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Biomedical subjects

Q Yao

Publications and source records attributed to Q Yao.

83 records · Page 5Linked to original sources
PubMed1994

[A study of DNA damage induced by asbestos fibers in vitro].

The results of our in vitro study showed that Rhodesia chrysotile, X. K. chrysotile, UICC chrysotile, crocidolite and amosite could cause damage to calf thymus DNA by inducing the production of 8-hydroxy-2'-deoxyguanosine (8-OH-dG). After adding H2O2 and/or FeSO4, the production of 8-OH-dG, induced by asbestos fibers was significantly increased. The fiber of UICC crocidolite has the most untoward effect, that of UICC amosite comes next, and the three chrysotile fibers are the weakest ones. The effect of asbestos fibers on the production of 8-OH-dG has some relationship with hydroxy free radical and the type of asbestos. It is suggested that asbestos fibers could induce DNA point mutation through A.T and G.C transversion by the production of 8-OH-dG, which is related with the carcinogenesis of asbestos.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1993

Tb(III) and Eu(III) as fluorescent probes to investigate the metal-binding sites of trichosanthin.

Tb(III) and Eu(III) ions were used as fluorescent probes in the study of the trichosanthin (TCS). The fluorescence of Tb(III) was increased considerably when bound to TCS to replace the Ca(II) ions. The nonradiative energy transfer from fluorescent tryptophan (Trp) residues to the bound Tb(III) or Eu(III) took place. From a Foster d-d nonradiative energy transfer mechanism, it was obtained that the average distance between the bound Tb(III) and the Trp residue is 1.27nm. The results indicate that the major groups in TCS bound to Ca(II) ions should be the carboxylic side groups of the glutamic acid and/or aspartic acid. The fluorescent quenching of Ca(II)-free TCS by adding Tb(III) or Eu(III) into TCS from which the Ca(II) ions had been removed was discussed as well.

Binding Sites↗
PubMed1993

Long-term reversal of diabetes by the injection of immunoprotected islets.

The intraperitoneal injection of insulin-producing islets immunoprotected by an alginate-poly(amino acid) membrane is a potential method of reversing diabetes without the need for lifelong immunosuppression. Previous attempts to demonstrate this technology in large animals have failed, preventing application in humans. We have determined that key factors responsible for these past failures include cytokine (interleukins 1 and 6 and tumor necrosis factor) stimulation by mannuronic acid monomers from alginate capsules with weak mechanical integrity, which results in fibroblast proliferation. With this insight, we formulated mechanically stable microcapsules by using alginate high in guluronic acid content and report prolonged reversal of diabetes in the spontaneous diabetic dog model by the intraperitoneal injection of encapsulated canine islet allografts. Euglycemia, independent of any exogenous insulin requirement, was noted for up to 172 days. Graft survival, evidenced by positive C-peptide release, was noted for as long as 726 days in a recipient receiving a single injection of immunoprotected islets. Histological evidence of viable islets retrieved from the peritoneal cavity 6 months posttransplant confirmed the biocompatibility and immunoprotective nature of this capsule formulation. The finding that intraperitoneal injection of alginate-immunoprotected islets, a minimally invasive surgical procedure, is effective in prolonged (> 1 year) maintenance of glycemic control, without the need for lifelong immunosuppression, may have significant implications for the future therapy of type I diabetes in humans.

Alginates↗
PubMed1991

[Screening studies on anti-inflammatory function of traditional Chinese herb Gardenia jasminoides Ellis and its possibility in treating soft tissue injuries in animals].

This paper reports the study of six fractions and one chemical constituent isolated from the traditional Chinese herb Gardenia jasminoides. The results showed that two fractions (G5.G6,), alcohol extract (G1) and genipoiside(A) had obvious anti-inflammatory effects and were comparatively effective in treating soft tissue injuries in animals.

Animals↗
PubMed1991

[Microwave processing method of semen Armeniacae Amarum].

This paper reports the microwave processing method of Semen Armeniacae Amarum (Prunus armeniaca var. ansu). The experimental results showed that amygdalase was completely inactivated and the contents of amygdaloside were not reduced at all. The time and temperature of the processing method have also been studied.

Amygdalin↗
PubMedDate not supplied

Play the winner for phase II/III clinical trials.

In comparing two treatments under a typical sequential clinical trial setting, a 50-50 randomization design generates reliable data for making efficient inferences about the treatment difference for the benefit of patients in the general population. However, if the treatment difference is large and the endpoint of the study is potentially fatal, it does not seem appropriate to sacrifice a large number of study patients who are assigned to the inferior arm. An adaptive design is a data-dependent treatment allocation rule that sequentially uses accumulating information about the treatment difference during the trial to modify the allocation rule for new study patients. In this article, we utilize real trials from AIDS and cancer to illustrate the advantage of using adaptive designs. Specifically we show that, with adaptive designs, the loss of power for testing the equality of two treatments is negligible. Moreover, the study patients do not have to pay a handsome price for the benefit of future patients. We also propose multi-stage adaptive rules to relax the administrative burden of implementing the study and to handle continuous response variables, such as the failure time in survival analysis.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Adenoviral mediated delivery of FAS ligand to arthritic joints causes extensive apoptosis in the synovial lining.

BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune disease where the synovial lining layer of the joint becomes thickened, hypercellular, and highly aggressive. Invading synovial tissue erodes cartilage and subchondral bone and leads to loss of joint function. FasL, a cell-surface molecule on activated T-cells interacts with its receptor, Fas, to induce apoptosis in target cells. We addressed the feasibility of using adenoviral gene transfer of FasL therapeutically to mediate apoptosis in arthritic joints similar in size to the small joints of the hands and feet that are the primary sites of RA in humans. METHODS: Adenoviral vectors were used to transfer FasL and LacZ cDNAs into human RA and rabbit synovial fibroblasts in culture where apoptosis was evaluated using MTT and TUNEL analyses. The ability of Ad.FasL to mediate synovial apoptosis in vivo was then addressed in an IL-1-induced arthritis model in the rabbit knee. RESULTS: In culture, delivery of FasL was found to efficiently induce apoptosis in both human RA and rabbit synovial fibroblasts. The ability of Ad.FasL to induce synovial apoptosis was then evaluated in rabbit knee joints. 24 h after intra-articular injection of 10(11) Ad.FasL particles, large regions of synovial tissue were observed histologically consisting primarily of fibrous matrix and cellular debris. TUNEL staining of corresponding sections was highly positive for fragmented DNA. Glycosaminoglycan (GAG) synthesis from cartilage shavings from treated joints suggests that Ad.FasL does not induce significant apoptosis in resident articular chondrocytes. CONCLUSIONS: Infection of human and rabbit synovial fibroblasts with Ad.FasL results in significant apoptotic cell death in vitro. Direct intra-articular injection of Ad.FasL in the arthritic rabbit knee results in extensive apoptosis in the synovium without affecting chondrocyte viability.

Adenoviridae↗
PubMedDate not supplied

Fluorescence spectroscopic study of the interaction of saporin with phospholipid vesicles.

Saporin-S6 (SO-6) is a type-1 ribosome-inactivating protein purified from the seeds of Saponaria officinalis. The fluorescence characteristics of SO-6 were studied in the presence and absence of phospholipids. The interaction of SO-6 with DMPG or DMPC vesicles results in a decrease in the fluorescence emission intensity of tryptophan without any shift in the emission maximal wavelength. The results of fluorescence titration indicate that DMPG/SO-6 saturation molar ratio is 100: 1, but the binding of DMPC with SO-6 does not reach a saturating plot. A shielding of the tryptophan fluorescence from quenching by acrylamide on interaction with the phospholipids was observed, and this shielding was more pronounced in the presence of DMPG. The interaction of SO-6 with DMPG vesicles is stronger in the liquid-crystalline phase than in the gel phase. Extrinsic fluorescence studies indicated that the interaction of the protein with DMPG vesicles does not modify the phase transition temperature of the lipid, but decreases the amplitude of the change of fluorescence anisotropy associated with the co-operative melting of 1,6-diphenyl-1,3,5-hexatriene (DPH)-labelled vesicles. These results indicate that both electrostatic and hydrophobic components are involved in the SO-6-lipid vesicle interaction.

Acrylamide↗
PubMedDate not supplied

Glucose-insulin kinetics of the extravascular bioartificial pancreas. A study using microencapsulated rat islets.

The success of the extravascular bioartificial pancreas (BAP) is contingent on the rapid transfer of the glycemic signal across both an extravascular compartment and a semipermeable membrane and of insulin from the BAP to the recipient. To examine the possibility of microencapsulated islets such as the BAP to achieve satisfactory in vivo glucose-insulin kinetics, islets were isolated from Lewis rats, encapsulated in poly-L-lysine-alginate membranes, and isogenically transplanted into the peritoneal cavity of 14 streptozotocin induced diabetic rats. Fasting blood glucose (BG) was measured and intravenous glucose tolerance was tested at 8-10 weeks and compared with three control groups: 1) normal Lewis rats (n = 6); 2) untreated diabetic rats (n = 5); and 3) diabetic rats that received intraperitoneal implants of empty capsules (n = 4). Ten animals that received microencapsulated islets (5,271 +/- 431) promptly became normoglycemic, with a mean BG of 128 +/- 17 ng/dl 3 days after transplantation and maintained this level > 100 days. Intravenous glucose tolerance K-value for the group was 3.84 +/- 0.32 compared with 3.96 +/- 0.39 (p = 0.83) for the normal control group, and 0.60 +/- 0.12 (p < 0.01) and 0.40 +/- 0.15 (p < 0.01) for the diabetic control groups with and without empty capsules. The authors conclude from these results that, given sufficient beta-cell mass, a BAP without any vascular access can respond appropriately to an increase in blood glucose concentration, without overshoot hypoglycemia and within a lag lapse compatible with normal physiologic insulin delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗