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Biomedical subjects

Tao He

Publications and source records attributed to Tao He.

At least 19 recordsLinked to original sources

Layer-by-layer assembly of biomacromolecules on poly(ethylene terephthalate) films and fiber fabrics to promote endothelial cell growth.

Poly(ethylene terephthalate) (PET) film and PET vascular graft were modified by layer-by-layer (LBL) assembly of collagen and chondroitin sulfate (CS) to mimic the natural composition and structure of extracellular matrix. PET materials were first hydrolyzed to endow the surfaces with negative charge. Alternative assembly of positively charged collagen and negatively charged CS was then conducted in an LBL manner to produce biological multilayers. X-ray photoelectron spectroscopy confirmed the occurrence of hydrolysis and existence of collagen and CS. The stepwise layer growth on the PET film was monitored by UV-vis spectroscopy. The multilayers had sufficient stability to pass through the cell culture period (8 days). In vitro endothelial cell culture revealed that the incorporated biomacromolecules could significantly improve the cell attachment, proliferation, and viability. Cells showed more spreading morphology with preserved phenotype, as illustrated by scanning electron microscopy and factor VIII-related antigen immunocytochemistry, respectively.

Blood Vessels↗

Tuning the electronic structures of semiconducting SiC nanotubes by N and NHx (x=1,2) groups.

We investigate the stable configurations and electronic structures of silicon carbide nanotubes (SiCNTs) decorated by N and NHx (x=1,2) groups by using first-principles calculations. We find that these groups can be chemically incorporated into the network of SiCNTs in different ways, accompanied with the formation of N-C and N-Si bonds. The adsorbing energy of N and NHx (x=1,2) groups on (5,5) and (8,0) SiCNTs ranges from -1.82 to -7.19 eV. The electronic structures of SiCNTs can be effectively modified by these groups and display diverse characters ranging from semiconducting to semimetallic, depending on the chirality of SiCNTs as well as the way of the incorporation of these functional groups. The relationship between the electronic structures and the configurations of these functionalized SiCNTs is also addressed by performing projected density of states combined with Milliken population analysis. These results are expected to open a way to tune the electronic structures of SiCNTs which may have promising applications in building nanodevices.

Journal Article↗

Controlled modulation of conductance in silicon devices by molecular monolayers.

We have controllably modulated the drain current (I(D)) and threshold voltage (V(T)) in pseudo metal-oxide-semiconductor field-effect transistors (MOSFETs) by grafting a monolayer of molecules atop oxide-free H-passivated silicon surfaces. An electronically controlled series of molecules, from strong pi-electron donors to strong pi-electron acceptors, was covalently attached onto the channel region of the transistors. The device conductance was thus systematically tuned in accordance with the electron-donating ability of the grafted molecules, which is attributed to the charge transfer between the device channel and the molecules. This surface grafting protocol might serve as a useful method for controlling electronic characteristics in small silicon devices at future technology nodes.

Journal Article↗

dbRES: a web-oriented database for annotated RNA editing sites.

Although a large amount of experimentally derived information about RNA editing sites currently exists, this information has remained scattered in a variety of sources and in diverse data formats. Availability of standard collections for high-quality experimental data will be by of great help for systematic studying of RNA editing, especially for developing computational algorithm to predict RNA editing site. dbRES (http://bioinfo.au.tsinghua.edu.cn/dbRES) is a public database of known RNA editing sites. All sites are manually curated from literature and GenBank annotations. dbRES version 1.1 contains 5437 RNA editing sites of 251 transcripts, covering 96 organisms across plant, metazoan, protozoa, fungi and virus. dbRES provides comprehensive annotations and data summaries, including (but not limited to) transcript sequences, RNA editing types, editing site locations, amino acid changes, organisms, subcellular organelles (if available), cited references, etc. A user-friendly web interface is developed to facilitate both retrieving data and online display of RNA edit site information.

Databases, Nucleic Acid↗

A nestin scaffold links Cdk5/p35 signaling to oxidant-induced cell death.

The intermediate filament protein, nestin, has been implicated as an organizer of survival-determining signaling molecules. When nestin expression was related to the sensitivity of neural progenitor cells to oxidant-induced apoptosis, nestin displayed a distinct cytoprotective effect. Oxidative stress in neuronal precursor cells led to downregulation of nestin with subsequent activation of cyclin-dependent kinase 5 (Cdk5), a crucial kinase in the nervous system. Nestin downregulation was a prerequisite for the Cdk5-dependent apoptosis, as overexpression of nestin efficiently inhibited induction of apoptosis, whereas depletion of nestin by RNA interference had a sensitizing effect. When the underlying link between nestin and Cdk5 was analyzed, we observed that nestin serves as a scaffold for Cdk5, with binding restricted to a specific region following the alpha-helical domain of nestin, and that the presence and organization of nestin regulated the sequestration and activity of Cdk5, as well as the ubiquitylation and turnover of its regulator, p35. Our data imply that nestin is a survival determinant whose action is based upon a novel mode of Cdk5 regulation, affecting the targeting, activity, and turnover of the Cdk5/p35 signaling complex.

Apoptosis↗

Primary transcripts and expressions of mammal intergenic microRNAs detected by mapping ESTs to their flanking sequences.

MicroRNAs (miRNAs) are a class of approximately 22-nt small RNAs that regulate posttranscriptional gene expression. Thousands of expressed sequence tags (ESTs) have been identified by using upstream 2500-nt and downstream 4000-nt flanking sequences to BLAST in the dbEST database. The cotranscription of the miRNAs and their flanking sequences covered by the matched ESTs is verified by RT-PCR. It directly reveals that a large portion of mammalian intergenic miRNAs are first transcribed as long primary transcripts (pri-miRNAs). Also, the transcripts' ranges of tens of pri-miRNAs are predicted by the EST-extension method. We then extracted the tissue-specific expression information from the annotations of the matched ESTs and established the expression profile of the studied miRNAs for tens of tissues. This provided a new way to establish the expression profiles of miRNAs. Results show that the human brain, lung, liver, and eye and the mouse brain, eye, and mammary gland are tissues in which enriched numbers of miRNAs are expressed.

3' Flanking Region↗

The effect of toothbrushing regimens on the plaque inhibitory properties of an experimental cetylpyridinium chloride mouthrinse.

OBJECTIVE: The objective of this study was to determine the effect of various toothbrushing regimens with a standard fluoride dentifrice on the plaque inhibitory properties of an alcohol-free, high bioavailable 0.07% cetylpyridinium chloride (CPC) mouthrinse. MATERIALS AND METHODS: The study was a randomized, single-centre, examiner blind, four-period cross-over study involving 29 healthy subjects. Four treatment regimens were evaluated: (1) Toothbrushing with dentifrice followed by a water rinse (B-W, negative control); (2) Toothbrushing with dentifrice followed by a CPC mouthrinse use (B-CPC); (3) Toothbrushing with dentifrice followed by a water rinse and then a CPC mouthrinse use (B-W-CPC); and (4) Toothbrushing with dentifrice and waiting 60 min. prior to a CPC mouthrinse use (B-60 min.-CPC). Three days before the baseline exam of treatment periods, subjects were instructed to brush only the lingual surfaces of their teeth for up to 60 s twice daily. At baseline, subjects received a plaque exam using the Turesky modification of the Quigley-Hein index (MQH) followed by a polishing on the lingual and buccal surfaces of their teeth. During treatment periods, subjects were asked to brush only the lingual surfaces of their teeth with a standard fluoride dentifrice. Rinsing with 20 ml of the experimental CPC solution was done for 30 s twice daily. The evening before the last day of treatment periods (Day 4), subjects were asked to refrain from any oral hygiene, eating, and drinking after brushing. On Day 4, plaque was scored using the MQH Index. A 10-day wash-out of normal oral hygiene was allowed between each of the four treatment periods. The data were analysed using analysis of covariance for cross-over designs. RESULTS: Twenty-five to 29 subjects were evaluable at any given visit. With respect to unbrushed buccal and brushed lingual surfaces, all three CPC regimens had highly significantly (p < or = 0.0006) lower mean plaque scores than the B-W regimen, reductions ranging from 20% to 38% in magnitude. With respect to unbrushed surfaces, there was a significant difference between the B-CPC regimen and the B-60 min.-CPC regimen (p < 0.01) in favour of the latter regimen. No other pairwise treatment comparisons were statistically significant for unbrushed sites. Results for brushed surfaces and all sites combined showed that both the B-W-CPC and the B-60 min.-CPC groups reduced mean plaque levels significantly (p < or = 0.013) more than B-CPC. There were no statistically significant differences between B-W-CPC and B-60 min.-CPC for measurements of brushed, unbrushed, or all sites combined. CONCLUSIONS: Results show that the alcohol-free, 0.07% high bioavailable CPC rinse provides an additive anti-plaque benefit beyond toothbrushing with a standard fluoride dentifrice regardless of the regimen. Of the regimens, a water rinse between toothbrushing and CPC rinsing enhances therapeutic efficacy while fitting into the patient's typical oral hygiene routine.

Adult↗

Bacteriorhodopsin (bR) as an electronic conduction medium: current transport through bR-containing monolayers.

Studying electron transport (ET) through proteins is hampered by achieving reproducible experimental configurations, particularly electronic contacts to the proteins. The transmembrane protein bacteriorhodopsin (bR), a natural light-activated proton pump in purple membranes of Halobacterium salinarum, is well studied for biomolecular electronics because of its sturdiness over a wide range of conditions. To date, related studies of dry bR systems focused on photovoltage generation and photoconduction with multilayers, rather than on the ET ability of bR, which is understandable because ET across 5-nm-thick, apparently insulating membranes is not obvious. Here we show that electronic current passes through bR-containing artificial lipid bilayers in solid "electrode-bilayer-electrode" structures and that the current through the protein is more than four orders of magnitude higher than would be estimated for direct tunneling through 5-nm, water-free peptides. We find that ET occurs only if retinal or a close analogue is present in the protein. As long as the retinal can isomerize after light absorption, there is a photo-ET effect. The contribution of light-driven proton pumping to the steady-state photocurrents is negligible. Possible implications in view of the suggested early evolutionary origin of halobacteria are noted.

Bacteriorhodopsins↗

Efficacy and safety of a novel stabilized stannous fluoride and sodium hexametaphosphate dentifrice for dentinal hypersensitivity.

PURPOSE: Dentinal hypersensitivity is a common complaint among dental patients. Recently, a novel 0.454% stabilized stannous fluoride dentifrice containing sodium hexametaphosphate (SHMP) was introduced that offers a desensitizing benefit. This trial was conducted to assess the desensitizing efficacy of this new dentifrice relative to a sodium fluoride control dentifrice. METHODS AND MATERIAL: This was a double-blind, parallel-group, randomized clinical trial conducted according to the American Dental Association (ADA) Guidelines for the Acceptance of Products for the Treatment of Dentinal Hypersensitivity. Ninety subjects who met the entrance criteria were stratified based on age, gender, and baseline sensitivity scores and randomly assigned to either the stabilized stannous fluoride + SHMP dentifrice (Crest Pro-Health) or the sodium fluoride control dentifrice. Subjects were instructed to brush twice daily for eight weeks. Efficacy assessments were made, including tactile (Yeaple probe) and thermal (Schiff Air Index) sensitivity, and an oral soft tissue examination was conducted at baseline, week four, and week eight. RESULTS: The mean sensitivity score based on the Schiff Air Index for the stannous fluoride + SHMP group was statistically significantly lower than that of the control group, at both weeks four and eight (P < .0001). At week eight, the stannous fluoride + SHMP dentifrice group had an adjusted mean 44% lower than that of the control group. The mean tactile sensitivity score for the stannous fluoride + SHMP group was statistically significantly higher, indicating a reduction in sensitivity, than that of the control group, at both weeks four and eight (P < .0001). At week eight, the stannous fluoride + SHMP dentifrice group had a mean desensitizing improvement of 71% greater than the control. CONCLUSION: The stabilized stannous fluoride + SHMP dentifrice provided statistically significant reductions in dentinal hypersensitivity at four and eight weeks compared to the sodium fluoride control dentifrice.

Adolescent↗

Does naloxone alone increase resuscitation rate during cardiopulmonary resuscitation in a rat asphyxia model?

Cardiac arrest was induced with asphyxia to identify if naloxone alone increases resuscitation rate during cardiopulmonary resuscitation in a rat asphyxia model. The animals were randomized into either a saline group (Sal-gro, treated with normal saline 1 ml iv, n = 8), a low-dose naloxone group (treated with naloxone 0.5 mg/kg iv, n = 8), or a high-dose naloxone group (HN-gro, treated with naloxone 1 mg/kg iv, n = 8) in a blinded fashion during resuscitation. At the end of 10 minutes of asphyxia, cardiopulmonary resuscitation was started, and each drug was administered at the same time. The rate of restoration of spontaneous circulation was seen in 1 of 8, 3 of 8, and 7 of 8 animals in the Sal-gro, LN-gro, and HN-gro, respectively. The rate of restoration of spontaneous circulation in HN-gro was significantly higher than that in Sal-gro (P < .05). Naloxone (1 mg/kg) alone can increase resuscitation rate following asphyxial cardiac arrest in rats.

Animals↗

A comparison of transoesophageal cardiac pacing and epinephrine for cardiopulmonary resuscitation.

The use of cardiac pacing to deal with bradycardia is well established. There is debate as to the benefits during cardiopulmonary resuscitation (CPR). This study was performed to compare the effects of transoesophageal cardiac pacing and high-dose epinephrine on the benefits of cardiopulmonary resuscitation after asphyxial cardiac arrest in rats. Thirty Sprague-Dawley rats of both sexes were randomly selected to a saline group (Sal-gro, treated with normal saline 1 mL IV, n = 10), an epinephrine group (Epi-gro, treated with epinephrine 0.4 mg/kg IV, n = 10), or a pacing group (Pac-gro, treated with normal saline 1 mL IV combined with transoesophageal cardiac pacing, n = 10) in a blinded fashion during resuscitation after 10 minutes of asphyxial cardiac arrest. Manual chest compression was in all cases performed using the same methodology by the same personnel who was blinded to hemodynamic monitor tracings. The rate of restoration of spontaneous circulation was 1 (10%), 7 (70%), and 8 (80%) of 10 in Sal-gro, Epi-gro, and Pac-gro, respectively. The rate of ventilator withdrawal within 60 minutes after resuscitation in Pac-gro was higher than that of Epi-gro (8/8 vs 1/7, respectively; P = .001); the survival rate after 2 hours in Pac-gro was significantly higher than that in Epi-gro (7/8 vs 1/7, respectively; P = .01). The data demonstrate that both epinephrine and transoesophageal cardiac pacing are effective within 10 minutes of asphyxia in rats. It is worth noting that transoesophageal cardiac pacing produced a better outcome with respiration and longer survival time compared with epinephrine after restoration of spontaneous circulation.

Animals↗

Colonic fermentation may play a role in lactose intolerance in humans.

The results of our previous study suggested that in addition to the small intestinal lactase activity and transit time, colonic processing of lactose may play a role in lactose intolerance. We investigated whether colonic fermentation of lactose is correlated with lactose intolerance. After 28 Chinese subjects had undergone 1 glucose (placebo) and 2 lactose challenges, consistent lactose tolerant (n = 7) and intolerant (n = 5) subjects with no complaints after glucose administration were classified on the basis of the 6-h symptom scores. Before the challenges, fecal samples were collected for in vitro incubation with lactose. The incubation was carried out in a static system under anaerobic conditions for 5 h during which samples were taken for measurement of short-chain fatty acids, lactate, lactose, glucose, and galactose. Fecal bacterial composition was determined by fluorescent in situ hybridization. The tolerant and intolerant groups did not differ in the rate or degree of hydrolysis of lactose or production of glucose and galactose. The intolerant group produced d- and l-lactate, acetate, propionate, and butyrate significantly faster than the tolerant group. In the intolerant group, the amounts of acetate, propionate, butyrate, and l-lactate produced were higher than those in the tolerant group. Fecal bacterial composition did not differ between the 2 groups. The results indicate that the degree and rate of lactose hydrolysis in the colon do not play a role in lactose intolerance. However, after lactose is hydrolyzed, a faster and higher production of microbial intermediate and end metabolites may be related to the occurrence of symptoms.

Adult↗

[Expression of galectin-3 mRNA in gastric cancer with peritoneal metastasis].

OBJECTIVE: To search for the role of galectin-3 gene in gastric cancer with peritoneal metastasis. METHODS: Using real-time quantitative RT-PCR for detecting the expression of galectin-3 mRNA in 35 matched samples, including primary cancer lesions, lymph node lesions, peritoneal metastasis and adjacent noncancerous mucosa. ANOVA and SNK-q test were used. RESULTS: The levels of mean expression of galectin-3 mRNA in gastric cancer (385.639 +/- 98. 534), in peritoneal metastasis (368.589 +/- 93.431) and in lymph node metastasis (375.920 +/- 94.346) were significantly higher than that in noncancerous mucosa (2.158 +/- 0.896); there were statistically significant differences respectively (P < 0.05). However, the levels of the expression in gastric cancer, in peritoneal metastasis and in lymph node metastasis were shown to be of no significant differences by multiple comparison, P > 0.05. The expression level in the group of gastric cancer was noted to have positive correlation with that in the group of peritoneal metastasis. These data indicated that the expression levels of galectin-3 in gastric cancer were well correlated to peritoneal metastasis. CONCLUSION: The overexpression of galectin-3 in gastric cancer is well correlated with peritoneal metastasis. Galectin-3 mRNA level may serve as a biological marker in the pre-operative judgment on whether the gastric cancer has had peritoneal metastasis or has just the potential of metastasis.

Biomarkers, Tumor↗

[Effect of niti-alloy urethral stent in hypospadias repair].

OBJECTIVE: To evaluate the effect of niti-alloy urethral stent on the prevention of urethrocutaneous fistula and urethral stricture in hypospadias repair. METHODS: From January 2001 to December 2004, niti-alloy urethral stents were applied to repair congenital hypospadias in 63 patients. Among 63 patients, 49 (19 cases of proximal hypospadias, 22 cases of penoscrotal hypospadias and 8 cases of perineoscrotal hypospadias) received one-stage surgical managements of urethral reconstruction, and 10 underwent postoperative fistular repairs and 4 received repeated urethral reconstruction because of urethral stricture after hypospadias repair. RESULTS: All patients gained healing by first intention without fistula or urethral stricture. The stents were left indwelling in the neourethra for 2 months to 3 months to prevent stricture. The longest indwelling period was about 1 year. No dysuria or other discomfort occurred during this period. CONCLUSION: Niti-alloy urethral stent can effectively prevent the postoperative urethrocutaneous fistula and urethral stricture after hypospadias repair.

Adolescent↗

[A testing method of assessing the protein-removing effect of the contact lenses' protein -removing care solution].

OBJECTIVE: Testing the protein-removing effect of the protein-removing care solution on the protein precipitation of the soft contact lenses. METHOD: Soak the lenses into the artificial-tears to simulate the protein absorption, test the absorbency of cleaned protein at the wavelength of 280 nm by UV spectrophotometer, and compute the percentage of protein. RESULT: Testing results of the percentage of the cleaned protein are repeatable. CONCLUSION: This experimental method can be used to evaluate the cleaning effect of the protein- removing care solution, but still needs much improvements.

Contact Lens Solutions↗

[Protoplast culture and plant regeneration of the methionine resistant variant of Astragalus cicer L].

A protoplast-to-plant system for the methionine resistant variant of Astragalus cicer L. has been developed. The friable calli induced from stem segments of variant plants were used as materials for protoplast isolation through enzyme digestion. The effects of different media and plating densities on protoplast divisions and plant regeneration were studied. Sustained cell divisions and colony formation from the protoplasts of the methionine resistant cell line of Astragalus cicer L. were obtained by a DPD medium containing 2.0 mg/L 2,4- dichlorophenoxyacetic acid (2,4-D), 0.2 mg/L 6 -benzylaminopurine(6-BA), 0.3 mol/L mannitol, 200 mg/L casein hydrolysate and 2% (W/V) sucrose at a plating density of 2x10(5) /ml. The division frequency was 38.3%. At the same time, different dividing types of protoplasts were found. Organogenesis and shoot formation from the protoplast-derived calli were induced on MS medium supplemented with 0.5 mg/L NAA, 10 mg/L KT and 2% (W/V) sucrose. The protoplast-derived calli still expressed resistance to methionine. The protoplast to plant regeneration protocol developed in this study might provide the foundation for the resistant cell line as a parent for somatic hybridization.

Astragalus Plant↗

[Effect of probiotics and yogurt on colonic microflora in subjects with lactose intolerance].

OBJECTIVE: To study the effects of probiotics and yoghurt supplementation on colonic microflora in subjects with lactose intolerance (LI). METHODS: Eleven lactose intolerant volunteers determined by 25g lactose challenge test were recruited and given supplementation with Bifina capsule (with B. longum) and yogurt (with B. animalis, L. bulgaricus, S. thermophilus) for 14 days. The trial was divided into 3 phases: 7-day basal period, 14-day supplementation period and 7-day post-supplementation period. Two lactose challenge tests were performed 1 day before and 1 day after supplementation period respectively, and lactose intolerance symptoms were recorded with questionnaires. Five fecal samples were collected during the trial, and total bacteria and several main groups of bacteria in colon were analyzed by fluorescence in situ hybridization (FISH). The shift of Bifidobacterium species population in colon was analyzed by denaturing gradient gel electrophoresis (DGGE). RESULTS: It was found that LI symptom was alleviated significantly after supplementation (P < 0.05). The amount of total bacteria and the main groups of bacteria (Bifidobacteria, Bacteroides-Prevotella, Eubacteria, Ruminccocc, et al.) was significantly increased during the supplementation period (P < 0.05). The amount of Bifidobacteria during post-supplementation period was significantly higher than that of basal period (P < 0.05), while the amount of other several groups of bacteria decreased. The result of DGGE showed that the extraneous Bifidobacteria species from Bifina capsule and yoghurt could be detected in fecal samples during supplementation period, however there was diversity between volunteers. CONCLUSION: It was suggested that extraneous Bifidobacteria in Bifina capsule and yogurt could resist the effect of gastric acid and bile salt, and survive in colon. Supplementation of probiotics and yogurt could influence the colonic bacteria, and increase the number of main groups of colonic microflora, especially for Bifidobacteria, which could play important role in alleviating LI symptoms.

Adult↗

Classification of real and pseudo microRNA precursors using local structure-sequence features and support vector machine.

BACKGROUND: MicroRNAs (miRNAs) are a group of short (approximately 22 nt) non-coding RNAs that play important regulatory roles. MiRNA precursors (pre-miRNAs) are characterized by their hairpin structures. However, a large amount of similar hairpins can be folded in many genomes. Almost all current methods for computational prediction of miRNAs use comparative genomic approaches to identify putative pre-miRNAs from candidate hairpins. Ab initio method for distinguishing pre-miRNAs from sequence segments with pre-miRNA-like hairpin structures is lacking. Being able to classify real vs. pseudo pre-miRNAs is important both for understanding of the nature of miRNAs and for developing ab initio prediction methods that can discovery new miRNAs without known homology. RESULTS: A set of novel features of local contiguous structure-sequence information is proposed for distinguishing the hairpins of real pre-miRNAs and pseudo pre-miRNAs. Support vector machine (SVM) is applied on these features to classify real vs. pseudo pre-miRNAs, achieving about 90% accuracy on human data. Remarkably, the SVM classifier built on human data can correctly identify up to 90% of the pre-miRNAs from other species, including plants and virus, without utilizing any comparative genomics information. CONCLUSION: The local structure-sequence features reflect discriminative and conserved characteristics of miRNAs, and the successful ab initio classification of real and pseudo pre-miRNAs opens a new approach for discovering new miRNAs.

Animals↗