Biomedical subjects
Publications and source records attributed to X Liang.
Modified DNA carrying an azobenzene was successfully applied to the photo-regulation of DNA/RNA hybridization. When the azobenzene was isomerized from trans- to cis-form on UV-irradiation, the melting temperature of the duplex was significantly lowered. This process was totally reversible so that the Tm increased by cis-->trans isomerization induced by visible light irradiation.
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A potent and selective inhibitor of the osteoclastic V-H(+)-ATPase, (2Z,4E)-5-(5,6-dichloro-2-indolyl)-2-methoxy-N-(1,2,2,6, 6-pentamethylpiperidin-4-yl)-2,4-pentadienamide (SB 242784), was evaluated in two animal models of bone resorption. SB 242784 completely prevented retinoid-induced hypercalcemia in thyroparathyroidectomized (TPTX) rats when administered orally at 10 mg/kg. SB 242784 was highly efficacious in the prevention of ovariectomy-induced bone loss in the rat when administered orally for 6 months at 10 mg/kg/d and was partially effective at 5 mg/kg/d. Its activity was demonstrated by measurement of bone mineral density (BMD), biochemical markers of bone resorption, and histomorphometry. SB 242784 was at least as effective in preventing bone loss as an optimal dose of estrogen. There were no adverse effects of compound administration and no effects on kidney function or urinary acidity. Selectivity of the inhibitor was further studied using an in situ cytochemical assay for bafilomycin-sensitive V-H(+)-ATPase using sections of osteoclastoma and numerous other tissues. SB 242784 inhibited the osteoclast enzyme at 1,000-fold lower concentrations than enzymes in any of the other tissues evaluated. SB 242784 demonstrates the utility of selective inhibition of the osteoclast V-H(+)-ATPase as a novel approach to the prevention of bone loss in humans.
Targeted gene disruption studies in the mouse have demonstrated crucial roles for the Brn3 POU domain transcription factor genes, Brn3a, Brn3b, Brn3c (now called Pou4f1, Pou4f2, Pou4f3, respectively) in sensorineural development and survival. During mouse retinogenesis, the Brn3b gene is expressed in a large set of postmitotic ganglion cell precursors and is required for their early and terminal differentiation. In contrast, the Brn3a and Brn3c genes, which are expressed later in ganglion cells, appear to be dispensable for ganglion cell development. To understand the mechanism that causes the functional differences of Brn3 genes in retinal development, we employed a gain-of-function approach in the chick embryo. We find that Brn3b(l) and Brn3b(s), the two isoforms encoded by the Brn3b gene, as well as Brn3a and Brn3c all have similar DNA-binding and transactivating activities. We further find that the POU domain is minimally required for these activities. Consequently, we show that all these Brn3 proteins have a similar ability to promote development of ganglion cells when ectopically expressed in retinal progenitors. During chick retinogenesis, cBrn3c instead of cBrn3b exhibits a spatial and temporal expression pattern characteristic of ganglion cell genesis and its misexpression can also increase ganglion cell production. Based on these data, we propose that all Brn3 factors are capable of promoting retinal ganglion cell development, and that this potential may be limited by the order of expression in vivo.
Two approaches are described for stably conjugating peptides, proteins and oligonucleotides onto plasmid DNA. Both methods use a peptide nucleic acid (PNA) clamp, which binds irreversibly and specifically to a binding site cloned into the plasmid. The first approach uses a biotin-conjugated PNA clamp that can be used to introduce functional biotin groups onto the plasmid to which streptavidin can bind. Atomic force microscopy images of linearized plasmid show streptavidin localized at the predicted PNA binding site on the DNA strand. Peptides and oligonucleotides containing free thiol groups were conjugated to maleimide streptavidin, and these streptavidin conjugates were bound to the biotin-PNA-labeled plasmid. In this way, peptides and oligonucleotides could be brought into stable association with the plasmid. A second approach used a maleimide-conjugated PNA clamp. Methods are described for conjugating thiolated peptides and oligonucleotides directly to the maleimide-PNA-DNA hybrid. This straightforward technology offers an easy approach to introduce functional groups onto plasmid DNA without disturbing its transcriptional activity.
OBJECTIVE: To investigate the treatment options of clomiphene(CC)-resistant polycystic ovary syndrome (PCOS) related infertility. METHODS: Fifty-nine PCOS patients with CC resistant-anovulation were accepted and treated by the following three protcols: (1) follicle-stimulating hormone (FSH) group, 49 cycles; (2) FSH + pulsatile gonadotropin-releasing hormone(GnRH) group, 13 cycles; (3) conventional in vitro fertilization (IVF)-embryo transfer (ET) group, 19 cycles. Suppressive treatment on serum luteinising hormone (LH) and testosterone (T) levels was given in the first and second groups in advance. Serum estradiol level; pregnancy rate; miscarriage rate, ovarian hyperstimulation syndrome (OHSS) and multiple pregnancy rate were compared among the three groups. RESULTS: The pregnancy rate in FSH group, FSH + GnRH group and IVF-ET group were 37%, 54% and 22% respectively. The highest rate and multiple pregnancy rate was found in IVF-ET group. CONCLUSION: The rationale treatment options for CC-resistant PCOS related infertility was the addition pre-suppressive treatment, low-dose FSH stimulated regimen subsequent pulsatile GnRH infusion. IVF were only accepted after failure with gonadotropin therapy.
OBJECTIVE: To study the biological effect of arsenic trioxide (As2O3) on human cervical cancer SiHa cells and SiHa cells overexpressing bcl-2 gene. METHODS: SiHa cells with overexpression of Bcl-2 (SiHa-Bcl2 cells) were established by transfecting SiHa cells with Bcl-2 expression vector. The sensitivities of SiHa and SiHa-Bcl2 cells to As2O3 were determined using MTT (Thiazolyl blue) reduction and colony forming ability assay, morphological analysis, flow cytometric analysis, DNA agarose gel electrophoresis, in situ cell death detection (TUNEL), Northern blot, RT-PCR and Western blot. RESULTS: As2O3 inhibited the growth of SiHa cells and induced G2/M arrest and apoptosis of the cells. RT-PCR and Western blot analysis revealed that As2O3 induced SiHa cell apoptosis possibly via inhibiting the expression of HPV16 E7 and decreasing the expression of c-myc. However, we found that SiHa-Bcl2 cells partly resisted As2O3 induced apoptosis, which might be related to the prevention of the down-regulation of HPV16 E7 and c-myc gene expression. Nevertheless, As2O3 at a high concentration could still induce apoptosis of SiHa-Bcl2 cells mainly via decreasing Bcl-2 expression and slightly inhibiting viral gene expression. CONCLUSION: As2O3 is an inducer of the apoptosis of human cervical carcinoma cells and the cells overexpressing Bcl-2 can partly resist As2O3 induced apoptosis, but the exact mechanism is unclear.
OBJECTIVE: To study the role of platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) in the development of proliferative vitreoretinopathy (PVR). METHODS: Immunohistochemical localization was performed on frozen sections of the epiretinal or subretinal membranes from 21 PVR patients using! monoclonal antibodies against PDGF and bFGF and the streptavidin peroxidase system. RESULTS: PDGF was expressed in 15 of 21 specimens (71.4%), and bFGF was expressed in 14 specimens (66.7%). Different cell density was seen in different types of epiretinal membranes. The cell density of vascular membranes induced by PDR and Eales disease was the highest (> or = 61 cells/field, x 1000); nonvascular membranes induced by PVR or traumatic PVR had moderate cell density (31-60 cells/field); and the macular membrane had the lowest cell density (< or = 30 cells/field). CONCLUSION: The presents of PDGF and bFGF in PVR tissues suggest that PDGF and bFGF may play an important role in the development of PVR.
OBJECTIVE: To investigate the relation between osseointegration and stability of three kinds of implants used as orthodontic anchorage in dogs. METHODS: HA-coated, titanium coated, and uncoated titanium implants were inserted into each femur of two dogs. After heal period of three months, the orthodontic force of 200 g was applied by means of Ni-Ti springs, which were connected to the two adjacent implants, for two months. The position change of implants was measured and calculated. The shear bond strength of interface between implant and bone was measured with push-test. The interface was observed with scanning electronic microscope. RESULTS: The distance changes of HA-coated, T-coated and uncoated groups were (-0.50 +/- 1.78) mm, (-0.05 +/- 1.76) mm and (0.29 +/- 1.77) mm, respectively, which showed no statistical difference. The shear strength values were (2.88 +/- 0.55) MPa, (1.89 +/- 0.81) MPa and (2.14 +/- 0.49) MPa, respectively. HA-coated implant contacted with bone closely and the bond strength was the highest. The other two implants were found no significant difference in bond strength. CONCLUSION: The osseointegration was found at the interface among all three kinds of implants and bone and no displacement was found during application of clinical orthodontic force.
OBJECTIVE: To evaluate the prognostic factors of chronic myeloid leukemia (CML). METHODS: Survival curves were plotted according to the Kaplan-Meier method. Variables associated with prognosis were analyzed by Logrank test. A multivariate analysis of prognostic factors was performed using stepwise Cox model. RESULTS: Of the total 158 patients, the median survival time was 1,480 days. 5 years survival rate was 47.1% (95% CI, 36.7% - 56.9%). 10 years was 24.8% (95% CI, 15.0% - 35.8%). The predominant blastic crisis type is myeloblastic, myelomonocytic or monocytic(77.5%). The period from chronic phase to blastic phase was equal in myelosuppressive therapy group, non- myelosuppressive therapy group or altretamine (HMM) group. After evaluated by stepwise Cox's regression model, age>or=50 years, bone marrow blasts>or=0.05, bone marrow basophilic>or=0.05, Ph chromosome negative and HMM treatment were associated with poor prognosis. Hydroxyurea was always associated with longer survival. CONCLUSION: Age, Ph chromosome, bone marrow blasts and basophilic, and various treatment affected the survival of CML.
OBJECTIVE: With Helios gene gun, the report genes EGFP and Lac-Z were transfected to several cultured mammalian tumor cell lines in vitro and mice skin in vivo, respectively. A stable long time exogene's expression were got. Then, the pWRG3142, which carried mGM-CSF gene was delivered to the abdominal skin of C57BL/6 mice using gene gun. Pathological sections showed the local transproteins' expression companying with a profound inflammation reaction characterized by neutrophilic infiltration. ELISA assay of transfected mouse's serum sample indicated a high improvement of transgenic proteins level, which demonstrated that transgenic GM-CSF secreted from treated skin into the bloodstream effectively. In B16 melanoma tumor model, mice immunized with mGM-CSF expression plasmids could be partially protected from 1 x 10(5) B16 cells challenge and exhibited a drastically reduced tumor growth rate. Finally, we conclucled that exogenes could be transfected into cultured cell lines and mice skin effectively by gene gun technology, and gene gun mediated in vivo delivery of GM-CSF cDNA should be further developed for potential clinical testing as an approach for human cancer gene therapy.
OBJECTIVE: To evaluate the therapeutic efficiency of combining p53-expressing adenovirus with chemotherapy agents on GLC-82 human lung adenocarcinoma cells. METHODS: Human lung adenocarcinoma cell line GLC-82 was transfected with adenovirus-mediated p53 gene (Ad-p53) combining with administration of either kind of chemotherapeutic agents-cisplatin (CDDP) and arsenic trioxide (As(2)O(3)). The cell growth, morphological changes, cell cycle, apoptosis and molecular changes were measured using cell counting, reversmicroscope, flow cytometry, TUNEL, RT-PC, immunocytochemical assays, and in vivo therapy experiments to evaluate the therapeutic efficiency of such combined regimen. RESULTS: Ad-p53 transfer and CDDP (or As(2)O(3)) administration to GLC-82 cells could exertubstantially stronger therapeutic effects than the single agent treatment. Especially in in vivo experiments, combined administration of Ad-p53 and CDDP induced almost complete tumor remission (89.0%) compared to the partial tumor remission induced by single agent (43.9% or 57.3%). Moreover, delivery of Ad-p53, or administration of minimal-dose CDDP or As(2)O(3) or combined regimen could induce massive apoptosis of GLC-82 cells. Cell cycle analysis demonstrated that administration of CDDP or As(2)O(3) remarkably arrested GLC-82 cells in G(2)/M prior to apoptotic cell death. When treated with combined regimen, cells were arrested in G(2)/M to a greater extent prior to apoptotic cell death. CONCLUSION: After introduced into GLC-82 cells, Ad-p53 shows enhanced therapeutic efficiency for GLC-82 cells when combined with CDDP or As(2)O(3).
OBJECTIVE: To comprehend current status of injury in the residents of Shijiazhuang city and to lay a foundation for prevention from injury. METHODS: A retrospective study on injury in the 21,544 residents of two and six rural villages was conducted by multi-stage stratified sampling. RESULTS: Standardized incidence rate of injury was 4.21% in Shijiazhuang city, higher in the rural than in the urban areas and higher in men than in women. The top three causes of injuries were traffic accidents, falls and poisoning. Traffic accidents and poisoning ranked the first place in the urban areas and in the rural areas, respectively. Falls occurred mostly in those aged less than 14 years and more than 60 years. Gas poisoning and traffic accidents occurred more often in those aged 15 - 34 years and traffic accidents ranked the first in the age group of 35 - 59 years old. Standardized mortality rate of injury was 48.78 per 100,000, higher in the rural than in the urban areas. Standardized mortality rate of suicide was the highest with 23.21 per 100,000 in the countryside and that of traffic accidents ranked the next. In average, 22 years of potential life lost, 17 work years of potential life lost and nine valued years of potential life lost for each death were caused by injury. Disability rate caused by injury was 1.1 percent. Direct economic loss for each case with injury cost 679.98 RMB yuan. Incidence rate for traffic accidents ranked the highest and the most severe in all injuries. CONCLUSION: Injury has become an important public health problem harmful to the people's health.
OBJECTIVE: To evaluate the effects of PHB membrane around dental titanium implants used in guided bone regeneration technique. METHODS: Endosseous cylindrical implants were placed in dogs' mandibles after extraction of all the mandibular premolars and the first molars immediately. Ideal implant placement sites were modified by creating standardized 3 mm x 5 mm facial dehiscent defects. The defects were covered with PHB membrane and titanium membrane respectively, then the membranes were fixed on the periosteum by sutures, and the remainder served as controls. Tissue closure was achieved with mattress and interrupted single sutures, and antibiotic injection was given to the dogs in the following 3 days. The dogs were divided into three groups according to the healing time of 1, 2 and 3 months, then the three groups of dogs were sacrificed. After that, tissue blocks containing the implants and the control ones were removed and studied by gross observation, X-ray radiograph and fluorescence microscope, and the surfaces of the membranes were observed by scanning electron microscope. The specimen used for light microscope study were fixed with 10% formaldehyde for 24 hours, and decalcified with 0.5 mol/L EDTA for 2 weeks. After the titanium implants were carefully removed, the tissue blocks were embedded into the paraffin wax, and the sections were obtained. RESULTS: The PHB membrane degraded slowly and partly 3 months after placement, and the biodegradable property of the PHB membrane deserved a longer period of study; The bone defects covered with PHB and titanium membrane were filled with much more new bone than that of the control group. CONCLUSION: PHB membrane can enhance bone formation and can be used for guided bone regeneration.
OBJECTIVE: To investigate the physical properties of titanium alloy fabricated with vacuum-sintered powder metallurgy. METHODS: The titanium powders of three different particle sizes(-160mesh, -200 - +300mesh, -300mesh) were selected, and mixed with copper and aluminum powder in different proportions. Two other groups were made up of titanium powder(-200 - +300mesh) plated with copper and tin. The build-up and, condensation method and a double-direction press with a metal mold were used. The green compacts were sintered at 1000 degrees C for 15 minutes in a vacuum furnace at 0.025 Pa. In the double-direction press, the specimens were compacted at the pressure of 100 MPa, 200 MPa and 300 MPa respectively. Then the linear shrinkage ratio and the opening porosity of the sintered compacts were evaluated respectively. RESULTS: 1. The linear shrinkage ratio of specimens decreased with the increased compacted pressure(P < 0.05). There was no significant difference among the linear shrinkage ratios of three different titanium powders at the same compacted pressure(P > 0.05), but that of titanium powder plated with copper and tin was higher than those of other specimens without plating(P < 0.05). 2. The opening porosity of specimens decreased with the increased compacted pressure(P < 0.05). Three different sized particle of titanium powder did not affect the opening porosity at the same compacted pressure(P > 0.05). CONCLUSION: The composition of titanium-based metal powder mixtures and the compacted pressures affect the physical properties of sintered compacts. Titanium powder plated with copper and tin is compacted and sintered easily, and the physical properties of sintered compacts are greatly improved.
OBJECTIVE: To quantitatively study basic fibroblast growth factor (bFGF) in the vitreous of proliferative vitreoretinopathy (PVR) in order to understand the role of bFGF in the development of PVR. METHOD: High sensitive sandwich enzyme immunoassay technique (ELISA) was used to measure bFGF level in vitreous of normal eyes, the eyes of PVR-C or PVR-D grade, eyes of vitreous hemorrhage and the serum levels of bFGF in PVR-D patients. RESULTS: The levels of bFGF in the vitreous were: median 5.20 ng/L, quartile 15.47 ng/L in 20 normal eyes; median 3.12 ng/L, quartile 10.48 ng/L in 35 PVR-C eyes; median 46.56 ng/L, quartile 113.96 ng/L in 26 PVR-D eyes; median 1.40 ng/L, quartile 6.25 ng/L in 25 vitreous hemorrhage eyes. The vitreous bFGF level in PVR-D group was significantly higher than that in the normal group, PVR-C group and vitreous hemorrhage group (P < 0.01). The mean of serum-bFGF level was 18.33 +/- 3.39 ng/L. The vitreous bFGF level of PVR-D group was significantly higher than serum-bFGF level (P < 0.01). And the vitreous-bFGF level in PVR-D group was significantly higher in larger retinal tear subgroup. CONCLUSION: The results suggested that bFGF is involved in the development of PVR.
PURPOSE: To explore the relationship between degree of retinopathy and degree of gestosis, hypertension, and fetal death rate by examing eye fundus of 115 gestosis patients. METHOD: We compared the degree of retinopathy with the degree of gestosis, the degree of hypertension, and the fetal death rate respectively. RESULTS: The degree of retinopathy is postively related with the degree of gestosis, the degree of hypertension and the fetal death rate. CONCLUSION: Eye fundus examination in gestosis patients is an significant guideline for clinical treatment.
OBJECTIVE: To investigate the change of gastric solid emptying at different stages in diabetic rats, and the effect of Chinese traditional medicine(CTM) on gastric emptying. METHODS: 40 Wistar rats were randomly divided into three groups: CTM treated diabetic(15 rats), untreated diabetic(15 rats) and control(10 rats). Diabetes was induced by i.p. of streptozotocin(STZ), 65 mg/kg. CTM, 3.75 g/kg daily (consisting of Dan shen, Fu Ling mainly which functioned as Huo xue hua yu and Bu shen) was administrated in treated diabetic rats. Blood glucose and body weights were measured weekly. 12 and 24 weeks after induction of diabetes, gastric emptying was examined with scintigraphy for 240 min (30 min interval). A test meal (42 kJ) labeled with 99mTc-SC(2.96 x 10(5) Bq) was provided. RESULTS: (1) There were no significant differences in total gastric retention rate and T 1/2 among three groups at 12 weeks. (2) The lag phase of total stomach in DM-B was (41.56 +/- 8.39) min, shorter than in control's (67.50 +/- 9.09) min, (P < 0.05). (3) The proximal gastric retention rate of 12-week diabetes at 90 min were (38.2 +/- 6.2)% (vs control, P < 0.01), (16.0 +/- 7.9)% (vs control, P < 0.01), and (61.9 +/- 3.5)%; and of 24-week at 120 min were (21.3 +/- 6.8)% (vs control, NS), (48.5 +/- 8.2)% (vs control, P < 0.05, vs treated diabetes, P < 0.01), (28.3 +/- 6.4)% in treated, untreated and control group respectively. (4) There was negative correlation between blood glucose and gastric retention rate (r = -0.62, P < 0.05). CONCLUSION: (1) The proximal gastric solid emptying was impaired in diabetic rats, there was significantly accelerated in 12-week and slowed down in 24-week compared with control. (2) CTM could modify these impairment. (3) Hyperglycemia had positive correlation to gastric emptying in animal model, which might explain the clinic presentations of patients with diabetes in early stage.