Biomedical subjects

Jun Guo

Publications and source records attributed to Jun Guo.

At least 55 records · Page 3Linked to original sources

PubMed2005

[Safety destruction of tetramethylene disulfotetramine and its medical waste].

OBJECTIVE: To develop suitable methods for safety destruction of tetramethylene disulfotetramine (TETS) and the medical wastes polluted by TETS. METHODS: The chemical stability of TETS was evaluated under the conditions of acid, alkali and high temperature. TETS was treated with sodium hydroxide, hydrochloric acid, sulfuric acid and nitric acid under various treatment conditions, i.e. concentration, temperature and time, followed by determining remaining TETS using gas chromatograms to estimating the degradation efficiency of TETS. TETS was put into ampoule and heated under the different conditions of temperature and time. After heat treatment, TETS residue was determined. For evaluating the absorption factor of active carbon to TETS in water and blood, active carbon was added into the water and blood with content of TETS, incubated at room temperature for 24 hours, and then determined the remaining TETS in water and blood. RESULTS: The complete degradation of TETS was achieved by one of the following treatments: heating with 6.0 mol/L hydrochloric acid at 100 degrees C for half an hour, heating with 3.0 mol/L hydrochloric acid or 6.0 mol/L sodium hydroxide at 100 degrees C for 3 hours, mixing with concentrated sulfuric acid or nitric acid at room temperature for 24 hours, and dry heating at 300 degrees C for 4.5 hours. Active carbon showed a marked effectiveness in absorbing the TETS in blood and water, with the mean absorption efficiency of over 90%. CONCLUSIONS: The results of this study suggest that TETS powder should be degraded by acid or alkali, and that the solid medical wastes polluted by TETS should be destroyed at high temperature. For the blood and water having contents of TETS, the active carbon should be used as to absorbing the TETS and then be destroyed at high temperature.

Bridged-Ring Compounds↗

PubMed2005

[Factors associated with acute ST-segment elevation myocardial infarction with normal angiographic findings of the coronary artery].

OBJECTIVE: To identify the factors related to acute ST-segment elevation myocardial infarction (STEMI) with normal angiographic findings of the coronary artery. METHODS: An retrospective analysis of the electrocardiographic, echocardiographic, and angiographic data of 271 STEMI cases was conducted. Of these patients, 29 had normal coronary artery by angiography and from the rest patients presenting abnormal angiographic findings of the coronary artery, 60 were randomly selected to serve as the control group. Multiple logistic regression analysis was performed to identify the independent factors related to acute STEMI with normal coronary artery by angiography. RESULTS: The incidence rate of STEMI with normal coronary artery was 10.7%. Univariate analysis showed that age, smoking, diabetes mellitus, absence of pre-infarction angina, and wall motion score were related to STEMI with normal coronary artery (P<0.05), whereas multiple logistic regression analysis identified the former 3 factors as the related factors (P<0.05). Wall motion score, left ventricular ejection fraction, cardiac index, and stroke volume index were higher, and cardiac events fewer in patients with normal coronary artery than in those with abnormal coronary artery (P<0.01). CONCLUSION: Acute STEMI with normal coronary artery is more likely to occur in young smokers without pre-infarction angina, possibly in association with spontaneous reperfusion.

Adult↗

PubMed2005

[Analysis of different reperfusion methods for acute ST segment elevation myocardial infarction].

OBJECTIVE: To evaluate significance of different reperfusion methods in the treatment of acute ST segment elevation myocardial infarction (STEMI). METHODS: A retrospective analysis of the clinical data of electrocardiography (ECG), echocardiogram, and angiography was conducted in 271 cases of STEMI treated in our hospital. Of these patients 31 were treated by primary percutaneous coronary intervention (PCI), and 44 by intravenous thrombolysis with urokinase, including 26 with thrombolytic treatment with concomitant PCI and 18 with rescue PCI. RESULTS: The patients receiving primary PCI, thrombolytic therapy along with PCI, and rescue PCI did not exhibit significant differences in age, sex, diabetes, hypertension, hyperlipidemia, smoking status, symptom onset to treatment time, or collateral circulation (P>0.05). The incidence of cardiac events including unstable angina, complex ventricular arrhythmia, and cardiac insufficiency were not significantly different between the 3 groups (P>0.05), nor was Killip class, number of Q waves on ECG, wall motion score, left ventricular ejection fraction, cardiac index, or stroke volume index (P>0.05). CONCLUSION: Combination of thrombolytic therapy and interventional therapy can be a safe and effective treatment of STEMI, and rescue PCI may benefit the improvement of the left ventricular function.

Angioplasty, Balloon, Coronary↗

PubMed2005

[Analysis of misdiagnosis in 33 cases of aortic dissection].

OBJECTIVE: To compare the clinical characteristics, clinical course and laboratory findings of diagnosed and misdiagnosed cases of aortic dissection (AD). METHODS: The data of 33 cases of AD were collected for a retrospective review. All the patients underwent examination with X-ray and B-type ultrasound, and diagnosis of the suspected cases was further verified CT and magnetic resonance imaging according to the criteria of presence of false lumen or free valves. Diagnosis of AD was established in 18 of the 33 patients, including 14 male and 4 female patients aged from 20 to 79 years with a mean of 55.8+/-11.4 years. Misdiagnosis occurred in 15 patients including 12 male and 3 female patients aged 22-75 years with a mean of 56.2+/-10.8 years. RESULTS: No significant differences were found between the diagnosed and misdiagnosed groups in terms of age, sex, hypertension, coronary heart disease, chest pain, heart murmur, pericardial effusion, pleural effusion, average systolic and diastolic pressure, white blood cell count, creatine phosphokinase (CK) and its isoenzyme CK-MB, or De Bakey type III (P>0.05). Significant differences in peripheral large blood vessel murmur, asymmetric blood pressure of the arm and leg, ST segment variation, arrhythmia, and De Bakey types I and II were noted between the two groups (P<0.05). In cases misdiagnosed as acute coronary syndrome, ST segment variation, creatine kinase, arrhythmia, and white blood cell count were significantly different from those in cases of diagnosed as AD (P<0.01), but CPK-MB and cardiac troponin I were comparable. CONCLUSION: The initial symptoms, disease course, cardioelectrographic changes and creatine kinase of AD can be easily confused with those of acute coronary syndrome, and special attention should be given to their differentiation.

Adult↗

PubMed2005

[Bacterial Fe(III) reduction].

Bacterial Fe(III) reduction is an important pathway of bioenergy metabolism in the process of life evolution. Many kinds of archaebacteria and eubacteria are capable of reducing Fe(III) to conserve energy. Anaerobic Fe(III) respiration pathway involves many membranous proteins and regulating factors, especially the muti-haem c-type cytochromes are very important in the course of electron transportation. In addition, bacterial Fe(III) reduction play important roles in the biological geochemistry circulation and environmental remediation, therefore has vital environmental significance.

Bacteria↗

PubMed2005

[Comparison on energy values of matching food items in food compositon table of four northeast Asian countries or region].

OBJECTIVE: To evaluate the consistency and compatibility of the energy values in present applied Food Composition Tables or Databases (FCTs or FCDs) of NeasiaFoods members. METHODS: A total 101 matching food items (N = 101 x 4) were selected from the FCTs or FCD of Japan, Korea, Taiwan and China. Statistical comparisons were conducted before and after water adjustment. Data profile plots, means and relative differences were provided. The significance of differences were examined by the block designed ANOVA (alpha = 0.05). RESULTS: The population mean of Chinese food items is significantly low than that of other three. Relative difference (mean and 95% CI) of water adjusted estimation indicate that energy of China is totally less 7.7% (-0.6% - 15.9%), 11.7% (3.5 % - 20.1 %) and 2.6% (-5.2% - 10.3%) than that of Japan, Taiwan, and Korea respectively. Major bias occurred in Nuts & seeds and Fungi & Algae, Japan and Taiwan higher 22% to 68% than China. CONCLUSIONS: The energy values in FCTs of these NEASIAFOODS members lack consistency, especially between China and other three members. Differences of food energy conversion systems are the main effect that producing discrepancies. The effect of bias in energy contributing nutrients (e.g. fat) are considerable; analytical errors, sampling errors, food processing effects, different of food species, and accumulation of them only can be estimated through interlaboratory comparison studies on the basis of totally same food samples.

Asia↗

PubMed2004

Splenic stroma drives mature dendritic cells to differentiate into regulatory dendritic cells.

The fates of dendritic cells (DCs) after antigen presentation have been studied extensively, but the influence of lymphoid microenvironments on DCs is mostly unknown. Here, using splenic stromal cells to mimic the immune microenvironment, we show that contact with stromal cells promoted mature DCs to proliferate in a fibronectin-dependent way and that both stromal cell contact and stromal cell-derived transforming growth factor-beta induced their differentiation into a new regulatory DC subset. We have identified an in vivo counterpart in the spleen with similar phenotype and functions. These differentiated DCs secreted nitric oxide, which mediated the suppression of T cell proliferation in response to antigen presentation by mature DCs. Thus, our findings identify an important mechanism by which the microenvironment regulates immune responses.

Animals↗

PubMed2004

BetaIVSigma1 spectrin stabilizes the nodes of Ranvier and axon initial segments.

Saltatory electric conduction requires clustered voltage-gated sodium channels (VGSCs) at axon initial segments (AIS) and nodes of Ranvier (NR). A dense membrane undercoat is present at these sites, which is thought to be key for the focal accumulation of channels. Here, we prove that betaIVSigma1 spectrin, the only betaIV spectrin with an actin-binding domain, is an essential component of this coat. Specifically, betaIVSigma1 coexists with betaIVSigma6 at both AIS and NR, being the predominant spectrin at AIS. Removal of betaIVSigma1 alone causes the disappearance of the nodal coat, an increased diameter of the NR, and the presence of dilations filled with organelles. Moreover, in myelinated cochlear afferent fibers, VGSC and ankyrin G clusters appear fragmented. These ultrastructural changes can explain the motor and auditory neuropathies present in betaIVSigma1 -/- mice and point to the betaIVSigma1 spectrin isoform as a master-stabilizing factor of AIS/NR membranes.

Animals↗

PubMed2004

Fluorescence assay of SIRT protein deacetylases using an acetylated peptide substrate and a secondary trypsin reaction.

A novel fluorescent substrate was devised for the sirtuin (SIRT) class of human protein deacetylases comprised of a peptide sequence containing a single acetyl-lysine residue, with a fluorescent group (tetramethylrhodamine-6-carboxylic acid, 6-TAMRA) near the carboxyl terminus and a nonfluorescent quenching group (QSY-7) near the amino terminus. The peptide sequence is modeled after the p53 acetylation site but is unreactive toward trypsin because all other lysine and arginine residues have been replaced by serine. However, the SIRT-deacetylated peptide is readily cleaved by trypsin, resulting in a maximal 30-fold enhancement of the 6-TAMRA fluorescence. Nicotinamide at millimolar concentrations stops the deacetylation but does not inhibit trypsin, and a microtiter plate assay of the SIRTs has been devised using the fluorescent substrate and these reagents. Using this method, the kinetics of the reaction of the cosubstrate nicotinamide adenine dinucleotide and the competitive inhibitor nicotinamide with SIRT1 and SIRT2 has been analyzed. Several nicotinamide analogs have also been tested as inhibitors and found to have much lower affinity for these enzymes than does the parent compound.

Chromatography, High Pressure Liquid↗

PubMed2004

A simple solid phase diversity linker strategy using enol phosphonates.

Polymer bound lactam enol phosphonates can be easily generated using simple phenol on polystyrene resin. These stable, storable compounds can be released in a diversity cleavage strategy, using Suzuki cross coupling conditions, to provide 2-arylenamides in moderate to good overall yields.

Cross-Linking Reagents↗

PubMed2004

Enhanced chemosensitivity to irinotecan by RNA interference-mediated down-regulation of the nuclear factor-kappaB p65 subunit.

In preclinical tumor models, inhibition of nuclear factor-kappaB (NF-kappaB) has been associated with increased sensitivity to chemotherapeutic agents such as irinotecan (CPT-11). This is based on the fact that a variety of chemotherapy agents such as CPT-11 activate NF-kappaB to result in the expression of genes such as c-IAP1 and c-IAP2 that might be responsible for the inhibition of chemotherapy-induced apoptosis. In this study, RNA interference [small interfering RNA (siRNA)] was used to down-regulate the NF-kappaB p65 subunit in the HCT116 colon cancer cell line, and its role, in the presence and absence of CPT-11, was assessed on cell growth and apoptosis. Reduction of endogenous p65 by siRNA treatment significantly impaired CPT-11-mediated NF-kappaB activation, enhanced apoptosis, and reduced colony formation in soft agar. Furthermore, the in vivo administration of p65 siRNA reduced HCT116 tumor formation in xenograft models in the presence but not the absence of CPT-11 administration. These data indicate that the administration of siRNA directed against the p65 subunit of NF-kappaB can effectively enhance in vitro and in vivo sensitivity to chemotherapeutic agents.

Agar↗

PubMed2004

N-methyl-D-aspartate receptor and L-type voltage-gated Ca2+ channel activation mediate proline-rich tyrosine kinase 2 phosphorylation during cerebral ischemia in rats.

Cerebral ischemia induces rapid efflux of glutamate into the extracellular space contributing to excessive activation of glutamate receptors in postsynaptic cells, particularly N-methyl-D-aspartate (NMDA) receptors, which triggers the neuron lesion through calcium overload. Our studies indicated that cerebral ischemia stimulated the rapid activation of nonreceptor tyrosine kinases proline-rich tyrosine kinase 2 (Pyk2) and Src and the binding to Pyk2 activated the latter. Pyk2 activation significantly depends on the increase of the intracellular calcium level; blockage of both calcium ion channel NMDA receptors and L-type voltage-gated Ca2+ channel (L-VGCC), respectively, could effectively inhibit phosphorylation of Pyk2 in early ischemia episodes. Moreover, pretreatment with the protein kinase C inhibitor (chelerythrine chloride) reduced the ischemia-induced activation of Pyk2. Noticeably, CaMKII, a family of calcium/calmodulin-dependent kinases, also may be involved in the regulation of Pyk2 activity because its inhibitor KN62 attenuated Pyk2 phosphorylation during ischemia. Together with previous studies, these results indicate that calcium influx elicited by active NMDA receptors and L-VGCC triggers the Pyk2-Src signaling pathway mediated by PKC, which aggravates cerebral ischemia lesions through up-regulating the function of NMDA receptors after the onset of ischemia, and also could be regulated partly by CaM-dependent kinases like CaMKII.

Animals↗

PubMed2004

A minimal length between tau exon 10 and 11 is required for correct splicing of exon 10.

Mutations that stimulate exon 10 inclusion into the human tau mRNA cause frontotemporal dementia with parkinsonism, associated with chromosome 17 (FTDP-17), and other tauopathies. This suggests that the ratio of exon 10 inclusion to exclusion in adult brain is one of the factors to determine biological functions of the tau protein. To investigate the underlying splicing mechanism and identify potential therapeutic targets for tauopathies, we generated a series of mini-gene constructs with intron deletions from the full length of tau exons 9-11 mini-gene construct. RT-PCR results demonstrate that there is a minimum distance requirement between exon 10 and 11 for correct splicing of the exon 10. In addition, SRp20, a member of serine-arginine (SR) protein family of splicing factors was found to facilitate exclusion of exon 10 in a dosage-dependent manner. Significantly, SRp20 also induced exon 10 skipping from pre-mRNAs containing mutations identified in FTDP-17 patients. Based on those results, we generated a cell-based system to measure inclusion to exclusion of exon 10 in the tau mRNA using the luciferase reporter. The firefly luciferase was fused into exon 11 in frame, and a stop code was also created in exon 10. Inclusion of exon 10 prevents luciferase expression, whereas exclusion of exon 10 generates luciferase activity. To minimize baseline luciferase expression, our reporter construct also contains a FTDP-17 mutation that increases exon 10 inclusion. We demonstrate that the splicing pattern of our reporter construct mimics that of endogenous tau gene. Co-transfection of SRp20 and SRp55, two SR proteins that promote exon 10 exclusion, increases production of luciferase. We conclude that this cell-based system can be used to identify biological substances that modulate exon 10 splicing.

Alternative Splicing↗

PubMed2004

Angiotensin II stimulates Pax-2 in rat kidney proximal tubular cells: impact on proliferation and apoptosis.

BACKGROUND: The intrarenal renin-angiotensin system (RAS) is intimately involved in the tubular cell proliferation, apoptosis and regeneration that occur following renal injury. Though tubular angiotensin II (Ang II) type 2 receptors (AT2R) decrease greatly after birth, their number increases after injury. Notably, during recovery from injury, renal tubular cells display a relatively immature phenotype expressing genes that are involved in nephron development, for example, the paired homeobox-2 gene (Pax-2). The present investigation hypothesized that AT2R activation would stimulate Pax-2 gene expression in immortalized rat renal proximal tubular cells (IRPTC), as we have found in fetal cells. METHODS: Pax-2 gene expression in IRPTC was evaluated by immunofluorescence, Western blot, reverse transcription-polymerase chain reaction (RT-PCR) with or without Ang II treatment; apoptosis and proliferation were analyzed by terminal transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL) assay and bromodeoxyuridine (BrdU) incorporation in stable IRPTC transformants with Pax-2 sense and antisense orientation, respectively. RESULTS: Ang II up-regulated Pax-2 gene expression via AT2R in IRPTC. The stimulatory effect of both Ang II on Pax-2 gene expression was blocked by PD123319 (AT2R inhibitor), AG 490 (specific Janus kinase 2 (JAK2) inhibitor) and genistein (tyrosine kinase inhibitor), but not by losartan (AT1R inhibitor). Stable transfection of sense Pax-2 cDNA increased, whereas antisense Pax-2 cDNA down-regulated Pax-2 expression. CONCLUSION: Our studies suggest that Ang II stimulates Pax-2 gene expression in IRPTC via AT2R and the JAK2/signal transducers and activators of transcription (STAT) signaling transduction pathway, which may be important in renal repair following injury. Cells lacking Pax-2 gene expression appear to be prone toward apoptosis rather than proliferation.

Angiotensin II↗

PubMed2004

The cyclin-dependent kinase inhibitor p57(Kip2) mediates proliferative actions of PTHrP in chondrocytes.

Parathyroid hormone-related peptide (PTHrP) is a positive regulator of chondrocyte proliferation during bone development. In embryonic mice lacking PTHrP, chondrocytes stop proliferating prematurely, with accelerated differentiation. Because the bone phenotype of mice lacking the cyclin-dependent kinase inhibitor p57(Kip2) is the opposite of the PTHrP-null phenotype, we hypothesized that PTHrP's proliferative actions in chondrocytes might be mediated by opposing p57. We generated p57/PTHrP-null embryos, which showed partial rescue of the PTHrP-null phenotype. There was reversal of the loss of proliferative chondrocytes in most bones, with reversal of the accelerated differentiation that occurs in the PTHrP-null phenotype. p57 mRNA and protein were upregulated in proliferative chondrocytes in the absence of PTHrP. Metatarsal culture studies confirmed the action of PTHrP to decrease p57 mRNA and protein levels in a model in which parathyroid hormone (PTH), used as an analog of PTHrP, increased chondrocyte proliferation rate and the length of the proliferative domain. PTH treatment of p57-null metatarsals had no effect on proliferation rate in round proliferative chondrocytes but still stimulated proliferation in columnar chondrocytes. These studies suggest that the effects of PTHrP on both the rate and extent of chondrocyte proliferation are mediated, at least in part, through suppression of p57 expression.

Animals↗

PubMed2004

Competitive binding of postsynaptic density 95 and Ca2+-calmodulin dependent protein kinase II to N-methyl-D-aspartate receptor subunit 2B in rat brain.

AIM: To investigate the interactions among postsynaptic density 95 (PSD-95), Ca2+-calmodulin dependent protein kinase IIalpha (CaMKIIalpha), and N-methyl-D-aspartate receptor subunit 2B (NR2B) during ischemia and reperfusion in hippocampus of rats. METHODS: Brain ischemia was induced by four-vessel occlusion procedure in rats. Immunoprecipitation and immunoblotting were performed to study the interactions and phosphorylation of proteins. The association-dissociation of PSD-95 and CaMKIIalpha to and from N-methyl-D-aspartate (NMDA) receptor induced by ischemia and reperfusion and the effects of 1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenyl-piperazine (KN-62, a selective inhibitor of CaMKII) on these protein interactions were investigated. Coimmunoprecipitation and immunoblotting were performed for the studies of interactions among proteins. RESULTS: The alternations of the binding level of PSD-95 and CaMKIIalpha to NR2B during ischemia and reperfusion demonstrated the negative correlation to each other. Pre-administration of KN62 through both cerebral ventricles inhibited the 10 min ischemia-induced increase of the binding of PSD-95 to NR2B and, on the contrary, promoted the binding of CaMKIIalpha to NR2B. CONCLUSION: PSD-95 competes with CaMKII to bind to NR2B during ischemia and reperfusion in rat hippocampus.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2004

[Urodynamic analysis of urinary incontinence after transurethral resection of prostate].

OBJECTIVE: To investigate the value of urodynamic test in the diagnosis of postoperative incontinence after transurethral resection of the prostate(TURP). METHODS: Thirty-seven patients with urinary incontinence after TURP received urodynamic tests, including cystometry(CMG), pressure-flow study, rest urethral pressure profilometry(RUPP) and stress leak-point pressure (SLPP) measurement. Urethrocystography was taken when necessary. RESULTS: Of the 37 cases, 16 were diagnosed as motor urge urinary incontinence, 2 as sensory urge urinary incontinence, 17 as stress urinary incontinence and 2 as overflow urinary incontinence. CONCLUSION: Different types of urinary incontinence after TURP can be clearly distinguished by urodynamic tests, which provides objective basis for the choice of adequate treatment.

Aged↗

PubMed2004

[Topic selection and design for andrological researches in Chinese traditional medicine].

The past decade was witnessed a rapid development of andrology in Chinese Traditional Medicine (ACTM) and a steady growth of the contingent of clinicians and researchers in this domain. Now we are challenged to a very important task of how to raise the clinical and research levels to a new height. Topic selection in the researches on ACTM showed be accurate, scientific and practical, and the research design should follow the principles of multi-centering, randomization, controlling and blind trials. This article also discusses the characteristics and evaluation of the researches on ACTM.

Andrology↗