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Biomedical subjects

Z Jia

Publications and source records attributed to Z Jia.

160 records · Page 9Linked to original sources
PubMed1992

Synthesis and cytotoxic evaluation of some 6-arylidene-2-(alpha-hydroxyamino-alpha-arylmethyl)cyclohexanone oximes and related compounds.

Reaction of 2,6-bis-(phenylmethylene)cyclohexanone (1) with a 4-molar excess of hydroxylamine hydrochloride and sodium acetate to produce the corresponding oxime 2 gave rise to 2-(alpha-hydroxyamino-alpha-phenylmethyl)-6-phenylmethylenecyclohexan one oxime (5a), whose structure was deduced from high-resolution proton nuclear magnetic resonance spectroscopy and confirmed by X-ray analysis. Compound 2 was eventually prepared from 1 with hydroxylamine per se and not with a mixture of hydroxylamine hydrochloride and sodium acetate. Ten analogues of 5a, namely 5b-5k, were prepared and evaluated for cytotoxicity. Six of the 11 compounds in series 5, as well as 1, showed activity in the 240-950 microM range against murine mammary EMT6 cells. Series 5 was also examined for cytotoxicity in an in vitro screen conducted by the National Cancer Institute with approximately 54 cell lines, and four compounds demonstrated selective toxicity toward various groups of tumors.

Animals↗
PubMed1992

Evaluation of cytotoxicity of some Mannich bases of various aryl and arylidene ketones and their corresponding arylhydrazones.

Mannich bases were synthesized and converted to the corresponding arylhydrazones. X-ray analysis of a ketone (1a) and a hydrazone (4d) revealed structural features of interest. All of the compounds showed cytotoxicity toward murine lymphocytic leukemia L1210 cells in the 4.9-25.0-microM range. The correlation coefficients generated by plotting the IC50 values (the concentrations of compounds that inhibit the growth of tumors by 50%) of some hydrazones against certain electronic, hydrophobic, and steric constants of the aryl substituents indicated only weak correlations. A few ketones and hydrazones displayed significant cytotoxicity to the WiDr human colon cancer cells, and these derivatives, especially the ketones, may serve as prototypes for future drug development. The KB tumor (a human epidermoid carcinoma of the nasopharynx) was somewhat refractory to selected compounds. In an in vitro assay conducted by the National Cancer Institute and involving approximately 53 tumor cell lines originating from eight neoplastic diseases, 65% of the compounds showed some selectivity toward one or more groups of cancers, principally leukemia, melanoma, and colon cancer. The bioevaluation of the ketones and hydrazones against the L1210, WiDr, and KB tumors, as well as evidence from proton nuclear magnetic resonance studies did not support the suggestion that hydrazones may be prodrugs of the corresponding ketones.

Animals↗
PubMed1992

Transplantation of an island fascial flap with a vascular pedicle for arthoplasty of the hip.

Intra-articular transplantation of a vascularised island fascial flap has been used for arthroplasty of the hip in 18 patients with an average age of 22 years. They have been followed up for an average of 3 years; 14 were graded excellent and 4 good using the criteria of Charnley and Wu Zhikang. The procedure has a place in the treatment of hip disease in the younger patient.

Adolescent↗
PubMed1992

New Eremophilane Type Lactones from the Roots of Ligularia veitchiana.

Phytochemical investigation of the roots of LIGULARIA VEITCHIANA has resulted in the characterization of two new eremophilanolides together with beta-sitosterol, stigmasterol, taraxol, and liguhodgsonal whose structure was further confirmed by the (13)C-NMR techniques. The structures of the new constituents were elucidated by spectroscopic methods and shown to be 1beta, 10beta-epoxy-6beta(2'-hydroxymethylacryloyloxy)-8beta-hydroxy-eremophila-7(11)-en-12,8alpha-olide ( 1) and 1beta, 10beta-epoxy-6beta-(2'-hydroxymethylacryloyloxy)-8beta-ethoxy-eremophila-7(11)-en-12,8alpha-olide ( 2).

Journal Article↗
PubMed1992

Eudesmanolides and Other Constituents from Artemisia argyi.

The phytochemical investigation of the aerial parts of ARTEMISIA ARGYI afforded beta-sitosterol, stigmasterol, alpha-amyrin, beta-amyrin, friedelin, naringenin, quercetin, and four eudesmane derivatives, two of which were new eudesmanolides. The structures of the novel compounds were elucidated by high field NMR techniques.

Journal Article↗
PubMed1991

New Diterpenoids from Euphorbia sieboldiana.

From the acetone extract of roots of EUPHORBIA SIEBOLDIANA, three known diterpenes, ENT-atisane-3beta,16alpha,17-triol ( 1), ingenol ( 4), and helioscopinolide A ( 5) as well as two new diterpenes, 3beta- O-acetyl- ENT-atisane-16alpha,17-diol ( 2), and ingenol-20-palmitate ( 3) were isolated. Their structures were elucidated by spectroscopic methods and chemical transformations.

Journal Article↗
PubMed1990

New Taxanes from Taxus chinensis.

Two new taxane diterpenes, decinnamoyltaxagifine ( 3) and decinnanioyltaxagifine acetate ( 2), have been isolated from the leaves and stems of TAXUS CHINENSIS. Their structures were elucidated by spectroscopic methods. Their (13)C-NMR chemical shifts were assigned.

Journal Article↗
PubMed1990

3,5-Bis-benzylidene-4-piperidones and related compounds with high activity towards P388 leukemia cells.

3,5-Bis(benzylidene)-4-piperidones and related compounds were prepared and found to have between 100 and 9700 times the activity of N,N'-bis(2-chloroethyl)-N-nitrosourea towards P388 leukemia cells. The shapes of six of these molecules--determined by X-ray crystallography--were compared, but no correlation between the stereochemistry of the molecules or their electronic properties and cytotoxicity was apparent. Molecular modification of the compounds by forming two mono-benzylidene compounds, a related acyclic derivative and an N-acyl compound resulted in diminished but retained high cytotoxicity. Two representative compounds lowered glutathione levels of liver following their intraperitoneal injection into mice. Two quaternary ammonium compounds were shown to bind in the minor groove of DNA, while four related non-quaternary ammonium derivatives did not demonstrate this property. We conclude that the modes of action of these highly cytotoxic compounds include alkylation of cellular thiols and DNA binding, but interference with other biochemical processes is also probably involved.

Animals↗
PubMed1990

[Processing technique of American ginseng].

The article deals with a new technique for processing American ginseng cultivated in China by far-infrared and moisture absorption. The qualities of processed product as per ton-quantity (including appearance, physical properties and chemical compositions) show no difference from those of American ginseng imported from U.S.A. and Canada. The mathematical model of dry-loss weight of American ginseng during processing is given in this article.

Amino Acids↗
PubMedDate not supplied

Structural comparison of the histidine-containing phosphocarrier protein HPr.

The phosphocarrier protein HPr is a central component of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) that is responsible for carbohydrate uptake in many bacterial species. A number of three-dimensional structures of HPrs from both Gram-positive and Gram-negative bacteria have been determined; the overall folding topology of HPr is an open-faced beta-sandwich composed of three alpha-helices and a beta-sheet. A detailed structural comparison of these HPrs has been carried out. Besides the overall main chain folding, many detailed structural features are well conserved in all HPr structures. The three x-ray structures of HPrs from Escherichia coli, Streptococcus faecalis, and Bacillus subtilis show considerable overall similarity with respect to the positions of the C alpha atoms. A significant structural difference between HPrs from Gram-positive and Gram-negative bacteria is found in the region of Gly54, owing to the steric effects of Tyr37 in HPrs from the Gram-positive species. The region around Gly54 is involved in the binding of HPr to other PTS proteins and the differences in this region may be responsible for some of the poor functional complementation between HPrs from Gram-positive and Gram-negative species. The active center region, residues 12-18, appears to have significant differences in the comparisons between the overall structures. These differences support the proposal that phosphorylation and dephosphorylation of the active site His15 is accompanied by conformational changes. However, a local structural comparison of residues 12-18 from the x-ray structures of HPrs from E. coli and B. subtilis, and the two-dimensional nuclear magnetic resonance structure of B. subtilis HPr suggests that there is a conserved active center involving residues His15, Arg 17, and Pro18, which shows little conformational change during the phosphorylation cycle. The results of other experimental approaches, including site-directed mutagenesis and NMR spectroscopy, are in some cases difficult to rationalize with some of the details of the structures, but do appear to favour the conclusion that little conformational change occurs.

Amino Acid Sequence↗
PubMedDate not supplied

Selective abolition of the NMDA component of long-term potentiation in mice lacking mGluR5.

The mechanisms underlying the differential expression of long-term potentiation (LTP) by AMPA and NMDA receptors, are unknown, but could involve G-protein-linked metabotropic glutamate receptors. To investigate this hypothesis we created mutant mice that expressed no metabotropic glutamate receptor 5 (mGluR5), but showed normal development. In an earlier study of these mice we analyzed field-excitatory postsynaptic potential (fEPSPs) in CA1 region of the hippocampus and found a small decrease; possibly arising from changes in the NMDAR-mediated component of synaptic transmission. In the present study we used whole-cell patch clamp recordings of evoked excitatory postsynaptic currents (EPSCs) in CA1 pyramidal neurons to identify the AMPAR- and NMDAR-mediated components of LTP. Recordings from control mice following tetanus, or agonist application (IS, 3R-1-amino-cyclopentane 1,3-dicarboxylic acid) (ACPD), revealed equal enhancement of the AMPA and NMDA receptor-mediated components. In contrast, CA1 neurons from mGluR5-deficient mice showed a complete loss of the NMDA-receptor-mediated component of LTP (LTP(NMDA)), but normal LTP of the AMPA-receptor-mediated component (LTP(AMPA)). This selective loss of LTP(NMDA) was seen in three different genotypic backgrounds and was apparent at all holding potentials (-70 mV to +20 mV). Furthermore, the LTP(NMDA) deficit in mGluR5 mutant mice could be rescued by stimulating protein kinase C (PKC) with 4beta-phorbol-12,13-dibutyrate (PDBu). These results suggest that PKC may couple the postsynaptic mGluR5 to the NMDA-receptor potentiation during LTP, and that this signaling mechanism is distinct from LTP(AMPA). Differential enhancement of AMPAR and NMDA receptors by mGluR5 also supports a postsynaptic locus for LTP.

Animals↗