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Biomedical subjects

Q Yao

Publications and source records attributed to Q Yao.

At least 55 records · Page 3Linked to original sources
PubMed1999

Microglia exhibit clonal variability in eliciting cytotoxic T lymphocyte responses independent of class I expression.

Microglia are important immunoregulatory cells within the central nervous system (CNS). Viral infection of primary microglia and splenic macrophage clones revealed that both exhibited a heterogeneous, but relatively low, sensitivity to cytolysis mediated by CD8(+) cytotoxic T lymphocytes (CTL). The majority of clones were poor in processing and presenting epitopes, despite triggering lysis when coated with peptide. These characteristics were retained by stable microglia lines. Reduced lysis did not correlate with class I expression and IFN-gamma treatment only partially enhanced recognition. In contrast, targeting the epitope into the endoplasmic reticulum restored cytolysis to levels achieved with exogenous peptide. An inherent resistance to cytolysis was revealed by efficient engagement of T cells in competition assays and the inability of saturating peptide to enhance cytolysis. These data suggest that microglia heterogeneity in antigen processing, in addition to low sensitivity to CTL lysis, contributes to limited CD8(+) T cell responses and viral CNS persistence.

Animals↗
PubMed1999

Age-related variation in the interstitial tissues of the cardiac conduction system; and autopsy study of 230 Han Chinese.

The amount of fatty and fibrous tissues in 230 Han Chinese who died of noncardio-vascular diseases has been studied by a semi-quantitative method and analysed by chi-square test. The results have shown some consistency. Generally, in the sino-atrial node (SAN), fibrosis and fatty influtratin appear only after 40 years of age and increase one grade with every 20 years. The atrio-ventricular node (AVN) showed fatty change after 30 years of age and fibrosis appeared after 60. In the His bundle (HB), fatty infiltration and fibrosis appear after 40 years. The left bundle branch (LBB) showed similar changes. The appearance of fibrosis in the AVN seems to be later than that reported by Lev.

Adolescent↗
PubMed1999

Selection of CD8+ T cells with highly focused specificity during viral persistence in the central nervous system.

The relationships between T cell populations during primary viral infection and persistence are poorly understood. Mice infected with the neurotropic JHMV strain of mouse hepatitis virus mount potent regional CTL responses that effectively reduce infectious virus; nevertheless, viral RNA persists in the central nervous system (CNS). To evaluate whether persistence influences Ag-specific CD8+ T cells, functional TCR diversity was studied in spleen and CNS-derived CTL populations based on differential recognition of variant peptides for the dominant nucleocapsid epitope. Increased specificity of peripheral CTL from persistently infected mice for the index epitope compared with immunized mice suggested T cell selection during persistence. This was confirmed with CD8+ T cell clones derived from the CNS of either acutely (CTLac) or persistently (CTLper) infected mice. Whereas CTLac clones recognized a broad diversity of amino acid substitutions, CTLper clones exhibited exquisite specificity for the wild-type sequence. Highly focused specificity was CD8 independent but correlated with longer complementarity-determining regions 3 characteristic of CTLper clonotypes despite limited TCR alpha/beta-chain heterogeneity. Direct ex vivo analysis of CNS-derived mononuclear cells by IFN-gamma enzyme-linked immunospot assay confirmed the selection of T cells with narrow Ag specificity during persistence at the population level. These data suggest that broadly reactive CTL during primary infection are capable of controlling potentially emerging mutations. By contrast, the predominance of CD8+ T cells with dramatically focused specificity during persistence at the site of infection and in the periphery supports selective pressure driven by persisting Ag.

Amino Acid Sequence↗
PubMed1999

Beta-blocker use and survival in patients with ventricular fibrillation or symptomatic ventricular tachycardia: the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial.

OBJECTIVES: To evaluate whether use of beta-adrenergic blocking agents, alone or in combination with specific antiarrhythmic therapy, is associated with improved survival in persons with ventricular fibrillation (VF) or symptomatic ventricular tachycardia (VT). BACKGROUND: The ability of beta-blockers to alter the mortality of patients with VF or VT receiving contemporary medical management is not well defined. METHODS: Survival of 1,016 randomized and 2,101 eligible, nonrandomized patients with VF or symptomatic VT followed in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial through December 31, 1996 was assessed using Cox proportional hazards analysis. RESULTS: The 817 (28%) patients discharged from hospital receiving beta-blockers had less ventricular dysfunction, fewer symptoms of heart failure and a different pattern of medication use compared with patients not receiving beta-blockers. Before adjustment for important prognostic variables, beta-blockade was not significantly associated with survival in randomized or in eligible, nonrandomized patients treated with specific antiarrhythmic therapy. After adjustment, beta-blockade remained unrelated to survival in randomized or in eligible, nonrandomized patients treated with amiodarone alone (n = 1142; adjusted relative risk [RR] = 0.96; 95% confidence interval [CI] 0.64-1.45; p = 0.85) or a defibrillator alone (n = 1347; adjusted RR = 0.88; 95% CI 0.55 to 1.40; p = 0.58). In contrast, beta-blockade was independently associated with improved survival in eligible, nonrandomized patients who were not treated with specific antiarrhythmic therapy (n = 412; adjusted RR = 0.47; 95% CI 0.25 to 0.88; p = 0.018). CONCLUSIONS: Beta-blocker use was independently associated with improved survival in patients with VF or symptomatic VT who were not treated with specific antiarrhythmic therapy, but a protective effect was not prominent in patients already receiving amiodarone or a defibrillator.

Adrenergic beta-Antagonists↗
PubMed1999

In-hospital versus out-of-hospital presentation of life-threatening ventricular arrhythmias predicts survival: results from the AVID Registry. Antiarrhythmics Versus Implantable Defibrillators.

OBJECTIVES: This study describes the outcomes of patients from the Antiarrhythmics Versus Implantable Defibrillators (AVID) Study Registry to determine how the location of ventricular arrhythmia presentation influences survival. BACKGROUND: Most studies of cardiac arrest report outcome following out-of-hospital resuscitation. In contrast, there are minimal data on long-term outcome following in-hospital cardiac arrest. METHODS: The AVID Study was a multicenter, randomized comparison of drug and defibrillator strategies to treat life-threatening ventricular arrhythmias. A Registry was maintained of all patients with sustained ventricular arrhythmias at each study site. The present study includes patients who had AVID-eligible arrhythmias, both randomized and not randomized. Patients with in-hospital and out-of-hospital presentations are compared. Data on long-term mortality were obtained through the National Death Index. RESULTS: The unadjusted mortality rates at one- and two-year follow-ups were 23% and 31.1% for patients with in-hospital presentations, and 10.5% and 16.8% for those with out-of-hospital presentations (p < 0.001), respectively. The adjusted mortality rates at one- and two-year follow-ups were 14.8% and 20.9% for patients with in-hospital presentations, and 8.4% and 14.1% for those with out-of-hospital presentations (p < 0.001), respectively. The adjusted long-term relative risk for in-hospital versus out-of-hospital presentation was 1.6 (95% confidence interval [CI] 1.3-1.9). CONCLUSIONS: Compared with patients with out-of-hospital presentations of life-threatening ventricular arrhythmias not due to a reversible cause, patients with in-hospital presentations have a worse long-term prognosis. Because location of ventricular arrhythmia presentation is an independent predictor of long-term outcome, it should be considered as an element of risk stratification and when planning clinical trials.

Aged↗
PubMed1999

Sites on the cytoplasmic region of phospholamban involved in interaction with the calcium-activated ATPase of the sarcoplasmic reticulum.

Proton NMR studies have shown that when a peptide corresponding to the N-terminal region of phospholamban, PLB(1-20), interacts with the Ca2+ATPase of the sarcoplasmic reticulum, SERCA1a, docking involves the whole length of the peptide. Phosphorylation of Ser16 reduced the affinity of the peptide for the pump by predominantly affecting the interaction with the C-terminal residues of PLB(1-20). In the phosphorylated peptide weakened interaction occurs with residues at the N-terminus of PLB(1-20). PLB(1-20) is shown to interact with a peptide corresponding to residues 378-405 located in the cytoplasmic region of SERCA2a and related isoforms. This interaction involves the C-terminal regions of both peptides and corresponds to that affected by phosphorylation. The data provide direct structural evidence for complex formation involving residues 1-20 of PLB. They also suggest that phospholamban residues 1-20 straddle separate segments of the cytoplasmic domain of SERCA with the N-terminus of PLB associated with a region other than that corresponding to SERCA2a(378-405).

Amino Acid Sequence↗
PubMed1999

[Low level of residual renal function in the initial month and high transport characteristic as important causes of peritoneal dialysis failure].

OBJECTIVE: To evaluate what kind of patients was at high risk on peritoneal dialysis (PD) treatment. METHODS: 96 patients on PD for (23.1 +/- 10.0) months were studied. The patients were divided into two groups. Group A: patients (25) who died or switched to hemodialysis because of cardiovascular disease, malnutrition, ultrafiltration inefficiency, hydrothora, relapsing peritonitis, etc. Group B: stable PD patients (71) up to now. Age, body surface area (BSA) and dialysate fill volume (DV) were not different between the two groups. The nutritional status, dialysis adequacy, peritoneal membrane transport characteristics, and residual renal function (RRF) in the initial month of dialysis were compared. Patient survival rate was studied by Kaplan-Meier method. RESULTS: It was demonstrated that Kt/V and Ccr in group A were lower than those in group B (P < 0.05). Meanwhile, RRF was significantly different between the two groups; patients with better RRF (> or = 2 ml/min) had higher survival. The percentage of high transporters in group A was greater than in group B. CONCLUSION: Higher clearance in the initial month of dialysis seems to keep PD successful. PD failure maybe related to high transport characteristic and its treatment modality is DAPD. Hemodialysis will be a better choice when RRF is very low as water balance is poorly controlled by DAPD.

Adolescent↗
PubMed1999

[An experimental study on effect of methazolamide on decreasing intraocular pressure in rabbits].

OBJECTIVE: To study the therapeutic effect of methazolamide on glaucoma. METHODS: Various doses of methazolamide were orally administered in rabbits, their effects on high intraocular pressures and on recovery of low intraocular pressures were observed. RESULTS: The high intraocular pressures were significantly decreased and the maintenance of low intraocular pressure was significantly prolonged by the oral administration of 40, 20, 10 mg/kg of methazolamide. A dose-effect relationship that is the reduction of intraocular pressure increases with the increase of the dosage administration of methazolamide could be observed. CONCLUSION: This study indicates that methazolamide might play an effective therapeutic role in glaucoma.

Animals↗
PubMed1999

[The analysis of pathological changes of cardiac conduction system in 54 cases of cardiac sudden deaths].

OBJECTIVE: To elucidate the exact cause of death in cases of cardiac sudden deaths. METHODS: Sampling of cardiac conduction system (CCS) designed by the research group was adopted. The CCS of 120 cases died of cardiac sudden deaths were collected for routine histological examination. RESULTS: In 54 out of 120 cases, the causes of death were attributed to lesions present in the CCS, and 85.2% of them were young adults. The peak age range was from 20 - 30. Much more in males (6.7:1). The pathological changes in CCS include: inflammation (46.2%), fatty infiltration, hypertrophic cardiomyopathy associated with CCS changes; hemorrhage, developmental anomalies, fibrosis and tumors. CONCLUSION: The pathological changes of CCS are relatively common, as the cause of sudden deaths. Which is considered to be the pathological basis of the unstable cardiac electric potentials and arrhythmia. This study recommended the necessity of routine examination on CCS in cases of sudden deaths.

Adult↗
PubMed1999

[The meaning of the expression of PCNA and c-erbB-2 in the hyperplasia of laryngeal epithelium].

OBJECTIVE: This study was performed to examine the relationship between PCNA and c-erbB-2 expression and histological diagnosis. METHOD: The percentages of PCNA-positive nuclei (PCNA index) were evaluated in biopsies of 10 with epithelial simple hyperplasia, 26 with dysplasia and 30 with squamous carcinoma by immunohistochemical staining. RESULT: The PCNA indices were 6.64%, 29.36% and 62.67% respectively. There were significant statistic correlation between these indices and their histological gradies of lesions (P < 0.01). C-erbB-2 was not positive in all of dysplastic lesion and weak in carcinoma (20%). CONCLUSION: The PCNA activity in dysplastic lesions of laryngeal premalignancis is higher than that in simple hyperplastic lesions but lower than that in carcinoma. The severe dysplasia with high PCNA indices should be treated clinically as the early invasive carcinom. The method should be regarded as a useful adjunct to traditional histological techniques with allowing more objective grading of epithelial hyperplastic lesions of larynx. There was no relationship between c-erbB-2 expression and histolotical diagnosis of hyperplastic lesions.

Adult↗
PubMed1998

Affinity purification of the Ca-ATPase from cardiac sarcoplasmic reticulum membranes.

We report the isolation of the functional form of the Ca-ATPase from porcine cardiac sarcoplasmic reticulum (SR) membranes, taking advantage of the ability of this enzyme to bind to the nucleotide site affinity dye, Reactive Red 120. Conditions that optimize the solubility and functional stability of the cardiac Ca-ATPase in detergent during the purification procedure are essential to its recovery. The purified Ca-ATPase migrates as a single band on Coomassie blue-stained polyacrylamide gels and exhibits high specific activity (2.5 IU at 25 degreesC) and functional stability. Similar enrichment of the Ca-ATPase estimated from either relative amounts of the 100-kDa protein band on polyacrylamide gels or steady-state concentrations of phosphorylated enzyme intermediate (E-P) demonstrate that neither nonfunctional Ca-ATPases nor non-Ca-ATPase proteins migrating with an apparent molecular weight of 100 kDa constitute a significant fraction of these preparations. Steady-state levels of E-P are 1.3 and 8.6 nmol/mg protein, respectively, for native cardiac SR membranes and the final purified fraction. These values, in comparison to the maximum value (9.1 nmol/mg) for the 110-kDa protein, agree well with estimates of total Ca-ATPase abundance from gel densitometry for both preparations and indicate full site reactivity, i.e., one phosphorylation site for each 110-kDa cardiac Ca-ATPase polypeptide chain.

Animals↗
PubMed1998

Microencapsulation of rat islets prolongs xenograft survival in diabetic mice.

OBJECTIVE: To protect the transplanted islets from the host's immune system by means of immunoexclusion membranes. METHODS: Rat islets were isolated from Wistar rat pancreas by ductal collagenase distention, stationary digestion, and finally with the aid of dextran gradient separation. Then the islets were encapsulated in alginate-polylysine-alginate (APA) semipermeable membranes. RESULTS: In vitro studies demonstrated that encapsulated islets secreted insulin in response to glucose challenge for at least 8 weeks, which was similar to free islets. In vivo studies showed that 15 streptozotocin (STZ)-induced diabetic mice were transplanted intraperitoneally with 1000 encapsulated islets without immunosuppression. Diabetes was reversed within 3 days, and the mice remained normoglycemic for up to 160 days, with a mean xenograft survival time of 126 days. The encapsulated islets had a significantly greater effect than unencapsulated islets, which functioned for less than 8 days. CONCLUSIONS: Encapsulation of pancreatic islets in semipermeable membranes can effectively prolong xenograft survival without immunosuppression in an animal model.

Animals↗
PubMed1998

[Morphological observations of tumors in the cardiac conduction system].

OBJECTIVE: To investigate the incidence of tumors in the cardiac conduction system (CCS) and to study their relation to sudden deaths. METHODS: The CCS from 149 cases of sudden death without extracardiac cause of deaths and those from 737 cases of non-cardiac death were sampled using technique designed by the authors. Routine histological examinations were carried out. RESULTS: Tumors in the CCS were found in 12 cases (1.35%). Another case with tumor in the CCS was found in a specimen received for consultation. Of these 13 tumors, 10 were primary benign tumors affecting the CCS, 3 were metastatic tumors. The benign tumors included fibroma, hemangioma, lipomatous hypertrophy of the atrial septum, mesothelioma and rhabdomyoma. 8 of the 10 cases were located in the SAN or AVN. All the metastatic tumors were in the SAN. Of the 13 cases, 3 died suddenly. CONCLUSION: Tumors in the CCS are the smallest tumors which can cause sudden death.

Adolescent↗
PubMed1998

[Chemical constituents of Phyllanthus urinaria L. and its antiviral activity against hepatitis B virus].

Studies on the chemical constituents of Phyllanthus urinaria and its antiviral activity against hepatitis B virus were completed. Eleven compounds have been isolated. Two of them are new compounds methyl ester dehydrochebulic acid and methyl brevifolin carboxylate. Antiviral experiments on HBsAg in vitro and liver damage caused by CCl4 have shown that. Phyllanthus urinaria possesses antiviral activities against HBV.

Animals↗
PubMed1998

[Retrocaval ureter].

OBJECTIVE: To improve the diagnosis of retrocaval ureter. METHOD: 20 cases of retrocaval ureter with an average age of 33.4 years were reported. The diagnosis of this disease depends on urography and retrograde ureterography. Operation was the principal treatment. Ureter orthopedics and reduction were performed in 19 cases of type 1 (low loop) except one case of type II (high loop). After removing 3 - 4 cm retrocaval ureter with pathological changes, we anastomosed the ureter without tension and regained its normal anatomic position. RESULT: B-ultrasound and excretory urography showed no stenosis and improvement of hydronephrosis. CONCLUSION: Ureter orthopedics and reduction are ideal for the treatment of retrocaval ureter.

Adolescent↗
PubMed1998

[Metabolic transformation of (-)-clausenamide in rat liver microsomes].

The metabolic transformation of (-)-clausenamide, isolated from the leaves of Clausena lansium (Lour.) Skeels, was studied in vitro with phenobarbital-induced rat liver microsomal incubate containing the NADPH-generating system. The constitution of the incubation system was optimized and a RP-HPLC-DAD method was developed for the on-line analysis of (-)-clausenamide and its metabolites. The major metabolites were isolated and purified by silica gel column chromatography, preparative TLC and HPLC and their structures were determined as 6-OH clausenamide (CM1) and 5-OH clausenamide (CM2) by 1HNMR and MS.

Animals↗