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Biomedical subjects

G Hu

Publications and source records attributed to G Hu.

At least 163 records · Page 9Linked to original sources
PubMed1995

Multi-copy nuclear pseudogenes of mitochondrial DNA reveal recent acute genetic changes in the human genome.

Four nuclear pseudogenes homologous to the 10031-10195-bp region of the human mitochondrial genome were detected by constant denaturant capillary electrophoresis. Among them, one pseudogene is present as at least five copies in each cell, in accordance with our previous observations of multi-copy mitochondrial DNA pseudogenes. The presence of multiple identical copies of pseudogenes suggests that the human genome underwent a series of genetic changes, including gene amplifications, very recently in evolutionary history, i.e., within the last 390000 years.

Base Sequence↗
PubMed1995

Study on three dimensional reconstruction of transesophageal echocardiographic images.

Using biplane transesophageal echocardiography and the concept of three dimensional transthoracic echocardiography, we performed three dimensional reconstruction of transesophageal images of various clinicopathologic cases, including atrial septal defect, mitral stenosis, mitral valve prolapse and pulmonary stenosis. The hardware equipment and image processing flow chart of three dimensional reconstruction of transesophageal echocardiographic images are described. Our present study indicates that three dimensional reconstruction of transesophageal echocardiographic images could display multi-regional three dimensional structures of heart and great vessels, including superior vena cava, ascending aorta, right ventricular outflow tract, pulmonary artery and left heart, with clear, visual and stereoscopic imaging. The regional structures could be displayed at different levels of stereo-anatomic-sections and in different orientations of rotating stereo-images, which could provide accurate three dimensional anatomical information for cardiac stereo-morphological study and definition of spatial location and size of cardiac abnormalities.

Adolescent↗
PubMed1995

Inhibition of oncogene expression by green tea and (-)-epigallocatechin gallate in mice.

The effects of tea drinking on the tobacco-specific nitrosamine 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK)-induced mouse lung oncogene expression and the effect of topical application of the tea polyphenol component (-)-epigallocatechin-3-gallate (EGCG) on 12-O-tedradecanoylphorbol-13-acetate (TPA)-induced mouse skin oncogene expression were investigated. In the first experiment, mice were treated with NNK (1.3 mg/kg body wt ip) once a day for three days and were given 2% tea in drinking water during the whole experimental period. After four or eight weeks, the lung tissue of the mice treated with NNK displayed a significantly high level of expression in c-myc, c-raf, and c-H-ras oncogenes, and they were all inhibited by tea drinking with inhibitory rates of 50%, 20%, and 50%, respectively. In the second experiment, a single application of 10 nmol of TPA to mouse skin led to a marked increase in the transcripts' level of ornithine decarboxylase (ODC) gene, protein kinase C (PKC) gene, and c-myc oncogene at four hours after TPA administration. Topical application of EGCG (1 or 5 mumol) one hour before the application of TPA inhibited all TPA-induced gene expression in a dose-dependent fashion. These results confirm the anticarcinogenic effects of tea and suggest that a possible mechanism is the effect of tea on carcinogen-induced oncogene expression.

Animals↗
PubMed1995

Suppression of tumorigenesis by transcription units expressing the antisense E6 and E7 messenger RNA (mRNA) for the transforming proteins of the human papilloma virus and the sense mRNA for the retinoblastoma gene in cervical carcinoma cells.

Human cervical carcinoma cell lines that harbor human papilloma virus (HPV) have been reported to express HPV E6 and E7 proteins at least in the beginning stages if not at all stages of the disease. The HPV E6 and E7 proteins bind to and inactivate the products of the p53 and retinoblastoma (Rb) tumor suppressor genes, which thereby allow the cervical carcinoma cells to circumvent the action of these tumor suppressor genes. We observed that the introduction of the antisense HPV 18 E6 and E7 sequences, as well as a sense cDNA for the human wild-type Rb gene into a human cervical carcinoma cell line (HeLa), which is positive for the HPV 18 provirus, decreased the in vitro and in vivo growth rate of the transfected cells if both antisense transcripts for the HPV 18 E6 and E7 and sense transcripts for human Rb were expressed. In addition, overexpression of a complementary DNA (cDNA) for the Rb messenger RNA was sufficient to slow the proliferation of HeLa cells, and the level of Rb cDNA expression was correlated with the degree to which the rate of growth of the tumor was slowed. The results of our experiments show that the presence of HPV E6 and E7 proteins and the resultant inactivation of Rb in cervical carcinoma cells contributes to the neoplastic phenotype even in highly evolved cervical carcinoma cell lines such as HeLa, which have been derived from a cervical carcinoma patient at an advanced stage of the disease process. These data suggest that the HPV proteins play a role not only at the beginning of cervical cancer, but also at advanced stages of this disease. These experiments may lead to genetic approaches to the control of this disease that involve antisense sequences that downregulate the E6 and E7 genes or lead to expression of the Rb gene.

Animals↗
PubMed1995

(-)-Stepholidine antagonizes the inhibition by D2 receptor agonists on synaptosomal tyrosine hydroylase in rat corpus striatum.

AIM: To evaluate the action of (-)-stepholidine (SPD), a novel dopamine (DA) receptor antagonist, on inhibition by presynaptic D2 receptor agonists on the activity of synaptosomal tyrosine hydroxylase (TH) in the striatum. METHOD: The TH activity was measured by HPLC-ECD. RESULTS: The mixed DA receptor agonist apomorphine (Apo 10.4 nmol L-1) and selective D2 receptor agonists N-0437 (0.4 pmol L-1) and quinpirole (0.8 mumol L-1) inhibited the activity of TH, while selective D1 receptor agonist SKF 38393 (0.001-10 mumol L-1) and SPD (1-100 mumol L-1) failed to inhibit the TH activity. The inhibition of N-0437 and quinpirole were antagonized by D2 receptor antagonist spiperone and SPD. CONCLUSION: The negative feedback regulation of presynaptic DA receptors is mediated via D2 receptors and SPD is an antagonist on presynaptic D2 DA receptors.

Animals↗
PubMed1995

Modulation of cell spreading and migration by pp125FAK phosphorylation.

We provide evidence for both matrix-dependent and pp60v-src tyrosine kinase-dependent modulation of cell migration via tyrosine phosphorylation of pp125FAK, a focal adhesion kinase, thought to be involved in integrin-mediated signaling. Enhanced pp125FAK tyrosine phosphorylation and cell spreading was associated with decreased migration. Cells plated on type I collagen were less spread and exhibited lower levels of pp125FAK tyrosine phosphorylation and faster migration rates compared with cells on fibronectin that were well spread, which exhibited enhanced levels of pp125FAK tyrosine phosphorylation and slower migration rates. Inside-out signaling via expression of pp60v-src or its kinase-negative mutant caused a decrease in cell migration by changing the extent of pp125FAK tyrosine phosphorylation to above or below the levels obtained with control cells plated on fibronectin. Hence, pp125FAK tyrosine phosphorylation appears to play a role in the signaling cascade pathway involved in regulation of extracellular matrix-modulated, integrin-mediated cell migration.

3T3 Cells↗
PubMed1995

Dietary survey in a Chinese population.

OBJECTIVES: To assess food pattern and nutrition profile aiming at planning population-based nutrition intervention for chronic diseases control. DESIGN: A randomized survey. SETTING: The survey was carried out in Tianjin, one of the three largest cities in China. SUBJECTS: 3683 subjects aged 15-64 years old were selected by a random stratified multilevel cluster sampling. INTERVENTION: The diet was assessed by food weighing plus consecutive individual 3 day food records. RESULTS: Distinct differences in dietary pattern and nutrient intakes were found between subjects living in urban and rural areas. The diet of urban people was richer in fat and high quality protein compared with the diet of rural people. Low intakes of vitamin A, calcium, riboflavin, and zinc were found in both areas, the situation being worse in the rural areas. The sodium intake and sodium:potassium ratio was very high in both areas. Cholesterol intake was much higher among the urban people. CONCLUSION: The study suggests that integrated nutrition intervention is needed to prevent insufficient intake of some nutrients and control dietary risk factors related to chronic diseases.

Adolescent↗
PubMed1995

Associations between blood pressure and dietary intake and urinary excretion of electrolytes in a Chinese population.

OBJECTIVE: To examine the associations between blood pressure and sodium, potassium, calcium and magnesium in a cross-sectional study by 24-h urine collections and food weighing with 3-day food records in 328 males and 335 females in Tianjin, People's Republic of China. RESULTS: A very high sodium intake and sodium:potassium ratio was confirmed in the study population. After adjusting for confounding variables, both dietary and urinary sodium and sodium:potassium ratio were significantly and positively correlated with blood pressure. Although a negative correlation was found between potassium and blood pressure, the association was significant only between urinary potassium and systolic blood pressure in females and in both sexes combined. No significant associations were found between blood pressure and either intake of or urinary excretion of calcium and magnesium. The dietary intake correlated highly with urinary excretion of electrolytes. In both sexes a strong positive association was found between blood pressure and age, and between blood pressure and body mass index. Higher blood pressure was shown in subjects with higher sodium and alcohol intake, higher body mass index and lower potassium intake. CONCLUSION: The present results indicate that factors contributing to high blood pressure in Tianjin, People's Republic of China, are related to age, body mass index, high sodium intake and sodium:potassium ratio.

Adult↗
PubMed1995

Assessment of sodium and potassium in processed foods in an urban area in China.

OBJECTIVE: To identify commonly consumed processed foods with high sodium (Na) content and sodium to potassium (Na:K) ratio for the purpose of using this information in a community-based nutrition education programme. DESIGN: Calculations of Na and K intake were based on the data of a dietary survey carried out in Tianjin in 1992. All processed foods were randomly sampled based on manufacturers and market survey. SETTING: The survey was conducted in the urban area in Tianjin, China. PARTICIPANTS: 2317 subjects aged 15-64 years old were included in the dietary survey. The response rate was 95%. MAIN RESULTS: The mean sodium intake was 6517 mg in men and 5708 mg in women. 38% of the total Na intake came from processed foods and condiments in both of the urban men and women in Tianjin. 122 processed foods with sales volumes were identified. Most of the processed foods had high Na content and high Na:K ratio, especially Na-rich condiments, salted vegetables, fried dough cake and sausages. The Na content of most processed foods in Tianjin was higher than the mean value reported in the Chinese Food Composition Table. CONCLUSION: Processed foods contribute an important part of dietary Na in the urban diet in Tianjin. It is necessary to initiate nutrition intervention activities aiming at regulations on the Na content of processed foods and to advise the people to reduce consumption of salty foods.

Adolescent↗
PubMed1995

Relationship between muscarinic receptor subtypes and cyclic nucleotides in pons-medulla oblongata.

AIM: To study the relationship between muscarinic receptor (M-R) subtypes and cyclic nucleotides in pons-medulla oblongata (MeOb). METHODS: The contents of cGMP and cAMP in Sprague-Dawley rat pons-MeOb, cerebellum and cerebral cortex were assayed by radioimmunoassay and competitive protein-binding assay, respectively, after ip injections of drugs. Control rats were given ip normal saline. RESULTS: M1-R agonist pilocarpine (6, 15 mg kg-1, ip) increased the content of cGMP in the pons-MeOb and cerebral cortex, but did not bring about any noticeable change in the cAMP content. The increase of cGMP was antagonized by ip pirenzepine or scopolamine. On the other hand, ip M2-R agonist 6 beta-acetoxy nortropane (6 beta-AN) 25 micrograms kg-1 reduced not only cAMP contents in the pons-MeOb and cerebellum but also cGMP contents in the pons-MeOb and cerebral cortex, while 6 beta-AN 12 micrograms kg-1 only lowered cAMP content. The decreases of cGMP and cAMP induced by 6 beta-AN were antagonized by ip AF-DX 116 or atropine, respectively. CONCLUSION: Stimulation of M1-R causes the increase of cGMP and that of M2-R induces the decreases of both cGMP and cAMP in the pons-MeOb.

Animals↗
PubMed1995

Changes in sodium intake and blood pressure in a community-based intervention project in China.

A sodium intervention project was carried out in Tianjin, China, as part of the Tianjin Project, which is a national pilot, community-based intervention programme to reduce non-communicable diseases. The aim of this 3 year sodium project was to evaluate the feasibility and effects of sodium reduction in the population. The evaluation of the programme was based on examinations of independent cross-sectional population samples in 1989 (1719 persons) and in 1992 (2304 persons) in the intervention and matched reference areas. Food weighing and consecutive 3 day food records were used to measure dietary intake. The mean sodium intake fell 22 mmol/day in men and 11 mmol/day in women in the intervention area from 1989 to 1992. The reduction was significant in men (P = 0.001) and near significance in women (P = 0.05). The sodium intake increased significantly in men in the reference area. There was a significant net reduction in sodium intake in men in the intervention area. This reduction was similar in different educational and occupational groups suggesting that the intervention had reached the whole community. The mean systolic blood pressure (SBP) decreased 3 mm Hg for the total population and 2 mm Hg for normotensives in the intervention area. There was a significant net reduction in SBP both in all or in normotensive subjects. These results support the conclusion that community-based sodium intervention is feasible for hypertension prevention. However, the sodium intake is still very high in this population, which warrants further effective intervention.

Adolescent↗
PubMed1994

Angiogenin promotes invasiveness of cultured endothelial cells by stimulation of cell-associated proteolytic activities.

Angiogenin, a potent inducer of neovascularization in the chicken chorioallantoic membrane and rabbit cornea, promotes endothelial cell invasion of Matrigel basement membrane. A transformed bovine aortic endothelial cell line, GM 7373, is 5 times more invasive when cultured in the presence of 1 microgram of bovine angiogenin per ml than in its absence. A polyclonal anti-angiogenin antibody and alpha 2-antiplasmin neutralize the effect of angiogenin, but an angiogenin-binding protein (actin) does not. Further, this concentration of angiogenin induces a 14-fold increase in the cell-associated proteolytic activity of cultured endothelial cells, determined with a tissue-type plasminogen activator-specific peptide as the substrate. In addition, cells cultured on a three-dimensional fibrin gel in the presence of angiogenin are 3 times more capable of dissolving the gel and forming focal defects in the underlying matrix. The results indicate that angiogenin can enhance the ability of endothelial cells to digest extracellular matrix components and degrade basement membrane, thereby facilitating cell invasion and migration. Binding of angiogenin to its cell-surface binding protein (actin) followed by dissociation of the angiogenin-actin complex from the cell surface and subsequent activation of tissue-type plasminogen activator/plasmin are likely steps involved in the processes of endothelial cell invasion and angiogenesis.

Angiogenesis Inducing Agents↗