Biomedical subjects

Y Ruan

Publications and source records attributed to Y Ruan.

At least 73 records · Page 4Linked to original sources

PubMed1996

[The role of platelet-derived growth factor and ras P21 in experimental hepatocarcinogenesis].

In order to explore whether platelet-derived growth factor (PDGF) is involved in hepatocarcinogenesis, expression of PDGF-beta chain and ras P21 were investigated using immunohistochemical method in hepatocarcinoma induced with diethylnitrosamine (DENA). Elevated PDGF-beta chain and P21 protein levels were found in hepatocytes in the early stages after DENA administration. Along with the progression of hepatocarcinogenesis, immunopositive cells were increased with the formation of various foci and nodules and the staining was usually stronger in the peripheral parts of nodules. In addition, PDGF-beta and P21 often expressed simultaneously in the smae lesions, where the cells were also positive for AFP expression. The results suggest that abnormal expression of PDGF might be an early specific event during hepatocarcinogenesis and might be involved in the malignant transformation of the hepatocytes by autocrine as well through ras P21 signal pathways.

Animals↗

PubMed1996

[Study on the morphometric and hemodynamic changes of the pulmonary arteries in pulmonary hypertension autopsies].

With the purpose of studying the relationship between the pathological gradings and changes of the hemodynamics as well as the collagen typing of the pulmonary arteries in pulmonary hypertension, 9 autopsy cases including 6 cases of unexplained plexogenic pulmonary arteriopathy, 2 cases of diffuse interstitial fibrosis of lung and 1 case of chronic embolic pulmonary hypertension were collected as the pulmonary hypertension group (PAH). The pathological lesions of PAH in pulmonary arteries were graded as follows: Grade I showed medial hypertrophy; Grade II medial hypertropy and intimal cellular proliferation: Grade III medial hypertrophy and intimal fibrosis or embolic occlusion: Grade IV the above lesions plus plexiform lesions with/without focal necrotizing arteritis. Immunohistochemical staining with antibodies against collagen type I and type IV was performed in the paraffin sections of lungs using PAP method. The result indicated that: 1) there were significant differences between the mean medial thickness in pulmonary arteries (6.1% in the normal lung group and 26.1% in PAH) and the density of pulmonary artery (22.6% arterioles/cm2 in the normal group and 44.6 arterioles/cm2 in PAH) respectively (P < 0.01). 2) there was positive correlation between the grades of PAH lesions and the mean pulmonary arterial pressure (r = 0.68 P < 0.01). 3) collagen type I fibriles increased in the old lesions and collagen type IV fibrils were dominant in the early stage of PAH (reversible lesion).

Adolescent↗

PubMed1996

[The inhibitory effects of Radix Astragali on hypoxic pulmonary hypertension of rats].

The inhibitory effects of Radix Astragali (RA) on hypoxic structural remodeling of intra-acinar pulmonary arteries (IAPA) and pulmonary hypertension (PHT) were studied in rats, which were fed in hypoxic environment under normal atmospheric pressure (10% O2 10 hours/day). 60 rats were divided into 3 groups; hypoxia group, hypoxia+RA group and control group. On the 15th and 30th day of hypoxia, right ventricular systolic pressure (RVSP) and right ventricle hypertrophy index (RVHI) were measured and pulmonary vessel changes were studies under light and electronic microscopes and morphometric analysis. Compared with the hypoxia+RA group, RA could prevent IAPA wall cell damage and dilate the constricted IPIA induced by hypoxia. RA could also inhibit hypertrophic changes in the tunica media and proliferation of adventitial cells of the IAPA and muscularization of non-muscular arteries. Therefore, preserving the IAPA wall cells and dilating IAPA by RA may play an important role in inhibiting structural remodeling of IAPA and pulmonary hypertension.

Animals↗

PubMed1996

[Studies of mast cell-mediated cytotoxicity to hepatoma cells in vitro].

The effects of mast cells (MCs) isolated from rat peritoneal cavity on rat hepatoma cell line (CBRH7919) in vitro were studied with phase contrast microscopy, scanning and transmission electron microscopy. The results showed that different degrees of degeneration were present in all CBRH7919 cells and a few of them exhibited necrosis or disruption when CBRH7919 cells were cocultured with MCs for 24 hours. In situ hybridization demonstrated that the expression of c-myc mRNA in CBRH7919 cells was markedly reduced by MCs. MTT colorimetric assay indicated that the supernatants of MC cultures had suppressive effect on the proliferation of CBRH7919. A monoclonal anti-mouse TNF antibody could decrease the suppressive effect. These results suggest that MCs had anti-tumor effect.

Animals↗

PubMed1995

The Drosophila insulin receptor contains a novel carboxyl-terminal extension likely to play an important role in signal transduction.

The nucleic acid and deduced amino acid sequence of the Drosophila insulin receptor homologue (dir) has been determined. The coding sequence of dir is contained within 10 exons spanning less than 8 kilobase pairs of genomic DNA. The deduced amino acid sequence of the dir encodes a protein of 2148 amino acids, larger than the human insulin receptor due to amino- and carboxyl-terminal extensions. The overall level of amino acid identity between the DIR and human insulin and insulin-like growth factor-I receptors is 32.5 and 33.3%, respectively. Higher levels of identity are found in exon 2 (45 and 43%, respectively) and in the beta subunit (50 and 48%, respectively), and the positions of most cysteine residues in the alpha subunit cysteine-rich domain are conserved. A novel, 400-amino acid, carboxyl-terminal extension contains 9 tyrosine residues, four of which are present in YXXM or YXXL motifs, suggesting that they function as binding sites for SH2 domain-containing signaling proteins. The presence of multiple putative SH2 domain binding sites in the DIR represents a significant difference from its mammalian homologues and suggests that, unlike the human insulin and insulin-like growth factor-I receptors, the DIR forms stable complexes with signaling molecules as part of its signal transduction mechanism.

Amino Acid Sequence↗

PubMed1995

Immunohistochemical detection of macrophage-derived foam cells and macrophage colony-stimulating factor in pulmonary atherogenesis of cholesterol-fed rabbits.

In order to investigate the role of monocyte/macrophages and their relationship to the expression of macrophage colony-stimulating factor (MCSF) in pulmonary atherosclerosis, lungs were excised from rabbits that had been fed for 60 and 90 days on a diet containing 0.5% cholesterol. In the lungs, fatty streaks and elevated foam cell lesions predominated in the large or medium-sized elastic pulmonary arteries, while massive accumulation of foam cells in the intima of muscular arteries produced marked luminal narrowing and nearly complete occlusion. In these lesions, most of the foam cells were reactive with RbM2, a monoclonal antibody (mAb) against rabbit macrophages, while smooth muscle cell-derived foam cells were detected by mAb against smooth muscle actin in the deeper area of elevated foam cell lesions of elastic arteries. Ultrastructural observation confirmed the presence of monocytes in the intima, their differentiation into macrophages, and their transformation into foam cells in the atherosclerotic lesions. Immunohistochemical expression of MCSF was demonstrated in the endothelial cells, smooth muscle cells and foam cells. A minor macrophage-derived foam cell population was demonstrated to possess a proliferative capacity. These data suggest that MCSF is involved in the differentiation of monocytes into macrophages, their transformation into foam cells, and their proliferation during pulmonary atherogenesis.

Animals↗

PubMed1995

The c Fos immunoreactivities in the developing and adult rat cerebella.

c Fos immunoreactivities were studied by immunohistochemistry in the developing and adult rat cerebella. c Fos immunoreactivities were observed in purkinje cells early in postnatal development (P26 d) and reached a peak by P40-P60 d, followed by a decline in the 3-month-old adult. The granule cells revealed c Fos immunoreactivities by P26 d but declined until P50 d. Then c Fos immunoreactivities increased in the granule layer by P50-P60 d and decreased again in the adult. The deep nuclei showed c Fos immunoreactivities by P40 d and persisted in the adult. In spite of the difference in the patterns of location in c Fos immunoreactivities from the early postnatal period to adulthood, no decrease in the amount of c Fos immunoreactivity was evident from immunoblotting studies. Thus, it is concluded that c Fos immunoreactivities change from development to adult, but this does not affect the total amount of c Fos protein expression in the cerebellum.

Age Factors↗

PubMed1995

[In situ expression of c-myc, N-ras during diethylnitrosamine induced hepatocarcinogenesis].

In order to investigate the action of oncogenes in experimental hepatocarcinogenesis, the expression of c-myc, N-ras and H-ras were studied during early and late stages of DENA induced hepatocarcinogenesis in rats by using in situ hybridization. The results showed that overexpression of c-myc and N-ras was presented in teh proliferation hepatocytes and alternated hepatocytes foci during the early stage of hepatocarcinogenase, and with the formation and progression of hyperplastic hepatocytic nodules, the overexpresion cells of both were increased and often accompanied each other. Overexpression of H-ras appeared in the middle stage of hepatocarcinogenesis. The data obtained indicate that the abnormal expression of N-ras and c-myc in the hepatocarcinogenesis is not only an earlier molecule event which may relate to the initiation of HCC, but also the molecular basis for the morphogenesis of HCC, and these two functions took synergically. However, the abnormal expression of H-ras may have a promotive effect on the development of preneoplastic lesions, and also suggests that the malignant transformation of hepatocyte needs the cooperation of multiple oncogenes.

Animals↗

PubMed1994

PCR-based construction of promoter/G-free templates for in vitro transcription analysis allows selection of plasmids with optimal activity in homologous extracts.

In vitro transcription has been used for dissecting transcriptional controls in many eukaryotic systems. One modification which greatly reduces background non-specific transcription is the placement of a guanosine-free (G-free) region of DNA immediately downstream from a promoter [Sawadogo and Roeder, Proc. Natl. Acad. Sci. USA 82 (1985) 4394-4398]; transcription in the presence of RNase T1 and 3' O-Me-GTP eliminates non-specific transcripts, and produces the G-free transcripts initiated at the promoter. Restriction site-based fusion of a G-free cassette downstream from promoters is complicated by the requirement for G nucleotides to be excluded from the coding strand downstream from the transcription start points. We present an approach to add a G-free template onto a eukaryotic promoter by combining PCR-based termini construction and terminal deoxynucleotidyl transferase extension. The pisatin demethylase promoter (PDA1p) of the filamentous fungus Nectria haematococca was used as the test promoter. Three PDA1p/G- free constructs were tested in heterologous Drosophila melanogaster and HeLa and homologous N. haematococca transcription extracts. Each extract produced a PDA1p-specific transcript from each construct, but the relative level of transcription between constructs varied, particularly in the homologous extract. Since the choice of G-free sequence influences transcription differently among systems, this method for producing multiple G-free constructs should be useful for constructing and selecting optimal promoter/G-free templates for in vitro transcription in other homologous systems.

Animals↗

PubMed1994

In vitro transcription from the Nectria haematococca PDA1 promoter in an homologous extract reflects in vivo pisatin-responsive regulation.

The PDA1 gene of Nectria haematococca MP VI (anamorph: Fusarium solani) encodes pisatin demethylase. This enzyme detoxifies the isoflavanoid phytoalexin pisatin produced by the plant on which this fungus is pathogenic. Expression of pisatin demethylase activity is induced in a mycelium by pretreatment with pisatin. We have developed homologous in vitro system which accurately initiates transcription from the PDA1 promoter. Transcription levels in vitro reflect the same pisatin-responsive stimulation as measured for PDA1 mRNA in vivo, and are dependent upon sequences in the 5' upstream region of PDA1. Pisatin-responsive transcription from the PDA1 promoter indicates that initiation of transcription is a major regulatory step in the pisatin induction of pisatin demethylase expression.

Base Sequence↗

PubMed1994

In vitro transcription and binding analysis of promoter regulation by a host-specific signal in a phytopathogenic fungus.

The PDA1 promoter of the phytopathogenNectria haematococca MPVI (anamorph Fusarium solani) offers a model for regulation of a fungal virulence gene in response to plant host-specific signals. Expression of the PDA1 gene, encoding pisatin demethylase, is induced in culture by pisatin, the isoflavanoid phytoalexin of pea. This pisatin induction is suppressed by nutritional factors. We have been studying the mechanism of pisatin induction through in vitro identification of regulatory factors and regulatory elements of the PDA1 promoter. We have developed an in vitro transcription system for N. haematococca which accurately initiates at the PDA1 promoter and reflects the pisatin induction of PDA1 mRNA observed in vivo. This in vitro activity allowed a functional test of a limited set of 5' upstream deletions in the PDA1 promoter. In vitro binding studies have identified a DNA binding factor which is appears in mycelial extract after treatment of the mycelium with pisatin. This pisatin-responsive factor binds to a minimum size region of 35 bp approximately 500 bp upstream of the transcription initiation site. Tests using the in vitro transcription assay and in vivo competition both indicate a role for this binding region in the high expression of PDA1 under pisatin-induced conditions. Southwestern blotting has identified one component of this binding activity to be a approximately 35 kDa protein. The availability of these functional and structural tests of function, in conjunction with complementary in vivo tests, allow the detailed dissection of the signal pathway leading from exposure of the cell to pisatin towards the activation of PDA1 transcription.

Animals↗

PubMed1994

[Hydroxyapatite for laryngotracheal framework reconstruction].

This paper reported combined sternohyoid myocutaneous flap and hydroxyapatite (HA) graft for laryngotracheal reconstruction in clinical and experimental studies. HA rings were employed for reconstructing the laryngotracheal framework in 10 patients on the base of animal experiment. The implant was well taken in all cases without any rejection, resulting in excellent airways. The study demonstrates that this procedure can be used in treatment of severe laryngotracheal stenosis.

Adolescent↗

PubMed1994

Attenuation by alpha,beta-methylenadenosine-5'-triphosphate of periarterial nerve stimulation-induced renal vasoconstriction is not due to desensitization of purinergic receptors.

We investigated in the isolated rat kidney the modulation of vasoconstrictor responses to ATP (0.05-0.5 mumol), renal nerve stimulation (RNS) (0.5-10.0 Hz), norepinephrine (NE) (0.15-0.9 nmol), angiotensin II (2 pmol) and arginine vasopressin (3 pmol) by alpha,beta-methylenadenosine-5'-triphosphate (alpha beta mATP) infused at 6 microM (Procedure I) or for short intervals (5 min) at a low concentration (60 nM) gradually increased to 6 microM to reduce the dramatic initial vasoconstriction (Procedure II). Infusion of alpha beta mATP (Procedure I) produced a marked, transient rise in perfusion pressure of 146 to 198 mm Hg that returned to basal level within 10 min and thereafter inhibited the vasoconstrictor response to ATP, RNS (0.5-6.0 Hz), NE, angiotensin II and arginine vasopressin. Infusion of alpha beta mATP by Procedure II produced a smaller maximal transient increase in perfusion pressure (< 100 mm Hg) and reduced the vasoconstrictor responses to RNS at 0.5 to 2.0 Hz and to the lower dose of NE (0.15 nmol) only. ATP infusion reduced the vasoconstrictor response to both RNS and NE. In animals pretreated with reserpine, the effect of RNS to produce vasoconstriction was inhibited. These data suggest that ATP does not contribute to the renal vasoconstrictor response elicited by RNS, and that attenuation of renal vasoconstrictor responses by alpha beta mATP is not due to desensitization of purinergic receptors.

Adenosine Triphosphate↗

PubMed1991

Preparation and certification of lyophilized human urine for trace metals reference material in China.

The preparation of lyophilized human urine certified reference material (CRM) was established on the basis of literature in other countries and domestic conditions. The homogeneity and stability of the CRM accord with the stipulations. The certified values were determined by 14 high level laboratories in China using nine methods with different principles and have been examined by the National Institute for Occupational Safety and Health (NIOSH) using Inductively Coupled Plasma--Mass Spectrometry (ICP-MS). This CRM has been approved as first grade national reference material. It can be used in quality control of routine analysis, test of new methods, and as standard material for calibration of analytical instruments and as certified reference material for quantity transmission and analysis arbitration.

China↗

PubMed1991

[Distribution of muscarinic receptors of different affinities in smooth muscle of human stomach].

Muscarinic receptors of high and low affinity were found in the fundus and the body of human stomach through the contraction experiment combined with ligand method in vitro. The 2 types of muscarinic receptors with different affinity regulated respectively the contractions of the longitudinal and the circular muscle of human gastric fundus and gastric body. However, in the antrum exists only one kind of muscarinic receptors of high affinity, which regulated the contractions of the longitudinal and the circular muscles of human stomach. The contractile force of the longitudinal muscle induced by exogenous ACh in the fundus and that in the body of human stomach were found to be similar to each other. The contractile force of the circular muscle in the body was found to be the strongest, and the contractile force of both longitudinal and circular muscles in antrum was weaker.

Acetylcholine↗

PubMed1990

Hemolysin as a marker for Serratia.

All Serratia marcescens strains (total of 33) of different sources were hemolytic including clinical strains previously classified as being nonhemolytic. DNA fragments of the two hemolysin genes hybridized with the chromosomal DNA of S. marcescens, S. liquefaciens, S. kiliensis, S. grimesii, S. proteamaculans, S. plymutica, S. rubridaea which were also hemolytic. The restriction pattern of the hemolysin locus differed in each strain. S. ficaria and S. marinorubra expressed a different hemolysin which was much smaller than the S. marcescens hemolysin since it diffused through dialysis membranes. The DNA of the latter strains did not hybridize with the S. marcescens hemolysin DNA probes. Some S. marcescens strains, S. kiliensis and S. liquefaciens also expressed in addition the small hemolysin. No hybridization was found with DNA of Escherichia coli, Salmonella typhimurium, Proteus mirabilis, Proteus vulgaris, Citrobacter freundii, Enterobacter cloacae, Klebsiella arerogenes, Klebsiella pneumoniae, Shigella dysenteriae, Yersinia enterocolitica, Yersinia pseudotuberculosus, Listeria sp., Aeromonas sp., Legionella sp. and a Meninococcus sp., indicating that the hemolysin DNA probes are specific for Serratia, or that the hemolysin genes occur rarely in genera other than Serratia.

Autoradiography↗

PubMed1990

Function and localization of high and low affinity binding sites to muscarinic receptors in longitudinal and circular smooth muscles of human stomach.

The contractile response to acetylcholine (ACh) and the binding of [3H]-quinuclidinyl benzilate [( 3H]QNB) to muscarinic receptors in both longitudinal and circular muscles were examined in fundus, body and antrum of human stomach which was obtained by surgical operation for gastric cancer or ulcer. The values of pD2 and pA2 for ACh and atropine, respectively, on longitudinal muscle of fundus were similar to those of body but were larger than those of antrum. On the other hand, the values of pD2 and pA2 on circular muscles were not different among fundus, body, and antrum and were similar to those on longitudinal muscle of antrum. By Scatchard analysis of receptor binding of [3H]QNB in homogenate, at least two subclasses of binding sites, i.e. high and low affinity sites, were observed in fundus and body, while only high affinity binding site was found in antrum. Thus, we conclude that there are at least two subclasses of muscarinic receptors which regulate the contraction of smooth muscle in different regions of human stomach.

Acetylcholine↗

PubMed1989

Ultrastructural and immunocytochemical characterization of the cellular phenotype in primary adenoid liver tumours of the rat.

The cellular phenotype of 34 primary adenoid liver tumours induced in rats with N-nitrosomorpholine was studied by immunocytochemical and electron microscopical methods in order to elucidate the histo- and cytogenesis of these tumours. Three types of ducts were distinguished in the adenoid liver tumours at the ultrastructural level being characterized as of hepatocellular, transitional and cholangiocellular phenotype. The transitional cells took an intermediate position between the hepatocellular and the cholangiocellular phenotype. Frequent features of the hepatocyte-like differentiation were large round nuclei with a dispersed chromatin, glycogen-associated ER complexes, peroxisomes and the formation of bile canaliculi. Evidence for the relationship to bile ductular cells was provided by the regular association with a basement membrane, the (inconstant) positive immunohistochemical reaction for cytokeratin polypeptide KA-4, a poorly developed ER and small mitochondria. An additional finding in the ducts with a transitional cellular phenotype was the selective accumulation of mast cells integrated into the epithelium. Intimate associations between cells of the hepatocellular, transitional and cholangiocellular phenotype were observed at the light and electron microscopic level. The results suggest that a transdifferentiation (metaplasia) from cells with a hepatocellular to those with a transitional or cholangiocellular phenotype takes place in many liver tumours.

Adenoma↗