Search PubMed⌕ Search

Biomedical subjects

X Xiao

Publications and source records attributed to X Xiao.

At least 109 records · Page 6Linked to original sources
PubMed1999

rAAV vector-mediated sarcogylcan gene transfer in a hamster model for limb girdle muscular dystrophy.

The limb girdle muscular dystrophies (LGMD) are a genetically and phenotypically heterogeneous group of degenerative neuromuscular diseases. A subset of the genetically recessive forms of LGMD are caused by mutations in the four muscle sarcoglycan genes (alpha, beta, gamma and delta). The coding sequences of all known sarcoglycan genes are smaller than 2 kb, and thus can be readily packaged in recombinant adeno-associated virus (rAAV) vectors. Previously, we have demonstrated highly efficient and sustained transduction in mature muscle tissue of immunocompetent animals with rAAV vectors. In this report, we utilize recombinant AAV containing the delta-sarcoglycan gene for genetic complementation of muscle diseases using a delta-sarcoglycan-deficient hamster model (Bio 14.6). We show efficient delivery and widespread expression of delta-sarcoglycan after a single intramuscular injection. Importantly, rAAV vector containing the human delta-sarcoglycan cDNA restored secondary biochemical deficiencies, with correct localization of other sarcoglycan proteins to the muscle fiber membrane. Interestingly, restoration of alpha-, as well as beta-sarcoglycan was homogeneous and properly localized throughout transduced muscle, and appeared unaffected by dramatic overexpression of delta-sarcoglycan in the cytoplasm of some myofibers. These results support the feasibility of rAAV vector's application to treat LGMD by means of direct in vivo gene transfer.

Animals↗
PubMed1999

Telomere dynamics in monkeys: increased cell turnover in macaques infected with chimeric simian-human immunodeficiency viruses.

To address the question of how cell turnover is affected by retroviral infections, we used the telomeric terminal restriction fragments (TRFs) as markers of cell replicative history and measured their length in macaques infected with chimeric simian-human immunodeficiency viruses (SHIVs). The TRF lengths of mononuclear cells in 104 samples, including longitudinal samples from nine cynomolgus and ten pig-tailed macaques infected with SHIV, and in samples from 26 uninfected macaques, were quantitated by an improved method, based on two-dimensional calibration of DNA sizes, pulsed field electrophoresis, and high-resolution Southern blot images. The average TRF lengths of peripheral blood mononuclear cells (PBMCs) from uninfected pig-tailed (14.9+/-1.6 kbp) and cynomolgus (14.1+/-1.8 kbp) macaques were about 3 and 5 kbp longer than those of human infants and 30-year-old adults, respectively. The rate of TRF length shortening in infected pig-tailed macaques was significantly (P = 0.035) higher (2.2-fold) than in uninfected monkeys. The TRFs in SHIV-infected cynomolgus monkeys, which, in general, had lower viral loads than pig-tailed macaques, shortened on average more rapidly (1.6-fold) than in uninfected animals, but the difference was not statistically significant. The TRFs of mononuclear cells from the lymph nodes of two rapidly progressing SHIV-infected macaques that developed AIDS and died also shortened in parallel but somewhat more rapidly than in the PBMCs. These results suggest that the rate of PBMC turnover in macaques could be increased several-fold during infections by immunodeficiency viruses, likely due to immune activation by SHIV antigens.

Animals↗
PubMed1999

Disease-inducible transgene expression from a recombinant adeno-associated virus vector in a rat arthritis model.

Rheumatoid arthritis (RA) is a systemic autoimmune disease affecting 1% of the world's population, with significant morbidity and mortality. In this study, we investigated a recombinant adeno-associated virus (rAAV) vector for its potential application in RA gene therapy. rAAV encoding Escherichia coli beta-galactosidase was injected into rat joints which had already been induced into acute arthritis after local lipopolysaccharide (LPS) administration, and the efficiency of in vivo transduction was evaluated. We observed a striking correlation between vector transgene expression and disease severity in arthritic joints. The inflammatory reaction peaked at 3 to 7 days after LPS treatment, and, at the same time, 95% of the synoviocytes had high-level transgene expression. Gene expression diminished to the basal level (5%) when the inflammation subsided at 30 days after LPS treatment. More importantly, the diminished transgene expression could be efficiently reactivated by a repeated insult. The transgene expression in normal joints transduced with rAAV remained low for a long period of time (30 days) but could still be induced to high levels (95%) at 3 to 7 days after LPS treatment. This is the first demonstration of disease state-regulated transgene expression. These findings strongly support the feasibility of therapeutic as well as preventative gene transfer approaches for RA with rAAV vectors containing therapeutic genes, which are expected to respond primarily to the disease state of the target tissue.

Animals↗
PubMed1999

[Analysis of fusion points in hybrid genes and gene deletion for congenital red-green color vision defects].

OBJECTIVE: To investigate gene deletion and the fusion points of hybrid genes in congenital red-green color vision defects. METHODS: Genomic DNA was collected from 11 protans, 19 deutans and 5 normal controls. Promoter and exons 2-5 of the red and green pigment genes in these subjects were analyzed by using PCR-Heteroduplex-SSCP analysis. The origin and component of each individual gene were determined by comparison with the patterns of known sequence of the red and green visual pigment genes. RESULTS: Fourteen out of the 30 patients with red-green color vision defects were found to have hybrid gene. The fusion points of the hybrid gene were located in exon 1-intron 1(4 cases), introns 2-3(5 cases) and intron 4 (5 cases). CONCLUSION: The fusion point of a hybrid gene may occur in exon 1-intron 1 and intron 4 as well as in introns 2-3(including exon 3).

Artificial Gene Fusion↗
PubMed1999

[Determination on chemical constituents of Curcuma L. produced in China].

OBJECTIVE: To provide some valuable information for the research on species systematization and quality standardization of Curcuma drugs. METHODS: Colorimetry, TLC-colorimetry and water vapour distillation were used to determine the contents of curcuminoids, curcumin and essential oils of 34 samples of Curcuma produced in China. RESULTS AND CONCLUSION: The contents of curcuminoids and curcumin are different upto an extent of over 100 times among the varieties of Curcuma, and those of essential oils to an extent of 6 times. But there is little difference in the samples of the same species from different producing areas. There is also an obvious correlativity between the contents of curcuminoids and essential oils in the varieties of curcuma.

Curcuma↗
PubMed1999

[Anaerobic bacterial analysis of 436 specimens of clinical infection].

This study was aimed at the relationship between anaerobes and clinical infection. Aerobic and anaerobic bacterial culture was performed for 436 specimens of clinical infection. The incidence of anaerobic bacteria isolates and predominant species were analyzed. The results showed that the incidence of anaerobic isolates was 88.3% (385/436), the main predeminoue species were Gram negative nonsporeforming anaerobic rods (Bacteroids, Prevotella and Porphyromonas) and peptostreptococcus. The endogenous infection, caused by anaerobic microflora of human body as the main pathogens, and the mixed bacterial infection are the most common feature of human clinical anaerobic infections.

Adolescent↗
PubMed1999

[Leukocyte adhesion molecule expression and circulating ICAM-1, E-selectin levels during cardiopulmonary bypass in patients undergoing valve replacement].

The objectives of this study were to measure leukocyte adhesion molecule expression, assess the possibility of evaluating the serum levels of the soluble form of endothelium adhesion molecule as an alternative for endothelia cell activation, and analyze the correlation and regression between leukocyte adhesion molecule expression and soluble endothelium adhesion molecule levels during cardiopulmonary bypass (CPB) in patients undergoing valve replacement. Twelve adult patients were included in this study. The extracorporeal circuit was primed with Ringer's lactate. After systemic heparinization (300 IU/kg), CPB was initiated with a bubble oxygenator. Patients were cooled to about 28 degrees C, at that temperature, aorta was clamped and cold crystalloid cardioplegia was delivered into aortic root. The activatal clotting time was maintained at greater than 450 seconds. 1-1. 3 mg of protamine was administered for each 100 IU of heparin given prior to CPB. Peripheral blood was collected at the day prior to surgery and the morning of postoperative days 1, 2, 5, and 7 for determination of the expression of leukocyte CD11a, CD18, CD11a/CD18, CD11b, CD11b/CD18 (immunofluorescent flow cytometry) and the plasma soluble intercellular adhesion molecule-1(sICAM-1), soluble E-selectin (sE-selectin) (enzyme-linked immunoabsorbent assay). CPB caused a sustained increase in the leukocyte CD11a, CD18, CD11a/CD18, CD11b/CD18 expression and the plasma sICAM-1, sE-selectin levels in patients (P < 0.05). Upregulation of the leukocyte adhesion molecule expression and increase of the circulation endothelium adhesion molecule levels lasted at least 2 days after surgery (P < 0.05) except CD11a. There were correlation and regression between leukocyte adhesion molecule expression and soluble endothelium adhesion molecule levels (r = 0.91-0.99, P = 0.0322-0.0005; Y = -1377.06-44.64 + 1.49-14.78a to Y = 44.64 + 1.49a). These results suggest that CPB causes obvious leukocyte-endothelia interactions, that the expression of these adhesion molecules are presented by means of receptor-ligand form, and that the measurement of sICAM-1 and sE-selectin may well be used as a marker of endothelial cell activation.

Adult↗
PubMed1999

[A probe in good agricultural practice for traditional Chinese drugs].

OBJECTIVE: To provide some scientific reference for the good agricultural practice (GAP) for traditional Chinese drugs (TCDs). METHOD: Based on an integrated analysis of the factors bearing on the output and quality of TCD along with a study on the possible pollution sources of TCDs, some initial idea concerning the research and scope of GAP has been outlined. RESULT AND CONCLUSION: GAP for TCDs should be designed to incorporate large-scale production bases, standardization of drug varieties, optimization of planting techniques, rationalization of harvesting and processing, establishment of famous brands for quality TCDs, pollution-free production and circulation, efficient coordination of production, supply and marketing, etc.

Drugs, Chinese Herbal↗
PubMed1999

[Effects of warm blood and clot crystalloid cardioplegia on the heart rate variability of canine].

The objectives of this study were to explore the mechanisms of cardiac autonomic system (CAS) impairment and to assess whether warm blood cardioplegia can prevent the decrease of heart rate variability (HRV) after CPB. Twelve adult mongrel dogs were divided into two groups. One group received warm blood cardioplegia and maintained at a systemic temperature of 38 degrees C throughout the experiment (WB group). The other received cold crystalloid cardioplegia at 31 degrees C and topical hypothermia (CC group). Anesthesia was induced and maintained with sodium pentobarbital and isoflurane. The heart was exposed through a right thorectomy. CPB was established using a single right atrial cannula. The arterial cannula was placed in the right femoral artery. The crossclamp time for both groups was 30 minutes. Serum potassium levels were normalized throughout the study. Each animal's ECG was continuously recorded for 24 hours before surgery and for the first five postoperative days (POD) using a two-channel Holter monitor. The data were analyzed for heart rate variability (TP = total power, 0.01-1.00; LF = low frequency, 0.04-0.15; HF = high frequency, 0.15-0.40; LF/HF). There were no differences in the preoperative values. In both groups the TP, LF, and HF decreased, compared to control (P < 0.05), with CC group having significantly lower TP, LF and HF than the WB group (P < 0.05). The LF/HF did not change both between groups and between before- and after-CPB in each group (P > 0.05). The mean heart rate at 24 hours (MHR) increased in both groups, compared to control (P < 0.05), with CC group having a significantly higher MHR than WB group (P < 0.05). The data suggest that CPB, with warm blood or cold crystalloid cardioplegia does not disturb the balance of CAS, but it causes the decrease of HRV, and warm blood cardioplegia can not prevent the impairment of HRV.

Animals↗
PubMed1999

[Left ventricular function evaluation after mitral valve replacement with preservation the subvalvular apparatus].

The objective of this study was to evaluate the left ventricular function after mitral valve replacement (MVR) with preservation of all chordae. Fourteen patients with a diagnosis of mitral regurgitation were studied. These patients, 4 males and 10 females, age from 24 to 59 years, who underwent mitral valve replacement, in which all chordae tendineae were preserved. The mean follow-up interval was 6 months. Preoperation and postoperation multigated equilibrium radionuclide angiography was performed by Elscint Helix Apex SPECT. Each patient was injected with 740MBq 99mTc-HSA, rest ejection fraction (global EF) of LV (%), regional ejection fraction (EF) of LV (%), PER/S and PFR/S were measured. Regional EF was calculated by the method of dividing the left ventricle into five segments by radial axis. The results showed that the postoperative EF of the whole left ventricle of the chordae-preserved patients was significantly greater than their preoperative EF (40.0% +/- 17.8%, to 51.6% +/- 18.2%, P < 0.02), and also the regional EF at the lateral wall of the chordae-preserved MVR was significantly greater than the preoperative regional EF (an increase from 51.0% +/- 18.1% to 69.7% +/- 21.2%, P < 0.01). MVR with preservation of all chordae, the patient's left ventricular function remarkably improved.

Adult↗
PubMed1999

[Genotype-phenotype correlation in Chinese patients with retinitis pigmentosa due to rhodopsin mutation].

PURPOSE: To investigate the genotype-phenotype correlation in Chinese patients with retinitis pigmentosa caused by rhodopsin gene mutation. METHODS: On the basis of the onset of symptoms, degree of morphological changes and progression of visual disability in three (3/83) patients with identified mutations, the correlation of the phenotype with the corresponding mutations was assessed. RESULTS: There was a certain degree of allele-specificity. Severe form of retinitis pigmentosa was found in patients with mutation in the cytoplasmic domain and mild form of retinitis pigmentosa in patients with mutation in the intradiscal domain. CONCLUSION: Although there is a certain relation between the mutant rhodopsin and ocular manifestation, we need to accumulate more materials before relating a rhodopsin mutation to a specific phenotype.

Adult↗
PubMed1999

Differential gene expression in retina of myopic chicken eyes using mRNA differential display.

PURPOSE: To study differentially expressed genes in retina of experimental myopic chicken. METHODS: Experimental myopia in chicken was induced by form-deprivation. The mRNA in chicken retina was analyzed by using differential display. RESULTS: Experimental myopia was successfully induced in chicken through form-deprivation. Differentially expressed gene fragments were detected in retina of chicken with myopic development and recovery as compared with normal controls. CONCLUSION: The differential display of mRNA may be a useful way in cloning myopic-related genes.

Animals↗
PubMed1998

[Heat strain for personnel wearing three levels of protective ensembles at moderate and heavy workloads].

The effects of individual protective ensembles and workloads on personnel's physiological heat strain were experienced by personnel in a hot environment (35 degrees C, 55% relative humidity). Six young males performed treadmill tests at both moderate (ML: 1.11 m/s, 5% grade) and heavy (HL: 1.34 m/s, 5% grade) workloads. They wore three levels of protective ensembles: protective mask only (PM), protective clothing only (PC), and full protective ensembles (FP). Tests lasted 60 min and 45 min, respectively, for ML and HL. Physiological measurements included heart rate (HR), rectal (Tre) and skin (Tsk) temperature, sweat rate (SR), and sweat evaporative rate (ER). Differences between the ensembles and the workloads were significant for HR responses. The increase rate in Tre and Tsk, and SR, ER were significantly reduced from PM and PC to FP condition during ML and Hl tests. The sweat evaporation restriction of ensembles and the increase of heat production from exercise are the main factors of enhancing the heat strain.

Adult↗
PubMed1998

HIV coreceptors.

Explore the source record for details and available documents.

3T3 Cells↗
PubMed1998

VLA-5 is expressed by mouse and human long-term repopulating hematopoietic cells and mediates adhesion to extracellular matrix protein fibronectin.

Fibronectin (FN), an extracellular matrix protein, is involved in the adhesion and migration of hematopoietic cells and has been shown to enhance retroviral gene transfer into primitive hematopoietic cells by co-localization of target cells and retrovirus when used as a substrate in vitro. We have previously found that mouse hematopoietic stem cells could be transduced on a FN fragment that included the recognition sequence Arg-Gly-Asp (RGD), suggesting that stem cells may express the integrin very late antigen (VLA)-5. To address this, we investigated the binding of mouse and human hematopoietic cells to recombinant peptides that contained one or a combination of the three principle cell-binding domains of FN. These domains included the VLA-5- binding sequence RGD, the VLA-4-binding site CS1, and the high affinity heparin-binding domain. Here we show that mouse long-term in vivo repopulating stem cells, as well as primitive human NOD/SCID mouse repopulating cells, can bind extracellular matrix protein FN by using integrin VLA-5 in vitro. This binding is specific and can be inhibited by antibodies to VLA-5. In addition, preincubation of BM cells with peptide CH-296, which contains all three primary FN-binding domains, decreased the engraftment of cells in the bone marrow in vivo, while intravenous injection of the same peptide induced an increase of progenitor cells in the spleen. In summary, our data demonstrate that VLA-5 is expressed on primitive mouse and human hematopoietic cells and suggest that there may be significant cooperation between integrin receptors and proteoglycan molecules in the engraftment of bone marrow cells and hematopoietic cell adhesion in vivo.

Animals↗
PubMed1998

Targeted disruption of heat shock transcription factor 1 abolishes thermotolerance and protection against heat-inducible apoptosis.

Heat shock transcription factor 1 (HSF1) is a member of the vertebrate HSF family that regulates stress-inducible synthesis of heat shock proteins (HSPs). Although the synthesis of the constitutively expressed and inducible members of the heat shock family of stress proteins correlates with increased cellular protection, their relative contributions in acquired cellular resistance or "thermotolerance" in mammalian cells is presently unknown. We report here that constitutive expression of multiple HSPs in cultured embryonic cells was unaffected by disruption of the murine HSF1 gene. In contrast, thermotolerance was not attainable in hsf1(-/-) cells, and this response was required for protection against heat-induced apoptosis. We conclude that 1) constitutive and inducibly expressed HSPs exhibit distinct physiological functions for cellular maintenance and adaptation, respectively, and 2) other mammalian HSFs or distinct evolutionarily conserved stress response pathways do not compensate for HSF1 in the physiological response to heat shock.

Alleles↗