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Biomedical subjects

X Sun

Publications and source records attributed to X Sun.

At least 469 records · Page 26Linked to original sources
PubMed1995

[Expression of oncogene and anti-oncogene in mouse lung cancer induced by coal-burning smoke].

Previous epidemiology studies have shown association between coal burning and human lung cancer. To confirm relationship of coal burning to lung cancer formation and progression the expression of p53 and c-myc in 13 mouse lung cancer induced by coal-burning smoke and 5 mouse lung tissue control was studied by DNA-RNA in situ hybridization (ISH). Nine of 13 specimens showed c-myc overexpression but it occurred only 1 in 9 in the adjacent tissue. There was overexpression of p53 mRNA in all 13 lung cancer and 5 adjacent tissues. None in the controls was expression of p53 and c-myc detected. When compared to controls, there was significant higher expression of c-myc gene (P = 0.002) and p53 gene (P = 0.0001). The results confirm that overexpression of p53 and c-myc are common molecular events of lung cancer by coal-burning smoke and provide further evidence that smoke from coal burning is a causative agent of lung cancer.

Adenocarcinoma↗
PubMed1995

[A quantitative study on nuclear DNA content and morphological parameters in ovarian cystadenocarcinoma].

OBJECTIVE: To study nuclear DNA content and morphological parameters in ovarian cystadenocarcinoma. METHODS: Nuclear DNA content and morphological parameters were quantitatively determined by image analysis technology in 56 cases of ovarian cystadenocarcinoma, 12 benign ovarian cystadenoma and 10 normal ovarian epithelial tissue. RESULTS: DNA content of ovarian cystadenocarcinoma was the highest among the three groups; and there were significant differences between the groups (P < 0.01). In the aspect of morphometry, nuclear circle was greatly different among the three groups (P < 0.01). There was no significant variances in nuclear parameter and area (P > 0.05). Nuclear DNA content of ovarian cystadenocarcinoma was related to its histopathological classification, histological grade and clinical stages (P < 0.01, P < 0.05). There was a reverse relationship between the DNA ploidy level and clinical prognosis. The 2-year survival rate of ovarian cystadenocarcinoma with diploidy/near diploidy pattern was higher than that with aneuploid pattern (P < 0.01). CONCLUSIONS: Nuclear DNA content of ovarian cystadenocarcinoma is a useful marker in reflecting the biological behavior and is of practical value in diagnosis, the choice of treatment methods and in the evaluation of results and prognosis.

Adolescent↗
PubMed1995

[The study of p53 gene mutation in human bladder cancer].

Alteration of p53 gene and the molecular biological difference between superficial and invasive bladder cancer were investigated by polymerase chain reaction-single strand conformation polymorphism analysis and direct sequencing technique. p53 gene mutations were examined in exon region 5 to 8 in 21 bladder cancers. Only one of 14 superficial bladder cancers was found to have p53 gene mutation. Four of 7 invasive bladder cancers with T2, T3 and T4 were found to have p53 gene mutation. p53 gene mutation was found none of the 4 cancers with grade 1, only one of cancers with grade 2, four of 12 cancers with grade 3. These results suggest that p53 gene play an important role in the development of human bladder cancer.

Carcinoma, Transitional Cell↗
PubMed1995

[Exploration on oral preparations of Chinese materia medica by semi-bionic extraction].

In the light of biopharmacy, the present new technology to extract oral preparations of Chinese traditional medicinal by semi-bionic method was designed. In the technological process, the prescribed drugs were decoction and extracted first in an acid solution with a certain value and then in an alkaline solution with ther pH value. Afterwards, the extracts were filtered concentrated, dried and made into preparation. The theoretical basis of this technology was analysed and the concrete procedures were introduced, with Shaaogan Zhitong pill as an example.

Drugs, Chinese Herbal↗
PubMed1995

[Intelligence study on 1758 deaf children in China].

In order to determine the character of mental development and the influencing factors of childhood deafness in China the revised H-NTLA was applied to 1758 deaf children within the age range of 3 to 17 years. Compared with 1788 normal hearing children, the results showed that (1) the deaf children were about 20 points lower in IQ than those with normal hearing; (2) the average retardation was found to be about 6 months in 3-5 years old age, the difference became significant from 6 years old, the average retardation was found to be 36 months during 13 years old; (3) the scores were the same as those of the normal hearing children for block patterns, paper folding and puzzle blocks in 3-9 age groups; for visual attention span and spatial reasoning in 16-17 age groups. The scores were retarded significantly on picture association, picture analogies, memory for color and digits; (4) the influencing factors were found with stepwise regression model to be audiphone wearing, education fee and the beginning age of education.

Adolescent↗
PubMed1995

Clinical and pathologic studies on idiopathic uveal effusion.

In order to investigate the clinical features, pathology and treatment of idiopathic uveal effusion syndrome, ten eyes of seven patients with the syndrome had been studied. In addition to general clinical examinations, indirect opthalmoscopy, fundus fluorescein angiography and (FFA) ultrasonography were used to make definite diagnoses. The findings of these examinations indicate four key features of the idiopathic uveal effusion syndrome. They are: annular cilio-choroidal detachment, shifting non-rhegmatogenous retinal detachment, unremarkable inflammation in the anterior segment, and normal intraocular pressure. The fundus change is characterized by the "leopard-spot". All patients were treated by sclerectomy and sclerotomy, ciliochoroidal detachments disappeared soon after surgery, and retinal detachments resolved later on. Patients' visual acuity recovered well. The histochemical and electron microscopic examinations of excised tissues from five eyes showed thickened sclera, a general increase of the scleral fibril width compared to normal scleral, the disruption of normal lamellar arrangement of the scleral fibers and the deposition of glycosaminoglycans in the interfibrillar spaces. All these indicate that a congenital scleral abnormality seems to be the basic pathophysiology of the idiopathic uveal effusion syndrome.

Adult↗
PubMed1994

PAF and TNF increase the precursor of NF-kappa B p50 mRNA in mouse intestine: quantitative analysis by competitive PCR.

NF-kappa B, a nuclear transcription factor, is involved in the regulation of inflammatory cytokines. We have previously reported that PAF and TNF induce intestinal injury in rats and mice and the interaction of TNF and PAF probably plays a central role in its pathogenesis. In the present study, we developed a competitive PCR method to quantitate the transcripts of NF-kappa B p50/p105 gene, and investigated the effects of PAF and TNF on p50/p105 gene expression in the small intestine of C3H/HeN mice - p105 is the precursor of the p50 subunit of NF-kB. We found that NF-kappa B p50/p105 gene is constitutively expressed in the normal small intestine in small quantities (7.05 +/- 1.04 attomol/micrograms total RNA). PAF at a dose (1 microgram/kg) causing no systemic changes (e.g., hypotension, hemoconcentration), markedly increased intestinal p50/p105 transcripts within 30 min. TNF, at dose (1 mg/kg) also insufficient to induce systemic changes, increased intestinal p50/p105 gene expression, although its effect was much slower than PAF. The effect of TNF was not blocked by WEB 2086, a PAF antagonist. Our results indicate that both PAF and TNF stimulate the expression of NF-kappa B p50/p105 in vivo. However, the mechanisms of their respective actions are probably different.

Animals↗
PubMed1994

Allosteric control of the substrate specificity of the anaerobic ribonucleotide reductase from Escherichia coli.

The reduction of ribonucleotides is catalyzed by different enzymes in aerobic and anaerobic Escherichia coli, each with a different primary and quaternary structure. Here, we describe the allosteric regulation of the substrate specificity of the anaerobic ribonucleoside triphosphate reductase. The enzyme reduced ribonucleotides at a low basal rate. Reduction was stimulated up to 10-fold by an appropriate modulator (dGTP for ATP reduction, ATP for CTP and UTP reduction, and dTTP for GTP reduction). dGTP and dTTP inhibited the reduction of the "incorrect" substrate; dATP inhibited reduction of all four. From kinetic, effector binding, and competition experiments we conclude that the enzyme has two classes of sites, one that binds ATP and dATP and regulates pyrimidine ribonucleotide reduction ("pyrimidine site"), the other that binds dATP, dGTP, and dTTP and regulates purine ribonucleotide reduction ("purine site"). This model differs slightly from the model for the aerobic reductase, but the physiological consequences remain the same and explain how a single enzyme can provide a balanced supply of the four dNTPs. The similarity of a highly sophisticated control mechanism for the aerobic and anaerobic enzymes suggests that both arose by divergent evolution from a common ancestor, in spite of their different structures.

Adenosine Triphosphate↗
PubMed1994

Reconstitution of human TFIIA activity from recombinant polypeptides: a role in TFIID-mediated transcription.

Human TFIIA activity is composed of three subunits (alpha, beta, gamma). Here we report the isolation of a human cDNA clone encoding the gamma-subunit and the reconstitution of TFIIA activity from recombinant polypeptides (holo-TFIIA). Protein-protein interaction analysis established that the beta and gamma subunits of TFIIA interact with the TBP component of TFIID. The alpha-subunit is recruited into the complex by association with the gamma-subunit. Functional studies indicate that recombinant TFIIA stimulates basal TFIID-dependent transcription but is without effect on TBP-dependent transcription. Our studies indicate that TFIIA not only functions by physically removing negative components present in TFIID (antirepression), as demonstrated previously, but that it can stimulate basal transcription through components of the TFIID complex. Holo-TFIIA also stimulated activation of transcription in vitro as well as in vivo in transfected HeLa cells.

Amino Acid Sequence↗
PubMed1994

Two different cellular redox systems regulate the DNA-binding activity of the p50 subunit of NF-kappa B in vitro.

The NF-kappa B/Rel/Dorsal (NRD) transcription factor family binds target DNA sequences through their conserved N-terminal basic region that contains a single cysteine residue flanked by basic residues. This cysteine residue plays a critical role in the regulation of the DNA-binding activity of NRD members, since chemical modifications of this residue modulate the DNA-binding activity of NRD members. Here we show that cellular factors regulate the DNA-binding activity of NRD members in vitro by reduction-oxidation (redox) mechanisms. Two cellular redox systems, thioredoxin/thioredoxin reductase and apurinic/apyrimidinic endonuclease (also called Redox factor-1), independently, as well as, synergistically stimulate the DNA-binding activity of bacterially synthesized (recombinant) p50, one of the subunits of NF-kappa B that is a major NRD factor inducible in various types of cells. Since the mutation of the conserved residue (Cys61) in the N-terminal basic region of p50 impairs the stimulation of p50 DNA-binding activity by these redox factors, the regulation of p50 DNA-binding activity by these redox factors is mediated through this cysteine residue. It is, therefore, possible that these two cellular redox systems could play independent, as well as synergistic roles in the regulation of NF-kappa B functions in vivo through the redox control of their DNA-binding activity.

Amino Acid Sequence↗
PubMed1994

Blood coagulation factor Va abnormality associated with resistance to activated protein C in venous thrombophilia.

A coagulation test abnormality, termed activated protein C (APC) resistance, involving poor anticoagulant response to APC is currently the most common laboratory finding among venous thrombophilic patients. Because the anticoagulant activity of APC involves inactivation of factors Va and VIIIa, studies were made to assess the presence of abnormal factors V or VIII. Diluted aliquots of plasma from two unrelated patients with APC resistance and thrombosis were added to either factor VIII-deficient or factor V-deficient plasma and APC resistance assays were performed. The results suggested that patients' factor V but not factor VIII rendered the substrate plasma APC resistant. When factor V that had been partially purified from normal or APC resistant patients' plasmas using immunoaffinity chromatography was added to factor V-deficient plasma, APC resistance assays showed that patients' factor V or factor Va, but not normal factor V, rendered the substrate plasma resistant to APC. Studies of the inactivation of each partially purified thrombin-activated factor Va by APC suggested that half of the patients' factor Va was resistant to APC. These results support the hypothesis that the APC resistance of some venous thrombophilic plasmas is caused by abnormal factor Va.

Adult↗
PubMed1994

AA1, a newly synthesized monovalent lipophilic cation, expresses potent in vivo antitumor activity.

Certain lipophilic cations have been reported to display anticarcinoma activities because of their selective uptake and retention by mitochondria of cancer cells. Thus, these agents may comprise a unique class of agents directed against carcinoma. After screening more than 1000 lipophilic cations, we found that the monovalent lipophilic cation, 2,6-bis(4-amino-phenyl)-4-[4-(dimethylamino)phenyl]thiopyrylium chloride (AA1), displayed remarkable anticarcinoma activity both in vitro and in vivo. Unlike most other lipophilic cations, AA1 is stable and displays minimal light sensitivity. In vitro testing showed that AA1 was 10 times more toxic to the carcinoma cell line CX-1 than to the normal epithelial cell line CV-1. In vivo animal experiments showed that AA1 significantly prolonged the survival of mice implanted with tumors. For C57BL x DBA/2 F1 mice implanted with the mouse bladder carcinoma cell line, MB49, the treated:control ratio was 344%. For Swiss nu/nu mice implanted i.p. with the human melanoma cell line, LOX, the treated:control ratio was 341%. The most significant observation was obtained with Swiss nu/nu mice that were implanted i.p. with the human ovarian cell line, OVCAR-III. The treated:control ratio in this situation was greater than 450%. In all these tumor models, AA1 produced minimal toxicities. AA1 exhibited little inhibition of electron transport in isolated rat liver mitochondria; however, it inhibited mitochondrial ATPase with 50% inhibitory concentration of 6 microM. Compared with previously reported anticarcinoma lipophilic cations such as rhodamine 123 and dequalinium chloride, AA1 appeared to display more effective in vivo anticarcinoma activity. Thus, AA1 could be considered for further clinical development as a candidate for anticarcinoma chemotherapy.

Adenocarcinoma↗
PubMed1994

Development of the excitation-contraction coupling apparatus in skeletal muscle: peripheral and internal calcium release units are formed sequentially.

The development of calcium release units and of transverse tubules has been studied in skeletal muscle fibres from embryonal and newborn chicken. Three constituents of calcium release units: the tetrads, the feet and an internal protein directly associated with junctional surface of the sarcoplasmic reticulum are visualized by various electron microscope techniques. Evidence in the literature indicates that the three components correspond to the voltage sensors, the sarcoplasmic reticulum calcium release channels and the calcium binding protein calsequestrin respectively. We recognize two stages at which important events in membrane morphogenesis occur. The first stage coincides with early myofibrillogenesis (starting at approximately embryonal day E5.5), and it involves the assembly of calcium release units at the periphery of the muscle fibre in which feet and the internal protein are identified. Groups of tetrads also are present at very early stages and their disposition indicates a relation to the feet of peripheral couplings. Thus three major components of the excitation-contraction coupling pathway are in place as soon as myofibrils develop. The density of groups of tetrads in the surface membrane of primary and secondary fibres is similar, despite differences in developmental stages. The second stage involves the formation of a complex transverse tubule network and of internal sarcoplasmic reticulum-transverse tubule junctions, while peripheral couplings disappear. This stage starts abruptly (between E15 and E16) and simultaneously in primary and secondary fibres. It coincides with the myotube-to-myofibre transition. The two stages are separated by a relatively long intervening period (between E9 and E16). During the latter part of this period some primitive transverse tubules appear, and form junctions with the sarcoplasmic reticulum, but they remain strictly located at the periphery of the fibre and are not numerous. Finally, after the second stage there is a prolonged (up to 4 weeks) period of maturation, during which density of free sarcoplasmic reticulum increases, triads acquire a location at the A-I junction and fibre type differences appear. We conclude that a system for calcium uptake, storage and release exists at the periphery of the myotube during early myogenesis. The complexity of the system and its ability to deliver calcium through the entire fibre develop in parallel to the formation of myofibrils.

Animals↗