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Biomedical subjects

H B Xiao

Publications and source records attributed to H B Xiao.

At least 19 recordsLinked to original sources
PubMed2005

Capillary liquid chromatography-microcoil 1H nuclear magnetic resonance spectroscopy and liquid chromatography-ion trap mass spectrometry for on-line structure elucidation of isoflavones in Radix astragali.

Miniaturization and hyphenation of chromatographic separation techniques to nuclear magnetic resonance spectroscopy is being increasingly demanded in the field of biomedical, drug metabolite and natural product analysis. Herein, capillary liquid chromatography was coupled on-line to microcoil 1H nuclear magnetic resonance spectroscopy (capLC-NMR) equipped with a 1.5 microL solenoidal probe for structure elucidation of isoflavones in Radix astragali. The extract was screened by HPLC-UV-MS as the preliminary step and four major peaks were identified tentatively by ion trap mass spectrometry molecular weights and characteristic fragments. Then, stopped-flow capLC-UV-NMR was performed using 33 microg extract injected on-column. The four peaks were parked manually in the micro probe one by one and corresponding 1H NMR spectra were recorded with good resolutions under the applied capLC-NMR conditions (120 and 220 ng injected on-column for peaks 2 and 4, respectively). All aromatic regions of 1H NMR spectra correlated well to the characteristic signals of isoflavone aglycone protons. And the signal corresponding to the anomeric proton of the glucopyranoside of isoflavone glycoside was also obtained for peak 1. Therefore, these four peaks are determined as calycosin-7-O-beta-D-glucopyranoside (1), ononin (2), calycosin (3) and formononetin (4) unambiguously. The capLC-NMR results indicate that this hyphenated technique could be used for the determination of a great variety of natural products from small sample amounts, e.g., only 5 g R. astragali in this study.

Aconitum↗
PubMed2004

Determination and identification of isoflavonoids in Radix astragali by matrix solid-phase dispersion extraction and high-performance liquid chromatography with photodiode array and mass spectrometric detection.

The isoflavonoids in Radix astragali were determined and identified by HPLC-photodiode array detection-MS after extraction employing matrix solid-phase dispersion (MSPD). As a new sample preparation method for R. astragali, the MSPD procedure was optimized, validated and compared with conventional methods including ultrasonic and Soxhlet extraction. The amounts of two major components in this herb, formononetin (6) and ononin (2), were determined based on their authentic standards. Four major isoflavonoids, formononetin (6), ononin (2), calycosin (5) and its glycoside (1), and three minor isoflavonoids, (6aR,11aR)-3-hydroxy-9, 10-dimethoxypterocarpan (7), its glycoside (3), and (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavone-7-O-beta-D-glycoside (4), were identified based on their characteristic two-band UV spectra and [M + H], [aglycone + H]+ and [A1 + H]+ ions, etc. The combined MSPD and HPLC-DAD-MS method was suitable for quantitative and qualitative determination of the isoflavonoids in R. astragali.

Astragalus Plant↗
PubMed2001

Influence of L-methionine-deprived total parenteral nutrition with 5-fluorouracil on gastric cancer and host metabolism.

AIM: To investigate the influence of L-methionine-deprived total parenteral nutrition with 5-FU on gastric cancer and host metabolism. METHODS: N-methyl-N'-nitro-nitrosoguanidine (MNNG) induced gastric cancer rats were randomly divided into four groups: Met-containing TPN group (n=11), Met-deprived TPN group (n =12), Met-containing TPN+5-FU group (n=11) and Met-deprived TPN+5-FU group (n=12). Five rats in each group were sacrificed after 7 days of treatment and the samples were taken for examination. The remaining rats in each group were then fed separately with normal diet after the treatment until death, the life span was noted. RESULTS: The tumors were enlarged in Met-containing group and shrank in Met-deprived group markedly after the treatment. The DNA index (DI) of tumor cells and the body weight (BW) of rats had no significant change in the two groups, however, the ratio of tumor cells'S phase was increased. The ratio of G2M phase went up in Met-containing group, but down in Met-deprived group. In the other two groups that 5-FU was added, the BW of rats, and the diameter of tumors, the DI of tumor cells, the S and G2M phase ratio of tumor cells were all decreased, particularly in Met-deprived plus 5-FU group. Pathological examination revealed that the necrotic foci of the tumor tissue increased after Met-deprived TPN treatment, and the nucleoli of tumor cells enlarged. In MetTPN+5-FU group, severe nuclear damage was also found by karyopyknosis and karyorrhexis, meanwhile there was slight degeneration in some liver and kidney cells. The serum free Met and Cysteine decreased markedly (P<0.001), while other amino acids, such as serum free serine and glutamine increased significantly (P<0.005). All the rats died of multiple organ failure caused by cancer metastasis. The average survival time was 18.6 days in Met-containing TPN group, 31 days in Met-deprived TPN group, 27.5 days in Met-containing TPN+5-FU group, and 43 days in Met-deprived TPN+5-FU group (P<0.05). CONCLUSION: Met-deprived TPN causes methionine starvation of tumor cells, and can enhance the anti-tumor effect of 5-FU and prolong the life span of gastric cancer bearing rats.

Animals↗
PubMed2000

[Application of the quantitation with curve-fitting method on chiral separation by high performance liquid chromatography].

We propose for the first time that curve-fitting method should be applied to the quantitation of overlapping peaks in chiral separation by high performance liquid chromatography (HPLC). We have examined the separation of eight isomers of cyfluthrin on a chiral stationary phase (CSP), and found that in comparing with the perpendicular-drop method, the accuracy of quantitation of overlapping peaks with curve-fitting was much higher. Generally, errors in peak area measurement using the perpendicular-drop method become larger as the degree of peak overlap increases. Meanwhile, by using curve-fitting method errors have no apparent difference for different degrees of peak overlap. Generally, for the same chiral compounds, although the resolutions are different with different mobile phase strength, the results of peak areas are the same by using curve-fitting method.

Chromatography, High Pressure Liquid↗
PubMed2000

[Analysis of ginsenosides by high performance liquid chromatography/mass spectrometry/mass spectrometry(LC/MS/MS)].

Ginseng, one of the most popular medicinal herbs used in traditional Chinese medicines, has been studied to have biological effects attributing to its main constituents such as ginsenosides. There are more than 30 kinds of ginsenosides and some of them have similar polarity and structure. Thus, it is difficult to separate those ginsenosides with isocratic mobile phase owing to their similar polarity. A reversed-phase high performance liquid chromatographic method with gradient elution has been developed in this work. Nine ginsenosides can be separated by this method. Among them, five ginsenosides with different molecular weights can be determined by means of their molecular weight gained through LC/MS with an ESI interface. Re and Rd have the same Mw but belonging to two different kinds of ginsenosides. They can be differentiated from each other through their MS/MS gained by CID(collision induced decomposition) at the second stage quadrapole. Rc and Rb3 having the same molecular weight and belonging to the same kind of ginsenoside can be distinguished through their negative ion spectra gotten from LC/MS. So 9 ginsenosides can be determined by LC/MS/MS. This method can also be used to determine the ginsenosides contained in commercially available samples.

Chromatography, High Pressure Liquid↗
PubMed2000

[Simultaneous determination of sulbactam sodium and cefoperazone sodium in sulperazon by high performance liquid chromatography].

A reversed-phase, isocratic high performance liquid chromatographic method with acid mobile phase can separate sulbactam and cafoperazone within 12 minutes. Column packed with Hypersil ODS2(250 mm x 4.6 mm i.d., 5 microns) was manufactured by Dalian Elite Company. Mobile phase is composed of water (adjusted to pH 4.0 with 1% phosphoric acid) and acetonitrile (80:20, V/V). The detection was performed at 210 nm and the injection volume was 2 microL. Cefoperazone and sulbactam have good linearity in the ranges of 100 mg/L to 800 mg/L and 100 mg/L to 1,000 mg/L with the correlation coefficients of 0.9991 and 0.9997 respectively. This method is easily to be operated and can be applied for manufacturing and medicinal study.

Anti-Infective Agents, Urinary↗
PubMed1996

Natural history of abnormal conduction and its relation to prognosis in patients with dilated cardiomyopathy.

To investigate the natural history of disturbances in ventricular activation, atrioventricular conduction, and ventricular cavity size, we retrospectively studied 58 patients from a total of 296 patients with dilated cardiomyopathy seen within 4 years. A total of 309 computerised electrocardiograms (ECGs) and 135 M-mode echocardiograms were analysed. In the majority of the patients, PR interval, QRS duration and QT interval prolonged progressively, though heart rate changed little. Their increase was much more striking in patients who died (n = 10) or had a pacemaker inserted (n = 9), compared to that in the clinically stable patients, though at entry all these values, as well as age and left ventricular cavity size, were similar. There were no significant differences between patients who died and those with a pacemaker inserted, except for QRS axis, which had shifted rightwards in 8 out of 10 who died, but only in 3 of 9 who subsequently had a pacemaker inserted and 14 of the 29 stable patients. A QRS duration over 160 ms was found in 8 out of the 10 patients who died, 6 of 9 who had a pacemaker and only in 5 out of the 39 stable patients (P < 0.001). The sum of PR interval and QRS duration over 375 ms was not found in any stable patient but was present in 6 of the 7 patients who were in sinus rhythm and died (P < 0.001). Left ventricular cavity size also increased with time, but did not correlate significantly with ECG progression, nor did it identify patients who subsequently died. Thus, a combination of increasing PR interval and QRS duration, particularly along with rightwards shift of QRS axis, appears to be a marker of high risk in patients with dilated cardiomyopathy.

Adult↗
PubMed1996

Absent septal q wave on electrocardiogram: a forgotten marker of myocardial disease.

Though absence of the septal q wave on a standard ECG was recognised by Willem Einthoven, this abnormality has received little attention. Nevertheless it is common in patients with coronary artery disease, and strongly associated with fibrosis of the septum with or without infarction. Furthermore, the associated disturbance of ventricular activation has clear mechanical consequences, impairing both systolic and diastolic left ventricular performance. Its structural, functional, and possible prognostic significance combined with ease of its detection all suggest that the cardiographic sign of absence of the septal q wave should be more widely recognised as a noninvasive marker of ventricular disease.

Biomarkers↗
PubMed1996

Reappraisal of Thomas Lewis's place in the history of electrocardiography.

Thomas Lewis is among the most significant figures in the history of electrocardiography. In the late 1920s, he abandoned electrocardiography for other areas that he considered to be clinical science, in spite of the fact that he had made great contributions to the then new technique and that interest in this technique was increasing worldwide. The reasons why Lewis left electrocardiography are discussed further here. Lewis's leaving of electrocardiography had as much influence on the history of electrocardiography as did his practice of it.

Electrocardiography↗
PubMed1995

Association of reduced PR-AC interval with ventricular early potentials in dilated cardiomyopathy.

We studied 31 patients with dilated cardiomyopathy, correlating mitral valve cusp motion with the continuous wave Doppler signal of mitral regurgitation and the signal averaged electrocardiogram (ECG). Sixteen patients had a B point (early partial closure) on the mitral echogram and 15 did not. Fifteen normal cases were used as controls. The duration of ventricular early potentials (< 40 microV) was measured on the signal averaged ECG of the QRS complex. The PR interval was increased in patients with a B point (190 (33) ms vs. 145 (16) ms in normal, P < 0.01) and PR-AC interval was reduced (25 (71) ms vs. 65 (11) ms in normal, P < 0.05). The B point itself was effectively synchronous with the onset of low velocity early systolic mitral regurgitation, and followed the Q wave of the succeeding beat by 20 ms or less. Early low velocity on mitral regurgitation was not present in patients without a B point. The duration of early potentials was greatly increased in patients with a B point (43 (26) ms) compared both to those without (17 (20) ms, P < 0.01) and to normals (12 (7) ms, P < 0.01) and their duration correlated with B-C interval (r = 0.6, P < 0.02). We conclude that a B point on the mitral echogram in patients with left ventricular disease is due to early systolic low velocity mitral regurgitation which itself results from an abnormal pattern of left ventricular activation, probably bilateral bundle branch block. Once established, this low velocity jet delays complete mitral valve closure.

Adult↗
PubMed1995

Detection and localization of early diastolic forces within the left ventricle from inflow jet dynamics. A comparison between normal subjects and patients with dilated cardiomyopathy.

We studied the properties of the jet of blood entering the left ventricle from the left atrium during early diastole in 32 patients with dilated cardiomyopathy, and 24 normal subjects of similar age. The diameter of the jet was measured from the cross-sectional color Doppler image and its cross-sectional area (JA) was derived. Pulsed Doppler records of flow velocity were made at 1-cm intervals into the ventricle from the mitral ring. Peak (Vp) and mean (Vm) E wave velocity and time velocity integral (TVI) were determined. At any level in the ventricle, therefore, the early diastolic volume of blood remaining in the jet, i.e., the flow time integral, is given by JA.TVI; the local flow rate, Q, by JA.Vm; and jet momentum along the long axis of the ventricle by Q.Vp. In normals, the jet cross-sectional area fell from 5.9 (1.3) cm2 at the mitral ring to 4.9 (0.7) cm2 at 4 cm (P < 0.05), but the flow time integral fell proportionately more, from 46.0 (15.2) ml at the ring level to 15.9 (3.4) ml at 4 cm (P < 0.01). Axial momentum flux was 44 (13) x 10(2) cm4s-2 at the ring level, falling to 28 (10) x 10(2) cm4s-2 at 4 cm (P < 0.01). In dilated cardiomyopathy, the jet cross-sectional area was much smaller than normal, 1.9 (0.8) cm2 at the ring level, and it remained effectively constant, being 2.0 (0.9) cm2 at 6 cm (P < 0.01 vs normals).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Doppler reconstruction of left ventricular pressure from functional mitral regurgitation: potential importance of varying orifice geometry.

OBJECTIVE: To assess the left ventricular pressure pulse, in particular its time course, reconstructed from the continuous wave Doppler signal of functional mitral regurgitation using the simplified Bernoulli equation. DESIGN: Prospective study with simultaneously recorded high fidelity left ventricular pressure and continuous wave Doppler traces of functional mitral regurgitation, along with indirect left atrial pressure, electrocardiograms, and phonocardiograms. SETTING: Tertiary referral cardiac centre. PATIENTS: 9 patients (age 60 (17) years) were studied immediately before or 1-20 h after routine cardiac surgery. RESULTS: 104 cardiac cycles were analysed. There were no consistent differences between directly measured and reconstructed pressures in the time intervals from Q to + dP/dt (mean (SD) 125 (35) v 130 (35) ms and from Q to -dP/dt (389 (30) v 387 (28) ms or from Q to maximum pressure (267 (40) v 270 (40) ms, all P = NS). The time from Q to the onset of pressure rise (67 (30) v 64 (30) ms, P < 0.01) and the duration of total left ventricular systole (404 (50) v 408 (50) ms, P < 0.01) measured by the two methods were effectively identical, though the small difference was consistent enough to be statistically significant. The calculated peak pressure drop between the left ventricle and the left atrium (45-100 mm Hg) significantly underestimated left ventricular pressure (72-150 mm Hg; 70 (11) v 105 (15) mm Hg, P < 0.01) even if mean left atrial pressure (14 (4.0) mm Hg) was taken into account. Compared with those directly derived from left ventricular pressure, values of pressure measured at + dP/dt (26 (6.5) v 53 (10) mm Hg, P < 0.01) and -dP/dt (30 (8.0) v 60 (10) mm Hg, P < 0.01), and those of the rates of increase (675 (155) v 815 (155) mm Hg/s, P < 0.01) and fall (610 (145) v 845 (175) mm Hg, P < 0.01) were all significantly underestimated by Doppler. The underestimation in peak rates of pressure change could not entirely be explained by a scaling effect of absolute pressure. To investigate interrelations between the two methods throughout the cardiac cycle, reconstructed left ventricular pressure was plotted against the direct record. The plots confirmed that the reconstructed pressure was always less than directly measured pressure, the relative degree of underestimation falling as the pressure rose. This was not the effect of acceleration but probably reflects changing geometry of the regurgitant orifice. CONCLUSION: The continuous wave Doppler trace of functional mitral regurgitation is suitable for studying the timing of overall mechanical events and normalised rates of change of pressure in the left ventricle. Estimates of atrioventricular pressure drop by this method and particularly its absolute rates of change seem to be less reliable.

Adult↗
PubMed1995

Atrial electromechanical sequence in normal subjects and patients with DDD pacemakers.

OBJECTIVE: To assess the effect of right atrial appendage pacing on atrial electromechanical interrelations in patients with DDD pacemakers. DESIGN: Prospective study by M mode echocardiogram, Doppler echocardiogram, and apexcardiogram, along with electrocardiogram and phonocardiogram. SETTING: Tertiary cardiac referral centre. PATIENTS: 20 patients with DDD pacemakers and 20 age matched normal controls. RESULTS: Age, RR interval, atrial size, left ventricular size, and fractional shortening were similar in the two groups. Atrial electromechanical delay (the time from the onset of P wave or atrial pacing spike on ECG to the onset of atrial contraction on M mode echogram) was 68 (SD 7) ms at the lateral site of right atrium, 82 (9) ms at the central fibrous body, 93 (11) ms at the lateral site of left atrium in normals. In patients with DDD pacing, however, this delay increased to 85 (22) ms, 117 (23) ms, and 138 (25) ms respectively (all P < 0.01). Interatrial mechanical delay (the time from the onset of right atrial motion to the onset of the left) increased from 25 (6) ms in normal controls to 53 (18) ms in patients (P < 0.01). Intra-atrial mechanical dispersion (the time from the earliest to the latest onset of regional atrial motion around the atrioventricular ring) in the right atrium increased from 6 (2) ms in normals to 19 (2) ms in patients (P < 0.01), but it remained unchanged in the left atrium (6 (2) ms in normal controls v 7 (2) ms in patients, P > 0.05). Peak atrial shortening rate was not different between the two groups. Differences of atrial electromechanical activity between the two groups were also reflected on Doppler echocardiogram and apexcardiogram. CONCLUSIONS: Right atrial appendage pacing disturbs the normal coordinate sequence of right atrial mechanical activity and leads to a striking and variable increase in intra-atrial conduction time as well as in interatrial conduction time. Left atrial contraction remains synchronous although the timing of the start of its contraction was delayed. These values can be determined in individual patients to allow optimal setting of DDD pacemakers.

Aged↗
PubMed1995

Early diastolic left ventricular inflow pressures in normal subjects and patients with dilated cardiomyopathy. Reconstruction from pulsed Doppler echocardiography.

OBJECTIVE: To estimate early diastolic left ventricular inflow pressures in normal subjects and patients with dilated cardiomyopathy, and thus to assess the potential effect of restoring forces. METHODS: Early diastolic left ventricular inflow pressures were reconstructed using the ventricular blood as an accelerometer, by measuring velocity at 1 cm intervals within the left ventricle from mitral ring to apex by pulsed Doppler echocardiography, and differentiating the records to obtain the acceleration. Aortic component of second heart sound (A2) was used to fix relative timings. The local pressure gradient was determined from the acceleration at each level, and the total pressure drop during the acceleration (+ peak PD) and deceleration (- peak PD) phases of the filling interval were determined by summing the local increments. The total stroke volume (SV) at the left ventricular outflow tract and the mitral stroke distances (MSD) were also determined, using the time-velocity integral at mitral ring level. Effective flow orifice area was thus SV/MSD. Inflow jet width across the mitral valve was estimated by cross sectional colour Doppler flow mapping. PATIENTS: 32 patients with dilated cardiomyopathy with a dominant mitral E or summation wave, and 24 normal subjects of similar ages. RESULTS: Normal + peak PD was 3.9 (SD 0.7) v 7.4 (2.2) mm Hg in dilated cardiomyopathy (P < 0.01). Normal - peak PD was 2.5 (0.9) v 5.6 (2.8) mm Hg in cardiomyopathy (P < 0.01). Normal effective flow orifice area was 5.9 (1.3) v 1.9 (0.8) [range 0.9 approximately 3.7] cm2 in cardiomyopathy (P < 0.01). This corresponded to 71 (18)% of the end systolic cavity cross section in normals v 11 (6)% in dilated cardiomyopathy (P < 0.01). Normal cross sectional colour inflow jet width was 2.7 (0.3) v 1.5 (0.4) cm in cardiomyopathy (P < 0.01). The jet width correlated with flow width calculated from effective flow orifice area (r = 0.82, P < 0.01). CONCLUSIONS: (1) Total early diastolic positive and negative peak pressure drop are normally low, so that significant negative left ventricular pressures are not needed to explain normal resting early diastolic mitral flow velocities. (2) These low pressure drops are only possible with a large effective orifice area approaching end systolic left ventricular cavity area. (3) Atrioventricular pressure drops are much greater in dilated cardiomyopathy, where increased inflow accelerations are due to reduced effective flow orifice area. These disturbances will impair filling independently of any abnormality of relaxation or compliance.

Adult↗
PubMed1994

Effects of intermittent left bundle branch block on left ventricular diastolic function: a case report.

We investigated systolic and diastolic left ventricular function in a patient with an echocardiographically normal left ventricle and rate dependent left bundle branch block. Abnormal activation was associated with asynchronous left ventricular wall motion and secondary changes in filling pattern. The latter were similar to those seen in severe left ventricular disease. When the activation pattern reverted to normal, all of these abnormalities regressed. This case provides further evidence that abnormal activation can, on its own, cause left ventricular diastolic as well as systolic dysfunction.

Bundle-Branch Block↗
PubMed1994

Re-evaluation of normal splitting of the second heart sound in patients with classical left bundle branch block.

To study the mechanism of normal splitting of the second heart sound in patients with classical left bundle branch block, we investigated 43 such patients and 15 normal controls, using electro-, phono- and echo-cardiography and comparing the relative timing of mechanical activity in the two ventricles. The splitting of the second heart sound is reversed in only two-thirds of the patients and normal in remaining one-third. Comparing patients with and without reversed splitting, there are no significant differences in left ventricular cavity size, heart rate, pre-ejection period and the distribution of age, gender, or aetiology. QRS duration is longer (P < 0.01) in patients with reversed splitting. Diastolic events of the left ventricle do not differ between groups. The onset of the left ventricular free wall motion is delayed compared with normal by a similar extent in the two groups. In patients with normal splitting, the onset of the right ventricular wall motion is also delayed, both with respect to normal and to those with reversed splitting to an extent similar to that seen in classical right bundle branch block. Normal splitting of the second heart sound associated with an electrocardiographic pattern of left bundle branch block therefore suggests bilateral block. This combination can be documented from the precise timing of the movement of the two ventricles by M-mode echocardiography and identified by simple auscultation.

Aged↗