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Hong Gao

Publications and source records attributed to Hong Gao.

At least 55 records · Page 3Linked to original sources
PubMed2005

Glutamate receptor 1-immunopositive neurons in the gliotic CA1 area of the mouse hippocampus after pilocarpine-induced status epilepticus.

Significant reduction in glutamate receptor 1 (GluR1)- and GluR2/3-immunopositive neurons was demonstrated in the hilus of the dentate gyrus in mice killed on days 1, 7 and 60 after pilocarpine-induced status epilepticus (PISE). In addition, GluR1 and GluR2/3 immunostaining in the strata oriens, radiatum and lacunosum moleculare of areas CA1-3 decreased drastically on days 7 and 60 after PISE. Neuronal loss observed in the above regions may account, at least in part, for a decrease in GluR immunoreactivity. By contrast, many GluR1-immunopositive neurons were observed in the gliotic area of CA1. Of these, about 42.8% were immunopositive for markers for hippocampal interneurons, namely calretinin (7.6%), calbindin (12.8%) and parvalbumin (22.4%). GluR1 or GluR2/3 and BrdU double-labelling showed that the GluR1- and GluR2/3-immunopositive neurons at 60 days after PISE were neurons that had survived rather than newly generated neurons. Furthermore, anterograde tracer and double-labelling studies performed on animals at 60 days after PISE indicated a projection from the hilus of the dentate gyrus to gliotic areas in both CA3 and CA1, where the projecting fibres apparently established connections with GluR1-immunopositive neurons. The projection to CA1 was unexpected. These novel findings suggest that the intrinsic hippocampal neuronal network is altered after PISE. We speculate that GluR1-immunopositive neurons in gliotic CA1 act as a bridge between dentate gyrus and subiculum contributing towards epileptogenesis.

Animals↗
PubMed2005

Recombinant modified vaccinia virus Ankara expressing the spike glycoprotein of severe acute respiratory syndrome coronavirus induces protective neutralizing antibodies primarily targeting the receptor binding region.

Immunization with a killed or inactivated viral vaccine provides significant protection in animals against challenge with certain corresponding pathogenic coronaviruses (CoVs). However, the promise of this approach in humans is hampered by serious concerns over the risk of leaking live severe acute respiratory syndrome (SARS) viruses. In this study, we generated a SARS vaccine candidate by using the live-attenuated modified vaccinia virus Ankara (MVA) as a vector. The full-length SARS-CoV envelope Spike (S) glycoprotein gene was introduced into the deletion III region of the MVA genome. The newly generated recombinant MVA, ADS-MVA, is replication incompetent in mammalian cells and highly immunogenic in terms of inducing potent neutralizing antibodies in mice, rabbits, and monkeys. After two intramuscular vaccinations with ADS-MVA alone, the 50% inhibitory concentration in serum was achieved with reciprocal sera dilutions of more than 1,000- to 10,000-fold in these animals. Using fragmented S genes as immunogens, we also mapped a neutralizing epitope in the region of N-terminal 400 to 600 amino acids of the S glycoprotein (S400-600), which overlaps with the angiotensin-converting enzyme 2 (ACE2) receptor-binding region (RBR; S318-510). Moreover, using a recombinant soluble RBR-Fc protein, we were able to absorb and remove the majority of the neutralizing antibodies despite observing that the full S protein tends to induce a broader spectrum of neutralizing activities in comparison with fragmented S proteins. Our data suggest that a major mechanism for neutralizing SARS-CoV likely occurs through blocking the interaction between virus and the cellular receptor ACE2. In addition, ADS-MVA induced potent immune responses which very likely protected Chinese rhesus monkeys from pathogenic SARS-CoV challenge.

Angiotensin-Converting Enzyme 2↗
PubMed2005

[Effects of carnitine acetyltransferase gene knockout on long chain dicarboxylic acid production and metabolism of Candida tropicalis].

Candida tropicalis can assimilate n-alkane as a sole carbon source and produce dicarboxylic acids (DCAs). The synthesis of DCAs is thought to be reduced by beta-oxidation. Carnitine acetyltransferase (CAT) is the major enzyme to transfer DCAs into beta-oxidative pathway, then DCAs would be catalyzed to generate ATP to supply cells with energy. A homologous recombination plasmid was constructed, in which CAT gene was disrupted by inserting hygromycin B resistance gene. This plasmid was used to transform Candida tropicalis wild type strain F10-1, and one single CAT gene knockout strain was obtained. Comparing with the wild type, the recombinant increased DCA13 yield and molar conversion of alkane by 13.0% and 11.8%, respectively, and decreased unnecessary consumption of DCAs in beta-oxidation.

Candida tropicalis↗
PubMed2005

[Expression and clinical significance of KISS-1 and GPR54 mRNA in endometrial carcinoma].

OBJECTIVE: To investigate the expression and clinical significance of KISS-1 mRNA and GPR54 mRNA in endometrial carcinoma. METHODS: The expression of KISS-1 mRNA and GPR54 mRNA in 32 patients with endometrial carcinoma, 10 patients with endometrial intraepithelial neoplasia (EIN) and 12 patients with normal endometrium was detected by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: The positive rate of KISS-1 mRNA in endometrial carcinoma, EIN and normal endometrium was 37.5%, 80.0% and 83.3% respectively (endometrial carcinoma vs EIN or normal endometrium, P < 0.05). The expression of KISS-1mRNA in patients with endometrial carcinoma was correlated with its clinical stage, myometrial invasion and lymph node metastasis (P < 0.05). In endometrial carcinoma, the more advanced clinical stage, the lower expression of KISS-1 mRNA was detected. The positive rate of GPR54 mRNA in endometrial carcinoma, EIN and normal endometrium was 78.1%, 70.0% and 66.7% respectively, with no significant statistical difference (P > 0.05). It was not correlated with the clinical stage, histology grade, myometrial invasion or lymph node metastasis (P > 0.05). CONCLUSION: The interaction of KISS-1 and GPR54 may play an important role in inhibiting the invasion and metastasis of endometrial carcinoma.

Adenocarcinoma↗
PubMed2005

[Expression of KAI1 gene in human laryngeal carcinoma and its clinical significance].

OBJECTIVE: To explore the mRNA expression of KAI1 gene in laryngeal squamous-cell carcinoma and its clinical significance. METHODS: Fresh laryngeal cancer samples taken from 40 laryngeal carcinoma cases and normal control laryngeal tissues from 9 subjects were examined with semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Moderate, low and negative expression rates of KAI1 gene mRNA in nine normal laryngeal tissues were 33.3% (3/9), 33.3% (3/9) and 33.3% (3/9), respectively. The high, moderate, low and negative expression rates of KAI1 mRNA in 25 laryngeal cancers without lymph node metastasis were 40.0% (10/25), 28.0% (7/25), 20.0% (5/25) and 12.0% (3/25), respectively. The moderate, low and negative expression rates of KAI1 mRNA in 15 laryngeal cancers with lymph node metastasis were 20.0% (3/15), 26.7% (4/15) and 53.3% (8/15), respectively. The KAI1 mRNA expression in the laryngeal cancers without lymph node metastasis was higher than that in normal laryngeal tissues (P < 0.05). The KAI1 mRNA expression in the laryngeal cancers with lymph node metastasis was lower than that in the laryngeal cancers without lymph node metastasis (P < 0.05). The high, moderate and low expression rates of KAI1 mRNA in 10 highly differentiated laryngeal cancers were 50.0% (5/10), 30.0% (3/10) and 20.0% (2/10), respectively. The high, moderate, low and negative expression rates of KAI1 mRNA in 12 low differentiation laryngeal cancers were 8.3% (1/12), 16.7% (2/12), 16.7% (2/12) and 58.3% (7/12), respectively. The differences of KAI1 mRNA expression between high and low differentiation laryngeal cancers were statistically significant (P < 0.05). CONCLUSION: The decrease of KAI1 mRNA expression may be related to lymph node metastasis and low differentiation of laryngeal squamous-cell carcinoma.

Adult↗
PubMed2005

[Relationship between changes of insulin like growth factor-1 and insulin like growth factor binding protein-1 in maternal serum and placenta and pathogenesis of hypertensive disorder complicating pregnancy].

OBJECTIVE: To investigate the role of insulin like growth factor-1 (IGF-1) and insulin like growth factor binding protein-1 (IGFBP-1) in the pathogenesis of hypertensive disorder complicating pregnancy. METHODS: The levels of IGF-1 and IGFBP-1 in serum and placenta were detected from 60 patients with hypertensive disorder complicating pregnancy (hypertensive disorder complicating pregnancy group) and 18 normal pregnant women (control group) by enzyme linked immunosorbent assay (ELISA) and immunohistochemistry. RESULTS: (1) Serum level of IGF-1 (229 +/- 100) microg/L in hypertensive disorder complicating pregnancy group was significantly lower than that in control group (336 +/- 120) microg/L, (P < 0.01). There were significant differences among gestational hypertension (303 +/- 80) microg/L, mild preeclampsia (233 +/- 77) microg/L and severe preeclampsia groups (155 +/- 73) microg/L, (P < 0.05). (2) The expression of IGF-1 in the placenta of hypertensive disorder complicating pregnancy group (48%, 29/60) was significantly reduced than that in control group (83%, 15/18; P < 0.01). Its expressions in mild and severe preeclampsia patients were lower than that in control group (P < 0.05, P < 0.01). (3) Serum IGFBP-1 from hypertensive disorder complicating pregnancy group (161 +/- 90) microg/L was significantly higher than that in control group (98 +/- 75) microg/L, (P < 0.01). There were significant differences among gestational hypertension (97 +/- 73) microg/L, mild preeclampsia (157 +/- 69) microg/L and severe preeclampsia groups (225 +/- 81) microg/L (P < 0.05). (4) The expression of IGFBP-1 in hypertensive disorder complicating pregnancy group (77%, 46/60) was higher than that in control group (39%, 5/18), (P < 0.01). Its expression in mild and severe preeclampsia patients were higher than that in control group (P < 0.05). (5) The levels of IGF-1 in serum and placenta had a significant negative relationship with that of IGFBP-1 in hypertensive disorder complicating pregnancy group (r = -0.269, P < 0.05; r = -0.369, P < 0.01). Levels of IGFBP-1 in maternal serum were positively related with that of placenta (P < 0.01). CONCLUSION: The changes of levels of IGF-1 and IGFBP-1 are related to the occurrence and development of hypertensive disorder complicating pregnancy.

Adult↗
PubMed2005

[Dynamics of soil active organic matter in Chinese fir plantations].

Soil active organic matter is the main source of soil nutrients, and plays an important role in the formation and stabilization of soil aggregate. Chinese fir (Cunninghamia lanceolata) is the most important fast-growing timber tree species in southern China, but its continuous plantation has caused soil deterioration. The study on the active fractions of soil organic matter under the first and second generation plantations of Chinese fir and the native broad-leaved forest at Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, in Hunan Province showed that their contents were higher under native broad-leaved forest than under Chinese fir plantations, and higher under the first than under the second generation plantation. The content of soil active organic carbon (SAOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC) and water-soluble carbohydrate (WSC) was 18.79 g x kg(-1), 421.7 mg x kg(-1), 252.2 mg x kg(-1) and 136.3 mg x kg(-1) under the first generation plantation of Chinese fir, and 22.31 g x kg(-1), 800.5 mg x kg(-1), 361.1 mg x kg(-1) and 220.1 mg x kg(-1) under the native broad-leaved forest, respectively. The corresponding values under the second generation plantation of Chinese fir were 73.6%, 87.9%, 66.3% and 53.2% of those under the first generation plantation of Chinese fir. The results also indicated that there existed some extent correlations among the active fractions of soil organic matter, and higher correlations between soil microbial biomass carbon and other active fractions of soil organic matter.

Carbon↗
PubMed2005

[Preventive and therapeutic effects of recombinant IFN-alpha2b nasal spray on SARS-CoV infection in Macaca mulata].

OBJECTIVE: To study the preventive and therapeutic effects of recombinant IFN-alpha2b for nasal spray on SARS-CoV infection in Macaca mulata (rhesus monkey). METHODS: Ten rhesus monkeys were divided into two groups, 5 in interferon group, and 5 in control group. Before and after SARS-CoV attack, the virus was detected in samples such as pharyngeal swab in all the two groups by Real-time PCR (RT-PCR) and virus isolation was performed. RESULTS: After virus attack, the level of SARS-CoV-specific IgG and neutralizing antibody were induced by SARS-CoV in the interferon group was weaker than in control group. Hematology items showed no apparent changes after virus attack in treated group. Through pathological examination, the morphology of the lung tissues of two Macaques in the treated group was normal, while the other three displayed the interstitial pneumonia with the thickened septum and infiltration with mononuclear cells. Among which, one monkey showed part of thickened septum fused with each other. These lesions in the interferon treated animals were similar to those seen in the animals in control group, but with smaller scope of pathological changes. No significant abnormity was detected in other organs. CONCLUSION: Recombinant IFN-alpha2b could effectively interdict or weaken SARS-CoV injury in monkeys.

Animals↗
PubMed2005

[Effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation on soil biological activities].

This paper studied the effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation in the south, central and upstate areas of subtropical China on the changes of soil chemical and biological properties. The results showed that after replacing with Cunninghamia lanceolata plantation, the total organic carbon (TOC) content in surface soil decreased by 31.51% - 58.24%, and the contents of soil total N and P, pH value, C/N and C/P also decreased to different degree. Soil microbial amount was less than that under natural secondary broad-leaved forest, soil urease, invertase, catalase and dehydrogenase activities decreased, while soil polyphenol oxidase activity increased by 8% - 40%. The respiration rate of Cunninghamia lanceolata soil was 51.15% - 54.48% lower than that of natural secondary broad-leaved forest soil. The correlation between soil TOC and polyphenol oxidase activity was negative (R = - 0.723, n = 18), while those between soil TOC, N, P and other enzyme activities were positive. It could be concluded that replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation worsened soil quality, and the loss of soil organic matter in Cunninghamia lanceolata plantation ecosystem might be one of the important factors resulted in the decrease of soil nutrients and enzyme activities.

Carbon↗
PubMed2005

[Expression and significance of KiSS-1 and its receptor GPR54 mRNA in epithelial ovarian cancer].

OBJECTIVE: To study the expression and significance of metastasis suppressor gene KiSS-1 and its receptor GPR54 in epithelial ovarian cancer. METHOD: The expression and their clinical significance of KiSS-1 and GPR54 were evaluated by RT-PCR in 37 patients with epithelial ovarian cancer, 15 patients with borderline epithelial ovarian tumors, 15 patients with epithelial benign tumors and 11 patients with normal ovarian tissues. RESULTS: The positivity and relative contents of KiSS-1 mRNA in patients with epithelial ovarian cancer (68%, 0.82 +/- 0.09) and borderline epithelial ovarian tumors (60%, 0.80 +/- 0.10) were all higher than in patients with epithelial benign tumor (20%, 0.65 +/- 0.10) and normal ovarian tissues (18%, 0.66 +/- 0.06; P < 0.05). The positivity and relative contents of KiSS-1 mRNA in patients with epithelial ovarian cancer correlated with their clinical stage and lymph node metastasis (P < 0.05). There was no difference in the positivity and relative contents of GPR54 mRNA between patients with epithelial ovarian cancer (70%, 0.79 +/- 0.07), borderline epithelial ovarian tumor (67%, 0.76 +/- 0.10), benign epithelial ovarian tumor (60%, 0.73 +/- 0.07) and normal ovarian tissues (45%, 0.78 +/- 0.08), respectively (all P > 0.05). The positivity and relative contents of GPR54 mRNA in patients with epithelial ovarian cancer did not correlate with their clinical stage, histology grade, lymph node metastasis and production of ascites (P > 0.05). CONCLUSION: KiSS-1 and GPR54 may play an important role in inhibiting the invasion and metastasis of early epithelial ovarian cancer.

Adult↗
PubMed2005

[Effects of glutamine on alpha-sarcomeric actin and its mRNA expression of myocardium in rats with endotoxemia].

OBJECTIVE: Endotoxemia is a serious syndrome resulting in multi-organ failure. Once it happens, the penetration of small intestine epithelium increases, body liquid losses, then effective circulating blood decreases and serious metabolic acidosis, serious hypotension, systolic failure, and even shock may occur. In this pathological process, endotoxin, tumor necrosis alpha and systolic dysfunction play important roles. Nowadays, many studies have been done to resolve the systolic dysfunction, but too much attention had been paid to the followings: the depressions of myocardium caused by tumor necrosis alpha, other inflammatory factors, endotoxin and metabolic acidosis; the disturbance of blood vessel-nerve regulations; nitric oxide (NO)/inducible nitric oxide synthase (iNOS) over-synthesis and the decreased density of beta-receptors in the myocardium and/or their activities. Little attention has been paid to the relationship between alpha sarcmeric actin (alpha-SA) and systolic dysfunction during endotoxemia. Glutamine (Gln) can be metabolized into glutathione, an eliminator of free radical. It has been used in preventing myocardial damage from reperfusion. This study aimed to observe the dynamic changes of alpha-SA and mRNA expressions in rats with endotoxemia and examine the effects of Gln on them. METHODS: Classical rat model of endotoxemia was established by intraperitoneal injection of LPS (4 mg/kg, Escherichia coli O55:B5, Sigma). 121 Wistar 18-day-rats were divided into three groups randomly, (1) 0 h control group (normal saline: 1 ml/kg, n = 11). (2) LPS group (LPS: 4 mg/kg, n = 55). (3) Gln group (LPS: 4 mg/kg and immediately 13.64%; Gln: 1 ml/kg, Fresenus, n = 55), Furthermore, LPS and Gln groups were divided into 2, 4, 6, 24 and 72 h time points (n = 11). Each time point of LPS and Gln as well as control rats were anaesthetized at each time point with 1% chloral hydrate injected intraperitoneally at the dosage of 1 ml/kg. Then rats were sacrificed at appoint time, and the hearts were isolated. Eight of them were put in 76 degrees C liquid nitrogen and then frozen in minute 80 degrees C icebox in order to measure the expression of alpha-SA mRNA by RT-PCR. Three of them were fixed in 4% formaldehydum polymerisatum for 12 to 16 h, then the expression of alpha-SA was detected by immunohistochemistry. RESULTS: (1) Compared to 0 h, the expressions of alpha-SA and mRNA in LPS group were significantly depressed (P < 0.01). In LPS group, the lowest was at 6 - 24 h, while in Gln group, it was postponed to 24 h. At 72 h, there was no difference in expressions of alpha-SA between Gln and 0 h group (P > 0.05). (2) Comparing at same time point, the expressions of alpha-SA were significant higher in Gln group than those in LPS group, while the expressions of alpha-SA mRNA in Gln group were high at 4-72 h. There was, however, no significant difference at early phase (P > 0.05). CONCLUSION: Alpha-SA and its mRNA expression were depressed in LPS-induced endotoxemia, especially from 6 to 24 h. It could damage the systolic function. alpha-SA decrease in endotoxemia was due to the inhibited synthesis other than the promoted degradation. Glutamine could inhibit the effects of LPS on both alpha-SA and its mRNA expressions.

Actins↗
PubMed2004

[Expression and significance of caspase-3 gene in apoptotic muscle cells 103Pd radioactive stent bile duct in dogs].

OBJECTIVE: To discuss the expression and significance of caspase-3 gene in the apoptotic muscle cells in gamma-radiation-induced muscle cell lines. METHODS: The caspase-3 mRNA in the control and gamma-radiation induced apoptotic muscle cells was analysed by RT-PCR. RESULTS: The expression of caspase-3 gene transcript was higher in 103Pd radioactive stent dog bile duct than in general stent dog bile duct, and apoptotic muscle cells were higher in 103Pd radioactive stent dog bile duct than in general stent dog bile duct. CONCLUSIONS: The high level expression of caspase-3 gene may help to understand the muscle cells sensitivity to gamma-radiation apoptosis. 103Pd radioactive stent may increase the expression of caspase-3 gene in dog bile duct and prevent the billiary narrow when dog bile duct was injured by balloon.

Animals↗
PubMed2004

[Effect of 103palladium radioactive stent on expression of smooth muscle actin in bile duct during healing process and its significance].

OBJECTIVE: To observe the effect of radiation on the expression of smooth muscle actin (SMA) in the bile duct during the healing process and the inhibitory function of (103)palladium (Pd) radioactive stent on the stricture of bile duct after injury. METHODS: Twelve mongrel dogs were made models of bile duct injury: duodenotomy was performed, a balloon catheter was inserted into the general bile duct and saline with high pressure was perfused thereinto to cause laceration of the mucosa, and then the balloon catheter was withdrawn and ordinary alloy stent or (103)Pd radioactive stent was inserted into the general bile duct. Thirty days after the dogs were killed. Their bile ducts were taken out to undergo HE staining to observe the area of general bile duct, thickness of the tunica intima, area of residual bile duct cavity, stricture degree, and circumference of bile duct. The expression of SMA in the bile duct tissue was detected by immunoistochemistry. RESULTS: SMA was expressed in 5 of the 6 specimens of bile duct in the (103)Pd radioactive stent group and 2 of the 6 specimens of the ordinary stent group (P < 0.01). The maximum thickness of tunica intima of general bile duct was 0.78 mm +/- 0.12 mm in the (103)Pd radioactive stent group, significantly less than that of the ordinary stent group (1.86 mm +/- 0.14 mm, P < 0.01). The percentage of maximum stricture area of the (103)Pd radioactive stent group was 23% +/- 16%, significantly lower that that of the ordinary stent group (56% +/- 22%, P < 0.01). The circumference of bile duct cavity of the (103)Pd radioactive stent group was 9.7 mm +/- 1.6 mm, significantly longer that of the ordinary stent group (7.0 mm +/- 1.4 mm, P < 0.01). CONCLUSION: (103)Pd radioactive stent reduces the expression of SMA in the bile duct during the healing process, thus inhibiting the stricture of bile duct caused by scar contracture at the anastomotic stoma.

Actins↗
PubMed2004

Preparation of magnetic polybutylcyanoacrylate nanospheres encapsulated with aclacinomycin A and its effect on gastric tumor.

AIM: To evaluate the effect of aclacinomycin A-loaded magnetic polybutylcyanoacrylate nanoparticles on gastric tumor growth in vivo and in vitro. METHODS: Magnetic polybutylcyanoacrylate (PBCA) nanospheres encapsulated with aclacinomycin A (MPNS-ACM) were prepared by interfacial polymerization. Particle size, shape and drug content were examined. Female BABL/c nude mice were implanted with MKN-45 gastric carcinoma tissues subcutaneously to establish human gastric carcinoma model. The mice were randomly divided into 5 groups of 6 each: ACM group (8 mg/kg bm); group of high dosage of MPNS-ACM (8 mg/kg bm); group of low dosage of MPNS-ACM (1.6 mg/kg bm); group of magnetic PBCA nanosphere (MPNS) and control group (normal saline). Magnets (2.5 T) were implanted into the tumor masses in all of the mice one day before the therapy. Above-mentioned drugs were administered intravenously to the mice of every group on the first day and sixth day. When the mice were sacrificed, tumor weight was measured, and the assay of granulocyte- macrophage colony forming-unit (CFU-GM) was performed on semi-solid culture. White blood cell, alanine aminotransferase and creatine were examined. 3-(4-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used to examine the viability of MKN-45 cells after incubation with different concentrations of ACM, MPNS and MPNS-ACM suspension respectively for 48 h. RESULTS: Content of ACM in MPNS-ACM was 12.0% and the average diameter of the particles was 210 nm. The inhibitory rates of ACM (8 mg/kg bm), high dosage of MPNS-ACM (8 mg/kg bm), low dosage of MPNS-ACM (1.6 mg/kg bm) and MPNS on human gastric carcinoma in nude mice were 22.63%, 52.55%, 30.66% and 10.22%, respectively. There was a significant decrease in the number of CFU-GM of bone marrow in ACM group compared with control group, whereas no obvious change was observed in that of the nanosphere groups. The values of 50% inhibition concentration (IC50) of ACM, MPNS and MPNS-ACM were 0.09, 97.78 and 1.07 microg/mL, respectively. CONCLUSION: The tumor inhibitory rate of MPNS-ACM was much higher than that of ACM under magnetic field and the inhibition on bone marrow was alleviated significantly compared with ACM group.

Aclarubicin↗
PubMed2004

Kinetic measurements of phosphoglucomutase by direct analysis of glucose-1-phosphate and glucose-6-phosphate using ion/molecule reactions and Fourier transform ion cyclotron resonance mass spectrometry.

A method for the direct determination of kinetic constants for phosphoglucomutase and its phosphorylated products is described. Fourier transform ion cyclotron resonance gas-phase ion/molecule reactions between trimethyl borate and glucose phosphate, phosphorylated at either the 1 or the 6 position, generate mass spectra distinguishable with regard to product ion distribution. A multicomponent quantification method is utilized to determine the composition of a binary mixture of the two positional isomers. Using this method, the conversion between glucose-1-phosphate and glucose-6-phosphate can be directly monitored without the use of coupling enzymes. The values of K(m) for glucose-1-phosphate and glucose-6-phosphate were determined using the substrate-velocity plot and the Haldane relationship, respectively. Values of V(max) for both the forward and the reverse directions were measured, and the equilibrium constant for the reversible reaction was determined using this methodology. Kinetic parameters measured correlate well with those obtained using traditional methods. The assay was demonstrated to be accurate and particularly convenient to determine kinetic constants for enzymatic systems that involve the interconversion of phosphorylated positional isomers.

Chemistry Techniques, Analytical↗
PubMed2004

Liver X receptors (LXRs) regulate apolipoprotein AIV-implications of the antiatherosclerotic effect of LXR agonists.

Liver X receptors (LXRs) regulate target genes that are critical in lipoprotein metabolism and atherosclerosis. Apolipoprotein AIV (ApoAIV) is an apolipoprotein that is associated with chylomicrons and high-density lipoproteins. Plasma ApoAIV level in humans is inversely correlated with coronary artery events and overexpression of ApoAIV in mice results in significant reduction in atherosclerosis. We report here that LXRs directly regulate apoAIV at the transcriptional level. Treatment of C57B6 mice with a synthetic LXR agonist, T0901317, resulted in significant increases in plasma apoAIV that was associated with high-density lipoprotein. Examination of both intestinal and liver apoAIV mRNA revealed specific increases in liver mRNA only. In a human heptoma HepG2 cell model, apoAIV mRNA was up-regulated upon the treatment with either native or synthetic LXR agonists. Nuclear run-on study revealed a significant increase in the ApoAIV transcriptional rate upon LXR activation. Examination of the human apoAIV proximal promoter revealed a potential LXR response element that demonstrated binding with HepG2 nuclear extracts. Cotransfection studies in HepG2 cells indicated that this responsive element was functional in mediating the human ApoAIV gene response to LXR agonists. In addition, we identified a functional LXR-responsive element at 3' end enhancer region of mouse ApoAIV gene. We conclude that ApoAIV is a direct target gene of LXRs that may contribute to the antiatherogenic effect of LXR activation.

Animals↗