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Biomedical subjects

J Qiu

Publications and source records attributed to J Qiu.

At least 55 records · Page 3Linked to original sources
PubMed2001

Bcl-xL expression after contusion to the rat spinal cord.

After contusion-derived spinal cord injury, (SCI) there is localized tissue disruption and energy failure that results in early necrosis and delayed apoptosis, events that contribute to chronic central pain in a majority of patients. We assessed the extent of contusion-induced apoptosis of neurons in a known central pain-signaling pathway, the spinothalamic tract (STT), which may be a contributor to SCI-induced pain. We observed the loss of STT cells and localized increase of DNA fragmentation and cytoplasmic histone-DNA complexes, which suggested potential apoptotic changes among STT neurons after SCI. We also showed SCI-associated changes in the expression of the antiapoptotic protein Bcl-xL, especially among STT cells, consistent with the hypothesis that Bcl-xL regulates the extent of apoptosis after SCI. Apoptosis in the injured spinal cord correlated well with prompt decreases in Bcl-xL protein levels and Bcl-xL/Bax protein ratios at the contusion site. We interpret these results as evidence that regulation of Bcl-xL may play a role in neural sparing after spinal injury and pain-signaling function.

Animals↗
PubMed2001

Intra-hepatic expression of scavenger receptor and CD14 and their relationship with local inflammatory responses in endotoxemia in mice.

Our objective was to investigate the expression of scavenger receptor (SR) and CD14 in the liver and their relationship with local anti-inflammatory and proinflammatory responses in endotoxemia in order to uncover the mechanism for the liver to turn into effector organ from defense one at the level of cell receptors in sepsis. Mouse models of endotoxemia of different severity were reproduced by injection of different doses of lipopolysaccharide (LPS) via tail vein. Expression of SR and CD14 in the liver was assayed by immunohistochemistry and was then analyzed with an image analysis system. The levels of TNFalpha, IL-6, IL-4, and IL-10 in liver tissue were determined with ELISA. Expression of SR in the liver in the high-dose group was markedly decreased 1 h after injection of LPS, and also in low- and medium-dose groups at 3 h. The expression of SR in the liver in the three groups was shown to be progressively decreased with the time prolonged. There was significant difference in average optical density (OD) values of SR among the three groups. The expression of CD14 in the liver in the three groups was shown to be significantly increased 1 h after injection of LPS, and much more with the time prolonged. But there was no significant difference in OD values of CD14 among the three groups. The contents of intrahepatic proinflammatory mediators TNFalpha and IL-6 and anti-inflammatory mediators IL-4 and IL-10 were successively significantly increased after injection of LPS. The release of anti-inflammatory mediators was shown to be later than that of proinflammatory mediators. Correlation analysis indicated that there was negative correlation between expression of SR and CD14, and that changes of TNFalpha, IL-6, IL-4, and IL-10 levels in liver tissues were correlated significantly positively with OD values of CD14 and negatively with OD values of SR. Expression of SR in the liver was shown to be progressively decreased, and that of CD14 increased in endotoxemia, which was closely related to the uncontrolled inflammatory response in liver. This might be an important mechanism for the liver to turn into effector organ from defense one in sepsis.

Animals↗
PubMed2001

Effect of sequences of the active-site dipeptides of DsbA and DsbC on in vivo folding of multidisulfide proteins in Escherichia coli.

We have examined the role of the active-site CXXC central dipeptides of DsbA and DsbC in disulfide bond formation and isomerization in the Escherichia coli periplasm. DsbA active-site mutants with a wide range of redox potentials were expressed either from the trc promoter on a multicopy plasmid or from the endogenous dsbA promoter by integration of the respective alleles into the bacterial chromosome. The dsbA alleles gave significant differences in the yield of active murine urokinase, a protein containing 12 disulfides, including some that significantly enhanced urokinase expression over that allowed by wild-type DsbA. No direct correlation between the in vitro redox potential of dsbA variants and the urokinase yield was observed. These results suggest that the active-site CXXC motif of DsbA can play an important role in determining the folding of multidisulfide proteins, in a way that is independent from DsbA's redox potential. However, under aerobic conditions, there was no significant difference among the DsbA mutants with respect to phenotypes depending on the oxidation of proteins with few disulfide bonds. The effect of active-site mutations in the CXXC motif of DsbC on disulfide isomerization in vivo was also examined. A library of DsbC expression plasmids with the active-site dipeptide randomized was screened for mutants that have increased disulfide isomerization activity. A number of DsbC mutants that showed enhanced expression of a variant of human tissue plasminogen activator as well as mouse urokinase were obtained. These DsbC mutants overwhelmingly contained an aromatic residue at the C-terminal position of the dipeptide, whereas the N-terminal residue was more diverse. Collectively, these data indicate that the active sites of the soluble thiol- disulfide oxidoreductases can be modulated to enhance disulfide isomerization and protein folding in the bacterial periplasmic space.

Catalytic Domain↗
PubMed2001

The -10 region is a key promoter specificity determinant for the Bacillus subtilis extracytoplasmic-function sigma factors sigma(X) and sigma(W).

Transcriptional selectivity derives, in large part, from the sequence-specific DNA-binding properties of the sigma subunit of RNA polymerase. There are 17 sigma factors in Bacillus subtilis which, in general, recognize distinct sets of promoters. However, some sigma factors have overlapping promoter selectivity. We hypothesize that the overlap between the regulons activated by the sigma(X) and sigma(W) factors can be explained by overlapping specificity for the -10 region: sigma(X) recognizes -10 elements with the sequence CGAC and sigma(W) recognizes CGTA, while both can potentially recognize CGTC. To test this model, we mutated the sigma(X)-specific autoregulatory site (P(X)), containing the -10 element CGAC, to either CGTC or GCTA. Conversely, the sigma(W) autoregulatory site (P(W)) was altered from CGTA to CGTC or CGAC. Transcriptional analyses, both in vitro and in vivo, indicate that changes to the -10 element are sufficient to switch a promoter from the sigma(X) to the sigma(W) regulon or, conversely, from the sigma(W) to the sigma(X) regulon, but context effects clearly play an important role in determining promoter strength. It seems likely that these subtle differences in promoter selectivity derive from amino acid differences in conserved region 2 of sigma, which contacts the -10 element. However, we were unable to alter promoter selectivity by replacements of two candidate recognition residues in sigma(W).

Amino Acid Sequence↗
PubMed2001

Novel function of Rad27 (FEN-1) in restricting short-sequence recombination.

Saccharomyces cerevisiae mutants lacking the structure-specific nuclease Rad27 display an enhancement in recombination that increases as sequence length decreases, suggesting that Rad27 preferentially restricts recombination between short sequences. Since wild-type alleles of both RAD27 and its human homologue FEN1 complement the elevated short-sequence recombination (SSR) phenotype of a rad27-null mutant, this function may be conserved from yeast to humans. Furthermore, mutant Rad27 and FEN-1 enzymes with partial flap endonuclease activity but without nick-specific exonuclease activity partially complement the SSR phenotype of the rad27-null mutant. This suggests that the endonuclease activity of Rad27 (FEN-1) plays a role in limiting recombination between short sequences in eukaryotic cells.

DNA Repair↗
PubMed2001

Transgenic mice overexpressing leptin accumulate adipose mass at an older, but not younger, age.

Sensitivity to leptin is associated with a normal regulation of the adipose mass, whereas decreased leptin sensitivity results in elevated adipose tissue stores. To address whether the effects of chronic hyperleptinemia are sustained with age, we generated transgenic mice that overexpress leptin under the control of the fat specific aP2 promoter/enhancer. At 6-9 weeks of age, transgenic mice overexpressed 5-fold more human leptin than endogenous mouse levels and had consistently low body weights, with reduced brown and white fat depots characterized by adipocytes either devoid of or containing minute lipid droplets. However, at 33-37 weeks, despite continuous secretion of human leptin, the transgenic mice showed a rebound effect characterized by an increase in body weight, accumulation of adipose mass, and lipid-filled adipocytes. Thus, this mouse model exhibits a two-stage phenotype, with respect to fat accumulation. In addition, plasma glucose, triglycerides, and cholesterol levels were markedly depressed in young, but not older, transgenic mice. A detrimental consequence of early hyperleptinemia was a failure of the transgenic mice to acclimatize to the cold, as a result of depleted fat stores within their brown adipocytes. Cold exposure was tolerated after a 2-week high-fat diet or at an older age when fat depots had naturally accumulated. Treatment of the older transgenic mice with large doses of leptin stimulated weight loss, demonstrating that the leptin pathway still responds to pharmacological levels of leptin. Overall, these studies show that moderate hyperleptinemia in normal mice results in a sensitivity of the adipose mass to leptin at a younger (but not older) age. The mechanisms that lead to the accumulation of fat at an older age remain largely unknown, and this hyperleptinemic mouse model will allow the uncovering of at least some of these mechanisms.

Adipocytes↗
PubMed2001

Leptin-deficient mice backcrossed to the BALB/cJ genetic background have reduced adiposity, enhanced fertility, normal body temperature, and severe diabetes.

A deficiency of leptin synthesis in mice results in a complex phenotype characterized by morbid obesity, diabetes, sterility, and defective thermogenesis. To determine whether the genetic background could alter the pleiotropic effects of leptin deficiency, we backcrossed the ob mutation for 10 generations from the C57BL/6J to the BALB/cJ genetic background. Compared with C57BL/6J ob/ob mice, BALB/cJ ob/ob mice showed at 27 wk of age a 35-40% reduction in body weight attributed to a 60% decrease in white adipose tissue mass. Food intake was not significantly different between the two obese strains, suggesting distinct utilization of energy intake. In the fed state, BALB/cJ ob/ob mice had elevated insulin and triglycerides levels, demonstrating a worsening effect on diabetes. At the reproductive level and in contrast to sterile C57BL/6J ob/ob mice, male and female BALB/cJ ob/ob mice were capable of reproducing after a mating period of 16 and 32 wk, respectively. At thermoneutrality, the body temperature of BALB/cJ ob/ob mice was 2.9 C higher than that of C57BL/6J ob/ob mice, whereas exposure of both groups to 4 C demonstrated a prolonged cold tolerance of BALB/cJ ob/ob mice. These studies show that the abnormalities caused by leptin deficiency can be genetically dissected and separated from each other, suggesting discrete pathways controlled by leptin modifier genes.

Adipose Tissue↗
PubMed2001

[Relationship between the dynamic expression of scavenger receptor on Kupffer cells and endotoxin-induced hepatic injury].

OBJECTIVE: To observe the change of scavenger receptor (SR) expression on Kupffer cells and study its role in pathogenesis of liver injury in mice. METHODS: 1mg/kg or 10 mg/kg of E.Coli 026: B6 LPS was bolus injected via i.a.to reproduce an animal model for this experiment. The change of SR on Kupffer cells was determined with immunohistochemistry. TNF-alpha and IL-6 level in hepatic tissue were assayed using ELISA. RESULTS: The expression of SR on Kupffer cells was aggressively downregulated in a LPS does dependent fashion. TNF-alpha, IL-6 level in hepatic tissue and ALT, TBIL in plasma were significantly negatively correlated with the expression of SR. CONCLUSIONS: With the down-regulation of SR expression on Kupffer cells, the clearance of endotoxin by Kupffer cells is decreased and the activation of Kupffer cells by endotoxin is accordingly enhanced. SR expression is closely related to hepatic injury.

Animals↗
PubMed2001

[The effect of composite Radix Salviae Militiorrhizae injection on myocyte apoptosis in acute myocardial infarction of rabbits].

OBJECTIVE: To study the effect of composite Radix Salviae Militiorrhizae injectiion on myocyte apoptosis in experimental acute myocardial infarction of rabbits. METHODS: The models of acute myocardial infarction were made with rabbits. The method of terminal deoxynucleotidyl transferase mediated dUTP nick end labeling was used to explore myocardial cell apoptosis in different injury area of acute myocardial infarction. The activities of plasma superoxide dismurase and the contents of serum malonic aldehyde were determined. RESULTS: When rabbits were in the condition of acute myocardial infarction, there were myocyte apoptosis in the area of ischemia reperfusion injury and the area of infarction. The number of myocyte apoptosis and the myocyte rate in control group and composite Radix Salviae Militiorrhizae injectiion treated group were higher than in sham-operated group (P < 0.001). In the area of ischemia reperfusion injury the number of myocyte apoptosis and the myocyte rate in composite salvia militiorrhiza-treated group were lower than in control group (P < 0.05). The activity of plasma superoxide dismurase in composite salvia militiorrhiza-treated group was higher than in control group (P < 0.05), but lower than in sham-orerated group (P < 0.001). The content of serum malonic aldehyde in composite Radix Salviae Militiorrhizae injectiion treated group were lower than in control group (P < 0.05), but higher than in sham-operated group (P < 0.01). CONCLUSION: Composite Radix Salviae Militiorrhizae injectiion could reduce the number of myocyte apoptosis in the area of ischemia reperfusion injury, which maybe explained by the increase of the activity of plasma superoxide dismurase and the decrease of the contents of serum malonic aldehyde.

Animals↗
PubMed2001

[Expression of cell adhesion molecule (CD44V6) in thyroid tumors and its significance].

OBJECTIVE: To investigate the expression of the cell adhesion molecule (CD44V6) in thyroid tumor tissue and its relationship with the pathogenesis, development, invasiveness and metastasis of the tumor. METHODS: Immunohistochemistry was applied to examine the expression of CD44V6 in 20 specimens of tissue adjacent to carcinoma, 24 of thyroid adenoma and 64 of thyroid carcinoma (including 30 papillary carcinoma, 26 follicular carcinoma, 2 anaplastic carcinoma and 6 medullary carcinoma). All the specimens were paraffin-embedded. RESULTS: The expression of CD44V6 was observed in 14 specimens of adenomas(58.33%), and 59 of carcinoma (92.19%), but was not detected in the tissue adjacent to carcinoma. The expression of CD44V6 was significantly different between follicular epithelial carcinoma and medullary carcinoma (96.55% vs 50.0%, P < 0.01). The frequency of overexpression of CD44V6 was associated with both invasiveness and lymph node metastasis (P < 0.01), but it had no relation with age, sex and tumor size (P > 0.05). CONCLUSION: It is suggested that CD44V6 will be useful for the diagnosis of thyroid carcinoma and serves as a biological marker for local invasion and lymph node metastasis of thyroid carcinoma.

Adenocarcinoma, Follicular↗
PubMed2001

Relationship between tumor suppressor gene p53 and tumors of adipose tissue.

OBJECTIVE: To investigate the relationship between p53 gene and tumors of adipose tissue at the level of protein and gene. METHODS: Immunohistochemical LSAB, PCR-SSCP and DNA sequencing were used in 82 cases. RESULTS: p53 protein is expressed only in liposarcomas, in which the positive staining rate was 48.08% (25/52). In different subtypes of liposarcomas, the positive staining rate in well differentiated liposarcomas was 30.00% (9/30), which is much lower than that of the poorly differentiated liposarcomas (P < 0.005). Abnormality in the single-stranded DNA pattern was determined in 2 samples (pleomophic liposarcomas) by PCR-SSCP analysis. Missense mutations in exon 8 codon 268 of p53 gene (AAC-->ATC) were detected by DNA sequencing. Another heterozygotic cosense mutation may exist at exon 6 codon 221 of p53 gene (GAG-->GAA). CONCLUSIONS: The data suggest that the p53 protein has a relationship with development, differentiation and malignancy of liposarcoma. Detecting the level of p53 protein expression may be valuable in evaluating the level of differentiation and malignancy of liposarcoma. There appear point mutation on exon 8, 6 of p53 gene.

Genes, p53↗
PubMed2001

[Labyrinthine fistula caused by chronic suppurative otitis media].

OBJECTIVE: To study the clinical feature and surgical management of labyrinthine fistula caused by chronic suppurative otitis media (CSOM). METHOD: A retrospective study of 450 patients with CSOM who underwent radical mastoidectomy between the years 1992 to 1999 in Department of Otolaryngology, Xijing Hospital was conducted. RESULT: 20 patients (4.4%) with labyrinthine fistula caused by CSOM were found. The average history of ear drainage was 22 years, 18 patients (90%) had subjective hearing loss, and 13 patients (65%) had dizziness. The fistula test was positive in 9 patients (45%). 2 patients had anacusis in the affected ear. The preoperative pure tone average for bone conduction thresholds was less than 30 dB in 11 patients, between 31 and 50dB in 3 patients, and more than 51 dB in 4 patients. The ears with a positive fistula test had worse preoperative hearing than those with negative test (P < 0.01). The fistula was detected by CT in 2 of 9 patients. Cholesteatoma was present in 18 patients (90%) and granulation tissue was present in 2 patients (10%). The lateral semicircular canal was the site of labyrinthine fistula. The lesion at the site of fistula was completely removed in 17 patients and exteriorized in the remaining 3. CONCLUSION: There are no reliable methods at present for preoperative diagnosis of labyrinthine fistula, ultimately, the most reliable way to identify a fistula is during surgery. The method of manipulation of labyrinthine fistula is based on the concrete conditions of fistula and patient.

Adult↗
PubMed2001

[Effects of estrogen in the central nervous system].

Estrogen exerts a variety of effects (including electrophysiological, neutrophic and metabolic effects) on neurons in the adult central nervous system. With the many progresses made in the study of estrogen signaling through both genomic and nongenomic pathways, awareness of estrogen's effects on neural function is broadening rapidly. And it also helped people to understand more about the mechanisms by which estrogen regulating GnRH neurons, inducing or maintaining dendritic spine in hippocampus and protecting neurons from a variety of insults. Recently, epidemiological studies have suggested that estrogen, as a hormone replacement therapy in postmenopausal women, may protect against Alzheimer's disease (AD). Findings in these areas demonstrate a role for estrogen that is beyond direct control of reproductive function.

Alzheimer Disease↗
PubMed2001

[The relationship between cell proliferation and apoptosis of vestibular epithelium in the developing guinea pig].

OBJECTIVE: The cell proliferation and apoptosis of vestibular epithelium in normal developing guinea pig were observed to elucidate the relationship and effect between proliferation and apoptosis in developing vestibular epithelium. METHODS: Twenty Guinea pigs with different developing ages were used in our studies. Cell proliferation was detected by proliferation cell nuclear antigen (PCNA) immunocytochemistry while apoptosis was detected by TdT-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) method and transmission electro-microscopy. RESULTS: PCNA staining had been detected in supporting cells but not in hair cells, and the positive cells were gradually decreased with ageing. The differentiated hair cells and supporting cells underwent apoptosis in vestibular sensory epithelium, and TUNEL-positive cells were also markedly decreased with ageing. After birth, TUNEL-positive hair cells were located at the top of ampulla. CONCLUSION: During the development of guinea pig, cell proliferation as well as apoptosis events diminish contemporaneously. The balance between proliferation and apoptosis may regulate the normal number of cells, and is related to guarantee the normal structure and function of inner ear.

Animals↗
PubMed2001

[Transmission properties of Faraday anomalous dispersion optical filter at 532 nm].

In this paper the properties of an excited-state potassium Faraday anomalous dispersion optical filter in potassium vapor with a pump wavelength of 769.90 nm (i.e. 4S1/2-->4P1/2 transition) and a signal wavelength of 532 nm (i.e. 4P1/2-->8S1/2 transition) are calculated and discussed. The filter's transmissions versus the laser pump power and the external magnetic-field are obtained. The theoretical results show the transmission characteristics of the filter are relatively insensitive to the laser pump power and magnetic strength. The laser pump powers require range from 0.8 to 6 mW.cm-2. Our model predicts a peak transmission of 50% and an equivalent band-width of 4 GHz for the filter operating on the 4P1/2<--8S1/2 transition in potassium. The optical filter at 532 nm presented in this paper may be used to detect the practical and important frequency-doubled Nd:YAG laser.

English Abstract↗
PubMed2001

[Study of "living" radical polymerization by FTIR in situ].

Three types of living radical polymerization processes were monitored by means of FTIR spectrometer with handful diamond detector called as Dicomp in situ. It was found that both styrene and styrene/hydroxylpropyl methyacrylate (HPMA) could polymerize according to stable free radical polymerization (SFRP) mechanism in presence of 4-hydroxyl tetramethypiperidiyl-1-oxy(HTEMPO). For styrene/HPMA system, the styrene and HPMA conversion monitored by FTIR were linear with increase of molecular weight, but it gave longer induction period compared with that for St bulk polymerization. It was related to the hydrogen-transfer reaction between the propagating radicals with the end HPMA unit and HTEMPO. Furthermore, This following method in situ could be introduced into monitoring heterogeneous polymerization of styrene during atom transfer radical polymerization (ATRP). The apparent kinetics was found to be about zero order and not 1.0 order, due to propagating on the complex including radicals, CuX and bpy in heterogeneous interface. The polymerization rate will be not related to the St in bulk St phase.

Acrylamides↗