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Shu-Qin Li

Publications and source records attributed to Shu-Qin Li.

16 recordsLinked to original sources
PubMed2007

The upregulation of glial glutamate transporter-1 participates in the induction of brain ischemic tolerance in rats.

Glial glutamate transporter-1 (GLT-1) plays an essential role in removing glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. To explore whether GLT-1 plays a role in the acquisition of brain ischemic tolerance (BIT) induced by cerebral ischemic preconditioning (CIP), the present study was undertaken to observe in vivo changes in the expression of GLT-1 and glial fibrillary acidic protein (GFAP) in the CA1 hippocampus during the induction of BIT, and the effect of dihydrokainate (DHK), an inhibitor of GLT-1, on the acquisition of BIT in rats. Immunohistochemistry for GFAP showed that the processes of astrocytes were prolonged after a CIP 2 days before the lethal ischemic insult, which could protect pyramidal neurons in the CA1 hippocampus against delayed neuronal death induced normally by lethal ischemic insult. The prolonged processes extended into the area between the pyramidal neurons and tightly surrounded them. These changes made the pyramidal layer look like a 'shape grid'. Simultaneously, the prolonged and extended processes showed a great deal of GLT-1. Western blotting analysis showed significant upregulation of GLT-1 expression after the CIP, especially when it was administered 2 days before the subsequent lethal ischemic insult. Neuropathological evaluation by thionin staining showed that DHK dose-dependently blocked the protective role of CIP against delayed neuronal death induced normally by lethal brain ischemia. It might be concluded that the surrounding of pyramidal neurons by astrocytes and upregulation of GLT-1 induced by CIP played an important role in the acquisition of the BIT induced by CIP.

Animals↗
PubMed2006

Nitric oxide participates in the induction of brain ischemic tolerance via activating ERK1/2 signaling pathways.

The present study was undertaken to observe in vivo changes of expression and phosphorylation of ERK1/2 proteins during brain ischemic preconditioning and effects of inhibiting generation of nitric oxide (NO) on the changes to determine the role of ERKs in the involvement of NO participating in the acquired tolerance. Fifty-five Wistar rats were used. Brain ischemic preconditioning was performed with four-vessel occlusion for 3 min. Total ERK1/2 proteins and phospho-ERK1/2 in the CA1 hippocampus were assayed with Western immunoblot. Total ERK1/2 proteins did not change in period from 5 min to 5 days of reperfusion after preconditioning stimulus. While the level of phospho-ERK1/2 increased obviously to 223, 237, 300, 385 and 254% of sham level at times of 5 min, 2 h, 1, 3 and 5 days after preconditioning stimulus, respectively (P < 0.01). Administration of L-NAME, an inhibitor of NO synthase, 30 min prior to preconditioning stimulus failed to induce change in total ERK1/2 proteins (P > 0.05). However, phospho-ERK1/2 increased only to 138 and 176% of sham level at 2 h and 3 days after preconditioning stimulus, respectively, when animals were pretreated with L-NAME. The magnitudes of the increase were obviously low compared with those (237 and 385%) in animals untreated with L-NAME at corresponding time points (P < 0.01), which indicated that phosphorylation of ERK1/2 normally induced by preconditioning stimulus was blocked apparently by administration of L-NAME. The results suggested that phosphorylation of ERK1/2, rather than synthesis of ERK1/2 proteins, was promoted in brain ischemic preconditioning, and that the promotion was partly mediated by NO signal pathway.

Adaptation, Physiological↗
PubMed2006

Limb ischemic preconditioning induces brain ischemic tolerance via p38 MAPK.

It has been reported that limb ischemic preconditioning (LIP) could induce brain ischemic tolerance. In the present study, we investigated the role of p38 MAPK in the induction of brain ischemic tolerance by observing expression of phosphorylated p38 (p-p38) MAPK in the hippocampus after LIP and the effect of p38 MAPK inhibitor SB 203580 on the protection of LIP against delayed neuronal death (DND) in the CA1 hippocampus induced normally by brain ischemic insult. The results of Flow cytometry and Western blotting showed that expression of p-p38 MAPK initially increased at 6 h after LIP compared with sham group in the CA1 hippocampus. The increases reached peak at 12 h and lasted to 24 h after LIP. Expression of p-p38 MAPK was also increased in the CA3/dentate gyrus (DG) regions after LIP, but the beginning and peaking times were 1 and 3 days after LIP, which were relatively later than those in the CA1. Histological evaluation showed that LIP protected the CA1 hippocampal pyramidal neurons against DND induced by global brain ischemic insult for 8 min, suggesting the occurrence of brain ischemic tolerance. Pretreatment with SB 203580 at 30 min before LIP effectively blocked the ischemic tolerance induced by LIP. Together, it could be concluded that activation of p38 MAPK played an important role in the brain ischemic tolerance induced by LIP, and that components of the p38 MAPK cascade might be targets to modify neuronal survival in ischemic tolerance.

Analysis of Variance↗
PubMed2006

[Effects of L-arginine on the expression of insulin-like growth factors and insulin-like growth factor binding protein 3 in rats with intrauterine growth retardation].

OBJECTIVE: Intrauterine growth retardation (IUGR) may contribute to the disorder of development of fetal brains. L-arginine has been known to be effective in blood vessel distension and improving the blood circulation of placentas. Recent studies have shown that L-arginine can ameliorate the placental hypoxia and improve the development of fetus. This study aimed to explore the effects of L-arginine on the expression of insulin-like growth factor (IGF)-I, IGF-II, IGF binding protein-3(IGFBP3)and IGF-I mRNA in brains of IUGR rats and the possible mechanisms of L-arginine. METHODS: Thirty-six pregnant rats were randomly assigned into four groups: Control, Model, Low dose L-arginine (100 mg/kg) and High-dose L-arginine (200 mg/kg L-arginine) groups (n=9 each). IUGR was induced by passive smoking in rats from the last three groups. L-arginine was administered for the last two groups between days 8 and 20 of gestation. On day 21 of gestation, the pup rats were delivered by cesarean section. The levels of IGF-I, IGF-II and IGFBP3 in the brains of pup rats were measured by enzyme-linked immunoadsordent assay (ELISA) and the expression of IGF-I mRNA was detected by fluorescence quantitative PCR (FQ-PCR). RESULTS: The levels of IGF-I, IGF-II and IGF-I mRNA expression in the Model group were significantly lower than in the Control group, with the IGF-I levels of 0.789 +/- 0.062 ng/mg vs 0.947 +/- 0.042 ng/mg, the IGF-II levels of 0.270 +/- 0.020 ng/mg vs 0.374 +/- 0.015 ng/mg and the IGF-I mRNA expression of (13.12 +/- 1.39) x 10(4) cps/mug RNA vs (21.28 +/- 3.54) x 10(4) cps/mug RNA (P < 0.01). In contrast, the IGFBP3 levels in the Model group were significantly higher than in the Control group (0.253 +/- 0.011 ng/mg vs 0.089 +/- 0.015 ng/mg; P < 0.01). Low or high dose L-arginine treatment increased significantly the IGF-I levels from 0.789 +/- 0.062 ng/mg (Model group) to 0.937 +/- 0.067 ng/mg (low dose group) or 0.858 +/- 0.077 ng/mg (high dose group), the IGF-II levels from 0.270 +/- 0.020 ng/mg (Model group) to 0.318 +/- 0.018 ng/mg (low dose group) or 0.354 +/- 0.021 ng/mg (high dose group) and the IGF-I mRNA expression from (13.12 +/- 1.39) x 10(4) cps/mug RNA (Model group) to (19.24 +/- 2.48) x 10(4) cps/mug RNA (low dose group) or (17.35 +/- 2.30) x 10(4) cps/mug RNA (high dose group) (P < 0.01). The IGFBP3 levels were significantly reduced after low or high dose L-arginine treatment (0.132 +/- 0.006 ng/mg or 0.146 +/- 0.009 ng/mg) compared with those of the Model group (0.253 +/- 0.011 ng/mg) ( P < 0.01). CONCLUSIONS: L-arginine can increase the levels of IGF-I and IGF-II and the IGF-I mRNA expression, and decrease the IGFBP3 level in the brain of rats with IUGR induced by passive smoking, thereby offering protective effects against IUGR.

Animals↗
PubMed2005

Construction of a novel Shigella live-vector strain co-expressing CS3 and LTB/STm of enterotoxigenic E.coli.

AIM: To construct and evaluate a polyvalent recombinant vaccine strain Shigella flexneri 2a T32 against enterotoxigenic E.coli (ETEC). METHODS: By using a host-plasmid balanced lethal system based on asd gene, a polyvalent recombinant strain was constructed to highly express CS3 and regularly express fusion enterotoxin of LTB subunit and mutant ST (LTB/STm) in a vaccine strain Shigella flexneri 2a T32 with specific deletion of asd gene. Fimbria CS3 was observed by immunofluorescence and electron microscopy assay. The security of LTB/STm was examined by ileal loop assay and suckling mouse assay. To evaluate this new candidate vaccine, it was compared with a previous vaccine strain in plasmid and protein level, growth assay and immunogenicity in Balb/c mice. RESULTS: The newly constructed vaccine expressed CS3 and grew better than the previously constructed vaccine except for the lower expression of LTB/STm. Serum IgG and mucosal IgA against CS3, LTB, ST, and host lipopolysaccharide (LPS) were produced after immunization of Balb/c mice by oral route with the new strain. The titers were not significantly different from the Balb/c mice with the previous strain. CONCLUSION: This novel candidate diarrheal vaccine can effectively induce serum and mucosal antibody responses against ETEC and Shigella.

Animals↗
PubMed2004

Antigen epitope of Helicobacter pylori vacuolating cytotoxin A.

AIM: To construct and select antigen epitopes of vacuolating cytotoxin A (VacA) for nontoxic VacA vaccine against Helicobacter pylori (H pylori ) infection. METHODS: Eleven VacA epitopes were predicted according to VacA antigenic bioinformatics. Three candidates of VacA epitope were constructed through different combined epitopes. The candidate was linked with E. coli heat-labile enterotoxin B (LTB) by a linker of 7 amino acids, and cloned into plasmid pQE-60 in which fusion LTB-VacA epitope was efficiently expressed. To test the antigencity of the candidate, 6 BALB/c mice were treated with the fusion LTB-VacA epitope through intraperitoneal injection. To explore the ability of inhibiting the toxicity of VacA,cantiserum against the candidate was used to counteract VacA that induced HeLa cells to produce cell vacuoles in vitro. RESULTS: Serum IgG against the candidate was induced in the BALB/c mice. In vitro, the three antisera against the candidate efficiently counteracted the toxicity of VacA, and decreased the number of cell vacuoles by 14.17%, 20.20% and 30.41% respectively. CONCLUSION: Two of the three candidates, LZ-VacA1and LZ-VacA2, can be used to further study the mechanism of vacuolating toxicity of VacA, and to construct nontoxic VacA vaccine against H pylori infection.

Amino Acid Sequence↗
PubMed2004

[MK-801 inhibits formalin-induced cyclooxygenase-2 expression in the dorsal horn of the spinal cord in rats].

To investigate the effect of N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 on the formalin-induced cyclooxygenase-2 (COX-2) expression in the dorsal horn of the rat spinal cord. Forty-eight male Sprague-Dawley rats were divided into 4 groups: control, formalin, formalin+normal saline (NS) and formalin+MK-801 groups. Rats in formalin, formalin+NS and formalin+MK-801 groups were subcutaneously injected with 0.2 ml 5% formalin into the plantar surface of the right hind paw. NS or MK-801 solution (10 microl) was intrathecally injected under transient ether anesthesia 15 min prior to the formalin injection in the formalin+NS and formalin+MK-801 groups, respectively. Flinch reflex was measured within 1 h after the formalin injection and expression of COX-2 in the dorsal horn of the L(5) segment of the spinal cord was assayed 24 h after the formalin injection using immunohistochemistry. Formalin evoked a biphasic flinch reflex. MK-801 produced a limited effect on the flinch reflex of phase 1, but produced significant and dose-dependent suppression on the flinch reflex of phase 2. The number and immunostaining density, shown by grey degree which was inversely proportional to the immunostaining density, of immunoreactive soma in the superficial (mainly I-II) and deep (IV-VI) laminae of the L(5) spinal cord in formalin and formalin+NS groups increased significantly, in contrast to those in the control group (p<0.01). The number and immunostaining density of immunoreactive soma decreased significantly in formalin+MK-801 group, in comparison with the formalin+NS group (p<0.05). The degree of the decrease was proportional to the dosage of MK-801 used. In addition, there were some immunoreactive processes especially in the superficial laminae, which extended as a continuous band across the dorsal horn after the formalin injection. Change in immunostaining density of the processes after administration of MK-801 was similar to that in the immunoreactive soma. The results showed that intrathecal injection of MK-801 significantly inhibited the increase of COX-2 expression in the spinal dorsal horn induced by the formalin injection in a dose-dependent manner, suggesting that the activation of NMDA receptor is one of the mechanisms for the formalin-induced increase of COX-2 expression in the spinal dorsal horn.

Animals↗
PubMed2004

[Expression of human mu-opioid receptor cDNA in CHO cell].

Opioid receptor, is classified into three subtypes, mu, kappa and delta, with the mu-type receptor plays important roles in opioid analgesia and opioid addiction. The cDNA encoding mu-type receptor was obtained by RT-PCR from human brain RNA and was cloned into pcDNA3.1(+). The resultant recombinant plasmid pcDNAMORs were transfected into CHO cells by liposome. After PCR identification, the positive clone were treated with agonist and antiagonist were tested for their competence of signal transduction. CHO cells that contained mu-opioid receptor in the expression vector pcDNA3.1(+) acquired naloxone-blockable high-affinity specific binding of morphine and DAMGO. The concentration of cAMP in CHO cells transfected with pcDNAMOR was reduced after binding to morphine and DAMGO, and increased after binding naloxone. These results indicate that the mu-type receptor expreesd on the CHO cell has similar biological property as the nature receptor. The availability of these specific cell lines will facilitate the drug development and promote our understanding the mechanism underlying opiate addiction.

Animals↗
PubMed2003

[Intrathecal injection of Sar9, Met(O2)11-substance P, neurokinin-1 receptor agonist, increases nitric oxide synthase expression and nitric oxide production in the rat spinal cord].

In the spinal cord, nitric oxide (NO) pathway is involved in pain and hyperalgesia, and nitric oxide synthase (NOS) expression and NO production are upregulated following several noxious and lesion stimuli. However, the mechanism of the increases is yet not well understood. The present study was designed to address the question of whether substance P (SP) released in the spinal cord enhances NOS expression and NO production of the spinal cord in rats. [Sar(9), Met(O2)(11)]-substance P (Sar-SP), a neurokinin-1 (NK-1) receptor agonist, was administered by intrathecal injection via L(5)-L(6) intervertebral space to induce nociception. The pain threshold was determined by hot water induced tail flick test. NOS expression of the L(5) segment of the spinal cord was determined using NADPH-d histochemical staining. NO production of the lumbar enlargement of the spinal cord was determined by assaying NO3(-) and NO2(-), the end product of NO metabolism, using the method of aqua fortis reduction. We found that (1) intrathecal injection of Sar-SP (6.5 nmol) elicited a characteristic, caudally directed, nociceptive behavioural response consisting of intense biting, licking and scratching episodes. Tail flick test showed decrease in pain threshold. (2) following the behavioural responses, the NOS expression level, including the number and the staining density of the NADPH-d reactive cells, increased in the superficial portion of the dorsal horn (Laminae I-II) and the grey matter surrounding the central canal (LaminaX) of the L(5) segment of the spinal cord after the Sar-SP intrathecal injection. At the same time, NO production in the enlargement of the spinal cord increased. (3) The decreased pain threshold and the increases in NOS expression and NO production could be substantially inhibited by intrathecal injection of [[D-Arg(1), D-Trp(7,9), Leu(11)]-substance P] (spantide) (5 microg), a non-selective antagonist of NK-1 receptor, 5 min prior to the Sar-SP injection. It might be concluded that the release of SP resulted from nociceptive afferents increased NOS expression and NO production of the rat spinal cord.

Animals↗
PubMed2003

[Simultaneous expression of CS3 colonization factor antigen and LT-B/ST fusion enterotoxin antigen of enterotoxigenic Escherichia coli by attenuated Shigella flexneri 2a].

Enterotoxigenic Escherichia coli (ETEC) causes watery dehydrating diarrhea in infants in developing countries, and is the most common cause of travelers diarrhea. It has been known that the colonazition factor antigens (CFAs) and enterotoxins are important virulence factors of ETEC, and these two kinds of proteins should be included in any effective vaccine against ETEC. In this study, a host-plasmid lethal balancing system was constructed based on asd gene in an avirulent strain of S.flexneri to express CS3 antigens and the fusion LT-B/ST enterotoxins of Escherichia coli. Both of these antigens were expressed steadily in the S. flexneri vector without any antibiotic markers. Antibodies against CS3, LT, ST and LPS of Shigella were detected in sera of mice that were immunized with recombinant bacteria either oragastrically (o.g.) or intranasally (i.n.). SIgA against CS3 and enterotoxins were detected simultaneously in feces of mice. This work is helpful for constructing multivalent recombinant vaccine for prevention of bacterial diarrhea.

Animals↗
PubMed2003

[Co-expression of CFA/I and CS6 of Enterotoxigenic Escherichia coli ( ETEC ) in Shigella flexneri 2a T32 Derivative Strain FWL01].

Among the known colonization factors of enterotoxigenic Escherichia coli (ETEC), CFA/I and CS6 (the common antigen in the CFA/IV fimbrial antigens ) are two of the most prevalent fimbriae found in clinical isolates but are never expressed by the same wild-type strains. In this study, CFA/I and CS6 of ETEC were co-expressed in Shigella flexneri 2a T32 derivative strain FWL01 by using a host-plasmid lethal balancing system based on asd gene. The results indicate that the recombinant plasmid carrying CFA/I and CS6 could be stably integrated in FWL01. Expression of the two antigens did not interfere the host growth. The results of immunofluorescence analysis showed that CFA/I and CS6 were localized on the surface of the strain FWL01. In Balb/c mice orally immunized with the recombinant strain, the immune responses against CFA/I and CS6 were observed. Those observations show the feasibility of a multivalent vaccine expressing different fimbrial antigens in attenuated Shigella flexneri.

Animals↗
PubMed2002

Simultaneous expression of CS3 colonization factor antigen and LT-B/ST fusion enterotoxin antigen of enterotoxigenic Escherichia coli by attenuated Salmonella typhimurium.

LT and ST are the main enterotoxins of enterotoxigenic Escherichia coli (ETEC) found in clinical isolates, and CS3 (the common antigen in the CFA/II family of fimbrial antigens) is one of the most prevalent antigens of colonization factors. The genetic determinants encoding CS3 and LT-B/ST fusion toxin were manipulated so that these important antigens are expressed simultaneously in attenuated Salmonella typhimurium oral vaccine strain X4072. These antigens produced by X4072 (pXZL88) could be recognized with monospecific CS3, LT or ST antibodies respectively. The specific antibodies against CS3, LT and ST could be detected. In the sera of immunized mice via oral route with the live bacteria. Significantly, the antibody to ST was able to neutralize the biological activity of native ST. This prototype construct may be proved to be useful in investigating the live vector approach to immunoprophylaxis of ETEC diarrhea disease.

Animals↗
PubMed2001

Expression of Colonization Factor Antigen I of Enterotoxigenic Escherichia coli in Shigella flexneri 2a T32.

A host-plasmid lethal balancing system was constructed based on asd gene in an avirulent strain of S.flexneri to express colonization factor antigen I(CFA-I) of enterotoxigenic Escherichia coli.The results of Western blotting suggested that avirulant strain of S.flexneri Fwl01 expressed CFA-I steadily. Examination of negatively-stained preparation of cultures by electron microscopy showed that S.flexneri Fwl01 carrying the plasmid pZHY21 had thick pili on its surface. Antibodies against CFA-I were decteted in sera of mice immunized with recombinant bacteria either orogastrically (o.g.) or intranasally(i.n.); simultaneously sIgA against CFA-I was also decteted in the intestine. This work is helpful for constructing multivalent reombinant vaccine for prevention of bacterial diarrhea.

Journal Article↗
PubMed2000

Cloning and Secretion Expression of Heat-shock Protein 70 Gene of Helicobacter pylori.

Heat-shock protein 70 gene (hsp70)was obtained by PCR method from Helicobacter pylori chromosomal DNA. Sequencing analysis exhibited that the hsp70 gene isolated from Hp Y(2) was highly homologous with the gene encoded in Helicobacter pylori 26695 and J99, which had been sequenced for complete genome. The hsp70 gene was recombined in vitro with fusion secretion expression vector pMAL-p2 and was transformed into E.coli cells. The E.coli strains, containing hsp70 recombinant plasmid, expressed a 113 kD fusion protein which accounted for 19.4% of the total bacterial periplasm protein after the induction with IPTG for 5 h at 30 degrees. The expressed fusion protein could react specifically with anti-Helicobacter pylori rabbit IgG, as proved by Western blot method.

Journal Article↗
PubMed1999

Cloning and Expression of alpha-Bungarotoxin Gene.

The genetic engineering methods to produce the snake neurotoxin obviously have potential advantages over the traditional methods of extracting neurotoxin from snakes. This work was to study the expression and the feasibility of scaled production of snake neurotoxin in the routine expression systems such as E.coli with the -bungarotoxin as an example. First, on the basis of the reported amino acid sequence of alpha-bungarotoxin, DNA sequence of -bungarotoxin was deduced and four partially complementary oligonucleotide fragments were designed. The coding region of -bungarotoxin was obtained by renaturing the DNA fragments, nick filling-in, ligation and PCR. The coding region of -bungarotoxin was cloned into plasmids pGEX-2T, named pDZ04, and transformed E.coli BL21 in order to study the expression of alpha-bungarotoxin gene. The results of SDS-PAGE analysis showed that the recombinant plasmid pDZ04 could express efficiently in BL21, and the fusion protein took up about 30%-40% of total bacterial protein. Finally, The biological activity of the recombinant alpha-bungarotoxin and the fusion protein was studied with the natural alpha-bungarotoxin purified from the snake venom as control, ELISA results showed that they had similar antigenicity.

Journal Article↗