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Biomedical subjects

G X Zhou

Publications and source records attributed to G X Zhou.

18 recordsLinked to original sources
PubMed2000

New annonaceous acetogenins from the roots of Uvaria calamistrata.

Five new annonaceous acetogenins, calamistrins C-G (1-5), were isolated from an ethanolic extract of the roots of Uvaria calamistrata. Compounds 1-3 were mono-THF ring acetogenins; compounds 4 and 5 were bis-THF acetogenins, with the THF rings from C-18 to C-25. The absolute configurations of 3, 4, and 5 as well as the partial absolute configurations of 1 and 2 were determined by (13)C NMR spectroscopy and advanced Mosher methodology.

Drug Screening Assays, Antitumor↗
PubMed2000

Polyoxygenated bipyridine, pyrrolylpyridine, and bipyrrole alkaloids from Speranskia tuberculata.

Five novel polyoxygenated alkaloids, speranculatines A-C (3-5), speranskilatine A (6), and speranberculatine A (7), have been isolated from Speranskia tuberculata. Compounds 3-5, 6, and 7, have bipyridine, pyrrolylpyridine, and bipyrrole skeletons, respectively. This is the first time that these three alkaloid structural types have been reported. The structures of 3-7 were elucidated by spectroscopic methods, including 2D NMR techniques and X-ray crystallographic analysis.

Alkaloids↗
PubMed1999

Calamistrins A and B, two new cytotoxic monotetrahydrofuran annonaceous acetogenins from Uvaria calamistrata.

Two new bioactive monotetrahydrofuran acetogenins, calamistrins A (1) and B (2), and two known compounds, uvarigrin (3) and uvarigranin (4), have been isolated from the roots of Uvaria calamistrata. The structures of the new compounds were elucidated by spectroscopic and chemical methods. The absolute stereochemistry of the stereogenic centers was established by Mosher ester methodology.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Styryllactones from the rhizomes of Goniothalamus griffithii.

Three new styryl-lactones 8-acetylgoniofufurone(1), 7-acetylgonio-pypyrone(3), and 5-acetylgoniopypyrone(4), along with ten known compounds, goniofufurone(2), goniopypyrone(5), goniothalamin, goniothalenol, (+)-isoaltholactone, goniodiol, 7-acetylgoniodiol, goniotriol, 8-acetylgoniotriol, 9-deoxygoniopypyrone were isolated from the rhizomes of Goniothalamus griffithii Hook f. et. Thoms. Their structures were elucidated by IR, MS, NMR spectra and chemical evidence. All compounds showed cytotoxic activities against human cancer cell lines.

Lactones↗
PubMed1999

New polyoxygenated cyclohexenes from Uvaria calamistrata.

Five new polyoxygenated cyclohexenes, named uvacalol A (1), B (2), C (3), D (4) and E (5) were isolated from the roots of Uvaria calamistrata. On the basis of spectral analysis and chemical derivatization, including the preparation of Mosher esters, the structures of compound 1-5 were established as (2R,3S,4R,5S)-2-acetoxyl-5-ethoxyl-1-benzoyloxymethylcyclohex-1(6)-ene3,4-diol-3-benzoate, (2R,3S,4R,5S)-2-acetoxyl-5-ethoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-3,4-diol-4-benzoate, (2R,3S,4R,5S)-5-ethoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-2,3,4-triol-3-benzoate, (2R,3S,4R,5S)-3-methoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-2,3,5-triol and (2R,3S,4R,5S)-2-acetoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-3,4,5-triol-5-benzoate, respectively.

Alcohols↗
PubMed1996

Antibodies to endometrial transferrin and alpha 2-Heremans Schmidt (HS) glycoprotein in patients with endometriosis.

PROBLEM: Identifying the endometrial antigens inciting autoimmunity is important in setting up an antibody assay for a non-invasive diagnosis and clinical monitoring of endometriosis. METHODS: Two-dimensional gel electrophoresis of endometrial extracts, Western blot analysis, passive hemagglutination and enzyme-linked immunosorbent assay (ELISA), amino acid sequencing and molecular studies were done on chosen antigens. Forty-six women with endometriosis, 4 women with uterine leiomyomata, 4 with pelvic adhesions, 3 with repeat Cesarean sections (conditions that coexist with or predispose to endometriosis) and 46 controls participated. RESULTS: Antigens with molecular weights (MW) of 64 kDa [isoelectric point (pI) of 3.5-4.0] and 72 kDa (pI of 4.5) bound to IgG in all patients with endometriosis, but not the controls. Amino acid sequencing of the proteins revealed that they had homology to alpha 2-Heremans Schmidt (HS) glycoprotein (MW: 64 kDa) and transferrin (MW: 72 kDa). Endometriosis patients had significant antibody levels to these two proteins (predictive value of 80-90%). The analysis of patients' endometrial RNA detected the message for alpha 2-HS glycoprotein and transferrin. Albumin (pI 5.5) and collagen (pI 3.5) failed to elicit antibody responses. CONCLUSIONS: Patients with endometriosis have significant antibodies to endometrial transferrin and alpha 2-HS-glycoprotein. We can effectively use an antibody assay using these antigens for diagnosing endometriosis.

Adult↗
PubMed1995

Toxicity of human recombinant interferon-gamma in rats and dogs.

AIM: To study the acute and chronic toxicities of human recombinant interferon-gamma (Hu-rIFN-gamma) in mice, rats, and dogs. METHOD: Twenty mice were administrated Hu-rIFN-gamma (i.m. or i.v.) 4.4 x 10(9) IU m-2 to observe the acute toxicity. In chronic studies, 1 x 10(7), 5 x 10(7), 1 x 10(8) IU m-2 d-1 were given to 80 rats and 5 x 10(5), 5 x 10(7) IU m-2 d-1 were injected to 14 dogs i.m. for 3 months, treatment-related changes were measured in the hematologic, chemical, urinalysis values, ECG and pathologic profile of organs and tissues. RESULTS: The maximal tolerance dose (MTD) i.m. or i.v. in mice was 4.4 x 10(9) IU m-2, 4400 times the recommended clinical dosage (1 x 10(6) IU m-2). No adverse effects were found in chronic toxicity studies. CONCLUSION: Human recombinant interferon-gamma did not produce toxic reaction in rats and dogs.

Animals↗
PubMed1993

Sequential activation of two mitogen activated protein (MAP) kinase isoforms in rat skeletal muscle following insulin injection.

Skeletal muscle is a major target of insulin action. The possible role of MAP kinase activation in insulin receptor signaling in muscle was examined. After a 48-hr fast, rats were injected intravenously with insulin or saline, muscles were excised after 3-20 min, homogenized, and MAP kinases were partially purified by ammonium sulfate precipitation and Mono Q chromatography. Activity was assayed as 32P-incorporation into myelin basic protein. Two activity peaks were identified; peak I eluted with approximately 0.1 M NaCl and peak II with approximately 0.2 M NaCl. Three min after insulin injection the activity of peak II increased > 2-fold, peak I was unchanged. After 10 min, the activity of peak II returned toward baseline, while peak I was activated approximately 3-fold. Immunoblots confirmed the presence of MAP kinases eluting with activity peaks I and II; the former as a approximately 41 kDa protein and the latter as a doublet of approximately 42 and approximately 44 kDa. The data suggest sequential activation of two MAP kinases in muscles; the isoform which activates/deactivates rapidly may represent ERK-1, while the more slowly responding isoform may be ERK-2.

Animals↗
PubMed1992

Kallistatin: a novel human tissue kallikrein inhibitor. Purification, characterization, and reactive center sequence.

A novel human tissue kallikrein inhibitor designated as kallistatin has been purified from plasma to apparent homogeneity by polyethylene glycol fractionation and successive chromatography on heparin-Agarose, DEAE-Sepharose, hydroxylapatite, and phenyl-Superose columns. A purification factor of 4350 was achieved with a yield of approximately 1.35 mg per liter of plasma. The purified inhibitor migrates as a single band with an apparent molecular mass of 58 kDa when analyzed on SDS-polyacrylamide gel electrophoresis under reducing conditions. It is an acidic protein with pI values ranging from 4.6 to 5.2. No immunological cross-reactivity was found by Western blot analyses between kallistatin and other serpins. Kallistatin inhibits human tissue kallikrein's activity toward kininogen and tripeptide substrates. The second-order reaction rate constant (ka) was determined to be 2.6 x 10(4) M-1 s-1 using Pro-Phe-Arg-MCA. The inhibition is accompanied by formation of an equimolar, heat- and SDS-stable complex between tissue kallikrein and kallistatin, and by generation of a small carboxyl-terminal fragment from the inhibitor due to cleavage at the reactive site by tissue kallikrein. Heparin blocks kallistatin's complex formation with tissue kallikrein and abolishes its inhibitory effect on tissue kallikrein's activity. The amino-terminal residue of kallistatin is blocked. Sequence analysis of the carboxyl-terminal fragment generated from kallistatin reveals the reactive center sequence from P1' to P15', which shares sequence similarity with, but is different from known serpins including protein C inhibitor, alpha 1-antitrypsin, and alpha 1-antichymotrypsin. The results show that kallistatin is a new member of the serpin superfamily that inhibits human tissue kallikrein.

Amino Acid Sequence↗
PubMed1992

Inhibition of rat tissue kallikrein gene family members by rat kallikrein-binding protein and alpha 1-proteinase inhibitor.

The regulation of tissue kallikrein activity by plasma serine proteinase inhibitors (serpins) was investigated by measuring the association rate constants of six tissue-kallikrein family members isolated from the rat submandibular gland, with rat kallikrein-binding protein (rKBP) and alpha 1-proteinase inhibitor (alpha 1-PI). Both these serpins inhibited kallikreins rK2, rK7, rK8, rK9 and rK10 with association rate constants in the 10(3)-10(4) M-1.s-1 range, whereas only 'true' tissue kallikrein rK1 was not susceptible to alpha 1-PI. This results in slow inhibition of rK1 by plasma serpins, which could explain why this kallikrein is the only member of the gene family identified so far that induces a transient decrease in blood pressure when injected in minute amounts into the circulation.

Animals↗
PubMed1992

Biochemical characterization and substrate specificity of rat prostate kallikrein (S3): comparison with tissue kallikrein, tonin and T-kininogenase.

A tissue kallikrein-like enzyme encoded by S3 mRNA was purified to homogeneity from rat prostate gland. The apparent molecular mass of the prostate enzyme is 32 kDa as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The intact 32 kDa enzyme is split into two bands of lower molecular mass, 18 and 14 kDa, under reducing conditions on SDS-PAGE. NH2-terminal amino acid sequence analyses of the intact enzyme and heavy and light chains revealed the identity to the translated sequence of a prostate kallikrein cDNA (S3). Isoelectric focusing indicated that the prostate enzyme is a basic protein with pI of 7.30-7.45. Specific activities of the prostate kallikrein toward angiotensin I, angiotensinogen and rat low M(r) kininogen as well as tripeptide chromogenic substrates were compared with those of tissue kallikrein, tonin and T-kininogenase. The kinin-releasing activity is inhibited by leupeptin, antipain, benzamidine and soybean trypsin inhibitor. A sensitive and specific radioimmunoassay for the rat prostate kallikrein shows that the immunoreactive kallikrein levels in prostate and submandibular gland were 23.78 +/- 2.62 micrograms/mg protein (n = 5) and 12.29 +/- 2.25 micrograms/mg protein (n = 5), respectively. The results indicate that the prostate kallikrein S3 is expressed at high levels in both prostate and submandibular glands.

Amino Acid Sequence↗
PubMed1992

[X-ray diffraction studies on tolbutamide solid dispersion].

D860 (tolbutamide) solid dispersions prepared with urea, polyvinyl pyrrolidone (PVP), and polyethylene glycal (PEG) 6000 as carriers were studied by X-ray diffraction, relating to their dissolution rates. D860 in D860-PVP dispersion was shown to be in an amorphous state and to have greater dissolution rate. D860-urea and D860-PEG melts were found to be partly in miscible solid solution state and partly in microcrystal state and possess higher activity and greater dissolution rate. D860-PEG coprecipitate was a physical mixture and its dissolution rate is slower than its melt. No variation in the crystal structure of the D860 dispersions was observed during the ageing test.

Drug Carriers↗
PubMed1992

In vivo catabolism of human kallikrein-binding protein and its complex with tissue kallikrein.

We recently identified and purified a novel human kallikrein-binding protein (HKBP) from human plasma. The HKBP forms a 92 kd sodium dodecyl sulfate-stable and heat-stable complex with tissue kallikrein. This study was undertaken to characterize the plasma clearance and tissue distribution of exogenously administered HKBP and its complex with tissue kallikrein. Human tissue kallikrein was first incubated with purified HKBP, and the high-molecular-weight complex was separated from unbound proteins on a high-pressure liquid chromatography gel filtration column. Tissue kallikrein, kallikrein-binding protein, and their complex were labeled with iodine-125 and then injected intravenously into Sprague-Dawley rats. The disappearance rates of trichloracetic acid-precipitable radioactivity from the circulation were determined. The clearance profile of HKBP shows a nonlinear pattern with an apparent half-life of 65 minutes (n = 4). The plasma clearance of HKBP complexed with kallikrein shows a similar profile but a shorter half-life of 33 minutes (n = 3). HKBP and its complex with kallikrein were mainly taken up by the liver but to a lesser degree by the kidney, lung, and other tissues. Labeled human kallikrein has an apparent half-life of 8 minutes (n = 4), and its clearance consists of a fast and a slow component. The data indicate that kallikrein-HKBP complex is cleared from the circulation two times faster than that of the binding protein alone and that it persists in the circulation four times longer than kallikrein alone. The results support the notion that more than one pathway exists for the metabolism of tissue kallikrein and that HKBP plays a role in modulating tissue kallikrein's bioavailability.

Animals↗
PubMed1990

Multilayer model of photon diffusion in skin.

A diffusion model describing the propagation of photon flux in the epidermal, dermal, and subcutaneous tissue layers of the skin is presented. Assuming that the skin is illuminated by a collimated, finite-aperture source, we develop expressions relating photon flux density within the skin and intensities re-emitted from the skin surface to the optical properties of the individual layers. Model simulations show that the rate at which re-emitted intensities diminish with radial distance away from the source can provide information about absorption and scattering in underlying tissues. Re-emitted intensities measured from homogeneous and two-layer tissue phantoms compare favorably with model predictions. We demonstrate potential applications of the model by estimating the absorption (sigma a) and transport-corrected scattering (sigma's) coefficients of dermis and subcutis from intensities measured from intact skin and by predicting the magnitude of the optical-density variations measured by a photoplethysmograph.

Diffusion↗