Biomedical subjects

Yuan Li

Publications and source records attributed to Yuan Li.

At least 37 records · Page 2Linked to original sources

PubMed2006

N6-Cycloalkyl-2-substituted adenosine derivatives as selective, high affinity adenosine A1 receptor agonists.

A series of new selective, high affinity A(1)-AdoR agonists is reported. Compound 23 that incorporated a carboxylic acid functionality in the 4-position of the pyrazole ring displayed K(iL) value of 1 nM for the A(1)-AdoR and >5000-fold selectivity over the A(3) and A(2A)-AdoRs. In addition, compound 19 that incorporated a carboxamide functionality in the 4-position of the pyrazole ring displayed subnanomolar affinity for the A(1)-AdoR (K(iL)=0.6 nM) and >600-fold selectivity over the A(3) and A(2A)-AdoRs.

Adenosine↗

PubMed2006

Precision measurement of ultralow losses of an asymmetric optical microcavity.

The losses of the transmission, absorption, and scattering of optical mirrors govern the extraction efficiency of a nonclassical state that is generated inside a cavity. By measuring the reflectivities and transmittances and the matching factors from both sides of a super-mirror-made microcavity at various mode-matching efficiencies, the transmission losses and the unwanted losses, including the absorption and scatter losses, of the left and right cavity mirrors were both determined at the parts-per-million level.

Journal Article↗

PubMed2006

Natural killer cell inhibits human immunodeficiency virus replication in chronically infected immune cells.

Natural killer (NK) cells are a crucial component of the host innate immune system. We investigated the noncytolytic anti-human immunodeficiency virus (HIV) activity of NK cells in chronically HIV-infected immune cells. Supernatants collected from NK cell cultures (both primary NK cells and NK cell lines, YTS and NK 92) inhibited HIV activation in peripheral blood mononuclear cells (PBMCs) from HIV-infected subjects. NK supernatants (NK SN) also suppressed tumor necrosis factor (TNF)-alpha-induced HIV activation in chronically infected cell lines (U1 and ACH-2 cells). The antibody to interferon (IFN)-gamma blocked NK SN-mediated anti-HIV effect, while the antibodies to CC-chemokines had no impact on NK SN-mediated HIV inhibition in U1 and ACH-2 cells. Investigation of mechanism(s) responsible for the NK action showed that NK SN inhibited TNF-alpha-mediated activation of HIV-long-terminal repeat (LTR), and upregulated the expression of signal transducer and activator of transcription (STAT)-1 and phosphorylated P38 mitogen-activated protein kinase (MAPK). The P38 MAPK inhibitor (SB 203580) blocked NK SN-mediated HIV inhibition. These data provide compelling evidence that NK cells have a critical role in controlling HIV activation in the reservoirs.

HIV↗

PubMed2006

Intracellular peptides of natriuretic peptide receptor-C inhibit vascular hypertrophy via Gqalpha/MAP kinase signaling pathways.

OBJECTIVE: The present studies were undertaken to investigate if the activation of natriuretic peptide receptor-C (NPR-C) that has been shown to inhibit cell proliferation could also modulate the hypertrophic responses of vasoactive peptides in A10 vascular smooth muscle cells (VSMC). METHODS: For these studies A10 VSMC were incubated in the presence of angiotensin II (AngII), endothelin (ET-1) or arginine vasopressin (AVP) alone or in combination with C-ANP4-23 or NPR-C peptides for 24 h and were used for Western blotting and [3H]leucine incorporation. The different peptide fragments used were K461KYRITIERRNH472 (peptide-1) and H481RELREDSIRSH492 (peptide-3) with complete Gi activator sequences and R469RNHQEESNIGK480 (peptide-2) and I465TIERRNH472 (peptideY) with partial Gi activator sequences. The other peptide used had no structural specificity, (Q473EESNIGK480; peptide X) or was the scrambled peptide control for peptide-1 (ITIYKKRRNHRE; peptide Z). RESULTS: AngII, ET-1 and AVP significantly stimulated protein synthesis in these cells as determined by 3H-leucine incorporation, which was inhibited by peptides 1, 2 and 3 and not by peptides X, Y or Z in a concentration-dependent manner with an apparent Ki between 1-10 nM. In addition, C-ANP4-23 also inhibited protein synthesis stimulated by AngII, ET-1 and AVP; whereas basal protein synthesis in these cells was not inhibited by C-ANP4-23 or by the peptide fragments. Furthermore, AngII-, AVP- and ET-1-induced stimulation of protein synthesis was inhibited by PD98059 (MEK inhibitor) and wortmannin (P13K inhibitor) and this inhibition was potentiated by peptide-1. In addition, peptide-1 was also able to inhibit vasoactive peptide-induced phosphorylation of ERK1/2 and AKT and enhanced the expression of Gqalpha protein in these cells. CONCLUSIONS: These data suggest that C-ANP4-23 and small peptide fragments containing 12 amino acids from different regions of cytoplasmic domain of NPR-C could modulate vasoactive peptide-stimulated protein synthesis through Gqalpha/MAP kinase/P13K and AKT pathways.

Androstadienes↗

PubMed2006

Small cytoplasmic domain peptides of natriuretic peptide receptor-C attenuate cell proliferation through Gialpha protein/MAP kinase/PI3-kinase/AKT pathways.

The present studies were undertaken to investigate the effect of C-atrial natriuretic peptide (ANP)(4-23) and several peptide fragments containing 12 amino acids from different regions of the cytoplasmic domain of natriuretic peptide receptor (NPR)-C on cell proliferation in the absence or presence of angiotensin (ANG) II, endothelin (ET)-1, and arginine vasopressin (AVP) in A-10 vascular smooth muscle cells (VSMC). The peptide fragments used have either complete G(i) activator sequences K(461)-H(472) (peptide 1) and H(481)-H(492) (peptide 3) or partial G(i) activator sequences R(469)-K(480) (peptide 2) and I(465)-H(472) (peptide Y) with truncated COOH or NH(2) terminus, respectively. The other peptide used had no structural specificity (Q(473)-K(480), peptide X) or was the scrambled peptide control for peptide 1 (peptide Z). ANG II, ET-1 and AVP significantly stimulated DNA synthesis in these cells as determined by [(3)H]thymidine incorporation that was inhibited by peptides 1, 2, and 3 and not by peptides X, Y, and Z in a concentration-dependent manner, with an apparent K(i) between 1 and 10 nM. In addition, C-ANP(4-23), which interacts with NPR-C, also inhibited DNA synthesis stimulated by vasoactive peptides; however, the inhibition elicited by C-ANP(4-23) was not additive with the inhibition elicited by peptide 1. On the other hand, basal DNA synthesis in these cells was not inhibited by C-ANP(4-23) or the peptide fragments. Furthermore, vasoactive peptide-induced stimulation of DNA synthesis was inhibited by PD-98059 and wortmannin, and this inhibition was potentiated by peptide 1. In addition, peptide 1 also inhibited vasoactive peptide-induced phosphorylation of ERK1/2 and AKT and enhanced expression of G(i)alpha proteins. These data suggest that C-ANP(4-23) and small peptide fragments containing 12 amino acids irrespective of the region of the cytoplasmic domain of NPR-C inhibit proliferative responses of vasoactive peptides through G(i)alpha protein and MAP kinase/phosphatidylinositol 3-kinase/AKT pathways.

Amino Acid Sequence↗

PubMed2006

[Successful clinical pregnancy of cryopreserved human oocytes after vitrification].

OBJECTIVE: To assess the feasibility and clinical value of cryopreservation of human oocytes. METHODS: Human oocytes were collected during stimulated cycle and then vitrificated with cryoloop. Surviving oocytes were thawed and then inseminated by intracytoplasmic sperm injection (ICSI). The fertilized oocytes were further cultured in vitro for 48 - 72 hours. High-quality embryos were transferred to the patients of infertility with informed consent. RESULTS: A total of 235 oocytes were vitrificated and thawed. The survival and fertilization rates of the oocytes were 71.9% and 72.5% respectively. Forty-one embryos were transferred to 11 patients. Two of the 11 patients achieved pregnancy, one of which gave birth of 2 healthy female twin babies and the other was at the 16 th week of pregnancy. The mother and babies were all healthy. CONCLUSION: Human oocyte vitrification is safe and feasible.

Adult↗

PubMed2006

Characterization of TRIM5alpha trimerization and its contribution to human immunodeficiency virus capsid binding.

The coiled-coil domain of the tripartite motif (TRIM) family protein TRIM5alpha is required for trimerization and function as an antiretroviral restriction factor. Unlike the coiled-coil regions of other related TRIM proteins, the coiled coil of TRIM5alpha is not sufficient for multimerization. The linker region between the coiled-coil and B30.2 domains is necessary for efficient TRIM5alpha trimerization. Most of the hydrophilic residues predicted to be located on the surface-exposed face of the coiled coil can be altered without compromising TRIM5alpha antiviral activity against human immunodeficiency virus (HIV-1). However, changes that disrupt TRIM5alpha trimerization proportionately affect the ability of TRIM5alpha to bind HIV-1 capsid complexes. Therefore, TRIM5alpha trimerization makes a major contribution to its avidity for the retroviral capsid, and to the ability to restrict virus infection.

Antiviral Restriction Factors↗

PubMed2006

Requirements for capsid-binding and an effector function in TRIMCyp-mediated restriction of HIV-1.

In owl monkeys, a retrotransposition event replaced the gene encoding the retroviral restriction factor TRIM5alpha with one encoding TRIMCyp, a fusion between the RING, B-box 2 and coiled-coil domains of TRIM5 and cyclophilin A. TRIMCyp restricts human immunodeficiency virus (HIV-1) infection by a mechanism dependent on the interaction of the cyclophilin A moiety and the HIV-1 capsid protein. Here, we show that infection by retroviruses other than HIV-1 can be restricted by TRIMCyp, providing an explanation for the evolutionary retention of the TRIMCyp gene in owl monkey lineages. The TRIMCyp-mediated block to HIV-1 infection occurs before the earliest step of reverse transcription. TRIMCyp-mediated restriction involves at least two functions: (1) capsid binding, which occurs most efficiently for trimeric TRIMCyp proteins that retain the coiled-coil and cyclophilin A domains, and (2) an effector function that depends upon the B-box 2 domain.

Animals↗

PubMed2006

Single-nucleotide polymorphism genotyping by nanoparticle-enhanced surface plasmon resonance imaging measurements of surface ligation reactions.

A sensitive method for the analysis of single nucleotide polymorphisms (SNPs) in genomic DNA that utilizes nanoparticle-enhanced surface plasmon resonance imaging (SPRI) measurements of surface enzymatic ligation reactions on DNA microarrays is demonstrated. SNP identification was achieved by using sequence-specific surface reactions of the enzyme Taq DNA ligase, and the presence of ligation products on the DNA microarray elements was detected using SPRI through the hybridization adsorption of complementary oligonucleotides attached to gold nanoparticles. The use of gold nanoparticles increases the sensitivity of the SPRI so that single bases in oligonucleotides can be successfully identified at a concentration of 1 pM. This sensitivity is amply sufficient for performing multiplexed SNP genotyping by using multiple PCR amplicons and should also allow for the direct detection and identification of SNP sequences from 1 pM unamplified genomic DNA samples with this array-based and label-free SPRI methodology. As a first example of SNP genotyping, three different human genomic DNA samples were screened for a possible point mutation in the BRCA1 gene that is associated with breast cancer.

DNA↗

PubMed2006

Specific recognition and accelerated uncoating of retroviral capsids by the TRIM5alpha restriction factor.

The host restriction factor TRIM5alpha mediates species-specific, early blocks to retrovirus infection; susceptibility to these blocks is determined by viral capsid sequences. Here we demonstrate that TRIM5alpha variants from Old World monkeys specifically associate with the HIV type 1 (HIV-1) capsid and that this interaction depends on the TRIM5alpha B30.2 domain. Human and New World monkey TRIM5alpha proteins associated less efficiently with the HIV-1 capsid, accounting for the lack of restriction in cells of these species. After infection, the expression of a restricting TRIM5alpha in the target cells correlated with a decrease in the amount of particulate capsid in the cytosol. In some cases, this loss of particulate capsid was accompanied by a detectable increase in soluble capsid protein. Inhibiting the proteasome did not abrogate restriction. Thus, TRIM5alpha restricts retroviral infection by specifically recognizing the capsid and promoting its rapid, premature disassembly.

Animals↗

PubMed2006

Loss of heterozygosity of Kras2 gene on 12p12-13 in Chinese colon carcinoma patients.

AIM: To study the loss of heterozygosity (LOH) on 12p12-13 in Chinese colon carcinoma patients. METHODS: DNA was extracted from 10 specimens of cancer tissue, 10 specimens of adjacent tissue and 10 specimens of normal tissue, respectively. LOH of Kras2 gene was analyzed by polymerase chain reaction (PCR) and denaturing polyacrylamide gel electrophoresis using 11 microsatellite markers on 12p-12-13. RESULTS: LOH of Kras gene was detected at least on one marker of 12p-12-13 in 30% (3/10) of adjacent tissue specimens. The highest frequency of LOH was identified on D12S1034 in 28.57% (2/7) of adjacent tissue specimens. LOH was detected at least on one marker of 12p12-13 in 60% (6/10) of carcinoma tissue specimens, the most frequent LOH was found on D12S1034 and D12S1591 in 42.86% (3/7) of carcinoma tissue specimens. LOH was detected in 30% (3/10) of carcinoma tissue specimens, 30% (3/10) of adjacent tissue specimens, and no signal in 1% (1/0) carcinoma tissue specimen. The occurrence of LOH did not correlate with sex, age, tumor size and lymph node metastasis. CONCLUSION: Genomic instability may occur on 12p-12-13 of Kras2 gene in the development and progression of colon carcinoma. The high LOH of Kras2 gene may directly influence the transcription and translation of wild type Kras2 gene.

Asian People↗

PubMed2006

Differentiation between tuberculosis and primary tumors in the adrenal gland: evaluation with contrast-enhanced CT.

The aim of the present study is to determine imaging criteria for differentiating tuberculosis from primary tumors in the adrenal gland on contrast-enhanced CT. Non-contrast and contrast-enhanced CT features in 108 patients with adrenal tuberculosis (n = 34) and primary tumor (n = 74) were retrospectively assessed for the location, size, calcification and enhancement patterns. The primary tumors included 41 adenomas, 11 pheochromocytomas, 4 carcinomas, 3 lymphomas, 6 myelolipomas, 6 ganglioneuromas, 2 neurilemmomas and 1 ganglioneuroblastoma. Biochemical investigation was performed for all patients. Of the tuberculosis cases, 31 (91%) invaded with bilateral involvement, while 7 (9%) of the primary tumors invaded with bilateral involvement (P < 0.001). Tuberculosis often showed calcification (20 of 34; 59%), whereas primary tumors infrequently showed calcification (6 of 74; 8%; P < 0.001). Low attenuation in the center with peripheral rim enhancement was more commonly seen in tuberculosis (16 of 34; 47%) than in primary tumors (7 of 74; 9%; P < 0.001). In the determination of tuberculosis, the highest sensitivity (91%) and accuracy (91%) were obtained with bilateral involvement, and the highest specificity (99%) was obtained with the contour preserved. In the determination of primary tumors using a combination of having unilateral involvement and being mass-like, the outcome was a sensitivity of 91%, specificity of 94% and accuracy of 92%. CT findings can differentiate tuberculosis from a primary tumor of the adrenal glands with high sensitivity and an acceptable specificity when combined with the endocrinological examination.

Adolescent↗

PubMed2006

A novel partial agonist of the A(1)-adenosine receptor and evidence of receptor homogeneity in adipocytes.

This study characterizes the receptor binding and functional effects of CVT-3619 [2-{6-[((1R,2R)-2-hydroxycyclopentyl)-amino]purin-9-yl}(4S,5S,2R,3R)-5-[(2-fluorophenylthio)methyl]-oxolane-3,4-diol], a novel N(6)-5' -substituted adenosine analog and A(1) -adenosine receptor (A(1) AdoR) agonist, on rat epididymal and inguinal adipocytes and on the isolated heart and compares these effects with those caused by the full agonist N(6) -cyclopentyladenosine (CPA). In addition, the hypothesis that adipocyte A(1)AdoR are a heterogeneous population with regard to their affinities for ligands was tested. CVT-3619 was 10-100-fold selective for A(1)AdoR versus other AdoR and bound to adipocyte membranes with high (K(H) = 14 nM) and low (K = 5.4 microM) affinities. CVT-3619 reduced cyclic AMP content and release of nonesterified fatty acids from epididymal adipocytes with IC(50) values of 6 and 44 nM, respectively. CVT-3619 was a partial agonist relative to CPA to reduce lipolysis in epididymal and inguinal adipocytes. CVT-3619 did not change atrial rate in rat heart and caused a small (6-ms) prolongation of the stimulus-to-His bundle interval without causing atrioventricular block in guinea pig heart (effects mediated by A(1)AdoR), whereas CPA caused atrioventricular block and near cessation of atrial electrical activity. CVT-3619 increased coronary conductance (effect mediated by A(2A)AdoR) only at concentrations > or =10 microM. Rat epididymal adipocyte A(1)AdoR had similar affinities for the antagonist 8-cyclopentyl-1,3-dipropylxanthine in the presence of three dissimilar A AdoR agonists (2-chloro-N(6) -cyclopentyladenosine, N(6) -sulfophenyladenosine, and N-5' -ethylcarboxamidoadenosine) as determined by Schild analysis. It was concluded that rat epididymal adipocyte A(1)AdoR are a homogeneous receptor population with regard to affinities for ligands and that CVT-3619 is a partial agonist with selectivity for A(1)AdoR and inhibition of lipolysis.

Adenosine↗

PubMed2006

Disruption of the ste22 gene encoding a glycosyltransferase and its function in biosynthesis of Ebosin in Streptomyces sp. 139.

Streptomyces sp.139 produces an exopolysaccharide (EPS) designated Ebosin with remarkable anti-rheumatic arthritis activity in vivo. The ste (Streptomyces eps) gene cluster required for Ebosin biosynthesis has been identified. According to similarities with other proteins in the database, ste22 shows high homology with glycosyltransferases originated from different microorganisms. In this study, the ste22 gene was disrupted by double crossover via homologous recombination. The EPS produced by the mutant strain Streptomyces sp.139 (ste22(-)) has a different monosaccharide composition profile in comparison with that of Ebosin. This derivative of Ebosin retained the original antagonistic activity of IL-1R in vitro but lost the bioactivities of anti-inflammation and pain relief in vivo.

Antirheumatic Agents↗

PubMed2006

Clinical study of Jiawei Huangqi Guizhi Wuwu Decoction in preventing and treating peripheral neuro-sensory toxicity caused by oxaliplatin.

OBJECTIVE: To evaluate the efficacy of Jiawei Huangqi Guizhi Wuwu Decoction (JHGWD) in treating neuro-sensory toxicity induced by oxaliplatin. METHODS: A randomized controlled self-crossover trial was performed. Thirty-one patients were randomly divided into AB and BA groups. Patients in A cycle belonged to the treated group, who were treated with chemotherapy combined with oxaliplatin plus JHGWD. Patients in B cycle belonged to the control group and were treated with chemotherapy alone. The peripheral neuro-sensory toxicity was observed and analyzed. RESULTS: The main neurotoxicity was cold-induced paresthesia after the use of oxaliplatin, which included hyperaesthesia, chill, anaesthesia in the extremities, electrified sensation, formication, foreign body sensation and pain that might be exacerbated by exposure to cold. Twenty patients (64.5%) suffered from neuro-sensory toxicity in the treated group and 27 cases (87.1%) in the control group. Symptoms were more serious and lasted longer in the control group than those in the treated group (P < 0.01). CONCLUSION: JHGWD could prevent and reduce the occurrence and intensity of acute peripheral neuro-sensory toxicity caused by oxaliplatin.

Adult↗

PubMed2006

Confocal microscopic analysis of the spindle and chromosome configurations of human oocytes matured in vitro.

OBJECTIVE: To assess the potential effects of in vitro maturation (IVM) of human oocytes on the meiotic spindle and associated chromosome configuration. DESIGN: Prospective study. SETTING: Hospital-based IVF center. PATIENT(S): Patients with polycystic ovary syndrome (PCOS) undergoing unstimulated and stimulated cycles of oocyte retrieval. INTERVENTION(S): Immature (germinal vesicle and metaphase I) and mature (metaphase II) oocytes were collected from PCOS patients. The meiotic spindle and chromosome configurations in oocytes matured in vitro and in vivo were studied by confocal microscopy, with fluorescent labeling techniques for visualization of both microtubules and chromatin. MAIN OUTCOME MEASURE(S): Meiotic spindle and associated chromosome configurations. RESULT(S): Oocytes can develop to the metaphase II stage after IVM. Confocal microscopic observations revealed that the oocytes matured in vitro had a higher frequency of abnormal meiotic spindle and chromosomal alignment morphology than in vivo-matured oocytes. These abnormalities included a partial or total disorganization of the meiotic spindle microtubules. Abnormal chromosome organization included dispersal of chromosomes or chromosomes with an aberrant, less-condensed appearance. The proportions of abnormality in spindle and chromosome configurations in oocytes matured in vitro were 43.7% and 33.3%, respectively, which was significantly higher than in those oocytes matured in vivo (13.6% and 9.1%). CONCLUSION(S): In vitro maturation can have deleterious effects on the organization of the meiotic spindle and chromosome alignment of human oocytes. This result suggests one possible explanation for the reduced developmental potential of oocytes matured in vitro compared with those matured in vivo. This is likely a contributing factor to the overall lower clinical outcomes observed after IVM and ET.

Adult↗

PubMed2006

Glucocorticoid receptor subunit gene expression in parotid gland and adenomas.

OBJECTIVE: The present study was undertaken to investigate the expressions of glucocorticoid receptor-alpha (GR-alpha) and -beta (GR-beta) messenger RNA (mRNA) in normal parotid and adenoma tissues. STUDY DESIGN AND SETTING: Eighteen pleomorphic adenomas of the parotid gland and 12 parotid gland tissues adjacent to adenomas were studied by using real-time fluorescent quantitative reverse-transcription polymerase chain reaction method. RESULTS: The expression of both GR-alpha and GR-beta mRNA in parotid adenoma were higher than that in normal parotid glands (P<0.001), the GR-alpha/GR-beta ratios in parotid adenoma were lower than that in normal parotid glands (P<0.001), and there were no differences of both GR-alpha and GR-beta mRNA as well as GR-alpha/GR-beta ratios in male and female (P>0.05). CONCLUSION AND SIGNIFICANCE: Our results showed that the mRNA expression of both GR-alpha and GR-beta were detectable in all studied specimens. The mRNA levels of these 2 GRs were higher, whereas the GR-alpha/GR-beta ratios were lower in adenomas tissues than that in the parotid gland; no differences of these 2 GRs as well as GR-alpha/GR-beta ratios were found between sexes. These data indicate that the relationship between the expressions of GRs and the clinical significance in parotid adenomas need further and profound investigation.

Adenoma, Pleomorphic↗

PubMed2006

Hepatoprotective sesquiterpene glycosides from Sarcandra glabra.

Six new sesquiterpene glycosides, compounds 1-6, with eudesmanolide, elemanolide, lindenane, and germacranolide sesquiterpene aglycons, along with one known compound, chloranoside A (7), have been isolated from the whole plant of Sarcandra glabra. The structures of 1-6 were elucidated by chemical and spectroscopic methods including (1)H-(1)H COSY, HMQC, HMBC, and NOESY NMR experiments. In addition, compounds 1-7 showed pronounced hepatoprotective activities against D-galactosamine-induced toxicity in WB-F344 rat hepatic epithelial stem-like cells.

Animals↗