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Yan Gao

Publications and source records attributed to Yan Gao.

123 records · Page 7Linked to original sources
PubMed2002

[Role of NADH-cytochrome b(5) reductase in biosynthesis of thyroid hydrogen peroxide].

The activity of NADH-cytochrome b(5) reductase (b(5)R) and the levels of hydrogen peroxide in the thyroid of patients with Graves' disease (GD) and normal controls were measured with potassium ferricyanide as substrate and with the homovanillic acid fluorescence assay. The activity of b(5)R and the level of H2O2 in GD thyroid were definitely higher than those in normal control, but the activity of catalase in GD thyroid was not significantly different from that in normal thyroid. After addition of p-chloromercuribenzoate, a b(5)R inhibitor, the activity of b(5)R in GD and normal thyroid decreased by 85%, the level of H2O2 decreased by 50%, and protein-bound iodine (PBI) formation by 52%. There is a positive correlation between the level of H2O2 and the activity of b(5)R. Our data indicate that b(5)R participates in thyroid hydrogen peroxide biosynthesis, and is an important enzyme in the production of H2O2.

Case-Control Studies↗
PubMed2002

How Tlg2p/syntaxin 16 'snares' Vps45.

Soluble N-ethylmaleimide sensitive factor-attachment protein receptors (SNAREs) and Sec1p/Munc18-homologs (SM proteins) play key roles in intracellular membrane fusion. The SNAREs form tight four-helix bundles (core complexes) that bring the membranes together, but it is unclear how this activity is coupled to SM protein function. Studies of the yeast trans-Golgi network (TGN)/endosomal SNARE complex, which includes the syntaxin-like SNARE Tlg2p, have suggested that its assembly requires activation by binding of the SM protein Vps45p to the cytoplasmic region of Tlg2p folded into a closed conformation. Nuclear magnetic resonance and biochemical experiments now show that Tlg2p and Pep12p, a late- endosomal syntaxin that interacts functionally but not directly with Vps45p, have a domain structure characteristic of syntaxins but do not adopt a closed conformation. Tlg2p binds tightly to Vps45p via a short N-terminal peptide motif that is absent in Pep12p. The Tlg2p/Vps45p binding mode is shared by the mammalian syntaxin 16, confirming that it is a Tlg2p homolog, and resembles the mode of interaction between the SM protein Sly1p and the syntaxins Ufe1p and Sed5p. Thus, this mechanism represents the most widespread mode of coupling between syntaxins and SM proteins.

Amino Acid Motifs↗
PubMed2002

A robust inducible-repressible promoter greatly facilitates gene knockouts, conditional expression, and overexpression of homologous and heterologous genes in Tetrahymena thermophila.

The Cd(2+)-inducible metallothionein (MTT1) gene was cloned from Tetrahymena thermophila. Northern blot analysis showed that MTT1 mRNA is not detectable in the absence of Cd(2+), is induced within 10 min of its addition, is expressed in proportion to its concentration, and rapidly disappears upon its withdrawal. Similarly, when the neo1 gene coding region flanked by the MTT1 gene noncoding sequences was used to disrupt the MTT1 locus, no transformants were observed in the absence of Cd(2+), and the number of transformants was proportional to increased Cd(2+) concentration. The neo3 cassette, in which the MTT1 promoter replaced the histone gene HHF1 promoter of the previously used neo2 cassette, transformed cells at much higher frequencies than neo2 and produced germ-line knockouts where neo2 had failed. Rescuing the progeny of a mating of gamma-tubulin gene, GTU1, knockout heterokaryons with a GTU1 gene inserted into the MTT1 locus yielded >75 times more transformants than rescuing with the wild-type GTU1 gene itself. When cells rescued with the MTT1-GTU1 chimeric gene were transferred to medium lacking Cd(2+), they stopped growing and had phenotypic changes indistinguishable from cells containing only disrupted GTU1 genes. Thus, it is now possible to create conditional lethal mutants and study the terminal phenotypes of null mutations for essential genes by replacing the endogenous gene with one under the control of the MTT1 promoter. The MTT1 promoter also resulted in approximately 30 times more overexpression of the IAG48[G1] surface antigen gene of the ciliate fish parasite Ichthyophthirius multifiliis than the highly expressed BTU1 promoter, accounting for approximately 1% of the total cell protein. Thus, the MTT1 promoter should enable routine over-expression of endogenous and foreign genes in Tetrahymena.

Animals↗
PubMed2002

The circumsporozoite protein of Plasmodium falciparum is expressed and localized to the cell surface in the free-living ciliate Tetrahymena thermophila.

Heterologous expression is an important tool for characterization of protein function, structural studies, and production of antigen. While many different host systems have been utilized for the expression of Plasmodium falciparum proteins, the extreme AT-richness of its genome represents an obstacle to efficient expression. In addition, primary sequence motifs such as glycosyl phosphatidyl-inositol (GPI) cleavage/attachment sites of P. falciparum are not recognized in currently used expression hosts. Recently, DNA-mediated transformation has been used for expression of heterologous genes in the ciliated protozoan Tetrahymena thermophila. We report the stable expression of full-length P. falciparum circumsporozoite (CS) protein in T. thermophila. The expressed gene utilized the native CS protein N-terminal secretory signal sequence and the C-terminal GPI anchoring signal. Immunofluorescence imaging demonstrated that the CS protein was localized to the cell surface of Tetrahymena. Metabolic labeling with tritiated myristate resulted in incorporation of label into the recombinant CS protein, indicating that the protein was bound to the cell surface via a GPI anchor. This is the first report of the recognition of targeting and GPI anchoring signals of the P. falciparum CS protein in a heterologous expression host.

Animals↗
PubMed2002

Pump models assessed by transesophageal echocardiography during cardiopulmonary resuscitation.

OBJECTIVE: Transesophageal echocardiography was performed during closed-chest cardiopulmonary resuscitation (CPR) in in-hospital cardiac arrest to further explore the hemodynamic mechanism of CPR. METHODS: CPR attempts were performed according to advanced cardiovascular life support guidelines in 6 cases of in-hospital cardiac arrest. Multi-plane transesophageal echocardiography was carried out within 15 min of initiation of CPR. Throughout CPR, the motion of the mitral, tricuspid and aortic valves, the changes in the left ventricular cavity size and the thoracic aortic diameter were observed. Trans-mitral and trans-aortic Doppler files of blood flow were also documented. RESULTS: A closure of the mitral and tricuspid valves with simultaneous opening of the aortic valve occurred exclusively during chest compression, resulting in forward blood flow in the pulmonary and systemic circulation. Peak forward aortic flow at a velocity of 58.8 +/- 11.6 cm/s was recorded during the compression phase. Whereas, a closure of the aortic valve and rapid opening of the atrioventricular valves associated with ventricular filling during relaxation of chest compression was noted in all 6 patients. Peak forward mitral flow at a velocity of 60.6 +/- 20.0 cm/s was recorded during the release phase. Mitral regurgitation during the chest compression period was detected in 5 patients, reflecting a positive ventricular-to-atrial pressure gradient. A reduction in the left ventricular chamber and an increase in the thoracic aortic diameter during the compression phase was found in all patients, indicating that direct cardiac compression contributed to forward blood flow. CONCLUSION: These observations favor the cardiac pump theory as the predominant hemodynamic mechanism of forward blood flow during CPR in human beings.

Aged↗
PubMed2002

[Treatment of choroidal melanoma with X-ray knife].

OBJECTIVE: To detect and analyze the therapeutic effects of X-ray knife for treatment of choroidal melanoma with the fixation of the eyeball. METHODS: The average size of the tumors in 16 eyes of 16 cases was 11.8 mm x 10.0 mm x 4.5 mm. The eyeballs were fixed with four rectus retractable sutures under local anesthesia (no use of retrobulbar injection). The superior and inferior rectus sutures penetrated the upper and lower lids at the middle part of fornixes, and the four sutures were anchored at the positions: above the eyebrow, inferior orbital rim, root of nose and lateral orbital rim respectively and deep to the fascia. A stereotactic linear accelerator, Vrianc 2100 C, was used for the radiosurgery, with an average marginal dose 23.4 Gy. The mean follow-up time was 18.5 months. RESULTS: The tumors in 7 cases (43.8%) shrinked notably during 6 - 12 months after therapy. In the postoperative 1 - 2 years, the tumors in 11 eyes (68.8%) were decreased in size, among them, in 4 eyes only a flat scar remained and in 3 eyes the shrinkage was not significant. Enucleation was performed in 3 patients because of a little increase in size. The total local control rate was 81.3%. There were no marked side effects except small hemorrhages in or under the retina. Fixations of all eyeballs were very stable, and the orientation of radiotherapy was accurate. CONCLUSIONS: The therapeutic effects of choroidal melanoma with X-ray knife are quite good, and no significant complications are found. There is a higher rate of local control. The fixation of eyeball with four rectus sutures penetrating eyelids is very stable and reliable.

Adult↗
PubMed2002

[Expression of apoptosis-related protein in epithelial dysplasia and squamous cell carcinoma].

OBJECTIVE: To study the expression and significance of apoptosis-related protein p53, Bcl-2, and Bax during the development of oral squamous cell carcinoma (SCC). METHODS: The expression was observed in 10 normal oral epithelia, 48 dysplasia epithelia and 42 SCC by immunohistochemical evaluation. RESULTS: In normal mucosa, the positive rate of p53, Bcl-2 and Bax were 0%, 20% and 60%. In dysplasia epithelia, the positive rate of p53 is increased (P < 0.05), the positive rate of Bcl-2 and Bax remained no significant change (P > 0.05), but the positive intensity in severe dysplasia was higher than in mild group. In SCC, the positive rate of Bcl-2 increased significantly (compared with dysplasia, P < 0.05), while the expression of Bax was decreased with the increase of SCC histological grade. Further analysis showed the correlation was evident in p53 and Bax in dysplasia, and in p53 and Bcl-2 in SCC. CONCLUSIONS: In dysplasia, p53 gene mutation results in accumulation of dysplasia cells. In SCC, the cooperation of p53, Bcl-2 and Bax results in the progression of SCC. Apoptosis genes could work either independently or cooperatively.

Apoptosis↗
PubMed2002

[The changes in plasma leptin, insulin and proinsulin levels in obese adolescents].

OBJECTIVE: To investigate the metabolic changes in obese adolescents and the relationship between obese adolescents and metabolic syndrome. METHODS: 198 obese adolescents [body mass index (BMI) >/= 25 kg/m(2)] and 78 normal adolescents (BMI 18.5 approximately 23.0 kg/m(2)) were chosen from 2 217 middle school students of 14 approximately 16 years. The levels of serum leptin, insulin, proinsulin, glucose and lipids of these adolescents were measured and compared. RESULTS: (1) There was significant gender difference of serum leptin levels in adolescents of 14 approximately 16 years. The level of serum leptin was higher in female than that in male [(18.53 +/- 1.41) microgram/L vs (6.33 +/- 1.79) microgram/L]. (2) The levels of serum leptin, insulin and proinsulin of obese adolescents were significantly higher than those of normal adolescents [(19.94 +/- 1.91) microgram/L vs (11.27 +/- 2.04) microgram/L, (15.34 +/- 1.66) microIU/L vs (13.17 +/- 1.43) microIU/L and (16.19 +/- 1.64) pmol/L vs (11.79 +/- 1.70) pmol/L respectively]. (3) The levels of blood glucose and triglyceride of obese adolescents were significantly higher than those of normal adolescents [(4.63 +/- 0.50) mmol/L vs (4.13 +/- 0.33) mmol/L and (1.20 +/- 0.56) mmol/L vs (0.90 +/- 0.32) mmol/L respectively], but the levels of serum high-density lipoprotein cholesterol (HDL-C) of obese adolescents were significantly lower than those of normal adolescents [(1.14 +/- 0.24) mmol/L vs (1.38 +/- 0.26) mmol/L]. CONCLUSION: It is suggested that there are leptin resistance, insulin resistance and potential disorders of blood glucose and lipid metabolism in obese adolescents. Our study indicated that adolescent obesity would be related with early occurrence of type 2 diabetes.

Adolescent↗
PubMed2002

[The efficacy and safety of pioglitazone hydrochloride in combination with sulphonylureas and metfomin in the treatment of type 2 diabetes mellitus a 12-week randomized multi-centres placebo-controlled parallel study].

OBJECTIVE: To evaluate the efficacy and safety of pioglitazone hydrochloride 30 mg/day with sulphonylureas and metfomin in the treatment of patients with type 2 diabetes mellitus. METHODS: There were 283 patients treated with sulphonylureas and metfomin randomized in this multicenter double-blind placebo-controlled clinical trial. Patients who had 7.0 mmol/L </= fasting plasma glucose(FPG) < 13.0 mmol/L were randomized to receive placebo or pioglitazone 30 mg once daily for 12 weeks. RESULTS: The patients who had been treated with pioglitazone 30 mg showed significant decrease on average from baseline in FPG(1.1 mmol/L versus 0.4 mmol/L, P < 0.001), postprandial plasma glucose(PPG,1.5 mmol/L versus 0.3 mmol/L, P < 0.001), and glycosylated hemoglobin (HbA1c, 0.7% versus 0.4%, P < 0.01). AS for fasting plasma insulin (FIns) levels decreased, significant difference was also observed in the two groups (P < 0.05). HOMA-IR had significant mean decrease in the pioglitazone group as compared with placebo group (P < 0.01). CONCLUSION: Pioglitazone 30 mg/day for 12 weeks might improve the metabolic control and the insulin sensitivity in poorly controlled type 2 diabetes with previous administration of sulphonylureas and metfomin. It provides a safety and tolerance profile for type 2 diabetes mellitus in this trial.

Blood Pressure↗
PubMed2002

Mucinous adenocarcinoma of salivary glands.

OBJECTIVE: To investigate the clinicopathological features of mucinous adenocarcinoma of salivary glands. METHODS: The clinical manifestations and histopathological characteristics of 6 cases of mucinous adenocarcinoma of salivary gland were studied by retrospective and routine histopathology and immunohistochemistry. RESULTS: Four mucinous adenocarcinoma occurred in palate and 2 in mouth floor. Average age of patients was 60 years (48 - 70) and males were affected more often than females (4:2). Pathologically, the tumor grew with infiltration of surrounding tissues. The tumor consisted of unitary mucinous cells and mucin pool was obvious. The cell pleomorphism and nuclear mitosis were often seen. Some tumors showed acinus-like structure. Tumor cells often formed incomplete duct-like structure and small clusters floating in mucinous pool. There were intracellular mucin and signet ring cells in the tumor. Tumor cells showed positive reaction to PAS, Alcin blue, and some cytokeratin staining. CONCLUSIONS: Mucinous adenocarcinoma of salivary gland is a rare malignant tumor which mainly affects palate and mouth floor of older patients. The tumor may originate from acinic cell of mucous acinus or multi-potential cell of salivary gland.

Adenocarcinoma, Mucinous↗
PubMed2002

[Effect of propylene glycol mannate sulfate on blood lipids and lipoprotein lipase in hyperlipidemic rat].

AIM: To study the effect of propylene glycol mannate sulfate (PGMS) on blood lipids and lipoprotein lipase in hyperlipidemic rat, and its anti-hyperlipidemic mechanism. METHODS: PGMS was administered ig at different doses (37.8 mg.kg-1.d-1 and 75.6 mg.kg-1.d-1) to hyperlipidemic rats for three weeks and blood serum was obtained after starved 12 h. Total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were examined. The mRNA expression of lipoprotein lipase (LPL) in liver, spleen and artery was detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: PGMS significantly decreased the levels of TC, TG and LDL-C and increased that of HDL-C in hyperlipidemic serum dose-dependently. PGMS was shown to increase the level of LPL mRNA expression, which is related directly to the controlling effects of PGMS on blood lipids. CONCLUSION: PGMS modulated blood lipids by promoting mRNA expression of LPL. This may be one important mechanism of PGMS to modulate blood lipids.

Animals↗
PubMed2002

[Induction of CuZn-SOD mRNA expression and activity by PGMS in rat liver].

AIM: To study the effect of propylene glycol mannate sulfate (PGMS) on induction of CuZn-SOD. METHODS: Wistar rats were given PGMS p.o. at different doses (0, 18.9, 37.8 and 75.6 mg.kg-1.d) for ten days. Then the rats were sacrificed and the total RNA was extracted from the livers. The total RNA samples were loaded on a 1% agarose gel to detect the quality of total RNA. RT-PCR was applied to study the expression of CuZn-SOD mRNA in rat livers. The amplified products were detected by the 1.5% agarose gel electrophoresis. Simultaneously, the CuZn-SOD activities in rat liver were determined by nitrite method. RESULTS: The total RNA extracted from rat livers was integrated without being decomposed by RNase. The level of CuZn-SOD mRNA of the high-dosage group (75.6 mg.kg-1.d) was higher than that of the control group (0 mg.kg-1.d) (P < 0.01); the CuZn-SOD activities of the high-dosage group were significantly higher than those of the control group (P < 0.001) and the CuZn-SOD activities of the middle- (37.8 mg.kg-1.d) and low-dosage groups (18.9 mg.kg-1.d) were higher than those of the control group (P < 0.01). CONCLUSION: PGMS can increase the CuZn-SOD activities as well as CuZn-SOD on mRNA level. Therefore, it is possible for PGMS to counteract Atherosclerosis (AS) by inducing the expression of CuZn-SOD.

Animals↗
PubMed2002

[Quantitative study of the cellular nuclear DNA contents in odontogenic cysts and ameloblastoma].

OBJECTIVE: To investigate the proliferative potential of the epithelial cells in odontogenic keratocyst, radicular cyst, dentigerous cyst and ameloblastoma. METHODS: DNA contents and ploidy of basal and spinous cells in keratocyst, radicular cyst, dentigerous cyst, and the peripheral column cells and central reticular cells in ameloblastoma were analysis respectively. RESULTS: The more and higher DNA contents and the proliferating ploidy of keratocyst and ameloblastoma than those of radicular cyst and dentigerous cyst indicate the active proliferating potential. The spinous cells showed more active proliferating growth than the basal cells of keratocyst. The higher DNA contents of radicular cyst are related to the stimulus of the inflammation. The dentigerous cysts have more di-ploidy cells without active growth potential. CONCLUSIONS: The active cell proliferating growth in keratocyst and ameloblastoma is probably the pathological basis of their local aggressive biological behavior.

Ameloblastoma↗
PubMed2002

[Transfusion of activated immune cells induced fluctuations of HCV titer without mutations in hepatitis C virus core and E2 region CTL epitopes].

OBJECTIVE: To investigate the variations of HCV core and E2 region epitopes during transfusion of activated immune cells. METHODS: Four patients receiving transfusion of activated immune cells were under continuously observation. HCV titers were measured by quantitive PCR. HCV core and E2 regions were cloned and sequences were analyzed by computer software. RESULTS: During the follow-up the serum ALT levels and the HCV virus titers fluctuated greatly in each of these persons. After transfusion, no significant variations were observed in HCV core and E2 coding regions. CONCLUSIONS: The alteration of host immune attacks could induce the fluctuations of HCV load without any mutations in the currently observed coding genes of the epitopes.

Adult↗