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Biomedical subjects

S X Chen

Publications and source records attributed to S X Chen.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effects of tannins from Geum japonicum on the catalytic activity of thrombin and factor Xa of blood coagulation cascade.

Bioassay-guided fractionation of the MeOH extract of the whole plant of Geum japonicum led to the isolation of seven known tannins. They were identified by spectroscopic methods as penta-O-galloyl-beta-glucoside (1), pedunculagin (2), 2, 3-(S)-hexahydroxydiphenoyl-D-glucose (3), tellimagrandin II (4), 2, 6-di-O-galloyl-D-glucose (5), casuariin (6), and 5-desgalloylstachyurin (7). Compounds 1, 2, 4, 6, and 7 showed potent anticoagulant activity by significantly prolonging the clotting of rabbit plasma. The inhibitory effect of 2 was competitively directed against thrombin. Its IC50 values for inhibition of the enzymatic activity of thrombin on synthetic substrate and fibrinogen were 0.18 and 0.15 microM, respectively. On the other hand, compounds 1, 4, 6, and 7 are mixed noncompetitive inhibitors of thrombin. Their IC50 values for inhibition of fibrinogen hydrolysis were twofold to sevenfold lower than those for the inhibition of synthetic substrate hydrolysis. Factor Xa was competitively inhibited by compounds 1, 2, 4, 6, and 7. The phenolic hydroxyl groups of the active tannins appear to play an important role in their inhibitory effect on the enzymes.

Animals↗
PubMed1998

Preconditioning enhances myocardial protection in patients undergoing open heart surgery.

To date, ischemic preconditioning is regarded as the most powerful form of endogenous myocardial protection. For the purpose of surgical myocardial protection, a few clinical studies have investigated the effects of ischemic preconditioning in conjunction with hypothermia or blood cardioplegia during open heart surgery, but the results were controversial. We now tested the hypothesis that preconditioning improves myocardial protection in patients undergoing cold crystalloid cardioplegic arrest. 36 patients needing mitral prosthetic valve replacement for rheumatic heart disease were studied. Patients were evenly divided into two groups at random. Preconditioning was elicited by two cycles of 3 minutes ischemia by occlusion of vena cava and aortic cross-clamping followed by 2 minutes reperfusion under cardiopulmonary bypass. All hearts were arrested using 4 degrees C St. Thomas' Hospital solution before the intracardiac operative program. Myocardial protective effects were mainly assessed by electrocardiac activities, leakage of myocardial enzymes, myocardial contractility, and early postoperative recovery. The results indicated that there was a significant reduction of ST-segment shifting (ST-segment elevation, 0.07 +/- 0.02 vs 0.22 +/- 0.07 mV, p < 0.05, at 4 hours post reperfusion) and smaller release of creatine kinase-MB (87 +/- 11.5 vs 143 +/- 17.2 IU/L, p < 0.05, at 12 hours post reperfusion) in the preconditioning group. Preconditioning also enhanced myocardial contractility (dp/dtmax = 1490 +/- 75 vs 1280 +/- 88 mmHg/sec, at 30 minutes post reperfusion, p < 0.05) and promoted early postoperative recovery. The present study suggests that ischemic preconditioning reduces ischemia-reperfusion injury in human hearts even when combined with cold crystalloid cardioplegia.

Adult↗
PubMed1998

Purification of alpha 1 proteinase inhibitor from human plasma fraction IV-1 by ion exchange chromatography.

BACKGROUND AND OBJECTIVES: Alpha-proteinase inhibitor (PI) protects the lungs from proteolytic damage caused by elastase and can be used to treat congenital emphysema. We describe an improved method of purification of alpha 1 PI from redissolved fraction IV-1 paste. MATERIALS AND METHODS: The process used dimethylaminoethyl anion exchange chromatography, sulfopropyl cation exchange chromatography, virus inactivation by dry heat, and tri-n-butyl-phosphate/cholate treatment, followed by a second strong cation exchange chromatography. Optimizations of loading conditions for ion exchange chromatography at small scale (20-60 ml of suspension) are described. Virus inactivation was adjusted to provide the best yield of alpha 1 PI consistent with effective inactivation. The process has been effectively scaled up. RESULTS: The final product was approximately 90% pure by SDS-PAGE, with a 60-70% yield from starting fraction IV-1 paste. The process has been characterized by methods including nonreduced SDS-PAGE, alpha 1 PI inhibition assay, and biuret protein assay. CONCLUSION: The method described is an effective way of preparing large quantities of alpha 1 PI from fractionated plasma.

Anions↗
PubMed1997

Preconditioning improves myocardial preservation in patients undergoing open heart operations.

BACKGROUND: Our previous work has shown that preconditioning can promote the recovery of cardiac function in patients having an open heart procedure. Because preconditioning is regarded as the most powerful form of endogenous myocardial protection, we tested the hypothesis that preconditioning protects against myocardial ischemia-reperfusion injury in patients undergoing prolonged cold crystalloid cardioplegic arrest. METHODS: Thirty patients who had rheumatic heart disease and required both aortic and mitral valve replacement were studied. Patients were randomly divided into two equal groups. Preconditioning was accomplished using two cycles of 2-minute occlusion of the vena cava and aorta followed by 3 minutes of reperfusion under cardiopulmonary bypass. All hearts were arrested with 4 degrees C St. Thomas' Hospital cardioplegic solution. Myocardial protective effects were assessed by changes in myocardial levels of adenosine triphosphate, electrocardiographic activity, leakage of myocardial enzymes, and myocardial contractility. RESULTS: The adenosine triphosphate content in ischemic myocardium was higher in the preconditioning group than in the control group (p < 0.05 90 minutes after ischemia), and there was a significant reduction in release of the myocardial-specific isoenzyme of creatine kinase in the preconditioning group. Preconditioning improved the recovery of myocardial contractility (first derivative of left ventricular developed pressure, 1,490 +/- 102 mm Hg/s versus 1,250 +/- 97 mm Hg/s 30 minutes after reperfusion; p < 0.05), and there was also a protective effect on electrocardiographic activity. CONCLUSIONS: Our results suggest that ischemic preconditioning protects the myocardium in humans from the severe ischemia-reperfusion injury produced after prolonged arrest with cold crystalloid cardioplegia.

Adenosine Triphosphate↗
PubMed1997

Maintaining a near zero-order drug delivery from minidose reservoirs: simultaneous drug diffusion and binary vehicle evaporation.

The purpose of this study was to develop a new design for transdermal system that provides a nearly constant drug delivery rate for the desired period of time in the absence of a large excess of drug in the donor reservoir. Simultaneous drug diffusion and aqueous binary vehicle evaporation has been investigated as a means of maintaining constant drug delivery from minidose reservoirs. Benzocaine was used as the model drug and water-ethanol mixtures as the binary vehicles. Benzocaine is much more soluble in ethanol than in water. Simultaneous diffusion-evaporation experiments were conducted using the water-ethanol mixture saturated with benzocaine as the minidose-reservoir. The reservoir vehicle was allowed to evaporate through a permselective membrane so as to maintain drug saturation in the vehicle even though the drug mass in the donor reservoir was constantly decreasing. Saturation activity of drug is maintained during donor depletion of drug by the selective loss of alcohol from the donor solvent, which concomitantly lowers the solubility. The superiority of the evaporable binary vehicle over a conventional sealed system was demonstrated by achieving near zero-order drug delivery with minimum drug remaining. A theoretical model was developed to predict drug flux, drug amount delivered, reservoir solvent volume and composition, and drug solubility during the two simultaneous processes of drug release and preferential solvent evaporation. Experimental data are in good agreement with theoretical calculations.

Benzocaine↗
PubMed1997

[Effects of tetramethylpyrazine on platelet functions of advanced cases of lung carcinoma].

OBJECTIVE: To explore the role of hypercoagulation in the metastasis of carcinoma. METHODS: The effect of Tetramethylpyrazine (TTMP) on platelet functions among the 25 advanced cases of lung carcinoma, and 26 matched control subjects were investigated in the study. Their ages varied from 31-86 years (mean 58.2) in lung carcinoma group (13 male, 12 female) and 36 to 61 (mean 52.9) in the control group (16 male, 10 female). The pathologic types were as follows: 7 cases of squamous cell cancer, 12 adenocarcinoma, 2 small cell carcinoma and 4 undistinguished type. The TNM stage revealed 14 cases in stage IIIa, 3 in stage IIIb and 8 in stage IV. The site of metastasis included mediastinal lymph node, pleura, supraclavicular lymph node, brain, spine, costa, skin and pericardium. The levels of plasma TXB2, 6-keto-PGF1 alpha, VIII:C, vWF, AT-III:a, AT-III:Ag, Fg and blood PAdT, PAgT were measured before and after the intravenous infusion of 80 mg TTMP in patients with lung carcinoma. RESULTS: The levels of TXB2, 6-keto-PGF1 alpha, VIII:C, vWF and Fg in lung carcinoma group were significantly elevated, while the levels of PAdT was greatly decreased, compared with the control group, no significant differences in levels of PAgT, AT-III:a and AT-III:Ag were found between the two groups. After the infusion of TTMP the levels of PAdT, PagT, VIII:C, dWF and Fg were decreased significantly, while TXB2, 6-keto-PGF1 alpha, AT-III:a and AT-III:Ag remained unchanged. CONCLUSIONS: TTMP inhibits the adhesion and aggregatory functions of blood platelet and the activity of coagulation factors. It might be one of the mechanisms of TTMP's antimetastasis of lung carcinoma.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

[Therapeutic effect of kangke injection on viral myocarditis and its anticoxsackie virus mechanism].

OBJECTIVE: To assess the efficacy of Kangke Injection in treating viral myocarditis. METHODS: Kangke Injection is the effective ingredient extracted from Radix Sophora flavescens (RSF). Seventy-six cases of virus myocarditis suffering from the continuous positive Coxsackie B virus ribose nucleic acid-polymerase chain reaction (CBVRNA-PCR) in blood, their peak value in blood was determined by high performance liquid chromatography (HPLC) and compared with 50 cases treated by glucose-insulin-potassium chloride (GIK). RESULTS: The clearance rate of CBVRNA-PCR and RSF was dose-dependent. The effective rate of RSF on palpitation, chest distress, dispnea was 96.02%, and that of arrhythmia was 100%, all of them were better than those of control. After RSF therapy, the parameters of heart function of ejection fraction (EF), stroke volume (SV), cardiac output (CO), and cardiac index (CI) elevated significantly (P < 0.01), left ventricular mass (LVM) and left ventricular mass index (LVMI) were decreased statistically significantly, while after 5 month therapy, the anti-Coxsackie group B virus neutralizing antibodies of RSF group was returned to normal titer, natural killer (NK) cell activity elevated, P < 0.01. CONCLUSION: RSF was an effective substance for regressing the "Pathologic status" of viral myocarditis.

Adolescent↗
PubMed1996

Active constituents against HIV-1 protease from Garcinia mangostana.

The ethanol extract of Garcinia mangostana L. (Guttiferae) showed potent inhibitory activity against HIV-1 protease. The activity-guided purification of the extract resulted in the isolation of two active, known compounds. The chemical structures of the isolated compounds were established by spectroscopic analyses as mangostin (IC50 = 5.12 +/- 0.41 microM) and gamma-mangostin (IC50 = 4.81 +/- 0.32 microM). The type of inhibition by both compounds is noncompetitive.

Amino Acid Sequence↗
PubMed1996

[Identification of the origin of 7q+ marker chromosome in a mental retard patient].

The present chromosome-specific and chromosome-band-specific probe pools constructed by the technique of human chromosome microdissection and PCR were taken as painting probes. Using the forward chromosome painting and chromosome screening method, we had identified a chromosome additional fragment of a 7 q+ marker chromosome in a patient originated from 3 q 26-->3 qter, and ascertained the patient's karyotype was 46, XX, -7, + der (7) t (7;3) (7 pter-->7 q 32::3 q 26-->3 qter). Applying this strategy, we can identify the origin of marker chromosomes fastly and effectively.

Child↗
PubMed1994

[Pharmacokinetics of matrine in healthy volunteers].

A sensitive high performance liquid chromatographic analytical method was established for determining the concentration of matrine in human serum. The recovery of matrine was 99.1-102.2%. The RSD (%) in within-day and between-days were no more than 6%. The calibration curve was linear in the range from 1.25 micrograms.ml-1 to 40.0 micrograms.ml-1 with r = 0.9997. The serum drug concentration-time curve after iv infusion with a dose of 6 mg.kg-1 in 100 ml glucose solution for 8 healthy volunteers was fitted to a 2-compartment open model. The excretion of unchanged drug in urine was 52.75% of the dose in 32 h and the ClR was 143.79 ml.min-1.

Adult↗
PubMed1994

[Pharmacokinetics and pharmacodynamics of slow release tablet of diltiazem in hypertensive patients with various renal functions].

Twenty hypertensive patients were equally divided into 2 groups: A) with normal renal function (NRF) and B) with impaired renal function (IRF) according to creatinine clearance, blood urea nitrogen and creatinine levels. The pharmacokinetic and pharmacodynamic effects of diltiazem (Dil, 90 mg, bid x 7 d, p.o.) were studied. The pharmacokinetic parameters in IRF patients (Ka 0.7 +/- 0.2 h-1, T 1/2e 3.7 +/- 0.7 h, Cmax1 45 +/- 4 ng.ml-1, Tmax1 3.1 +/- 0.4 h) did not differ from those in NRF patients (0.7 +/- 0.5 h-1, 4.1 +/- 1.3 h, 41 +/- 5 ng.ml-1 and 3.4 +/- 0.4 h, P > 0.05). Antihypertensive efficacy of Dil in patients with IRF was similar to that in those with NRF, and the hypotensive effect lasted over 24 h. The plasma Dil concentrations were strongly correlated with a decrease in BP in both groups. It was concluded that IRF did not affect the disposition of slow release Dil tablet under a steady state. No dosage adjustment of Dil is necessary in hypertensive patients with IRF.

Adult↗
PubMed1993

Purification and characterization of beta-structural domains of beta-lactoglobulin liberated by limited proteolysis.

Incubation of beta-lactoglobulin with immobilized trypsin at 5-10 degrees C results in a time-dependent release of several fragments of the core domain in yields approaching 15%. Digests were fractionated by ion-exchange chromatography with a Mono Q HR 5/5 column and analyzed after disulfide reduction by polyacrylamide gel electrophoresis in sodium dodecylsulfate. Three fragments with approximate molecular weights of 13.8, 9.6, and 6.7 kD were identified. The fraction from ion-exchange chromatography yielding the 6.7 kD fraction after disulfide reduction was further characterized because it was most homogeneous and gave the highest yield. The C-terminal cleavage site of the 6.7 kD core fragment appeared to be Lys100 or Lys101 as determined by C-terminal amino acid analysis. The exact masses, after reduction with dithiothreitol, are 6195 and 6926 as determined by laser desorption mass spectrometry, corresponding to residues 48-101 and 41-100. Prior to reduction, beta-lactoglobulin C-terminal residues 149-162 are connected to these core domain fragments as shown by C-terminal analysis and mass spectrometry. Structural studies indicate that these 7.9 and 8.6 kD core domain fragments released by immobilized trypsin retain much of their native structure. CD spectra indicate the presence of antiparallel beta-sheet structure similar to the native protein but the alpha-helix is lost. Spectra in the aromatic region indicate the existence of tertiary structure. Moreover, structural transitions in urea are completely reversible as measured by CD spectra, although the extrapolated delta GDH20 and the urea concentration at the transition midpoint are lower than for the native protein. The core domain fragments also display a pH-dependent binding to immobilized trans-retinal as does intact protein. A single endotherm is obtained for both core domain fragments and native protein upon differential scanning calorimetry, but again, the domain is less stable as indicated by a transition peak maxima of 56.9 degrees C as compared with 81.1 degrees C for native protein.

Amino Acid Sequence↗
PubMed1993

The effect of mangxiao (natrii sulphas) in the relief of stasis and swelling after implantation of cardiac pacer.

Sixteen patients with local stasis and swelling after implanting cardiac pacemaker were treated with Mangxiao (Natrii Sulphas) on the implanted local surface for 4-14 days. The effect was satisfactory. Reopening of the skin for the cleaning of the stasis and swelling and removal of the pacemakers could thus be avoided in these patients. The mechanism of action of Mangxiao in relieving stasis and swelling was studied preliminarily.

Administration, Topical↗
PubMed1993

Immunological status and pathology of coxsackie B viral myocarditis and dilated cardiomyopathy.

The changes in 15 cases of viral myocarditis and 28 cases of dilated cardiomyopathy were reported and compared, which were the pathological changes of endomyocardial biopsy; NK cells activity; % of peripheral T lymphocytes and its subsets determined by using OKT3,4,8 (OKT3-peripheral total lymphocytes; OKT4-helper cells; OKT8-suppressive cells) monoclonal antibody; values of immunoglobulin IgG, IgA, IgM; titer of coxsackie B antibody neutralization test. And a discussion on their relationship was included.

Adolescent↗
PubMed1992

[Pharmacokinetics and pharmacodynamics of diltiazem floating tablets].

Floating tablet is a new type of delayed-action preparations. The present study was aimed at pharmacokinetic and hemodynamic effects of diltiazem floating tablet in 8 healthy volunteers. Each subject received po 90 mg diltiazem floating and normal tablets in a crossover design. For floating tablets the T1/2 (6.4 +/- 4.4 h) and Cmax (56 +/- 23 ng.ml-1) were longer and lower than those of normal tablets (2.3 +/- 1.1 h and 96 +/- 30 ng.ml-1, P < 0.01), respectively. AUC of the 2 forms were similar, suggesting that they had same bioavailability. Diltiazem lowered the blood pressure of the subjects. Although there was no significant difference between the 2 formulations in maximal decreases of systolic and diastolic blood pressures, the duration of hypotension was longer with floating tablets than that with normal ones. There was a positive correlation between diltiazem concentration and its hypotensive action. Thus, administration of floating tablets twice a day may be effective in controlling the blood pressure of hypertensive patients.

Adult↗
PubMed1992

[Integrated traditional and Western medicine treatment of severe viral myocarditis].

33 patients divided into 2 groups for treatment. Group A (18 cases) early use of adrenal cortico-steroid treatment in combination with traditional Chinese medicine; group B (15 cases): early use of adrenal cortico-steroid treatment is combination with interferon, then compared the therapeutic effects of these 2 groups. The results showed that, in these 2 groups, the sinus-atrial block, atrial ventricular block, ventricular tachycardia, acute pump failure as well as the EKG changes were relieved and improved to the same degree. In group A, after therapy, the parameters of OKT3 (%) was elevated from 51 +/- 15.22 to 55.23 +/- 8.53; OKT4(%) was elevated from 30.06 +/- 11.47 to 47.32 +/- 10.87; ratio of OKT4/OKT8 was elevated from 1.11 to 1.53; all of their P values were < 0.01. NK cell activity was elevated from 8.36 +/- 3.75 to 13.08 +/- 5.77, P value < 0.05. In group B, the parameters of OKT3 (%) was elevated from 50.91 +/- 8.12 to 56.75 +/- 8.29; OKT4 (%) was elevated from 32. 55 +/- 6.78 to 45.13 +/- 10.85; ratio of OKT4/OKT8 was elevated from 1.00 +/- 0.21 to 1.37 +/- 0.16; P value < 0.05, < 0.05 and < 0.01 respectively. NK cell activity (%) was elevated from 8.20 +/- 3.08 to 14. 0.3 +/- 4.89, P value also < 0.01. Hence, not only in group A but also in group B, after therapy, the parameters of OKT3,4,8, OKT4/OKT8 and NK cell activity (%) were all improved. But there was no significant statistical difference between group A and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adams-Stokes Syndrome↗
PubMed1989

A clinical investigation with Holter's monitoring of the antiarrhythmic effect of adonisidum.

The authors studied 24 cases of refractory premature beats by giving 0.1 adonisidum twice daily with Holter's monitoring. It was found that adonisidum was effective in 12 cases (P less than 0.001), or 50%. In another 8 patients adonisidum or mexiletine alone were ineffective for premature beats. However, when these patients were treated with both mexiletine and adonisidum, they responded with no exception (P less than 0.001). All 7 cases monitored with one hour Holter recording responded to adonisidum (P less than 0.001). As adonisidum tends to slow the heart rate, it is especially indicated for patients suffering from premature beats with increased heart rate, and should be used with caution in cases with slow heart rate or A-V block.

Adolescent↗