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Biomedical subjects

L Gao

Publications and source records attributed to L Gao.

At least 55 records · Page 3Linked to original sources
PubMed2001

Exploiting pattern and sustainable development of marginal lands in the Three Gorge Reservoir Areas.

This paper studied the distribution and utilization status, reasonable exploitation patterns and potential productivity, and sustainable development of marginal lands in the Three Gorge Reservoir Areas. It has been pointed that problems of the soil fertility degradation, poor productivity in crop lands, natural disasters and environmental deterioration existed in all the exploited marginal lands. In order to maintain the sustainability of the marginal lands, following measure have been proposed: prohibiting cultivation in the crop lands with a slope more than 25 degrees, restoring vegetation in the slope more than 25 degrees, strengthening the basic agricultural construction, establishing the production base of woody feeds and oils, establishing a multi-dimensional management model with reasonable structure and optimum function for forestry, agriculture and fishing.

Agriculture↗
PubMed2001

[Adenovirus-mediated transfer of human wild-type p53, GM-CSF, and B7-1 genes efficiently produces growth suppression and apoptosis of hepatocellular cells in vitro].

OBJECTIVE: To investigate the tumor suppressor activity of recombinant adenovirus vector expressing the human wild-type p53, GM-CSF, and B7-1 proteins (designated as BB-102) in human hepatocellular carcinoma cells (HCC) in vitro. METHODS: The wild-type p53 BEL-7402, mutant p53 HLE, and HuH-7 HCC cell lines were infected with BB-102 at MOI of 50 in vitro. Immunohistochemical assay was used to determine p53 expressed by BB-102. Tumor suppressor activity of the expressed p53 was identified by terminal deoxynucleotidy I transferase (TdT) assay in BB-102-infected HCC cell lines. RESULTS: p53 protein was found to express in a dose-dependent manner in BB-102-infected HCC cell lines. The proliferation of HCC cell lines were suppressed significantly at the average rates of 58.5%, 81.5%, and 71.1% for BEL-7402, HLE, and HuH-7 respectively from 4 to 10 days, accompanying inducing apoptosis in BB-102-infected HCC cell lines. CONCLUSIONS: Besides the expression of B7-1 and GM-CSF, BB-102 is able to express p53 protein in independent manner and exerts its anti-tumor activity, which suggests that BB-102 may be useful for gene therapy against HCC in vivo.

Adenoviridae↗
PubMed2001

Effect and mechanism of electronic magnetic pulse on peripheral lymphocytes in dogs.

OBJECTIVE: To study the effects of electronic magnetic pulse (EMP) on peripheral lymphocytes in dogs and to explore the mechanisms of the biological effects of EMP. METHODS: T, TH and TS lymphocytes were estimated by acid phosphatase cytochemistry. Apoptotic lymphocytes and Bax and Bcl-2 proteins related to apoptosis were observed with in situ terminal labeling and immunocytochemistry. RESULTS: Peripheral T lymphocyte subpopulations decreased obviously after EMP irradiation with (2-12) x 10(4) V/m. Apoptotic percentages of lymphocytes increased with the elevation of EMP doses. Ten days after different intensity radiation, the Bax protein was found to be elevated in accord with the peak value of lymphocyte apoptosis. However, Bcl-2 protein decreased obviously. CONCLUSION: A definite field intensity EMP could induce injury to lymphocytes. Apoptosis induced by EMP is one of the main causes of peripheral lymphocyte death and leads to immunosuppression of the body. These results suggest that people should pay more attention to the injury caused by EMP, especially to the immunological functions of the body.

Animals↗
PubMed2001

[Prognostic influence of parapharyngeal space involvement in nasopharyngeal carcinoma].

OBJECTIVE: To explore the prognostic influence of parapharyngeal space involvement in nasopharyngeal carcinoma (NPC). METHODS: From Jan. 1987 to Dec. 1994, 197 previously untreated NPC patients were examined by CT scan. The prognostic factors ware evaluated by univariate and multivariate analyses on SPSS 8.0 software. RESULTS: The actual survival rate, disease-free survival rate and local failure-free rate were negatively affected by the presence of parapharyngeal space involvement (P = 0.0115, P = 0.0035, P = 0.0367). The 5-year actual survival rate, disease-free survival rate and local failure-free rate in patients without tumor invasion to parapharyngeal space was 87.9%, 88.0% and 96.9%, respectively. The survival rate in patients with tumor invasion to prestyloid space was 75.0%, 71.2% and 93.7%, respectively. That in patients with tumor invasion to poststyloid space was 60.5%, 57.7% and 86.8%, respectively. The 5-year distant metastasis-free survival rate was 88.1% in patients without poststyloid involvement as compared to 73.8% in those with poststyloid involvement. CONCLUSION: The survival and local tumor control are affected by parapharyngeal space involvement. Distant metastasis is more likely to occur when the tumor growth involves poststyloid space.

Adolescent↗
PubMed2001

[The CPBC types used for clinical choice and observation on their microstructure].

UNLABELLED: According to the primary properties of calcium phosphate bone cement (CPBCs), we have chosen certain types of them for use in cranioplasty and have observed the microstructure of their set bodies by means of SEM. Five kinds of CPBCs powder have been prepared, including: octacalcium phosphate precipitated hydroxyapatite (OCP-PHA) type, octacalcium phosphate hydroxyapatite (OCP-HA) type, octacalcium phosphate (OCP) type, calcium deficient hydroxyapatite (CDHA) type and hydroxyapatite (HA) type. The mixing liquids were deionized water and 0.25 M Na2HPO4/NaH2PO4 buffer solution. The setting time was measured by Gillmore method. The compressive strengths were measured using the TS-14 automatically measured instrument-II of single granule's compressive strength. The CPBC types used for clinical cranioplasty were defined according to Ginebra's Criteria of the CPBCs, and the ultrastructure of the set-bodies of the defined CPBC type was observed by SEM before and after its immersion in Ringer's Solution. RESULT: Two out of five CPBCs, OCP-PHA-CPBC and CDHA-CPBC were selected for clinical cranioplasty. Before and after they were immersed in Ringer's Sol., the SEM found their set-bodies to be structurally porous and to dissolve with the increase of immension time. These data indicate that OCP-PHA-CPBC and CDHA-CPBC are sufficient for the reconstruction of non-stress-bearing bone, and the porous structure of their set-bodies is advantageous to fibroplasty or fibrovasculization in their set bodies.

Bone Cements↗
PubMed2001

Peri-operative treatment of most severely head-injured patients.

OBJECTIVE: To summarize the peri-operative experience from 53 patients with traumatic head injuries with GCS score 3-5. METHODS: Fifty-three most severely head-injured patients with GCS score 3-5 were admitted to our department and treated operatively from Oct. 1994 to Jun. 1998 and the data were analyzed retrospectively. RESULTS: Thirty-seven cases (69.8%) survived, among them 28 (52.8%) had a good recovery or moderate disability, and 9 (17%) had severe deficits. The other 16 (30.2%) died after therapy. CONCLUSIONS: The prognosis of most severely head-injured patients could be improved by peri-operative treatment including premedical care, early evacuation of intracranial hematoma with large decompressive craniectomies, intracranial hypertension monitoring, moderate hypothermia therapy, effective prevention and treatment of cerebral vasospasm and complications.

Adolescent↗
PubMed2001

Outcome prediction in severe traumatic brain injury with transcranial Doppler ultrasonography.

OBJECTIVE: To investigate the value of transcranial Doppler (TCD) ultrasonography in evaluating the outcome of severe traumatic brain injury and to correlate the TCD values with intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring. METHODS: A prospective study was conducted to evaluate the contribution of TCD ultrasonography to neurological outcome in a series of 96 severe traumatic brain injury patients. The quantitative variables of TCD ultrasonography included the mean blood flow velocity of the middle cerebral artery (MCA) and pulsatility index within the first 24 hours of admission. The ICP and CPP values were a lso recorded. Outcome in 6 months postinjury was evaluated using the Glasgow Outcome Scale (GOS 4-5 was considered as "good" and GOS 1-3 as "poor"). RESULTS: The mean blood flow velocity of the MCA was larger than 40 cm/s in 30 (51%) patients with good outcome whereas it was less than 40 cm/s in 27 (73%) patients with poor outcome (P<0.025). The mean PI in cases of good outcome (34 patients, 57%) was lower than 1.5 whereas in poor outcome (30 patients, 83%) was higher than 1.5 (P<0.001). The correlations of ICP and CPP to pulsatility index were statistically significant (P<0.01). CONCLUSIONS: TCD ultrasonography is valid in predicting the patient's outcome of 6 months and correlates significantly with ICP and CPP values when it is performed in the first 24 hours of severe traumatic brain injury.

Adolescent↗
PubMed2001

Association of HIF-1alpha expression and cell apoptosis after traumatic brain injury in the rat.

OBJECTIVE: To explore the expression of hypoxia inducible factor-1alpha (HIF-1alpha) and the correlation between HIF-1alpha and apoptosis after traumatic brain injury. METHODS: Using experimental traumatic brain injury in the rats, the expression of HIF-1alpha was studied by immunohistochemistry in cerebral tissue, apoptotic cell death was evaluated with TUNEL (transferase-mediated X-dUTP nick end labeling), and double-labeled immunohistochemistry and TUNEL methods were used to investigate the relationship between HIF-1alpha and apoptosis. RESULTS: There was remarkable difference in the expression of H IF-1alpha between the experimental groups and the control groups (P<0.01), in the experimental groups, the expression of HIF-1alpha at 48 hours was highest; the evidence of apoptotic cell death after experimental traumatic brain injury was found by TUNEL; the apoptotic percentage increased or decreased according to the changes of the positive expression of HIF-1alpha (r=0.99). CONCLUSIONS: The results suggest that secondary brain ischemia plays a crucial role in apoptotic cell death after traumatic brain injury; HIF-1alpha can prompt apoptotic cell death after experimental traumatic brain injury.

Animals↗
PubMed2001

[Inhibitory effects of melatonin on the development of 17-beta-estradiol induced prolactinoma in relation to plasma prolactin and peroxidative lipid contents].

In the present study, we have examined inhibitory effects of melatonin on the development of pituitary prolactin-producing tumors (prolactinoma) induced by 17-beta-estradiol (E(2)) in vivo. The prolactinomas were established by implanting E(2)-laden silastic capsules subcutaneously in Sprague-Dawley male rats weighing 80 approximately 100 g. Melatonin (0.05, 0.25, 0.50, 1.00, and 2.00 mg/0.1 ml/rat) was administrated subcutaneously at l8:00 h for 90 days, beginning from d 7 prior to tumor induction. Controls were given equal volumes of 4 percent; alcohol in 0.9 percent; saline. Our results showed: (1) In control group and groups given respectively 0.05, 0.25, 0.50, 1.00 and 2.00 mg melatonin, the weight of prolactinoma was 115.0+/-71.0, 85.2+/-41.0, 58.9+/-24.1, 72.7+/-23.6, 79.3+/-56.1, 74.5+/-46.8 mg respectively; the plasma prolactin (PRL) content was 493.46+/-33.3, 373.78+/-26.5, 125.13+/-13.3, 201.79+/-11.2, 418.88+/-41.3, 281.94+/-36.4 ng/ml respectively; the plasma peroxidative lipid content was 1.21+/-0.23, 0.89+/-0.32, 0.92+/-0.27, 0.64+/-0.24, 0.41+/-0.14 and 0.43+/-0.21 delta233/ml respectively. (2) The correlation coefficients between tumor weight and plasma PRL content, tumor weight and plasma peroxidative lipid content, and plasma PRL content and plasma peroxidative lipid content were 0.8738, 0.5550 and 0.2141 respectively. These results indicate: (1) The dosages of 0.25 (P<0.01) and 0.50 (P<0.05) mg, but not 0.05 (P>0.05), 1.00 (P>0.05) and 2.00 (P>0.05) mg, melatonin significantly inhibited the development of the E(2)-induced prolactinoma and the secretion of PRL in comparison with the matched control. (2) The levels of 0.05 approximately 2.00 (P<0.05 approximately 0.00l) mg melatonin showed a dose-dependent antioxidative action. (3) There are positive correlation between tumor weight and plasma PRL content (P<0.05), but no correlation between tumor weight and plasma peroxidative lipid content (P>0.05), and plasma PRL content and plasma peroxidative lipid content (P>0.05). Therefore, our experiments demonstrate that the inhibition of the development of E(2)-induced prolactinoma by adequate dosage of melatonin may be related to the inhibitory effects of MLT on the secretion of PRL, but not to the antioxidative action of MLT.

Animals↗
PubMed2001

[The change of nerve growth factor and brain derived neurotrophic factor in neurons of cerebral cortex of adult rat following local ischemia].

OBJECTIVE: To acquire knowledge about the change of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) in neurons of cerebral cortex of adult rat following local ischemia. METHODS: Using specific antiserums of NGF and BDNF by immunohistochemical ABC method. RESULTS: NGF-like and BDNF-like immunoreactions distributed mainly in the neurons of the third and fifth layers in cerebral cortex. After local ischemia, the average gray degrees of NGF and BDNF in neurons of cerebral cortex both decreased on the operated side more than on the un-operated side. CONCLUSION: This experiment demonstrated that the levels of NGF and BDNF in neurons of cerebral cortex following ischemia were upregulated apparently, suggesting that NGF and BDNF may play an important role in the process of neurons' reaction after ischemia.

Animals↗
PubMed2001

[Expression of C-myc and N-myc protein in adulthood and childhood medulloblastomas and prognostic analysis].

OBJECTIVE: To detect the expression of C-myc and N-myc in medulloblastomas, the difference between adults and children, and the relation between expression and prognosis. METHODS: ABC immunostaining was used to detect C-myc and N-myc protein expression in 21 cases of adulthood medulloblastomas and 14 childhood cases. Follow-up materials were obtained to perform survival curve analysis. RESULTS: Of these 35 cases, 5 (4 children, 1 adult) showed C-myc positive expression. No N-myc expression was found. There was no relationship between expression and survival. CONCLUSION: C-myc may play a role in the tumorgenesis of medulloblastoma, especially in children, but it is of no prognostic significance. N-myc antigen may be lost during the fixation of specimens.

Adolescent↗
PubMed2001

[Inhibitory effect of melatonin on the development of pituitary prolactin-producing tumors induced by 17-beta-estradiol].

OBJECTIVE: To examine the inhibitory effect of melatonin (MLT) on the development of pituitary prolactin-producing tumors (prolactinoma) induced by 17-beta-estradiol (E2), in vivo, and explore MLT's oncostatic mechanisms. METHODS: The prolactinomas were established by implanting E2-laden silastic capsules subcutaneously in Sprague-Dawley male rats. MLT doses 0.05, 0.25, 0.50, 1.00, and 2.00 mg/rat were administrated separately to 5 groups subcutaneously starting seven days prior to tumor induction for 97 days. The matched controls were given equal volumes of 4% alcohol in saline. RESULTS: (1) The prolactinoma weights in 0.05, 0.25, 0.50, 1.00 and 2.00 mg MLT dose groups were 25.91% (P > 0.05), 48.78% (P < 0.01), 36.78% (P < 0.05), 31.04% (P > 0.05) and 35.22% (P > 0.05) respectively which were lower than that of control group; (2) The PRL mRNA levels of prolactinoma in 0.05, 0.25, and 0.50 mg MLT dose groups were 33.67% (P < 0.05), 25.51% (P < 0.05) and 41.84% (P < 0.01) respectively which were lower than that of control group as estimated by Northern Blot, and the in situ hybridization studies; (3) The DNA contents of prolactinoma in 0.05, 0.25 and 0.50 mg MLT dose groups were 40.73% (P < 0.001), 51.15% (P < 0.001) and 60.23% (P < 0.001) respectively which were lower than that of control group by laser scanning confocal microscopy; (4) Plasma peroxidative lipid contents in 0.05, 0.25, 0.50, 1.00 and 2.00 mg MLT dose groups were 26.45% (P < 0.05), 23.97% (P < 0.05), 47.11% (P < 0.001), 66.12%(P < 0.001) and 64.46% (P < 0.001) respectively which were lower than that of control group. The correlation coefficient between MLT doses and plasma peroxidative lipid contents was -0.8257 (P < 0.05). CONCLUSIONS: MLT in suitable doses is able to inhibit the development of E2-induced prolactinoma by inhibiting the expression of PRL gene and the DNA synthesis. The link between MLT antioxidative action and its inhibitory effect on development of prolactinoma should be further investigated.

Animals↗
PubMed2000

Suppression of ganglioside GD3 expression in a rat F-11 tumor cell line reduces tumor growth, angiogenesis, and vascular endothelial growth factor production.

Ganglioside GD3 is overexpressed in many types of tumors and may be associated with tumor progression and the development of metastatic potential. In our previous study (G. Zeng et al., Biochemistry, 38: 8762-8769, 1999), we established a subclone of the rat dorsal root ganglion-derived F-11 cells in which the expression of ganglioside GD3 was inhibited by stable transfection of the antisense vector against CMP-NeuAc: GM3 alpha2-8 sialyltransferase (GD3-synthase) gene. This cell line exhibits markedly reduced rate of tumor growth in vivo. Here, we further characterized the antisense-transfected cell line, and the results showed that these cells formed small, minimally vascularized tumors exhibiting extensive necrosis. In vivo Matrigel assay revealed reduced vascularization and low hemoglobin content in the antisense xenografts. Significantly fewer new vessels were found on the antisense xenografts and the skin around them than those on/around the xenografts formed by the sense-transfected and untransfected F-11 cells. The hemoglobin content of the antisense xenografts was much lower than that of the xenografts formed by the control cells. The reduced angiogenesis in the antisense xenografts was correlated with a decrease in vascular endothelial growth factor (VEGF) production. The expression of VEGF was suppressed in the antisense xenografts and the conditioned culture media of the antisense-transfected F-11 cells as determined by Western blotting analysis. This was further confirmed by immunohistochemistry of the tumors using antibodies against VEGF and platelet/endothelial cell adhesion molecule (PECAM-1). Therefore, our results demonstrate that reduced tumor growth in nude mice by suppression of GD3-synthase expression in F-11 cells results from minimal angiogenesis of the tumors through down-regulation of the VEGF expression, which indicates an important role for GD3 in tumor angiogenesis.

Animals↗
PubMed2000

Reduced cell migration, tumor growth and experimental metastasis of rat F-11 cells whose expression of GD3-synthase is suppressed.

We previously established a rat F-11 cell line whose expression of ganglioside GD3 was inhibited by stable transfection of the anti-sense vector against the GD3-synthase gene, showing that specific inhibition of GD3-synthase expression in tumor cells greatly reduced their growth rate in nude mice. Here, we report that down-regulation of GD3-synthase expression in anti-sense-transfected F-11 cells correlates with reduced cell migration and invasion in vitro and tumor growth and metastasis in vivo. When cultures were denuded of cells in a 1-mm-wide strip, the anti-sense-transfected F-11 cells migrated very slowly into the denuded area. Differences in migration between anti-sense-transfected cells and control parental cells were easily apparent. In vitro invasion assay of F-11 cells revealed a 3-fold decrease in invasion ability from the GD3-synthase-suppressed cells; colony formation in soft agar was not affected. Injection (i.v.) of control sense-transfected and untransfected F-11 cells resulted in multiple, large metastatic nodules in each of the 12 mice, whereas i.v. injection of anti-sense-transfected F-11 cells formed a single, small metastatic nodule in only 2 of the 8 nude mice. In addition, even if metastasis occurred, the anti-sense-induced metastatic nodules were much smaller than the metastatic nodules formed by control F-11 cells. These results demonstrate that suppression of GD3-synthase expression, which results primarily in a marked decrease in the concentration of ganglioside GD3, greatly reduces cell spreading, invasion and both the incidence and growth rate of experimental metastasis of F-11 cells.

Animals↗
PubMed2000

Adsorption of PBTCA on Alumina Surfaces and Its Influence on the Fractal Characteristics of Sediments.

The adsorption of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) on Al(2)O(3) powder has been studied as a function of pH and concentration. The adsorption density of PBTCA is found to decrease with an increase of pH. Zeta potential measurements show that the addition of PBTCA results in a dramatic increase in the absolute zeta potential, as well as a shift of the isoelectric point to the more acidic region. PBTCA considerably enhances the stability of the alumina suspension via an electrostatic mechanism. The surface properties of alumina suspensions are examined by using Auger electron microscopy and FTIR analysis. Chemical interactions take place at the solid/water interface by forming complexes between Al(3+) ions and PBTCA. The dispersing ability of PBTCA is believed to be related to its high adsorption ability and the high number of dissociable protons. The morphology of the sediments is observed with scanning electron microscopy. It is found that the sediment surfaces exhibit fractal characteristics. The fractal dimension values of sediments are correlated with PBTCA concentration in the experimental range. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Anti-Gal antibodies in humans and 1, 3alpha-galactosyltransferase knock-out mice.

BACKGROUND: Due to the absence of alphaGAL epitopes, humans and galactosyltransferase knock-out (GALT/ KO) mice express high levels of anti-Gal antibodies. We describe the properties of mouse anti-GAL antibodies. METHODS: Anti-GAL IgG antibodies were quantified by affinity purification. Antibody affinities and avidities were determined in direct binding and competition assays. Antibody-mediated rejection was investigated using hyperimmunized GALT/KO mice as recipients of GAL+ heart allografts. RESULTS: In young GALT/KO mice the levels of anti-GAL antibodies were low. Immunization of GALT/KO mice resulted in increased anti-GAL antibody expression. In mouse serum 0.6% of IgG was specific for alphaGAL compared to 0.5% in human serum. The avidity of purified mouse and human anti-GAL IgG was 30 and 6 nM, the affinity 15 and 50 microM, respectively. The isotype distribution in mouse and human anti-GAL IgG appeared to be similar to the isotype distribution in normal sera. The affinity of mouse and human anti-GAL IgM was 150 and 750 microM, respectively. Immunized GALT/KO recipients of GAL+ heart transplants rejected their grafts within 2 hr although nonimmunized GALT/KO mice retained their grafts for up to 6 days. Immunohistological examination of the rejected GAL+ hearts revealed massive deposition of IgM and IgG on endothelial cells of the graft with a concomitant deposition of complement. CONCLUSIONS: Our studies demonstrate that anti-GAL antibodies from immunized GALT/KO mice bind alphaGAL with an avidity/affinity similar to human anti-GAL antibodies and are able to induce hyperacute rejection of GAL+ heart allografts.

Animals↗