated with activation kinetics corresponding to that of K8 phosphorylation. Furthermore, K8 was also phosphorylated on Ser-73 by JNK in vitro, yielding similar phosphopeptide maps as the in vivo phosphorylated material. In addition, co-immunoprecipitation studies revealed that part of JNK is associated with K8 in vivo, correlating with decreased ability of JNK to phosphorylate the endogenous c-Jun. Taken together, K8 is a new cytoplasmic target for JNK in Fas receptor-mediated signaling. The functional significance of this phosphorylation could relate to regulation of JNK signaling and/or regulation of keratin dynamics.

Amino Acid Sequence↗
PubMed2002

The physiology of colonic metabolism. Possibilities for interventions with pre- and probiotics.

The awareness is increasing that in the colon many metabolic processes take place in relation to the fermentation of our food, which might be relevant for health and disease. However, the relation between food, colon metabolism and health or disease is far from clear. In this overview, the physiology of colonic metabolism and possibilities for its modification by the use of pre- and probiotics are discussed. Results of in vitro and animal studies indicate a beneficial impact of probiotics on adverse metabolic processes in the colon, but confirmation in human studies has to be extended. The administration of prebiotics seems to be promising with regard to their capacity to modulate the bacterial composition in the colon and there are indications that prebiotics can beneficially influence colonic metabolism. Whether these modulations brought about by pre- or probiotics have an effect on the health of the host, however, needs to be established in most cases.

Animals↗
PubMed2002

Extensive set of 16S rRNA-based probes for detection of bacteria in human feces.

For the detection of six groups of anaerobic bacteria in human feces, we designed seven new 16S rRNA-based oligonucleotide probes. This set of probes extends the current set of probes and gives more data on the composition of the human gut flora. Probes were designed for Phascolarctobacterium and relatives (Phasco741), Veillonella (Veil223), Eubacterium hallii and relatives (Ehal1469), Lachnospira and relatives (Lach571), and Eubacterium cylindroides and relatives (Ecyl387), and two probes were designed for Ruminococcus and relatives (Rbro730 and Rfla729). The hybridization conditions for the new probes were optimized for fluorescent in situ hybridization, and the probes were validated against a set of reference organisms. The probes were applied to fecal samples of 11 volunteers to enumerate their target bacterial groups. The Phasco741 and Veil223 probes both detected average numbers below 1% of the total number of bacteria as determined with the bacterial kingdom-specific Bact338 probe. The Ecyl387 probe detected about 1.4%, the Lach571 and Ehal1469 probes detected 3.8 and 3.6%, respectively, and a combination of the Rbro730 and Rfla729 probes detected 10.3%. A set of 15 probes consisting of probes previously described and those presented here were evaluated in hybridization with the fecal samples of the same volunteers. Together, the group-specific probes detected 90% of the total bacterial cells.

Bacteria↗
PubMed2002

Prolongation of functional life-span of neutrophils by recombinant verotoxin 2.

OBJECTIVE: Verotoxin-producing Escherichia coli (VTEC) strains of serotype O157 : H7 have been implicated in a wide spectrum of diseases, including blood diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS). To further explore the pathological role of verotoxin (VT) in HUS and other VTEC associated diseases, we investigated the effects of recombinant verotoxin 2 (rVT2) on the biological activity of neutrophils. METHODS: The technique of flow cytometry, a fluorescent probe 2,7-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF/AM), and the assay of reduced cytochrome c to detect superoxide production were used in this study. RESULTS: gammaVT2 significantly inhibited spontaneous apoptosis in neutrophils. Neutrophils with prolonged survival due to gammaVT2 maintained various biological functions, such as the expression of adhesion molecules (shading CD62L and raising CD11b/CD18), adherence to human umbilical vein endothelial cells (HUVECs), and generation of superoxide (O(2)(-)). CONCLUSION: Prolongation of the functional life-span of neutrophils by gammaVT2 may accelerate inflammatory responses at sites of inflammation. This may play a crucial role in neutrophil-mediated tissue injury in HUS and other VTEC-associated diseases.

Apoptosis↗