Biomedical subjects
Publications and source records attributed to Z Ma.
In this paper are reviewed the research reports on biomaterials used in recent years in the field of tissue engineering for cartilage regeneration. The preparation of these biomaterials are also discussed. Finally, ideas are proposed to solve the problems in the field of cartilage tissue engineering.
OBJECTIVE: To identify the determinants of individual acceptance of voluntary HIV testing and the scope of test results disclosure. METHODS: A cross-sectional study was performed to interview 1 057 subjects aged 15 - 49. RESULTS: Among 653 subjects who had heard of HIV/AIDS, 575 (88.1%) reported willingness to be tested for HIV infection. Of subjects who would accept the offer, 90.2% agreed to disclose testing results to their spouse, 77.1% to other family member, 54.8% to their friends and 50.8% to their neighbors. Logistic regression analysis indicated that the acceptability was associated with being a man, and having better knowledge in HIV/AIDS. CONCLUSIONS: The level of acceptability of voluntary HIV testing is high among people who know about HIV/AIDS. Given the large number of people in rural China who never heard of HIV/AIDS, it is important to carry out information-oriented education activities to increase AIDS awareness among rural residents.
Aventis Pharma (formerly Hoechst Marion Roussel) is investigating the ketolides HMR-3562 and HMR-3787 as potential antibacterial agents. The compounds belong to a series of 2-fluoroketolides. They have exhibited potency against a range of gram-positive bacteria and other respiratory tract pathogens including Haemophilus influenzae in vitro and in vivo.
OBJECTIVE: To inquire into diagnose of congenital malformation of inner ear by CT and MRI. METHOD: To report one case of CT and MRI image of congenital malformation of inner ear, and review relational documents. Character of CT and MRI of inner ear and membranous labyrinth by MR with 3D-CISS sequence were analysed. RESULT: The bone structure of inner ear was shown by CT, the memberanous labyrinth was shown by MRI. CONCLUSION: The mutual benefit of diagnose of congenital malformation of inner ear by CT and MRI. It is important for diagnose of congenital malformation of memberanous labyrinth by MR with 3D-CISS sequence.
In order to establish the immunoassay for insecticides of pyrethroids, hapten (3-phenoxybenzyl-2,2-dimethyleyclopropane-1,3-dicarboxylate) has been synthesized from chrysanthemumcarboxylic acid via chloridization, esterification and oxidation. The structure of the product was determined by IR, 1HNMR and MS analysis.
OBJECTIVE: To determine the carcinogenic potential of reflux juice from patients undergoing remote gastrectomy and to clarify the relationship between duodenogastric reflux and gastric stump cancer. METHODS: A total of 37 reflux juice samples (13 Billroth I, 24 Billroth II) were used. A two-stage transformation assay using BALB/c 3T3 cells was carried out to test the initiating or promoting activity of the samples. RESULTS: 11.1% reflux samples showed initiating activities, whereas 47.4% samples enhanced the MNNG-initiating cell transformation, suggesting that duodenogastric reflux juice might possess tumor-promoter activity (P < 0.05). There was no difference in initiating activities of the samples irrespective of surgical procedures (P > 0.05). Billroth II samples exhibited stronger tumor-promoter activity than Billroth I samples (P < 0.05), in accordance with many epidemic findings that this cancer preferred to Billroth II procedure. The promoter activities were well correlated with the histological changes of the stomas (r(s) = 0.625, P < 0.01), but both their cytotoxicities and initiating activities failed to show this correlation. CONCLUSIONS: The duodenogastric reflux juice from patients undergoing remote gastrectomy has tumor-promoting activity on initiating activity. It is suggested that tumor-promoting potential should be responsible for the high incidence of gastric carcinoma in the patients undergoing remote gastrectomy. Thus a direct evidence for the etiology of gastric stump carcinoma is provided.
The serum amyloid A (SAA) protein is a characteristic and sensitive acute phase reactant in all vertebrates investigated. We molecularly cloned the equine cDNA encoding SAA from the liver of a healthy horse by polymerase chain reaction (PCR). The cloned cDNA is 480 bases in length, and contains an open reading frame (ORF) of 387 nucleotides encoding a precursor SAA protein of 128 amino acids. The precursor of horse SAA seems to have an 18-residue signal peptide and differs from the reported amino acid sequences of the horse SAA by substitution of valine at residue 81. It shows high homology with SAA amino acid sequence of other species such as dog (80.6%), mink (77.5%), human (76.9%) and duck (71.9%). An insertion of eight amino acids at residues between 85 and 92, as compared to human SAA, has also been found in horse SAA. The availability of the equine SAA cDNA will provide a useful reagent for studying its role in diseased horses.
The feasibility of exploiting non-gridded bacterial artificial chromosome (BAC) libraries and some major factors affecting the efficiency of handling such libraries were studied in hexaploid wheat. Even for a bacterial culture containing only 55% recombinants, some 2000 BAC clones with inserts ranging from 45 to 245 kb could be pooled. The pooled BAC clones could be amplified by culturing for up to 6 h without losing any target clones. These results imply that even for hexaploid wheat, which has an extremely large genome, some 250 pools are sufficient for a BAC library that should satisfy many research objectives. This non-gridded strategy would dramatically reduce the cost and make robotic equipment non-essential in exploiting BAC technology. To construct a representative library and to minimise clone competition, thawing and re-freezing ligation mixtures and bacterial cultures should be avoided in BAC library construction and application.
We propose a concept for the rational design and synthesis of highly selective chemotherapeutic agents that makes direct use of genetic information about the disease state. The key idea is to use the mRNA or DNA specific to the disease state to trigger the catalytic release of a cytotoxic drug by promoting the association of a prodrug with a catalyst capable of releasing the drug. We demonstrate the feasibility of such an approach in vitro with a model system that is based on the hydrolysis of p-nitrophenyl esters by imidazole. In our model system, the catalytic component consists of an imidazole group linked to the 5' end of a 15-mer that is complementary to the 5' end of the triggering oligodeoxynucleotide. The corresponding prodrug component consists of a p-nitrophenol ester linked to the 3' end of an 8-mer oligodeoxynucleotide that is complementary to the 3' end of the triggering sequence. We show that this system efficiently releases p-nitrophenol in the presence of all three components and that the reaction is catalytic and undergoes multiple turnovers. We also show that the complex between the catalytic component and the triggering oligodeoxynucleotide behaves like an enzyme and follows Michaelis-Menten kinetics, with a K(M) of 22 microM and a k(cat) of 0.018 min(-1). Most importantly, we show that catalytic release of p-nitrophenol is sensitive to the presence of a single base-pair mismatch.
A novel class of 2-fluoro-6-O-propargyl-11,12-carbamate ketolide derivatives of erythromycin has been synthesized for antibacterial SAR studies. Replacement of the C2-hydrogen by a fluorine atom allows the synthesis of 6-O-propargylic ketones and electron-deficient 6-O-propargylic aromatic derivatives by preventing intramolecular C2-enolate Michael cyclization.
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Upon differentiation, U937 promonocytic cells gain the ability to release a large fraction of arachidonate esterified in phospholipids when stimulated, but the mechanism is unclear. U937 cells express group IV phospholipase A(2) (cPLA(2)), but neither its level nor its phosphorylation state increases upon differentiation. A group VI PLA(2) (iPLA(2)) that is sensitive to a bromoenol lactone inhibitor catalyzes arachidonate hydrolysis from phospholipids in some cells and facilitates arachidonate incorporation into glycerophosphocholine (GPC) lipids in others, but it is not known whether U937 cells express iPLA(2). We confirm that ionophore A23187 induces substantial [(3)H]arachidonate release from differentiated but not control U937 cells, and electrospray ionization mass spectrometric (ESI/MS) analyses indicate that differentiated cells contain a higher proportion of arachidonate-containing GPC species than control cells. U937 cells express iPLA(2) mRNA and activity, but iPLA(2) inhibition impairs neither [(3)H]arachidonate incorporation into nor release from U937 cells. Experiments with phosphatidate phosphohydrolase (PAPH) and phospholipase D (PLD) inhibitors coupled with ESI/MS analyses of PLD-PAPH products indicate that differentiated cells gain the ability to produce diacylglycerol (DAG) via PLD-PAPH. DAG promotes arachidonate release by a mechanism that does not require DAG hydrolysis, is largely independent of protein kinase C, and requires cPLA(2) activity. This may reflect DAG effects on cPLA(2) substrate state.
The effects of different organic solvents (paraffin, organic acid, alcohol and ester) and their volumetric fractions on the cell growth and Taxol production were studied in two-liquid-phase and the two-stage culture. A kinetic model, incorporated the effects of the toxicity of organic solvents was developed for two-liquid-phase culture of Taxus cuspidata in the two-stage Taxol production. The results showed that the proposed kinetic model could fit the experimental data satisfactorily. The results also showed that Taxol production could reach the optimal value when 10-logP was in the range of 2 to 5 and the volumetric fraction of the organic solvents at the corresponding the highest Taxol production should be lower when 10-logP was high.
A series of novel 6-O-substituted erythromycin A derivatives has been synthesized. Good in vitro antibacterial activity has been demonstrated for analogues incorporating a variety of structural features. The methodology disclosed is expected to find application in the design of future macrolide antibiotics that target the prevalent bacterial resistance problem.
Insulin secretion by pancreatic islet beta-cells is impaired in diabetes mellitus, and normal beta-cells are enriched in phospholipids with arachidonate as sn-2 substituent. Such molecules may play structural roles in exocytotic membrane fusion or serve as substrates for phospholipases activated by insulin secretagogues. INS-1 insulinoma cells respond to secretagogues and permit the study of effects of culture with free fatty acids on phospholipid composition and secretion. INS-1 cell glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) lipids are demonstrated here by electrospray ionization mass spectrometry to contain a lower fraction of molecules with arachidonate and a higher fraction with oleate as sn-2 substituent than native islets. Palmitic acid supplementation induces little change in these INS-1 cell lipids, but supplementation with linoleate or arachidonate induces a large rise in the fraction of INS-1 cell GPC species with polyunsaturated sn-2 substituents and a fall in oleate-containing species to yield a GPC profile similar to native islets. The fraction of GPE lipids comprised of plasmenylethanolamine species with polyunsaturated sn-2 substituents in early-passage INS-1 cells is similar to that of islets, but declines on serial passage. Such molecules might participate in exocytotic membrane fusion, and late-passage INS-1 cells have reduced insulin secretory responses. Arachidonate supplementation induces a rise in the fraction of INS-1 cell GPE lipids with polyunsaturated sn-2 substituents and partially restores responses to insulin secretagogues by late-passage INS-1 cells, but does not further amplify secretion by early-passage cells. Effects of extracellular free fatty acids on beta-cell phospholipid composition and secretory responses could be involved in changes in beta-cell function during the period of hyper-free fatty acidemia that precedes diabetes mellitus.
In order to synthesize the artificial antigen methylparathion(M1605), methylparathion was reduced into amino-methylparathion by using acetic acid-zinc powder-hydrochloric acid. Artificial antigens (M1605-BSA, M1605-TTH) were synthesized by conjugating amino-methylparathion to bovine serum albumin(BSA) and tachypleus tridentatus hemocyanin (TTH) directly after diazotization. Rabbits were immunized with M1605-BSA for 10 weeks, and the high titer and high specificity antiserum from those rabbits was testified by double agar gel diffusion and indirect ELISA. The results showed that an artificial antigen was obtained successfully and this made it possible to establish the immunoassay of M1605.
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The non-Hodgkin lymphoma (NHL) subtype anaplastic large-cell lymphoma (ALCL) is frequently associated with a t(2;5)(p23;q35) that results in the fusion of the ubiquitously expressed nucleophosmin (NPM) gene at 5q35 to the anaplastic lymphoma kinase (ALK) gene at 2p23, which is not normally expressed in hematopoietic tissues. Approximately 20% of ALCLs that express ALK do not contain the t(2;5), suggesting that other genetic abnormalities can result in aberrant ALK expression. Here we report the molecular characterization of an alternative genetic means of ALK activation, the inv(2)(p23q35). This recurrent abnormality produces a fusion of the amino-terminus of 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC), a bifunctional homodimeric enzyme that catalyzes the penultimate and final steps of de novo purine nucleotide biosynthesis, with the intracellular portion of the ALK receptor tyrosine kinase. RT-PCR analysis of 5 ALCL tumors that contained the inv(2) revealed identical ATIC-ALK fusion cDNA junctions in all of the cases. Transient expression studies show that the ATIC-ALK fusion transcript directs the synthesis of an approximately 87-kd chimeric protein that is localized to the cytoplasm, in contrast to NPM-ALK, which typically exhibits a cytoplasmic and nuclear subcellular distribution. ATIC-ALK was constitutively tyrosine phosphorylated and could convert the IL-3-dependent murine hematopoietic cell line BaF3 to cytokine-independent growth. Our studies demonstrate an alternative mechanism for ALK involvement in the genesis of NHL and suggest that ATIC-ALK activation results from ATIC-mediated homodimerization. In addition, expected decreases in ATIC enzymatic function in ATIC-ALK-containing lymphomas may render these tumors more sensitive to antifolate drugs such as methotrexate. (Blood. 2000;95:2144-2149)