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Biomedical subjects

X Xiao

Publications and source records attributed to X Xiao.

At least 73 records · Page 4Linked to original sources
PubMed2001

[Antibacterial activities of seven commonly used antibiotics to 106 isolated strains of porphyromonas gingivalis in vitro].

OBJECTIVE: Porphyromonas gingivalis (Pg) is one of the main putative pathogens of periodontal disease, especially of adult periodontitis. This in vitro study was aimed at observing the inhibitory activities of 7 commonly used antimicrobical drugs on 106 stains of Pg which isolated from subgingival plaques of sites with adult periodontits. METHODS: Kirby-Bauer paper disk method was used in this study. RESULTS: Pg was highly susceptible to Clindamycin, Sulfamzthoxazole timethoprin, Tetracycline and Cefazolin, the susceptibility rates were 93.4%, 78.3%, 60.4% and 56.6% respectively. CONCLUSION: Majority of the strains of Pg was moderately susceptible to cefalexin and acetylspiramycin, while no strains of Pg was susceptible to Penicillin G. The concentrations of Pg solutions (10(5) CFU/ml, 10(6) CFU/ml and 10(8) CFU/ml) had not influence on the results. This data is helpful for clinically antibiotic selection of periodontal treatment.

Adult↗
PubMed2001

[Randomized controlled trial for the effect of amrinone and aprotinin on proinflammatory cytokine release in patients with prosthetic valve replacement during perioperative period].

OBJECTIVE: To explore the effect of amrinone and aprotinin on whole-body inflammatory response in the patients with prosthetic valve replacement during perioperative period. METHODS: 24 patients undergoing prosthetic valve replacement were randomized to control group (group A, n = 8), aprotinin group (group B, n = 8) and amrinone combined with aprotinin group (group C, n = 8). In the aprotinin group, 3 x 10(6) of aprotinin was added to the priming solution of the extracorporeal circulation (ECC). In the amrinone combined with aprotinin group 3 x 10(6) of aprotinin was added to the priming solution of the ECC and amrinone began with a bolus of 1 mg/kg followed by a maintenance infusion of 8 micrograms/(kg.min). The control group received an equivalent prime volume without aprotinin. Venous blood samples were drawn before the operation, at the end of ECC, 1 hour after the end of ECC, and one day after the operation respectively. Enzyme-linked immunosorbent assay techniques were used to measure each of the cytokines. RESULTS: Before ECC, there were no differences of the levels of IL-6 and IL-8 among groups (P > 0.05). After ECC, the levels of IL-6 and IL-8 increased significantly in all groups (P < 0.05). The levels on day one after the operation were still higher than those before the operation in all groups (except the level of IL-8 in group C), but no statistical significance was observed. (P > 0.05). At 1 hour after the end of ECC, the level of IL-6 in group B was lower than that in group A, and the level of IL-6 in group C was lower than that in group B, but there was no statistically significant difference (P > 0.05); At the end of ECC, the level of IL-8 in group B was lower than that in group A and the level of IL-8 in group C was lower than that in group B, but no significant difference was noted (P > 0.05). It was also observed that the level of IL-8 was lower in group C than group A or B at 1 hour after the end of ECC. CONCLUSION: Although amrinone and aprotinin have antiinflammatory activity, but pump prime only aprotinin or aprotinin combined with amrinone may fall in preventing proinflammatory cytokine release (IL-6, IL-8) completely in patients with prosthetic valve replacement during ECC perioperative period.

Adult↗
PubMed2001

[Level of nerve growth factor protein in cerebellar cortex of rat pups in intrauterine growth retardation model by clamping the uterine vasculature of pregnant rat].

OBJECTIVE: To understand the level of nerve growth factor (NGF) in the brain of rat pups in intrauterine growth retardation (IUGR), explore the mechanism of brain injury. METHODS: Animal models for IUGR pups were established by clamping the uterine vasculature of pregnant rats with 30 minutes in this study. NGF proteins were measured by immunohistochemistry in the cerebellar cortex of rat pups at birth (21 days of gestation), and on the sixth day after birth. RESULTS: 1. The body weight of the 21-day fetuses in IUGR group decreased 16.1% as compared to that in control group (P < 0.0001); 2. The brain weight of the 21-day fetuses in IUGR group decreased to that in control group (P < 0.05) development of their brain retardation during the intrauterine in IUGR fetus period in this model; 3. On the sixth day after birth, there was no statistical difference in body weight between the IUGR and the control groups. But the brain weight difference between these two groups was still there; 4. At birth and on the sixth day after birth, there were statistical differences in NGF proteins in cerebellum between the IUGR and the control groups, which got along with the decrease of their brain weights. CONCLUSION: A successful animal model of IUGR was established by clamping the uterine vasculature of pregnant rats with 30 minutes, and the development of their brain were retarded in IUGR fetus period in this model. Brain retardation in IUGR pups may relate with the decreased level of NGF in brain. This study discovered that quick "catch-up" growth in physical development and slow "catch-up" growth in brain development in IUGR pups.

Animals↗
PubMed2000

Adeno-associated virus vector carrying human minidystrophin genes effectively ameliorates muscular dystrophy in mdx mouse model.

Duchenne muscular dystrophy (DMD) is the most common and lethal genetic muscle disorder, caused by recessive mutations in the dystrophin gene. One of every 3,500 males suffers from DMD, yet no treatment is currently available. Genetic therapeutic approaches, using primarily myoblast transplantation and adenovirus-mediated gene transfer, have met with limited success. Adeno-associated virus (AAV) vectors, although proven superior for muscle gene transfer, are too small (5 kb) to package the 14-kb dystrophin cDNA. Here we have created a series of minidystrophin genes (<4.2 kb) under the control of a muscle-specific promoter that readily package into AAV vectors. When injected into the muscle of mdx mice (a DMD model), two of the minigenes resulted in efficient and stable expression in a majority of the myofibers, restoring the missing dystrophin and dystrophin-associated protein complexes onto the plasma membrane. More importantly, this AAV treatment ameliorated dystrophic pathology in mdx muscle and led to normal myofiber morphology, histology, and cell membrane integrity. Thus, we have defined minimal functional dystrophin units and demonstrated the effectiveness of using AAV to deliver the minigenes in vivo, offering a promising avenue for DMD gene therapy.

Animals↗
PubMed2000

Protection against ischemic injury in primary cultured mouse astrocytes by bis(7)-tacrine, a novel acetylcholinesterase inhibitor [corrected].

The effects of bis(7)-tacrine, a novel acetylcholinesterase inhibitor, on ischemia-induced cell death and apoptosis were investigated in primary cerebral cortical astrocytes of mice. Following a 6 h in vitro ischemic incubation of the cultures, a marked decrease in the percentage of viable cells was observed by lactate dehydrogenase (LDH) release assay. Furthermore, using bisbenzimide staining, we determined that approximately 65% of the cells underwent apoptosis. Treatment with bis(7)-tacrine (1-10 nM) during ischemic incubation effectively inhibited the ischemia-induced apoptosis, as demonstrated by morphological and biochemical tests. Our results demonstrated that bis(7)-tacrine could protect astrocytes against ischemia-induced cell injury, indicating that the drug might be beneficial for the treatment of vascular dementia, in addition to Alzheimer's disease.

Alzheimer Disease↗
PubMed2000

The use of adeno-associated virus to circumvent the maturation-dependent viral transduction of muscle fibers.

Muscle-based gene therapy using adenovirus, retrovirus, and herpes simplex virus has been hindered by viral cytotoxicity, host immune response, and the maturation-dependent viral transduction of muscle fibers. The development of new mutant vectors has greatly reduced the toxicity and the immune rejection problems, but the inability of viral vectors to penetrate and transduce mature myofibers remains an important issue. Research has been focused on the characterization of barriers to viral transduction in mature myofibers to develop strategies to circumvent the maturation-dependent viral transduction of myofibers. Here, we report that adeno-associated virus (AAV) can be used to overcome the maturation-dependent viral transduction of myofibers. We have investigated by which mechanism AAV can penetrate and efficiently transduce mature muscle fibers, and have shown that this viral vector is not blocked by the basal lamina and that AAV transduction of myofibers is independent of myoblast mediation. Although AAV can efficiently transduce mature myofibers, a differential transduction is still observed among the different types of myofibers that correlates with the expression of the heparan sulfate proteoglycan receptors, the muscle maturity, the number of viral particles used, and the time postinjection. The identification of the mechanisms by which AAV transduces mature myofibers will help in the development of strategies to achieve an efficient muscle-based gene therapy for inherited and acquired diseases.

Animals↗
PubMed2000

[Prognostic effect of angina before acute myocardial infarction in elderly patients].

OBJECTIVE: The present study examined whether angina 48 h before acute myocardial infarction provided protection in early and adult patients. To investigate the effect of ischemic preconditioning in senescent heart. METHODS: We retrospectively verified whether antecedent angina within 48 h myocardial infarction exerted a beneficial effect on in-hospital outcomes in adult(< 60 years old, n = 68) and elderly (> or = 60 years old, n = 118) patients. RESULTS: In-hospital congestive heart failure was more frequent in adult patients without than in those with previous angina(16.7% vs 2.6%, P < 0.05), as were cardiogenic shock and death(23.3% vs 5. 3%, P < 0.05) and the combined end points(in-hospital congestive heart failure and shock or death) (40.0% vs 7.9%, P < 0.01). In contrast, the presence or absence of previous angina before acute myocardial infarction in elderly patients seemed to have no obvious influence, the incidence of in-hospital congestive heart failure(17.7% vs 20.0%, P > 0.05), shock and death(23.5% vs 20.3%, P > 0.05) and combined end points(41.2% vs 40.0%, P > 0.05). But the elderly patients with angina showed a significantly smaller infarct size compared with elderly patients without angina, the long-term cardiogenic death was more frequent in elderly patients without than in those with previous angina(18.0% vs 5.9%, P < 0.05). CONCLUSIONS: The presence of angina before acute myocardial infarction seems to confer significant protection against in-hospital outcomes in adults; this effect seems to be present in elderly patients. This study suggests that the protection afforded by angina in adult and elderly patients may involve the occurrence of ischemic preconditioning.

Aged↗
PubMed2000

Characterisation of membrane phospholipids and glycolipids from a halophilic archaebacterium by high-performance liquid chromatography/electrospray mass spectrometry.

Combined high-performance liquid chromatography and electrospray mass spectrometry (LC/ES-MS) has been used for direct characterisation of the polar membrane lipids in total lipid extracts from Halobacterium salinarium, a species of halophilic archaebacterium. The principle phospholipids found were the diphytanyl archaeol phosphatidylglycerol and diphytanyl archaeol phosphatidylglycerolphosphate methyl ester. The application of LC/ES-MS revealed the additional presence of diphytanyl archaeol phosphatidylglycerol sulphate The extracts also contained an archaeol glycolipid, initially detected in preliminary offline ES-MS studies, which was further characterised by LC/ES-MS and by product ion tandem mass spectrometry (MS/MS) as a sulphate ester of diglycosyl-2,3-di-O-phytanyl-sn-glycerol. Whilst archaeol phospho- and glycolipids containing a (C(20)-C(20))-isopranyl glycerol ether core predominated, LC/ES-MS of the extracts from Halobacterium salinarium indicated the presence of an analogue containing one double bond in its isoprenyl ether core as a minor component of the phosphatidylglycerolphosphate methyl ester fraction, providing a further example of the previously recognised existence of isoprenologues of diphytanyl archaeols which occur as minor components of archaebacterial membrane lipids. The value of these techniques in compositional analysis of archaebacterial lipid extracts is discussed.

Archaea↗
PubMed2000

Quantitative analysis of estrogens in human urine using gas chromatography/negative chemical ionisation mass spectrometry.

A sensitive procedure for the determination of estrogens in urine has been developed, using enzymatic hydrolysis and ether extraction followed by capillary gas chromatography with negative chemical ionisation mass spectrometry (GC/NCI-MS) of the pentafluorobenzoyl derivatives. These derivatives were superior for GC/NCI-MS to trifluoroacetyl, heptafluorobutyl, pentadecafluorooctanoyl and perfluorotolyl derivatives, giving characteristic negative molecular ions as the base peak for each of the naturally occurring estrogens estrone, estradiol and estriol, and for the synthetic estrogen ethynylestradiol used in contraceptive pills. The method was also suitable for determination of some metabolites of estrone and estradiol. The specificity and sensitivity of the GC/NCI-MS method simplifies sample preparation. Recovery of spiked samples was in the range 84-101% for the natural estrogens based on additions to increase the concentration by 5 and 1 microg L(-1). The repeatability of the method was 1-8% for all estrogens.

Benzoates↗
PubMed2000

Therapy and prevention of arthritis by recombinant adeno-associated virus vector with delivery of interleukin-1 receptor antagonist.

OBJECTIVE: To evaluate the recombinant adeno-associated virus vector encoding interleukin-1 receptor antagonist (rAAV-IL-1Ra) complementary DNA for its potential in the treatment and prevention of lipopolysaccharide (LPS)-induced arthritis. METHODS: The therapeutic effect of rAAV-IL-1Ra on arthritis was studied by injecting knees of Sprague-Dawley rats with LPS and rAAV-IL-1Ra and then evaluating the severity of arthritis by leukocyte counts in synovial fluid, histologic changes of synovium, and uptake of 67Ga citrate in joint tissue. To study the therapeutic effect on recurrent arthritis, we induced recurrent arthritis by a second injection of LPS 80 days after primary LPS and rAAV-IL-1Ra injections and then evaluated the severity of recurrent arthritis. To study the prevention of arthritis, rAAV-IL-1Ra was injected into normal joints. After 100 days, LPS was used to induce arthritis, and the severity of arthritis was evaluated. RESULTS: The production of the rAAV-IL-1Ra transgene was up-regulated by LPS-induced joint inflammation and proved to be efficacious in the therapeutic and preventative protocols. Not only primary but also recurrent arthritis could be suppressed by a single injection of rAAV-IL-1Ra. We found that the transgene expression of IL-1Ra could be reactivated by a second challenge with LPS delayed for 80 days after rAAV administration. The therapeutic level of IL-1Ra protein reached a mean +/- SD of 5.8+/-0.5 ng/ml in synovial fluid. In addition, the rAAV transgene persisted within normal joints for at least 100 days and could still be induced to express, after LPS insult, a high level of IL-1Ra (mean +/- SD 5.2+/-0.8 ng/ml) that prevented the occurrence of arthritis. CONCLUSION: This gene therapy, by combining highly efficient and stable rAAV gene delivery, disease-regulated gene expression, and the antiinflammatory effect of IL-1Ra, provides a valuable approach for long-term protection against, and prevention of, arthritis.

Animals↗
PubMed2000

Inefficient formation of a complex among CXCR4, CD4 and gp120 in U937 clones resistant to X4 gp120-gp41-mediated fusion.

Certain subclones (designated as minus clones) of the promonocytic U937 cell line do not support efficient infection and fusion mediated by T cell line adapted (TCLA) X4 HIV-1 gp120-gp41 (Env) although the CXCR4 and CD4 concentrations at their surfaces are similar to those at the surfaces of clones susceptible to HIV-1 entry (plus clones) (H. Moriuchi et al., J. Virol. 71, 9664-9671, 1997). To test the hypothesis that inefficient formation of gp120-CD4-CXCR4 complexes could contribute to the mechanism of resistance to Env-mediated fusion in the minus clones, we incubated plus and minus cells with HIV-1 LAI gp120 and coimmunoprecipitated CD4 by using anti-CXCR4 antibodies. The gp120 induced inefficient coimmunoprecipitation of CD4 in the minus clones but not in the plus ones. Overexpression of CD4 resulted in significant restoration of the minus clones' susceptibility to fusion in parallel with an increase in the amount of the gp120-CD4-CXCR4 complexes. These results not only suggest that the resistance to TCLA X4 HIV-1 entry in the U937 minus clones is due to the inability of these cells to efficiently form complexes among CD4, gp120, and CXCR4, but also provide a direct evidence for the correlation between fusion and the cell surface concentration of the complexes among CXCR4, CD4, and gp120. These data and similar recent observations in macrophages suggest that inefficient complex formation among CXCR4, CD4, and gp120 could be a general mechanism of cell resistance to gp120-gp41-mediated fusion and a major determinant of HIV-1 evolution in vivo.

CD4 Antigens↗
PubMed2000

Interactions of CCR5 and CXCR4 with CD4 and gp120 in human blood monocyte-derived dendritic cells.

Dendritic cells (DC) and macrophages play an important role in the generation of immune responses and transmission of HIV infection. It has been recently found that, in the presence of gp120, CD4 can be efficiently coimmunoprecipitated by anti-CXCR4 antibodies from lymphocytes and monocytes but not from blood monocyte-derived macrophages. The gp120-CD4-CXCR4 complex formation paralleled the ability for these cell types to support X4 (LAV) HIV-1 envelope glycoprotein (Env)-mediated fusion. Here we report that, unlike macrophages but similar to lymphocytes and monocytes, human blood monocyte-derived DC allow efficient complex formation among the HIV-1 coreceptor CXCR4, the primary receptor CD4, and the Env gp120 (LAV) which parallels their fusion ability with cells expressing HIV-1 Env (LAV). In addition, DC behaved similarly to macrophages, lymphocytes, and monocytes in their ability to support formation of complexes between CD4 and the other major HIV-1 coreceptor CCR5 even in the absence of gp120 as demonstrated by CD4 coimmunoprecipitation with anti-CCR5 antibodies. Further, the amount of gp120-CD4-CXCR4 (or CCR5) complexes was proportional to the extent of cell fusion mediated by the HIV-1 Env (LAV or JRFL, respectively). These results demonstrate that of all the major types of host cells important for HIV-1 infection, the first central stage in the entry mechanism, the formation of gp120-CD4-coreceptor complexes, is not impaired except for the formation of the gp120-CD4-CXCR4 complex in macrophages. Therefore, for most CD4+ target cells restraint(s) on productive HIV-1 infection appears to occur at stages of the virus life cycle subsequent to the gp120-CD4-coreceptor complex formation.

Animals↗
PubMed2000

Glycosphingolipids promote entry of a broad range of human immunodeficiency virus type 1 isolates into cell lines expressing CD4, CXCR4, and/or CCR5.

Treatment of human osteosarcoma cells, expressing CD4 and various chemokine receptors, with the glucosylceramide synthase inhibitor 1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol (PPMP), blocked target membrane glycosphingolipid (GSL) biosynthesis and reduced the susceptibility of cells to infection and fusion mediated by envelope glycoproteins from a variety of human immunodeficiency virus type 1 (HIV-1) isolates that utilize CXCR4 and/or CCR5. PPMP treatment of the cell lines did not significantly change the cell surface expression of CD4, CXCR4, and/or CCR5, nor did it alter the chemokine receptor association with CD4. PPMP-treated cells exhibited no changes in chemokine-induced Ca(2+) mobilization and chemotaxis. However, massive envelope glycoprotein conformational changes triggered by CD4 and the appropriate chemokine receptor on the target membrane were inhibited when the target cells were treated with PPMP. Addition of various purified GSLs to PPMP-treated target cells showed that for all isolates tested, globotriaosylceramide (Gb3) was the most potent GSL in restoring the fusion susceptibility of target cells with cells expressing HIV-1 envelope glycoproteins; addition of the monosialoganglioside GM3 yielded a slight enhancement of fusion susceptibility. Our data are consistent with the notion that a limited number of specific GSL species serve as crucial elements in organizing gp120-gp41, CD4, and an appropriate chemokine receptor into a membrane fusion complex.

3T3 Cells↗
PubMed2000

Full functional rescue of a complete muscle (TA) in dystrophic hamsters by adeno-associated virus vector-directed gene therapy.

Limb girdle muscular dystrophy (LGMD) 2F is caused by mutations in the delta-sarcoglycan (SG) gene. Previously, we have shown successful application of a recombinant adeno-associated virus (AAV) vector for genetic and biochemical rescue in the Bio14.6 hamster, a homologous animal model for LGMD 2F (J. Li et al., Gene Ther. 6:74-82, 1999). In this report, we show efficient and long-term delta-SG expression accompanied by nearly complete recovery of physiological function deficits after a single-dose AAV vector injection into the tibialis anterior muscle of the dystrophic hamsters. AAV vector treatment led to more than 97% recovery in muscle strength for both the specific twitch force and the specific tetanic force, when compared to the age-matched control. Vector treatment also prevented pathological muscle hypertrophy and resulted in normal muscle weight and size. Finally, vector-treated muscle showed substantial improvement of the histopathology. This is the first report of successful functional rescue of an entire muscle after AAV-mediated gene delivery. This report also demonstrates the feasibility of in vivo gene therapy for LGMD patients by using AAV vectors.

Animals↗
PubMed2000

Recombinant adeno-associated virus expressing human papillomavirus type 16 E7 peptide DNA fused with heat shock protein DNA as a potential vaccine for cervical cancer.

In this study, we explore a potential vaccine for human papillomavirus (HPV)-induced tumors, using heat shock protein as an adjuvant, a peptide vaccine for safety, and adeno-associated virus (AAV) as a gene delivery vector. The tumor vaccine was devised by constructing a chimeric gene which contained HPV type 16 E7 cytotoxic T-lymphocyte (CTL) epitope DNA (M. C. Feltkamp, H. L. Smits, M. P. Vierboom, R. P. Minnaar, B. M. de Jongh, J. W. Drijfhout, J. ter Schegget, C. J. Melief, and W. M. Kast, Eur. J. Immunol. 23:2242-2249, 1993) fused with the heat shock protein gene as a tumor vaccine delivered via AAV. Our results demonstrate that this vaccine can eliminate tumor cells in syngeneic animals and induce CD4- and CD8-dependent CTL activity in vitro. Moreover, studies with knockout mice with distinct T-cell deficiencies confirm that CTL-induced tumor protection is CD4 and CD8 dependent. Taken together, the evidence indicates that this chimeric gene delivered by AAV has potential as a cervical cancer vaccine.

Animals↗
PubMed2000

Development of an affordable diaphragmatic pump for cardiopulmonary bypass: an in vivo evaluation.

A new diaphragmatic pump (L-Y pump) and its drive unit were developed in our institute. The pump has a priming volume of 80 ml. The pump housing is 72 mm in diameter and 42 mm in height. Its total weight is 139 g. To assess and confirm the function and controllability of this pump, comparative studies of cardiopulmonary bypass (CPB) with L-Y pump (group A) and conventional roller pump (Group B) were performed using dogs. Both pumps provided pump flow of 90 to 100 ml/kg/min. The hemodynamics of both groups were stable and within the normal range. No leakage or thrombus formation was observed in the L-Y pump. All biochemistry data showed no significant differences between the 2 groups. This data demonstrated low plasma-free hemoglobin levels in the L-Y pump group; after 120 min of CPB, mean plasma free hemoglobin levels were 48.7 +/- 8.6 mg/dl in the roller pump group and 21.4 +/- 7.1 mg/dl in the L-Y pump group, and minimal hemolysis was indicated. In conclusion, this L-Y pump and its controller system might be useful for CPB in terms of its low hemolysis and good pump quality. This pump demonstrated easy manipulation, good controllability, and provided a sufficient pulsatile flow. This pump is suitable not only for CPB, but also as a long-term circulatory support system.

Animals↗