Biomedical subjects

X Xia

Publications and source records attributed to X Xia.

At least 55 records · Page 3Linked to original sources

PubMed2001

A study of factors related to the incidence of cataract in patients with non-insulin dependent diabetes mellitus.

PURPOSE: To investigate the factors related to the development of cataract in patients with non-insulin dependent diabetes mellitus(NIDDM). METHODS: 792 NIDDM patients received ophthalmologic examinations including visual acuity, external status of the eyes, slit lamp microscopy and ophthalmoscopy. Glucose, urea nitrogen(BUN), creatinine(Cr), urine acid(UA), N-acetyl-beta 2-D-glucosaminidase (NAG), beta 2-microglobulin(beta 2-MG) and serum albumin in blood were quantitatively tested. Glucose, pH value, protein, cells, cast and ketobodies in urine were assayed. Diagnosis of cataract was based on lens opacities classification system II. Any patient meeting "NII", "CII" or "PII" level was diagnosed as cataract. RESULTS: The incidence of cataract in this group of NIDDM was 62.37% (494/792), which significantly related to the duration of the disease course, but not to the sex of the patient. The occurrence rate of cataract in patients suffering from NIDDM of less than five years duration, from five to ten years, and more than ten years was 49.67% (228/459), 71.84% (125/174), and 88.68% (141/159), respectively. The occurrence of cataract in patients diagnosed of the disease from five to ten years and more than ten years was much higher than that of those with the course of the disease less than five years(P < 0.05 and P < 0.001, respectively). Rising concentrations of blood urea nitrogen, creatinine, glycosylated hemoglobin HbA1c(G-HbA1c), N-acetyl-beta 2-D-glucosaminidase(NAG) and beta 2-microglobulin(beta 2-MG) indicated malfunction of the kidneys, and the rate of cataract occurrence in these patients was higher. CONCLUSION: This study indicates that prolongation of the duration of non-insulin dependent diabetes mellitus, renal dysfunction, as well as poor blood glucose control, may accelerate the development of cataract.

Acetylglucosaminidase↗

PubMed2001

[Clinical observation on effect of baisuifang oral liquid in treating vascular dementia].

OBJECTIVE: To study the effect of Baisuifang Oral Liquid (BSF) in treating vascular dementia. METHODS: Patients selected according to the diagnostic standard of American Association of Psychiatry were randomly divided into two groups, the 37 patients in the BSF treated group and the 28 patients in the control group treated by Naofukang with therapeutic course of 3 months. Changes of clinical symptoms, TCM Syndrome, mini-mental state examination (MMSE) and activity of daily living (ADL) score, hemorrheologic characters, platelet aggregation and blood lipid were observed. RESULTS: BSF could ameliorate the symptoms and TCM Syndrome, decrease blood lipid, improve the hemorrheologic character, elevate the MMSE and ADL score of patients. The total effective rate in the treated group was 75.68% and the markedly effective rate 24.32%, which were obviously superior to those in the control group respectively. CONCLUSION: BSF is an effective Chinese herbal preparation in treating vascular dementia, which could promote the restoration of learning memory, and improve the clinical symptoms.

Administration, Oral↗

PubMed2000

H(2)O(2)-induced egr-1, fra-1, and c-jun gene expression is mediated by tyrosine kinase in aortic smooth muscle cells.

Hydrogen peroxide (H(2)O(2)) has recently been shown to have a dual effect on cell growth by stimulating proliferation and triggering apoptosis. Apoptosis induced by H(2)O(2) is a direct consequence of oxidant injury, while the proliferative response to H(2)O(2) is thought to be a protective mechanism against oxidant injury. Signaling of the H(2)O(2)-induced proliferative effect has been proposed to occur via the activation of mitogen-activated protein kinase (MAPK) and increase in expression of transcription factors. In the present study, H(2)O(2)-induced mitogenic signaling in aortic smooth muscle cells (ASMC) was investigated with a specific focus on the roles of tyrosine kinase and tyrosine phosphatase in the regulation of the H(2)O(2)-stimulated egr-1, fra-1, and c-jun transcription. The results show that H(2)O(2)-induced increases in egr-1, fra-1, and c-jun mRNA levels, as measured by Northern blot analysis, are time and dose dependent with the peak of the response within 2 h. Tyrosine kinase inhibitors (genistein, amino-genistein, and tyrphostin 51) significantly attenuated H(2)O(2)-induced expression of these genes and a tyrosine phosphatase inhibitor (perox-vanadate) stimulated their expression. H(2)O(2) stimulated tyrosine kinase activities and caused protein tyrosine phosphorylation, which was blocked by tyrphostin 51. H(2)O(2) also caused tyrosine phosphorylation of platelet derived growth factor (PDGF) receptor. These data show that H(2)O(2) increases egr-1, fra-1, and c-jun mRNA levels in vascular smooth muscle cells, and the increase in expression of these genes is mediated by activation of tyrosine kinase. Our data also provide evidence that the H(2)O(2)-induced mitogenic response is, in part, mediated through the receptor tyrosine kinase, PDGF receptor.

Animals↗

PubMed2000

Fragilities of liquids predicted from the random first order transition theory of glasses.

A microscopically motivated theory of glassy dynamics based on an underlying random first order transition is developed to explain the magnitude of free energy barriers for glassy relaxation. A variety of empirical correlations embodied in the concept of liquid "fragility" are shown to be quantitatively explained by such a model. The near universality of a Lindemann ratio characterizing the maximal amplitude of thermal vibrations within an amorphous minimum explains the variation of fragility with a liquid's configurational heat capacity density. Furthermore, the numerical prefactor of this correlation is well approximated by the microscopic calculation. The size of heterogeneous reconfiguring regions in a viscous liquid is inferred and the correlation of nonexponentiality of relaxation with fragility is qualitatively explained. Thus the wide variety of kinetic behavior in liquids of quite disparate chemical nature reflects quantitative rather than qualitative differences in their energy landscapes.

Journal Article↗

PubMed2000

A recombinant antibody-targeted plasminogen activator with high affinity for activated platelets increases thrombolytic potency in vitro and in vivo.

To increase thrombolytic specificity of urokinase (uPA), we engineered a recombinant chimeric plasminogen activator SZ51Hu-scuPA, which consists of a humanized monoclonal antibody (SZ-51Hu) specifically against P-selectin on activated human platelet and a single-chain urokinase (scuPA). The cDNA, encoding scuPA amino acids 1-411, was inserted in 5' end to 3' end orientation immediately after the CH3 of SZ-51Hu heavy-chain sequence in the expression vector alphaLys30. The resulting construct alphaLys30-SZ51VH/Hu-scuPA was used to transfect into SP2/0 murine myeloma cell line, which was pretransfected with SZ51Hu light chain. The fusion protein SZ51Hu-scuPA was expressed at 5 mg/L in the supernatant of cell culture. The fusion protein purified by affinity chromatography had a molecular weight of 160 kDa with fibrinolytic activity of 39,000 IU/mg and its affinity to activated human platelet was 67% of the parent murine mAb SZ-51. The thrombolytic property of the fusion protein was first characterized in an in vitro system, which consists of a 125I-fibrin-labeled human plasma clot containing different concentrations of human platelets suspended in citrated human plasma. Fifty percent lysis was reached with SZ51Hu-scuPA in 1 hour at a concentration of 20 IU/mL or in 2 hours at a concentration of 10 IU/ mL, which was much faster than uPA at the same concentration. The maximal lysis of the clots by SZ51Hu-scuPA was 4.1 to 8.4 times more potent than that by uPA. The fusion protein was further characterized in the hamster pulmonary embolism model with clots prepared from fresh platelet-rich human plasma containing 125I-labeled fibrinogen. The thrombolytic activity of SZ51-scuPA was 3.9 times more potent than that of uPA at 2,000 IU/kg in this model. Almost no significant fibrinogen breakdown was observed either in vitro and in vivo.

Animals↗

PubMed2000

Ectopic expression of the ErbB-3 binding protein ebp1 inhibits growth and induces differentiation of human breast cancer cell lines.

Ebp1, an ErbB-3 binding protein, translocates from the cytoplasm to the nucleus of human breast cancer cells after treatment with the ErbB-3 ligand, heregulin. The purpose of these studies was to examine the effects of ectopic expression of ebp1 on the biological properties of human ErbB-3-expressing breast carcinoma cell lines. Ectopic expression of ebp1 in ErbB-2, ErbB-3-expressing breast carcinoma cell lines resulted in inhibition of colony formation, a decreased proliferation rate, an accumulation of cells in the G2/M phase of the cell cycle, and suppression of growth in soft agar. Ectopic expression of ebp1 led to a more differentiated phenotype in AU565 breast cancer cells, as evidenced by increased expression of lipid droplets and of the milk protein casein. Basal phosphorylation of extracellular regulated kinases (Erks) 1 and 2, kinases activated by heregulin treatment, was also observed in ebp1 transfectants. The promoter for the intercellular adhesion molecule-1 gene, a heregulin-inducible gene, was constitutively activated in ebp1 transfectants as determined by reporter construct analysis. These data demonstrate that ectopic expression of the ErbB-3 binding protein Ebp1 inhibits proliferation and induces differentiation of ErbB-2, ErbB-3-expressing human breast carcinoma cell lines.

Breast Neoplasms↗

PubMed2000

Compensatory head posture changes in patients with obstructive sleep apnea.

The upper airway narrowing and changes in head posture and their relationship with apnea severity in patients with obstructive sleep apnea (OSA) were investigated. In 86 male OSA patients and 37 healthy men, one-night polysomnographic examination was performed and a lateral cephalogram by digital image processing system was taken in each subject. Fifteen variables concerning the upper airway dimensions, area and head postures were measured by using a computer software (NIH Image). The results showed that upper airway dimensions in the OSA group at all levels were significantly smaller than those in the control group and the results hold true when the age and body mass index were well controlled in these two groups. Significant forward inclination of the cervical column was found in the patients with an apnea index (AI) greater than 35 episodes/h. And changes in the head posture variables in the whole study group were significantly correlated with AI and airway dimensions at various levels. It was suggested that there exist significant and extensive upper airway narrowing in OSA patients even in upright position and awake state; And as the apnea severity progresses, patients may assume certain compensatory head postures in an attempt to maintain an adequate airway patency.

Adaptation, Physiological↗

PubMed2000

Phylogenetic relationship among horseshoe crab species: effect of substitution models on phylogenetic analyses.

The horseshoe crabs, known as living fossils, have maintained their morphology almost unchanged for the past 150 million years. The little morphological differentiation among horseshoe crab lineages has resulted in substantial controversy concerning the phylogenetic relationship among the extant species of horseshoe crabs, especially among the three species in the Indo-Pacific region. Previous studies suggest that the three species constitute a phylogenetically unresolvable trichotomy, the result of a cladogenetic process leading to the formation of all three Indo-Pacific species in a short geological time. Data from two mitochondrial genes (for 16S ribosomal rRNA and cytochrome oxidase subunit I) and one nuclear gene (for coagulogen) in the four species of horseshoe crabs and outgroup species were used in a phylogenetic analysis with various substitution models. All three genes yield the same tree topology, with Tachypleus-gigas and Carcinoscorpius-rotundicauda grouped together as a monophyletic taxon. This topology is significantly better than all the alternatives when evaluated with the RELL (resampling estimated log-likelihood) method.

Animals↗

PubMed2000

[In vitro study on transduction of human O(6)-methylguanine-DNA-methyltransferase cDNA into human umbilical cord blood CD34(+) cells].

OBJECTIVE: To explore human umbilical cord blood hematopoietic progenitor cells transduced with human O(6)-methylguanine-DNA-methyltransferase (MGMT) gene increase resistance to 1,3-Bis(2-Chloroethyl)-1-Nitrosourea(BCNU). METHODS: The present authors obtained a full length cDNA fragment encoding the human MGMT from a patient with cholelithiasis liver tissue by RT-PCR method and confirmed by DNA sequencing. The fragment was cloned into pGEM-T vector and further subcloned into G1Na retrovirus vector. Then the G1Na-MGMT was transfected into the packaging cell lines GP+E86 and PA317 by LipofectAMINE method; using the medium containing BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, the authors obtained high titer amphotropic PA317 producer clone with the highest titer up to 1.6x10(6) CFU/ml. Cord blood CD34(+) cell were transfected repeatedly with supernatant of retrovirus containing human MGMT cDNA under stimulation of hemopoietic growth factors. RESULTS: PCR, RT-PCR, Southern blot, Northern blot, Western blot and MTT analyses showed that MGMT gene had been integrated into the genomic DNA of cord blood CD34(+) cells and expressed efficiently in the transfected cells. The transgene recipient cells conferred 4 folds stronger resistance to BCNU than that of the non-transduced. CONCLUSION: The retrovirus vector-mediated transfer of MGMT drug resistance gene into human cord blood CD34(+) cells and expression could confer the resistance of transgene cells to BCNU toxicity.

Antigens, CD34↗

PubMed2000

[Comparative study of clinical features of childhood and adult acute lymphoblastic leukemia].

OBJECTIVE: To analyze the outcome, the immunological and cytogenetic characteristics and the frequency of primary multi-drug resistance of childhood acute lymphoblastic leukemia (ALL) in our hospital during the past two years. METHOD: The complete remission (CR) rate of 154 newly diagnosed ALL patients were analysed and the biological features of the leukemic cells were explored by immunochemistry and cytogenetics. RESULTS: The CR rate in the ALL children is 94.1% which is significantly higher than that of adult ALL patients (67.8%). Immunophenotype analysis showed that 18.5% of the children expressed myeloid antigens besides lymphoid antigens and 4.8% of them were Ph chromosome positive. Both the figures were lower than that of adult patients. CONCLUSION: Childhood ALL has distinct morphological, immunological and cytogenetic (MIC) features, which might contribute to the good prognosis of the patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

[Analysis of surface markers of expanded human umbilical cord blood cells in vitro].

OBJECTIVE: To explore the optimal timing for in vitro expansion and transplantation of umbilical cord blood hematopoietic cells. METHODS: Hematopoietic cells from human umbilical cord blood were cultured with G-CSF, GM-CSF, rIL-3, rIL-6, SCF and Epo in a long term culture system, the cell cycle and cellular markers were analysed dynamically. RESULTS: CD(3)(+), CD(4)(+)/CD(45RO)(+) and CD(8)(+)/CD(45RO)(+) cells increased at day 3, and reached the highest level at day 7, decreased at day 14, and remained lower level at day 21. CD(4)(+) and CD(8)(+) cells showed no change at day 7, decreased at day 14, and decreased further at day 21. CD(4)(+)/CD(45RA)(+) and CD(8)(+)/CD(45RA)(+) cells decreased after day 3, and decreased further at day 14. HLA-DR(+) cells increased from day 3 to day 7. CD(34)(+) cells increased at day , reached the highest level at day 7, and decreased at day 14. CD(34)(+), CD(34)(+) CD(38)(-), CD(34)(+) CD(38)(+) cells increased 8.8, 7.4 and 8.7 fold at day 7, respectively, as compared with that precultured. The cells in the S phase increased at day 21. CONCLUSIONS: This culture system is able to expand hematopoietic cells of human umbilical cord blood and keeps them intact. The number of hematopoietic cells reached the highest level in the culture from day 7 to day 14, which is the optimal time for transplantation.

Antigens, CD↗

PubMed2000

[Studies on the subgenomic RNAs of hepatitis E virus].

Through labeling HEV RNAs with [32P]-phosphate, two subgenomic RNAs at 6.5 to 7.5 h post-infection, one subgenomic RNA at 8.5 to 10.5 h post-infection and none subgenomic RNAs were detected at 21 post-infection or in purified virus. Hybridization results illustrated that the HEV subgenomic RNAs form a 3' nested set which is situated at the 3' end of genome, but their 5' ends do not share a common leader sequence. UV transcription results showed that the HEV subgenomic RNAs were transcribed independently from its promote. Primer extension analysis suggested that the 5' end of large subgenomic RNA was mapped to the initiative region within RNA polymerase region, and the small subgenomic RNA was mapped to the intergenic region between ORF1 and ORF2.

Cell Line↗

PubMed2000

[mRNA expression of keratoepithelin in cornea after photorefractive keratectomy in rabbits].

OBJECTIVE: To investigate the roles of keratoepithelin(KE) during healing after photorefractive keratectomy (PRK). METHODS: 20 of 24 rabbits underwent bilateral 193 nm excimer laser photorefractive keratectomy to correct 10 diopters of myopia, and the other 4 rabbits as normal group. The mRNA levels of KE in corneas of the rabbits were determined by the in situ hybridization technique with a Digoxigenin labled probe. RESULTS: In normal group, there was no mRNA expression of KE in cornea. on 7, 14 days after operation, mRNA expression of KE was observed in epithelium and stroma of operation group, while on 28 days mRNA expression of KE was observed only in epithelium. CONCLUSION: KE was involved in the synthesis of extracellular matrix during healing after PRK and may play an important role in the development of haze by maintaining proper spacing among collagen fibrils.

Animals↗

PubMed2000

[Multiple factors analysis of myopic regression after photorefractive keratectomy].

PURPOSE: To investigate myopic regression after excimer laser photorefractive keratectomy(PRK) in patients with myopia. METHODS: PRK was performed to correct myopia errors from 1.00 D to 16.00 D diopters on 214 myopia eyes(121 patients). All eyes were divided into two groups: group I--1.00 D(-)-6.00 D (124 eyes), group II--6.25 D(-)-16.00 D(90 eyes). All the patients were followed up for two years. RESULTS: A Significant positive correlation was found between the regression and the extents of attempted correction. The rate of regression in mild to moderate myopia group was 9.7% while in highter group it was 27.8% (P < 0.005). The rate of regression of older age group in lighter myopia group was highter than that in younger case (P < 0.005). Relatively severe haze under the corneal epithelium often accompanies the regression. CONCLUSION: The main factors which caused the myopia regression after PRK was the extent of attempted correction, patients' age and corneal haze.

Adolescent↗

PubMed2000

[Analysis of refractive state after excimer laser photorefractive keratectomy in myopia].

OBJECTIVE: To evaluate refractive state after excimer laser photorefractive keratectomy (PRK) in patients with myopia. METHODS: 234 cases(391 eyes) followed up for two years were divided into two groups, group I: mild and moderate myopia(< or = -6.00 D), 228 eyes; group II: High myopia(> -6.00 D), 163 eyes. The refractive state of patients at three, six, twelve and twenty-four months postoperatively were monitored. RESULTS: At two years after photorefractive keratectomy (PRK), refractive regression (> -0.5 D), overcorrection(> 1.00 D), undercorrection(> 1.00 D), postoperative residual astigmatism postoperative astigmatism and hyperopia shift in group I were 1.7%, 4.4%, 5.7%, 12.8%, 7.4% and 7.5% respectively, while in high myopia group were 15.9%, 4.9%, 23.3%, 29.7%, 31.1% and 6.7% respectively. CONCLUSION: The results prove that photorefractive keratectomy is an effective, precise, stable and safe method for correction of mild and moderate myopia, but insufficient for high myopia.

Adolescent↗

PubMed1999

The peptide bond between E292-A293 of Escherichia coli leucyl-tRNA synthetase is essential for its activity.

Escherichia coli leucyl-tRNA synthetase (LeuRS) is a class I aminoacyl-tRNA synthetase that contains a large connecting polypeptide (CP1) inserted into its nucleotide binding fold, or active site. In this study, purified leucyl-tRNA synthetase was found to be cleaved between E292 and A293 in its CP1 domain. SDS-PAGE analysis showed peptides of 63 and 34 kDa in addition to the native 97.3 kDa synthetase. By internal complementation, the two peptides could form a 97.3 kDa complex similar to the native LeuRS. This complex could support the ATP approximately PP(i) exchange activity of LeuRS, but could not complement for aminoacylation. To study the function of the region around the bond of E292 and A293, four pairs of peptides resulting from different cleavage sites in CP1 were reconstituted in vivo. With the exception of the enzyme assembled from the E292-A293 cleavage site, all the reassembled LeuRSs catalyzed the aminoacylation of tRNA(Leu). Although the E292-A293-cleaved LeuRS could not catalyze aminoacylation, fluorescence titration revealed that its tRNA binding ability was almost identical to that of wild-type LeuRS. These results suggest that the region around E292-A293 may be responsible for maintaining the proper conformation of LeuRS required for the tRNA charging activity.

Acylation↗

PubMed1999

Multiple forms of p55PIK, a regulatory subunit of phosphoinositide 3-kinase, are generated by alternative initiation of translation.

A cDNA encoding p55PIK, one of the regulatory subunits of phosphoinositide (phosphatidylinositol) 3-kinase, was cloned from a cDNA library derived from the mouse mammary epithelial cell line C57MG. The cDNA coding for full-length p55PIK was transiently expressed in COS-7 cells. Western blot analysis of p55PIK expression using a specific antibody against p55PIK revealed that multiple protein products with different molecular masses were detected in COS-7 cell extracts. Experiments presented here demonstrate that multiple forms of p55PIK detected in COS-7 cells were produced by alternative initiation of translation. We also show that at least two in-frame start codons (AUG#2 and AUG#5) in p55PIK mRNA are used in COS-7 cells for the initiation of translation of p55PIK into proteins of 54 kDa and 50 kDa respectively. p55PIK mRNA was also alternatively translated into two proteins in PC cells, a mouse teratoma cell line, indicating that the alternative initiation of translation of p55PIK is not restricted to COS-7 cells. Results from immunoprecipitation and Western blot analysis showed that two forms (54 kDa and 50 kDa protein species) of p55PIK were detected in C57MG cells. Interestingly, when C57MG cells were treated with insulin, only p55PIK, but not p50PIK, bound to insulin receptor substrate-1 protein, providing evidence that different forms of p55PIKs may have specific distinct roles in signal transduction pathways.

Amino Acid Sequence↗

PubMed1999

A unified and quantitative receptor model for the microtubule binding of paclitaxel and epothilone.

[formula: see text] Paclitaxel and epothilone represent the two major classes of antimicrotubule agents that promote tubulin polymerization and, presumably, mitotic arrest during cell division. A common minireceptor binding site model at beta-tubulin has been constructed for these structurally divergent compounds. Utilizing 20 amino acids identified in photoaffinity labeling experiments, the 3-D model correlates measured and predicted Ki's with r = 0.99 and rms(delta Gcalc-delta Gexp) = 0.2 kcal/mol. In addition, the model predicts the affinity of compounds not used in the training set and explains much of the SAR for the paclitaxel and epothilone families.

Antineoplastic Agents↗