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Biomedical subjects

Qing Li

Publications and source records attributed to Qing Li.

At least 91 records · Page 5Linked to original sources
PubMed2005

BRE enhances in vivo growth of tumor cells.

Human BRE, a death receptor-associating intracellular protein, attenuates apoptotic response of human and mouse tumor cell lines to death receptor stimuli in vitro. In this report, we addressed whether the in vitro antiapoptotic effect of BRE could impact on tumor growth in vivo. We have shown that the mouse Lewis lung carcinoma D122 stable transfectants of human BRE expression vector developed into local tumor significantly faster than the stable transfectants of empty vector and parental D122, in both the syngeneic C57BL/6 host and nude mice. In vitro growth of the BRE stable transfectants was, however, not accelerated. No significant difference in metastasis between the transfectants and the parental D122 was detected. Thus, overexpression of BRE promotes local tumor growth but not metastasis. We conclude that the enhanced tumor growth is more likely due to the antiapoptotic activity of BRE than any direct effect of the protein on cell proliferation.

Animals↗
PubMed2005

Towards automated 3D finite element modeling of direct fiber reinforced composite dental bridge.

An automated 3D finite element (FE) modeling procedure for direct fiber reinforced dental bridge is established on the basis of computer tomography (CT) scan data. The model presented herein represents a two-unit anterior cantilever bridge that includes a maxillary right incisor as an abutment and a maxillary left incisor as a cantilever pontic bonded by adhesive and reinforced fibers. The study aims at gathering fundamental knowledge for design optimization of this type of innovative composite dental bridges. To promote the automatic level of numerical analysis and computational design of new dental biomaterials, this report pays particular attention to the mathematical modeling, mesh generation, and validation of numerical models. To assess the numerical accuracy and to validate the model established, a convergence test and experimental verification are also presented.

Biocompatible Materials↗
PubMed2005

Activity and stability of laccase in conjugation with chitosan.

Laccase is one of a few enzymes that can directly reduce oxygen into water under ambient conditions, while oxidizing a variety of aromatic compounds. Its conjugation with chitosan generates a pH-sensitive functional biomaterial that changes its solubility in response to pH variation. The molecular conjugation between laccase and chitosan of different molecular mass was investigated with a carbodiimide reaction to understand the mechanism of the enzyme's activity loss during conjugation. With 81-93% laccase being conjugated, a moderate activity loss (16-28% less than the initial activity) was observed in conjugation solution. A second severe activity loss (63-78% less than the conjugated activity) occurred during a cycle of phase change consisting of precipitation, centrifugation and re-dissolution of the enzyme-chitosan conjugates. The chitosan molecular size has little effect on the first moderate activity loss in the conjugation reaction, but visible effect on the substantial activity loss associated with phase change. Small chitosan molecules gave high residual activity. The conjugated laccase exhibited a high stability in the following repeated phase changes and had the same temperature and pH profile as those of free laccase. Compared to free laccase, the conjugated laccase had a similar affinity (Km), but reduced turnover (kcat) that was adversely affected with increase of molecular mass of chitosan.

Biocompatible Materials↗
PubMed2005

Developmental changes induced by graded prenatal systemic hypoxic-ischemic insults in rats.

In infants, a common consequence of systemic perinatal insults is disruption of neonatal brain development. Such insults can cause cerebral palsy, cognitive delay, epilepsy and other chronic neurologic deficits in children. The mechanisms underlying disruption of brain development after perinatal insults are poorly defined. To mimic human systemic insults, a transient prenatal hypoxic-ischemic insult model was developed in rodents. Ischemic animals showed reproducible histological lesions including oligodendrocyte loss, gliosis, and axonal disruption. Ischemic animals displayed persistent postnatal loss of oligodendrocyte lineage cells and cortical neurons, decreased cell proliferation, increased cell death, elevated pro-inflammatory cytokine levels, and impaired motor skills as young adults. Progressive ischemic intervals produced a graded pattern of injury. This systemic rodent prenatal hypoxic-ischemic insult accurately models human perinatal brain injury in several important criteria, including functional association of altered brain development with motor delay, and consequently provides novel insights into the pathogenesis of human perinatal brain insults.

Animals↗
PubMed2005

Effect of pretreatment of food gluten with prolyl endopeptidase on gluten-induced malabsorption in celiac sprue.

BACKGROUND & AIMS: We sought to determine whether prolyl endopeptidase (PEP) treatment of food gluten would obviate the intestinal dysfunction produced by small amounts of dietary gluten supplement in patients with celiac sprue. METHODS: Twenty asymptomatic patients with histologically proven celiac sprue completed a randomized, double-blind, cross-over study involving two 14-day stages. Each patient consumed a low dose of a gluten supplement daily (5 g; equivalent to 1 slice of bread) in 1 stage and gluten pretreated with PEP in the other stage. Patients completed a daily symptom questionnaire and a D-xylose urine excretion and a 72-hour quantitative fecal fat were monitored before and after each stage. RESULTS: Despite clinical remission at baseline, 40% of patients had at least 1 abnormal celiac antibody, 20% had an abnormal urine xylose, and 63% had an abnormal fecal fat test result. There was no difference in symptoms as a function of the type of gluten consumed. In response to gluten not treated with PEP, an appreciable proportion of patients developed malabsorption of fat (7 of 17, 41%) or xylose (8 of 14, 57%). When the gluten was pretreated with PEP, fat malabsorption was avoided in 5 of 7 and xylose malabsorption in 4 of 8 of these same patients. CONCLUSIONS: A significant proportion of asymptomatic patients with celiac sprue have abnormal celiac antibodies and fat or carbohydrate malabsorption. Pretreatment of gluten with PEP avoided the development of fat or carbohydrate malabsorption in the majority of those patients who developed fat or carbohydrate malabsorption after a 2-week gluten challenge.

Adult↗
PubMed2005

Effect of electric foot shock and psychological stress on activities of murine splenic natural killer and lymphokine-activated killer cells, cytotoxic T lymphocytes, natural killer receptors and mRNA transcripts for granzymes and perforin.

To explore the mechanism of stress-induced inhibition of natural killer (NK) activity, female C57BL/6 mice were stimulated by electric foot shock and psychological stress for 7 days consecutively. The shocked mice received scrambled, uncontrollable, inescapable 0.6 mA electric shocks in a communication box 120 times during 60 min. The mice in the psychological stress group were put into the communication box without electric foot shock. The plasma corticosterone level in both stressed groups was significantly higher than that in controls on days 1, 3, 5 and 7 and showed the highest level on day 3 in the foot shock stress. According to these results, therefore, we investigated the effect of stress on immunological function on day 3, and measured body weight, weight of the spleen, number of splenocytes, splenic NK, lymphokine-activated killer (LAK) and cytotoxic T lymphocyte (CTL) activities, NK receptors, and mRNA transcripts for granzymes A and B and perforin in splenocytes. The NK, LAK and CTL activities, and NK receptors in mice with both types of stress were significantly decreased compared to those of the control mice, but the decreases were greater in the foot-shocked mice than in the psychological-stress mice. The mRNA transcripts for granzyme A and perforin were significantly decreased only in the foot-shocked mice. On the other hand, the foot-shock stress increased granzyme B. The above findings suggest that stress induced inhibition of NK, LAK and CTL activities partially via affecting NK receptors, granzymes and perforin.

Animals↗
PubMed2005

Histidine enhances carbamazepine action against seizures and improves spatial memory deficits induced by chronic transauricular kindling in rats.

AIM: To investigate whether histidine can enhance the anticonvulsant efficacy of carbamazepine (CBZ) and simultaneously improve the spatial memory impairment induced by transauricular kindled seizures in Sprague-Dawley rats. METHODS: Chronic transauricular kindling was induced by repeated application of initially subconvulsive electrical stimulation through ear-clip electrodes once every 24 h until the occurrence of 3 consecutive clonic-tonic seizures. An 8-arm radial maze (4 arms baited) was used to measure spatial memory, and histamine and gamma-amino-butyric acid levels were measured by high performance liquid chromatography (HPLC). RESULTS: Chronic transauricular kindling produced a significant impairment of spatial memory and a marked decrease in histamine content in the hypothalamus, the brainstem, and the hippocampus. Injection of histidine (1000 mg/kg or 1500 mg/kg, ip) significantly inhibited transauricular kindled seizures. Injection of histidine at lower doses (200 mg/kg or 500 mg/kg, ip) had no appreciable anticonvulsant effect when administered alone, whereas it significantly potentiated the protective effects of CBZ against kindled seizures. CBZ had no ameliorative effect on memory deficit, but, in contrast, histidine (200 mg/kg or 500 mg/kg, ip) alone or co-administered with CBZ significantly ameliorated the memory deficits induced by the seizures. CONCLUSION: Chronic transauricular kindling is a very useful animal model for evaluating memory deficits associated with epilepsy, and histidine has both a potentiate effect on the anticonvulsant efficacy of CBZ and an ameliorative effect on the spatial memory deficits induced in this model. Histidine at a specific dosage range might serve as a beneficial adjuvant for the clinical treatment of epilepsy, especially when accompanied by impaired spatial memory.

Animals↗
PubMed2005

September 2004: a 6-year-old girl with headache and stiff neck.

Free-living amebas in the genera Naegleria, Acanthamoeba and Balamuthia are known to cause CNS infections. Here we report a case of fatal granulomatous amebic meningoencephalitis (GAE) caused by Balamuthia mandrillaris in a 6-year-old previously healthy girl who presented with headache and stiff neck. She was treated medically for brain abscess after a CT scan identified a ring-enhancing lesion in the right temporo-parietal area. A brain biopsy showed necrosis and granulomatous inflammation. Subsequently, multiple new lesions appeared in the brain bilaterally. A second brain biopsy revealed viable amebic trophozoites that were most abundant in perivascular spaces, accompanied by neutrophils, macrophages and eosinophils. Immunofluorescence study confirmed the amoeba as Balamuthia mandrillaris. This case demonstrates that making diagnosis of GAE pre-mortem requires a high index of suspicion. Amebic infection should be included in the differential diagnosis of any granulomatous lesion in CNS; and careful search for amebic parasites should be carried out especially when necrosis predominates in the pathological material.

Amebiasis↗
PubMed2005

Hemolysis of erythrocytes by granulysin-derived peptides but not by granulysin.

Granulysin, a 9-kDa protein localized in human cytolytic T lymphocytes and natural killer cell granules, is cytolytic against tumors and microbes but not against red blood cells. Synthetic peptides corresponding to the central region of granulysin recapitulate the lytic activity of the intact molecule, and some peptides cause hemolysis of red blood cells. Peptides in which cysteine residues were replaced by serine maintain their activity against microbes but lose activity against human cells, suggesting their potential as antibiotics. Studies were undertaken to determine the mechanism of resistance of red blood cells to granulysin and sensitivity to a subset of granulysin-derived peptides. Granulysin lyses immature reticulocytes, which have mitochondria, but not red blood cells. Granulysin lyses U937 cells but not U937 cells lacking mitochondrial DNA and a functional respiratory chain (U937rho(o) degrees cells), further demonstrating the requirement of intact mitochondria for granulysin-mediated death. Peptide G8, which corresponds to helix 2/loop 2/helix 3, lyses red blood cells, while peptide G9, which is identical except that the cysteine residues were replaced by serine, does not lyse red blood cells. Granulysin peptide-induced hemolysis is markedly inhibited by an anion transporter inhibitor and by Na(+), K(+), and Ca(2+) channel blockers but not by Na(+)/K(+) pump, cotransport, or Cl(-) channel blockers. Although recombinant granulysin and G9 peptide do not induce hemolysis, they both competitively inhibit G8-induced hemolysis. The finding that some derivatives of granulysin are hemolytic may have important implications for the design of granulysin-based antimicrobial therapeutics.

Amino Acid Sequence↗
PubMed2005

Insomnia as a sequela of sarin toxicity several years after exposure in Tokyo subway trains.

More than 5,000 passengers on Tokyo subway trains were injured with toxic chemicals including the nerve gas "sarin" on March 20, 1995. The purpose of this study was to identify the effect of sarin exposure on insomnia in a cross-sectional study. A self-administered questionnaire concerning sleep-related items was distributed to victims of sarin exposure in October and November, 2003. Questionnaires were completed by 161 of the 163 participants (98.8%), who were selected from 1,500 subjects. Among them, the authors selected 75 women 30 to 69 years of age. Control participants were collected from inhabitants living in Maebachi City, Gunma Prefecture, Japan. For the younger exposed group (under 50 yr. of age), percentages of poor sleep, difficulty falling asleep, intermittent awakening, early morning awakening, a feeling of light overnight sleep, and insomnia were significantly higher than those for the control group. In contrast, the older exposed group (ages 50 to 69 years) had significantly higher prevalence of poor sleep, a feeling of light overnight sleep, and early morning awakening for the exposed group when compared with the control group. The high prevalence of insomnia and insomnia-related factors for victims especially under 50 years of age suggests a need for research on sleep quality after sarin exposure. Although posttraumatic stress disorder is assumed to be a psychological effect of exposure to a toxic substance, a cause-and-effect relationship has not been established.

Adult↗
PubMed2005

Involvement of taurine in penicillin-induced epilepsy and anti-convulsion of acupuncture: a preliminary report.

The potential role of taurine on epilepsy and acupuncture anti-convulsion was addressed in the present study. Epilepsy was induced by micro-injection of penicillin into hippocampus of Wistar rats. Taurine was applied by intraperitioneal (i.p.) injection. Electro-acupuncture (EA) was performed on acupoints of DU 20 "Bai Hui" and DU 16 "Feng Fu" along DU channel. Epileptic grades were evaluated by electro-encephalography (EEG) and behavior score. We featured the dose-response relationship between taurine-treated epilepsy and epilepsy-only subjects, detected the effect of exogenous taurine on epilepsy and acupuncture treatment, and investigated taurine transporter immuno-activity in hippocampus using immunohistochemistry. It was found that: 1), taurine had a significant antiepileptic effect as applied at i.p. 20 mg/kg, 40mg/kg, 80mg/kg, especially at 40mg/kg in the rat model of penicillin-induced seizure. Animals were improved by one to three Racine grades in behavior and in frequency and amplitude of EEG. 2), Exogenous taurine enhanced the anti-convulsive effect of EA. Both behavior and EEG were improved in taurine-treated rats. EA inhibited epilepsy. Exogenous taurine improved epilepsy in a synergistic manner to EA. 3), EA increased the concentration of taurine transporter in hippocampus by comparing EA-treated epilepsy with normal control and penicillin only, or EA-treated plus taurine-treated epilepsy with taurine-treated only epilepsy and penicillin only. The resulting data suggested that taurine may play an inhibitory role against epilepsy as an inhibitory amino acid in the central nervous system and EA may inhibit epilepsy via upregulating the concentration of taurine transporter to increase the release of taurine.

Acupuncture Therapy↗
PubMed2005

[Construction of the eukaryotic expression vector pIRES2-EGFP-Axin and its expression in glioma cells].

AIM: To construct the eukaryotic expression vector pIRES2-EGFP-Axin, and to express Axin in C6 glioma cells. METHODS: The Axin gene was amplified by PCR using pCMV5-HA-Axin as a template, and confirmed by DNA sequencing. The eukaryotic expression vector pIRES2-EGFP-Axin was constructed by introducing Axin DNA fragment into the sites of Nhe I and Sal I of pIRES2-EGFP vector. The plasmid was transfected into the C6 cells using lipofectamine. The expressed EGFP was observed under fluorescent microscope and the Axin protein expression was detected by immunostaining using anti-Axin antibody. RESULTS: The eukaryotic expression vector pIRES2-EGFP-Axin was constructed and transfected successfully into C6 glioma cells. The green fluorescence of EGFP was observed in the plasma and nuclei of transfected cells, and Axin protein was only found in the plasma. CONCLUSION: The recombinant expression vector pIRES2-EGFP-Axin was constructed, and the EGFP and Axin gene could be co-expressed in the C6 cells. This study laid a foundation for the further research of the function of Axin in cell differentiation, growth and tumorigenesis.

Animals↗
PubMed2005

[Transplantation of mouse bone marrow mesenchymal stem cells into the xenogeneic testis].

OBJECTIVE: To study transplantation of mouse bone marrow mesenchymal stem cells (MSCs) into the xenogeneic testis. METHODS: (1) The tibias and femurs were dissected from 5-6-week-old mice. The marrow in the tibias and femurs was flushed out with medium. MSCs were isolated, cultured and purified in vitro by Percoll density gradient centrifugation combined with adherent method. (2) MSCs of the third generation were adopted and marked with Hoechest33342 for observation, and then made into cell-suspending fluid. (3) The marked MSCs were transplanted into the testis of the xenogeneic mouse by testis net injection. The biopsies of the testis tissues were carried out at different time and made into frost slices at three sites for observation. RESULTS: (1) A lot of purified MSCs were obtained at the third generation. (2) The nucleoli of the marked MSCs showed light-yellow under the fluoroscope. (3) Xenogeneic transplantation of mouse bone marrow MSCs by testis net injection was successful, without immunoreaction. On the 1 st day after transplantation, MSCs only concentratively distributed in the medial slices, the nucleoli being light-yellow; On the 1 st and 3 rd day, MSCs dispersively distributed in the medial slices; On the 6th, 9th and 12th day, MSCs presented in all the slices of the three sites, some ranging tubally; On the 15th and 18th day, the fluorescence of MSCs weakened; On the 21 st day, the fluorescence of MSCs disappeared. CONCLUSION: Transplantation of mouse bone marrow MSCs into the xenogeneic testis by testis net injection is effective and feasible, without immunoreaction. MSCs can survive after transplantation.

Animals↗
PubMed2005

[Prokaryotic expression of BirA enzyme and identification of the bioactivity of expressed product].

AIM: To construct the expression vector of biotin-protein ligase (BirA enzyme) gene and express the BirA enzyme with bioactivity in E.coli BL-21 (DE3). METHODS: The BirA gene was amplified from E.coli genome by PCR and cloned into pGEX-4T-2 to construct the recombinant plasmid pGEX-BirA. After being verified by DNA sequencing, the fusion protein was expressed under IPTG induction in the E.coli BL-21 (DE3). The expressed product was purified through Glutathione-agarose chromatography column. The enzyme activity of the expressed product was identified by ELISA and Western blot. RESULTS: The recombinant prokaryotic expression vector pGEX-BirA was constructed and the fusion protein GST-BirA was expressed successfully. The results of ELISA and Western blot showed that the purified BirA enzyme biotinylated HLA-A2 peptide complex. CONCLUSION: BirA enzyme with bioactivity is prepared successfully, which can be used for studying the interaction between protein and protein.

Biotinylation↗
PubMed2005

[Antisense oligonucleotide targeting survivin induces apoptosis of renal clear-cell carcinoma cells and enhances their sensitivity to epirubicin in vitro].

OBJECTIVE: To investigate the effect of antisense oligonucleotide (ASODN) targeting survivin on the apoptosis and proliferation of renal cancer cell line 786-O and enhancement of its sensitivity to epirubicin. METHODS: ASODN targeting survivin was designed and constructed. Cultured cells were divided into 6 groups: control group, liposome group, sense oligonucleotide (SODN) group, 600 nmol/L ASODN group, and 600 nmol/L ASODN combined with epirubicin group. After transfected for 24 h, cultured cells were harvested to carry on the next tests. Cell morphological changes were examined by transmission electron microscopy. Survivin protein was detected by immunohistochemical method. Apoptosis index (AI) and proliferation index (PI) were examined by flow cytometry. RESULTS: Morphological abnormalities of cells were observed in ASODN transfected groups. Expression of survivin in ASODN groups were significantly decreased compared with that in the control group, liposomes group and SODN group. AI of ASODN groups was significantly higher than that in other groups. PI of ASODN groups was significantly lower than that in other groups. The PI of ASODN combined with epirubicin group was (35.7 +/- 1.67)%, but (9.3 +/- 0.34)% or (8.5 +/- 0.21)% in liposomes group or SODN group that had combined with epirubicin. The ASODN group achieved the strongest effects to enhance apoptosis in comparison with control group (P < 0.05), while SODN did not cause statistically significant change (P > 0.05). CONCLUSION: The expression of survivin protein in the renal clear cell carcinoma cell line 786-O is downregulated by survivin ASODN. ASODN targeting survivin induces apoptosis and inhibits proliferation of 786-O cells. Inhibition of survivin enhances sensitivity of 786-O to epirubicin.

Antibiotics, Antineoplastic↗