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Biomedical subjects

G Lu

Publications and source records attributed to G Lu.

At least 73 records · Page 4Linked to original sources
PubMed1999

Inflammatory modulation of calcium-activated potassium channels in canine colonic circular smooth muscle cells.

BACKGROUND & AIMS: The characteristics of colonic circular smooth muscle slow waves are altered during inflammation. The aim of this study was to examine whether inflammation modulates the open-state probability of Ca2+-activated K+ (KCa) channels in these cells to contribute to these alterations. METHODS: The experiments were performed on freshly dissociated single smooth muscle cells from the canine colon using standard patch clamp methods. Inflammation was induced by mucosal exposure to ethanol and acetic acid. RESULTS: Inflammation decreased the open-state probability of large-conductance KCa (BK) channels in the cell-attached and excised inside-out configurations. The voltage sensitivity of the channels was also reduced during inflammation. Inflammation had no significant effect on the large, medium, and small conductances or the unitary current levels of channel openings. However, it decreased the maximum number of simultaneous channel openings. The channels were Ca2+-dependent and were blocked by tetraethylammonium and charybdotoxin in normal and inflamed cells. CONCLUSIONS: Inflammation decreases the open-state probability of BK channels. This may partially reverse the decrease in duration and amplitude of slow waves and depolarization of membrane potential seen in inflammation.

Animals↗
PubMed1999

Omega-3 fatty acids alter lipoprotein subfraction distributions and the in vitro conversion of very low density lipoproteins to low density lipoproteins.

The purpose of this study was to determine the effects of a fish oil concentrate (FOC) on the in vitro conversion of very low density lipoproteins (VLDL) to intermediate (IDL) and low density lipoproteins (LDL). Six hypertriglyceridemic patients were randomly allocated to receive either placebo (olive oil) or FOC (1 g/14 kg body weight/day) for 4 weeks in a crossover study with a 4-week washout period. The FOC provided 3 g of eicosapentaenoic + docosahexaenoic acid per 70 kg of body weight, and it lowered plasma triglyceride and VLDL cholesterol levels by 35% and 42%, respectively. Decreases in the largest particles (VLDL(1)) were primarily responsible, with no effect noted in smaller VLDL particles (VLDL(2) and VLDL(3)). The FOC increased LDL cholesterol levels by 25% (P < 0.06) but did not affect LDL particle size. VLDL(1) and VLDL(3) were incubated in vitro with human postheparin lipases. Although triglycerides from both types of VLDL were hydrolyzed to the same extent with both treatments, particles isolated during the FOC phase were more readily converted into IDL and LDL than were control particles. These data suggest that the marine omega3 fatty acids may enhance the propensity of VLDL to be converted to LDL, partly explaining the decreased VLDL and increased LDL levels in FOC-treated patients.

Clinical Trial↗
PubMed1999

A study of fluctuating asymmetry in hybrids of dwarf and normal lake whitefish ecotypes (Coregonus clupeaformis) from different glacial races.

Fish ecotypes found in north temperate lakes are increasingly used as model organisms to explore patterns and processes of population divergence that may ultimately cause speciation. Processes involved in their reproductive isolation are, however, still poorly understood. Recent experimental studies on whitefish ecotypes from different glacial races revealed that embryonic mortality of hybrids was 2.4-4.7 times higher than for parental forms. In this study, we compared fluctuating asymmetry (FA) in morphological traits of these same hybrid and pure crosses to test the hypothesis that genetic stress observed in hybrids at embryonic stages is also manifested at later developmental stages. Twelve morphological traits were used to measure asymmetry. Variable degrees of asymmetry were observed depending on traits and crosses, however there was no significant difference in FA among crosses. These results thus provided no evidence in support of the working hypothesis and indicated that genetic stress may differ among life stages. It is more likely that high hybrid embryonic mortality acts together with ecological factors at later stages to increase further the extent of reproductive isolation between sympatric whitefish ecotypes.

Animals↗
PubMed1999

Upregulation of vascular endothelial growth factor is associated with radiation-induced blood-spinal cord barrier breakdown.

The pathogenesis of radiation-induced injury to the central nervous system (CNS) remains unclear. Dysfunction of the blood-brain barrier (BBB) is associated with radiation-induced white matter lesions. The aim of this study was to determine if vascular endothelial growth factor (VEGF) is implicated in radiation-induced BBB disruption. Adult rats were irradiated with a single dose of 8 or 22 Gy to the spinal cord from C2 to T2. At various times up to 20 weeks following irradiation, blood-spinal cord barrier (BSCB) permeability was assessed using immunohistochemistry with anti-albumin antibody. Cell proliferation was assessed using bromodeoxyuridine (BrdU), and endothelial cell identity was assessed morphologically and using immunostaining for factor VIII-related antigen. Expression of VEGF protein and message was assessed using immunohistochemistry and in situ hybridization respectively. In the unirradiated rat spinal cord, there was no evidence of albumin immunoreactivity and little evidence of VEGF expression. After a dose of 22 Gy, focal albumin staining in white matter was observed at 16 weeks. Diffuse staining was seen at 20 weeks and was associated with necrosis and demyelination in white matter. This was associated with a significant increase in white matter glial cells that showed immunoreactivity and in situ hybridization signal for VEGE VEGF expressing cells showed dual immunoreactivity for glial fibrillary acidic protein. No increase in VEGF positive cells was observed in gray matter after 22 Gy. After a dose of 8 Gy, there was no increase in VEGF expression or albumin immunostaining in either white or gray matter. Microvessel endothelial cell density showed a trend towards a decrease with time after 22 Gy as compared with 8 Gy or unirradiated controls. BrdU immunostaining provided no evidence for endothelial cell proliferation in control or in the irradiated spinal cord. It is concluded that radiation-induced BSCB dysfunction is associated with upregulation of VEGF in astrocytes without associated endothelial proliferation. The temporal and spatial association of VEGF upregulation with the white matter lesions suggests a role of VEGF in radiation-induced late CNS injury.

Animals↗
PubMed1999

[Sex determination of human preimplantation embryo blastomere using dualcolor fluorescence in situ hybridization].

OBJECTIVE: To establish a series of techniques of sex determination of human preimplantation embryo in order that preimplantation genetic diagnosis(PGD) can be used clinically. METHODS: Use micromanipulation for biopsy of human preimplantation embryo(3-10 cell) and prepare single-cell interphase nuclei sample. Make sex determination of human preimplantation embryos by using dual-color fluorescence in situ hybridization. RESULTS: The technique of human preimplantation embryo (3-10 cell) biopsy was established preliminarily and the technique of preparing single-cell interphase nuclei sample was set up and stabilized. The sex determination of the blastomere of human preimplantation embryo was successful. CONCLUSION: This series of techniques can make fast diagnosis (less than 6 hours) with minimal sample(only one cell), with no cell culture, and with high accuracy of sex determination (100%).

Blastocyst↗
PubMed1999

Cellular DNA, ras p21 and p53 expression in the carcinogenesis of adenomatous colorectal polyps.

OBJECTIVE: To explore the possible roles of cellular DNA, oncogene ras and tumor suppressor gene p53 in the carcinogenesis of colorectal adenomatous polyps (CAP). STUDY DESIGN: Cellular DNA content, oncogene ras and tumor suppressor gene p53 expression at the protein level were quantitatively studied with flow cytometry (FCM) in 16 cases of CAP with mild epithelial dysplasia (CAP-MD), 16 cases of CAP with moderate/severe epithelial dysplasia (CAP-M/SD) and 11 cases of cancer in adenomatous polyps (CIAP). RESULTS: Nuclear DNA contents of CAP-M/SD (DNA [DI] = 1.11 +/- 0.06) and CIAP (DI = 1.29 +/- 0.03) were significantly higher than those of CAP-MD (DI = 1.06 +/- 0.06) and normal controls (DI = 1.00, P < .005) and were in the FCM DNA aneuploidy range. The rates and amount (as determined by the fluoresence index) of mutant p53 protein expression in CAP-M/SD and CIAP were significantly higher than those in the control and CAP-MD groups. Positive rates of ras p21 expression were all high in CAP-MD, CAP-M/SD and CIAP (80%, 75% and 100%, respectively), yet the intensity of expression in the last was significantly stronger than those in the former two groups. DNA aneuploid, ras p21 and p53 coexpression were found in 10 of 11 cases of CIAP. CONCLUSION: The results suggest that cellular DNA, ras p21 and p53 are all involved in the carcinogenesis of CAP. Clinically, the appearance of DNA aneuploidy, ras p21 or p53 overexpression should be considered markers of malignant conversion in CAP.

Adenomatous Polyps↗
PubMed1999

[Construction and expression of HLA-DRalpha, DRB1*0401 transgenic mice model].

OBJECTIVE: To construct transgenic mice model on DR alpha and DRB1*0401 of human MHC-II molecules. METHODS: By microinjection techniques on germ nucleus of zygotes, DRalpha and DRB1*0401 genes were injected into zygotes of C57BL/6 x DBA/1 hybrid mice and transplanted into the oviducts of pseudopregnancy female mice. The integration and expression of exogenous genes in offspring were detected by PCR, Southern blot and Northern blot, RT-PCR analysis. RESULTS: There were 5 founders of all injected mice, which had steadily inherited to the fifth generation. It was found that 95 mice were positive by PCR and 68 mice were integrated exogenous gene by Southern blot analysis. DRalpha and DRB1*0401 genes were expressed on spleen and kidney of transgenic mice. CONCLUSION: This experiment on the construction of DRalpha and DRB1*0401 transgenic mice model is a success.

Animals↗
PubMed1999

[Analysis on epidemiological feature of injuries in civic students of Jiangmen].

OBJECTIVE: In order to set up intervention measures in preventing injuries. METHODS: An analysis on the epidemiological feature of injuries in 9 civic middle and primary schools with 3,988 students involved was carried out in July 1998. RESULTS: The results showed that the total rate of 12 kinds of injuries was 50.55%. Among which, 5 kinds of injuries took the first 5 places: injuries from falls (32.15%), knife-cutting or sharp weapon hurt (21.99%) bumps (17.05%) traffic accidents (12.51%) burns and scalds (11.43%). CONCLUSION: The rate of injury was related closely with age parent's culture background and the number of children in families, but was not significantly related to sex, parent's occupation and the condition of living with relatives. Strengthening supervision, safety health education and increase awareness on self-protection were the most important points. Some intervention measures were being put into practice.

Adolescent↗
PubMed1999

Expression of yellow jacket and wasp venom Ag5 allergens in bacteria and in yeast.

Antigen 5 (Ag5), of unknown biological function, is one of the major venom allergens of vespids and fire ants. We have compared the expression of Ag5 in bacteria and in yeast. Recombinant Ag5 from bacteria formed an insoluble intracellular product, which was not properly folded, but that produced in Pichia pastoris was secreted to the extracellular medium. Immunochemical characterizations showed the secreted Ag5 to have the native structure of the natural protein. This is of interest since the B cell epitopes of Ag5 are mainly of the discontinuous type. These studies were made with Ag5s from yellow jacket (Vespula vulgaris) and paper wasp (Polistes annularis), and with hybrid Ag5 molecules that contained partial sequences of these two species. In vitro allergenicity studies with sera from yellow jacket-sensitive patients showed that some of these hybrid molecules had a greatly reduced allergenicity but retained the immunogenicity of the natural allergen. This could be of importance for immunotherapy of this type of allergy.

Allergens↗
PubMed1999

[Gene detection and localization by FISH with short DNA fragment cloned in plasmid].

OBJECTIVE: To establish a method of detecting and localizing newly cloned gene by FISH using short DNA fragment. METHODS: Bio-14-dATP was incorporated into the target gene cloned in plasmid by nick translation followed by conventional FISH with some modification. By Means of this method, c-met, c-erbB2, 1A6, APC and Rb genes were examined in ovarian and gastric cancer cell lines. RESULTS: 1A6, a newly isolated gene was located at the long arm of one of the C group chromosomes. Oncogene c-met, c-erbB2 and trmor suppressor gene APC, Rb were shown to produce clear-cut hybridization signals in ovarian and gastric cancer cells. CONCLUSION: Short DNA fragment cloned in plasmid is useful for studies of gene localization, gene deletion and amplification by FISH.

Chromosome Mapping↗
PubMed1999

[Early use of Chinese drug rhodiola compound for patients with post-trauma and inflammation in prevention of ALI/ARDS].

OBJECTIVE: To evaluate the effects of the Chinese drug rhodiola on the preventive treatment of acute lung injury (ALI) caused by post-traumatic/inflammatory and thoracic-cardiovascular operations. METHODS: 104 patients who coincide with their diagnosis and standard scale were divided randomly in to single number groups A(1), B(1), C(1) and D(1) (early preventive treatment group EG) and double number groups A(2), B(2), C(2) and D(2) (control group CG). The treatment of primary disease both in EG and CG was similar, but in EG four grams of rhodiola compound (RCO) were used every day for a period of 3-15 days since admission and 5-7 days after operation. The indicators related to ALI in each groups were measured. RESULTS: PaO(2), AaDO(2) and hemorheology were significant in EG than in CG (P < 0.05) or (P < 0.01). The complication rate of ARDS was decreased about of 50.0% in EG than in CG. CONCLUSIONS: Early use of RCO may protect against major risk factors of ALI/ARDS caused by massive trauma/infection and thoracic-cardio-operations.

Adolescent↗
PubMed1999

[Posttraumatic or inflammatory acute respiratory distress syndrome on high altitude area: a retrospective analysis of 94 deaths due to ARDS/MOF].

OBJECTIVE: To determine the characteristic predictors of acute respiratory distress syndrome (ARDS) in the high altitude area of China. METHODS: According to the diagnostic criteria of ARDS, 2 325 cases were screened in the recent 10 years. Except malignant tumors, cardio-cerebrovascular diseases, chronic obstructive pulmonary disease, and chronic multiple organ failure, the causes of death were analysed retrospectively. RESULTS: 94 cases (4.04%) were diagnosed as ARDS, but in the primary case record, only 27 cases (1.16%) had been diagnosed as ARDS/MOF. Of the 94 ARDS patients, 79 complicated by extrapulmonary organ damage involving the kidney, heart, liver, gastro-intestinal tract, and brain. A total of 305 organs were involved (average 3.24 organs each case). Lung failure only accounted for 15 cases. CONCLUSIONS: The combination of the diagnostic criteria of ARDS for high altitude area and flate area, injury severity scale, blood gas monitoring, and integrated traditional Chinese medicine and western medicine may improve the prognosis of ARDS.

Adolescent↗
PubMed1999

[Changes of erythrocyte membrane ATPase activities and plasma lipids in patients with coronary heart disease].

Fasting plasma triglyceride (TG), total cholesterol(TC), low density lipoprotein-cholesterol(LDL-C), high density lipoprotein-cholesterol(HDL-C), activities of erythrocyte membrane Na(+)-K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase, and intraerythrocytic calcium concentration were examined in 21 patients with coronary heart disease(CHD) and 21 normal controls. It was found that the plasma contents of TG, TC, LDL-C and intraerythrocytic [Ca2+] in patients with CHD were much higher while plasma contents of HDL-C, activities of erythrocyte membrane Na(+)-K(+)- and Ca(2+)-ATPase were much lower than those of normal controls. Mg(2+)-ATPase activity showed no significant difference between these two groups. The activities of erythrocyte membrane Na(+)-K(+)- and Ca(2+)-ATPase were negatively correlated with plasma TG, TC, LDL-C levels, respectively, and positively correlated with plasma HDL-C. The possible pathogenic mechanism is discussed on the basis of our results.

Adenosine Triphosphatases↗
PubMed1999

[Inhibitory effect of conjugated linoleic acid on human gastric carcinoma cell line].

The effects of conjugated linoleic acid (CLA) on human gastric carcinoma cell line (SGC-7901) were studied in cell culture. The four levels of CLA in medium were designed as 25, 50, 100 and 200 mumol/L, and the dissolvent control being ethane. The result displayed that CLA could inhibit the cell proliferation, cellular mitosis, cell clone formation and DNA synthesis and induce cellular differentiation of SGC-7901 cells.

Adenocarcinoma↗
PubMed1999

[The novel copolymer coated capillary columns of electrophoresis and their applications to separation of proteins].

The copolymer of acrylonitrile, methyl acrylate, hydroxy ethyl acrylate (ZB-004), the copolymer of acrylonitrile, methyl acrylate, hydroxy ethyl acrylate, acrylamide (ZB-014) and the copolymer of acrylonitrile, hydroxy ethyl acrylate (ZB-016) were coated on the inner surface of fused-silica capillaries by just filling the capillary with solutions containing these copolymers followed by flushing the capillary with nitrogen. The physically adsorbed layer can reduce both protein adsorption and electroosmotic flow in the pH range of 3-5. Electroosmotic flow decreased by raising the concentrations of the copolymers. Separation performance of ZB-004 layer is better than those of other two layers due to its low hydrophilicity, but with higher pH values, appreciable peak deformation and increase in electroosmosis were observed. The intra day and inter day migration reproducibility were investigated in terms of relative standard deviation (RSD) with four basic proteins at pH 4.0. The RSDs of the intra day migration times were less than 2%. The RSDs of the inter day migration times were less than 4%. At pH 5.0, the RSDs of the migration times in two ZB-004-coated capillaries made on two different days were less than 1%. Separation efficiencies of four basic proteins in a ZB-004-coated capillary which stored in a buffer (pH 4.0) for fifteen days after being used for 14 days decreased 15%. These coatings were stable and exhibited reproducible separations from intra day, inter day and inter column under acidic conditions.

Acrylamide↗
PubMed1998

Reactivity studies of the tyrosyl radical in ribonucleotide reductase from Mycobacterium tuberculosis and Arabidopsis thaliana--comparison with Escherichia coli and mouse.

Ribonucleotide reductase (RNR) is a key enzyme for DNA synthesis since it provides cells with deoxyribonucleotides, the DNA precursors. Class I alpha2beta2 RNRs contain a dinuclear iron center and an essential tyrosyl radical in the beta2 component (protein R2). This is also true for the purified protein R2 of Mycobacterium tuberculosis RNR, as shown by iron analysis, light absorption and EPR spectroscopy. EPR spectroscopy at 286 GHz revealed a high g(x) value, suggesting that the radical is not hydrogen bonded, as in other prokaryotic R2s and in contrast with eukaryotic R2s (from Arabidopsis thaliana and mouse). Furthermore, it proved to be very resistant to scavenging by a variety of phenols and thiols and by hydroxyurea, similar to the Escherichia coli radical. By comparison, the plant and mouse radicals are very sensitive to drugs such as resveratrol and 2-thiophenthiol. The radical from M. tuberculosis RNR does not seem to be an appropriate target for new antituberculous agents.

Animals↗
PubMed1998

High resolution crystal structure of pyruvate decarboxylase from Zymomonas mobilis. Implications for substrate activation in pyruvate decarboxylases.

The crystal structure of tetrameric pyruvate decarboxylase from Zymomonas mobilis has been determined at 1.9 A resolution and refined to a crystallographic R-factor of 16.2% and Rfree of 19.7%. The subunit consists of three domains, all of the alpha/beta type. Two of the subunits form a tight dimer with an extensive interface area. The thiamin diphosphate binding site is located at the subunit-subunit interface, and the cofactor, bound in the V conformation, interacts with residues from the N-terminal domain of one subunit and the C-terminal domain of the second subunit. The 2-fold symmetry generates the second thiamin diphosphate binding site in the dimer. Two of the dimers form a tightly packed tetramer with pseudo 222 symmetry. The interface area between the dimers is much larger in pyruvate decarboxylase from Z. mobilis than in the yeast enzyme, and structural differences in these parts result in a completely different packing of the subunits in the two enzymes. In contrast to other pyruvate decarboxylases, the enzyme from Z. mobilis is not subject to allosteric activation by the substrate. The tight packing of the dimers in the tetramer prevents large rearrangements in the quaternary structure as seen in the yeast enzyme and locks the enzyme in an activated conformation. The architecture of the cofactor binding site and the active site is similar in the two enzymes. However, the x-ray analysis reveals subtle but significant structural differences in the active site that might be responsible for variations in the biochemical properties in these enzymes.

Amino Acid Sequence↗