Search PubMed⌕ Search

Biomedical subjects

G Sun

Publications and source records attributed to G Sun.

At least 181 records · Page 10Linked to original sources
PubMed1997

[Plasmid DNA fragments from Halobacterium halobium active as eubacteria promoters in Escherichia coli].

In this paper; a promoter-probe plasmid pKK232-8 was used as a vector which functioned in E. coli. The plasmid pHH205 of Halobacterium halobium J7 was digested by two groups of restriction endonucleases BamHI-SalI and HindIII -SalI, recombined in vitro and transformed into E. coli. The transformants were selected on resistance plates to contain ampicillin (Am) and chloramphenicol (Cm). From random-selected 20 strains of transformants we obtained transformants T1 and T2, whose level of Cm resistance got to 110 micrograms/ml. The recombinant plasmids from T1 and T2 were named pJH and pJB, respectively. The resultes of analysis by restriction endonucleases digestion and molecular hybridization showed that recombinant plasmid pJH carried a inserted fragment with size of 800bp from plasmid pHH205. Experimental results of retransfomation proved further that the DNA fragment had promoter function in E. coli. Thus, this indicated that DNA fragments from plasmid of archaebaeteria (H halobium) may function as eubacteria (E. coil) promoters.

Escherichia coli↗
PubMed1997

[Novel mutations identified in exon 7 of phenylalanine hydroxylase gene in Chinese].

Exon 7 of the phenylalanine hydroxylase (PAH) gene was analyzed in 45 children affected with classic phenylketonuria (PKU) from northern China by using PCR-single strand conformation polymorphism (PCR-SSCP) technique and DNA direct sequencing. Six missense mutations (i.e. R243Q, R241H, G247V, L249H, P254I and G257V) and one silent mutation (V245V) were identified. The latter three missense mutations were demonstrated as novel mutations in comparison with the PAH mutation Database. One missense mutation (R241H) was first documented in Chinese. Our results showed population and regional differences in the PAH mutation distribution and suggest that there is more than one founding population for PKU in China. The finding of novel mutations will enhance our capability in molecular diagnosis of PKU.

Child↗
PubMed1997

[Quantitative analysis of prevention effect of tetrandrine on pancreatic islet beta cells injury in rats].

OBJECTIVE: To observe the preventive effect of tetrandrine (TET) on pancreatic islet beta cells damaged by alloxan in rats with HE, Gomori aldehyde fuchsine staining and immunocytochemistry. METHODS: Animal diabetic models were prepared with alloxan (50 mg/kg i.v.). Pancreatic islet beta cells density (BD) in the section of HRP-SPA immunocytochemistry staining was determined with weibel square system. RESULTS: The BD in experimental groups pretreated with TET (100 mg/kg) at 1.5 hours, 5 hours prior to alloxan injection increased from the control value of 13 +/- 4 to 62 +/- 9 and 65 +/- 7 (P < 0.001), which had no evident difference compared with the BV in normal control group; while the BV (22.5 +/- 7.7) in the pretreated group at 7 hours prior to alloxan injection also increased compared with the control group. But it was much lower than that in the normal control group. When the doses of TET decreased from 100 mg/kg to 50 mg/kg and 25 mg/kg, the BD declined from 62 +/- 9 to 45 +/- 5 and 38 +/- 4 (P < 0.01 and P < 0.001). CONCLUSION: Tetrandrine can protect islet beta cells a from injury induced by alloxan.

Alkaloids↗
PubMed1997

[Clinical significance of detection of PML-RAR alpha fusion gene of APL during differentiation therapy with ATRA].

OBJECTIVE: To characterize of the expression patterns of PML-RAR alpha fusion gene during differentiation therapy with ATRA. METHODS: A "neated" RT/PCR was established and subsequently used to study on 74 Acute Promyelocytic Leukemia (APL). RESULTS: Two major isoforms (type S and L) were detected in leukemia cells from 44 novel patients with APL. 19 of 44 (43.2%) patients with type S isoforms were accompanied with poor prognosis. 15 cases were detected sequentially by the RT/PCR method for dynamic observation of MSD during postremission therapy with ATRA and chemotherapy alternatly. The positive rate was 46.7% in 6 months after CR, then the positive rate curve tended to down wards gradually from 33.5% (12 months after CR) to 26.7% (24 months after CR), 11.1% (36 months after CR), 8.3% on 48 months after CR. Other 30 cases of APL which are long-term survivals and received the same postremission program were detected by the RT/PCR method. The expression of the fusion gene reversed positivty in two cases on 56 and 60 months respectively, then both relapsed. One case was detected regularly once a year for 3 times. In another case, the fusion gene was detectable whoever was no any abnormal evidence in peripheral blood and bone marrow 26 cases were negative and had a long-term survival CCR of 47-114 months (medium 66). CONCLUSION: The detection of RT/PCR PML-RAR alpha fusion gene plays an important role in clinical diagnosis, evaluation of prognosis and prediction of relapse in APL.

Adolescent↗
PubMed1996

Synthesis of chiral 1-(2'-amino-2'-carboxyethyl)-1,4-dihydro-6,7-quinoxaline-2,3-diones: alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor agonists and antagonists.

Recently discovered 6,7-disubstituted quinoxaline-2,3-diones, 1, have been found to antagonize specific binding and functional responses to both alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and kainic acid. Although a variety of studies have analyzed the activity of quinoxaline-2,3-diones with various substitutions at positions 6 and 7, there is little information regarding the effects of N-substitution. A racemic mixture of 1-(2'-amino-2'-carboxyethyl)-1,4-dihydroquinoxaline-2, 3-dione (QXAA, 2, R1 = R2 = H) has been synthesized from 1 (R1 = R2 = H). This compound inhibited specific [3H]AMPA binding but not [3H]kainate binding. IC50 values for QXAA, AMPA, and DNQX were 0.69, 0.012, and 0.74 microM, respectively. The R- and S-enantiomers were prepared by asymmetric synthesis. The S-isomer (2b) was 160-fold more potent in binding assays than the R-isomer (2d), with IC50 values of 0.23 and 38 microM, respectively. Both enantiomers were agonists in a functional assay, with the S-isomer having an EC50 value of 3 microM while that for the R-isomer was greater than 1 mM. Methyl substitutions at positions 6 and 7 (2a and 2c) resulted in antagonist compounds characterized by the S- and R-isomers being nearly equipotent, with IC50 values of 51 and 22 microM in the binding assay and EC50 values of 290 and 300 microM in the functional assay. AMPA had an EC50 value of 11 microM and DNQX an EC50 value of 30 microM in the functional assay. Analogs of quinoxalinediones with side chains other than an amino acid moiety on the nitrogen did not show good binding activities.

Animals↗
PubMed1996

A novel membrane receptor with high affinity for lysosphingomyelin and sphingosine 1-phosphate in atrial myocytes.

Activation of IK(ACh) is the major effect of the vagal neutrotransmitter acetylcholine in the heart. We report that both lysosphingomyelin (D-erythro-sphingosyl-phosphorylcholine; SPC) and sphingosine 1-phosphate (SPP) activate IK(ACh) in guinea pig atrial myocytes through the same receptor with an EC50 of 1.5 and 1.2 nM, respectively. Pertussis toxin abolished the activation of IK(ACh) by either lipid. The putative receptor showed an exquisite stereoselectivity for the naturally occurring D-erythro-(2S,3R)-SPC stereoisomer, the structure of which was confirmed by mass spectroscopy and NMR. These lipids caused complete homologous and heterologous desensitization with each other but not with ACh, indicating that both act on the same receptor. This receptor displays a distinct structure-activity relationship: it requires an unsubstituted amino group because N-acetyl-SPC, lysophosphatidic acid and lysophosphatidylcholine were inactive. Because SPP and SPC are naturally occurring products of membrane lipid metabolism, it appears that these compounds might be important extracellular mediators acting on a family of bona fide G protein-coupled receptors. Expression of these receptors in the heart raises the possibility that sphingolipids may be a part of the physiological and/or pathophysiological regulation of the heart. Based on their ligand selectivity we propose a classification of the sphingolipid receptors.

Animals↗
PubMed1996

Inhibition of prolactin receptor gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin in MCF-7 human breast cancer cells.

Treatment of MCF-7 human breast cancer cells with 10 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) did not decrease prolactin receptor (PRLR) binding. In contrast, PRLR mRNA levels were significantly decreased within 12 h after treatment with TCDD and persisted for up to 48 h. The effects of TCDD on PRLR mRNA levels were inhibited by the aryl hydrocarbon (Ah) receptor antagonist alpha-naphthoflavone and were not observed in Ah nonresponsive benzo[alpha]pyrene-resistant MCF-7 cells. These results suggest that the effects of TCDD were mediated through the Ah receptor. After treatment of MCF-7 cells with 10 nM 17 beta-estradiol (E2), there was a 2.3-fold increase in PRLR mRNA levels, and in cells cotreated with E2 plus TCDD, there was a 72% decrease in E2-induced PRLR mRNA levels. Previous studies have showed that TCDD also effects estrogen receptor (ER) binding and mRNA levels through the aryl hydrocarbon receptor pathway; however, the effects of TCDD on PRLR levels and binding in MCF-7 cells were different from those previously observed for ER.

Benzoflavones↗
PubMed1996

Functional analysis of the preproendothelin-1 gene promoter in pulmonary epithelial cells and monocytes.

At least two human preproendothelin-1 mRNAs are produced by a single gene through the use of different promoters, and the mechanisms controlling the production of these alternative transcripts might be cell-specific. In human lung, endothelin-1 is produced by vascular endothelial cells, bronchial epithelial cells, and pulmonary monocytes/macrophages. Given the important role of endothelin-1 in the pathogenesis of some pulmonary diseases, we carried out a functional analysis of the preproendothelin-1 gene promoter(s) in bronchial epithelial cells and lung monocytes. Two distinct preproendothelin-1 mRNAs were expressed in the two cell populations. Using deletion mutants and enhancer trap transfection experiments, we also identified different regions of the preproendothelin-1 gene necessary for endothelin-1 expression in bronchial epithelial cells and pulmonary monocytes.

Base Sequence↗
PubMed1996

Psychological long-term effects of sterilization on anxiety and depression.

Two-thousand cases (500 women and 500 men with sterilization; 500 women and 500 men without sterilization) in two counties and two cities in Sichuan, China, were investigated between 15 September 1992 and 30 April 1993. Information was obtained about their age, parity, marriage, contraceptives, social behavior, and present psychological characteristics. CES-D, SAS, and E.P.Q. scales were used to assess the depressive symptomatology, anxiety, and personality of the subjects. The results revealed that sterilization psychologically affected the depressive symptoms and anxiety under the neutral personality. In addition, depressive symptoms and anxiety were related to the subjects' age, educational level, income, operative doctors' attitudes to sterilization acceptors, and subjects' understanding of the sterilization.

Adult↗
PubMed1996

Three two-component signal-transduction systems interact for Pho regulation in Bacillus subtilis.

The Pho regulon of Bacillus subtilis is controlled by three two-component signal-transduction systems: PhoP/PhoR, ResD/ResE, and the phosphorelay leading to the phosphorylation of SpoOA. Two of these systems act as positive regulators, while the third is involved in negative regulation of the Pho regulon. Under phosphate-starvation-induction conditions, the response regulator (RR) PhoP, and the histidine protein kinase (HK) PhoR, are involved in the induction of Pho-regulon genes including the phoPR operon and genes encoding the major vegetative alkaline phosphatases, phoA and phoB. ResD (the RR) and ResE (the HK) are positive regulators of both aerobic and anaerobic respiration in B. subtilis. Current data suggest that they are also positive regulators of the Pho regulon, as is the transition-state regulatory protein AbrB. Data presented reveal that ResDE and AbrB are involved in activation of the Pho regulon through separate regulatory pathways. SpoOA approximately P (RR) exerts a negative effect on the Pho regulon through its repression of AbrB, and possibly through repression of ResDE. Both pathways converge to regulate transcription of the phoPR operon.

Alkaline Phosphatase↗
PubMed1996

The chemotactic activity of T-lymphocytes in response to interleukin 8 is significantly decreased in patients with psoriasis and atopic dermatitis.

Involvement of T-lymphocytes in the pathogenesis of psoriasis and atopic dermatitis is well established. The question arises as to whether not only tissue infiltrating but also circulating T-lymphocytes are involved in the disease process. Therefore we sought to determine whether T-lymphocytes from patients with psoriasis and atopic dermatitis show abnormal biological behavior to the proinflammatory chemokine interleukin 8 (IL-8) in vitro as studied by their chemotactic activity. In addition, the expression of T-cell activation markers such as HLA-DR and interleukin 2 receptor (IL-2R) were analysed with FACS-technique. In all, 25 patients with psoriasis (13 patients with severe psoriasis and 12 patients with mild psoriasis) and 11 patients with atopic dermatitis were investigated. For comparison. T-lymphocytes from 14 healthy controls were tested equally. The results show that T-cell chemotactic responses to IL-8 were significantly decreased in patients with severe psoriasis as compared to healthy controls. T-cells from patients with atopic dermatitis demonstrated an even more pronounced decrease in chemotactic response as compared to T-cells from psoriasis patients or healthy controls. In contrast, increased expression of activation markers HLA-DR and IL-2R were demonstrated in circulating T-cells from patients with severe psoriasis and atopic dermatitis in comparison to healthy controls. It can be concluded that circulating T-cells in patients with severe psoriasis and atopic dermatitis show a decreased in vitro chemotactic response to IL-8. Furthermore, the in vivo phenotypic activation state of T-lymphocytes in these patients seemed to be associated with their decreased in vitro functional capacity.

Adolescent↗
PubMed1996

Regulators of aerobic and anaerobic respiration in Bacillus subtilis.

Two Bacillus subtilis genes, designated resD and resE, encode proteins that are similar to those of two-component signal transduction systems and play a regulatory role in respiration. The overlapping resD-resE genes are transcribed during vegetative growth from a very weak promoter directly upstream of resD. They are also part of a larger operon that includes three upstream genes, resABC (formerly orfX14, -15, and -16), the expression of which is strongly induced postexponentially. ResD is required for the expression of the following genes: resA, ctaA (required for heme A synthesis), and the petCBD operon (encoding subunits of the cytochrome bf complex). The resABC genes are essential genes which encode products with similarity to cytochrome c biogenesis proteins. resD null mutations are more deleterious to the cell than those of resE. resD mutant phenotypes, directly related to respiratory function, include streptomycin resistance, lack of production of aa3 or caa3 terminal oxidases, acid accumulation when grown with glucose as a carbon source, and loss of ability to grow anaerobically on a medium containing nitrate. A resD mutation also affected sporulation, carbon source utilization, and Pho regulon regulation. The data presented here support an activation role for ResD, and to a lesser extent ResE, in global regulation of aerobic and anaerobic respiration i B.subtilis.

Aerobiosis↗
PubMed1996

[The inhibitory effects of serum of patients with acute promyelocytic leukemia on the formation of megakaryocytopoiesis colony unit].

OBJECTIVES: To determine if the sera of patients with acute promyelocytic leukemia (APL) and all-trans retinoic acid (ATRA) inhibit the formation of colony-forming-unit of megakaryocyte (CFU-Meg). METHODS: By cellular culture assay, the sera of 22 APL patients treated with ATRA and 10(-6)' mol/L ATRA were kinetically used to perform the investigation. Meanwhile, serum tumor necrosis factor (TNF) activity and bone marrow CFU-L were also detected. RESULTS: Before treatment, there was an inhibitory activity on CFU-Meg in the serum of APL patients (29.6% +/- 2.4%). The activity reduced gradually with the treatment and was stimulus when bone marrow remission obtained (-18.7% +/- 4.1%, P < 0.001). It was positively correlated with TNF activity in the serum and the number of CFU-L however negatively correlated with the number of megakaryocyte in bone marrow and PLT. Serum TNF activity and the number of CFU-L before treatment were higher than those after treatment (P < 0.05 and < 0.001, respectively). ATRA could stimulate the growth of CFU-Meg. CONCLUSIONS: There was an inhibitory activity in the serum of APL patients which could be used to monitor the efficacy of the therapy. ATRA stimulates the growth of CFU-Meg.

Adolescent↗
PubMed1996

[The effects of retinoic acid on the ultrastructure of cultured fibroblasts].

The paper reports the effects of retinoic acid on the ultrastructure of cultured fibroblasts. Electron microscopic observation (SEM and TEM) showed that fibrous substances on the cell surface and outside the cell had decreased. The results indicated that retinoic acid inhibits collagen synthesis of fibroblasts. The possible mechanism of the effect of retinoic acid in the treatment of scar is discussed.

Collagen↗
PubMed1996

[The relationship between the high inducibility genotype of CYP450IA1 and lung cancer susceptibility].

OBJECTIVE: To evaluate the role of polymorphism of CYP450IA1 gene in the susceptibility of lung cancer. METHODS: The polymorphism of CYP450IA1 gene in 149 lung cancer patients and 208 healthy controls were investigated by PCR technique. RESULTS: The high inducibility genotype (Val/Val type) of CYP450IA1 in lung cancer patients was 16.1%, which was significantly higher than that of controls, 8.7%. According to pathological classification of lung cancer, it was indicated that VAl/Val type in squamous carcinomas was the highest, 21.54%, which was significantly higher than that of controls (8.7%) and adenocarcinomas (8.00%). The Val/Val type in small cell carcinoma reached 17.6%. The relative risks were estimated according to smoking condition and CYP450IA1 genotype. Taking the risk of the category with non-smoking and non-high inducibility genotype (Val/ Val) to be at a baseline of 1.0, the odds ratio was 1.6 (P < 0.05) in non-smoking in non-smoking and Val/Val type 4.8 in smoking and Val/Val type (P < 0.001). The relative risk of Val/Val type was 2.2 times as non-Val/ Val type for smoking people. CONCLUSIONS: Development of lung cancer was associated with the high inducibility genotype of CYP450IA1. And Val/Val genotype of CYP450IA1 gene might be an important host hereditary marker for susceptibility to lung cancer.

Adenocarcinoma↗
PubMed1996

[G-CSF and all-trans retinoic acid-induced leukocytosis].

During the treatment with all-trans retinoic acid (ATRA) for acute promyelocytic leukemia (APL), leukocytosis occured in 33%-75% of the treated cases. ELISA method was used in detecting levels of serum granulocyle colony-stimulating factor (G-CSF) in 47 cases of APL during treatment with ATRA. It was found that the peak of increased serum G-CSF level occurred on the 9th day, and WBC number was highest on the 11th day. After ATRA treatment, both serum G-CSF level and WBC number increased in 68.1% of the cases. In 19.2% of the cases treated, serum G-CSF level was increased but without obvious change in WBC number, and the reverse was true in 12.7% of the cases. Serum G-CSF level was statistically correlated to the number of WBC, promyelocytes and its late stage by Spearman rank correlation analysis.

Adolescent↗
PubMed1996

[Long-term observation of the treatment of blepharoptosis by frontalis-aponeurosis suspension].

During the past 6 years, 78 cases of blepharoptosis were treated with the forked frontalisaponeurosis suspension technique. The main characteristic of this procedure was that the frontalis-aponeurosis was properly cut longitudinally so that the upper eyelid was elevated completely and the elevating force scattered. Thirty-six cases were followed up, with the longest time being 75 months. Most patients were satisfied with the results. We conclude that this procedure is the first choice for moderate or severe blepharoptosis or recurrent blepharoptosis after other operations.

Adolescent↗