Biomedical subjects

J Luo

Publications and source records attributed to J Luo.

At least 91 records · Page 5Linked to original sources

PubMed2001

[Construction of rice dwarf virus genome database].

Secondary database construction is an important subject in the field of bioinformatics. As the full genomic sequences of some organisms are being completed and followed by structural and functional studies, construction of secondary database becomes essential on the agenda. The rice dwarf virus (RDV) is a pathogen infecting rice in China, Japan and the Southeastern Asia region and leading to considerable economic loss. Based on the data generated from recent genomic research and earlier biochemical studies scattered in various primary databases and scientific journals, we have constructed a compact, user-friendly and non-redundant job-oriented secondary database. This work will provide compiled useful information for plant molecular biologists as well as in achieving preliminary experiences in secondary database construction.

Databases, Factual↗

PubMed2001

[A new triterpene from the fruiting bodies of Ganoderma lucidum].

AIM: To study the chemical constituents of the fruiting bodies of Ganoderma lucidum. METHODS: Individual constituents, isolated and repeatedly purified on silica gel column, were identified by physicochemical constants and structurally elucidated by spectral methods. RESULTS: From the alcohol extract, compound 2 was obtained and identified as 3 beta,7 beta-dihydroxy-4,4,14 alpha-trimethyl-11,15-dioxo-5 alpha-chol-8-en-24-oic acid. In addition, two known compounds, lucidenic acid A (1) and C (3) were obtained. CONCLUSION: Compound 2 is a new triterpene compound.

Cholic Acids↗

PubMed2001

[Analysis of essential oil from Artemisia annul L. by extraction of different methods].

Essential oils from Artemisia annul L. were extracted with CO2 supercritical fluid and steam distilation. The essential oils were analyzed and contrasted by GC-MS. 114 components were identified by computer index. The rate of total components by supercritical CO2 fluid extraction and steam distillation were 81.24% and 85.75% respectively. Some of them such as diphenylene-Methane, Phenyl-1-naphthylamine were discovered from the plant for the first time.

1-Naphthylamine↗

PubMed2001

[Influence of different collection time on yield and constituents of essential oil of herba pogostemonis from Gaoyao County].

The constituents of the volatile oil of Herba Pogostemonis from Gaoyao county collected at various different time by GC/MS combination technology were analysed and compared. The results showed that the average dry weight of single plant(i.e. yield) increased gradually from July to next April, the content of volatile oil was highest in November. The contents of pogostemone in the leaf oil were higher in July and September, then decreased gradually with growth time; pachouli alcohol was higher in September, October and November, lower in other months. The contents of pogostmone in stem oil were higher in July, October and next January, lowest in November. The content change of pachouli alcohol in stem oil were not obvious in all growth time, higher slightly only after November. Other compounds were not showed their variation law. So the quality of Herba Pogostemonis collected in November was higher if the content of volatile oil was used as a standard of quality evaluation, the result was in accordance with traditional collection experience.

Drugs, Chinese Herbal↗

PubMed2001

[Studies on the triterpenoidal saponins from flowers of Eriobotrya japonica].

OBJECTIVE: To investigate the chemical composition of the flowers of Eriobotrya japonica. METHODS: Four constituents were isolated from the ethanolic extracts of flowers of Eriobotrya japonica (Thunb) Lindl and were identified by chemical methods and spectroscopic (IR, MS, 1HNMR, 13CNMR). RESULTS: The structures were identified as: Oleanolic acid (I), Ursolic acid(II), 2 alpha, 3 alpha, 19 alpha-Trihydroxyurs-5,12-dien-28-acid (III) and 2 beta, 3 beta, 23 alpha-Trihydroxyolean-12-en-28-acid (IV). CONCLUSION: The compounds I, II, III and IV were obtained from the flowers of Eriobotrya japonica for the first time.

Eriobotrya↗

PubMed2001

[Fabrication of cartilage in predetermined shapes from human nasoseptal chondrocytes with tissue engineering method].

OBJECTIVE: To investigate the feasibility of fabricating a new cartilage in predetermined shapes with tissue engineering methods. METHODS: Human nasoseptal chondrocytes were seeded onto a nonwoven mesh of polyglycolic acid(PGA) to form a cell-PGA construct. The construction was then configured in sheet and tube shapes, and implanted subcutaneously into the dorsa of 11 athymic mice. The specimens were harvested 4, 6, 8 weeks after implantation and subjected to gross morphologic and histologic analysis. RESULTS: Gross observation showed that the predetermined sheet and tube shapes of new cartilage were formed. Histological observation demonstrated that new mature cartilages were formed in 6-week. A Masson's trichrome stain showed the interwining bands of collagen at the periphery of the cartilage. Staining of Safranin O evaluated that the new cartilage was bound of glycosaminoglycan. In the control group, the PGA of the specimens were completely absorbed at 6 weeks. CONCLUSION: Human nasoseptal chondrocytes-PGA construct could develop into a new cartilage in predetermined shapes in athymic mice.

Animals↗

PubMed2001

[Fabrication of allogeneic cartilage with tissue engineering technique and repair of laryngeal cartilage defects in rabbits].

OBJECTIVE: To investigate the fabrication of allogeneic tissue engineered cartilage in predetermined shapes and its ability to repair laryngeal cartilage defects. METHODS: Tissue engineering technique was used to make allogeneic tissue engineered cartilage in predetermined shapes, and then some of them were utilized to repair cartilage defects in the rabbit larynges(n = 12). Finally, the chondrogenesis and reparative effect were studied grossly and histologically at various periods. RESULTS: 1. The gross specimens of 4 weeks after implantation revealed the presence of new hyaline cartilage of approximately the same shapes as original predetermined shapes, which had fair elasticity and support ability. Histological evaluation showed the characteristics of cartilage tissue. 2. Laryngeal cartilage defects were well repaired using allogeneic tissue engineered cartilage in different periods after operation. A few chondrocytes were observed between the reparative areas with tissue engineered cartilage and normal cartilage. Abundant matrices were also detected in the reparative and interfacial areas. No inflammatory cells were found. CONCLUSION: It is possible to regenerate new cartilage in predetermined shapes using tissue engineering technique in allograft animals with immunity. Allogeneic tissue engineered cartilage can be used as reparative material to repair cartilage defect of rabbit larynx.

Animals↗

PubMed2001

[Morphological, microscopical and UV spectral identification of herba visci ovalifolii].

OBJECTIVE: To identify herba Visci ovalifolii, Chinese medicinal materials used in Li and Miao nationalities. METHODS: Morphological, microscopical and UV spectral methods. RESULT: Dichotomous branch with a yellow surface, with leaf of 3-5 acrodromous veins originating at the base of the leaf. In transverse section, the thick outer wall of the epidermis of stem projecting like nipple; stone cells contain frequently a prismatic crystal of calcium oxalate, often occur in the cortex and phloem of the stem. Pericycle fibres and xylem fibres all with a well-developed thick wall; vessels with a bordered pits somtimes have a spiral thickened interwall; mesophyll homogeneous contain cluster crystals (not calcium oxalate); stomata present on both surfaces, mostly paracrytic, with small and narrow subsidiary cells. Hairs absent at the surface. CONCLUSION: Above morphological and microscopical characters may be used for the identification of herba Visci ovalifolii. UV spectral method is a simple identificating method for herba Visci ovalifolii.

Drugs, Chinese Herbal↗

PubMed2000

Deacetylation of p53 modulates its effect on cell growth and apoptosis.

The p53 tumour suppressor is a transcriptional factor whose activity is modulated by protein stability and post-translational modifications including acetylation. The mechanism by which acetylated p53 is maintained in vivo remains unclear. Here we show that the deacetylation of p53 is mediated by an histone deacetylase-1 (HDAC1)-containing complex. We have also purified a p53 target protein in the deacetylase complexes (designated PID; but identical to metastasis-associated protein 2 (MTA2)), which has been identified as a component of the NuRD complex. PID specifically interacts with p53 both in vitro and in vivo, and its expression reduces significantly the steady-state levels of acetylated p53. PID expression strongly represses p53-dependent transcriptional activation, and, notably, it modulates p53-mediated cell growth arrest and apoptosis. These results show that deacetylation and functional interactions by the PID/MTA2-associated NuRD complex may represent an important pathway to regulate p53 function.

Acetylation↗

PubMed2000

Isolation and characterization of coenzyme A glutathione disulfide as a parathyroid-derived vasoconstrictive factor.

BACKGROUND: Coenzyme A glutathione disulfide (CoA-SSG) was recently isolated from bovine adrenal glands and was shown to be a renal vasoconstrictor. The identification of CoA-SSG in human parathyroid glands and its action on cultured vascular smooth muscle cells (VSMCs) are described here. METHODS AND RESULTS: After purification to homogeneity by several chromatographic steps, CoA-SSG was identified by matrix-assisted laser desorption/ionization mass spectrometry and enzymatic analysis. The dose-dependent growth-stimulating effect of CoA-SSG on VSMCs, measured by the [(3)H]thymidine method, is characterized by a threshold of 10(-)(8) mol/L and a maximum effect of 10 micromol/L, increasing VSMC proliferation 254+/-21% above control. A dose of 10 micromol/L methylmalonyl-CoA and 10 micromol/L CoA increased the rate of proliferation of VSMCs only by 178+/-43% and 50+/-42% above control, respectively. Glutathione has no proliferative effect on VSMCs. The growth-stimulating effect of CoA-SSG (1 micromol/L) was decreased by the antagonists 3,7-dimethyl-1-propargylxanthine (DMPX; 11 micromol/L) (38% compared with CoA-SSG without antagonist) and pyridoxal-phosphate-6-azophenyl-2,4-disulfonic acid (PPADS; 10 micromol/L) (48% compared with CoA-SSG without antagonist; each P:<0. 05 versus control), indicating that the effect is mediated partly via A(2) and partly via P(2)Y(1) and/or P(2)Y(4) receptor. CONCLUSIONS: CoA-SSG may play a regulatory role in VSMC growth as a progression factor and thereby could play an important role in development of hypertension.

Acetates↗

PubMed2000

Structure-function study and anti-HIV activity of synthetic peptide analogues derived from viral chemokine vMIP-II.

The viral macrophage inflammatory protein II (vMIP-II) shows a broad spectrum interaction with both CC and CXC chemokine receptors including CCR5 and CXCR4, two principal coreceptors for the cellular entry of human immunodeficiency virus type 1 (HIV-1). Recently, we have shown that a synthetic peptide derived from the N-terminus of vMIP-II, designated as V1, is a potent antagonist of CXCR4 but not CCR5 [Zhou, N., et al. (2000) Biochemistry 39, 3782-3787]. In this study, we synthesized a series of new peptides derived from other regions of vMIP-II and characterized their binding activities with both CXCR4 and CCR5. The results provided further support for the notion that the N-terminus of vMIP-II is the major determinant for CXCR4 recognition and that vMIP-II probably interacts with other chemokine receptors such as CCR5 with different sequence and conformational determinants. To understand the structure-function relationship of V1 peptide, its solution conformation was studied using circular dichroism spectroscopy, which showed a random conformation similar to that of the corresponding N-terminus in native vMIP-II. In addition, we synthesized a series of mutant analogues of V1 containing alanine, glycine, or phenylalanine substitution at various positions. Residues Val-1, Arg-7, and Lys-9 of V1 peptide were found to be critical for receptor interaction, because single alanine replacement at these positions dramatically decreased peptide binding to CXCR4. In contrast, alanine or phenylalanine substitution at Cys-11 led to significant enhancement in peptide affinity for CXCR4. Finally, we showed that V1 peptide inhibits HIV-1 replication in CXCR4(+) T-cell lines. These studies provide new insights into the structure-function relationship of V1 peptide and demonstrate that this peptide may be a lead for the development of therapeutic agents.

Alanine↗

PubMed2000

Surfactant protein genetic marker alleles identify a subgroup of tuberculosis in a Mexican population.

Pulmonary surfactant and its components are essential for normal lung function and are involved in local host defense. Surfactant protein (SP)-A and SP-D bind to and modulate phagocytosis of Mycobacterium tuberculosis by macrophages. Frequency comparisons of SP marker alleles in tuberculosis patients and healthy control subjects (tuberculin-skin test positive or general population) were performed. Regression analyses of the tuberculosis and the tuberculin-skin test positive groups revealed, on the basis of odds ratios, tuberculosis susceptibility (DA11_C and GATA_3) and protective (AAGG_2) marker alleles. Similarly, between tuberculosis patients and general population control subjects, susceptibility 1A(3), 6A(4), and B1013_A and protective AAGG_1, and AAGG_7 marker alleles were observed. Moreover, interactions were seen between alleles 6A(2) and 1A(3) (P=.0064) and between 1A(3) and B1013_A (P=. 036). The findings indicate a possible involvement of SP alleles in tuberculosis pathogenesis.

Adult↗

PubMed2000

Novel antihyperglycemic terpenoid-quinones from Pycnanthus angolensis.

Two new compounds, pycnanthuquinone A (1) and pycnanthuquinone B (2), were isolated from leaves and stems of the African plant, Pycnanthus angolensis (Welw.) Warb (Myristicaceae), by bioassay-guided fractionation of an ethanolic extract using a diabetic mouse model. Pycnanthuquinones A and B are the first representatives of a novel terpenoid-type quinone skeleton, and both compounds possess significant antihyperglycemic activity.

Africa↗

PubMed2000

Racial differences in tamoxifen metabolism.

PURPOSE: A recent study indicates that black women may have a higher risk/benefit ratio from tamoxifen than white women. Several reports in the literature indicate that racial differences in the risks/benefits from other pharmaceutical agents may be partially due to racial differences in drug metabolism. Thus, we explore the hypothesis that the racial difference in the tamoxifen risk/benefit ratio may be due, in part, to racial differences in tamoxifen metabolism.METHODS: We conducted a pilot study in which we recruited 6 white and 4 black breast cancer patients from the Baltimore, Maryland area. All patients were taking tamoxifen for at least 30 days. Each provided a blood sample that was used to measure tamoxifen metabolites by high performance liquid chromatography.RESULTS: Our results indicate that the black women had significantly higher levels of the tamoxifen metabolite, N-desmethyltamoxifen (N-DMT) than the white women (0.585 µg/ml vs 0.199 µg/ml, p < 0.05). There were no differences in the serum levels of tamoxifen in black and white women (0.809 vs 0.699, p > 0.1).CONCLUSIONS: These data suggest that both black and white breast cancer patients reach steady state tamoxifen levels, but that black women are more likely to metabolize tamoxifen to N-DMT or to maintain higher levels of N-DMT (i.e., less excretion of N-DMT) than white women. N-DMT is thought to be less effective in breast cancer treatment than tamoxifen. N-DMT also has been associated with excess proliferation in breast cancer cells. Thus, it is possible that the relatively high tamoxifen risk/benefit in black women occurs because tamoxifen is readily converted to N-DMT in black women, but not in white women. Although the data reported here are from a pilot study, it is important to note that significant racial differences in tamoxifen metabolism were observed with only a few participants. We urge other investigators to confirm these findings using a large population of breast cancer patients.

Journal Article↗

PubMed2000

The fluorescent characterization of the polymerized microtubule-associated protein Tau.

A new fluorescence formed while microtubule-associated protein tau was incubated at 25 and 37C for hours, with its maximum excitation at 230 and 280 nm, respectively. The fluorescence completely formed after tau was incubated in phosphate buffer and Tris-HCl buffer for approximately 20 h, with a relaxation phase about 2-4 h. The light scattering of the sample solution improved during formation of the fluorescence when tau was incubated. Both the fluorescence and tau oligomers did not form when tau was incubated in the buffers containing DTT. On the other hand, heparin improved both tau aggregation and the fluorescence formation. It suggests that the fluorescence comes from tau polymerization, which may follow the mechanism of tyrosine-tyrosinate emission for a protein not containing any tryptophan residues. This new fluorescence could be used as a probe to tau polymers.

Buffers↗

PubMed2000

Requirement for glycogen synthase kinase-3beta in cell survival and NF-kappaB activation.

Glycogen synthase kinase-3 (GSK-3)-alpha and -beta are closely related protein-serine kinases, which act as inhibitory components of Wnt signalling during embryonic development and cell proliferation in adult tissues. Insight into the physiological function of GSK-3 has emerged from genetic analysis in Drosophila, Dictyostelium and yeast. Here we show that disruption of the murine GSK-3beta gene results in embryonic lethality caused by severe liver degeneration during mid-gestation, a phenotype consistent with excessive tumour necrosis factor (TNF) toxicity, as observed in mice lacking genes involved in the activation of the transcription factor activation NF-kappaB. GSK-3beta-deficient embryos were rescued by inhibition of TNF using an anti-TNF-alpha antibody. Fibroblasts from GSK-3beta-deficient embryos were hypersensitive to TNF-alpha and showed reduced NF-kappaB function. Lithium treatment (which inhibits GSK-3; refs 8, 9) sensitized wild-type fibroblasts to TNF and inhibited transactivation of NF-kappaB. The early steps leading to NF-kappaB activation (degradation of I-kappaB and translocation of NF-kappaB to the nucleus) were unaffected by the loss of GSK-3beta, indicating that NF-kappaB is regulated by GSK-3beta at the level of the transcriptional complex. Thus, GSK-3beta facilitates NF-kappaB function.

Animals↗

PubMed2000

Selective somatostatin sst(2) receptor blockade with the novel cyclic octapeptide, CYN-154806.

The cyclic octapeptide, CYN-154806, inhibited specific [(125)I]-[Tyr(11)]-SRIF binding to CHO-K1 cell membranes expressing human recombinant somatostatin (SRIF) sst(2) receptors (pIC(50) 8. 58) or rat sst(2(a)) and rat sst(2(b)) receptors (pIC(50) 8.35 and 8. 10, respectively). The affinity of CYN-154806 at other human somatostatin receptor types was at least 100 times lower (pIC(50) 5. 41-6.48). In functional studies, CYN-154806 inhibited SRIF-induced increases in extracellular acidification (EAR) in CHO-K1 cells expressing h sst(2) receptors (pK(B) 7.92) but had no effect on UTP-induced increases in EAR. CYN-154806 also blocked SRIF-induced increases [(35)S]-GTPgammaS binding in CHO-K1 cell membranes expressing h sst(2) receptors as well as rat sst(2(a)) and rat sst(2(b)) receptors (pK(B) 7.81, 7.68 and 7.96, respectively). In marked contrast, no blockade was observed at h sst(5) receptors in concentrations as high 10 microM. The antagonistic activity of CYN-154806 was also studied in isolated tissue preparations that are known to express endogenous SRIF receptors. Thus CYN-154806 blocked SRIF, but not DAMGO-induced inhibition of neurogenic contractions in rat isolated vas deferens and guinea-pig ileum (pK(B) 7.79 and 7.49, respectively). CYN-154806 had no effect on SRIF-28 induced inhibition of neurogenic contractions in guinea-pig vas deferens. The results demonstrate that CYN-154806 is a highly potent specific and selective SRIF sst(2) receptor blocking drug. Furthermore, sst(2) receptors mediate SRIF-induced inhibition of neurogenic contractions in rat vas deferens and guinea-pig ileum but not guinea-pig vas deferens which is thought to be mediated by sst(5) receptors.

Analgesics, Opioid↗

PubMed2000

Ruthenium bisbipyridine complexes of horse heart cytochrome c: characterization and comparative intramolecular electron-transfer rates determined by pulse radiolysis and flash photolysis.

The reaction of [Ru(bpy)2L(H2O)]2+ (bpy = 2,2'-bipyridine, L = imidazole, water) with reduced horse heart cytochrome c results in coordination of [RuII(bpy)2L] at the His 33 and His 26 sites. Coordination at the His 33 site gave a diastereomeric [RuII(bpy)2L]-His-cyt c(II) mixture favoring the lambda-Ru form regardless of the substituent on the bipyridine ligands, while substitution at the more buried His 26 site gave an isomeric distribution that varies according to the substituent on the bipyridine ligands. The diastereomeric aquoproteins (L = H2O) are distinguished by their redox potentials and their conversion to the corresponding fluorescent imidazole proteins. Intramolecular electron transfer between the reduced ruthenium bipyridine and cyt c(III) in [RuII(bpy.)(bpy)L]-His33-cyt c(III) was determined by reductive pulse radiolysis using the aqueous electron as a reducing agent, kret = (2.0 +/- 0.3) x 10(5) s-1, and kret is independent of the sixth ligand L = H2O, imidazole. In addition, the rate constant for intramolecular electron transfer from cyt c(II) to the ruthenium(III) center in [RuIII(bpy)2L]-His33-cyt c(II) was determined by oxidative pulse radiolysis using azide and carbonate radicals. This rate is very sensitive to the nature of the sixth ligand. When L = H2O, the intramolecular electron-transfer rate for the major diastereomer lambda-cis-[RuIII (bpy)2(H2O)]-His33-cyt c(II) is k = 1.1 x 10(4) s-1 and is independent of pH between 5.6 and 8.3. The minor delta-cis-[RuIII(bpy)2(H2O)]-His33-cyt c(II) isomer has pH-dependent electrochemistry and a lower rate of intramolecular electron transfer. Complete conversion from L = H2O to L = imidazole is slow, requiring more than 7 days in 1 M imidazole. A lower limit (k > 2 x 10(6) s-1) for the intramolecular electron-transfer rate constant in [RuIII(bpy)2(L)]-His33-cyt c(II), L = imidazole, could be obtained by pulse radiolysis in the absence of the slower reacting aquo species. This observation is in agreement with the value of 3 x 10(6) s-1 measured by flash photolysis. Earlier pulse radiolysis experiments primarily measured the aquoligated ruthenium protein, while the flash photolysis experiments measured the imidazole-ligated fraction because it is the only species oxidatively quenched in the photoinduced reactions. Intramolecular electron-transfer reactions for a new series of ruthenium bipyridine complexes, [Ru(dabpy)2L]-His33-cyt c proteins (dabpy = 4,4'-diamino-2,2'-bipyridine) (L = imidazole, pyridine, isonicotinamide and pyrazine), proceed with lower driving force, resulting in slower rate constants amenable to measurement by oxidative pulse radiolysis. The electron-transfer rate constants for this series spanned a wide range of the Marcus log k vs delta G plot.

Animals↗