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Biomedical subjects

W Qi

Publications and source records attributed to W Qi.

At least 73 records · Page 4Linked to original sources
PubMed1998

Ischemia/reperfusion-induced arrhythmias in the isolated rat heart: prevention by melatonin.

Cardiac arrhythmias during ischemia/reperfusion are believed to be related to free radicals generated in the heart especially during the period of reperfusion. Since melatonin functions as a free radical scavenger and antioxidant, the ability of this molecule to influence cardiac arrhythmias was investigated. The pineal secretory product, melatonin, reduced the incidence and severity of arrhythmias induced by ischemia/reperfusion due to ligation of the anterior descending coronary artery in the isolated rat heart. Melatonin was either infused during both the ischemia and reperfusion periods or only late in the ischemia period and throughout reperfusion. The percentage of hearts that developed cardiac arrhythmias during reperfusion as indicated by the incidence of premature ventricular contraction (PVC) and ventricular fibrillation (VF) were recorded. Melatonin either infused during both the ischemia and reperfusion periods or during essentially the period of reperfusion greatly reduced PVC and VF due to occlusion and reopening the anterior descending coronary artery. Presumably melatonin's beneficial effect in reducing cardiac arrhythmias was due in part to its free radical scavenging activity, which is greatly assisted by the rapidity with which it is taken up into cells. Previous studies have shown that vitamin C is effective in reducing the severity of cardiac arrhythmias induced by ischemia/reperfusion; thus, we also compared the efficacy of melatonin with this well-known antioxidant. Melatonin was more potent than vitamin C in protecting against arrhythmias induced by ischemia/reperfusion. Besides melatonin's function as a broad spectrum free radical scavenger, melatonin may have also reduced cardiac arrhythmias due to its regulation of intracellular calcium levels, i.e., by preventing calcium overloading, or due to its ability to suppress sympathetic nerve function and reduce adrenergic receptor function in the myocardium. Additional studies into the mechanisms of melatonin's action in reducing cardiac arrhythmias due to ischemia/reperfusion or other causes are warranted because of the possible application of this information to humans with heart disease.

Animals↗
PubMed1998

Localization of pNT22 70 kDa heat shock cognate-like protein in the plasma membrane.

It has been argued that 70 kDa heat shock cognate (hsc73)-like molecules may be expressed on the surface of certain cells, but direct evidence of this has yet to be found. To clarify whether this molecule belongs to hsc73 itself, the membrane protein fraction of Daudi cells was isolated by Triton X-114 phase separation and the reactivity of this membrane protein fraction was assessed with monoclonal antibodies (mAbs) which react with 70 kDa heat shock protein (hsp) family, i.e., NT22, A15 and 3A3. In western blotting analysis, mAb NT22-defined protein (pNT22) was clearly detected as a membrane protein of Daudi cells with an approximate molecular size of 70 kDa, whereas pNT22 was not recognized by anti-cytoplasmic hsc73/hsp72 mAbs A15 or 3A3. By using deleted recombinant hsc73 proteins, it was determined that mAb NT22 recognizes the N-terminal 350-372 amino acid stretches of the hsc73 protein. mAb NT22 also reacted with the cell surface protein of Daudi cells in FACS analysis. Taken together, our present data strongly suggest that pNT22 may be a novel hsc73-like protein that is localized in the plasma membrane.

Antibodies, Monoclonal↗
PubMed1997

[Immunohistochemical study on the distribution and coexistence of SP, VIP and NPY in the rat submandibular gland].

The distribution and coexistence of SP, VIP and NPY in the submandibur gland of rat have been studied with immunohistochemical ABC methods. The results indicated that SP, VIP and NPY-IR nerve fibers were presented as varicose and linear profiles, which mainly travelled around acini, duct and blood vessels. The ganglion cells in submandibular gland showed SP, VIP and NPY-IR all positive immunocytochemically. The findings indicated that the neuropeptides were coexisted in the same neuron body and might play the role of regulation of the secretary activity and effective blood supply.

Animals↗
PubMed1997

[Clinical analysis of 39 cases of hepatitis E in pregnancy].

OBJECTIVE: To introduce clinical manifestations and treatment of hepatitis E in pregnancy. METHODS: Thirty-nine cases of hepatitis E in pregnancy, were analysed from June. 1992 to Jun. 1994, retrospectively on its epidemiologic characteristics, clinical manifestations and prognosis. RESULTS: The prognosis of sporadic cases of hepatitis E in pregnancy was good and its main complications were premature rupture of membranes, uterine inertia and fetal distress. CONCLUSIONS: Sporadic case is the main form of hepatitis E in pregnancy in Beijing. Active treatment and intensive monitoring would improve its prognosis.

Adult↗
PubMed1996

Effect of cytoplasmic domain mutations on the agonist-stimulated ligand binding activity of the platelet integrin alphaIIbbeta3.

Function of the platelet integrin alphaIIbbeta3 is regulated by agonist-generated signals interacting with its cytoplasmic tails. When alphaIIbbeta3 is expressed in Epstein-Barr virus-transformed B lymphocytes, stimulation of the cells with phorbol 12-myristate 13-acetate results in alphaIIbbeta3-mediated lymphocyte adherence to immobilized fibrinogen, as well as soluble fibrinogen binding to alphaIIbbeta3, indicating that agonists increase the affinity of alphaIIbbeta3 for fibrinogen in these cells. To address the contribution of the alphaIIb and beta3 cytoplasmic tails to this process, we mutated each tail and expressed the mutants in B lymphocytes. Truncation of the alphaIIb tail did not impair unstimulated or stimulated lymphocyte adherence to fibrinogen, regardless whether the truncation was proximal or distal to the conserved GFFKR sequence. However, deleting GFFKR or replacing it with alanines markedly reduced alphaIIbbeta3 expression due to impaired intracellular assembly of alphaIIbbeta3 heterodimers, probably due to a mutation-induced change in the conformation of alphaIIb. Introducing beta3 mutations known to impair alphaIIbbeta3 function in platelets into the cytoplasmic tail of beta3 in lymphocytes also impaired alphaIIbbeta3 function in these cells. These studies demonstrate that the cytoplasmic tail of alphaIIb is not required for alphaIIbbeta3 function in lymphocytes, although the presence of GFFKR in the alphaIIb tail is required for alphaIIb to interact with beta3. Additionally, they indicate that signals interacting with the beta3 cytoplasmic tail are responsible for the ability of agonists to stimulate alphaIIbbeta3 function.

Amino Acid Sequence↗
PubMed1996

Inhibition of natural killer cell cytotoxicity by cell growth-related molecules.

Certain MHC class I molecules on target cells are known to inhibit the cytotoxic action of NK cells. By using monoclonal antibody (mAb) Cho-1, we have found inhibitory non-MHC class I cell surface molecules that are noncovalently-associated with 200 kDa and 40 kDa antigens. Poly I-C-induced rat NK cells were not cytotoxic to rat fetus-derived fibroblast WFB cell line. In contrast, NK cells were cytotoxic to H-ras oncogene-induced transformants of WFB, W14 and W31. FACS analysis indicated that mAb Cho-1 reacts with WFB, but not with W14 and W31 cells. Thus, this antigen may disappear concomitantly with cell growth and transformation. Cho-1 antigens were also expressed on other NK-resistant lines, such as mouse BALB3T3 fibroblast, EL-4 lymphoma and human fibroblast HEPM. However, they were not expressed on NK-sensitive mouse YAC-1 and H-ras transformant (Brash) of BALB3T3 cells. Furthermore, treatment of target cells with IFN-gamma clearly induced the cell surface expression of Cho-1 antigens, and conferred a resistance to NK cytolysis on target cells. These data strongly suggest that Cho-1 antigen expression may correlate with target cell susceptibility to NK cells. Indeed, treatment of NK-resistant WFB as well as HEPM cells with F(ab')2 fragments of mAb Cho-1 resulted in the acquisition of susceptibility to NK cytolysis. Cho-1 antigens may be novel molecules that regulate the NK resistance of cells.

Animals↗
PubMed1996

Finite element analysis and experimental studies on the thickness resonance of piezocomposite transducers.

Finite element method (FEA) has been used to calculate the thickness resonance frequency and electromechanical coupling coefficient kt for 2-2 piezocomposite transducers. The results are compared with that of the effective medium theory and also verified by experiments. It is shown that the predicted resonance frequencies from the effective medium theory and the unit cell modeling using FEA deviate from the experimental observations for composite systems with a ceramic aspect ratio (width/length) more than 0.4. For such systems, full size FEA modeling is required which can provide accurate predictions of the resonance frequency and thickness coupling constant kt.

Equipment Design↗
PubMed1996

[Dynamic change of beta 2-microglobulin in hemodialysis].

In order to study the dynamic clearance of total beta 2-microglobulin in the body, two-compartment theory and perturbation solution were applied in our study. Based on the rate of formation of beta 2-microglobulin in the body and the mode of transmission and mass transfer resistance of solute, the concept of week clearance index of beta 2-microglobulin (R value) was suggested. Its theoretical value is more than 40%. Thirty-two patients undergoing dialysis with high-efficiency dialyzer were studied and data were processed in a computer. The results showed that when R value was more than 40%, the clinical manifestation of amyloidosis carpal tunnel syndrome induced by increase of beta 2-microglobulin was alleviated obviously. It makes up for the limitation of KT/V or TA Curea that were used only to estimate adequate dialysis of small molecules. It is shown that the concept of week cleacance index of beta 2-microglobulin improves the estimation of adequate dialysis.

Adult↗
PubMed1995

Agonist-stimulated ligand binding by the platelet integrin alpha IIb beta 3 in a lymphocyte expression system.

The ligand binding activity of the platelet integrin alpha IIb beta 3 is initiated by agonist-generated intraplatelet signals. We studied this process in vitro by expressing recombinant alpha IIb beta 3 in Epstein-Barr virus-immortalized B lymphocytes. We found that phorbol ester stimulation induced the adhesion of lymphocytes expressing alpha IIb beta 3 to immobilized fibrinogen. Moreover, replacement of the transmembrane and cytoplasmic domains of the alpha and beta subunits of alpha IIb beta 3 with those of alpha L beta 2 significantly increased adherence, whereas replacement of only the cytoplasmic domains significantly decreased adherence. This suggests that transmembrane segments are involved in the agonist-induced modulation of alpha IIb beta 3 activity. Similar results were seen when the alpha IIb beta 3 activation-dependent monoclonal antibody PAC-1 was substituted for immobilized fibrinogen. We also found that the adherence of lymphocytes expressing beta 3 with either of the two alpha IIb/alpha L chimeras was similar to that of cells expressing alpha IIb beta 3, whereas the adherence of cells expressing alpha IIb with either of the two beta 3/beta 2 chimeras was substantially decreased, suggesting that the identity of the cytoplasmic domain of beta 3, but not of alpha IIb, is critical for alpha IIb beta 3 function. This report indicates that B lymphocytes contain signal transduction pathways involving protein kinase C that can increase the ligand binding activity of alpha IIb beta 3 and demonstrates the utility of these cells as an expression system for the study of agonist-stimulated alpha IIb beta 3 function.

Amino Acid Sequence↗
PubMed1995

Effectiveness of chest tube clamping in massive hemothorax.

OBJECTIVE: To test the effectiveness of chest tube clamping in massive hemothorax. DESIGN, MATERIALS AND METHODS: This was assessed in 32 spontaneously breathing Yorkshire piglets with 2.5 mm (groups A and B) or 4.0 mm (groups C and D) lacerations of the thoracic aorta. MEASUREMENTS: Hemodynamics, blood loss, length of survival, and arterial blood gases (on 100% oxygen) were monitored. The four groups of eight animals all had chest tubes but groups A and C had these tubes clamped. Measurements were made at baseline, immediately after aortic injury, and every 15 minutes until death. RESULTS: Groups C and D survived 39 +/- 4 and 38 +/- 5 minutes respectively compared to 68 +/- 6 and 70 +/- 4 minutes in groups A and B. Total blood loss was not statistically significantly different among the four groups (1225 +/- 72, 1312 +/- 84, 1020 +/- 90, and 1110 +/- 84 mL for groups A, B, C, and D respectively). The rate of blood loss was greater in groups C and D (29.4 +/- 0.2 mL and 30.1 +/- 0.3 mL/min) compared with 14.7 +/- 0.5 mL and 16.0 +/- 0.9 mL/min respectively in groups A and B. Blood loss rate was similar with clamped or unclamped chest tubes. All groups had similar baseline cardiac output (3.5 to 3.8 L/min) and arterial blood pressures (110 to 114 mm Hg) with a greater decrease in these parameters following the larger lacerations and no difference with chest tube clamping. Arterial PO2 decreased from approximately 400 to 50 mm Hg with clamping but only decreased to approximately 350 mm Hg without clamping. The hypoxia was associated with significant hypercapnea (PCO2 of 78 mm Hg). CONCLUSIONS: Chest tube clamping did not decrease hemorrhage or mortality but worsened gas exchange without improving hypotension and is therefore not recommended in the treatment of massive hemothorax.

Animals↗
PubMed1995

Fluid and electrolyte deficit with prolonged pneumatic antishock garment application.

OBJECTIVE: When trauma victims are within 1 hour of definitive surgical care, prehospital pneumatic antishock garment (PASG) application has not improved outcome. A resuscitative role for PASG has been suggested when transport time is longer (e.g., 4 hours). We assessed the fluid and electrolyte cost of treating posthemorrhagic hypotension with the PASG in 16 anesthetized Yorkshire piglets (30 to 32 kg). DESIGN: Hypotension [30 mm Hg drop in carotid arterial blood pressure (CBP)] was produced by arterial line bleeding. Hemodynamics, serum electrolytes, lactate, and tissue edema (limb circumference) were monitored. MATERIALS AND METHODS: In eight animals (group 1), PASG was inflated to maintain prebleed CBP for 4 hours. In group 2, the hypotension was untreated for 4 hours. After 4 hours, shed blood (over a period of 15 minutes) and normal saline (1.5 mL/kg/minute) were infused until CBP returned to normal baseline values. MEASUREMENTS AND MAIN RESULTS: Shed blood alone did not restore baseline CBP. Serum K+ increased from a baseline of 3.9 to 9.1 mmol/L in group 1, with no significant change in group 2. Serum lactate rose from 1.8 to 24.1 and from 1.7 to 6.8 mmol/L in groups 1 and 2, respectively. After 4 1/2 hours, an increase in thigh circumference (6.4 +/- 1.4 vs. 1.9 +/- 1.0 mm) and intravenous fluid required after returning shed blood (626 +/- 36 vs. 324 +/- 22 mL) was greater in group 1 (means +/- SD, p < 0.05). Other serum electrolyte values were similar for the two groups. CONCLUSIONS: We conclude that fluid deficit, lactic acidosis, tissue edema, and hyperkalemia are all greater with prolonged PASG application when compared with the untreated hypotensive state. These findings must be considered when suggesting more prolonged PASG application.

Animals↗
PubMed1995

Pulmonary function and posture in traumatic quadriplegia.

OBJECTIVE: To determine optimum posture for pulmonary function in traumatic quadriplegia. DESIGN: Lung function with changes in posture of normal healthy volunteers was compared with that of traumatic quadriplegic patients. MATERIALS AND METHODS: Functional residual capacity (FRC), Forced vital capacity (FVC), and arterial blood gases in room air were compared in 16 male patients aged 18 to 32 years, 8 of whom (group I) sustained traumatic quadriplegia (C6 to C7) at least 1 year previously, and 8 of whom (group II) were healthy volunteers. MEASUREMENTS: FRC, FVC and blood gases were measured after 15 minutes in the following random positions: 20 degrees head down, horizontal, 35 degrees head up, 60 degrees head up, and 90 degrees head up. MAIN RESULTS: FRC was lower in all positions in group I but there was a similar directional change in FRC with posture in both groups. The greatest increase in FRC occurred in group I between the 35-degree head up and the 60-degree head up positions. Group I, in contrast to group II, decreased FVC from the 35-degree head up to the 60-degree head up position. There were no significant changes in PO2 with position in group II, but quadriplegic patients showed PO2 improvement from the head down to the horizontal and 60-degree head up positions. CONCLUSIONS: In traumatic quadriplegia, maximum oxygenation and patency of alveoli (FRC) are achieved in the 60- to 90-degree head up positions. In contrast to normal subjects, no changes in FRC and FVC occurred between the horizontal and 35-degree head up positions in quadriplegia. The optimum position in these patients for physiotherapy (deep breathing and coughing, as reflected by maximum FVC) is the horizontal or 35-degree head up position. These differences in lung volumes and oxygenation with posture may be important in optimizing respiratory care in traumatic quadriplegia.

Adult↗
PubMed1995

[Dynamic changes of the platelet granule membrane glycoprotein level in patients with acute myocardial infarction before and after thrombolysis].

Platelet granule membrane glycoprotein (GMP-140) level was measured by using 125I labelled monoclonal antibody in 37 patients with acute myocardial infarction before and after thrombolytic therapy. In a nonthrombolysis group, it was shown that platelet GMP-140 increased significantly at the moment of admission and reached peak value 48 hours after AMI attack, then it decreased gradually and returned to baseline on the fifth day. In the thrombolysis group, with the patency of infarct related arteries, it dropped quickly (1-6 hours) after thrombolytic therapy; if the infarct related arteries were not patent, platelet GMP-140 increased rapidly after thrombolytic therapy and reached the highest at 6 hours, then it returned to baseline on the third day. It is suggested that the changes of platelet function could play an important role in thrombus formation and lysis; the rapid decrease of the number of GMP-140 molecules on platelet surface might be a new index for the pateacy of infarct related arteries.

Adult↗
PubMed1994

Transformation-associated 86 kDa natural killer target molecule expressed on the mouse, rat and human cell surface.

We previously reported on the 86 kDa natural killer target molecule associated with transformation of the oncogene-transfected rat fibroblasts. This molecule may participate in the lethal hit phase of cytotoxicity by natural killer (NK) cells. Originally, this molecule was defined by mAb109, but mAb109 could react only with rat tumor lines. In this report, to determine whether the 86 kDa molecule could be utilized as a natural killer target molecule in mammalian cells, we developed a polyclonal anti-86 kDa antibody (pAb109). Our data indicated that pAb109 preferentially reacted with NK-susceptible lines such as mouse YAC-1, rat W31 and human K562 cells, but reacted only weakly with NK-resistant mouse EL-4, rat fetal fibroblast WFB and human fetal fibroblast HEPM. In a cytotoxicity experiment, pAb109 F(ab')2 fragments could inhibit the cytolysis by NK cells of W31 and K562 cells. However, these fragments did not inhibit the cytotoxicity of non-NK cells such as CD3+, CD4-, CD8- T cell receptor alpha beta- T cells (presumably gamma delta T cells) to W31 cells. Taken together, these data suggest that the cell transformation-associated 86 kDa molecule may be critical in NK cytotoxicity, and a candidate for the NK target structure in mammalian tumor cells.

3T3 Cells↗
PubMed1993

Cellular stress- and transformation-associated cell surface antigens expressed on human and rodent tumor cells.

Stress-induced proteins may have significant roles in anti-tumor resistance. To clarify the immunobiological roles of these proteins, we first developed monoclonal antibody (mAb) H1A that detects the HeLa cell-surface antigens whose expression was enhanced by treatment of the cells with physico-chemical stressors, such as heat, H2O2 and tumor necrosis factor. H1A (IgM) detects several molecules with mol. wt. 30, 43, 75, 90, 100, 120 and 150 kDa in Western blot analysis of HeLa cell lysates. Although the antigen was constitutively expressed on the HeLa cell surface, the cell-surface expression of H1A-defined antigen was rapidly enhanced (within 1 h) after heat treatment of HeLa cells. H1A antigens were also transformation-associated, since 1) the activated oncogene-transformed fibroblasts expressed the antigens, but parental nontransformed cells did not, and 2) certain human neoplastic but not normal cells strongly expressed the antigens. Furthermore, H1A mAb also partly blocked the cytotoxicity of purified protein derivatives-stimulated human T cell receptor gamma delta-type T cells towards HeLa cells. Taken together, these data indicate that H1A-defined stress-inducible proteins may play a vital role in anti-tumor resistance by cytotoxic T cells.

Adenosine Triphosphate↗