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Biomedical subjects

Jun Guo

Publications and source records attributed to Jun Guo.

87 records · Page 5Linked to original sources
PubMed2003

[Determination of tetramine in plasma by gas chromatography].

A method was developed to measure the tetramine in plasma by liquid-liquid extraction and GC-NPD with the limit of detection (LOD) 1.5 pg and the limit of quantity 10 ng/ml. The linear range was 0.1-5 micrograms/ml with a correlation coefficient of 0.999. Recoveries for three concentrations of tetramine were 96.0%, 107.0%, 106.8%. The intra-day precision were 9.6%, 9.8%, 7.8%, the inter-day precision were 6.6%, 8.5%, 6.2%. Tetramine in plasma was stable up to 5 months at -4 degrees C.

Bridged-Ring Compounds↗
PubMed2003

[An improved high performance liquid chromatography method for determination of 1-hydroxypyrene in urine].

A method for determination of 1-hydroxypyrene in urine by alkaline hydrolysis and high performance liquid chromatography was improved and validated. The conjugated 1-hydroxypyrene in urine samples was decomposed by sodium hydroxide. The urinary 1-hydroxypyrene were extracted by dichloromethane, separated on reverse phase C18 and detected by fluorescence detector. Internal standard method was applied for the quantification of 1-hydroxypyrene. The standard curve was linear over the range 10-500 micrograms/L with a correlation coefficient > 0.999. The limit of detection and of quantification were 0.01 ng(signal to noise = 3) and 1.0 microgram/L urine, respectively. The recovery from the entire procedure was found to be 94.0% at 5 micrograms/L and 99.5% at 20 micrograms/L. The intra-day RSD values were found to be 6.2%, and 5.8% at 5, and 20 micrograms/L respectively (all at n = 6). The inter-day RSD values were 7.5%, and 8.9% for 5, and 20 micrograms/L, respectively (all at n = 6). This method is sensitive, efficient and reliable, and was successfully used for the determination of 1-hydroxypyrene in urine of workers exposed to polycyclic aromatic hydrocarbon.

Chromatography, High Pressure Liquid↗
PubMed2003

[Study on the ammonia-oxidizing bacteria from activated sludge samples by the molecular analysis].

The molecular analysis methods of PCR amplification, random cloning and sequencing were used to investigate the ammonia-oxidizing bacterial community composition and the activity of ammonia-monooxygenase (AMO) from the activated sludge samples of an industrial wastewater treatment plant receiving sewage with high ammonia concentration. It is the first time to use PCR-DGGE combined technique to analysis the difference of dominant bacterial community compositions of the activated sludge samples in China. The result showed that the ammonia-oxidizing bacteria (AOB) detected from the activated sludge samples all belong to Nitrosomonas sp. The activity of AMO, the stability of bacteria community composition and the treatment efficiency of the wastewater treatment system were improved evidently, after the activated sludge system was operated for a certain extant. It is suggested that the molecular techniques will contribute to our understanding of the diversity and function of AOB and will benefit to improve the industrial wastewater treatment system.

Ammonia↗
PubMed2002

Recruitment and regulation of phosphatidylinositol phosphate kinase type 1 gamma by the FERM domain of talin.

Membrane phosphoinositides control a variety of cellular processes through the recruitment and/or regulation of cytosolic proteins. One mechanism ensuring spatial specificity in phosphoinositide signalling is the targeting of enzymes that mediate their metabolism to specific subcellular sites. Phosphatidylinositol phosphate kinase type 1 gamma (PtdInsPKI gamma) is a phosphatidylinositol-4-phosphate 5-kinase that is expressed at high levels in brain, and is concentrated at synapses. Here we show that the predominant brain splice variant of PtdInsPKI gamma (PtdInsPKI gamma-90) binds, by means of a short carboxy-terminal peptide, to the FERM domain of talin, and is strongly activated by this interaction. Talin, a principal component of focal adhesion plaques, is also present at synapses. PtdInsPKI gamma-90 is expressed in non-neuronal cells, albeit at much lower levels than in neurons, and is concentrated at focal adhesion plaques, where phosphatidylinositol-4,5-bisphosphate has an important regulatory role. Overexpression of PtdInsPKI gamma-90, or expression of its C-terminal domain, disrupts focal adhesion plaques, probably by local disruption of normal phosphoinositide balance. These findings define an interaction that has a regulatory role in cell adhesion and suggest new similarities between molecular interactions underlying synaptic junctions and general mechanisms of cell adhesion.

3T3 Cells↗
PubMed2002

A mechanism for microtubule depolymerization by KinI kinesins.

Whereas most kinesins motor along microtubules, KinI kinesins are microtubule depolymerizing machines. Surprisingly, we found that a KinI fragment consisting of only the motor core is capable of ATP-dependent depolymerization. The motor binds along microtubules in all nucleotide states, but in the presence of AMPPNP, microtubule depolymerization also occurs. Structural characterization of the products of AMPPNP-induced destabilization revealed a snapshot of the disassembly machine in action as it precisely deformed a tubulin dimer. While conventional kinesins use the energy of ATP binding to execute a "powerstroke," KinIs use it to bend the underlying protofilament. Thus, the relatively small class-specific differences within the KinI motor core modulate a fundamentally conserved mode of interaction with microtubules to produce a unique depolymerizing activity.

Adenosine Triphosphate↗
PubMed2002

The PTH/PTHrP receptor can delay chondrocyte hypertrophy in vivo without activating phospholipase C.

One G protein-coupled receptor (GPCR) can activate more than one G protein, but the physiologic importance of such activation has not been demonstrated in vivo. We have generated mice expressing exclusively a mutant form of the PTH/PTHrP receptor (DSEL) that activates adenylyl cyclase normally but not phospholipase C (PLC). DSEL mutant mice exhibit abnormalities in embryonic endochondral bone development, including delayed ossification and increased chondrocyte proliferation. Analysis of the differentiation of embryonic metatarsals in vitro shows that PTH(1-34) and forskolin inhibit, whereas active phorbol ester stimulates, hypertrophic differentiation. Thus, PLC signaling via the PTH/PTHrP receptor normally slows the proliferation and hastens the differentiation of chondrocytes, actions that oppose the dominant effects of PTH/PTHrP receptors and that involve cAMP-dependent signaling pathways.

Animals↗
PubMed2002

Involvement of ERK, p38 and NF-kappaB signal transduction in regulation of TLR2, TLR4 and TLR9 gene expression induced by lipopolysaccharide in mouse dendritic cells.

Toll-like receptors (TLR) are sentinel receptors capable of recognizing pathogen-associated molecule patterns (PAMP) such as lipopolysaccharide (LPS) and CpG-containing oligonucleotides (CpG ODN). TLR2 and TLR4 are major receptors for Gram-positive and Gram-negative bacterial cell wall components, respectively. TLR9 is necessary for CpG signalling. LPS or CpG ODN can activate immature dendritic cells (DC) and induce DC maturation characterized by production of cytokines, up-regulation of co-stimulatory molecules, and increased ability to activate T cells. However, little is known regarding the regulation of TLR gene expression in mouse DC. In this study, we investigated the regulation of TLR2, TLR4 and TLR9 gene expression by LPS in murine immature DC. TLR2, TLR4 and TLR9 mRNA were up-regulated following LPS stimulation. The up-regulation of TLR9 expression coincided with significantly increased production of tumour necrosis factor-alpha induced by LPS plus CpG ODN. While inhibition of extracellular signal-related kinase and NF-kappaB activation suppressed the up-regulation of the expression of TLR2, TLR4 and TLR9 mRNA, inhibition of p38 kinase prevented the up-regulation of TLR2 and TLR4 mRNA expression but enhanced the up-regulation of TLR9 expression. These results demonstrated that TLR2, TLR4 and TLR9 gene expression was differently regulated by LPS in mouse immature DC. Up-regulation of TLR2, TLR4 and TLR9 expression by LPS might promote the overall responses of DC to bacteria and help to explain the synergy between LPS and other bacterial products in the induction of cytokine production.

Animals↗
PubMed2002

Cyclic adenosine monophosphate/protein kinase A mediates parathyroid hormone/parathyroid hormone-related protein receptor regulation of osteoclastogenesis and expression of RANKL and osteoprotegerin mRNAs by marrow stromal cells.

Parathyroid hormone (PTH) is a major regulator of osteoclast formation and activation, effects that are associated with reciprocal up- and down-regulation of RANKL and osteoprotegerin (OPG), respectively. The roles of specific downstream signals generated by the activated PTH/PTH-related protein (PTHrP) receptor (PTH1R), such as cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) and phospholipase C/protein kinase C (PLC/PKC), in controlling RANKL and OPG expression and osteoclastogenesis remain uncertain. In MS1 conditionally transformed clonal murine marrow stromal cells, which support PTH-induced osteoclast formation from cocultured normal spleen cells, PTH(1-34) increased RANKL and macrophage colony-stimulating factor (M-CSF) mRNA expression and decreased that of OPG when present continuously for 7-20 days at 37 degrees C in the presence of dexamethasone (Dex). In cells precultured for 7 days and then treated with PTH(1-34), similar reciprocal regulation of RANKL and OPG occurred, maximally at 6-24 h, that was of greater amplitude than the changes induced by chronic (7-10 days) PTH exposure. These acute effects of PTH(1-34) were mimicked by PKA stimulators (8-bromoadenosine [8Br]-cAMP or forskolin [FSK]), blocked by the PKA inhibitor Rp-cAMPs but unaffected by the PKC inhibitor GF109203X. Amino-truncated PTH(1-34) analogs PTH(5-34) and PTH(7-34) neither increased cAMP production in MS1 cells nor regulated RANKL or OPG mRNA. Reciprocal RANKL/OPG mRNA regulation was induced in MS1 cells by PTH(3-34) but only at high concentrations that also increased cAMP. The highly PKA-selective PTH analog [Gly1,Arg19]human PTH(1-28) exerted effects similar to PTH(1-34) on RANKL and OPG mRNAs and on osteoclast formation, both in MS1/spleen cell cocultures and in normal murine bone marrow cultures. The direct PKC stimulator 12-O-tetradecanoylphorbol-13-acetate (PMA) did not induce RANKL mRNA in MS1 cells, but it did up-regulate OPG mRNA and also antagonized osteoclast formation induced by PTH(1-34) in both MS1/spleen cocultures and normal bone marrow cultures. Thus, cAMP/PKA signaling via the PTH1R is the primary mechanism for controlling RANKL-dependent osteoclastogenesis, although direct PKC activation may negatively regulate this effect of PTH by inducing expression of OPG.

Animals↗
PubMed2002

Study on the correlation between tongue size and openbite.

OBJECTIVE: To investigate the correlation between tongue size and openbite. METHODS: The tongue size of the openbite patients and the subjects with normal occlusion was measured by B-type ultrasonic imaging respectively. The tongue size of the openbite patients and the subjects with normal occlusion was compared. RESULTS: The tongue size in openbite group was larger than in normal occlusion group. The difference was statistically significant. CONCLUSIONS: Tongue size was related to the openbite.

Adolescent↗
PubMed2002

[The observation of chronic prostatis patients using the National Institutes of Health Chronic Prostatitis Symptom Index].

OBJECTIVES: The National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) was used to determine the chronic prostatitis syndrome in young men (from 20 to 48 years old) of clinical validity. METHODS: 227 patients with chronic prostatitis syndrome (CPS)/chronic pelvic pain syndrome and 32 patients with BPH were randomized to study using NIH-CPSI. RESULTS: 1. The main manifestations of CPS patients were pain or uncomfort. Those were more common in CPS than BPH. 2. 79.30% CPS patients had a sensation of not emptying bladder completely after finished urinating, 44.93% patients had to urinate again less than two hours after finished urinating. 3. 51.51% patients with CPS have more effect on work, 90.31% patients on free life, and 68.72% patients on quality of life than BPH. CONCLUSIONS: According NIH-CPSI, the main manifestations of CPS are pain or uncomfort. CPS patients have more effect on work and quality of life.

Adult↗
PubMed2002

[The treatment of method of regulating qi by alleviation of mental depress in chronic abacteria prostatitis].

OBJECTIVES: To evaluate the efficacy of method of regulating qi by alleviation of mental depress for chronic abacteria prostatitis (CAP). METHODS: From Aug. 2000 to Dec. 2000, 60 patients underwent TCM treatment with either method of regulating qi by alleviation of mental depress (31 cases) or promoting blood circulation (29 cases). RESULTS: The marked rate and effective rate were 83.86%, 93.55% in treatment group, and 65.52%, 93.10% in the control group, respectively. The marked rate in treatment group was higher than that of control group. Scores of NIH-CPSI were more decreased in treatment group than that in control group(P < 0.05). The quality of life improved significantly in treatment group than that in control group (P < 0.05). CONCLUSIONS: Method of regulating qi by alleviation of mental depress had its advantage over methods of promoting blood circulation for CAP and was an effective treatment modality for CAP.

Adult↗
PubMed1998

Syntheses and Characterizations of a Series of Tetradecanuclear Molybdenum(Tungsten)/Copper/Sulfur Heterobimetallic Cluster Compounds.

Using sulfide ion to substitute the weakly copper(I)-philic ligands of MS(4)(-)(n)()(2)(-)O(n)()/Cu(+) compounds, (M = Mo, W; n = 0, 1), we have prepared and characterized four novel tetradecanuclear clusters having the general formula [(n-Bu)(4)N](4)[M(4)Cu(10)S(16)E(2)E']H(2)O, (M = Mo, E = E' = O for complex 1; M = W, E = (1)/(2)O + (1)/(2)S, E' = O, for complex 2; M = Mo, E = S, E' = (1)/(2)O + (1)/(2)S for complex 3; M = W, E = E' = S, for complex 4). Crystal structures of compounds 1-4 were determined; they are isomorphous and crystallized in the orthorhombic space group Pna2(1), with a = 26.6997(2) Å, b = 19.3133(4) Å, c = 21.4577(4) Å, V = 11064.9(3) Å(3), Z = 4 for [(n-Bu)(4)N](4)[Mo(4)Cu(10)S(18)O].H(2)O (3) and with a = 26.8141(8) Å, b = 19.4412(6) Å, c = 21.4039(5) Å, V = 11157.8(5) Å(3), Z = 4 for [(n-Bu)(4)N](4)[W(4)Cu(10)S(19)].H(2)O (4). The cluster cores have approximate sigma symmetry. The anions 1-4 may be viewed as consisting of one incomplete cubane-like Cu(3)MS(3)E fragment, one trigonal prism-type Cu(3)MS(4), and two butterfly-type Cu(2)MS(3)E' fragments, bridged by two &mgr;(3)-S and one &mgr;(4)-S atoms. There are two (&mgr;(3)-S)Cu(3) configurations in the compounds. Infrared, Raman, and UV/vis spectra of the above compounds are discussed, and the main absorption bands are assigned. (95)Mo NMR spectra and cylic voltammograms are investigated and compared with those of other compounds, (95)Mo NMR spectra show that in the solution there are three kinds of coordination environments of Mo in complexes 1 and 3, and cyclic voltammograms indicate that complexes 1-4 have irreversible electrochemical reductions.

Journal Article↗