PubMed Health⌕ Search

Biomedical subjects

Li Yuan

Publications and source records attributed to Li Yuan.

47 records · Page 3Linked to original sources
PubMed2002

The effect of Morinda officinalis How, a Chinese traditional medicinal plant, on the DRL 72-s schedule in rats and the forced swimming test in mice.

The present study observed the antidepressant-like action of the medicinal plant Morinda officinalis in the differential reinforcement of low rate 72-s (DRL 72-s) schedule, a behavioral screen selective and sensitive to antidepressant drugs, and the forced swimming test, a well-known animal model of depression. In the DRL 72-s schedule in rats, the plant extract (25-50 mg/kg), similar to clinically effective antidepressant drug desipramine (5-10 mg/kg), significantly reduced response rate and efficiency ratio while at the same time increasing reinforcement rate. In the forced swimming test in mice, the plant extract (50 mg/kg), like the effect of desipramine (20 mg/kg), also elicited a significant reduction in the duration of immobility. A tendency to this phenomenon could be seen at the dose of 100 mg/kg. Meanwhile, the plant extract, in the effective doses for the forced swimming test, had no effects on spontaneous motor activity in mice. These findings provide further support for the conclusion that M. officinalis extract possesses the antidepressant effect.

Animals↗
PubMed2002

Triplex operation for children with extrahepatic portal hypertension.

BACKGROUND/PURPOSE: How to deal with the vexatious problem of esophageal and gastric varices secondary to extrahepatic portal hypertension has been discussed extensively among pediatric surgeons around the world. The aim of this study is to evaluate the effect of triplex operation (splenopneumopexy, portal azygous devascularization, and ligation of splenic artery) for children with portal hypertension in the author's hospital. METHODS: From March 1993 to November 1998, 7 children with extrahepatic portal hypertension were admitted to the author's hospital to undergo triplex operation. The diagnoses of these patients were confirmed by gastroscopy, barium meal, and Doppler ultrasonography. The number of white blood cells and platelets and the hepatic function were checked before and after operation. And the free portal pressures (FPP) were checked before and after the ligation of the splenic artery. All patients underwent follow-up for 1 to 7 years (mean, 4.6 years). The episodes of upper gastrointestinal bleeding were recorded. The degree of varices of distal esophagus and proximal stomach were assessed by barium meal and gastroscopy. The diameters of the spleenic and portal vein were obtained by B ultrasonography. The portopulmonary shunt and portal blood flow were evaluated by color Doppler flow image (CDFI). The indices of hemorheology such as hematocrit, viscosity of whole blood and plasma, and the indexes of deformability and aggregability of red blood cells were obtained through viscometer (R-20 Seerle, Beijing, China). RESULTS: There was no operative mortality in this group. Postoperatively, hemorrhage from the esophagus and gastric varices was completely controlled. Although the diameter of spleen reduced progressively, no patient's spleen recovered to normal during the follow-up period. The degree of varices was mitigated, and the FPP was decreased significantly to 34.48 +/- 5.71 cm H(2)O from the preoperative 42.62 +/- 6.72 cm H(2)O (P <.05). The rate of portal flow also was decreased. The direction of portal vein was bidirection (one part was away from the liver and the other was toward the liver). The numbers of white blood cells and platelets were increased. The viscosities of whole blood and hematocrit also were increased after operation. CONCLUSION: The triplex operation is an effective procedure for the control of hemorrhage from varices in children with extrahepatic portal hypertension.

Azygos Vein↗
PubMed2002

Immediate-early Fos protein levels in brainstem neurons of male and female gonadectomized mice subjected to cold exposure.

The expression of the immediate early gene c-fos has been used extensively as a marker for neural activation in response to acute and chronic stressful stimuli in brain and spinal cord. The present study examined the expression of Fos protein in the brainstem nuclei of male and female gonadectomized mice in response to cold stress. Free-floating sections were processed immunohistochemically for Fos protein using standard avidin-biotin complex methods. The number of Fos-positive neurons in each nucleus was determined. Although the experiment was designed to look for gender differences, results were equivalent between females and males. After mice were exposed to a cold ambient temperature (4 degrees C) for 2 h, elevated numbers of Fos-positive neurons were counted in the medullary gigantocellular reticular nucleus, medullary raphe nucleus, nucleus of the solitary tract and in locus coeruleus. However, no elevated expression was found in nucleus ambiguus, nor in neurons of the A1 group, nor the C2 or C3 group. Similar to rats, these results with mice reveal a widespread arousal system in the lower brainstem activated by cold stress in both genders. These findings in gonadectomized mice have set the stage for investigations following hormonal and genetic manipulations.

Animals↗
PubMed2002

Vasculogenesis and the search for the hemangioblast.

Embryonic endothelial cells (EC) are generated by two mechanisms, vasculogenesis and angiogenesis (1). The term vasculogenesis describes the de novo emergence of EC progenitors from the mesoderm, whereas angiogenesis corresponds to the generation of EC by sprouting from the pre-existing vascular network. Until recently, it was thought that vasculogenesis was restricted to the period of embryonic development, whereas in the adult, only angiogenesis contributed to EC proliferation. The discovery of circulating EC progenitors in adult bone marrow and peripheral blood has suggested that additional mechanisms besides angiogenesis can occur in the adult, and therefore have renewed interest in the embryonic origin and the development of these progenitor cells. Vasculogenesis in the chick embryo has been studied since the beginning of the 20th century. During early development, vasculogenesis is intimately linked to the emergence of hematopoietic cells (HC). The existence of a common precursor for both EC and HC, termed "hemangioblast," was postulated (2). The purpose of this review is to summarize the experimental evidence concerning the emergence of EC and HC during embryonic life.

Adult↗
PubMed2002

Abnormal lymphatic vessel development in neuropilin 2 mutant mice.

Neuropilin 2 is a receptor for class III semaphorins and for certain members of the vascular endothelial growth factor family. Targeted inactivation of the neuropilin 2 gene (Nrp2) has previously shown its role in neural development. We report that neuropilin 2 expression in the vascular system is restricted to veins and lymphatic vessels. Homozygous Nrp2 mutants show absence or severe reduction of small lymphatic vessels and capillaries during development. This correlated with a reduction of DNA synthesis in the lymphatic endothelial cells of the mutants. Arteries, veins and larger, collecting lymphatic vessels developed normally, suggesting that neuropilin 2 is selectively required for the formation of small lymphatic vessels and capillaries.

Animals↗
PubMed2002

Reversed flow injection spectrophotometric determination of low residuals of chlorine dioxide in water using chlorophenol red.

A novel, simple, rapid, sensitive and highly selective flow injection procedure for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz, free chlorine, chlorite, chlorate and hypochlorite, is developed. The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct spectrophotometric determination for chlorine dioxide owing to the serious interference of free and combined chlorine. The procedure gave a linear calibration graph over the range 0-0.71 mg/L of chlorine dioxide. With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.

Chlorine Compounds↗
PubMed2002

[Effect of metformin on gene expression of phosphoenolpyruvate carboxykinase].

OBJECTIVE: To investigate the effect and mechanism of antihyperglycemic agent metformin on the gene expression of phosphoenolpyruvate carboxykinase (PEPCK)-a key enzyme within the regulation of gluconeogenesis in hepatocytes and to determine whether the effects of metformin on hepatocytes are transmitted throughout the known insulin signaling pathways. METHODS: Confluent H4IIE rat heptoma cells were cultured with metformin 0.1 mmol/L for 16 h and then stimulated with various agents: insulin, cyclic adenosine monophosphate (cAMP), dexamethasone, signaling transduction inhibitor wortmannin and UO126. The gene expression of PEPCK was examined by Northern blot analysis. RESULTS: Metformin significantly decreased basal PEPCK mRNA levels by 75% (P < 0.01). Incubation with metformin alone had no significant effect on cAMP/dexamethasone stimulated PEPCK gene expression. In contrast, insulin 0.1 nmol/L significantly inhibited cAMP/dexamethasone stimulated PEPCK gene expression by 67% (P < 0.01), when insulin 0.1 nmol/L was present together with metformin, cAMP/dexamethasone induced PEPCK gene expression was decreased by 94% (P < 0.01). Both insulin signaling pathway inhibitors, phosphatidyl-inositol-3-kinase (PI3K) inhibitor wortmannin and mitogen-activated protein kinase (MAPK) inhibitor UO126, had no significant effect on inhibited PEPCK mRNA expression by metformin, but wortmannin blocked significantly inhibitory regulation of insulin on PEPCK gene expression (P < 0.01). CONCLUSION: Metformin can inhibit the PEPCK gene expression via either an insulin-independent or interaction with insulin manner. The inhibitory effects of insulin on PEPCK gene expression are mediated through PI3K pathway, not MAPK pathway.

Animals↗
PubMed2002

Inhibition of phosphoenolpyruvate carboxykinase gene expression by metformin in cultured hepatocytes.

OBJECTIVE: To investigate the effect and mechanism of the antihyperglycemic agent metformin on the expression of phosphoenolpyruvate carboxykinase (PEPCK) gene in hepatocytes and to determine whether the effects of metformin in hepatocytes are transmitted throughout the known insulin signaling pathways. METHODS: Confluent H4IIE rat heptoma cells were cultured for 16 h with 0.1 mmol/L metformin either in absence or presence of 0.1 nmol/L insulin, and then stimulated with various agents. The expression of PEPCK gene was examined by Northern blot analysis. RESULTS: Therapeutic concentrations of metformin significantly inhibited basal PEPCK mRNA expression and also decreased cAMP and dexamethasone induced PEPCK gene expression through interaction with insulin. In the presence of insulin signaling pathway inhibitors wortmannin and UO126, metformin reduced PEPCK mRNA levels, but wortmannin blocked inhibitory regulation of insulin on PEPCK gene expression. CONCLUSION: Metformin inhibits PEPCK gene expression via either an insulin-independent or an interacting-with-insulin manner. The results suggest that a possible mechanism by which metformin reduces gluconeogenesis could be associated with the inhibition of PEPCK gene expression.

Androstadienes↗
PubMed2002

[Determination of trace tin in food by solid-phase spectrophotometry].

A new method for the determination of trace amounts of tin by resin-phase spectrophotometry has been developed and the detailed experimental conditions investigated. Tin ion reacts with procatechol violet(PV) in potassium hydrogen phthalate-HCl buffer media(pH2.5) to form a stable complex. The complex enriched on an anion-exchange resin has a maximum absorption wavelength of 570 nm. The absorbance is directly proportional to the concentration of tin in the region of 0-150 micrograms.L-1 with an apparent molar absorptivity of 7.2 x 10(6) L.moL-1.cm-1. Most of the co-existed metal ions do not interfere the determination of tin ion. The developed procedure has been successfully employed to the determination of tin in some food examples.

Animals↗
PubMedDate not supplied

Real-time 3-dimensional echocardiography: a review of the development of the technology and its clinical application.

Real-time 3-dimensional echocardiography (RT3DE) is a new imaging technique that can provide accurate, important, and additional information concerning cardiovascular morphology, pathology, and function. This article will review the development of the technology of RT3DE and its clinical application. As the technique continues to evolve, RT3DE is bound to play an increasingly important role in the diagnosis, prognosis, and treatment of patients with various forms of cardiovascular disease.

Echocardiography, Three-Dimensional↗