Biomedical subjects

J Guo

Publications and source records attributed to J Guo.

At least 109 records · Page 6Linked to original sources

PubMed2001

[Compounds from roots of Chirita fimbrisepala Hand.-Mazz].

OBJECTIVE: To study the chemical constituents the roots of Chirita fimbrisepala. METHOD: The constituents were extracted with solvent, separated and purified with chromatographic methods, identified by NMR, MS, UV, IR and physical-chemical constants. RESULT: Three flavonoids mahuangchiside(I), hispidulin (II) and kaempferol(III) were isolated with daucosteral(IV). CONCLUSION: I is a new compound elucidated as hispidulin-7-O-beta-D-xylopyranosyl-(1-->2)-beta-D-xylopyranoside, named mahuangchiside, II and III were isolated for the first time from the family Gesneriaceae, and IV was isolated for the first time from the genus Chirita.

Disaccharides↗

PubMed2001

[A-ring formylated flavonoids and oxoaporphinoid alkaloid from Dasymaschalon rostratum Merr. et Chun].

OBJECTIVE: To study the chemical components in the stem of Dasymaschalon rostratum. METHOD: The components were extracted with solvent, separated and purified with chromatographic methods, identified by NMR, MS, UV, IR and physicol-chemical constants. RESULTS: Three A-ring-formylated flavonoids and one oxoaporphinnoid aikaloid were isolated and identified as lawinal, unonal, isounonal and 7-oxodehydroasimilobine. CONCLUSION: All the four compounds were isolated for the first time from the genus Dasymaschalon. According to all the phytochemistry papers on Annonaceae, A-ring formylated flavonoids in this family were isolated from the genus Desmos for the first time. Thus, it is an interesting discovery in chemotaxonomy which reveals the close relationship between the two genera Desmos and Dasymaschalon.

Annonaceae↗

PubMed2001

[An experimental study on the blood vessel sclerosing therapeutic agents for cavernous hemangiomas].

OBJECTIVE: This study was designed to test what are the suitable drugs for sclerotherapy and investigate the formation mechanism of cavernous hemangiomas. METHODS: A total of 84 rabbits were selected for this study, and divided into 6 groups, including one control group and five experimental groups. We selected auricular veins of rabbits as the location of injection. The rabbits of the control were injected with physiological saline, and the rabbits of the experimental groups were injected respectively with various drugs, including 5% sodium morrhuate, 10% alum, pinyungmycin, leurocristine and the combination of pinyungmycin and dexamethasone. Histopathological changes were analyzed after 3, 7, 14, 21, 28, 35 days of sclerotherapy. RESULTS: According to histopathological changes of tissue, 5% sodium morrhuate, 10% alum, and the combination of pinyungmycin and dexamethasone produced better eutherapeutic effects, when comparing with other methods. However, 5% sodium morrhuate caused tissue necrosis of the injection site. CONCLUSION: The combined therapy of pinyungmycin and dexamethasone produced excellent sclerotic effects. Whatever drugs causing serious damage of HVEC may contribute to the therapy for cavernous hemangiomas.

Animals↗

PubMed2001

[Expression and significance of TGF-beta 1 in nasal polyps].

OBJECTIVE: To study the expression and significance of transforming growth factor-beta 1(TGF-beta 1) in nasal polyps. METHOD: Expression of TGF-beta 1 in nasal polyps from 34 patients and middle turbinates from 30 patients with deviation of nasal septum were prospectively studied with immunohistochemistry. Each tissue section was observed under optical microscope. RESULT: 1. The TGF-beta 1 positivity in extracellular matrix and in cells in the stroma was significantly higher in nasal polyps than in middle turbinates (P < 0.01). 2. The distribution and shape of TGF-beta 1 expressing cells in nasal polyps was similar to that of eosinophil, their positivities were significantly correlative (P < 0.05). 3. The positivity of TGF-beta 1 did not correlate with clinical type of nasal polyps (P > 0.05), eosinophil infiltration correlated significantly with clinical type of nasal polyps(P < 0.05). CONCLUSION: 1. The TGF-beta 1 may contribute to some of the pathologic changes observed in nasal polyps, such as thickening of the epithelial basement membrane and stromal fibrosis. 2. Eosinophils in nasal polyps represent a major source of TGF-beta 1. 3. Eosinophils infiltration may play a prominent role in the development and recurrence of nasal polyps.

Adolescent↗

PubMed2001

[Effect of multi-micronutrient on heat adaptation and its probable mechanism].

A multi-micronutrient compound is composed of ascorbic acid, thiamin, riboflavin, vitamin B6, niacin, folic acid, K, Na, Ca, Mg, Cu, Mn, Fe and Zn. In order to explore the effect of the multi-micronutrient on heat adaptation and its probable mechanism, heat-exposed Drosophila melanogaster, mice and rats were observed. The results showed that the multi-micronutrient could significantly increase the survival rate of heat-exposed Drosophila melanogaster and prolong the survival time and swimming time of mice under high temperature. The results indicated that the significant influence of multi-micronutrients on heat adaptation could be the result of enhancing the glucocorticoid receptor activity in hepatic cytosol in the heat-exposed rats, inhibiting liver phospholipase A2 activity in the heat-exposed rats, increasing serum SOD activity and decreasing serum MAD content in the heat-exposed rats, as well as increasing level of HSP70 in the heat-exposed Drosophila melanogaster. The results suggested that the effect of enhancing heat adaptation might be related to improving neuroendocrine regulation, enhancing anti-oxidative function against the damage of free radicals as well as increasing HSP70 content.

Adaptation, Physiological↗

PubMed2001

[Response property of tone burst transmission of partially implantable middle ear implant in vivo].

OBJECTIVE: To investigate the characteristics of tone burst transmission of the middle ear implant(MEI). METHODS: Ten adult rabbits with normal hearing were used. A silver ball electrode was placed at the round window membrane to measure cochlear microphonics (CM) when sounds were presented before and after the implantation of the MEI. The tone burst was the acoustic stimulus. RESULTS: Frequency response functions without and with the MEI in rabbit model were calculated, and their amplitude-frequency curves ranging from 0.5 to 6 kHz resembled each other in shape with gain factors about 15 dB at the frequencies above 1 kHz. CONCLUSION: The results of this study indicated that the frequency response of the device fitted the speech transmission and it had high fidelity with little noise.

Animals↗

PubMed2001

[Roles of CD43, CD20 and local IgE in the pathogenesis of nasal polyps].

OBJECTIVE: To estimate the roles of CD43, CD20 and total IgE in the pathogenesis of nasal polyps. METHOD: Twenty-six cases of nasal polyps and 20 cases of mucosa of middle turbinates were used in present study. RESULTS: The number of CD43+ cells, CD20+ cells and plasma cells in nasal polyps were significantly more than that in middle turbinates (P < 0.01). The positive rate of local IgE+ cells in nasal polyps was significantly higher than in middle turbinate (P < 0.01). CONCLUSION: There were active cellular immunity and humoral immunity in nasal polyps. Local allergy may play a role in the pathogenesis of nasal polyps.

Adolescent↗

PubMed2001

[Expression of vascular endothelial growth factor and transforming growth factor-beta 1 in nasal polyps].

OBJECTIVE: To study the expression and significance of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) and transforming growth factor-beta 1(TGF-beta 1) in nasal polyps. METHODS: Expression of VEGF/VPF and TGF-beta 1 in nasal polyps from 34 patients and middle turbinates from 30 patients with deviation of nasal septum was prospectively studied with immunohistochemistry. Tissue sections were observed under optical microscope. RESULTS: (1) The VEGF/VPF positivity in vascular endothelium and in glandular cell was significantly higher in nasal polyps than in middle turbinates (P < 0.01 and P < 0.05, respectively); (2) The TGF-beta 1 positivity in extracellular matrix and in cells in the stroma was significantly higher in nasal polyps than in middle turbinates(P < 0.005); (3) The distribution and shape of TGF-beta 1 expressing cells in nasal polyps were similar to that of eosinophil, their positivities were significantly correlative; (4) The positivity of VEGF/VPF and TGF-beta 1 did not correlate with clinical type in nasal polyps (P > 0.05). CONCLUSION: (1) The VEGF/VPF may play a key role in the formation of heavy edema of nasal polyps; (2) The TGF-beta 1 may contribute to some of the pathologic changes observed in nasal polyps, such as thickening of the epithelial basement membrane and stromal fibrosis; (3) Eosinophils in nasal polyps represent a major source of TGF-beta 1.

Adolescent↗

PubMed2001

Comparative experimental study of Ho-Yag laser and true-cut biopsy needle in myocardial revascularization.

OBJECTIVE: To study the mechanism and effects of blood perfusion on acute ischemic region of myocardium through channel created by Ho-Yag laser and True-cut biopsy needles with myocardial contrast echocardiography. METHODS: We partially ligated the left anterior descending coronary artery of canine hearts between the 1st and 2nd diagonal branches to produce two groups of acute myocardial ischemia models and then performed transmyocardial revascularization (TMR) on this region with Ho-Yag laser and True-cut biopsy needles. Myocardial contrast echocardiography was performed with a new generation of ultrasound contrast agent and second harmonic imaging of this region before, during ischemia and after revascularization. Pictures were taken with "R" wave trigger skill. RESULTS: Acoustic density (dB) in the ischemic region (anterior wall) with myocardial contrast echocardiography decreased obviously after the left anterior descending artery was ligated (Laser group: 5, 40 +/- 1.81, Needle group: 7.11 +/- 2.51) compared with that before (Laser group: 11.69 +/- 1.61, Needle group: 12.96 +/- 2.88, P < 0.01). dB increased remarkably after TMR by either laser or True-cut biopsy needle (Laser group: 11.02 +/- 2.01, Needle group: 10.01 +/- 4.45. P < 0.01) compared to that during ischemia and approximated to that before ischemia (P > 0.05). We found that the acoustic density of the contrast developed one picture (one cardiac cycle) ahead in the transmyocardial revascularization region than that in the lateral and other region of the left ventricle wall in the scan of both groups. CONCLUSIONS: Acute ischemic myocardium can be perfused immediately by oxygenated blood from the left ventricle through channels created with both Ho-Yag laser and True-cut biopsy needles. Evidence of blood perfusion through these channels mainly during systolic phase was detected, and myocardial contrast ultrasound using intravenous perfluorocarbon-exposed sonicated dextrose albumin was regarded as a reliable method in the study of transmyocardial revascularization.

Animals↗

PubMed2000

New syntheses of the C,D-ring pyrromethenones of phytochrome and phycocyanin.

Pyrromethenone 7, the C,D-ring segment of phytochrome (Pr, 4), has been prepared in an efficient fashion employing three new strategies. Each of these has potential advantages for the synthesis of labeled material. Our first approach is related to the Gossauer synthesis, with the difference that strong alkali is avoided in the condensation of the C- and D-ring components 8 and 17. The key silyloxypyrrole 17 was readily prepared on multigram scales beginning with inexpensive butyrolactone (10). A second synthesis began with 2-acetylbutyrolactone (41). The key steps involved conversion of 41 to the Z-enoltriflate 42, followed by Pd(0)-catalyzed coupling with trimethylsilylacetylene, p-chlorophenylselenide ring opening, and finally, amidation to afford the ring-D synthon 45 having the proper geometry and oxidation state for conversion to 7. Sonogashira coupling of 45 with the iodopyrrole 22, followed by oxidative elimination, and F(-)-induced 5-exo-dig cyclization of the resultant pyrroloalkyne 47, then completed the synthesis. In similar fashion, we have also prepared pyrromethenone 6, the C,D-ring segment of phycocyanin (2).

Magnetic Resonance Spectroscopy↗

PubMed2000

A new pathway of translational regulation mediated by eukaryotic initiation factor 3.

We report a new pathway of translation regulation that may operate in interferon-treated or virus-infected mammalian cells. This pathway is activated by P56, a protein whose synthesis is strongly induced by interferons or double-stranded RNA. Using a yeast two-hybrid screen, we identified the P48 subunit of the mammalian translation initiation factor eIF-3 as a protein that interacts with P56. The P56-P48 interaction was confirmed in human cells by co-immunoprecipitation assays and confocal microscopy. Gel filtration assays revealed that P56 binds to the large eIF-3 complex that contains P48. Purified recombinant P56 inhibited in vitro translation of reporter mRNAs in a dose-dependent fashion, and that inhibition was reversed by the addition of purified eIF-3. In vivo, expression of transfected P56 or induction of the endogenous P56 by interferon caused an inhibition of overall cellular protein synthesis and the synthesis of a transfected reporter protein. As expected, a P56 mutant that does not interact with P48 and eIF-3 failed to inhibit protein synthesis in vitro and in vivo.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Heterologous activation of protein kinase C stimulates phosphorylation of delta-opioid receptor at serine 344, resulting in beta-arrestin- and clathrin-mediated receptor internalization.

The purpose of the current study is to investigate the effect of opioid-independent, heterologous activation of protein kinase C (PKC) on the responsiveness of opioid receptor and the underlying molecular mechanisms. Our result showed that removing the C terminus of delta opioid receptor (DOR) containing six Ser/Thr residues abolished both DPDPE- and phorbol 12-myristate 13-acetate (PMA)-induced DOR phosphorylation. The phosphorylation levels of DOR mutants T352A, T353A, and T358A/T361A/S363S were comparable to that of the wild-type DOR, whereas S344G substitution blocked PMA-induced receptor phosphorylation, indicating that PKC-mediated phosphorylation occurs at Ser-344. PKC-mediated Ser-344 phosphorylation was also induced by activation of G(q)-coupled alpha(1A)-adrenergic receptor or increase in intracellular Ca(2+) concentration. Activation of PKC by PMA, alpha(1A)-adrenergic receptor agonist, and ionomycin resulted in DOR internalization that required phosphorylation of Ser-344. Expression of dominant negative beta-arrestin and hypertonic sucrose treatment blocked PMA-induced DOR internalization, suggesting that PKC mediates DOR internalization via a beta-arrestin- and clathrin-dependent mechanism. Further study demonstrated that agonist-dependent G protein-coupled receptor kinase (GRK) phosphorylation sites in DOR are not targets of PKC. Agonist-dependent, GRK-mediated receptor phosphorylation and agonist-independent, PKC-mediated DOR phosphorylation were additive, but agonist-induced receptor phosphorylation could inhibit PKC-catalyzed heterologous DOR phosphorylation and subsequent internalization. These data demonstrate that the responsiveness of opioid receptor is regulated by both PKC and GRK through agonist-dependent and agonist-independent mechanisms and PKC-mediated receptor phosphorylation is an important molecular mechanism of heterologous regulation of opioid receptor functions.

Arrestins↗

PubMed2000

Induction and expression of beta-calcitonin gene-related peptide in rat T lymphocytes and its significance.

Our previous data have shown that rat lymphocytes can synthesize calcitonin gene-related peptide (CGRP), a neuropeptide. In this study the type, characteristics, and functional role of lymphocyte-derived CGRP were investigated. The results showed that treatment with Con A (4 microg/ml) and recombinant human IL-2 (rhIL-2; 750 U/ml) for 3-5 days induced CGRP synthesis and secretion by lymphocytes from both thymus and mesenteric lymph nodes in a time-dependent manner. Stimulation of these cells with Con A (1-8 microg/ml) or rhIL-2 (94-1500 U/ml) for 5 days induced a significant increase in CGRP secretion in a concentration-dependent manner. The maximal secretion of CGRP with Con A by thymocytes was elevated from 104+/-11 to 381 +/- 44 pg/10(8) cells, and that by mesenteric lymph node lymphocytes was elevated from 83+/-10 to 349+/-25 pg/10(8) cells, respectively. The maximal CGRP secretion with rhIL-2 by thymocytes was elevated from 116+/-3 to 607+/-23 pg/10(8), and that by mesenteric lymph node lymphocytes was elevated from 117+/-9 to 704+/- 37 pg/10(8) cells, respectively. The nucleotide sequencing study showed that lymphoid cells expressed beta-CGRP cDNA only. The levels of beta-CGRP mRNA in mitogen-stimulated lymphocytes of both sources were also increased. However, LPS had no such effect on either source of cells. hCGRP(8-37) (2.0 microM), a CGRP(1) receptor antagonist, enhanced Con A-induced proliferation and IL-2 release of thymocytes by 41.3 and 35.8% over those induced by Con A alone, respectively. The data suggest that T lymphocyte mitogens can induce the production of endogenous beta-CGRP from T lymphocytes, which may partially inhibit the proliferation and IL-2 release of rat T lymphocyte under immune challenges.

Animals↗

PubMed2000

A mechanism for plus-strand transfer enhancement by the HIV-1 nucleocapsid protein during reverse transcription.

The HIV-1 nucleocapsid protein (NC) functions as a nucleic acid chaperone during the plus-strand transfer step in reverse transcription by facilitating annealing of the primer binding site (PBS) sequence in the short plus-strand strong-stop DNA fragment [(+) SSDNA] to a complementary site located near the 3' end of the minus-strand DNA [(-) PBS DNA]. To investigate the mechanism by which NC performs this function, we have prepared an 18-nucleotide (-) PBS DNA for nuclear magnetic resonance (NMR) based structural and NC binding studies. The (-) PBS DNA forms a stable hairpin (T(m) approximately 42 +/- 5 degrees C) that contains a five-residue loop and a bulged thymine in a guanosine-cytosine-rich stem. Addition of substoichiometric amounts of NC results in significant broadening and reductions in NMR signal intensities of the Watson-Crick base-paired imino protons and a reduction by 20 degrees C in the upper temperature at which the imino proton signals are detectable, consistent with destabilization of the structure. The results suggest that inefficient annealing in the absence of NC may be due to the intrinsic stability of an internal (-) PBS DNA hairpin and that NC facilitates strand transfer by destabilizing the hairpin and exposing stem nucleotides for base pairing with the PBS sequence in (+) SSDNA.

Binding Sites↗

PubMed2000

TACI is a TRAF-interacting receptor for TALL-1, a tumor necrosis factor family member involved in B cell regulation.

We and others recently reported tumor necrosis factor (TNF) and apoptosis ligand-related leukocyte-expressed ligand 1 (TALL-1) as a novel member of the TNF ligand family that is functionally involved in B cell proliferation. Transgenic mice overexpressing TALL-1 have severe B cell hyperplasia and lupus-like autoimmune disease. Here, we describe expression cloning of a cell surface receptor for TALL-1 from a human Burkitt's lymphoma RAJI cell library. The cloned receptor is identical to the previously reported TNF receptor (TNFR) homologue transmembrane activator and calcium modulator and cyclophilin ligand (CAML) interactor (TACI). Murine TACI was subsequently isolated from the mouse B lymphoma A20 cells. Human and murine TACI share 54% identity overall. Human TACI exhibits high binding affinities to both human and murine TALL-1. Soluble TACI extracellular domain protein specifically blocks TALL-1-mediated B cell proliferation without affecting CD40- or lipopolysaccharide-mediated B cell proliferation in vitro. In addition, when injected into mice, soluble TACI inhibits antibody production to both T cell-dependent and -independent antigens. By yeast two-hybrid screening of a B cell library with TACI intracellular domain, we identified that, like many other TNFR family members, TACI intracellular domain interacts with TNFR-associated factor (TRAF)2, 5, and 6. Correspondingly, TACI activation in a B cell line results in nuclear factor kappaB and c-Jun NH(2)-terminal kinase activation. The identification and characterization of the receptor for TALL-1 provides useful information for the development of a treatment for B cell-mediated autoimmune diseases such as systemic lupus erythematosus.

Amino Acid Sequence↗

PubMed2000

Adsorption of PBTCA on Alumina Surfaces and Its Influence on the Fractal Characteristics of Sediments.

The adsorption of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) on Al(2)O(3) powder has been studied as a function of pH and concentration. The adsorption density of PBTCA is found to decrease with an increase of pH. Zeta potential measurements show that the addition of PBTCA results in a dramatic increase in the absolute zeta potential, as well as a shift of the isoelectric point to the more acidic region. PBTCA considerably enhances the stability of the alumina suspension via an electrostatic mechanism. The surface properties of alumina suspensions are examined by using Auger electron microscopy and FTIR analysis. Chemical interactions take place at the solid/water interface by forming complexes between Al(3+) ions and PBTCA. The dispersing ability of PBTCA is believed to be related to its high adsorption ability and the high number of dissociable protons. The morphology of the sediments is observed with scanning electron microscopy. It is found that the sediment surfaces exhibit fractal characteristics. The fractal dimension values of sediments are correlated with PBTCA concentration in the experimental range. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Cutting edge: introduction of an endopeptidase cleavage motif into a determinant flanking region of hen egg lysozyme results in enhanced T cell determinant display.

The choice of which determinants of a whole Ag will be presented on cell surface MHC class II molecules after uptake and processing by APC is the result of the interplay between structural characteristics of the Ag and the processing machinery of the APC. In this study, we demonstrate that introduction of a dibasic motif adjacent to a subdominant determinant enhances the presentation of this determinant from the whole molecule. This is the first report showing that a single amino acid substitution in a whole Ag, designed to introduce an endopeptidase recognition site, enhances display of class II-restricted determinants, most likely by creating a peptide chain cleavage in the antigenic molecule. Our findings have important implications for the understanding of immunodominance and for vaccine design.

Amino Acid Motifs↗

PubMed2000

[Mechanism of impairment to microtubule polymerization resulting from zinc deficiency during pregnancy and lactation in mice].

To probe into the mechanism of zinc deficiency on microtubule polymerization impairment, the learning ability and the levels of alpha-tubulin, beta-tubulin and microtubule-associated protein 2 expression in the brain of zinc deficient offsprings, maternal ICR mice were fed with experiment diets containing different levels of zinc(1, 5, 30 and 100 mg/kg) during pregnancy and lactation respectively. On the postnatal day 70 of offsprings, the learning ability and the expression of alpha-tubulin, beta-tubulin and microtubule-associated protein 2 in the brain were examined by shuttle box and Western blot assays respectively. The results showed that the number of trials needed to reach the learning criterion for zinc deficient groups (1 and 5 mg/kg) was much higher than that for non zinc deficient groups (30 and 100 mg/kg). The levels of alpha-tubulin, beta-tubulin and microtubule-associated protein 2 expression in the brain of zinc deficient offsprings (1 and 5 mg/kg) were lower than those in the brain of offsprings whose dams fed with zinc adequately supplied diet (30 mg/kg) and zinc supplemented supplied diet (100 mg/kg) respectively. These results suggested that the inhibition of alpha-tubulin, beta-tubulin and microtubule-associated protein 2 expression might be the most important mechanism of microtubule polymerization decline resulting from zinc deficiency, which had close relationship with brain function impairment.

Animals↗