Biomedical subjects

X F Wang

Publications and source records attributed to X F Wang.

At least 127 records · Page 7Linked to original sources

PubMed1994

[A study of prostaglandine E(2) level in root canal fluid of patients with periapical lesions]

It has been reported that there is close relationship between prostaglandine E(PGE) and the pathogenesis of periapical lesions, In this study the root canal fluid(RCF) of 35 cases with acute,chronic and convalescent periradicular lesions were collected with assessed by the method of radioimmunoassay.The results showed:RCF-PGE(2) levels were increased with the severity of periapical lesion(P<0.01).The PGE level was highest in acute periradicular lesions,middle in chronic,and lowest in convalescent.RCF-PGE(2) levels were significantly different between either two groups of the three groups of patients(P<0.01-0.05).This study repeatedly proved that PGE(2) has certain effect in pathogenesis of periapical lesions and it is meaningful in guiding clinical therapy.It was also pointed out that RCF is one of worthwhile samples in the study of periradicular lesion.

Journal Article↗

PubMed1994

[Clinical efficacy of ciprofloxacin and ofloxacin].

The clinical efficacy, antibacterial activity and adverse effects of ciprofloxacin (CPLX) and ofloxacin (OFLX) produced in our country were compared in five clinical hospital in Beijing and Guangzhou in 1992. Two groups, each consisting of 100 cases, were treated with CPLX and OFLX respectively. The total cure rate was 79% and effective rate 94% after one course of treatment. There was no difference between the two groups (P > 0.05). The positive rate of presence of pathogens was 95% in both groups, but the rate of transformation from positive to negative after one course of treatment was 95.8% (OFLX) and 87.4% (CPLX) respectively. The difference between the two groups was significant (P < 0.05). 99 and 96 strains of bacteria were detected in the CPLX and OFLX group respectively; the elimination rate was 87.9% and 95.8% (P < 0.05). Incidence of adverse effects was 12% (OFLX) and 21% (CPLX) respectively. In a word, both drugs are effective in treating bacterial infections of digestive system, urinary system and respiratory tract. They are safe and reliable. OFLX is better than CPLX in bacteria elimination and incidence of adverse effects.

Adolescent↗

PubMed1994

[Effects of NG-nitro-L-arginine and reduced hemoglobin on endothelium-dependent relaxation of mesenteric artery in SHRsp].

It was verified in our previous study that endothelium-dependent relaxation (EDR) in the mesenteric artery strip of adult spontaneously hypertensive rats (SHR and SHRsp) was decreased upon addition of acetylcholine (ACh). In order to explore further the mechanism of this decrease of EDR, the effects of NG-nitro-L-arginine (L-NNA) (a NO synthase inhibitor) and reduced hemoglobin (RHb) (a scavenger of EDRF) on this ACh EDR were investigated in both stroke-prone SHR (SHRsp) and control WKYs. Our results showed that the difference of EDR (ACh 10(-8)-10(-5) mol/L) between SHRsp and WKY disappeared in the presence of L-NNA (10(-3) mol/L), but addition of RHb (10(-5) mol/L) would abolish such a difference only at ACh 10(-7)-10(-8) mol/L. In comparison to changes of EDR (ACh 10(-8)-10(-5) mol/L) between post L-NNA and post RHb in WKY and in SHRsp, no significant difference was found in WKY, but significant difference was found in SHRsp. And also, it appeared that the sensitivity of intact endothelium mesenteric artery of SHRsp to RHb was similar to WKY, but that to L-NNA is lower than that of WKY. Consequently it is considered that in the attenuation of EDR in hypertensive visceral vessels, the EDRF mechanism and endothelial L-arg-NO pathway are not identical.

Animals↗

PubMed1993

Determination of most appropriate Nyquist velocity for applying hemispherical flow convergence equation to calculate flow rate using the transorifice pressure gradient: digital computer analysis of Doppler color flow convergence region.

Nyquist velocity and transorifice pressure gradient dramatically influence color aliasing shape and accuracy of simple hemispherical flow convergence equation for calculation of flow rate. The present in vitro study was performed to determine whether the value of Nyquist velocity, at which the shape of proximal isovelocity surface is best fit for a given shape assumption in different orifice size, and the flow rate may be a determinable and orifice size independent function of clinically measurable peak velocity or transorifice pressure gradient. Steady flow was driven through circular discrete orifices with diameter of 3.8 mm, 5.5 mm and 10 mm and flow rate ranging from 2.88 L/min to 8.28 L/min. For every flow rate, Doppler color encoded M-mode images through the center of flow convergence region were transferred into the microcomputer in their original digital format. The continuous wave Doppler traces of maximal velocity through the orifice were performed for the calculation of pressure gradient. Direct numerical spatial velocity measure using color pixel intensity was obtained from the transferred color encoded M-mode images with computer software. The shape of isovelocity surface was determined by the ratio of calculated flow rate with hemispherical flow convergence equation to the actual flow rate. Both the flow rate and orifice size influence the position of the velocity profile curve. The shape of isovelocity surface is not constant and changes with the velocities used for the calculation of flow rates for a given flow rate and orifice size or pressure gradient and also changes with the flow rate or transorifice pressure gradients for a constant Nyquist velocity and orifice size.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗

PubMed1993

Visualization of patent foramen ovale by biplanar transesophageal echocardiography.

It is difficult for conventional transthoracic echocardiography (TTE), by which precise and accurate images of interatrial septum (IAS) can not be acquired, to diagnose patent foramen ovale (PFO) clearly. To evaluate the diagnostic value of biplanar transesophageal echocardiography (TEE) for PFO, TTE and biplanar TEE were performed simultaneously in 270 patients. It was found that in 7 patients patent foramen ovale was detected only through longitudinal planes of biplanar TEE. IAS, which consists of primitive septum and membrane of fossa ovalis, can be directly visualized by two-dimensional images of TEE; in patients with PFO, a dull color flow, which shunts from the right atria to the left atria through the gap between primitive septum and fossa ovalis, can be detected by color Doppler flow images. Furthermore, some right-to-left shunting microbubbles through the valve of patent fossa ovalis can be discovered by cardiac acoustic contrast echocardiography. In conclusion, biplanar TEE combined with color Doppler image and cardiac acoustic contrast facilitates a definite diagnosis of patent foramen ovale as the excellent anatomic images of IAS can be obtained from multiple views under this kind of performance.

Adult↗

PubMed1993

Effect of platelet activating factor antagonist WEB 2086 on the production of TNF from murine peritoneal macrophages.

In the present study the effect of platelet activating factor (PAF) antagonist WEB 2086 on the production of tumor necrosis factor (TNF) from primed murine peritoneal macrophages was investigated. At 10(-6) and 10(-5) mol/L, WEB 2086 was found to significantly inhibit LPS induced TNF production from macrophages by activated thioglycollate solution. WEB 2086 inhibition of TNF release began 4 h after LPS stimulation and lasted 22 h with a peek at 16 h. The results showed that PAF might play an important role in the production of TNF. Four methods were compared in the bioassay of TNF. The data demonstrated that L-929 cells treated with actinomycin D and sodium fluoride were the most sensitive for the assay of TNF. This method was employed in this study.

Animals↗

PubMed1993

Influence of airway inflammatory changes on airway hyperresponsiveness in asthmatics.

The effect of changes of airway inflammation on airway nonspecific reactivity were studied in 29 patients with chronic asthma. Detailed examinations of bronchial lavage (BAL) fluid and airway responses to histamine, propranolol and exercise were performed before and after treatment. The patients treated with steroids had significant improvements in parameters of BAL fluid cells and mediators with consistent changes of decreasing airway reactivities to propranolol and exercise after treatment. Whereas no significant changes occurred in the patients treated with B2-agonist either in inflammatory parameters or airway responses. On the other hand, airway response to histamine changed little in all asthmatic patients. Our study implied that inhibiting the airway inflammation in asthmatics may lead to marked decrease of airway response to non-mediator stimuli but fail to attenuate bronchial hyperresponse to mediator stimuli like histamine.

Adult↗

PubMed1993

[Studies on the chemical constituents of Ventilago leiocarpa Benth].

Three anthraquinones (1-3) and two naphthoquinones(4,5) were isolated from the root of Ventilago leiocarpa Benth (Rhamnaceae). On the basis of spectroscopic data and X-ray diffraction analysis compound 5, ventilagolin, was shown to be a new naphthoquinone occurring as a racemate.

Drugs, Chinese Herbal↗

PubMed1993

[Cardioprotection of 2-[p-(dimethylamino)styryl]pyridine methiodide against ischemic damage and myocardial lipid peroxidation].

Mice were injected ip DSPM 1 or 3 mg.kg-1 3 h prior to a subcutaneous injection of isoproterenol (Iso) 20 mg.kg-1 once daily for 2 d. Iso induced reductions of Se-glutathione peroxidase (Se-GSH-PX), superoxide dismutase (SOD) activities, and an increase of malondialdehyde (MDA) content in myocardium. DSPM 1 or 3 mg.kg-1 significantly abated reduction of Se-GSH-PX activity and decreased MDA production and DSPM 3 mg.kg-1 also abated reduction of SOD activity in the hearts from Iso-treated mice. The changes of above indices were in accordance with those of myocardial ultrastructure and creatine phosphokinase (CPK) concentration in serum. The results indicate that DSPM has a protective effect on myocardial ischemic injury probably by inhibiting oxygen free radicals and subsequent lipid peroxidation.

Animals↗

PubMed1993

[Alpha-adrenoceptor stimulation mediated positive chronotropic effect in isolated right heart atria of normotensive and SHRsp rats].

Concentration-dependent positive chronotropic response to phenylephrine (Phe) mediated by alpha 1-adrenoceptor in isolated normotensive and SHRsp rat right atria was determined under normal or depressed beat rate by stimulation of cholinergic M-receptor. The spontaneous beat rate was increased from 223 +/- 18 to 271 +/- 16 bpm by Phe 100 mumol.L-1 in the presence of propranolol 1 mumol.L-1. When the basal rate was lowered by stimulation of cholinergic M-receptor with carbachol, PE-induced increment of beat rate was enhanced to 101 +/- 23 bpm, accompanied by an increase of the force of contraction from 45 +/- 14% to 125 +/- 56% (vs control response). However, beta-adrenoceptor mediated positive chronotropic effect was attenuated in the presence of carbachol, and no positive inotropic effect was detected. PE-induced increase in beat rate in SHRsp (31 +/- 9 bpm) was lower than that in WKY (41 +/- 10 bpm). After pretreatment with carbachol, Phe caused increments in beat rate in SHRsp and WKY were 70 +/- 18 bpm and 114 +/- 17 bpm, respectively. It is suggested that in SHRsp, the function of cardiac alpha 1-adrenoceptor is lower than that in WKY.

Animals↗

PubMed1992

TGF beta signals through a heteromeric protein kinase receptor complex.

Transforming growth factor beta (TGF beta) binds with high affinity to the type II receptor, a transmembrane protein with a cytoplasmic serine/threonine kinase domain. We show that the type II receptor requires both its kinase activity and association with another TGF beta-binding protein, the type I receptor, to signal growth inhibition and early gene responses. Receptors I and II associate as interdependent components of a heteromeric complex: receptor I requires receptor II to bind TGF beta, and receptor II requires receptor I to signal. This mode of operation points to fundamental differences between this receptor and the protein-tyrosine kinase cytokine receptors.

Amino Acid Sequence↗

PubMed1992

Expression cloning of the TGF-beta type II receptor, a functional transmembrane serine/threonine kinase.

A cDNA encoding the TGF-beta type II receptor protein has been isolated by an expression cloning strategy. The cloned cDNA, when transfected into COS cells, leads to overexpression of an approximately 80 kd protein that specifically binds radioiodinated TGF-beta 1. Excess TGF-beta 1 competes for binding of radioiodinated TGF-beta 1 in a dose-dependent manner and is more effective than TGF-beta 2. The predicted receptor structure includes a cysteine-rich extracellular domain, a single hydrophobic transmembrane domain, and a predicted cytoplasmic serine/threonine kinase domain. A chimeric protein containing the intracellular domain of the type II receptor and expressed in E. coli can phosphorylate itself on serine and threonine residues in vitro, indicating that the cytoplasmic domain of the type II receptor is a functional kinase. This result implicates serine/threonine phosphorylation as an important mechanism of TGF-beta receptor-mediated signaling.

Amino Acid Sequence↗

PubMed1992

Expression cloning of TGF-beta receptors.

Using a powerful expression cloning method in COS cells, we have cloned the TGF-beta types II and III receptors. The type III TGF-beta receptor is a membrane-bound proteoglycan with a core protein of about 110 kDa. Stable expression of the type III receptor in L6 myoblasts leads to an apparent increase in the ability of the type II receptor to bind iodinated TGF-beta 1. The cloned type II receptor has a predicted protein core of about 60 kDa with a cysteine-rich extracellular domain, a single transmembrane domain, and a functional serine/threonine kinase domain that is homologous to the activin receptor and to the C. elegans protein daf-1. These results implicate serine/threonine phosphorylation as an important mechanism of TGF-beta action.

Animals↗

PubMed1992

Biplane transesophageal echocardiography: an anatomic-ultrasonic-clinical correlative study.

In 427 subjects TEE was performed with either a uniplane or biplane transducer; in seven cadavers the cardiac anatomic segments were observed in several levels and directions. Nine transverse and six longitudinal views were compared with the corresponding cardiac anatomic segments. Based on this correlative study, the levels of segments, insertion depth, anatomic structure identification, image characteristics, clinical applications, and the advantages as well as the limitations of biplane TEE are discussed.

Adolescent↗

PubMed1992

The relationship between intracardiovascular smoke-like echo and erythrocyte rouleaux formation.

Intravascular smoke-like echo always appears in regions of stasis, but the exact mechanism of its production is unclear. We investigated its appearance in relation to erythrocyte rouleaux formation. To study this relationship we performed a series of in vitro and animal experiments. In the in vitro study, we observed an erythrocyte suspension by ultrasonography and found it to be echo-free. Under the microscope, red blood cells were observed in a dispersed state. If an equal amount of lymphocyte separation solution was added to the suspension, smoke-like echo appeared, and red blood cells were seen in a rouleaux pattern. In animal (mongrel dogs) experiments, under physiologic conditions with normal blood flow velocity, all cardiac cavities and the inferior vena cava were echo-free. When stasis was induced experimentally in the inferior vena cava, red blood cells aggregated to form rouleaux and smoke-like echo appeared. On resumption of normal blood flow, the rouleaux dispersed to form erythrocytes again. The mechanism of production of intracardiovascular smoke-like echo is closely related to the formation of erythrocyte rouleaux. When rouleaux are formed, they become larger and appear nearer or larger than the ultrasonic wavelength. Thus reflections are produced and smoke-like echo appears.

Animals↗

PubMed1992

Unit activity to click CS changes in dorsal cochlear nucleus after conditioning.

Recordings were made of single unit activity (n = 360 units) from the dorsal cochlear nucleus of cats. Different patterns of activity were elicited by acoustic stimuli before and after Pavlovian conditioning. The peak response to a forward paired click conditioned stimulus (CS) increased whereas that to a backward paired hiss discriminative stimulus (DS) did not. The percentage of units responding to the CS increased from 34% to 46% after conditioning. The findings do not support the widely accepted hypothesis that learning has no effect on transmission through the first brain stem relay of the auditory system and indicate, instead, that the cochlear nucleus can participate in complex adaptive acoustic signal processing.

Acoustic Stimulation↗

PubMed1992

[Studies on transdermal delivery system of isosorbide dinitrate].

A transdermal delivery system of isosorbide dinitrate (ISDN-TDS) and an HPLC method for the measurement of ISDN were developed. The system is composed of backing, drug reservoir, control membrane, contact adhesive and protective layer. The influences of drug reservoir, solvent, control membrane, viscosity and penetration enhancer azone on the release of ISDN were investigated. The cumulative released amount of ISDN/time profile indicated that ISDN was permeated through excised skin in a zero-order kinetic in 48 h. The release of ISDN from ISDN-TDS can last 72 h at least. The mean permeation rate is 13.76 micrograms.h-1/cm2. Releasing ISDN from ISDN-TDS was more stable than that from Frandol tape-s whose release profile was found to follow a linear Q vs t1/2 relationship with a release flux of 114.39 micrograms.h-1/cm2.

Administration, Cutaneous↗

PubMed1992

[Anti-lipid peroxidation and protective effects of phenytoin sodium on ischemic myocardium of mice].

Isoproterenol (Iso, 20 mg.kg-1 x d-1 x 2 d) induced widespread and severe myocardial damages at ultrastructural level, decreased the myocardial Se-glutathione peroxidase (Se-GSH-Px) and superoxide dismutase (SOD) activities, increased the serum creatine phosphokinase (CPK) concentration and myocardial malondialdehyde (MDA) content. Phenytoin sodium (Phe) 15 or 30 mg.kg-1 ip pretreatment diminished the CPK release and MDA production, protected the Se-GSH-Px activity in the Iso-induced damage of mouse heart. The pretreatment with 30 mg.kg-1 abated the reduction of SOD activity. However, Phe 15 mg.kg-1 did not show such an effect. Phe (15 or 30 mg.kg-1) reduced the ultrastructural cardiotoxicity of Iso, and the membrane structure of ischemic myocardium was protected. The protective effects of verapamil pretreatment 3 mg.kg-1 ip were weaker than those of Phe on ultrastructural changes, but biochemical changes were similar to those of Phe. The results suggested that Phe possessed anti-lipid peroxidation and protective effects on ischemic myocardium.

Animals↗