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Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 577 records · Page 32Linked to original sources
PubMed1998

[Inhibitory effects of clonidine on GABA-activated currents in rat DRG neurons].

Whole-cell patch-clamp recordings were performed on neurons from freshly isolated rat dorsal root ganglion (DRG) to investigate modulatory effects of clonidine, an alpha 2-adrenoceptor agonist, on GABA-activated currents. In the majority of the neurons examined (72/75), GABA (10(-6)-10(-3) mol/L) induced a concentration-dependent inward current, which could be blocked by bicuculine (10(-4)-10(-5) mol/L). In 51 out of 72 cells, pretreatment with different dosages of clonidine (10(-8)-10(-4) mol/L) decreased the GABA (10(-4) mol/L)-activated current by 8.5%, 19.0%, 33.4%, 44.4% and 40.3%, respectively, while clonidine itself only induced a slight inward current in a few cells (12/72). The inhibitory action of clonidine blockable by yohimbine (10(-4) mol/L) was voltage-independent and did not change the membrane conductance during the activation of GABAA receptor. Unlike NA, (-)-isoproternol (10(-4)-10(-5) mol/L) exerted no effect on GABA-activated currents. Intracellular application of H-7 (10(-4) mol/L) via micropipette resulted in a significant blockade of clonidine inhibition (19/20) except one cell showing only a slight inhibition (11.2%). The results suggest that the inhibitory effect of clonidine on GABA-activated currents in DRG neurons might involve phosphorylation of GABAA receptor following activation of alpha 2-adrenoceptor through a mechanism of intracellular transduction.

Adrenergic alpha-Agonists↗
PubMed1998

[Inhibition by SKF38393 of GABA-activated currents in rat DRG neurons].

Experiments were performed on neurons freshly isolated from rat DRG using whole-cell patch-clamp techniques. The majority of the neurons examined were sensitive to GABA (60/70) in the concentration range from 10(-6) to 10(-3) mol/L, showing obvious desensitization. In the 60 GABA-sensitive cells, responses induced by selective agonist of dopamine D1 receptor SKF38393 [(+/-) SKF38393HCL] manifested three types: (1) outward current (7/60); (2) inward current (5/60) and (3) no detectable response (48/60). As compared with GABA-activated current, the amplitude of SKF38393-activated current are smaller and showed no apparent desensitization. When the neurons were treated with SKF38393 prior to application of GABA for 30 s, the GABA-activated current in majority of the cells (53/60) was inhibited, while the remaining six showed no effect. The effect of SKF38393 was dose dependent. That is, with SKF38393 at concentration of 10(-7), 10(-6), 10(-5) and 10(-4) mol/L, the GABA-activated current was inhibited by (24.8 +/- 2.6)% (n = 7), (26.8 +/- 1.5)% (n = 7), (35.6 +/- 1.2)% (n = 8) and (45.6 +/- 2.3)% (n = 8) respectively. By intracellular application of 10(-4) mol/L H-7, a potent inhibitor of protein kinase, the inhibitory effect of SKF38393 was abolished completely, a results suggesting that the inhibition by SKF38393 of the GABA-activated current might be a result of intracellular phosphorylation of GABAA receptor.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1998

[Encephalic morphologic changes due to delayed traumatic intracerebral hematoma].

Pathological changes of brain tissues due to delayed traumatic intracerebral hematoma (DTICH) in 6 cases were studied and the mechanism was discussed. It was observed that DTICH went with old brain contusion, traumatic angionecrosis, vasculitis, calcification, encapsulated old focus, proliferation and reactive hypertrophy in glia. Brain contusions and traumatic vessel lesions are important pathological foundations of cerebral hemorrhage and primary causes of DTICH.

Adult↗
PubMed1998

[Effects of glycine and strychnine microinjected into unilateral and bilateral Bötzinger complex on phrenic nerve discharges in rabbits].

The effects of microinjection of glycine and strychnine into unilateral and bilateral Bötzinger complex (Böt. C) on phrenic nerve discharges were observed in 34 urethane anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The results are as follows: (1) microinjection of glycine into unilateral Böt. C induced an increase of respiratory rate and expiratory phrenic nerve discharges; (2) microinjection of glycine into bilateral Böt. C induced non-rhythmic tonic phrenic nerve discharges with an amplitude 40%-70% of control; strychnine could competitively antagonize the effects of glycine; and (3) microinjection of strychnine into bilateral Böt. C induced a decrease of respiratory rate and the amplitude of phrenic nerve discharges, in addition to prolongation of expiratory duration while inspiratory duration remained unchanged. The above results suggest that the Böt. C plays a crucial role in initiating and sustaining expiration.

Animals↗
PubMed1998

[Study on gas exchange of the patients with lung cancer in perioperation].

OBJECTIVE: To study changes of gas exchange in perioperative patients with lung cancer. METHOD: Indices including P/F, a/A, P50O2 and PaCO2 on gas exchange in 68 male patients(50-78 y) with lung cancer were monitored on preoperative day 1 2 3 and postoperative day 7. RESULT: Comparing with preoperation data P/F a/A decreased significantly in 3 days(P < 0.01) and PaCO2 P50O2 increased significantly on the day after operation (P < 0.01), especially in the group of pneumonectomy and abnormal ventilation, hypoxemia measured in preoperation. CONCLUSION: The gas exchange of the patients with lung cancer reduced significantly in postoperative 3 days.

Aged↗
PubMed1998

[Effects of heat, noise, and their combination on plasma atrial natriuretic peptides, cardiodilatin, endogenous digitalis like substance, angiotensin II and endothelin in rats].

Plasma contents of atrial natriuretic peptides (ANP), cardiodilatin (CDD), endogenous digitalis like substance (EDLS), angiotensin II (A II) and endothelin (ET) were determined in rats following exposure to high temperature, noise and a combination of the two. It was found that plasma content of ANP after heat exposure decreased significantly, CDD and A II content after heat or noise exposure increased obviously, ET content decreased significantly after exposure to combined factors. ANP and CDD have the same physiological function and changes. ANP, CDD and A II observed in the present study were considered to be compensatory responses. It is harmful if exposure to high temperature or noise lasts for a long time.

Angiotensin II↗
PubMed1998

Selection of new Epitopes from monovalent displayed phage octapeptide library.

A library of 2 x 10(7) random octapeptides was constructed by use of phagemid-based monovalent phage display system. The randomly synthesized degenerated oligodeoxyribonucleotides (oligos) were fused to the truncated g III (p230-p403). Sequence analysis of 11 randomly chosen clones suggested that the degenerated inserts and its deduced amino acid (aa) sequences are randomly distributed. The library was used to select binding peptides to the monoclonal antibody (mAb) 9E10, which recognizes a continuous decapeptide epitope of denatured human c-myc protein. After four to five rounds of panning, most of the eluted clones could bind to 9E10. Sequence analysis of the selected positive clones indicated that the binding sequences could fall into two classes, one class (clone 1) shares a consensus motif, ISE x x L, with c-myc decapeptide; and the sequences of the other class are entirely different. The binding of both classes to 9E10 could be specifically inhibited by free c-myc decapeptide. The immunogenicity of the phage peptide was further investigated by construction of multivalent displayed phage peptides and immunization of animals with or without adjuvant. ELISA and competitive ELISA showed that anti-serum from both mice and rabbit immunized with either clone could bind to the original antigen, c-myc decapeptide. These results denote that in spite of the dissimilarity of the selected peptides with c-myc decapeptide, they are capable of inducing similar immune respones in vivo, thus actually mimicking the antigen epitope.

Amino Acid Sequence↗
PubMed1998

[Immunologic and clinical study of paraneoplastic limbic encephalitis].

OBJECTIVE: To probe into the pathogenic mechanisms of paraneoplastic limbic encephalitis (PLE) in patients with small cell lung carcinoma (SCLC). METHODS: The indirect immunoperoxidase method and Western blot analysis were used for detecting anti-Hu antibodies in 16 PLE patients associated with SCLC. Autopsy and pathological study were performed on two cases. RESULTS: Eight patients (50%) had anti-Hu antibodies (anti-Hu+) whereas eight patients (50%) no detectable antineuronal antibodies (anti-Hu-). The clinical and laboratory features of PLE and time to diagnosis of SCLC were similar in the anti-Hu+ and anti-Hu- groups. Involvement of other areas of the nervous system in seven (87.5%) patients of the anti-Hu+ group but in only one (12.5)% of the anti-Hu- group (P = 0.012). CONCLUSIONS: The presence of this characteristic neurological disorder strongly suggested that with an accompanying SCLC, existence of anti-Hu autoantibody was in favour of an autoimmune mechanism participating in PLE.

Antibodies, Antinuclear↗
PubMed1998

[Fate of massive retrieved human bone allografts].

OBJECTIVES: To study retrieved massive human allograft specimen after they had been in situ for four to sixty-five months, and to investigate the changes union, bone replacement and degradation of articular cartilage. METHOD: BMP gene expression in the specimen was also studied with in situ hybridization, immunohistochemical methods, and the observations were correlated with the clinical and isotope scan date. RESULT: The union between the allograft and the host was achieved by the formation of an external callus derived from the cortex of the host. New bone replacement took place slowly. Analysis of the articular cartilage revealed evidence that some chondrocytes had survived in non bearing area of the articular. The expression of BMP in the surface of the cortex and united callus was positive 4 months after implantation. But it was negative in the center of cortex after it had been implanted for over 12 months. An external callus formed from the cortex of the host. Some chondrocytes survived in non-bearing area of the articular. Neovasculature penetrated into osteoarticular. CONCLUSION: Bone absorption may be the cause of collapse of articular surface. The results suggest that large allografts in humans are osteo-conductive rather than inductive. Incomplete repair of osteon may be related to slowed replacement of massive human allograft.

Adolescent↗
PubMed1998

[Preoperative radiation plus surgery vs. operation alone for laryngeal carcinoma].

OBJECTIVE: To study the validity of preoperative radiation in improving the survival rate of laryngocarcinoma. METHODS: A prospective randomized clinical trial was conducted with preoperative radiation plus surgery (RS) as one group and surgery alone (SA) as the other group. The ages of the patients were less than 75 years, and the operative types were decided after clinical examination. The patients were divided into SA or RS group by random. Doses of preoperative irradiation was 40 Gy. Three hundred and seventy patients with laryngocarcinoma were treated, 215 in the SA group; 155 in the RS group. All patients were followed up over three years. RESULTS: In SA group, 3 years survival rate was 83.3%, 5-year survival rate 82.6%, 10-year survival rate 80.3%. In RS group, 3-year survival rate was 78.9%, 5-year survival rate 76.4%, 10-year survival rate 68.6%. There is no statistically significant difference in survival rates between the groups (P = 0.1); but, the 10-year survival rate in SA group was better than that in RS group for the stage III and IV supraglottic carcinomas, the former was 73.6% and the latter 63.5% (P = 0.003). The 10-year survival rate for the patients with T3 and T4 supraglottic carcinomas who underwent total laryngectomy in SA group was better than that in RS group. The former was 68% and the latter 50% (P = 0.0001). CONCLUSION: Preoperative radiotherapy with 40 Gy didn't increase the survival rate of laryngeal carcinoma. The 10-year survival of stages III and IV supraglottic carcinoma in combined treatment group was lower than that in the surgery alone group.

Adult↗
PubMed1998

[Study on the interaction of Et2SnCl2(phen) with DNA].

The absorbance, fluorescence and cyclic voltammetric methods as well as agarose gel electrophoresis were used to study the interaction of the antitumor compound Et2SnCl2(phen) with DNA. The results indicate that Et2SnCl2 (phen) mainly reacts electrostatically with the phosphate backbone of DNA. There also exists an intercalation into the double-helix of DNA through the phenanthroline group of Et2SnCl2(phen). At high concentration Et2SnCl2(phen) can cause unwinding of DNA. The molecular action mechanism of Et2SnCl2(phen) with DNA was first proposed.

Animals↗
PubMed1998

[Study on voltammetric behaviour of clozapine and its single-sweep oscillopolarography].

A sensitive reduction peak of clozapine is obtained by single-sweep oscillopolarography in 0.1 mol.L-1 H2SO4 solution. The peak potential is -0.95 V (vs. SCE). The peak current is directly proportional to the concentration of clozapine with a detection limit of 2.0 x 10(-8) mol.L-1. The voltammetric behaviour of clozapine and its mechanism of electrode reaction have been studied by linear-sweep and cyclic voltammetry and pulse polarography etc. The reduction process is irreversible with adsorptive characteristics. The number of electrons transferred n is 2. The electron transfer coefficient alpha is 0.62. Its behaviour obeys Langmuir adsorption isotherm. The adsorption coefficient beta is 1.91 x 10(6) L.mol-1. The energy of adsorption delta G0 = -35.83 kJ.mol-1. The method has been applied to the determination of clozepine in tablet and urine.

Antipsychotic Agents↗
PubMed1998

[SurveilLance on filariasis after its basic elimination in Hunan Province].

AIM: To explore the fluctuation pattern of prevalence and to detect the residual infection in Hunan Province where filariasis had been basically eliminated since 1986. METHODS: Longitudinal surveillance and cross-sectional surveillance were extensively carried out by using parasitological, entomological and serological methods in areas previously endemic for filariasis. RESULTS: In 55 counties, cross-sectional surveillance on filariasis had been executed for 11-19 years. The results showed that microfilaria cases had not been found for 4 years, and filaria larvae had failed to be detected from mosquito vectors for 12 years. Serological surveillance in the population revealed that the mean positive rate of IFAT had dropped from 13.15% in 1987 to 1.06% in 1996, the latter rate being similar to that of the nonendemic area. 6 longitudinal surveillance spots in 5 counties (cities) had been observed for 10-17 years. Annual quantitative blood examination of 11 microfilariemia cases showed that 10 cases became negative in 1-10 years, and the remaining 1 case remained positive at the 14th year. A. sinensis were dissected with no filaria larvae found in 2 surveillance spots of malayan filariasis. Culex quinquefasciatus were dissected with filaria larvae found only in the first to third year, the natural infection rates were 0.38%-1.98% in 4 surveillance spots of bancroftian filariasis. CONCLUSION: Since the basic elimination of filariasis in Hunan Province in 1986, the number of residual microfilariemia cases decreased year after year, suggesting that the transmission of filariasis has been interrupted.

Animals↗
PubMed1998

[The construction of poliovirus chimera and the analysis of its antigenic structure].

The construction of poliovirus chimera is an useful way to investigate the antigenic structure conformation of poliovirus. In this research, the poliovirus chimera containing a piece of antigenic fragment of hepatitis A virus was constructed for analysis of poliovirus antigenic structure conformation. Depending on the characterization of this chimera, the conformation of poliovirus neutralization antigenic site I in VP1 was analyzed, and that the possible influence of hepatitis A virus antigenic fragment inserted to the structure conformation of poliovirus antigen was also investigated.

Animals↗
PubMed1998

[Study of anti-tumor action and influence on immune function of Allium stativum].

Applying mice test on cancer model of S180 and Lewis cancer by using method clystered stomach(oral), observs the Anti-tumor function. Experiments showed that Allium sativum can inhibit tumor growth and Lengthen lift duration of mice, the rate of inhibiting tumor was 74.35% and life lengthening rate were 42.4%, with control grou comparison. There was profund difference between them. Besides, we discoved Allium sativum can raise immune function of mice.

Allium↗