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Biomedical subjects

Z Tian

Publications and source records attributed to Z Tian.

At least 73 records · Page 4Linked to original sources
PubMed1997

Chemical modification and structure-activity relationships of pyripyropenes. 3. Synthetic conversion of pyridine-pyrone moiety

Structure-activity relationships of the pyridine-pyrone moiety in pyripyropene A (1), a potent acyl-CoA : cholesterol acyltransferase (ACAT) inhibitor of fungal origin, were studied. Several kinds of aromatic or hetero ring substituents for the pyridine moiety were synthesized using unique degradation reaction, following by gamma-acylation. All the six synthesized analogs decreased the inhibitory activity with 20 to 200 times larger IC50 values than that of 1. Furthermore, the pyridine-pyrone substituent also dramatically decrease the inhibitory activity. Thus, the pyridine-pyrone moiety is important for eliciting potent ACAT inhibition.

Journal Article↗
PubMed1997

[Blocking action of tetrandrine on the cell proliferation induced by PDGF in human lung fibroblasts and liver Ito cell of rats].

OBJECTIVE: To investigate the mechanism of hepatic fiberosis, the effects of platelet-derived growth factor (PDGF) on cell proliferation activity and collagen synthesis in human lung fibroblasts (HLF) and Ito cells of rat liver as well as the blocking action of tetrandrine on the cell proliferation induced by PDGF. METHODS: The Ito cells were separated from liver of rats by using the perfusion of collagenase and density pradient centrifugation. The cell proliferation was observed with the incorporation method of H-TdR and 3H-L-proline. RESULTS: Under condition of cell culture with 1% serum, PDGF could significantly enhance DNA synthesis, cell proliferation and collagen synthesis, which increased in degree with a rising of concentration of PDGF. This occurred in culture without serum, but under the same condition, if PDGF was applied together with insulin-like growth factor (IGF), it enhanced cell proliferation. The result also showed that the dose of tetrandrine below the level of inhibiting cell DNA synthesis could antagonize the stimulation action of PDGF on cell proliferation and collagen synthesis. CONCLUSION: Tetrandrine plays the blocking action in the promoting cell proliferation induced by PDGF.

Alkaloids↗
PubMed1997

[Activating blood circulation and removing stasis in treating polycythemia vera: clinical observation and therapeutical mechanism].

OBJECTIVE: To assess the efficacy of "method of activating blood circulation and removing stasis (ABCRS)" in treating polycythemia vera. METHODS: 28 cases of polycythemia vera were treated with ABCRS and observed with bone marrow colonies. RESULTS: 15 casses were responsibe, of them 4 cases reached clinical remission, 11 cases were improved. Both bone marrow colonies of colony forming unit-erythroid dependent of erythropoietin (EPO + CFU-E) and colonies of CFU-E independent of EPO. (EPO-CFU-E) from these cases decreased significantly, especially the latter. ABCRS mainly suppressed the proliferation and differentiation of EPO-CFU-E. In addition, bone marrow colonies of colony formng unit-fibroblastoids (CFU-F) from these cases also changed obviously. CONCLUSION: ABCRS is effective in treating polycythemia vera.

Adult↗
PubMed1996

Renal angiomyolipoma: diagnosis with B-ultrasonography, CT scanning, DSA and its interventional treatment.

From 1989, 15 cases of renal angiomyolipoma (AML) have been diagnosed by ultrasonography. CT scanning and digital subtraction angiography (DSA) at our hospital. In 8 patients with uneven hyperechoes on B-mode ultrasonography (B-US) (8/15) and 7 with low density of fat on CT scanning (7/12) accurate diagnosis was established preoperatively. DSA revealed the "berry-like" pseudoaneurysms in the arterial phase (14 cases), the defined lucent area in the nephrogram phase (10 cases) and the "onion-peel appearances" during venous phases (8 cases), correct diagnosis was achieved in all patients. 8 cases were surgically treated and 7 treated by subselective embolization of renal artery. Effects in all cases were good. The diagnostic value of B-US, CT scanning, DSA and interventional treatment of AML was discussed. It was believed that the diagnosis with DSA was a technique with high specificity, and embolization therapy was simple and effective for AML.

Adult↗
PubMed1996

Chemical modification and structure-activity relationships of pyripyropenes. 1. Modification at the four hydroxyl groups.

Four hydroxyl groups of pyripyropenes have been modified and evaluated for their ability to inhibit microsomal acyl-CoA:cholesterol acyltransferase (ACAT) activity in vitro and to lower cholesterol absorption in vivo in a cholesterol-fed hamster. 7-O-n-Valeryl derivative (8c) improved the in vitro ACAT inhibitory activity (IC50 = 13 nM) about 7 times better than pyripyropene A. Introduction of methanesulfonyl group at 11-hydroxyl group (17a) increased both in vitro activity (IC50 = 19 nM) and in vivo efficacy (ED50 = 10 mg/kg).

Animals↗
PubMed1996

Stereotactic intratumour irradiation with nuclide for craniopharyngiomas.

OBJECTIVE: Craniopharyngiomas is a kind of intractable tumor in neurosurgery. Since the radical excision is very difficult and occasionally hazardous because of its deep location and close neighbouring to critical cerebral structures, it is necessary to look for a simple and effective method. PATIENTS AND METHODS: Stereotactic intratumour irradiation with instillation of nuclide colloid was performed in 220 patients with craniopharyngiomas (altogether 265 times), of whom, 130 were male and 90 female. Their ages ranged from 5 to 69 years. The syndromes of optic path's impairment were present in all of the patients. CT or MRI scan showed cystic tumour in 125 patients, solid and cystic in 80 and solid in 15. No severe complications and death were related to the operation. RESULTS: 150 patients were followed up for 2 months to 7 years (average 3.5 years). Tumours disappeared in 92 patients (61.4%), decreased dramatically in 20 (13.4%), decreased less than 50% in 19 (12.6%), and increased in 15 (10%); and there were 4 deaths (2.6%). CONCLUSIONS: Stereotactic intratumour irradiation with instillation of nuclide colloid is effective in the patients with craniopharyngiomas. Beta-emitting isotopes (P-32 and Y-90) are the preferred internal radiation source because of their limited penetration of the energy released and the greater ease of handling. A calculated dose of 20 000 rads to the cyst wall is recommended.

Adolescent↗
PubMed1996

Enzyme immunoassay of two nicergoline metabolites, 10 alpha-methoxy-9, 10-dihydrolysergol (MDL) and 1-methyl-10 alpha-methoxy-9, 10-dihydrolysergol (MMDL).

Specific and sensitive enzyme immunoassays for two nicergoline metabolites, 10 alpha-methoxy-9, 10-dihydrolysergol (MDL) and 1-methyl-10 alpha-methoxy-9, 10-dihydrolysergol (MMDL) have been developed. The hydroxyl group of hydroxymethyl at position 8 of either MDL or MMDL was carboxymethylated to introduce a carboxyl group for protein conjugation. Antibodies generated from O-carboxymethyl MDL or MMDL recognized the spacer arm between the hapten and the carrier protein and the molecular domain near the conjugation site as well. A heterologous bridge strategy was used to improve the affinity of the hapten-enzyme conjugate to the antibodies. The sensitivity of both assays was greatly increased by using such an approach. Both antibodies are specific for their own haptens. Little cross reactivity was observed with nicergoline and other metabolites. Determination of MDL and MMDL from both spiked plasma and urine showed nearly quantitative recovery. Detection of MDL and MMDL can be as sensitive as 10 pg/ml.

Animals↗
PubMed1996

[Stereotactic intratumoral irradiation of huge craniopharyngioma].

Craniopharyngioma, often with cystic diliatation, is difficult to resect radically. Fifty patients with huge craniopharyngioma (diameter of tumor was over 5 cm) treated with intratumoral irradiation of radioactive isotopes (32P and 90Y) through CT-guided Leksell stereotactic system are reported. The patients were 2 to 69 years of age with the disease of 1- to 12-year duration. Of the 50 patients, 21 had recurrent tumor after craniotomy, 29 without surgery operation before. All tumors were confirmed pathologically. The major clinical symptoms were as follows: visual field defect, headache, vomiting, diabetes insipidus, hemiplegia and growth retardation in juvenile cases. There was no death or serious complications following the treatment procedure. Partial response (> 50% reduction of tumor size on CT scanning with improvement of symptoms and signs) rate of the treatment was 82.0% at one month and 62.0% at 2 to 7 years after treatment.

Adolescent↗
PubMed1995

Determination of a cyclic guanine monophosphate phosphodiesterase inhibitor (SCH 51866) in rat serum using capillary zone electrophoresis.

A capillary zone electrophoretic (CZE) assay was developed for the determination of cis-5,6a,7,8,9,9a-hexahydro-2-[4-(trifluoromethyl)phenylmethyl]-5-methyl - cyclopent[4,5]imidazo[2,1-b]purin-4(3H)-one, SCH 51866 (I), a cyclic guanine monophosphate phosphodiesterase inhibitor, in rat serum using acetonitrile deproteination as a clean-up step before injection. The calibration curve was linear over a serum concentration range of 0.5 to 10 micrograms/ml serum with a correlation coefficient (r) > 0.99. The limit of quantitation (LOQ) was established at 0.5 micrograms/ml. Fifty microliters of serum were used for analysis, which allowed serial bleeding (8 samples) from a single rat to characterize the pharmacokinetic profile of I after either oral or intravenous drug administration. In traditional pharmacokinetic and toxicokinetic studies in rodents, one animal provides only one serum sample since 1 to 2 ml of sample volume is required for chromatographic analysis, resulting in the use of a large number of animals per study. This assay yields a significant reduction in the use of animals, hence providing a large reduction in resources and time in drug discovery and development.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1995

A specific enzyme immunoassay (EIA) with selective extraction for quantitation of a topical anti-inflammatory agent, SCH 40120, in human plasma.

SCH 40120 is a potent anti-inflammatory agent under development for the topical treatment of dermal inflammatory and allergic disorders such as atopic dermatitis, contact dermatitis and psoriasis. We have previously described a sensitive enzyme immunoassay (EIA) for SCH 40120 in unextracted human plasma to support clinical studies. However, severe cross-reaction with unknown metabolites was observed during validation using samples from rats dosed with 14C-SCH 40120. Therefore, a selective extraction procedure was developed to remove the unknown plasma metabolites of SCH 40120 prior to EIA quantitation. The modified EIA using extracted plasma was cross-validated with an LC method using plasma samples from dosed subjects (human and rat), thereby confirming the specificity of the assay. The EIA can reliably quantitate SCH 40120 in plasma samples from 100 pg ml-1 to 10 ng ml-1 with good linearity, accuracy and precision, and is suitable for pharmacokinetic studies in man.

Administration, Topical↗
PubMed1995

Multiple subpial transection for treatment of intractable epilepsy.

On the basis of experimental study, we applied multiple subpial transection (MST) to treat 50 patients with intractable epilepsy in which epileptigenic lesion involved functional areas such as pericentral gyrus, postcentral gyrus, Broca's area, Wernicke's area, visual cortex, etc. They were followed up for 6 to 40 months. Complete control of seizures was obtained in 32 patients, significant reduction of seizure (more than 50%) in 13, reduction (less than 50%) in 3, and no effect in 2. The total effective rate was 96%. No functional defect was found in all patients. The mechanism of the disease and surgical technique were discussed in detail. We consider that MST could replace some standard excisional therapy for local epilepsy.

Adolescent↗
PubMed1995

[Epidemiologic studies on three episodes of acute bacillary dysentery outbreak].

Three episodes of illness outbreak, with major symptoms of acute abdominal pain and diarrhea, occurred in 1990 to 1991 in the army forces stationed in Beijing. Bacillary dysentery outbreak caused by Shigella dysentariae were confirmed with epidemiological investigations and pathogen identification. Drug sensitivity tests with Kirby-Bauer method for the strain isolated showed it had obvious resistance to 13 of 14 kinds of antibiotics tested. Detection of plasmid with Birnboim method showed most of the strains had R-plasmid of 120-140 Md and few had small plasmid. It suggested inherent connection between drug-resistance of the strains and plasmid.

China↗
PubMed1995

[Morphological and histological studies of the Chinese drug lao-guan-cao].

Lao-guan-cao has long been used in Chinese traditional medicine. It is used as an antirheumatic and circulation promoting drug for the treatment of acute and chronic rheumatalgia; also used as a detoxicant for enteritis and bacillary dysentery. The dried aerial parts of Erodium stephanianum Willd. and Geranium wilfordii Maxim. (family Geraniaceae) have been specified in the Chinese Pharmacopoeia (1990 ed.) According to the literature and the authors' market investigations, the commercial drug Lao-guan-cao chiefly consists of the aerial parts of Erodium stephanianum Willd. Also those rather popularly used in several provinces are the aerial parts of Geranium nepalense Sweet and G. sibiricum L. In this paper, the morphological and histological characters of the crude drugs derived from E. stephanianum Willd., G.nepalense Sweet and G.sibiricum L. are described. It is found that the following characters are useful for distinguishing the drugs derived from the above mentioned three species. (1) The shape and size of leaf; (2) the number and arrangement of the vascular bundles of stem; (3) the number of the vascular bundles in midrib and layers of palisade cells of leaf; (4) the presence or absence of stomata in upper epidermis; (5) the characters of cells containing crystals in sepal; (6) the characters of epidermis cells, cells containing crystals and fibers of pericarp; (7) the types of hairs and glandular hairs on epidermis of stem, leaf, sepal and pericarp; (8) the characters of anticlinal walls of epidermal cells of seed coat.

Drugs, Chinese Herbal↗
PubMed1995

[Karyological studies on the fruit of Gardenia jasminoides Ellis].

This paper reports the karyological studies on the fruit of Gardenia jasminoides and G. jasminoides var. grandiflora. The chromosome numbers are 2n = 22 and the places of centromere are metacentric and submedian. The fruit of G. jarminoides is more primary than Gardenia jarminoidce var. grandiflora in karyotype.

Centromere↗
PubMed1994

Effects of C alpha-methyl substitution on the conformation of linear GnRH antagonist analogs.

We have examined the effect of C alpha-methyl groups on the conformational ensemble of GnRH analog peptides by comparing 1H 2D NMR data from two analogs, Ac-D-Nal1-D-4-Cl-C alpha-Me-Phe2-D-Pal3-Ser4-Tyr5-D-Arg6-Leu7-Arg8-Pro9-D-Al a10- NH2 (1) and Ac-D-Nal1-D-4-Cl-C alpha-Me-Phe2-D-Pal3-Ser4-C alpha-Me-Tyr5-D-Arg6- Leu7-C alpha-Me-Arg8-Pro9-D-Ala10-NH2 (2). The two additional C alpha-methyl groups in residues 5 and 8 of 2 do not influence significantly the pattern of the observable main chain NOE intensities, or of the backbone HN proton chemical shifts, which indicates that they do not produce global changes in the conformational ensemble of the peptide. A local change induced by the substitution was observed in the conformation at D-Arg8-Pro9.

Amino Acid Sequence↗
PubMed1994

[Studies on the constituents of the roots of Acorus calamus L].

A new tricyclic sesquiterpene, named calamenone (1), and two known sesquiterpenes, calamendiol (2) and isocalamendiol (3), were isolated from the roots of Acorus calamus L. The structure of the new compound was elucidated on the basis of spectral and X-ray diffraction data.

Drugs, Chinese Herbal↗
PubMed1993

Amino- and guanidinoacylryanodines: basic ryanodine esters with enhanced affinity for the sarcoplasmic reticulum Ca(2+)-release channel.

Amino- and guanidinoacyl esters of ryanodine were prepared to evaluate the effect of basicity on the binding affinity of these derivatives for the sarcoplasmic reticulum Ca(2+)-release channel (SR CRC). In the presence of DCC and DMAP Cbz-beta-alanine reacts with ryanodine in CH2Cl2 to give O10eq-Cbz-beta-alanylryanodine (3a), which on hydrogenolysis yields the beta-alanyl ester (4a). N,N'-bis-Cbz-S-methylthiourea reacts with 4a to yield beta-N,N'-bis-Cbz-guanidinopropionylryanodine (5a). O10eq-beta-guanidinopropionylryanodine (6a) is obtained on hydrogenolytic deprotection of 5a. The binding affinity of beta-alanine ester (4a) and its glycyl congener (4b) is 2-3-fold greater, and that of the beta-guanidinopropionyl ester (6a) and its acetyl congener (6b) 3-6-fold greater, than that of ryanodine. The effect of ryanodine on SR Ca2+ flux is of a biphasic nature: nanomolar levels open (activate) the channel, while micromolar levels close (deactivate) it. The base-substituted esters 4a and 6a both display a unidirectional effect: they only open the channel. An understanding of ryanodine's mode of action and the design of effective SR CRC activating and deactivating ryanoids for possible therapeutic application are major research objectives.

Amino Acids↗