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Biomedical subjects

S Luo

Publications and source records attributed to S Luo.

At least 145 records · Page 8Linked to original sources
PubMed1997

[Experimental study and clinical application of arterialized venous skin flap].

In order to investigate the survival mechanism and the role of venous drainage in arterialized venous skin flap, 60 rabbits' ears were used for research and clinical application of the flap was performed subsequently in two cases. The rabbits were divided into 4 groups. Experimental group was standard arterialized venous skin flap, control 1 group was venous skin flap, control 2 group was arterialized venous skin flap with only one drainage vein and control 3 group was normal skin flap. The process of survival of the flaps was observed by hemodynamic and histological method. The results showed that there was no significant difference between standard arterialized venous skin flap and normal skin flap (P > 0.01). Two cases of arterialized venous skin flap survived completely. The conclusion were as follow: 1. the opening of collateral circulation between the veinlets was the main change of the microcirculation; 2. the blood flow of the graft was changed from unphysiological circulation to physiological circulation as the time elapsed and 3. amelioration of venous drainage was important in inproving the survival rate of arterialized vein graft.

Adult↗
PubMed1996

Alternative splicing of the Na(+)-Ca2+ exchanger gene, NCX1.

We describe an analysis of the NCX1 gene and show that various tissues express different alternatively spliced forms of the gene. Alternative splicing has been confirmed by the genomic analysis of the Na(+)-Ca2+ exchanger gene. We also describe the Drosophila Na(+)-Ca2+ exchanger as having many of the same structural characteristics of the mammalian exchangers and this locus as possibly undergoing alternative splicing in the same region that has been described in the NCX1 gene. The general structure of the exchangers is similar to that of the alpha-subunit of the (Na(+)+ K+)-A Pase. Finally, sequence comparison of the various molecules demonstrates that structural characteristics of these molecules are more strongly conserved than the primary sequence of these products.

Alternative Splicing↗
PubMed1996

A new alpha-conotoxin which targets alpha3beta2 nicotinic acetylcholine receptors.

We have isolated a 16-amino acid peptide from the venom of the marine snail Conus magus which potently blocks nicotinic acetylcholine receptors (nAChRs) composed of alpha3beta2 subunits. This peptide, named alpha-conotoxin MII, was identified by electrophysiologically screening venom fractions against cloned nicotinic receptors expressed in Xenopus oocytes. The peptide's structure, which has been confirmed by mass spectrometry and total chemical synthesis, differs significantly from those of all previously isolated alpha-conotoxins. Disulfide bridging, however, is conserved. The toxin blocks the response to acetylcholine in oocytes expressing alpha3beta2 nAChRs with an IC50 of 0.5 nM and is 2-4 orders of magnitude less potent on other nAChR subunit combinations. We have recently reported the isolation and characterization of alpha-conotoxin ImI, which selectively targets homomeric alpha7 neuronal nAChRs. Yet other alpha-conotoxins selectively block the muscle subtype of nAChR. Thus, it is increasingly apparent that alpha-conotoxins represent a significant resource for ligands with which to probe structure-function relationships of various nAChR subtypes.

Acetylcholine↗
PubMed1996

Deimination of glycogen phosphorylase b by peptidylarginine deiminase. Influence on the kinetical characteristics and dimer-tetramer transition.

The kinetics of the native glycogen phosphorylase b from rabbit skeletal muscle and of the enzyme specifically deiminated by peptidylarginine deiminase have been studied. One arginine residue per phosphorylase b monomer is transformed into citrulline after 3 h of incubation with peptidylarginine deiminase. The maximal velocity of the enzymatic reaction for the modified phosphorylase b is 7-20% higher than that for the native enzyme. Deiminated phosphorylase b, like the native enzyme, shows a positive kinetic cooperativity with respect to glucose-1-phosphate. The affinity of the modified phosphorylase b for the allosteric activator AMP is one order of magnitude higher than that of the native enzyme. Deimination caused a pronounced reduction of the values of [I]0.5 for FMN and glucose, but the sensitivity of the deiminated enzyme to glucose-6-phosphate is much lower than that of the native phosphorylase b. Deiminated phosphorylase b, unlike the native enzyme, shows the positive cooperativity for FMN binding. Deiminated phosphorylase b, unlike the native enzyme, shows less capability to form tetramers in the presence of AMP as compared to the native enzyme.

Adenosine Monophosphate↗
PubMed1996

Establishment and characterization of a cytotrophoblast cell line from normal placenta of human origin.

A cell line has been established from human placentae at the first trimester of normal pregnancy. The cell line was obtained by culture of purified cytotrophoblast cells in serum-free medium supplemented with epidermal growth factor, insulin, dexamethasone and 0.1% bovine serum albumin. The cells can be subcultured for >30 passages in one to three splits. All the cells were mononuclear epithelial-like cells positive to cytokeratin 18, gonadotrophin-releasing hormone (GnRH), neuropeptide Y, neurotensin, leucine-enkephalin, dopamine and 5-hydroxytryptamine immunocytochemical staining. The cells secreted GnRH, progesterone and oestradiol (in the presence of testosterone) but little human chorionic gonadotrophin and no beta-endorphin. The cell line showed human karyotypes and had a population doubling time of 48 h in serum-free medium. However, the cells would stop growing in the medium containing fetal bovine serum. A normal cytotrophoblast cell line established in serum-free medium will be particularly useful in the study of cytotrophoblast cell proliferation and differentiation.

Animals↗
PubMed1996

[Effects of changes of plasma motilin level on the motility of gallbladder in patients with chronic renal failure].

In order to study the relationship between plasma motilin and motility of gallbladder in patients with chronic renal failure (CRF). Gallbladder volumes were determined with ultrasound in 17 normal subjects and 22 patients with CRF. Fasting gallbladder volumes (FGVs) and postprandial residual gallbladder volumes in patients with CRF were much smaller than those of normal subjects (P < 0.01, P < 0.01). There was no significant difference of maximal percentage emptying of gallbladder between normal subjects and patients with CRF (P > 0.05). In 17 normal subjects oral erythromycin administration reduce FGVs and postprandial residual gallbladder volumes (P < 0.05, P < 0.05). In 22 patients with CRF oral erythromycin administration changed neither FGVs nor postprandial residual gallbladder volumes. Radioimmunoassay was employed to measure plasma motilin concentration. The results showed that mean level of plasma motilin of patients with CRF was much higher than that of normal subjects (P < 0.01). There was sighificant negative correlation between plasma motilin level and FGVs. It is suggested that hypermotilinemia may be one of the major reasons for motility disorder of gallbladder in patients with CRF.

Adult↗
PubMed1996

[Experimental research on the distribution of insulin in condyle during mandibular functional protrusion in growing rats].

The purpose of this study is to evaluate insulin change in condylar cartilage during functional advancement of rat mandible by immunohistochemical technique (ABC method) in order to provide further information about the role of insulin in orthopedics and the relationship between insulin and proliferation of condylar cartilage. Staining gradient of insulin is observed in condylar cartilage, with the stain deepest in the geriminal layer, medial in the transitional, least in the maturational layer. The posterior region of condylar cartilage in the experimental groups is shown to have thickened significantly as compared with the control groups, especially the germinal layer. Stained-positive cells exhibit deeper stain and higher percentage. The stain in the other layers is also more obvious than that in the control groups. The results suggest: Insulin level in condyle changes with the different cartilage layers. Insulin distribution appears higher when condylar chondrocytes proliferate rapidly and lower when they differentiate actively. Functional orthopedics may stimulate the growth of condylar cartilage and raise the insulin level. The demonstrates that insulin correlates with hyperplasia of conylar chondrocytes.

Animals↗
PubMed1996

[Changes of superoxide dismutase and lipid peroxide in lung tissue of rats after intratracheal injection of crocidolite and benzo(a) pyrene].

Wistar rats were divided into 4 groups: control group, Cro group, B(a) p group and Cro plus B(a) p group. Samples of lung tissue were collected 90, 180, 270, 360 and 540 days after the third time of intratracheal. The superoxide dismutase (SOD) activity, the level of lipid peroxide (LPO) and the ratio of SOD/LPO were observed. The results indicated that there was a synergistic action of Cro. and B(a) p.

Animals↗
PubMed1996

[Chemical constituents of the roots of Bupleurum longicaule Wall. ex DC. var. franchetii de Boiss and B. chaishoui Shan et Sheh].

From the roots of Bupleurum longicaule var. franchetii, B. chaishoui and the official species B. chinense, ten saikosaponins have been isolated and identified as saikosaponin a, saikosaponin d, saikosaponin c, saikosaponin e, saikosaponin b2, 2"-O-acetylsaikosaponin a, 3"-O-acetylsaikosaponin a, 3"-O-acetylsaikosaponin d, 6"-O-acetylsaikosaponin a and 6"-O-acetylsaikosaponin d respectively. It has been shown that the chemical constituents of these three Bupleurum plants are very similar, therefore, the medicinal value of B. longicaule var. franchetii and B. chaishoui is further verified.

Apiaceae↗
PubMed1995

Enzymatic deimination of glycogen phosphorylase and a peptide of the phosphorylation site: identification of modification and roles in phosphorylation and activity.

The functional role of arginine residues in glycogen phosphorylase b was probed by enzymatic modification by using peptidylarginine deiminase, which converts arginine residues to citrulline. A peptide with sequence LysArgLysGlnIleSerValArgGlyLeu, corresponding to the phosphorylation site of serine-14 in phosphorylase, was a substrate for the deiminase. Although both arginine residues could be converted to citrulline, modification of arginine-16 occurred more rapidly than modification of arginine-10. Previous studies have implicated a role for arginine, notably arginine-16, in determining phosphorylase kinase activity with the peptide. Deimination altered the phosphorylation of the peptide. Monodeimination of the peptide at arginine-16 slowed down the phosphorylation reaction, but did not diminish the total amount of phosphorylation that could be obtained. Deimination of both arginines produced a peptide that could not be phosphorylated. Modification of phosphorylase b resulted in activation or inactivation of enzyme activity depending on the extent of reaction with peptidylarginine deiminase. A low level of deiminase causes inactivation initially, but after prolonged incubation activation occurs. With high level of deiminase only activation can be observed. Because changes in activity are seen only at subsaturating AMP concentrations (50-100 microM), inactivation and activation are likely due to changes in affinity of the enzyme for AMP. The protein modified with the high level of deiminase has multiple sites of deimination. Arginine 16 was established as a major site of modification. Only protein modified with the high level of deiminase showed modification of arginine-16 and effects on the phosphorylation of phosphorylation b. As with the modified peptide substrate, the reaction was slower with modified phosphorylase in comparison with native phosphorylase b. The results show the importance of the guanidino group of arginine-16 of the protein substrate in modulating the phosphorylase kinase reaction.

Amino Acid Sequence↗
PubMed1995

XIST expression is repressed when X inactivation is reversed in human placental cells: a model for study of XIST regulation.

Considerable evidence suggests that the X inactive transcript gene, XIST/Xist, has a role in the initial steps of X chromosome inactivation in the female mammalian embryo. It is transcribed exclusively from inactive X chromosomes, and its noncoding transcript seems to be essential for cis inactivation. Unexpected for a developmental gene, XIST continues to be expressed in adult somatic cells. To determine the effect of reversal of inactivation on the expression of XIST, we studied human X chromosomes that had been induced to reverse X inactivation by hybridization of chorionic villi cells from term placentas with mouse A9 cells. In nine hybrids with a reactivated X chromosome, XIST was either not expressed or expressed much less than the locus on the inactive X chromosome in the chorionic villi cells from which they were derived. The repressibility of XIST by reversal of inactivation in these placental cells mirrors events that occur during the ontogeny of oocytes and indicates that the locus is subject to regulation in somatic cells long after inactivation is established in the embryo. The small residual XIST activity from these active chromosomes suggests that low levels of XIST expression do not interfere with chromosome activity and raises the possibility that the induction of cis inactivation requires a certain level of XIST transcription. The chorionic villi hybrids provide an experimental system to study the developmental regulation of XIST.

Base Sequence↗
PubMed1995

Basic fibroblast growth factor reverses atherosclerotic impairment of human coronary angiogenesis-like responses in vitro.

The influence of atherosclerosis on vascular growth in humans was evaluated in an in vitro model of angiogenesis. Coronary artery intima-media explants from patients (n = 10) with coronary artery disease (CAD) (in all cases Stary type V lesions) and patients without CAD (n = 10) were cultured in a collagen matrix containing serum-free medium. Endothelial cell growth from explants was organized as capillary-like microtubes (CLM); the sum of their lengths was morphometrically quantitated as an index of angiogenesis. CLM growth was suppressed in CAD explants (n = 120), the index values at two weeks averaging only 20% +/- 3% of non-CAD explants (n = 120, P < 0.001). Addition of exogenous basic fibroblast growth factor (bFGF) (10 ng/ml) stimulated CLM growth substantially more in the CAD than in the non-CAD group, whereas bFGF-neutralizing antibodies nearly abolished growth in both. Endothelial cells isolated from non-CAD coronary arteries exhibited in culture typical endothelial characteristics, including cobblestone appearance, staining for von Willebrand factor, CLM formation on Matrigel substrate, and sensitivity to bFGF and to bFGF-neutralizing antibody. Inhibition of cell replication by oxidized low-density lipoprotein (OxLDL) was reversed by bFGF. We conclude that human atherosclerosis is associated with impairment of angiogenesis-like endothelial growth and that decreased bFGF availability contributes to the impairment.

Cell Count↗
PubMed1995

Microdialysis as a tool to measure dietary and regional effects on the complete profile of extracellular amino acids in the hypothalamus of rats.

Regional and dietary-induced changes in hypothalamic extracellular amino acid concentrations were examined. Microdialysis probes were simultaneously implanted in the hypothalamic paraventricular nucleus (PVN) and the lateral hypothalamus (LH) of anesthetized rats and perfused at a rate of 2 microliters/min. Dialysates were collected every 20 min for 1 h prior to gavage of a balanced amino acid mixture (0.85 g patterned after 1 g of chicken egg albumin) and then every 20 min for 3 h after treatment. Tail vein blood samples were also collected. Marked changes in plasma levels of most amino acids were evident immediately following the amino acid gavage. In the PVN, concentrations of isoleucine, leucine, methionine and valine all increased within 40 min, whereas significant decreases in glutamine, histidine and taurine were observed in the LH. In a separate study, PVN extracellular amino acid concentrations were examined in awake, freely-behaving rats following gavage of equicaloric loads of a balanced amino acid mixture, glucose (0.89 g) or water. Dialysate levels of glutamate, isoleucine, leucine, methionine, threonine, tyrosine and valine showed reliable increases after amino acid treatment, although the overall time course of these effects differed somewhat. The amino acid profile of the PVN was, in general, unaffected by glucose administration. These findings suggest that specific brain regions may respond uniquely to amino acid ingestion and further imply that dietary composition may influence the amino acid profiles of the extracellular fluid in brain.

Amino Acids↗
PubMed1995

Glycosidic aroma precursors of 2-phenylethyl and benzyl alcohols from Jasminum sambac flowers.

Benzyl 6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside (beta-primeveroside) (1), 2-phenylethyl beta-primeveroside (2), and 2-phenylethyl 6-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranoside (beta-rutinoside) (3) were isolated as aroma precursors of benzyl alcohol and 2-phenylethanol from flower buds of Jasminum sambac Ait. The isolation was guided by an enzymatic hydrolysis and GC and GC-MS analyses.

Benzyl Alcohol↗
PubMed1995

[Co-carcinogenic effect of crocidolite plus benzo(a)pyrene on the lungs of rats].

Epidemiological reports have indicated that occupational exposure to asbestos and smoking may greatly increase the incidence of lung carcinoma. In this study rats were injected intratracheally with crocidolite or benzo(a)pyrene [B(a)P] only, and crocidolite plus B(a)P in combination. The incidence of lung carcinomas in crocidolite group was 6.4% (3/47), in B(a)P group 10.4% (5/48) and crocidolite plus B(a)P group 46.3% (25/54). Besides, the survival curve and the mean survival time of rats with carcinoma dropped distinctly. Significant difference was shown among the crocidolite plus B(a)P group, crocidolite and B(a)P groups (P < 0.005). The result indicated the synergetic effect of crocidolite and B(a)P on the development of lung carcinoma in rats and the importance of giving up smoking in the people exposed to asbestos. A model of lung carcinoma in rat was successfully prepared for further study in experiment on treatment, prevention and mechanism.

Animals↗
PubMed1995

[Some biochemical indexes in white rabbit's blood affected by acute high intensity microwave].

Irradiation of white rabbits by 10, 50, 100 and 200 mW/cm2 microwave respectively can cause the disorder of protein metabolism, the abnormality of blood sugar, and the change of the activity of serum alpha-hydroxybutyrate dehydrogenase, lactate dehydrogenase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, acid phosphatase ect. These changes can be used as indexes in the evaluation of the effect of acute high intensity microwave exposure. The effect on the organism mainly depends on the intensity of exposure provided the dose of microwave remains the same.

Acid Phosphatase↗