Biomedical subjects
Publications and source records attributed to X Xiao.
The manufacturing methods and testing results of the pneumatic left ventricular assist pump(L-Y pump) are introduced in this paper. The results demonstrate that L-Y pump is reliable, biocompatible and in keeping with the clinical requirements.
OBJECTIVE: To investigate mitochondrial DNA (mt-DNA) mutations in optic neuritis of unknown cause (ONUC) and to assess the practical value of mt-DNA mutation detection in etiologically and differentially diagnosing ONUC. METHODS: Thirty patients with ONUC were screened for mt-DNA mutations of nt11778, nt3460 and nt15257 by using SSCP, mutation-specific primer PCR and sequencing. RESULTS: mt-DNA mutations were found in twelve of thirty ONUC patients. All of the mutations were at nt11778 position, but no one at nt3460 and nt15257. CONCLUSIONS: Forty percent (12/30) of ONUC patients were caused by an mt-DNA mutation. Combined with other routine measures, screening for mt-DNA mutations in ONUC patients is of great significance in diagnosing ONUC etiologically and differentially.
OBJECTIVE: To determine the sensitivity and specificity of using a computer-photoscreener and non-cycloplegic retinoscopy in the detection of amblyopiogenic factors in nine to fifty months old infants and children. METHODS: Three hundred children, nine to fifty months old, were screened with the computer-photoscreener and non-cycloplegic retinoscopy. With a blinded standardized clinical assessment as the standard, an overall comparison of the sensitivity of and specificity results obtained with the two techniques was made. Photoscreen images on the computer monitor screen were reviewed and analyzed immediately by two independent observers for indicators of amblyopiogenic risk factors. Simultaneously, the results were compared to the findings of a full ophthalmologic examination. RESULTS: The computer-photoscreener revealed a sensitivity of 94.6% and specificity of 90.1%, and the non-cycloplegic retinocopy revealed a sensitivity of 85.7% and specificity of 81.0% for the detection of amblyopiogenic risk factors, including hyperopia (+2.75 D or more), myopia (-1.50 D or more), astigmatism (1.75 D or more), anisometropia (2.00 D or more), ocular misalignment (5 degrees or more), and media opacity (1.5 mm or more). CONCLUSIONS: The computer-photoscreener offers an opportunity to identify problems that limit vision, and could provide a feasible and sufficiently reliable screening technique in infants and preschool children to be screened successfully for amblyopiogenic risk factors.
OBJECTIVE: To observe the effect of intravascular laser irradiation of blood (ILIB) therapy on cellular immunity, change of T-lymphocyte subsets and humoral immunity in senile cerebral infarction patients of Kidney deficiency type. METHODS: Seventy-five patients were divided randomly into the ILIB group and the control group treated by conventional medicine (CM). Serum CD3, CD4, CD8, IgG, IgA, IgM, C3 and C4 levels of patients were determined before and after treatment for self-control and comparing between various groups and that of normal control. RESULTS: Before treatment, in patients of both groups, the levels of CD3, CD4, CD4/CD8, C3 were all lower than normal levels significantly, C4 and IgM higher than normal (P < 0.05, P < 0.01), the level of IgG lowered in patients inclined to Kidney-Yang deficiency and raised in those inclined to Kidney-Yin deficiency (P < 0.01). After treatment, in the ILIB group, CD3, CD4 and CD4/CD8 raised significantly (P < 0.05, P < 0.01), IgG and C3 varied towards normal control (P < 0.01, P < 0.05), and C4 lowered but without significance. In the control group, the indexes changed also toward normal but without significance except the change of IgG (P < 0.05). As for IgA and IgM, marked changes were not found in both groups in comparison between before and after treatment. CONCLUSION: ILIB therapy could bi-directionally regulate cellular and humoral immunity in senile cerebral infarction patients of Kidney deficiency type, which was similar to the function in supplementing Qi and invigorating Kidney of Chinese herbal medicine.
OBJECTIVE: To analyze the outcome of twenty-two years of cadaveric kidney transplantation and the predict factors impacting on graft survival. METHODS: The data of 1,180 cadaveric kidney graftings in 1,039 patients between October of 1977 and June of 1999 were summarized by calculation of patient and graft survival rates using Kaplan-Meier product limit estimates. 13 factors that may influence on graft survival were analyzed by the log-rank and Cox model. RESULTS: The total of 1-, 5-, 10-, 15-, and 20-year patient survival rates were 93.02%, 80.25%, 67.86%, 65.34% and 65.34%, and the corresponding graft survival rates 88.6%, 68.3%, 43.8%, 43.8%, and 32.8%, respectively. Graft half-life was (13.98 +/- 0.96) years. The longest survivor was 22 years after cadaveric kidney transplantation. The quality of life after grafting in 835 alive patients was improved apparently; 95% of them had a normal graft function and 85% returned to work. The result of multivariable analysis using Cox model showed that 8 factors of patient's age, grafting time, pretransplant blood transfusion, cold ischemia time, delayed graft function, time of normal graft function, immunosuppressive regimen, and acute rejection were very important to affect the graft survival. CONCLUSION: Cadaveric kidney transplantation is a successful and effective method to rescue the patients with end-stage renal disease.
Since 1998 the cardiac surgeons of WCUMS have performed modified maze procedure for treating the patients with rheumatic mitral valve disease accompanied with chronic atrial fibrillation (Af). In this study, echocardiography, especially Doppler Tissue Imager (DTI), was used to evaluate atria contraction and function of such patients before and after the operation. 14 rheumatic mitral disease patients, aged 27-60 years, were chosen; among them, 11 had mitral stenosis, 3 mitral regurgitation. The control group consisted of 16 cases, aged 24-67 years, with normal echocardiogram. Before and half-1 year after the operation, left atrium, left ventricle, right atrium and ventricle were measured, and cardiac function and posterior wall motion of left atrium were measured. Velocity of mitral valve annual and tricuspid valve annual was measured in DTI. The results showed: There was no age difference between the two groups. The motion of posterior wall of left atrium was 4.18 +/- 0.37 mm in the operation group, 4.09 +/- 0.29 mm in the control group (P > 0.05). No difference in velocity of mitral/tricuspid valve annual between the two groups was observed; 3 peaks of mitral valve annual were S 0.11 +/- 0.02, e 0.11 +/- 0.01, a 0.09 +/- 0.01 (m/s) in operation group, and S 0.08 +/- 0.00, e 0.10 +/- 0.01, a 0.08 +/- 0.01 (m/s) in control group, (P > 0.05, respectively); 3 peaks of tricuspid valve annual were S 0.10 +/- 0.01 vs 0.11 +/- 0.08, e 0.11 +/- 0.08 vs 0.10 +/- 0.01, a 0.10 +/- 0.10 vs 0.09 +/- 0.01 (m/s), (P > 0.05, respectively). The diameter of left atrium after operation in cases of mitral stenosis decreased significantly, compared with that before operation (P < 0.01). The diameter of right atrium after operation decreased significantly, compared with that before operation (P < 0.01). There was no significant change in right ventricle/left ventricle/EF and FS. The diameter of left atrium after operation in cases of mitral regurgitation decreased significantly, compared with that before operation (P < 0.01). The diameter of left ventricle after operation decreased significantly, compared with that before operation (P < 0.05). No significant change in right ventricle/right atrium/EF and FS was noted. The authors conclude the DTI, as a new diagnostic method in echocardiography, has high sensitivity and is less influenced when used to observe motion of atrium-ventricle annual influenced. It can avoid the error caused by deviation of blood displacement. In the rheumatic mitral valve disease patients who had mitral valve replacement and modified maze procedure, atrial contraction respores, the risk of thromboembolism decreases and prognosis improves. So the operation is worth doing.
The purpose of this study was to evaluate the preliminary results after prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis. 20 patients had received operation with expanded polytetrafluoroethylene(e-PTFE) as artificial chordade. The patients were followed up by means of echocardiography. The time of follow-up study varied from 4 to 18 months with a mean of 6 months. The left atrial, ventricular dimension as well as ventricular function were assessed. In addition, the length of artificial chorade and obstruction of left ventricular outflow track were observed. The results showed that left atrial diameter (LAD, from 57.59 +/- 13.51 mm to 47.05 +/- 9.55 mm), left ventricular end-diastolic dimension (LVEDD, from 46.23 +/- 12.56 mm to 42.41 +/- 10.86 mm), left ventricular end-systolic dimension (LVESD, from 33.50 +/- 10.20 mm to 29.68 +/- 8.40 mm) decreased (P < 0.01), and ejection fraction (EF, from 52.59 +/- 11.89% to 58.36 +/- 8.03%) increased (P < 0.05) after operation. There were no significant changes of fractional shortening (FS, from 29.23 +/- 8.99% to 31.05 +/- 6.08%). The length of artificial chorade ranged from 2.6 cm to 4.3 cm (the mean, 3.2 cm). There was no case of obstruction of left ventricular outflow track. It is believed that the result of preliminary echocardiographic observation on prosthetic valve replacement of preserving the subvalvular apparatus with artificial chorade for mitral stenosis is satisfactory.
OBJECTIVE: To observe the clinical effect of magnetic attachment with overdenture. METHODS: Ten subjects were selected and treated with Magnetic EX-600 retained mandibular complete overdentures. Each patient's masticatory function, overdenture retention force and abutment condition were measured at different periods and the statistics of each individual were compared respectively. RESULTS: Magnetic attachments can provide good retention for mandibular complete overdentures and improve the masticatory performance of the patients. What's more, the mobility and periodontal index of abutments were improved after 6 months. CONCLUSION: Magnetic EX-600 is very useful to improve the function of mandibular overdentures.
In the present paper, we studied the surface structure effect of Pt electrode modified with antimony and sulfur adatoms towards 1,3-Butanediol oxidation. The results demonstrated that the modification of Sb and S both inhibited the dissociative adsorption of 1,3-Butanediol into CO, which is the main source of self-poisoning in electrocatalysis of small organic molecules. At lower potentials, the principal oxidation pathway of 1,3-Butanediol on Pt/Sbad electrode is towards the production of C=O. However, at higher potentials, the products of CO2 increased. The presence of S(ad) inhibited the oxidation of 1,3-BD at low potentials(< 0.8 V), and yield mainly acid species as products at higher potentials(> 0.8 V).
HSF1 is the major heat shock transcriptional factor that binds heat shock element (HSE) in the promoter of heat shock proteins (Hsps) and controls rapid Hsp induction in cells subjected to various environmental stresses. Although at least four members of the vertebrate HSF family have been described, details of their individual physiological roles remain relatively obscure. To assess whether HSF1 exhibited redundant or unique in vivo functions, we created Hsf1(-/-) deficient mice. We demonstrate that homozygous Hsf1(-/-) mice can survive to adulthood but exhibit multiple phenotypes including: defects of the chorioallantoic placenta and prenatal lethality; growth retardation; female infertility; elimination of the 'classical' heat shock response; and exaggerated tumor necrosis factor alpha production resulting in increased mortality after endotoxin challenge. Because basal Hsp expression is not altered appreciably by the HSF1 null mutation, our findings suggest that this factor, like Drosophila Hsf protein, might be involved in regulating other important genes or signaling pathways. Our results establish direct causal effects for the HSF1 transactivator in regulating critical physiological events during extra-embryonic development and under pathological conditions such as sepsis to modulate pro-inflammatory responses, indicating that these pathways have clinical importance as therapeutic targets in humans.
Stem cell factor (SCF) is expressed as an integral membrane growth factor that may be differentially processed to produce predominantly soluble (S) (SCF(248)) or membrane-associated (MA) (SCF(220)) protein. A critical role for membrane presentation of SCF in the hematopoietic microenvironment (HM) has been suggested from the phenotype of the Steel-dickie (Sl(d)) mice, which lack MA SCF, and by studies performed in our laboratory (and by others) using long-term bone marrow cultures and transgenic mice expressing different SCF isoforms. Steel(17H) (Sl(17H)) is an SCF mutant that demonstrates melanocyte defects and sterility in males but not in females. The Sl(17H) allele contains a intronic mutation resulting in the substitution of 36 amino acids (aa's) in the SCF cytoplasmic domain with 28 novel aa's. This mutation, which affects virtually the entire cytoplasmic domain of SCF, could be expected to alter membrane SCF presentation. To investigate this possibility, we examined the biochemical and biologic properties of the Sl(17H)-encoded protein and its impact in vivo and in vitro on hematopoiesis and on c-Kit signaling. We demonstrate that compound heterozygous Sl/Sl(17H) mice manifest multiple hematopoietic abnormalities in vivo, including red blood cell deficiency, bone marrow hypoplasia, and defective thymopoiesis. In vitro, both S and MA Sl(17H) isoforms of SCF exhibit reduced cell surface expression on stromal cells and diminished biological activity in comparison to wild-type (wt) SCF isoforms. These alterations in presentation and biological activity are associated with a significant reduction in the proliferation of an SCF-responsive erythroid progenitor cell line and in the activation of phosphatidylinositol 3-Kinase/Akt and mitogen-activated protein-Kinase signaling pathways. In vivo, transgene expression of the membrane-restricted (MR) (SCF(X9/D3)) SCF in Sl/Sl(17H) mutants results in a significant improvement in peripheral red blood cell counts in comparison to Sl/Sl(17H) mice.
HIV-1 entry into cells involves formation of a complex between gp120 of the viral envelope glycoprotein (Env), a receptor (CD4), and a coreceptor. For most strains of HIV, this coreceptor is CCR5. Here, we provide evidence that CD4 is specifically associated with CCR5 in the absence of gp120 or any other receptor-specific ligand. The amount of CD4 coimmunoprecipitated with CCR5 was significantly higher than that with the other major HIV coreceptor, CXCR4, and in contrast to CXCR4 the CD4-CCR5 coimmunoprecipitation was not significantly increased by gp120. The CD4-CCR5 interaction probably takes place via the second extracellular loop of CCR5 and the first two domains of CD4. It can be inhibited by CCR5- and CD4-specific antibodies that interfere with HIV-1 infection, indicating a possible role in virus entry. These findings suggest a possible pathway of HIV-1 evolution and development of immunopathogenicity, a potential new target for antiretroviral drugs and a tool for development of vaccines based on Env-CD4-CCR5 complexes. The constitutive association of a seven-transmembrane-domain G protein-coupled receptor with another receptor also indicates new possibilities for cross-talk between cell surface receptors.
To test the hypothesis that inefficient interactions of CXCR4 with CD4 and gp120 could affect HIV-1 entry, we incubated macrophages, monocytes, and lymphocytes with gp120 and coimmunoprecipitated CD4 by using anti-CXCR4 antibodies. CD4 was efficiently coimmunoprecipitated in lymphocytes and monocytes but not in macrophages. Overexpression of CD4 in macrophages resulted in detection of CD4-CXCR4 and gp120-CD4-CXCR4 complexes in parallel with the restoration of macrophage fusion susceptibility. These results suggest a mechanism of resistance to entry of some X4 HIV-1 strains into macrophages and a method for dissection of the initial stages of HIV entry.
Telomere shortening may reflect the total number of divisions experienced by a somatic cell and is associated with replicative senescence. We found that the average rate of telomere shortening in peripheral blood mononuclear cells (PBMCs) obtained longitudinally from nine different infants during the first 3 years of life (270 bp per year) is more than fourfold higher than in adults and does not correlate with telomerase activity. These results show that the rate of telomere loss changes during ontogeny, suggesting the existence of periods of accelerated cell division. Because human immunodeficiency virus (HIV) preferentially infects actively dividing cells, our observation suggesting accelerated cell division in children may provide an explanation for some of the distinctive pathogenic features of the HIV disease in infants, including higher viral loads and more rapid progression to acquired immunodeficiency syndrome (AIDS).
Cervical carcinoma is an AIDS-defining illness. The expression of folate receptors (FRs) in cervical carcinoma (HeLa-IU1) cells was modulated by stable transduction of FR cDNA encapsidated in recombinant adeno-associated virus-2 in the sense and antisense orientation (sense and antisense cells, respectively). Although sense cells proliferated slower than antisense or untransduced cells in vivo and in vitro in 2% (but not 10%) FCS, [methyl-3H]thymidine incorporation into DNA was significantly increased in sense cells in 10% serum; therefore, the basis for this discrepancy was investigated. The activity of thymidine kinase (TK) was subsequently directly correlated with the extent of FR expression in single cell-derived clones of transduced cells. This elevated TK activity was not a result of recruitment of the salvage pathway based on the presence of adequate dTTP pools, normal thymidylate synthase (TS) activity, persistence of increased thymidine incorporation despite the exogenous provision of excess 5,10-methylene-tetrahydrofolate, and documentation of adequate folates in sense cells. The increase in TK activity conferred significant biological properties to sense cells (but not antisense or untransduced cells) as demonstrated by augmented phosphorylation of 3'-azido-3'-deoxythymidine (AZT) and concomitantly greater sensitivity to the cytotoxic effects of AZT. Conversely, sense cells were highly resistant to methotrexate, but this was reversed by the addition of AZT. The direct correlation of FR expression and TK activity indicates a previously unrecognized consequence of FR overexpression.
Organotypic cultures of rat hypothalamic slice cultures were successfully transduced using adeno-associated viral vectors. Using nuclear-targeted Lac-Z as the reporter gene, transduction was found to be very effective, occurring in as high as 89% of a specific cell type, the oxytocin neurons, present in the cultured explants. These transduction levels were not accompanied by any deleterious effects in the cultured cells 7 days after transduction. Such an in vitro approach should be valuable for the study of cell-specific gene expression in neurons in the central nervous system for which there are no homologous (surrogate) cell lines.
The clinical application of contrast enhanced (CE) MR was evaluated. A total of 66 CE MR portograms were obtained by performing fast imaging with steady procession (FISP) technique on a 1.5-T Siemens magnetom vision. A maximum intensity projection algorithm was also employed to include all vessels in a single image. The patency of portal venous system, the presence and extent of varices were also evaluated. The results showed that all images had diagnostic quality. Main portal vein (MPV) and its 4th-6th level intrahepatic branches were visualized in 10 normal persons serving as control. The diameter of MPV, splenic vein and superior mesenteric vein was 1.02 +/- 0.21, 0.8 +/- 0.15, 0.8 +/- 0.26 cm respectively, which were significantly lower than that in portal hypertension patients (1.38 +/- 0.27, 1.26 +/- 0.18, 1.24 +/- 0.18 cm, respectively). In 23 preoperative cases of portal hypertension, dilated portal vein and tortuous enlarged splenic vein were found in 23 cases; esophageal and coronary varices in 12 and 19 cases, respectively. In 7 postoperative re-examined cases with portal hypertension, the flow velocity and flow of MPV were decreased in all cases and esophageal varices could still be observed in 3 cases. New vessels appeared in the great curvature of stomach in 2 cases. In 20 cases of liver carcinoma, occlusion of MPV or its intrahepatic branches were showed in 14, compression and dislocation of intrahepatic portal vein were found in 6. In other 6 cases, 2 were splenic venous thrombosis and 4 were tumors in the intestine or retro-peritoneum. It is concluded that three-dimensional CE MR portography is an accurate technique for evaluating the portal venous system. It is a reliable and noninvasive technique that can provide important information for the evaluation of patients' condition before TIPSS and liver transplantation.
PURPOSE: This study was designed to observe whether estrogen can enhance the proliferation of hemangioma vascular endothelial cells (VECs) and, if so, the possible inhibiting effect of tamoxifen against estrogen. METHODS: Two skin hemangiomas with positive estrogen receptor staining from 2 infants were used for VECs culture. Based on different culture conditions and treatment, the subcultured VECs of passage 3 derived from a hemangioma were divided into 5 groups: group 1, control without endothelial cell growth supplement (ECGS) in medium; group 2, estradiol (E2) without ECGS; group 3, control with ECGS in medium; group 4, E2 with ECGS; group 5, E2 and 4OH-tamoxifen with ECGS. Cell counts and 3H-TdR incorporations were determined on culture days 3, 6, and 9. VECs from the other hemangioma were divided into 2 groups: group 3, control with ECGS in medium; group 4, E2 with ECGS. RESULTS: At the end of the 9-day study, the cell counts (x10(4)/mL) of the 5 groups were 6.31+/-1.24, 6.52+/-1.08, 15.62+/-1.88, 36.77+/-3.96, and 6.88+/-1.20, respectively. 3H-TdR incorporations (cpm) were 511+/-127, 538+/-26, 1,350+/-67, 2,729+/-145, and 575+/-64, respectively. The results of the other hemangioma were similar to those of the first one. Our data showed that without ECGS in medium, E2 had no effect on the proliferation of VECs (group 1 v group 2, P>.05); with ECGS in medium, E2 yielded a 2-fold increase in the proliferation of VECs (group 3 v group 4, P<.01); when 4OH-tamoxifen was added, the proliferation of VECs was suppressed dramatically (group 4 vgroup 5, P<.01). CONCLUSIONS: Estrogen in vitro can promote the proliferation of hemangioma VECs. This promoting effect of estrogen may depend on certain growth factors, which can be inhibited by tamoxifen.