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Biomedical subjects

X S Yang

Publications and source records attributed to X S Yang.

At least 19 recordsLinked to original sources
PubMed2006

No association of C-1019G promoter polymorphism of 5-HT1A receptor gene with migraine.

It is well known that migraine has a strong genetic component, although the type and number of genes involved remains unclear. There is evidence to suggest that serotonin-related genes may be involved in the pathogenesis of migraine. To investigate whether the 5-HT1A receptor gene contributes to the risk of migraine we performed an association study of C-1019G promoter polymorphism of the gene in 102 migraineurs and 93 controls. Subjects were of Han Chinese origin. No significant differences in allele (P=0.82) or genotype frequencies (P=0.71) were seen in migraineurs compared with the controls. When migraine with aura, without aura, with family history, without family history were analyzed separately, the frequencies did not vary significantly. Our results suggest that C-1019G in 5-HT1A is not a major genetic risk factor for migraine.

Adult↗
PubMed2001

Bicarbonate and fluid secretion evoked by cholecystokinin, bombesin and acetylcholine in isolated guinea-pig pancreatic ducts.

1. HCO3- secretion was investigated in interlobular duct segments isolated from guinea-pig pancreas using a semi-quantitative fluorometric method. Secretagogue-induced decreases in intracellular pH, following blockade of basolateral HCO3- uptake with a combination of amiloride and DIDS, were measured using the pH-sensitive fluoroprobe BCECF. Apparent secretory HCO3- fluxes were calculated from the initial rate of intracellular acidification. 2. In the presence of HCO3-, stimulation with secretin (10 nM) or forskolin (5 microM) more than doubled the rate of intracellular acidification. This effect was abolished in the absence of HCO3-. It was also abolished in the presence of HCO3- when DIDS and NPPB were applied to the luminal membrane by microperfusion. We therefore conclude that the increase in acidification rate is a useful index of secretagogue-induced HCO3- secretion across the luminal membrane. 3. Secretin, cholecystokinin (CCK) and bombesin each stimulated HCO3- secretion in a dose-dependent fashion. They evoked comparable maximal responses at about 10 nM and the EC50 values were 0.5 nM for secretin, 0.2 nM for CCK and 30 pM for bombesin. Acetylcholine (ACh) was also effective, with a maximum effect at 10 microM. 4. The stimulatory effect of CCK was blocked completely by the CCK1 receptor antagonist devazepide but not by the CCK2 receptor antagonist L365,260. The CCK analogue JMV-180 (Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-phenylethyl ester), which is an agonist of the high-affinity CCK1 receptor but an antagonist of the low-affinity receptor, also stimulated HCO3- secretion but with a smaller maximal effect than CCK. JMV-180 partially inhibited the response to a high concentration of CCK but not to a lower concentration, suggesting that both high- and low-affinity states of the CCK1 receptor evoke HCO3- secretion. 5. The stimulatory effect of bombesin was blocked completely by the gastrin-releasing peptide (GRP) receptor antagonist D-Phe6-bombesin(6-13)-methyl ester (BME) but not by the neuromedin B (NMB) receptor antagonist D-Nal-cyclo[Cys-Tyr-D-Trp-Orn-Val-Cys]-Nal-NH2 (BIM-23127). 6. Secretagogue-evoked fluid secretion was also examined using video microscopy to measure the rate of swelling of ducts whose ends had sealed during overnight culture. Secretin, CCK, bombesin and ACh all evoked fluid secretion with maximal rates of approximately 0.6 nl x min(-1) x mm(-2), and with concentration dependences similar to those obtained for HCO3- secretion. 7. We conclude that CCK, bombesin and ACh stimulate the secretion of a HCO3--rich fluid by direct actions on the interlobular ducts of the guinea-pig pancreas and that these responses are mediated by CCK1 receptors, GRP receptors and muscarinic cholinoceptors, respectively.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2001

Clinical and echocardiographic characteristics of papillary fibroelastomas: a retrospective and prospective study in 162 patients.

BACKGROUND: Cardiac papillary fibroelastoma (CPF) is a primary cardiac neoplasm that is increasingly detected by echocardiography. The clinical manifestations of this entity are not well described. METHODS AND RESULTS: In a 16-year period, we identified patients with CPF from our pathology and echocardiography databases. A total of 162 patients had pathologically confirmed CPF. Echocardiography was performed in 141 patients with 158 CPFs, and 48 patients had CPFs that were not visible by echocardiography (<0.2 cm), leaving an echocardiographic subgroup of 93 patients with 110 CPFs. An additional 45 patients with a presumed diagnosis of CPF were identified. The mean age of the patients was 60+/-16 years of age, and 46.1% were male. Echocardiographically, the mean size of the CPFs was 9+/-4.6 mm; 82.7% occurred on valves (aortic more than mitral), 43.6% were mobile, and 91.4% were single. During a follow-up period of 11+/-22 months, 23 of 26 patients with a prospective diagnosis of CPF that was confirmed by pathological examination had symptoms that could be attributable to embolization. In the group of 45 patients with a presumed diagnosis of CPF, 3 patients had symptoms that were likely due to embolization (incidence, 6.6%) during a follow-up period of 552+/-706 days. CONCLUSIONS: CPFs are generally small and single, occur most often on valvular surfaces, and may be mobile, resulting in embolization. Because of the potential for embolic events, symptomatic patients, patients undergoing cardiac surgery for other lesions, and those with highly mobile and large CPFs should be considered for surgical excision.

Adolescent↗
PubMed2001

Chaos in small-world networks.

A nonlinear small-world network model has been presented to investigate the effect of nonlinear interaction and time delay on the dynamic properties of small-world networks. Both numerical simulations and analytical analysis for networks with time delay and nonlinear interaction show chaotic features in the system response when nonlinear interaction is strong enough or the length scale is large enough. In addition, the small-world system may behave very differently on different scales. Time-delay parameter also has a very strong effect on properties such as the critical length and response time of small-world networks.

Journal Article↗
PubMed2001

Respiratory variation of mitral and pulmonary venous Doppler flow velocities in constrictive pericarditis before and after pericardiectomy.

The objective of this study was to determine whether Doppler echocardiography is useful in assessing the effects of pericardiectomy in patients with constrictive pericarditis by studying the postoperative change in the respiratory variation of mitral inflow and pulmonary venous Doppler flows. The study population consisted of 35 cases with surgically proven constrictive pericarditis. Thirty-five patients had preoperative Doppler echocardiography, whereas 4 patients died of non-cardiac causes and 1 patient had a heart transplant before follow-up. Postoperative studies were performed at a mean of 1081 +/- 84 days (range 120-2700 days) after pericardiectomy. The mean (+/- SD) respiratory variation changed after surgery from a baseline value of 17% +/- 14% to 8% +/- 8% for peak mitral E velocity (P <.01); from 25% +/- 18% to 7% +/- 13% (P <.001) for pulmonary venous (PV) peak diastolic flow velocity, and from 21% +/- 13% to 11% +/- 13% (P =.009) for PV peak systolic flow velocity. The 23 patients who became asymptomatic after surgery had a significantly lower mean mitral and PV respiratory variation than the 7 patients who were NYHA class II (4% +/- 4% and 6% +/- 4% vs 21% +/- 6% and 19% +/- 10%, respectively, P <.0001 for both). Pulsed Doppler echocardiographic assessment of respiratory variation is useful for evaluating the outcome of pericardiectomy.

Aged↗
PubMed1998

Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation.

OBJECTIVES: To develop and validate an automated noninvasive method to quantify mitral regurgitation. BACKGROUND: Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR). METHODS: First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied. RESULTS: In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml). CONCLUSIONS: We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.

Adult↗
PubMed1997

Comparison of mortality rates and progression of left ventricular dysfunction in patients with idiopathic dilated cardiomyopathy and dilated versus nondilated right ventricular cavities.

This study assesses the influence of right ventricular (RV) dilation on the progression of left ventricular (LV) dysfunction and survival in patients with idiopathic dilated cardiomyopathy (IDC). Using transthoracic echocardiography, we studied 100 patients with IDC aged 20 to 80 years (mean 55 +/- 14); 67% were men. In the apical 4-chamber view, diastolic LV and RV chamber area measurements classified patients into 2 groups: group RV enlargement+ (RV area/LV area > 0.5) included 54 patients; group RV enlargement- (no RV enlargement) had RV area/LV area < or = 0.5. Echocardiographic studies were repeated in all patients after a mean of 33 +/- 16 months. At the time of the initial study, the 2 groups did not differ in age, gender, incidence of atrial fibrillation and diabetes, left ventricular mass, and LV ejection fraction, but the RV enlargement+ group had more severe tricuspid regurgitation and less LV enlargement. After 47 +/- 22 months (range 12 to 96), patients in group RV enlargement+ had lower LV ejection fraction (29% vs 34%, p = 0.006) than patients with initial RV enlargement-. At clinical follow-up, mortality was higher (43%) in patients with initial RV enlargement+ than the RV enlargement- patients (15%), p = 0.002. For survivors, the mitral deceleration time averaged 157 +/- 36 ms; for nonsurvivors or patients who required transplant, the mitral deceleration time averaged 97 +/- 12 ms (p < 0.0001). With use of a multivariate Cox model adjusting for LV ejection fraction, LV size, and age, the relative risk ratio of mortality from initial RV enlargement+ was 4.4 (95% confidence limits 1.7 to 11.1) (p = 0.002). Thus, patients with significant RV dilation had nearly triple the mortality over 4 years and more rapidly deteriorating LV function than patients with less initial RV dilation. In IDC, RV enlargement is a strong marker for adverse prognosis that may represent a different morphologic subset.

Adult↗
PubMed1997

Optical characterization of a novel GABA response in early embryonic chick brainstem.

To examine the functional expression of embryonic GABA receptors, the inhibitory effects were studied of GABA (GABA responses) on the excitatory postsynaptic potentials evoked by vagal stimulus in seven- to 10-day-old embryonic chick brainstem slice preparations. A multiple-site optical recording technique was used, with a multiple element photodiode array system and a fast voltage-sensitive merocyanine-rhodanine dye (NK2761). First, in the GABA response, three components were pharmacologically identified: component 1, related to GABA(A) receptors; component 2, related to GABA(B) receptors; and component 3 which is insensitive to GABA(A) and GABA(B) antagonists, but is stimulated by both GABA(A) and GABA(B) agonists. Subsequently. the embryogenesis and early development of the three components were investigated, and early developmental maps of regional distribution patterns of the three components were constructed. Components 1 and 3 have already emerged in the seven-day-old embryonic brainstem preparation; component 2 appeared in the eight-day-old preparations. No component related to GABA(C) receptors was observed in the seven- to 10-day-old embryonic stages. From the pharmacological properties of component 3, we suggest that it is related to a new subtype, the GABA(D) receptor.

Animals↗
PubMed1997

Photometric assessment of volume changes coupled with membrane potential in valinomycin-incorporated red blood cells.

Employing photometric methods, we have attempted to derive a possible quantitative relationship between volume change and membrane potential for valinomycin-incorporated red blood cells. The cells, collected from a human, rats or bullfrogs, were suspended in test solutions composed of a mixture of NaCl and KCl in varying proportions. The osmolality of the suspending medium was appropriately fixed at different values. After the addition of valinomycin to the suspension, changes in optical density (turbidity) at 620 nm and in fluorescence from a voltage-sensitive permeant dye (diS-C3-[5]) were measured in different concentrations of external potassium ions. The changes in optical density and fluorescence intensity were converted into relative cell volume and membrane potential changes in the test cells, respectively. Cell volume increased with depolarization of the membrane. We derived an empirical equation for the volume change versus membrane potential relation curves obtained experimentally, and have also shown that the observed volume change may be plausibly represented by a hyperbolic function of transmembrane potential involving the medium osmolality as an important parameter.

Animals↗
PubMed1995

Photometric determination of phenomenological correlation between osmotic behavior and hemolysis of red blood cells.

The osmotic behavior of red blood cells from a human and from several other mammalian species was studied by photometric measurements. When red blood cells were suspended in sodium chloride solutions with various osmotic concentrations, the optical density at 620 nm was reciprocally related to the relative volume of the red cells. Thus, we evaluated the osmotic volume changes in the red cells from optical density measurements. The Boyle-van't Hoff relation was applicable to the osmotic behavior of red cells which responded as a complete osmometer in hypertonic and slightly hypotonic (lower than about 240 mOsm) solutions. Also, we examined the rheological correlation between osmotic volume changes and hemolysis. Osmotic hemolysis occurred corresponding to breakdown of the Boyle-van't Hoff relation in hypotonic solutions. The critical osmotic concentration for the breakdown of the Boyle-van't Hoff relation was that for osmotic hemolysis. In Na2SO4 solutions, although the critical osmotic concentration shifted towards a smaller value, the critical volume for the breakdown of the Boyle-van't Hoff relation and for osmotic hemolysis was maintained at a constant value, indicating that the onset of osmotic hemolysis depends exclusively upon the critical volume. In the samples from a human, the critical volume for the onset of hemolysis was estimated to be 1.25 +/- 0.05 in the ratio to the normal volume in iso-osmotic solution. From these obtained results, it is suggested that the red cell behaves in hypotonic solutions as a viscoelastic body of the type represented by the Voigt model, and the viscoelastic breakdown of the membrane results in osmotic hemolysis in hypotonic solution.

Animals↗
PubMed1993

Serum isoforms of creatine kinase MM isoenzyme in acute myocardial infarction.

Using the electrophoretic method, the changes in the catalytic activities of three CK-MM isoforms in multiple sequential serum samples of 12 patients with acute myocardial infarction (AMI) were monitored for 3 days after the onset of chest pain. In post-AMI period, MM3 reached a peak (518.6 U/L) first, on the average 14.0 hours after AMI, followed by MM2 (19.8 h, 640.5 U/L) and MM1 (28.7 h, 641.3 U/L). According to their faster decay from circulation, MM3 had higher fractional disappearance and appearance rates, followed by MM2 and MM1. The MM3/MM1 activity ratio rose beyond the upper limit, found in health subjects, about 3.5 hours after onset of symptom and peaked on an average 10.6 hours after AMI, even earlier than the peaks of all isoforms, CK and CK-MB. On the other hand, our findings indicated these changes in isoform composition can be of value in estimating the time elapsed since the onset of tissue damage; MM3 is the predominant isoform when the tissue necrosis is of relatively recent origin (5-15 h); MM2 is the dominant subband between 15 and 24 hours after AMI, whereas a predominant MM1 band would indicate a significantly longer time period since the injury occurred (24 hours or more). Thus, these characteristics make CK-MM isoforms an earlier and more sensitive indicator of acute release from necrotic myocardium and an effective mean of predicting the time of the onset of AMI.

Adult↗
PubMed1993

[A comparison between diltiazem SR and diltiazem HCL in the treatment of angina pectoris].

This study included 168 patients with angina pectoris, who were divided into two groups, the diltiazem SR (No. 88) group and diltiazem HCL (No. 80) group. The two groups were comparable in age and duration of coronary heart disease. The results were as follows: (1) The total clinical effect of diltiazem SR (94.3%) was slightly greater than that of diltiazem HCL (82.5%), the effect in ECG improvement was 53.3% and 53.4% respectively. (2) The rate of adverse effect was 12.5% in diltiazem SR group and 14.4% in diltiazem HCL group. It is concluded that the two different types of diltiazem have similar effect in the treatment of angina pectoris. However, it is more convenient to take diltiazem SR than diltiazem HCL as the former needs only twice a day.

Adult↗
PubMed1991

Ketanserin in the treatment of hypertension: a multicentre dose-finding study in China.

The effect of ketanserin at 5 mg, 10 mg and 20 mg twice daily for 3 months was studied in Chinese patients with hypertension. Both 10 mg and 20 mg doses twice daily effectively reduced systolic and diastolic pressures, while 5 mg twice daily was not effective. The 20 mg regimen was more effective than 10 mg in reducing diastolic, but not systolic pressures. Blood pressure reduction was progressive up to 1 month of treatment but not thereafter. Neither first-dose hypotension nor postural hypotension were seen. There were no effects on body weight or heart rate. A nominally significant 6 msec increase in QTc was seen with 10 mg, but not with 5 or 20 mg twice daily; this could be a chance finding. The side-effect burden was light, and decreased with time.

Blood Pressure↗
PubMed1990

[Diagnostic changes in serum creatine kinase MM isoenzyme sub-bands after the onset of acute myocardial infarction].

The authors quantified the change of CK-MM isoforms in the first available serum sample from 16 patients each with acute myocardial infarction (AMI) and angina pectoris and 16 normal individuals as well. The average MM3/MM1 ratio in the normal group was 0.24 +/- 0.12, in angina group 0.21 +/- 0.13, and in AMI group 0.52 +/- 0.30 (P less than 0.001, as compare with the first two groups). The first blood sample of AMI was obtained in 3.0 +/- 1.9 hours after the onset of chest pain. Half of them (8/16) had a ratio of MM3/MM1 greater than 0.50 and the change occurred as early as 30 min after the attack. In contrast, the total CK and CK-MB in the three groups were within normal limits at the same time, they were 85.8 +/- 24.4 U/L for CK and 3.2 +/- 1.1% for CK-MB in patients with AMI, 66.7 +/- 18.0 U/L, 2.7 +/- 1.6% in angina pectoris and 71.4 +/- 24.5 U/L, 3.0 +/- 1.1% in normal subjects respectively. Accordingly, diagnostic change of CK-MM isoforms was the earliest among the enzymes after the onset of AMI.

Aged↗
PubMed1989

[Hemodynamic study of a single oral dose of enalapril in patients with heart failure].

Clinical and hemodynamic studies were carried out for the purpose of evaluating the effects of enalapril in the treatment of chronic heart failure. Enalapril 10-20 mg was given once to 10 patients with moderate to severe congestive heart failure (coronary 6, hypertensive heart disease 2 and idiopathic congestive cardiomyopathy). Hemodynamic studies were done on the first day after drug administration and the same dose was maintained for 2 weeks. The results showed a decrease of mean BP of 18.29% (P less than 0.01), CVP 40.4% mPAP 23.9%, PCWP 41.2%, SVR 39.9% and PVR 41.3% respectively (P less than 0.001). Cardiac index increased 44.16% (P less than 0.001). The therapeutic action lasted more than 24 hours after a single dose. No further drop of BP was found weeks later, 6 patients in NYHA class III and 2 in class IV improved to class II. No severe side effects were found. The results showed that enalapril is well tolerated after a single dose and its therapeutic action lasts 2 weeks with improvement both in hemodynamics and subjective symptoms.

Administration, Oral↗
PubMed1989

[Effect of tyrosine on progesterone and hCG production by human trophoblast cells in vitro].

The purpose of the present study was to investigate the effect of tyrosine on progesterone and hCG production by human placental cells in vitro. The results showed that the three concentrations (0.02 mmol/L, 0.2 mmol/L and 2mmol/L) of tyrosine inhibited progesterone secretion by trophoblast cells in vitro. While progesterone secretion was suppressed by tyrosine, hCG secretion was unchanged. Thus, it seems unlikely that the suppression of progesterone production by tyrosine was due to a decrease in hCG production. It was further demonstrated that tyrosine inhibited 3 beta-HSD activity of trophoblast cells, indicating that the progesterone production inhibition by them might be due to the decreased 3 beta-HSD activity of trophoblast cells.

3-Hydroxysteroid Dehydrogenases↗