Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 217 records · Page 12Linked to original sources

PubMed2001

[Evaluation the pathological diagnostic values of koilocyte in condyloma acuminatum].

OBJECTIVE: To evaluate the histological diagnostic values of koilocyte in histopathologic diagnosis of condyloma acuminatum. METHODS: Koilocyte was served as diagnostic criteria to scan 2 063 biopsies and compared the results with "goldan standard" of histopathologic diagnosis of condyloma acuminatum. RESULTS: Using koilocyte as diagnostic standard to diagnose condyloma acuminatum, the sensitivity and specificity were 77.93% and 95.26%, with positive predictive value 97.25%, negative predictive value 66.70%, positive likelihood rate 81.81, negative likelihood rate 23.17, under diagnostic rate 22.07%, misdiagnostic rate 4.74%. CONCLUSION: The koilocyte was proved to be one of classical histopathological morphologic features of human papillomavirus infection and other virus infection which served one of the most important histopathological markers for diagnosis of condyloma acuminatum, but not the only one.

Biopsy↗

PubMed2001

[A study on the epidemiology of Helicobacter pyroli infection among immigrants in Three Gorges area].

OBJECTIVE: To investigate the epidemiologic features of Helicobacter pyroli (Hp) sero-prevalence rates among immigrants in Three Gorges area. METHODS: Enzyme labelled immuno-sorbant-assay was used to determine the Hp prevalence rate. A case-control study including 1 600 immigrants as cases and 1 600 non-immigrants as controls was carried out to explore the features of Hp infection in Three Gorges area. RESULTS: The prevalence rate of Hp in immigrant area was 67.50% higher than 53.19% that of Hp in non-immigrant (chi(2) = 13.40, P < 0.01). Rate of Hp infection was highest in infants than in children, increasing with age to clearly show a positive correlation between age and Hp prevalence rate (r = 0.62, P < 0.01). However, there was no marked sex difference in Hp infection rates in the immigrant area. Same results were also presented in the non-immigrant area. Hp prevalence rates were different which related to the stages of flooding. It is 89.17% in the area of first stage, while in second and third stages of flooding, the rates were 76.40% and 62.20% respectively. CONCLUSION: Preliminary result indicated that Hp infection rate of immigrant area was higher than that of non-immigrant area. It appeared that living condition, environment, education condition might possibly have played important role in Hp prevalence. It is more important to prevent from infected children. Further study with respect to Hp prevalence rate was necessary when immigration is completed and the standard of living improved.

Adolescent↗

PubMed2001

[Multivariate analysis of prognostic factors in Philadelphia chromosome-positive chronic granulocytic leukemia].

OBJECTIVE: To investigate the prognostic factors of the patients with Philadelphia chromosome-positive chronic granulocytic leukemia (CGL). METHODS: Clinical and laboratory parameters of 209 CGL patients at diagnosis were analyzed in relation to survival. COX regression analysis were used to identify the statistically significant prognostic factors. RESULTS: The median survival time was 57 (3 - 179) months, and 5 year survival rate was 48%. From the COX regression model, the four main poor prognostic factors were as follows: percentage of bone marrow blasts (>or= 0.04), percentage of peripheral blood blasts and promyelocytes and presence of erythroid precursors in peripheral blood. According to the prognostic scores, three groups of CGL were identified. The low-risk group was with a median survival time of 76 months, the intermediate-risk group with 56 months, and the high-risk group with 31.5 months (P < 0.01). The 5 year survival rate was 70.42%, 46.30% and 18.18% (P < 0.01), respectively. CONCLUSIONS: A prognostic scoring system suitable for Chinese CGL patients was proposed.

Adolescent↗

PubMed2001

[Dynamic monitoring of Ph positive cells during early post-transplant period in chronic granulocytic leukemia by interphase FISH].

OBJECTIVE: To assess the effectiveness of transplantation and observe the kinetics of residual leukemic cells during early post-transplantation period in chronic granulocytic leukemia (CGL). METHODS: Ten normal controls, seven untreated CGL patients and eleven CGL patients after allogeneic bone marrow transplantation (allo-BMT) or peripheral blood stem cell transplantation (PBSCT) were studied by interphase fluorescence in situ hybridization (I-FISH) with the FITC fluorescein labeled BCR probe. Conventional cytogenetic analysis (CCA) and reverse transcriptase-polymerase chain reaction (RT-PCR) were also employed. RESULTS: The normal cutoff was defined as less than 6.68% (x +/- 3s) from the analysis of normal controls. The reproduciblity of FISH method was confirmed by serial dilutions by mixing Ph positive cells and normal cells. Forty specimens from 11 CGL patients at 1 week to 6 years post-BMT were investigated after PBSCT and the results showed that (1) FISH and RT-PCR could accurately evaluate Ph (+) cells during early transplantation period (within one month), but RT-PCR was more sensitive in six months after BMT. (2) Residual Ph (+) cells tended to be linear decreasing with the time after transplantation and fell in normal range in most samples three months later. The mean time of normaligation was 57 days (20 to 170 days). (3) One case relapsed and received a second transplantation. FISH presented more precise data for predicting relapse as compared to CCA and RT-PCR. CONCLUSIONS: I-FISH as a useful tool can not only offer more precise assessment of residual leukemic cells compared with CCA and RT-PCR, but also provide dynamic monitoring during early post-BMT period to evaluate the transplantation outcome and predict relapse.

Adult↗

PubMed2001

Differential responses of regional vascular beds to local injection of agmatine in rats.

In 66 anaesthetized rats, the effects of local injection of agmatine on femoral, renal, and mesenteric vascular beds were investigated respectively by constant flow perfusion method. The results are as follows. (1) Agmatine (0.1, 0.5, 1 mg/kg) increased the perfusion pressure (PP) of femoral vascular bed in a dose dependent manner. The effect of agmatine (1 mg/kg) was completely blocked by pretreatment with idazoxan (0.5 mg/kg), an antagonist for imidazoline receptors (IR) and alpha(2)-adrenergic receptors (alpha(2)-AR), and yohimbine (1 mg/kg), a selective alpha(2)-AR antagonist. (2) Agmatine also increased the PP of renal vascular bed in a dose-dependent manner, and agmatine at high dose (1 mg/kg) caused a biphasic increase of PP in renal vascular bed. Idazoxan blocked these effects completely, while yohimbine led the agmatine induced effect to a decrease in the PP of renal vascular bed. (3) Agmatine decreased the PP of mesenteric vascular bed in a dose-dependent manner, an effect which was completely blocked by idazoxan, but unaffected by yohimbine. From the results obtained, it is concluded that agmatine differentially affects the vascular tone in the femoral, renal, and mesenteric vascular beds.

Agmatine↗

PubMed2001

[A study of the acting mechanism of aspirin for resistance to oxidative damage].

OBJECTIVE: To explore the mechanism of aspirin for resistance to oxidative damage in endothelial cells. METHODS: Using cultured endothelial cells, we measured the levels of aspirin induced ferritin expression on resistance to hydrogen peroxide toxicity toward cells in the presence of the iron chelator desferrioxamine added to FeCl3. RESULTS: Aspirin at low concentration (0.1 mmol/L) induced significant increase of ferritin expression in a time- and concentration-dependent fashion up to 25% over basal levels(P < 0.05). Preincubating the cells for 8 h with aspirin (0.1 mmol/L) reduced lactate dehydrogenase(LDH) release rate by 50%, toxicity reduction by 40%, and significant decrease of malondialdehyde (MDA) production. Aspirin induced cytoprotection from H2O2 damage was also in a concentration- and time-dependent fashion. However, in the presence of the iron chelator desferrioxamine, aspirin enhanced ferritin synthesis was abrogated, in contrast, FeCl3 increased aspirin induced ferritin synthesis in cells. CONCLUSION: The study suggested that the antioxidation of aspirin was brought into action by affecting the cellular iron metabolism pathway to induce ferritin synthesis.

Antioxidants↗

PubMed2001

[Effects of fluid shear stress on PGE2 synthesis of primary osteoblast-like cells in rats].

OBJECTIVE: The purpose of this study is to study the function of PGE2 during the signal transduction in which fluid shear stress regulates the proliferation and differentiation of osteoblast-like cells. METHODS: The isolated rat primary osteoblast-like cells were exposed to fluid shear stress 0.12 mN/cm2 for 5, 10, 15, 30, 60 and 120 minutes respectively in a flow chamber. The release of PGE2 was examined. RESULTS: After exposure to fluid shear stress, the PGE2 synthesis of rat primary osteoblast-like cells increased significantly (P < 0.01) when compared with the control. After 10 minutes, the release of PGE2 began to increase significantly (P < 0.01) and the effect was maximal after 60 minutes (P < 0.01). CONCLUSION: PGE2 pathway may be one of the signal-transduction pathways which can transduce the fluid shear stress into osteoblast-like cells and then stimulate the bone remodeling.

Animals↗

PubMed2001

[Effects of selective attention and contralateral acoustic stimulation on latency of distortion product otoacoustic emissions].

OBJECTIVE: To investigate the effects of selective attention and contralateral acoustic stimulation on latency of distortion product otoacoustic emissions. METHOD: Latency of DPOAE was recorded in 30 ears of 15 normal subjects with and without visual attention task, contralateral acoustic stimulation and combination of both forms of stimulus. RESULT: No significant change was observed in three form of stimulus. CONCLUSION: The effects of selective attention and contralateral acoustic stimulation on latency of DPOAE have to be further studied.

Acoustic Stimulation↗

PubMed2001

[Plasma autoantibodies to heat shock proteins in idiopathic sensorineural hearing loss].

OBJECTIVE: To identify the specificity of autoantibodies to heat shock proteins in idiopathic sensorineural hearing loss (ISNHL) and to evaluate the existence of autoantibodies. METHOD: Plasma samples were obtained from patients with ISNHL (n = 41), systemic lupus erythematosus (n = 22), and normal controls (n = 30). Plasma autoantibodies to heat shock proteins (HSPs) were detected by Western blot using purified recombinant human HSP27, HSP60, HSP71 HSP90 alpha and HSP90 beta as antigen respectively. RESULT: In the ISNHL, the incidence of plasma autoantibodies to recombinant human HSP27, HSP60, HSP71, HSP90 alpha and HSP90 beta were 12.1%, 7.3%, 51.2%, 4.8% and 0% respectively. The incidence of autoantibody to HSP71 was significantly greater than that in systemic lupus erythematosus and in normal controls (P < 0.01). CONCLUSION: These results indicated that the autoantibody to HSP71 was main autoantibodies to HSPS in ISNHL and its presence might serve as a marker for an autoimmune etiology of these patients' hearing loss.

Adult↗

PubMed2001

[Inhibition of ATP-activated current by met-Enk in isolated DRG neurons of the rat].

The present study aimed to explore modulation of ATP-activated currents (I(ATP)) by met-Enk in rat DRG neurons. I(ATP) was recorded using the whole-cell patch clamp technique. The majority of the neurons examined responded to ATP (90.0 percent;, 45/50) with inward currents. In the 45 ATP sensitive neurons three kinds of responses to application of met-Enk were distinguished: (l) inward currents (29/45), (2) outward currents (9/45), and (3) no effect (7/45). Pretreatment with met-Enk (10(-9)~10(-5) mol/L) suppressed I(ATP) (10(-4) mol/L) in 29 neurons responding to met-Enk with inward currents. The inhibition by met-Enk of I(ATP) could be blocked by naloxone (10(-7) mol/L) in a concentration-dependent manner. Met-Enk of 10(-9), 10(-8), 10(-7), 10(-6) and 10(-5) mol/L suppressed I(ATP) by l3.2+/-5.4 percent; (n=5); 39.2+/-8.6 percent; (n=8), 54.l+/-8.6 percent; (n=8),43.3+/-7.9 percent; (n=7) and 43.l+/-7.9 percent; (n=7) (mean+/-MSE), respectively. A comparison of concentration - response relations of ATP with and without preapplication of met-Enk indicated that after pretreatment with met-Enk (10(-7) mol/L) the curve shifted downward markedly with a decrease of 25 percent; of the maximum value of I(ATP) and unchanged K(d) value. The suppression of I(ATP) by met-Enk was reversed as evidenced by intracellular dialysis of H-9 by using the repatch technique. Taken together, it is suggested that the inhibition by met-Enk of I(ATP) is caused by activation of opiate receptor, which eventually results in phosphorylation of ATP receptor, mediated by modulation of G protein coupling and intracellular signal transduction.

Adenosine Triphosphate↗

PubMed2001

[Subtotal laryngectomy reconstructed by platysma myocutaneous flaps].

OBJECTIVE: To study the feasibility, surgical techniques and the results of laryngeal function preservation during subtotal laryngectomy in laryngeal carcinoma. METHODS: A retrospective review was made of 13 patients treated by subtotal laryngectomy and laryngeal reconstruction from 1991 to 1996. Eleven patients were male and 2 were female. The age ranged from 46 to 72 years, with a mean of 53.25. All cases were of stage IV. The essence of this operation is to reconstruct the new larynx with two platysma myocutaneous flaps following subtotal laryngectomy. RESULTS: The success rate of voice rehabilitation was 100%. Among them, the acceptability rating scores in 11 cases were 7 and the intelligibility scores ranged from 95% to 98%. The other two cases had acceptability 5 and intelligibility form 90% to 94%. The three-year survival rate was 84.6% (11/13), 5-year survival rate was 76.9% (10/13). CONCLUSION: This form of laryngeal reconstruction in subtotal laryngectomy is helpful to restore laryngeal function and decrease the rate of total laryngectomy. The procedure is easy, safe and applicable to patients treated by subtotal laryngectomy.

Aged↗

PubMed2001

[Establishment and biological characteristics of cisplatin resistant cell line from human tongue squamous cell carcinoma Tca8113].

OBJECTIVE: To establish a CDDP-resistant cell line from human tongue squamous cell carcinoma cell line Tca8113 and to study the characteristics of this cell line. METHODS: The concentration of CDDP added to Tca8113 cells was increased gradually and the chemotherapeutic drug was added continually, which was to induce the CDDP resistance in Tca8113 cells. The doubling time of Tca8113/CDDP cell line and the oncogenicity of this cell line in nude mice indicated its change on CDDP resistance. The sensibility to drugs of the cell line was assayed by MTT method. DNA fragmentation was detected by electrophoresis. Immunocytochemistry was utilized to examine the expression of P-gp and GST-pi. RESULTS: Tca8113 /CDDP was established and the cells grew steadily in 10 micromol/L CDDP medium. The Tca8113/CDDP cells were also resistant to Vm-26, BLM, VDS, E-ADM, Taxol and other drugs in different degrees. The doubling time of the cells was 29.9 hours and after a month it changed to 16.7 hours. When inoculated in nude mice, the cells showed the typical features of squamous cell carcinoma ultra-structurally and pathologically. Agarose gel electrophoresis of DNA from Tca8113 cells treated with CDDP revealed "ladder"pattern, which was the symbol of apoptosis, but there was no "ladder" in Tca8113/CDDP. The expression of P-gp and GST-pi in Tca8113/CDDP was much higher than that in Tca8113, which was the proof of the up-regulating translation of MDR-1 mRNA. CONCLUSION: CDDP induced Tca8113 cells resistance, and resistant cell line Tca8113/CDDP was established. The multi-drug resistance of Tca8113/CDDP cells were related to the GSH/GST system.

English Abstract↗

PubMed2000

Hypoxia inhibits G1/S transition through regulation of p27 expression.

Mammalian cellular responses to hypoxia include adaptive metabolic changes and a G1 cell cycle arrest. Although transcriptional regulation of metabolic genes by the hypoxia-induced transcription factor (HIF-1) has been established, the mechanism for the hypoxia-induced G1 arrest is not known. By using genetically defined primary wild-type murine embryo fibroblasts and those nullizygous for regulators of the G1/S checkpoint, we observed that the retinoblastoma protein is essential for the G1/S hypoxia-induced checkpoint, whereas p53 and p21 are not required. In addition, we found that the cyclin-dependent kinase inhibitor p27 is induced by hypoxia, thereby inhibiting CDK2 activity and forestalling S phase entry through retinoblastoma protein hypophosphorylation. Reduction or absence of p27 abrogated the hypoxia-induced G1 checkpoint, suggesting that it is a key regulator of G1/S transition in hypoxic cells. Intriguingly, hypoxic induction of p27 appears to be transcriptional and through an HIF-1-independent region of its proximal promoter. This demonstration of the molecular mechanism of hypoxia-induced G1/S regulation provides insight into a fundamental response of mammalian cells to low oxygen tension.

Animals↗

PubMed2000

Familial hypertrophic cardiomyopathy mutations in the regulatory light chains of myosin affect their structure, Ca2+ binding, and phosphorylation.

The effect of the familial hypertrophic cardiomyopathy mutations, A13T, F18L, E22K, R58Q, and P95A, found in the regulatory light chains of human cardiac myosin has been investigated. The results demonstrate that E22K and R58Q, located in the immediate extension of the helices flanking the regulatory light chain Ca(2+) binding site, had dramatically altered Ca(2+) binding properties. The K(Ca) value for E22K was decreased by approximately 17-fold compared with the wild-type light chain, and the R58Q mutant did not bind Ca(2+). Interestingly, Ca(2+) binding to the R58Q mutant was restored upon phosphorylation, whereas the E22K mutant could not be phosphorylated. In addition, the alpha-helical content of phosphorylated R58Q greatly increased with Ca(2+) binding. The A13T mutation, located near the phosphorylation site (Ser-15) of the human cardiac regulatory light chain, had 3-fold lower K(Ca) than wild-type light chain, whereas phosphorylation of this mutant increased the Ca(2+) affinity 6-fold. Whereas phosphorylation of wild-type light chain decreased its Ca(2+) affinity, the opposite was true for A13T. The alpha-helical content of the A13T mutant returned to the level of wild-type light chain upon phosphorylation. The phosphorylation and Ca(2+) binding properties of the regulatory light chain of human cardiac myosin are important for physiological function, and alteration any of these could contribute to the development of hypertrophic cardiomyopathy.

Amino Acid Sequence↗

PubMed2000

Selectivity equivalence of poly(ethylene glycol) stationary phases for gas chromatography.

The solvation parameter model is used to study differences in selectivity for poly(ethylene glycol) stationary phases for packed column (Carbowax 20M) and fused-silica, open-tubular column (HP-20M, AT-Wax, HP-INNOWax and DB-FFAP) gas chromatography. All phases are dipolar, strongly hydrogen-bond basic with no hydrogen-bond acidity and of moderate cohesion. No two phases are exactly alike, however, and selectivity differences identified with cavity formation and dispersion interactions, n- and pi-electron pair interactions, dipole-type interactions and hydrogen-bond interactions are quantified by differences in the system constants at a fixed temperature where retention occurs solely by gas-liquid partitioning. The system constants vary linearly with temperature over the range 60-140 degrees C (except for n- and pi-electron pair interactions which are temperature invariant) facilitating a general comparison of the importance of temperature on selectivity differences for compared phases. From a mechanistic point of view it is demonstrated that selectivity differences can result from chemical differences between the poly(ethylene glycol) stationary phases and from differences in the relative contribution of interfacial adsorption to the retention mechanism. The latter depends on both system properties and solute characteristics.

Chromatography, Gas↗

PubMed2000

Prevention of cisplatin-DNA adduct repair and potentiation of cisplatin-induced apoptosis in ovarian carcinoma cells by proteasome inhibitors.

Histones H2A and H2B are known to be reversibly post-translationally modified by ubiquitination. We previously observed in cultured tumor cells that proteasome inhibition stabilizes polyubiquitinated proteins, depletes unconjugated ubiquitin, and thereby promotes the deubiquitination of nucleosomal histones in chromatin. Provocative indirect evidence suggests that histone ubiquitination/deubiquitination cycles alter chromatin structure, which may limit accessibility of DNA repair proteins to damaged sites. In the present study, we focused on the relationship between the ubiquitination status of histone H2A, the structure of chromatin, and the efficiency of nucleotide excision repair (NER) of cisplatin-DNA adducts in human ovarian carcinoma cells exposed to the antitumor drug cisplatin. Pretreating cells with the proteasome inhibitor lactacystin (LC) or N-acetyl-leucyl-leucyl-norleucinal (ALLnL) induced deubiquitination of ubiquitinated histone H2A (uH2A) and concomitantly promoted chromatin condensation, increased the extent of cisplatin-DNA adducts, and diminished NER-dependent repair of cisplatin-DNA lesions, compared with control cells treated with cisplatin alone. Both proteasome inhibitors also prevented the increase in ERCC-1 mRNA expression that occurs in cells exposed to cisplatin. Cells treated with the combination of ALLnL and cisplatin underwent apoptosis, as indicated by caspase-dependent poly(ADP-ribose) polymerase (PARP) cleavage, more quickly than cells treated with either agent alone. Additionally, the combination of ALLnL and cisplatin potently increased p53 levels in cell lysates and stimulated the binding of p53 to chromatin. Together, these observations suggest that proteasome inhibition may be exploited therapeutically for its potential to sensitize ovarian tumor cells to cisplatin.

Acetylcysteine↗

PubMed2000

Determination of proteins at nanogram levels based on their enhancement effects of Rayleigh light scattering on dibromomethylchlorophosphonazo.

A new Rayleigh light scattering (RLS) assay of protein was conducted in this paper. At the optimum pH conditions, and in the presence of Tween-20, the weak RLS of dibromomethylchlorophosphonazo (DBM-CPA) can be enhanced greatly by the addition of proteins. Based on this, the reactions of DBM-CPA and proteins were studied. A new quantitative determination method for proteins has been developed. The method is simple, practical and relatively free from interference from coexisting substances, as well as much more sensitive (the dynamic ranges of 0.065-40.05 microg ml(-1) and detection limit of 30 ng ml(-1) for bovine serum albumin (BSA)) than most of the existing assays. The determination results of human body serum samples are identical to those by the CBB method, with relative S.D. of six determination of 0.5-2.2%.

Blood Proteins↗

PubMed2000

Reduction in the density and expression, but not G-protein coupling, of serotonin receptors (5-HT1A) in 5-HT transporter knock-out mice: gender and brain region differences.

The aim of the present study was to investigate the mechanisms underlying the desensitization of 5-HT(1A) receptors in the dorsal raphe and hypothalamus of serotonin (5-HT) transporter knock-out mice (5-HTT -/-). The density of 5-HT(1A) receptors in the dorsal raphe was reduced in both male and female 5-HTT -/- mice. This reduction was more extensive in female than in male 5-HTT -/- mice. 8-OH-DPAT-induced hypothermia was absent in female 5-HTT -/- and markedly attenuated in 5-HTT +/- mice. The density of 5-HT(1A) receptors also was decreased significantly in several nuclei of the hypothalamus, amygdala, and septum of female 5-HTT -/- mice. 5-HT(1A) receptor mRNA was reduced significantly in the dorsal raphe region, but not in the hypothalamus or hippocampus, of female 5-HTT +/- and 5-HTT -/- mice. G-protein coupling to 5-HT(1A) receptors and G-protein levels in most brain regions were not reduced significantly, except that G(o) and G(i1) proteins were reduced modestly in the midbrain of 5-HTT -/- mice. These data suggest that the desensitization of 5-HT(1A) receptors in 5-HTT -/- mice may be attributable to a reduction in the density of 5-HT(1A) receptors. This reduction is brain region-specific and more extensive in the female mice. The reduction in the density of 5-HT(1A) receptors may be mediated partly by reduction in the gene expression of 5-HT(1A) receptors in the dorsal raphe, but also by other mechanisms in the hypothalamus of 5-HTT -/- female mice. Finally, alterations in G-protein coupling to 5-HT(1A) receptors are unlikely to be involved in the desensitization of 5-HT(1A) receptors in 5-HTT -/- mice.

Amygdala↗