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Biomedical subjects

He Liu

Publications and source records attributed to He Liu.

At least 19 recordsLinked to original sources
PubMed2006

Magnetic resonance lactate and lipid signals in rat brain after middle cerebral artery occlusion model.

Proton magnetic resonance spectroscopy (1-H MRS) has revealed changes of metabolites in acute cerebral infarction. Although the drastic changes of lactate and N-acetyl-aspartate have been reported to be useful indicators of the ischemic damage in both humans and experimental animals, lipid signals are also detected by the short echo time sequence 1-5 days after ischemia. The objective of this study was to find a novel technique to isolate lactate signals from lipid signals in the ischemic brain. First, MRS was used to study the lipid and lactate components of a spherical phantom in vitro, and parameters were established to separate these components in vitro. Then, MR measurements were obtained from the brains of middle cerebral artery occlusion rats. All MR measurements were performed using a 7-T (300 MHz), 18.3-cm-bore superconducting magnet (Oxford Magnet Technologies) interfaced to a Unity INOVA Imaging System (Varian Technologies). T2-weighted images were obtained from a 1.0-mm-thick coronal section using a 3-cm field of view. It is well known that lipid has a shorter and lactate a longer T2 relaxation time. These distinct magnetic characteristics allowed us to separate the lactate signal from the lipid signal. Thus, adjustment of the echo time is essential to analyze the metabolites in acute cerebral infarction, which may be useful in both the clinic and laboratory.

Animals↗
PubMed2006

Mesenchymal stem cell-mediated functional tooth regeneration in swine.

Mesenchymal stem cell-mediated tissue regeneration is a promising approach for regenerative medicine for a wide range of applications. Here we report a new population of stem cells isolated from the root apical papilla of human teeth (SCAP, stem cells from apical papilla). Using a minipig model, we transplanted both human SCAP and periodontal ligament stem cells (PDLSCs) to generate a root/periodontal complex capable of supporting a porcelain crown, resulting in normal tooth function. This work integrates a stem cell-mediated tissue regeneration strategy, engineered materials for structure, and current dental crown technologies. This hybridized tissue engineering approach led to recovery of tooth strength and appearance.

Animals↗
PubMed2006

Dental pulp stem cells.

Postnatal stem cells have been isolated from a variety of tissues. These stem cells are thought to possess great therapeutic potential for repairing damaged and/or defective tissues. Clinically, hematopoietic stem cells have been successfully used for decades in the treatment of various diseases and disorders. However, the therapeutic potential of other postnatal stem cell populations has yet to be realized, because of the lack of detailed understanding of their stem cell characteristics at the cellular and molecular levels. Furthermore, there is limited knowledge of their therapeutic value at the preclinical level. Therefore, it is necessary to develop optimal strategies and approaches to overcome the substantial challenges currently faced by researchers examining the clinical efficacy of different postnatal stem cell populations. In this review, we introduce methodologies for isolating postnatal stem cells from human dental pulp and discuss their potential role in tissue regeneration.

Animals↗
PubMed2006

[Effect of pentachlorophenol (PCP) on bacterial community of an aerobic granular sludge estimated by T-RFLP].

Effect of pentachlorophenol (PCP) on COD and ammonium removal rates was investigated, and also changes of bacterial community within aerobic granular sludge were monitored by terminal restriction fragment length polymorphism (T-RFLP) technique. Compared with the removal rate of COD, the rate of ammonium removal is more sensitive to PCP. As the ammonium and COD removal rates decreased consistently, the bacterial genera within the aerobic granular sludge also decrease with the increase of PCP concentration. According to the response of PCP, the bacteria could be categorized into four groups as follows: (1) The most sensitive organisms such as Microbacterium, Streptococcus and two new kinds of microorganisms; (2) The more sensitive microorganisms such as Corynebacterium, Nevskia. and another unreported bacterium; (3) The lower sensitive organisms encompassing Mycoplasma, Exiguobacterium, and another microorganism which has not been reported yet; (4) The PCP-tolerant organisms, including microorganisms indicated by 13 TRFs are represented as 69, 71, 82, 175, 198, 241, 229, 232, 233, 240, 245, 269 and 449bp. To most noticeable, TRF relative areas of the microorganisms indicated by TRFs 82 bp and 175 bp achieve 22.7% and 13%, respectively, and become predominant within the aerobic granular sludge with the PCP concentration at 30 mg/L.

Bacteria, Aerobic↗
PubMed2005

A case of moyamoya disease presenting with chorea.

CASE REPORT: We describe a 15-year-old girl with moyamoya disease whose initial manifestation was chorea-like involuntary movements. T2-weighted magnetic resonance imaging showed high signal intensity lesions in the left frontal lobe, right parieto-occipital lobes, and frontal subcortical white matter. Single-photon emission computed tomography (SPECT) showed diffuse hypoperfusion of the whole brain. Bilateral direct and indirect cerebrovascular bypass surgeries were performed. Chorea disappeared 2 days after the surgery. Follow-up SPECT demonstrated increased cerebral perfusion in the bilateral frontal, temporal, and parietal regions. CONCLUSIONS: Chorea accompanied with moyamoya disease can be properly managed by revascularization surgery. Moyamoya disease should be remembered as being one of the differential diagnoses of chorea, which is treatable by surgery.

Adolescent↗
PubMed2005

Design, synthesis, and anti-tumor activity of (2-O-alkyloxime-3-phenyl)-propionyl-1-O-acetylbritannilactone esters.

The extracts of Inula britannica have anti-inflammatory, anti-bacterial, anti-hepatitic, and anti-tumor activities. Various sesquiterpene lactones with cytotoxic properties including 1-O-acetylbritannilactone (1) have been isolated from this Chinese medicinal plant. Eight derivatives of 1-O-acetylbritannilactone, (2-O-alkyloxime-3-phenyl)-propionyl-1-O-acetylbritannilactone esters were designed and synthesized. Four of these compounds were tested to show inhibitory activity on the growth of human leukemia HL-60 and cancer Bel-7402 cell lines.

Antineoplastic Agents↗
PubMed2005

MEPE is downregulated as dental pulp stem cells differentiate.

UNLABELLED: Previous studies on dental pulp cell culture have described heterogenous mixtures of cells that differentiate into odontoblasts and form mineralized dentin. OBJECTIVE: The aim of this study was to characterize the matrix extracellular phosphoglycoprotein (MEPE) expression by dental pulp stem cells (DPSC), related to cell differentiation. DESIGN: DPSC differentiation to form mineralized nodules was characterized by Alizarin red staining and micro-Raman spectroscopy. Osteogenesis SuperArray analysis was used to broadly screen for osteogenesis-related genes altered by DPSC differentiation. Relative levels of expression of MEPE and DSP were determined by semiquantitative RT-PCR and Western blot. RESULTS: Mineral analysis showed that as DPSC differentiated, they formed a carbonated hydroxyapatite mineral. Differentiation was initially marked by upregulation by Runx2, TGFbeta-related genes, EGFR and genes involved in collagen metabolism. ALP activity first increased, as DPSCs reached confluence but later decreased when cells further differentiated three weeks after confluence. MEPE was the only marker that was downregulated as DPSCs differentiated. CONCLUSION: DPSC differentiation can be characterized by downregulation of MEPE as other markers of DPSC differentiation, such as DSP, are upregulated. Expression of MEPE related to DSP and can be used to monitor DPSC as they are used for studies of odontoblast differentiation, tissue engineering or vital pulp therapy. The downregulation of MEPE as DPSC differentiate, suggests that MEPE is an inhibitor of mineralization.

Biomarkers↗
PubMed2005

Design, synthesis, and preliminary evaluation of gabapentin-pregabalin mutual prodrugs in relieving neuropathic pain.

As a part of a program for the development of specific analgesics in relieving neuropathic pain, the purpose of the present study was to investigate a new concept that involves the conjugation of two drugs, gabapentin and pregabalin, as mutual prodrugs using a chemical modification approach. A series of gabapentin-pregabalin diester compounds were synthesized using linear or branch bis-hydroxyl linkers. Their pharmacological properties for treating neuropathic pain were investigated in a rat model of chronic sciatic nerve constriction injury (CCI). In-vivo evaluation demonstrated that 1a and 1b composed of two gabapentin molecules as well as 3a composed of gabapentin and pregabalin with the short linear linker, were effective in reversing tactile allodynia in CCI rats. Compounds with longer or side-branched linkers showed lower efficiencies and severe adverse effects.

Amines↗
PubMed2005

Pharmacological profiles of an anticholinergic agent, phencynonate hydrochloride, and its optical isomers.

AIM: To comparatively study the pharmacological profiles of 3-methyl-3-azabicyclo(3,3,1)nonanyl-9-alpha-yl-alpha-cyclopentyl-alpha-phenyl-alpha-glycolate (phencynonate hydrochloride, CPG), an anticholinergic agent, and its enantiomers [R(-)-and S(+)-CPG]. METHODS: The affinity and relative efficacy were tested using radioligand-binding assay with muscarinic acetylcholine receptors from rat cerebral cortex. The pharmacological activities were assessed in three individual experiments: (1) potentiating the effect of subthreshold hypnotic dose of sodium pentobarbital; (2) inhibiting oxotremorine-induced salivation; and (3) inhibiting the contractile response to carbachol. RESULTS: The order of potency of phencynonate hydrochloride and its optical isomers to inhibit the binding of [3H]quinuclidinyl benzilate ([3H]QNB) was R(-)-CPG (K(i)=46.49+/-1.27 nmol/L)>CPG(K(i)=271.37+/-72.30nmol/L)>S(+)-CPG(K(i)=1263.12+/-131.64 nmol/L). The results showed that R(-)-CPG had the highest affinity to central muscarinic receptors among the three compounds, but did not show any central depressant effects at dose from 10.00 to 29.15 mg/kg. CPG increased the effects of subthreshold hypnotic dose of sodium pentobarbital induced-sleeping [the ED50+/-95% LC value was 21.06+/-3.04 mg/kg]. CPG and R(-)-CPG displayed nearly equipotent effect in depressing oxotremorine-induced salivation [the ED50 +/-95% LC for R(-) and CPG were 1.10+/-0.28 and 1.07+/-0.15 mg/kg, respectively], and the contractile response to carbachol (pA(2) values for R (-) and CPG were 6.84 and 6.80, respectively). S(+)-CPG presented the lowest anticholinergic profiles, but could potentate effects of its enantiomers in some manner. CONCLUSIONS: These data suggested that R(-)-CPG acted as an eutomer in racemate and a competitive antagonist to acetylcholine muscarinic receptors, but S(+)-CPG was less active in comparison to R(-)-CPG and its racemate. The central depressant effects of R(-)-CPG and S(+)-CPG were lower in comparison to its racemate.

Animals↗
PubMed2005

Metastatic renal cell carcinoma mimicking pituitary adenoma: case report.

A 54-year-old man, with a past history of renal cell carcinoma, presented with bitemporal visual field defect, hyponatremia, and diabetes insipidus. Endocrinological examination revealed panhypopituitarism. Computed tomography and magnetic resonance imaging showed an intrasellar mass with suprasellar extension. The initial radiological impression was pituitary adenoma. The tumor was decompressed via the transsphenoidal route. Histological examination revealed metastatic renal cell carcinoma. The clinical characteristics of metastatic pituitary carcinoma appear to be panhypopituitarism, and neuroimaging findings of strong enhancement of the tumor and bony destruction without marked sellar enlargement.

Carcinoma, Renal Cell↗
PubMed2004

Design, synthesis, and biological evaluation of novel 4-alkylamino-1-hydroxymethylimidazo[1,2-a]quinoxalines as adenosine A(1) receptor antagonists.

A series of 4-alkylamino-1-hydroxymethylimidazo[1,2-a]quinoxalines have been synthesized and evaluated for their adenosine A(1) receptor inhibitory activity in the radioligand binding assays. The compounds were tested for the inhibition percent (IP) and the affinity toward A(1)AR (K(i)) that IP were more than 90% in the nanomolar range. 4-Cyclopentylamino-7,8-dichloro-1-hydroxymethylimidazo[1,2-a]quinoxaline 18 is the most potent compound in this series, having K(i)=7nM, which is remarkably higher than that of IRFI-165 (K(i)=48). 1-Hydroxymethyl groups of the tricyclic heteroarmatic compounds displayed the potent affinities toward A(1)AR.

Adenosine A1 Receptor Antagonists↗
PubMed2004

Studies on 1-O-acetylbritannilactone and its derivative, (2-O-butyloxime-3-phenyl)-propionyl-1-O-acetylbritannilactone ester.

The crystal structures of 1-O-acetylbritannilactone 6 isolated from Inula britannica, and its derivative (2-O-butyloxime-3-phenyl) propionyl 1-O-acetylbritannilactone ester 7 are reported. The structure of synthesized derivative 7 was established by spectroscopic methods. Both compounds inhibited the growth of human HL-60, Bel-7402 cell lines and compound 7 had the stronger cytotoxic activity.

Antineoplastic Agents↗
PubMed2004

A novel tri-primer PCR method (TP-PCR) for rapid construction of fpg gene.

A novel tri-primer polymerase chain reaction method (TP-PCR) was developed for the construction of a fused fpg gene, in which no endonuclease and ligase were used. Instead, two templates and three specifically designed primers were applied. Results showed that pheB and gfp genes, which encodes the catechol 2, 3-dioxygenase and the green fluorescent protein (GFP), respectively, were successfully fused into an fpg gene through the rapid TP-PCR system, indicating that TP-PCR method could be a useful tool for DNA fragment fusion in which no proper endonuclease sites were available.

Amino Acid Sequence↗
PubMed2004

Pollution characteristics of the recent sediments in the Hangzhou section of the Grand Canal, China.

Spatial distribution of heavy metals, arsenic and organic matter in recent sediments in the Hangzhou section of the Grand Canal and their relationships were analyzed. The results showed that the concentrations of heavy metals and organic matters varied widely along the canal, and the average geological accumulation factors decreased in the following orders: organic carbon(2.6), zinc(2.1), cadmium (2.0), copper(1.5), lead(1.1), nitrogen(0.9), mercury (0.8), phosphorus(0.4), arsenic(0.2) and chromium(0). Content of heavy metals and organic carbon in the top 10 cm layer were lower than that of lower layers, except for mercury and organic carbon in the S9 section. Contents of organic carbon in the top 50 cm layer of the mud sediments are significantly higher than those underneath. In the bottom mud layer, there is a concentration peak of the pollutants. In the mud sediments of the canal, cadmium mainly occurred in the Fe and Mn oxide fraction, copper in the organic fraction, lead in the Fe and Mn oxide fraction, and zinc in the carbonate and the Fe and Mn oxide fraction.

Arsenic↗
PubMed2004

[Construction of a fused fpg gene by using TP-PCR method].

TP-PCR,a method developed for fusion gene construction without the use of endonuclease and ligase, was performed to construct a fused fpg gene. The TP-PCR reaction system contained three primers and two templates and resulting PCR product, fused fpg gene, consisted of three sections: pheB gene, which was responsible for catechol 2,3-dioxygenase, gfp gene for GFP protein and the intermediate ligation segment which was designed for the correct expression of the fusion gene. The result in this paper showed that the TP-PCR method is one of rapid and convenient methods for fused gene construction.

Catechol 2,3-Dioxygenase↗
PubMed2004

[Preliminary application of PCR-DGGE to analyzing microbial diversity in biofilters treating air loaded with ammonia].

As a new DNA fingerprinting technique, denaturing gradient gel electrophoresis (DGGE) can be used to analyze the microbial diversity in different environmental samples. Three biofilters treating air loaded with ammonia will be studied with respect to microbial diversity by applying cultivation-independent molecular methods DGGE. The principal objectives of this paper include the development and application of a suitable set of molecular tools to deliver information about the possible microbial community changes within carriers during treatment of ammonia-contaminated gas. Carriers were sampled at different time during operation of biofilters. After extraction and purification of the genomic DNA, the 16S rRNA genes (V3 region) were amplified by using the specific primers. These amplified DNA fragments were then separated by paralleled DGGE. The profile of DGGE showed that the same carrier at different time had the different bands' patterns. The structural diversity of the microbial community was examined by the Shannon index of general diversity H. Shannon indexes of three kinds of carriers all showed a decrease with time, which had a similar trend to NH3 removal efficiency.

Air Pollutants↗
PubMed2003

A novel cytoplasmic tail MXXXL motif mediates the internalization of prostate-specific membrane antigen.

Prostate-specific membrane antigen (PSMA) is a transmembrane protein expressed at high levels in prostate cancer and in tumor-associated neovasculature. In this study, we report that PSMA is internalized via a clathrin-dependent endocytic mechanism and that internalization of PSMA is mediated by the five N-terminal amino acids (MWNLL) present in its cytoplasmic tail. Deletion of the cytoplasmic tail abolished PSMA internalization. Mutagenesis of N-terminal amino acid residues at position 2, 3, or 4 to alanine did not affect internalization of PSMA, whereas mutation of amino acid residues 1 or 5 to alanine strongly inhibited internalization. Using a chimeric protein composed of Tac antigen, the alpha-chain of interleukin 2-receptor, fused to the first five amino acids of PSMA (Tac-MWNLL), we found that this sequence is sufficient for PSMA internalization. In addition, inclusion of additional alanines into the MWNLL sequence either in the Tac chimera or the full-length PSMA strongly inhibited internalization. From these results, we suggest that a novel MXXXL motif in the cytoplasmic tail mediates PSMA internalization. We also show that dominant negative micro2 of the adaptor protein (AP)-2 complex strongly inhibits the internalization of PSMA, indicating that AP-2 is involved in the internalization of PSMA mediated by the MXXXL motif.

Adaptor Protein Complex 2↗