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Biomedical subjects

Q Yang

Publications and source records attributed to Q Yang.

At least 379 records · Page 21Linked to original sources
PubMed1996

Combined use of 111In-DTPA-D-Phe-1-octreotide (OCT) and 123I-vasoactive intestinal peptide (VIP) in the localization diagnosis of medullary thyroid carcinoma (MTC).

Although serum calcitonin and CEA are sensitive indicators for the presence of medullary thyroid carcinoma (MTC), the localization of tumor sites may be very difficult. In an approach to localize MTC lesions we performed comparative in vivo studies in 12 patients with primary MTC and in 4 patients with suspected recurrent MTC using 123I-VIP (150 MBq/1 microgram) and 111In-DTPA-D-Phe-1-octreotide (111In-OCT; 150 MBq/1 microgram). Despite elevated calcitonin values in all patients with suspected recurrent or metastatic lesions, both ultrasound and computed tomography (CT) were unable to localize a tumor site. 111In-OCT localized the primary tumor in the thyroid gland in 7 of 11 patients (63.5%). In 2 of 4 patients (50%) with suspected recurrent MTC, pathological uptake of 111In-OCT in the mediastinum or liver was demonstrable. In none of the 11 patients did 123I-VIP-receptor scanning indicate primary, recurrent, or metastatic tumor lesions. In vitro binding studies showed an absence of high-affinity VIP receptors in MTC tissue, whereas high-affinity 111In-OCT receptors were present in 4 of 6, and low-affinity 123I-VIP as well as 111In-OCT receptors were present in 6 of 6 MTC tissue samples. We conclude that somatostatin receptor scanning using 111In-OCT may visualize primary MTC, but it has only a low sensitivity in the detection of recurrent disease. The 123I-VIP-receptor scan is not helpful in the localization diagnosis of primary or recurrent MTC.

Adult↗
PubMed1996

123I-vasoactive intestinal peptide (VIP) receptor scanning: update of imaging results in patients with adenocarcinomas and endocrine tumors of the gastrointestinal tract.

Recent data suggest that functional receptors (R) for vasoactive intestinal peptide (VIP) are expressed on various tumor cells. The high-level expression of VIPR on tumor cells provided the basis for the successful use of 123I-labeled VIP for the in vivo localization of intestinal adenocarcinomas and endocrine tumors. We here report an update of our imaging results using 123I-VIP (150-200 MBg/1 microgram/patient) in 169 patients. In patients with pancreatic adenocarcinomas without liver metastases, the primary/recurrent tumor was visualized in 16 of 18 patients (89%) and liver metastases were imaged in 15 of 16 patients. In 11 of 12 patients with colorectal adenocarcinomas, the primary/recurrent tumor (92%) was imaged by 123I-VIP. Also, in 21 of 25 patients, liver metastases (84%); in 3 of 6 patients, lung metastases (50%); and in 4 of 5 patients, lymph-node metastases (80%) were imaged by 123I-VIP. In 10 of 10 patients with gastric adenocarcinomas, the primary/recurrent tumor; in 3 of 4 patients, liver metastases; and in 2 of 2 patients, lymph-node metastases were visualized by 123I-VIP. 123I-VIP localized primary intestinal carcinoid tumors in 15 of 17 patients (88%) and 8 of 10 primary insulinomas (80%). We conclude that the 123I-VIPR scintigraphy localizes intestinal adenocarcinomas and endocrine tumors as well as metastatic tumor sites.

Adenocarcinoma↗
PubMed1996

Phage display of proteases and macromolecular inhibitors.

We describe methods for displaying the protease trypsin and the macromolecular protease inhibitor ecotin on the surface of filamentous phage. Our strategy for selecting variant ecotins against target proteases is also described. We believe that the two proteins that have been displayed serve as ideal models for studying molecular recognition in detail. The ability to search efficiently through a large number of variant proteins for desired properties using phage display technology and the in vitro selection methods described opens a new avenue for studying protein-ligand interactions, as well as creating proteins with novel functions.

Bacterial Proteins↗
PubMed1996

Translocation of phospholipase C-gamma 2 induced by in vitro activation of protein tyrosine kinase activity in mast cell lysates.

Aggregation of the high-affinity receptor for IgE (Fc eta RI) on the surface of intact or permeabilized rodent mast cells results in tyrosine phosphorylation of phospholipase C-gamma 1 (PLC gamma 1) and PLC gamma 2, and translocation of both isozymes to the particulate fraction. We report here that activation of resident tyrosine kinases by the addition of adenosine triphosphate (ATP), orthovanadate, and Mg2+ to rat basophilic leukemia cell (RBL) lysates induces an association of PLC gamma 2 with the Triton-insoluble particulate fraction, with a parallel increase in tyrosine phosphorylation of cellular proteins. Both PLC gamma 2 translocation and tyrosine phosphorylation are supported by millimolar Mg2+ or Mn2+ but not by Ca2+. Both tyrosine phosphorylation and PLC gamma 2 translocation are inhibited by genistein. These data suggest that in vitro activation of tyrosine kinase activity in broken cell preparations induces the formation of association between PLC gamma 2 and ligands with the Triton-insoluble fraction.

Adenosine Triphosphate↗
PubMed1996

Eliprodil prevents expression of the 70 kDa heat shock protein in MK801-injured neurones.

The present study examined whether eliprodil (SL 82.0715), an N-methyl-D-aspartate (NMDA) receptor antagonist acting on the polyamine sites induced expression of the 70 kDa heat shock protein (HSP70) in the rat brain. Whereas the NMDA channel blocker MK801 consistently induced HSP70 in posterior cingulate and retrosplenial cortices, eliprodil had no such effects even at the highest dose (50 mg/kg, intraperitoneally), supporting the idea that injury to the cerebrocortical neurones by NMDA receptor antagonists is probably related to specific sites of the receptor. Furthermore, eliprodil, given immediately after injection of MK801, blocked the effects of MK801 on HSP70. The result is discussed in terms of high affinity of eliprodil for the sigma receptor.

Animals↗
PubMed1996

[Dynamic changes of amino acids in extracellular fluid in rat hippocampus in cases of cerebral ischemia].

OBJECTIVE: To study the changes of excitatory amino acid (EAA) in patients with cerebral ischemia. METHODS: We observed dynamic changes of EAA in extracellular fluid by intracerebral microdialysis inserted in hippocampus through stereotaxic method with modified Pulsinelli's model of four vessels occlusion. RESULTS: The concentration of Glu was 5.88 +/- 1.40 and 11.2 +/- 1.5 micromol/L in patients with incomplete cerebral ischemia after 30 minutes and 60 minutes, and the concentration of Asp was 2.72 +/- 0.24 and 4.4 +/- 0.6 micromol/L. The concentration of Glu was 15.1 +/- 1.6 micromol/L and 17.9 +/- 1.6 micromol/L in patients with complete cerebral ischemia after 30 minutes and 60 minutes, and the concentration of Asp was 8.2 +/- 1.0 and 12.1 +/- 1.1 micromol/L. The concentration of Glu and Asp was 1.75 +/- 0.88 micromol/L and 0.24 +/- 0.09 micromol/L in the controls. CONCLUSIONS: In this study, the concentration of Glu and Asp in patients with cerebral ischemia was significantly increased than in the controls, and the more serious ischemia was, the more release of EAA. It is suggested that Dansen injection can reduce the release of EAA by cerebral cells in case of ischemia.

Amino Acids↗
PubMed1996

[Enhancement of antitumor effect of cisplatin on human ovarian cancer by cyclosporin A in vitro and in vivo].

OBJECTIVES: To investigate the enhanced impact of cyclosporin A (CsA) on antitumor activity of cisplatin (DDP) for human ovarian cancer cells. METHODS IN VITRO STUDIES: human ovarian adenocarcinoma cells (COC1) and its resistant subline (COC1/DDP) were cultured separately with 4 different preparations: (1) normal saline; (2) CsA alone; (3) DDP alone; (4) DDP plus CsA. After 72 hours, the numbers of tumor cells were counted under microscope. Furthermore, 3H-thymidine incorporation tests were performed on the above 4 systems, and the inhibitory rate of tumor growth were calculated. In vivo studies: normal saline or 2mg/kg of DDP and 5mg/kg of CsA was injected intraperitoneally to nude mice with COC1/DDP xenograft cancer every 3 day for 3 times. The changes of tumor volumes and its pathological appearances were compared before and after treatment. RESULTS: IN VITRO STUDIES, DDP combined with CsA exhibited a synergistic cytotoxic effect on COC1 and COC1/DDP cells. The decrease of tumor cell numbers reached 24%-36%, 48%-60% of controls respectively. The inhibitory rates of DNA synthesis of these tumor cells, measured by 3H-TdR incorporation tests, were greater in DDP plus CsA group than those in DDP alone group (64.7% 63.9% versus 39.6% 25.1%, P < 0.01). The greater inhibitory rates of CsA+DDP regimen (81.4%) was also shown in vivo studies when compared with DDP alone regimen (49.1%) (P < 0.01). There were significant decreases of tumor cell density and nuclear mitosis in the combined group as compared with that of the DDP alone group (P < 0.01). CONCLUSIONS: The combination of DDP with 2 micrograms/ml of CsA yields enhancement of antitumor effect on human ovarian cancer. This study suggests that CsA may be used clinically as an antitumor enhancement of DDP for the treatment of ovarian adenocarcinoma.

Adenocarcinoma↗
PubMed1996

Theory of wear as related to the Björk-Shiley Delrin disc heart valve.

BACKGROUND AND AIMS OF THE STUDY: Mechanical wear is an important consideration for the Björk-Shiley Delrin (BSD) heart valve, the disc of which is periodically impacted against the inlet strut by the momentum of the blood flow during closure. Impact wear theory was used in designing experiments as well as establishing theoretical evaluation and projections of wear life. MATERIALS AND METHODS: The experimental apparatus involved a pivotal hammer device where the striking face could be varied by the inclusion of distinct spherical shapes; the sharper the radius, the higher the contact stress induced. The striking speed could be varied between one and three m/s, and the repetition rate between 2-50 Hz. Blood was simulated with an aqueous 42% glycerol solution. The same wear mechanism was induced on Delrin occluder disc specimens as the one governing the wear observed in Delrin occluder discs of some of the explanted BSD heart valves; thus two wear parameters, c and g, were established for the prediction of wear in BSD implants. The experimental runs were repeated on as many as four simultaneous specimens, for up to 7.5 x 10(7) cycles. RESULTS: The wear history was found to comprise three distinct regions, corresponding to (a) initial plastic deformations; (b) zero wear; and (c) measurable wear. The zero wear region produced very little change in the contact dimensions, and represented a fatigue threshold to the progress of a wear scar. Procedures for analytical establishment of the zero wear limit are outlined in the paper. Measurable wear was governed by the process of increasing conformance between the repetitively contacting surfaces. The differential equation of wear was then used with the physical parameters c and g previously determined experimentally. CONCLUSION: The maximum depth of the wear scar after cycling the equivalent of 20 years was predicted to be 278 microns. This value appears to represent a safe dimension for BSD heart valves.

Biocompatible Materials↗
PubMed1996

[Studies on inhibition of activated oncogene expression by antisense RNA].

In this paper, the sense and antisense mammalian expression vectors of T24-ras activated oncogene were introduced into cultured NIH3T3 cells in sense-->antisense and antisense-->sense orders. The transfected cells were selected by drug selection. The morphology change, Southern hybridization, frequency of soft agar colonies and the detection of P21 amount were investigated. The results showed that the sense recombinant could cause the malignant transformation of NIH3T3 cells while the antisense recombinant could inhibit this kind of transformation. Furthermore, the inhibitory effect varied according to the different transfected orders.

3T3 Cells↗
PubMed1996

Analysis of the alpha2C-adrenergic receptor gene promoter and its cell-type-specific activity.

As an initial approach to define the regulatory elements and transcriptional factors that account for cell-restricted expression of the alpha2c-adrenergic receptor (AR) gene, we isolated and characterized the receptor gene and identified regions of the gene conferring cell-specific expression. A 4300-nucleotide (nt) fragment of the 5'-flanking region of the rat alpha2c-AR gene was isolated from a genomic library. The genomic sequence contained the uninterrupted sequence of the 5'-untranslated region of a previously isolated alpha2c-AR cDNA clone indicating the lack of introns in the 5' gene segment. RNase protection assays and/or RNA blot analysis indicated the expression of alpha2c-AR mRNA in rat brain but not in kidney or liver, which is consistent with the major expression of this gene in neuronal tissue. The 5' gene segment was used to identify sites of transcriptional initiation and promoter activity by RNase protection assays and transient transfection of reporter gene constructs. With the use of RNA probes progressively upstream of the translational start site, RNase protection assays with rat brain total RNA indicated multiple sites of transcriptional initiation within a approximately 70-nt span (-660 to -730 nt 5' to the translational start codon). The zone of transcriptional initiation was part of a larger GC-rich area of the 5' gene segment that is a characteristic of genes initiating transcripts at multiple sites. The promoter activity of this zone of transcriptional initiation and the influence of gene segments 5' to this area were addressed using chloramphenicol acetyl transferase reporter gene constructs. Transient transfection of reporter gene constructs indicated that a 96-nt gene fragment (-699/-603 relative to the translational start codon) was sufficient to direct transcription in the neuroblastoma X glioma hybrid cell line NG108-15, a cell line expressing the endogenous alpha2c-AR. Promoter activity was not observed in constructs lacking the zone of transcriptional initiation. The promoter segment was inactive when introduced into the rat glioma cell line C6B4, the rat submandibular cell line RSMT-A5, and the rat pancreatic beta cell line RIN-5AH, all of which do not express the endogenous alpha2c-AR gene. Upon incubation with nuclear extracts, a 129-nt fragment encompassing the promoter exhibited a gel mobility shift pattern that was specific for cells expressing the receptor protein and involved a nuclear protein that recognized a Sp1 oligonucleotide. These data indicate that a 96-nt gene promoter segment of the alpha2c-AR gene functions in a cell-type-specific manner.

Animals↗
PubMed1996

[Antitussive, expectorant and anti-inflammatory effects of rhizoma Cynanchi stauntonii].

Experiments indicated that the ethanol extract and ether extract from Rhizoma Cynanchi Stauntonii showed obvious antitussive and expectorant effects in mice with stomach administration. The antitussive effect of ethanol extract was stronger than the expectorant effect. The water extract showed a certain expectorant effect but no marked antitussive effect with oral administration. Obvious anti-inflammatory effect was observed on croton oil-caused mouse ear swell with intraperitoneal injection.

Animals↗
PubMed1996

[Regional brain calcium change in rabbit cerebral ischemia].

OBJECTIVE: To study whether regional brain calcium change would be an important factor for ischemic neuranal damage and whether calcium antagonist would exert protective effects on cerebral ischemia. METHODS: OCPC autoanalyzer method, was used to measure the regional brain calcium and observe the influence of flunarizine (FNZ) 48 hours after the rabbit middle cerebral artery occlusion (MCAO). RESULTS: 48 hours after MCAO, the calcium in the ischemic middle cerebral artery territory was 10.8 times as much as that in the pseudo-occluded controls, and FNZ could significantly decrease the ischemic brain calcium (P < 0.05) and the ischemic cerebral edema (P < 0.01). CONCLUSION: Caoverload was animportant factor leading to ischemic neuronal death, and FNZ has protective effects on cerebral ischemia.

Animals↗
PubMed1996

[Establishment of human ovarian cancer cisplatin resistant cell line COC1/DDP and its mechanism of resistance].

OBJECTIVE: To establish cisplatin (DDP)-resistant subline of human ovarian cancer and investigate the mechanism responsible for resistance to DDP. METHODS: A DDP-resistant human ovarian adenocarcinoma cell subline (COC1/DDP) was developed by contineous stepwise selection in increasing concentration of DDP from the parent cell line COC1 in vitro. The multiple changes of biological properties in COC1/DDP cell line were determined. RESULTS: COC1/DDP cells were of 6.5-fold resistance to DDP and displayed significant cross-resistant with carplatin and mitomycin C, but still remained sensitive to 5-fluorouracil and adriamycin. As compared to the parent cells, in COC1/DDP cells: the doubling time was reduced by 12.9%. Cellular content of DDP was diminished by more one half and the DNA-interstrand cross-links (ISC) was lower than that of the sensitive cells. Evidence of P-glycoprotein overexpression was not shown in COC1 and COC1/DDP cell lines by means of immunohistochemical method. CONCLUSIONS: The primary factor causing COC1/DDP resistance to DDP is the reduction of intracellular platinum accumulation and DNA ISC formation. The resistance is not considered to be associated with the multidrug resistant and P-glycoprotein.

Adenocarcinoma↗
PubMed1996

[Gas chromatographic analysis of molinate residue in rice].

We have developed a method for determining molinate residue in rice by gas chromatography. In our study, the rice sample was extracted with acetonewater (1 + 1). After filtering, the filtrate was acidified to pH 3.0-3.5 and re-extracted with petroleum. The extract was cleaned up on a florisil column and followed by analysis with GC/FPD. The linear range of the method was 0-5 micrograms/ml. the detection limit was 0.013 mg/kg for a rice sample of 20 g. The average recoveries of spiked samples ranged from 87.0%-96.7%. The relative deviation standard was less than 5.7%. The experimental verification of this method by extramural departments and its application to determination of rice samples demonstrate that this method is sensitive, reliable and suitable for analysis of molinate residue in rice.

Azepines↗
PubMed1996

[Changes of superoxide dismutase and lipid peroxide in lung tissue of rats after intratracheal injection of crocidolite and benzo(a) pyrene].

Wistar rats were divided into 4 groups: control group, Cro group, B(a) p group and Cro plus B(a) p group. Samples of lung tissue were collected 90, 180, 270, 360 and 540 days after the third time of intratracheal. The superoxide dismutase (SOD) activity, the level of lipid peroxide (LPO) and the ratio of SOD/LPO were observed. The results indicated that there was a synergistic action of Cro. and B(a) p.

Animals↗