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Biomedical subjects

Feng Gao

Publications and source records attributed to Feng Gao.

At least 109 records · Page 6Linked to original sources
PubMed2006

[Effects of xuezhikang and simvastatin on cerebral ischemia-reperfusion injury in rat].

OBJECTIVE: To observe the effects of Xuezhikang and simvastatin on cerebral ischemia/reperfusion injury in rat, as well as the influences after intervention with L-NAME. METHOD: Rats were given orally with Xuezhikang and simvastatin or vehicle for 2 weeks, and then subjected to middle cerebral artery occlusion for 120 min using intraluminal filament model. L-NAME were injected into the lateral ventricles in half of the rats treated with Xuezhikang and simvastatin 45 min before the ischemia. The neurological deficits examinations were performed at 2, 24, 48 h after reperfusion. After the last examination the animals were sacrificed, the infarct volumes were determined by TTC staining, and MDA levels were also measured. RESULT: Xuezhikang and simvastatin both significantly reduced the infarct volume and improved the functional recovery when compared to vehicle. Xuezhikang and simvastatin both significantly decreased the MDA accumulation after reperfusion. L-NAME partially inhibited the protective effect of Xuezhikang but nearly completely abolished the protective effect of simvastatin. CONCLUSION: Xuezhikang has protective effects on ischemic brain damage in rats, which the beneficial effects are partly due to the statins components. The other components in Xuezhikang may also account for the neuroprotective effects, which is worth further investigations.

Animals↗
PubMed2006

[Influence and significance of preoperative intraarterial infusion chemotherapy combined with radiotherapy on survivin, p53 and Bax expression in low rectal carcinoma].

BACKGROUND & OBJECTIVE: Recently, neoadjuvant therapy has attracted more attention, but the influence of preoperative intraarterial infusion chemotherapy (PRAC) combined with radiotherapy on Survivin expression in rectal carcinoma is unclear. This study was to investigate the effect of PRAC or radiotherapy on Survivin, P53, and Bax expression in low rectal cancer. METHODS: A total of 60 patients with low rectal carcinoma were randomized into 3 groups: 19 received PRAC combined with preoperative radiotherapy (radiochemotherapy group), 15 received preoperative radiotherapy alone (radiotherapy group), and 26 received operation alone (control group). PRAC was performed using Seldinger technique. Preoperative radiotherapy was performed with a total dose of 20 Gy in 5 days, and superadded 30 Gy after operation. Control group received postoperative radiotherapy with a total dose of 50 Gy. The expression of Survivin, P53, and Bax was examined by immunohistochemistry. RESULTS: After neoadjuvant therapy, there was no significant difference in the positive rates of Survivin, P53, and Bax among the 3 groups. In radiochemotherapy group, the positive rate of Survivin was reduced from 63.16% before neoadjuvant therapy to 26.32% after operation (P<0.05), and the overexpression rate of P53 was reduced from 57.89% to 26.32% (P<0.05). In radiotherapy group, the overexpression rate of Survivin was reduced from 53.33% to 13.33% (P<0.05), but there was no significant change in the positive rate of P53. The positive rate of Bax was slightly increased after operation in above 2 groups. In these 2 groups, the median survival time was significantly longer in the patients with reduced Survivin expression than in those with increased Survivin expression (50.05 months vs. 42.61 months, P<0.01). Survivin expression was not obviously related to Bax and P53 expression (P>0.05). CONCLUSION: Neoadjuvant therapy could decrease the levels of P53 and Survivin expression, might enhance the level of Bax expression, and consequently accelerate cancer cell apoptosis and achieve a better short-term curative effect on low rectal cancer.

Adenocarcinoma↗
PubMed2006

[Effect of cyclosporine A, raloxifene and their combination on the reversion of multidrug resistance of K562/A02 line].

This study was aimed to investigate the reversible effect of cyclosporine A, raloxifene and their combination on multidrug resistance cell line K562/A02. The IC(50) (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method, the expression level of mdr-1 mRNA was assayed by RT-PCR, p-glycoprotein (P-gp) expression and intracellular DNR concentration were detected by flow cytometry. The results showed that the IC(50) of DNR on K562/A02 and K562 cells were 23.51 mg/L and 0.29 mg/L, respectively. The IC(50) of DNR on K562/A02 cells in treatment with raloxifene CsA and both combination were 5.98, 8.15 and 3.68 mg/L respectively, but both drugs not influenced IC(50) of DNR on K562 cells. Pretreating K562/A02 cells with raloxifene (2.5 mg/L) or CsA (1 mg/L) for 48 hours partially restored the sensitivity of K562/A02 cells to DNR. Cyclosporine A and raloxifene (alone or combination) elevated the intracellular DNR concentration in K562/A02, down regulated P-gp and mdr-1 mRNA expressions. It is concluded that multidrug resistance (MDR) can be partially reversed by CsA or raloxifene, the combination of both drugs shows a great synergistic reversal effect.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

[Effects of hydraulic retention time (HRT) on nitrification performance and microbial community of conventional activated sludge (CAS)].

A conventional activated sludge system was used to treat the ammonium-bearing inorganic wastewater for 260 days under decreased HRTs. When treating 500 mg x L(-1) NH4+ -N wastewater, over 98% ammonia removal could be obtained at HRT > or =20 h. Sharp washout of biomass occurred when HRT was further decreased, resulting in the accumulation of ammonium and nitrite. Changes in the community structure were monitored by microbial quinone and conventional analytical methods. Quinone profiles indicated that ammonia-oxidizing bacteria (AOB) in beta-Protevbacteria and Nitrobacteria in alpha-Proteobacteria were the predominant species to oxidize ammonia and nitrite, respectively. The number of AOB decreased with the reduction of biomass in bioreactor, while that of nitrite-oxidizing bacteria (NOB) changed little and fluctuated at 10(5) CFU x L(-1)

Biodiversity↗
PubMed2006

[Clinicopathologic study of ischemic intestinal disease due to mesenteric venous lesions].

OBJECTIVE: To study the clinical and pathologic features of ischemic intestinal disease due to mesenteric phlebitis. METHOD: The clinical and pathologic features of the mesenteric venous lesions in 3 patients of ischemic intestinal disease admitted during the period from 2003 to 2004 were studied. RESULTS: All 3 patients had a clinical history of acute abdominal pain accompanying with a diffuse peritonitis. During operation, an infarcted intestinal segment was identified and was resected respectively in each patient. Histologic examination showed a lymphocytic infiltration and fibrinoid necrosis of the small to medium-sized veins, associated with mural thrombosis and infarction of the corresponding intestinal wall and mesentery. The mesenteric arteries were spared. Two-year follow up of one case showed no evidence of local recurrence or systemic vasculitis. CONCLUSIONS: Ischemic intestinal disease due to mesenteric phlebitis is a rare entity with a pathological feature of inflammation of venous wall accompanying with the development of mural thrombosis and subsequent haemorrhagic infarction of intestine. The etiology is unknown and surgical resection of the involved intestinal segment is usually recommended.

Adult↗
PubMed2005

X-ray crystallographic characterization of rhesus macaque MHC Mamu-A*02 complexed with an immunodominant SIV-Gag nonapeptide.

Simian immunodeficiency virus (SIV) in the rhesus macaque is regarded as a classic animal model, playing a crucial role in HIV vaccine strategies and therapeutics by characterizing various cytotoxic T-lymphocyte (CTL) responses in macaque monkeys. However, the availability of well documented structural reports focusing on rhesus macaque major histocompatibility complex class I (MHC I) molecules remains extremely limited. Here, a complex of the rhesus macaque MHC I molecule (Mamu-A*02) with human beta2m and an immunodominant SIV-Gag nonapeptide, GESNLKSLY (GY9), has been crystallized. The crystal diffracts X-rays to 2.7 A resolution and belongs to space group C2, with unit-cell parameters a = 124.11, b = 110.45, c = 100.06 A, and contains two molecules in the asymmetric unit. The availability of the structure, which is being solved by molecular replacement, will provide new insights into rhesus macaque MHC I (Mamu-A*02) presenting pathogenic SIV peptides.

Animals↗
PubMed2005

[Anatomical study about the posterior coaxial portals via posterior tibial tendon sheath for ankle arthroscopy].

OBJECTIVE: To conduct the anatomical study about the posterior coaxial portals via posterior tibial tendon (PTT) sheath for ankle arthroscopy. METHODS: Coaxial portals were established in 20 ankles by K-wires which were left in place for distance measurement between them and the posterior nerves, tendons and vessels. Ankle arthroscopy was performed in 5 fresh ankles using 2.7 mm 300 arthroscopy with the same portals as mentioned above. The maximum visible scope were recorded and the distance between the arthroscopy and the posterior nerves, tendons and vessels was also measured. RESULTS: The medial portal was located 5 - 12 mm (average, 8 mm) above the tip of medial malleolus, and the lateral portal was located 8 - 24 mm (average, 15 mm) above the tip of lateral malleolus. The coaxial portals, which traversed the PTT sheath and passed posterior to the fibular, not only separated the arthroscopy and instrument from the posterior nerves, tendons and vessels by posterior capsule but also enlarged their distance. The medial and lateral malleolus articular gap, the posterior capsule could be viewed by these portals with as much as 1/2 - 2/3 posterior articular surface of talus. Not only the tibiotalar articular gap but also the dynamic movement between the mortise and the talus were clearly observed. Arthroscopic operation could be performed by instrument through the posterolateral portal. CONCLUSIONS: The posterior coaxial portals via PTT sheath for ankle arthroscopy have such advantages as easy maneuverability, superior safety, clear vision and larger operation field under arthroscopy.

Ankle Joint↗
PubMed2005

Preoperative lymph node staging of early-stage cervical carcinoma by [18F]-fluoro-2-deoxy-D-glucose-positron emission tomography.

BACKGROUND: Increasing evidence has documented the value of positron emission tomography (PET) in oncology, but only limited data are available comparing PET findings with the pathologic status of regional lymph nodes in patients with cervical carcinoma. The objective of this study was to determine the sensitivity and specificity of PET in detecting lymph node metastasis in women with early-stage cervical carcinoma. METHODS: The authors performed a retrospective review of all patients with Stage IA-IIA cervical carcinoma who underwent PET before surgery from 1999 to 2004. The status of the regional lymph nodes was correlated with lymph node pathology. RESULTS: Fifty-nine patients were identified. Pelvic lymph node metastases were present in 32% of the patients and were detected by PET with a sensitivity of 53%, a specificity of 90%, a positive predictive value (PPV) of 71%, and a negative predictive value (NPV) of 80%. Paraaortic lymph node disease was present in 9% of patients and was detected by PET with a sensitivity of 25%, a specificity 98%, a PPV of 50%, and an NPV of 93%. The mean size of the tumor deposits was larger in the PET-positive pelvic nodes (15.2 mm; range, 2-35 mm) than in the PET-negative lymph nodes (7.3 mm; range, 0.3-20 mm; P = 0.002). Computed tomography (CT) scans were obtained before surgery in 42 patients. The combined sensitivity of PET and CT in these patients was 75%. PET alone detected 9 (36%) of the positive lymph node groups, whereas CT alone detected 3 (12%) of the positive lymph node groups. Neither PET nor CT detected the positive lymph node groups in 8 patients (32%). CONCLUSIONS: Pathologic validation of PET imaging demonstrated a low sensitivity and a high specificity for PET in patients with early-stage cervical carcinoma.

Female↗
PubMed2005

Ab initio configuration-interaction study of the ground and low-lying electronic states of NiI.

For the first time, we have studied the potential-energy curves, spectroscopic terms, vibrational levels, and the spectroscopic constants of the ground and low-lying excited states of NiI by employing the complete active space self-consistent-field method with relativistic effective core potentials followed by multireference configuration-interaction calculations. We have identified six low-lying electronic states of NiI with doublet spin multiplicities, including three states of Delta symmetry and three states of Pi symmetry of the molecule within 15 000 cm(-1). The lowest (2)Delta state is identified as the ground state of NiI, and the lowest (2)Pi state is found at 2174.56 cm(-1) above it. These results fully support the previous conclusion of the observed spectra although our computational energy separation of the two states is obviously larger than that of the experimental values. The present calculations show that the low-lying excited states [13.9] (2)Pi and [14.6] (2)Delta are 3 (2)Pi and 3 (2)Delta electronic states of NiI, respectively. Our computed spectroscopic terms, vibrational levels, and spectroscopic constants for them are in good agreement with the experimental data available at present. In the present work we have not only suggested assignments for the observed states but also computed more electronic states that are yet to be observed experimentally.

Journal Article↗
PubMed2005

The rice dwarf virus P2 protein interacts with ent-kaurene oxidases in vivo, leading to reduced biosynthesis of gibberellins and rice dwarf symptoms.

The mechanisms of viral diseases are a major focus of biology. Despite intensive investigations, how a plant virus interacts with host factors to cause diseases remains poorly understood. The Rice dwarf virus (RDV), a member of the genus Phytoreovirus, causes dwarfed growth phenotypes in infected rice (Oryza sativa) plants. The outer capsid protein P2 is essential during RDV infection of insects and thus influences transmission of RDV by the insect vector. However, its role during RDV infection within the rice host is unknown. By yeast two-hybrid and coimmunoprecipitation assays, we report that P2 of RDV interacts with ent-kaurene oxidases, which play a key role in the biosynthesis of plant growth hormones gibberellins, in infected plants. Furthermore, the expression of ent-kaurene oxidases was reduced in the infected plants. The level of endogenous GA1 (a major active gibberellin in rice vegetative tissues) in the RDV-infected plants was lower than that in healthy plants. Exogenous application of GA3 to RDV-infected rice plants restored the normal growth phenotypes. These results provide evidence that the P2 protein of RDV interferes with the function of a cellular factor, through direct physical interactions, that is important for the biosynthesis of a growth hormone leading to symptom expression. In addition, the interaction between P2 and rice ent-kaurene oxidase-like proteins may decrease phytoalexin biosynthesis and make plants more competent for virus replication. Moreover, P2 may provide a novel tool to investigate the regulation of GA metabolism for plant growth and development.

Amino Acid Sequence↗
PubMed2005

Genetic alterations and expression of inhibitor of growth 1 in human sporadic colorectal cancer.

AIM: To explore the effect and significance of inhibitor of growth 1 (ING1) gene in carcinogenesis and progression of human sporadic colorectal cancer. METHODS: mRNA expression, mutation, and loss of heterozygosity (LOH) of ING1 gene in 35 specimens of sporadic colorectal cancer tissues and the matched normal mucous membrane tissues were detected by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), PCR-single strain conformation polymorphism (PCR-SSCP) and PCR-simple sequence length polymorphism (PCR-SSLP) using microsatellite markers, respectively. RESULTS: The average ratios of light intensities of p33(ING1b) and p47(ING1a) mRNA expression in the cancerous tissues were significantly lower than those in normal tissues. The difference between the two mRNA splices was not significant in the matched tissues. In addition, the ratios of light intensities of p33(ING1b) and p47(ING1a) mRNA expression in the cancerous tissues of Dukes' stages C and D were significantly lower than those in cancerous tissues of Dukes' stages A and B. However, no mutation of ING1 gene was detected in all 35 cases; only 4 cases of LOH (11.4%) were found. CONCLUSION: p33(ING1b) and p47(ING1a) mRNA expressions are closely related with the carcinogenesis and progression of human sporadic colorectal cancer. No mutation of ING1 gene is found, and there are only few LOH in sporadic colorectal cancers. These might not be the main reasons for the down regulation of ING1 expression. Its low expression may happen in transcription or post-transcription.

Colorectal Neoplasms↗
PubMed2005

Study on interaction between poly(amidoamine) dendrimer and CdSe nanocrystal in chloroform.

The binding of different categories of molecules to quantum dot has been studied for many years through different spectroscopic techniques to elucidate details of binding mechanism. In this work we present the results of the study of the interactions between CdSe and poly(amidoamine) dendrimer monitored by photoluminescence spectroscopy of CdSe in chloroform. Dendrimers with different terminal groups and different generations were used to bind with CdSe nanocrystal of different size. Significant differences in the values of binding constant Kb(n) and K(SV) were found in these experiments. The binding constant for poly(amidoamine) dendrimer of generation 4.0 is higher as compared to generation 3.5. The interaction of CdSe with poly(amidoamine) dendrimer shows an increase of binding constants with increasing dendrimer generation from 2.0 to 4.0, as well as with decreasing CdSe diameter. From HRTEM and FTIR analysis, we suggest that dendrimer/CdSe interactions are primarily hydrogen-bonding.

Cadmium Compounds↗
PubMed2005

Segmentation algorithm for DNA sequences.

A new measure, to quantify the difference between two probability distributions, called the quadratic divergence, has been proposed. Based on the quadratic divergence, a new segmentation algorithm to partition a given genome or DNA sequence into compositionally distinct domains is put forward. The new algorithm has been applied to segment the 24 human chromosome sequences, and the boundaries of isochores for each chromosome were obtained. Compared with the results obtained by using the entropic segmentation algorithm based on the Jensen-Shannon divergence, both algorithms resulted in all identical coordinates of segmentation points. An explanation of the equivalence of the two segmentation algorithms is presented. The new algorithm has a number of advantages. Particularly, it is much simpler and faster than the entropy-based method. Therefore, the new algorithm is more suitable for analyzing long genome sequences, such as human and other newly sequenced eukaryotic genome sequences.

Algorithms↗
PubMed2005

[Analgesic effect of intrathecal transplant of immortalized rat astrocyte strain genetically modified by human preproenkephalin gene on rat chronic neuropathic pain].

OBJECTIVE: To observe the analgesic effect of intrathecal transplant of immortalized rat astrocyte genetically modified by human preproenkephalin gene (IAST/hPPE) on chronic neuropathic pain. METHODS: 40 adult male Sprague-Dawley rats were randomly divided into four groups, 10 rats for each group. Naive group, SNI group, SNI + IAST group and SNI + IAST/hPPE group. The immortalized rat astrocyte (IAST) or IAST/hPPE co-incubated with bromodeoxyuridine (BrdU) in vitro were transplanted in the lumbar 4 to 6 subarachnoid space near the spinal cord 1 week after right side spared nerve injury (SNI). All animals were tested for bilateral 50% hindpaw withdrawal threshold (PWT) to a graded series of Von Frey hairs stimulation once a week from one week before SNI to six weeks after transplant, the difference value for right 50% PWT minus left 50% PWT was calculated and the effect of intraperitoneal naloxone on the analgesic efficacies was also observed. The content of L-EK in the spinal cord of L4 - 6 and was determined using immunohistochemistry and radioimmunoassay, and the expression of BrdU in grafts was determined using immunohistochemistry. RESULTS: Allodynia-like behaviour after 1 week following SNI was observed. As compared with Naive group, the difference value for the right 50% PWT minus left 50% PWT in the other three groups was higher significantly (P < 0.01). The tactile allodynia induced by SNI was significantly alleviated during the 1 to 6 week period after transplantation of IAST/hPPE cells, but transplants of IAST cells had no effect on the allodynia-like behaviour. The difference value for the right 50% PWT minus left 50% PWT in SNI + IAST/hPPE group was lower significantly than that in the SNI and SNI +I AST group (P < 0.01), but there was no significant difference between SNI and SNI + IAST group (P > 0.05). The efficacies were reversed by intraperitoneal naloxone in SNI + IAST/hPPE group. The content of L-EK in the lumbar spinal cord in IAST/hPPE group (108.1 pg/mg +/- 12.5 pg/mg) was significantly higher than that in other three groups (P < 0.01), but there was no significant difference between SNI and SNI + IAST group (25.4 pg/mg +/- 1.9 pg/mg vs 28.0 pg/mg +/- 2.1 pg/mg, P > 0.05). Furthermore, The grafts in the surface of dorsal horn were still stained positively for BrdU, they survived greater than 6 weeks on the pia mater around the spinal cord. CONCLUSION: Intrathecal transplant of IAST/hPPE cells could alleviate the allodynia-like behaviour after chronic neuropathic pain, which is associated with enkephalin secreted continuously from the grafts and conducted via opiate receptors.

Animals↗
PubMed2005

Biochemical and biophysical characterization of the transmissible gastroenteritis coronavirus fusion core.

Transmissible gastroenteritis coronavirus (TGEV) is one of the most destructive agents, responsible for the enteric infections that are lethal for suckling piglets, causing enormous economic loss to the porcine fostering industry every year. Although it has been known that TGEV spiker protein is essential for the viral entry for many years, the detail knowledge of the TGEV fusion protein core is still very limited. Here, we report that TGEV fusion core (HR1-SGGRGG-HR2), in vitro expressed in GST prokaryotic expression system, shares the typical properties of the trimer of coiled-coil heterodimer (six alpha-helix bundle), which has been confirmed by a combined series of biochemical and biophysical evidences including size exclusion chromatography (gel-filtration), chemical crossing, and circular diagram. The 3D homologous structure model presents its most likely structure, extremely similar to those of the coronaviruses documented. Taken together, TGEV spiker protein belongs to the class I fusion protein, characterized by the existence of two heptad-repeat (HR) regions, HR1 and HR2, and the present knowledge about the truncated TGEV fusion protein core may facilitate in the design of the small molecule or polypeptide drugs targeting the membrane fusion between TGEV and its host.

Amino Acid Sequence↗
PubMed2005

Combination of tetrandrine as a potential-reversing agent with daunorubicin, etoposide and cytarabine for the treatment of refractory and relapsed acute myelogenous leukemia.

The potential mechanism of the chemotherapy resistance in acute myeloid leukemia (AML) is the multidrug resistance (MDR-1) gene product P-glycoprotein (P-gp), which is often overexpressed in myeloblasts from acute myeloid leukemia. In a multicenter clinical trial, 38 patients with poor risk forms of AML were treated with tetrandrine (TET), a potent inhibitor of the MDR-1 efflux pump, combined with daunorubicin (DNR), etoposide and cytarabine (TET-DEC). Overall, post-chemotherapy marrow hypoplasia was achieved in 36 patients. Sixteen patients (42%) achieved complete remission or restored chronic phase, 9 achieved partial remission (PR) and 13 failed therapy. Toxicities included infection, myelosuppression, stomatitis, mucositis, cerebellar toxicity and reversible cardiotoxicity. There was no significant difference in response for P-gp-positive and -negative patients. P-gp function was assessed in 26 patients by flow cytometric analysis, TET-contained plasma-augmented DNR accumulation relative to pretreatment plasma in K562/A02 cells by a median value of 88+/-101% (range, 11-501%). However, there was no difference in DNR uptake between responding and non-responding patients. Our data showed that TET-DEC was relatively well tolerated in these patients with poor risk AML, and had encouraging antileukemic effects.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Vasculoprotective effect of insulin in the ischemic/reperfused canine heart: role of Akt-stimulated NO production.

OBJECTIVES: The objectives of this study were to investigate the vasculoprotective effects of glucose-insulin-potassium (GIK) on ischemia/reperfusion-induced coronary endothelial functional injury and to elucidate the mechanism involved. METHODS: Dogs were subjected to 50 min of coronary occlusion and 4 h of reperfusion. Vehicle, GIK, or GK were intravenously infused 5 min before reperfusion, and the coronary vascular dysfunction and endothelial apoptosis were determined. In a separate study, cultured endothelial cells were subjected to simulated ischemia/reperfusion, and the signaling pathway involved in insulin's anti-apoptotic effect was investigated. RESULTS: In vivo ischemia/reperfusion caused significant coronary vascular endothelial dysfunction as evidenced by reduced endothelium-dependent vasorelaxation, decreased nitric oxide (NO) production, and endothelial cell apoptosis as determined by caspase 3 activation and TUNEL staining. Treatment with GIK, but not GK, markedly improved the endothelium-dependent coronary vasorelaxation (P<0.01 versus vehicle), increased total NO production (P<0.01), and attenuated endothelial apoptosis. In cultured endothelial cells, treatment with insulin also markedly increased NO production and reduced simulated ischemia/reperfusion-induced apoptosis. Moreover, pre-treatment with either Akt inhibitor or NO synthase inhibitor almost abolished the anti-apoptotic effect exerted by insulin but not by SNAP, an NO donor. CONCLUSION: These results demonstrate that in vivo treatment with GIK at reperfusion attenuates ischemia/reperfusion-induced coronary endothelial dysfunction and endothelial apoptosis in an Akt-dependent and NO-mediated fashion. The coronary vasculoprotective effect elicited by insulin may contribute to the previously observed cardiac protective effect of GIK.

Acetylcholine↗