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Biomedical subjects

S Yuan

Publications and source records attributed to S Yuan.

At least 127 records · Page 7Linked to original sources
PubMed1996

Effect of extended parietal cell vagotomy on long-term nutrition and digestive function.

OBJECTIVE: To study the effect of extended parietal cell vagotomy (EPCV) on long-term nutritional status and digestive-absorption function. PATIENTS AND METHODS: Thirty-six patients undergoing EPCV were compared with 30 patients with subtotal gastrectomy (SG) 7-14 years after operation. The patients were evaluated in terms of nutritional status, gastric secretion, gastrointestinal motility, and intestinal digestive-absorption function. RESULTS: The nutritional status was generally less satisfactory in 33.3% patients with anemia after SG and body weight decreased in 54%. The patients after EPCV were all in good nutritional status, and had no symptoms of anemia; 56% of them had body weight increased by more than 3 kg. The mean basal acid output (BAO), maximal acid output (MAO), and peak acid output (PAO) of the EPCV group were significantly reduced after operation (P < 0.01), and moderately reduced as compared with those of the control group (P > 0.05). But the BAO, MAO, and PAO of the SG group were more markedly reduced than those of the control group (P < 0.001) before operation. Vitamin B12, folacin, intrinsic factor and iron protein level of serum in the EPCV group were slightly decreased as compared with those of the control group (P > 0.05), but more significantly decreased in the SG group than in the control group (P < 0.001). Iron protein and intrinsic factor level was lower than the normal level. The gastric emptying time and small intestinal passthrough time of EPCV were more close to the normal physiological status, but in the SG group, they were significantly fast (P < 0.001). The results of intestinal D-xylose absorption test in EPCV and SG groups were similar (P > 0.05). CONCLUSIONS: EPCV is capable of preserving gastric acid of physiologic level and normal digestion-absorption function. The effect of EPCV on long-term nutrition and digestion absorption function was extremely milder than that of SG. Therefore, a theoretical basis is provided for the rationality of EPCV.

Adult↗
PubMed1996

[A preliminary study of the anti-cancer effect of tanshinone on hepatic carcinoma and its mechanism of action in mice].

In this paper is reported the study of the anti-cancer effect of Tanshinone and its mechanism of action in vivo. The proliferating kinetics of hepatic carcinoma H22 cells was measured in mice by in vivo bromodeoxyuridine (Brdu) labeling and immunohistochemical staining of the proliferating cell nuclear antigen (PCNA). The tumor inhibitory rates of Tanshinone were 50.0%, 38.5% and 40.6% in 3 experiments, respectively. Compared with those of the DMSO-treated control groups, the differences were statistically significant (P < 0.01). The Brdu labeling and PCNA positive cells were 51.8 +/- 7.9 and 451.1 +/- 26.1 respectively, which were significantly lower than those of the controls (84.4 +/- 24.3, 694.8 +/- 117.1) (P < 0.01). The results once more confirm that tanshinone has anti-cancer activity and suggest that the mechanism of action might be associated with inhibition of DNA synthesis, PCNA expression and DNA polymerase activity of tumor cells.

Abietanes↗
PubMed1996

[An observation of the effect of tanshinone on cancer cell proliferation by Brdu and PCNA labeling].

The aim of this study was to find out the anti-cancer activity of Tanshinone and its mechanism of action. Human hepatic carcinoma cell line (SMMC-7721) and leukemia cell line (HL60) were treated with tanshinone the cancer cell proliferation indices were measured by Brdu Labeling and immuno-histochemical stain of PCNA. The Brdu labeling rates of human hepatic carcinoma and leukemia cells treated with tanshinone were 8.95% and 19.01%, which were lower than those of controls (28.0%, 25.57%) respectively (P < 0.01), PCNA positive rates were 57.0% and 30.32%, which were significantly lower than those of controls (74.3%, 47.05%) (P < 0.01). The results indicate that Brdu labeling and PCNA detection may have important utility in the studies of tumor cell proliferation and the relative factors affecting the cell proliferation. The inhibitory effect of tanshinone on cancer cell proliferation might be associated with inhibiting DNA synthesis, PCNA expression and activity of DNA polymerase delta of the tumor cells.

Abietanes↗
PubMed1996

[HPLC analysis of mimic vinegar-processed yuanhuacine].

In this paper, the variation of yuanhuacine samples after vinegar-processing and hydrolysis has been analyzed by HPLC. The result has shown that the content of yuanhuacine decreases hearly 22% after mimic vinegar-processing. Also this procedure has brought a new compound-hydrolytic product of yuanhuacine, whose UV lambda max is 264nm. The research work is to be continued.

Acetic Acid↗
PubMed1996

[Separation and preparation of indole alkaloids in Lycorma delicatula White. by HPLC].

A HPLC method for separating and preparing indole alkaloids is described. HPLC conditions for analysis: BIO-RAD series 700 HPLC, model 700 data station, UV: model 1749 UV-VIS monitor, column: BIO-RAD Hi-pore RP318, 250 mm x 10 mm, mobile phase: 80% methanol-H2O(gradient), flow rate: 1.5 ml/min, detection wavelength: 254 nm. On the basis of spectral (1HNMR, 13CNMR, H-H COSY, MS, DEPT) and chemical evidence, the structures of two compounds were elucidated as beta-yohimbine (yohimban-16-carboxylic acid-17-hydroxy methylester (3 alpha, 16 alpha, 17 beta)) and ajmalicine (oxayohimban-16-carboxylic acid-16,17-didehydro-19-ethyl methyl ester (19 alpha)).

Animals↗
PubMed1996

[HPLC analysis of the influence of processing on the contents of genkwanin in flos Genkwa].

The contents of genkwanin in differently processed samples of Flos Genkwa have been analyzed by HPLC. The result shows that the contents in all these samples are decreased, the least decreased being the one processed with vinegar. The contents of genkwanin in samples of Flos Genkwa from the main habitats of china have also been analyzed by HPLC. Experimental criteria are provided for the quality control of Flos Genkwa.

Chromatography, High Pressure Liquid↗
PubMed1996

[Protective effect of active components extracted from radix Astragali on human erythrocyte membrane damages caused by reactive oxygen species].

A study has been made on the protective activities of active components extracted from Radix Astragali by using reactive oxygen species initiated lipid peroxidation of purified human erythrocyte membrane. The results show that the total flavonoids of Astragalus and total saponins of Astragalus can significantly inhibit the membrane lipid peroxidation generated by O2.-, H2O2 and UV rays, while the total polysaccharide of Astragalus possesses weaker protective activity.

Drugs, Chinese Herbal↗
PubMed1996

[HPLC analysis of mimic vinegar-processing of genkwanin].

In this paper, the variation of genkwanin content before and after mimic vinegar-processing has been analyzed by HPLC. The result has shown that there is no difference between the quantity and quality of genkwanin before and after mimic vinegar-processing. It is clarified that acetic acid is not the main reason for the decrease of genkwanin content in the flower of Daphne genkwa during the process of vinegar-fry.

Acetic Acid↗
PubMed1995

Identification and characterization of human beta 2-chimaerin: association with malignant transformation in astrocytoma.

Molecular processes resulting in the malignant transformation from low- to high-grade astrocytoma remain poorly understood. Using reverse transcriptase PCR, we identified a gene that is differentially expressed in normal brain and low-grade astrocytoma compared to glioblastoma tissues. This gene is identical to human beta 2-chimaerin, which encodes a 468-amino acid GTPase-activating protein for p21rac. The gene was localized to human chromosome 7p15.3 by fluorescence in situ hybridization mapping. Human beta 2-chimaerin is expressed in a variety of human tissues, with the highest expression level detected in human brain and pancreas. RNase protection assays indicated that the expression level of this gene is high in all the normal brain and low-grade astrocytoma samples tested compared to malignant gliomas. The down-regulation of beta 2-chimaerin expression in the high-grade gliomas suggests that decreased expression of this gene may be a feature of progression in the development of malignant glioma.

Amino Acid Sequence↗
PubMed1995

Mesodermal patterning during avian gastrulation and neurulation: experimental induction of notochord from non-notochordal precursor cells.

The cells that are normally fated to form notochord occupy a region at the rostral tip of the primitive streak at late gastrula/early neurula stages of avian and mammalian development. If these cells are surgically removed from avian embryos in culture, a notochord will nonetheless form in the majority of cases. The origin of this reconstituted notochord previously had not been investigated and was the objective of this study. Chick embryos at late gastrulal early neurula stages were cultured, and the rostral tip of the primitive streak including Hensen's node was removed and replaced with non-node cells from quail epiblast to ensure that the cells normally fated to be notochord would be absent and that healing of the blastoderm would occur. Embryos were allowed to develop for 24 hr, and the presence and origin (host or graft) of the notochord were assessed using antibodies against notochord or quail cells. Two notochords typically developed; both were almost exclusively of host origin. The primitive streak, and in some cases adjacent tissues, was removed from another group of embryos in an attempt to estimate the mediolateral position and extent of the cells required to form reconstituted notochord. Additional experimental embryos with and without grafts were transected at various rostrocaudal levels in an attempt to estimate the rostrocaudal extent of the cells required to form reconstituted notochord. Finally, various levels of the primitive streak either were placed in a neutral environment (the germ cell crescent) or were grafted in place of the node. Collective results from all experiments indicate that the areas lateral to the rostral portion of the primitive streak, estimated to have a rostrocaudal span of less than 500 microns and a mediolateral extent of less than 250 microns, are critical for formation of the reconstituted notochord. Fate mapping and histological examination of this region identify 4 possible precursor cell populations. Further studies are underway to determine which of the 4 possible precursor cell types forms or induces the reconstituted notochord, and which tissue interactions underlie this change in cell fate.

Animals↗
PubMed1995

Immobilization of heparin oligosaccharides onto radiofrequency plasma modified pyrolytic carbon-coated graphite.

Heparin oligosaccharides with different anticoagulant activities were prepared and immobilized onto pyrolytic carbon coated graphite (PC) heart valve materials commonly used in mechanical heart valve prostheses. Prior to immobilization, PC surfaces were modified by radiofrequency plasma polymerized N-vinyl-2-pyrrolidone (PPNVP) thin films (approximately 100 nm) and derivatized to provide surface hydroxyl groups. Cleaved, low affinity heparin (C-heparin) with factor Xa inhibition activity of 107 to 130 IU/mg, was prepared by partial deaminative cleavage of commercial crude heparin, and high-affinity heparin (HA-heparin) with factor Xa inhibition activity of 550 to 1000 IU/mg was prepared by fractionation of C-heparin using agarose-ATIII affinity chromatography. C-heparin and HA-heparin were immobilized to surface modified PC by reductive amination. Anticoagulant activity of the heparin immobilized surfaces was determined by chromogenic assay for the inhibition of factor Xa. Highest surface anticoagulant activity was measured on C-heparin immobilized surfaces (64.0 +/- 7.3 mIU/cm2) compared with HA-heparin immobilized surfaces (27.2 +/- 12.2 mIU/cm2), suggesting higher binding of C-heparin than HA-heparin on the modified PC surfaces. Immobilized surfaces were evaluated under dynamic flow conditions, by subjecting samples to shear stress of up to 206 dyn/cm2 in the presence of 5% albumin solution or human plasma. Anticoagulant activity of the immobilized heparin was retained, although reduced, and the modified surfaces showed evidence for protein resistance.

Anticoagulants↗
PubMed1995

Identification of inducing, responding, and suppressing regions in an experimental model of notochord formation in avian embryos.

The notochord normally arises from committed cells in the rostral tip of the primitive streak. After removal of these cells from the avian gastrula, embryos with notochords nevertheless develop in the majority of cases. A region required for the formation of this reconstituted notochord lies lateral to the primitive streak. In the present study we have determined that this region acts as an inducer for more lateral cells in the epiblast, which actually give rise to the reconstituted notochord. The strongest inducing region lies between 0-250 micrometer lateral to the streak and 500-750 micrometer caudal to the rostral end of the streak and chiefly contains cells normally fated to form lateral plate and somitic mesoderm. The responding region is located 250-500 micrometer lateral to the streak and 0-750 micrometer caudal to the rostral end of the streak. This area chiefly contains cells normally fated to form neural ectoderm, although cells normally fated to form lateral plate and somitic mesoderm are also within this area. The inducing and responding areas interact to form reconstituted notochord either when the primitive streak, including its rostral end (Hensen's node), is removed from the cultured blastoderm or when the inducer and responder are grafted together into an ectopic site. Grafting Hensen's node into isolates containing both inducer and responder blocks formation of reconstituted notochord, suggesting that Hensen's node suppresses formation of lateral notochords during normal development. These findings increase our understanding of the early interactions between mesoderm and ectoderm and provide a novel model system that is well defined and accessible for studying inductive events in higher vertebrates.

Animals↗
PubMed1995

Experimental analyses of the rearrangement of ectodermal cells during gastrulation and neurulation in avian embryos.

The rearrangement of ectodermal cells was studied in chimeras in which grafts were transplanted during late gastrula and early neurula stages to heterotopic locations in avian embryos. Three types of experiments were done. In all experiments, Hensen's node was extirpated completely and replaced with an epithelial plug derived from 1 of 3 regions of the prospective ectoderm. In type-1 experiments, Hensen's node was replaced with a plug consisting of precursor cells of the floor plate of the neural tube. In type-2 experiments, Hensen's node was replaced with a plug consisting of precursor cells of the lateral wall of the neural tube. In type-3 experiments, Hensen's node was replaced with a plug consisting of precursor cells of the epidermal ectoderm. In all experiments, the amount and direction of cell rearrangement that occurred in the transplanted ectodermal plug was essentially typical for prospective ectodermal cells normally residing within Hensen's node. That is, transplanted ectodermal cells underwent lateral-to-medial cell-cell intercalation and contributed to the ventral midline of the neural tube along its entire rostrocaudal extent. In most embryos, a notochord was reconstituted from host cells, despite the fact that Hensen's node--the prime source of prospective notochordal cells in intact embryos--was extirpated completely; however, a few embryos had long notochordal gaps. In such essentially notochordless embryos, the ventral midline of the neural tube still derived from grafted cells, but it failed to form a floor plate, providing further confirmation of the results of several previous studies that the notochord is required to induce the floor plate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Multiple cis-elements mediate shear stress-induced gene expression.

Fluid shear stress activates the expression of immediate early (IE) genes in vascular endothelial cells. The transcriptional regulation can be mediated through the shear stress-sensitive cis-acting elements at the 5' promoter regions of various IE genes such as the monocyte chemotactic protein-1 (MCP-1) gene. We linked wild-type and mutated MCP-1 promoters to the reporter gene luciferase and used such constructs to investigate the role of the phorbol ester TPA responsive element (TRE) in the shear-induced MCP-1 gene expression in vascular endothelial cells. Functional analysis showed that TGACTCC (a divergent TRE) located at nt -54 to -60 is necessary for shear-inducibility in bovine aortic endothelial cells (BAEC). The induction of the wild-type MCP-1 promoter construct by shear stress was attenuated by pretreating the cells with 1 microM dexamethasone or 1 microM retinoic acid 12 h before the shear stress experiments. The induction by shear stress reduced from 13-fold in the untreated cells to 7- and 3-folds in the dexamethasone- and retinoic acid-treated cells, respectively. These results demonstrate that the glucocorticoid receptor and retinoic acid receptor may interfere with the shear stress-activated AP-1/TRE. The reporter activity of HIV(LTR), which is a plasmid construct of the long terminal repeats of the human immunodeficiency virus and contains a kappa B enhancer element, was also activated by shear stress. The results of our investigations indicate that the shear stress-induced IE gene expression can be mediated through multiple cis-elements.

Animals↗
PubMed1995

The dispersion of repolarization in patients with ventricular tachycardia. A study using simultaneous monophasic action potential recordings from two sites in the right ventricle.

The role of increased dispersion of repolarization in the genesis of torsade de pointes and ventricular fibrillation has been well recognized generally, but not in the genesis of monomorphic ventricular tachycardia (VT). Monophasic action potentials (MAP) were therefore recorded simultaneously from the right ventricular (RV) apex (RVA) and outflow tract (RVOT) during sinus rhythm, RV pacing and programmed extra stimulation (PES) in 24 patients with VT. The activation time (AT), MAP duration at 90% repolarization (MAPd), and repolarization time (RT) were measured and their dispersions, defined as the differences in these parameters between RVA and RVOT, were calculated. During sinus rhythm and RV pacing, the dispersions of AT, MAPd and RT (dispersions) were significantly larger in the 17 patients with a VT induced than in those without. During PES, the dispersions were further augmented in the S2 beats in the seven patients with a sustained VT induced, the maximal dispersion of RT being 85 +/- 22 ms. Both the dispersion of AT and that of MAPd contributed to the dispersion of RT. In both of our two patients with a sustained VT induced during MAP recording, a marked increase in dispersions of RT (140 and 190 ms, respectively) was observed immediately before the initiation of the VT. A link between the dispersions and the inducibility of a monomorphic VT was found in our patients, which suggests that the increased dispersions play an important role in the genesis of a monomorphic VT.

Action Potentials↗
PubMed1995

A new method to localize brain nuclei for surgery in extrapyramidal disease.

A CT localization method to be used with the Leksell stereotactic system was employed to locate the ventral lateral nucleus of the thalamus (VL) and globus pallidus (GP) for treating extrapyramidal disease (EPD). The study comprised 100 normal adults and 70 cases of EPD, and results in both populations were compared. The 70 cases of EPD were studied ventriculography, and 30 normal adults were studied my MRI. Results indicate the accuracy of localization of the primary targets was 94.25% with the CT localization method described herein and 88.9% in the control group. In conclusion, the new CT localization method is a valuable technique to locate brain nuclei and to replace ventriculography with stereotactic surgery in the treatment of EPD patients.

Adolescent↗
PubMed1995

[Quantitative determination of genkwanin in flos Genkwa by TLC-densitometry].

The contents of genkwanin in Flos Genkwa processed in different ways were determined by TLC-densitometry. The result showed that the contents of genkwanin in different samples were 0.128%-0.389% and the rate of recovery was 98.8%, thus offering a reference to the selection of top processing technology.

Chromatography, Thin Layer↗