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Biomedical subjects

L L Yang

Publications and source records attributed to L L Yang.

At least 37 records · Page 2Linked to original sources
PubMed2000

Drug utilization pattern of antiepileptic drugs and traditional Chinese medicines in a general hospital in Taiwan - a pharmaco-epidemiologic study.

OBJECTIVE: Studies on antiepileptic drug utilization are important for the optimization of drug therapy and drug control. The present study was to evaluate the drug utilization pattern of standard antiepileptic drugs and traditional Chinese medicines (TCMs) in the treatment of different types of epilepsy in a general hospital in Taiwan. METHOD: The epileptic patients under antiepileptic drug treatment at Veterans General Hospital-Taipei were considered in the analysis. Current diagnosis was obtained by the neurologist in charge of the patient. All patients were interviewed by standard questionnaire designed to provide specific information on the types of antiepileptic drugs and details of their use. The questionnaire also sought to determine whether TCMs were used, and whether patients were using TCMs in combination with hospital standard treatment. The results were analysed by descriptive statistics. RESULTS: 729 patients with epilepsy definitely diagnosed were analysed in the study. 445 patients (61.04%) were prescribed with one antiepileptic drug. Combinations of two antiepileptic drugs were prescribed to 261 patients (35.80%), and combinations of three or more antiepileptic drugs to 23 patients (3.16%). A total of 1039 antiepileptic drugs was prescribed, corresponding to an average 1.42 drugs per patient. The most frequently prescribed antiepileptic drug was carbamazepine (56.93%), followed by phenytoin (31.96%), valproate (30.73%) and clonazepam (14.13%). Among the 729 epileptic patients, 83.68% used standard antiepileptic drugs alone, 16.32% used antiepileptic drugs in combination with TCMs. CONCLUSION: Monotherapy is the type of therapy most frequently used in all types of seizures. The selection of antiepileptic drugs is based on efficacy for specific seizure types and epileptic syndromes. The most frequently prescribed antiepileptic drug was carbamazepine, followed by phenytoin, valproate and clonazepam. As some of the patients used TCMs for treatment of epilepsy even when scientific medicine has been provided, further studies on the possible interactions between TCMs and antiepileptic drugs are in progress.

Adult↗
PubMed2000

Lack of pharmacokinetic interaction between valproic acid and a traditional Chinese medicine, Paeoniae Radix, in healthy volunteers.

BACKGROUND AND OBJECTIVE: In addition to the standard antiepileptic drugs, traditional Chinese medicines (TCMs) are used for the treatment of epilepsy in oriental countries. The interactions between antiepileptic drugs and TCMs represent a potential problem in clinical application. Because valproic acid (VPA), one of the most widely prescribed antiepileptic drugs, may be administered concomitantly with Paeoniae Radix (PR), one of the famous TCMs, in some epileptic patients, the present study was conducted to evaluate the influences of PR on the pharmacokinetics of VPA. METHOD: The pharmacokinetics of VPA were investigated in a randomized, open-label, two-way crossover study. Six healthy volunteers received the following treatments in a crossover design: (i) 1.2 g extract powder of Paeoniae Radix once daily for 7 days and one 200 mg VPA gastro-resistant tablet on day 7 and (ii) one 200 mg VPA gastro-resistant tablet alone on day 7. Serial plasma samples were obtained on day 7. Total and free (unbound) VPA plasma concentrations were determined by fluorescence polarization immunoassay (FPIA). Safety measures included laboratory tests (haematology, serum chemistry and urinalysis) and adverse event monitoring. Statistical comparisons of pharmacokinetic parameters were performed with the Student paired t-test. RESULTS: Overall clinical safety was satisfactory. The mean maximum plasma concentration of VPA was attained at within 6 h after oral administration of VPA alone and 3-4 h after oral administration of VPA in combination with PR. The plasma level of VPA declined with a half-life of 11.71 and 11.91 h, respectively. No statistically significant difference was obtained in any of the pharmacokinetic parameters (Tmax, Cmax, AUC, t1/2, MRT, CL/F and Vd/F) of VPA between the two treatments. Also, there was no significant difference in the protein binding rates of VPA. CONCLUSION: PR did not significantly affect the absorption, distribution, metabolism and elimination of VPA in healthy volunteers.

Administration, Oral↗
PubMed2000

Perilla citriodora from Taiwan and its phytochemical characteristics.

Perilla citriodora Nakai, the wild species of Perilla, was collected from Taiwan and its essential oil analyzed. GC-MS analysis of its oil showed that it has a novel composition of limonene (23.5%) and elemicin (17.8%). In Japanese Perilla, a monoterpene (limonene) and a phenylpropanoid (elemicin) have not been detected in the same plant. To compare the sequence similarity of a secondary metabolic enzyme between P. frutescens and P. citriodora, the nucleic acid sequence of the limonene synthase in this P. citriodora was analyzed using the reverse transcript-polymerase chain reaction (RT-PCR) method. Primers for PCR were designed by employing the known sequence of the limonene synthase cloned from P. frutescens. It was found that the limonene synthase in P. citriodora and that in P. frutescens share a high sequence identity, probably indicating that both enzymes evolved from a common ancestor.

Amino Acid Sequence↗
PubMed2000

[Determination of simvastatin in human plasma by high performance liquid chromatography].

Simvastatin is widely used in the treatment of hypercholestero-lemia. Recently, it was reported that it is also effective in reducing lethality in coronary heart disease. A simple and sensitive reversed-phase liquid chromatographic method has been developed and validated for the analysis of simvastatin in human plasma. Simvastatin and internal standard lovastatin in plasma were extracted with cyclohexane-dichloromethane (3.5:1, V/V), and then measured by HPLC using a Lichrospher C18 column as stationary phase and an acetonitrile-water (70:30, V/V) mixture as mobile phase. The flow rate was 1.2 mL/min. Simvastatin was quantified by UV at 237 nm. The calibration curve showed a good linearity in the mass concentration range of 0.25-50.0 micrograms/L. The regression equation is: Y = 0.0364 rho + 0.00583, r = 0.9998. Intra-day and inter-day coefficients of variation of assay for simvastatin in plasma < 7.94% and < 8.58%, respectively. The recoveries of simvastatin were > 93.3%. The method has been used to determine simvastatin in plasma from 12 healthy male volunteers.

Adult↗
PubMed2000

[Determination of bromhexine in plasma by gas chromatography-electron capture detection and pharmacokinetic studies].

This paper reports a gas chromatography-electron capture detection(GC-ECD) method for the study of pharmacokinetics of bromhexine in healthy human body. A2 m x 3 mm i.d. silanized glass column packed with 5% SE-30 was used. The carrier gas was nitrogen. The internal standard was 5-chloro-2-amino-diphenyl ketone. After NaH2PO4-Na2HPO4 buffer (pH 6.0) being added, the plasma was extracted with n-hexane-dichloromethane (9:1, V/V). A good linearity was obtained from 1.0 microgram/L to 50.0 micrograms/L of bromhexine in human plasma, r = 0.9994. The detection limit of bromhexine in plasma was 0.5 microgram/L. The average recovery was 97.5%. The pharmacokinetics of bromhexine was determined by this method after a single oral dose of 8 mg bromhexine capsule given to each of 8 volunteers. The results showed that the plasma concentration-time courses conformed to one compartment model. The established GC-ECD method is a good method for the determination of bromhexine in human plasma. The method is rapid, simple, precise and sensitive.

Bromhexine↗
PubMed1999

Pharmacokinetic study of paeoniflorin in mice after oral administration of Paeoniae radix extract.

Quantification of paeoniflorin, the principal bioactive component of Paeoniae radix, in mice plasma following oral administration of Paeoniae radix extract was achieved by using a simple and rapid high-performance liquid chromatographic method. The calibration curve for paeoniflorin was linear (r2 = 0.998) over the concentration range 10-200 ng/ml. The coefficients of variation of intra- and inter-day assays were 15.04, 7.31, 6.14, 6.55, 6.63% and 12.71, 6.07, 3.61, 5.51, 4.52% at concentrations of 10, 60, 100, 160, 200 ng/ml, respectively. The recoveries of paeoniflorin from mice plasma were found to be 74.49, 76.83, 80.38 and 80.56% for concentrations of 30, 80, 120 and 160 ng/ml, respectively. The plasma concentration-time curves were fitted with mean terminal half-lives (t(1/2)) of 94.16 min.

Animals↗
PubMed1999

Human G protein-coupled receptor GPR-9-6/CC chemokine receptor 9 is selectively expressed on intestinal homing T lymphocytes, mucosal lymphocytes, and thymocytes and is required for thymus-expressed chemokine-mediated chemotaxis.

TECK (thymus-expressed chemokine), a recently described CC chemokine expressed in thymus and small intestine, was found to mediate chemotaxis of human G protein-coupled receptor GPR-9-6/L1.2 transfectants. This activity was blocked by anti-GPR-9-6 monoclonal antibody (mAb) 3C3. GPR-9-6 is expressed on a subset of memory alpha4beta7(high) intestinal trafficking CD4 and CD8 lymphocytes. In addition, all intestinal lamina propria and intraepithelial lymphocytes express GPR-9-6. In contrast, GPR-9-6 is not displayed on cutaneous lymphocyte antigen-positive (CLA(+)) memory CD4 and CD8 lymphocytes, which traffic to skin inflammatory sites, or on other systemic alpha4beta7(-)CLA(-) memory CD4/CD8 lymphocytes. The majority of thymocytes also express GPR-9-6, but natural killer cells, monocytes, eosinophils, basophils, and neutrophils are GPR-9-6 negative. Transcripts of GPR-9-6 and TECK are present in both small intestine and thymus. Importantly, the expression profile of GPR-9-6 correlates with migration to TECK of blood T lymphocytes and thymocytes. As migration of these cells is blocked by anti-GPR-9-6 mAb 3C3, we conclude that GPR-9-6 is the principal chemokine receptor for TECK. In agreement with the nomenclature rules for chemokine receptors, we propose the designation CCR-9 for GPR-9-6. The selective expression of TECK and GPR-9-6 in thymus and small intestine implies a dual role for GPR-9-6/CCR-9, both in T cell development and the mucosal immune response.

Antibodies, Monoclonal↗
PubMed1999

Inducible nitric oxide synthase inhibitor of the Chinese herb I. Saposhnikovia divaricata (Turcz.) Schischk.

L-Arginine derived nitric oxide (NO) and its derivatives, such as nitrogen dioxide and peroxynitrite, play a role in inflammation and also possibly in the multistage process of carcinogenesis. Four furanocoumarins and eight chromones isolated from the dried root of Saposhnikovia divaricata (Fang Feng in Chinese) and evaluated for their effects on the synthesis of NO induced by lipopolysaccharide (LPS) in macrophage cell line RAW 264.7. The inhibition of nitrite production, as an index for NO released from the macrophage cells, was quantitatively analyzed by Griess reaction. The results showed that imperatorin and deltoin are potential NO production inhibitor, and their IC50 values for inhibition of nitrite production were 17.3 and 11.6 microg/ml, respectively. Western-blot analysis demonstrated that iNOS enzyme activity was not inhibited by treatment with imperatorin or deltoin, but revealed that both compounds inhibited the expression of the iNOS protein.

Animals↗
PubMed1999

Antitumor activity of four macrocyclic ellagitannins from Cuphea hyssopifolia.

We evaluated the antitumor activities of four macrocyclic hydrolyzable tannin dimers, cuphiin D1, cuphiin D2, oenothein B and woodfordin C isolated from Cuphea hyssopifolia (Lythraceae). All significantly inhibited the growth of the human carcinoma cell lines KB, HeLa, DU-145, Hep 3B, and the leukemia cell line HL-60, and showed less cytotoxicity than adriamycin against a normal cell line (WISH). All four compounds inhibited the viability of S-180 tumor cells in an in vitro assay and an in vivo S-180 tumor-bearing ICR mice model. Oenothein B demonstrated the greatest cytotoxicity (IC50 = 11.4 microg/ml) against S-180 tumor cells in culture, while cuphiin D1 resulted in the greatest increase in survival on S-180 tumor-bearing mice (%ILS = 84.1%). Our findings suggest that the antitumor effects of these compounds are not only related to their cytotoxicity on carcinoma cell lines, but also depended on a host-mediated mechanism; they may therefore have potential for antitumor applications.

Animals↗
PubMed1999

Long-term results of corneal graft survival in infants and children with peters anomaly.

OBJECTIVE: To determine the long-term results of corneal graft survival after penetrating keratoplasty for Peters anomaly and to identify risk factors for graft failure. DESIGN: Noncontrolled interventional case series: a single-center retrospective review of a consecutive surgical series. PARTICIPANTS: The records of all children 12 years of age or younger who underwent penetrating keratoplasty for Peters anomaly between January 1971 and December 1992 were reviewed. All study eyes had completed a minimum of 3 years of follow-up from the date of first keratoplasty and had undergone most of their corneal surgery at Emory University. INTERVENTION: Characteristics of the recipient, the eye, the donor, and the surgical procedure were analyzed for their influence on survival of the first graft. Survival probabilities were estimated using the Kaplan-Meier method. Multivariate regression analysis was performed to estimate relative risks and adjusted survival probabilities. MAIN OUTCOME MEASURE: Graft clarity. RESULTS: One hundred forty-four penetrating keratoplasties were performed in 72 eyes of 47 patients. The median age at first keratoplasty was 4.4 months. The median follow-up was 11.1 years. Fifty-four percent of eyes received one graft, 18% received two grafts, and 28% received three or more grafts. The overall probability of maintaining a clear first graft was 56% at 6 months, 49% at 12 months, 44% at 3 years, and 35% at 10 years. The probability of second or subsequent grafts surviving for 3 years was less than 10%. Thirty-nine percent of eyes had a clear graft at the time of review; 36% of eyes had a clear first graft. Multivariate analysis identified disease severity, donor cornea size, coexisting central nervous system abnormalities, and quadrants of anterior synechiae as the strongest risk factors for graft failure. Supplemental multivariate analysis, restricted to observable preoperative variables, identified stromal vessels, total limbal opacification, and preoperative glaucoma as independent preoperative predictors of graft failure. Allograft rejection was the most frequently identified cause of graft failure. Major complications after keratoplasty were phthisis, retinal detachment, cataract, and glaucoma. CONCLUSIONS: The overall long-term probability of maintaining a clear graft after initial penetrating keratoplasty for Peters anomaly is 35% +/- 0.06%, with subsequent grafts rarely surviving. Eyes with severe disease, larger donor corneas, coexisting central nervous system abnormalities, and anterior synechiae have significantly poorer outcomes than eyes without these factors. These data should be carefully considered before recommending corneal transplantation for Peters anomaly, particularly after previous graft failure.

Anterior Eye Segment↗
PubMed1997

Monitoring of blood catecholamines by microdialysis and microbore LC with a dual amperometric detector.

The accuracy of in vivo microdialysis for monitoring blood catecholamines and their metabolites in Lan-Yu mini-pigs was evaluated. To prevent blood clots and irritation, a microdialysis probe was secured in a Y-shaped tube. The tube was connected to an arterio-venous shunt, in a mini-pig, for in vivo experiments. Perfusates were injected onto a microbore LC equipped with a dual electrochemical detector (the upstream electrode was set at an oxidizing potential and the downstream electrode was set at a reducing potential. The typical large offscale peak or interfering peaks on the anodic chromatograms were mostly eliminated on the cathodic chromatograms, thereby providing reliable measurements of early eluters. Early eluates, such as norepinephrine and epinephrine, with reversible redox behaviour could be detected at the downstream reducing electrode. A comparison of the present method and a conventional blood-drawing method showed good correlation (r = 0.775-0.983 for all analytes).

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

[Determination of isosorbide-5-mononitrate in plasma by GC-ECD and study on its pharmacokinetics in ten volunteers].

A rapid, accurate and sensitive gas chromatographic method was developed for the determination of isosorbide-5-mononitrate(5-ISMN) in 0.5 ml plasma. The instrument was equipped with 5% SE-30 glass packed column (2 m x 3 mm) and electron-capture detector. Isosorbide dinitrate (ISDN) was used as internal standard. The plasma was extracted with a mixture of ethyl ether and n-hexane (4:1) to give mean recoveries of 100.1% of 5-ISMN. The extracts reacted with trifluoroacetic anhydride and the derivatives were analyzed. The calibration curves were linear over a wide range of concentrations (20-800 ng.ml-1), and the detection limit of 5-ISMN was 2.0 ng.ml-1. The precisions (RSD%, n = 5) of within-day and day-to-day were less than 4% and 6.5%, respectively. The pharmacokinetic characteristics of 5-ISMN in ten human volunteers after a single oral dose of 20 mg 5-ISMN were investigated. The concentration-time curve was fitted to a one-compartment model.

Adult↗
PubMed1996

New dual electrochemical detector for microbore liquid chromatography. Determination of dopamine and serotonin in rat striatum dialysates.

A new type of liquid chromatographic (LC) dual thin-layer amperometric detector for the simultaneous measurement of trace levels of dopamine and serotonin in microdialysates is described. The concentrations of these analytes in rat dialysates are usually in the sub-nanomolar concentration range (typically, 0.10-5.00 pg in 5-microl dialysates). With this dual electrode, a glass-lined microbore column provides excellent sensitivity, selectivity, and separation. In addition, a three- to five-fold improvement in anodic current or cathodic responses over conventional dual electrodes in microbore LC can be achieved. Due to the irreversible electrochemical properties of some interference peaks, this dual electrode provides reliable measurement of dopamine based on the cathodic signal. The detection limit (signal-to-noise ratio = 3) of this assay is 0.02 pg per injection for dopamine or serotonin. This new dual electrode allows the simultaneous measurements of basal dopamine and serotonin in rat striatum dialysates without the use of re-uptake inhibitors in perfusion medium.

Animals↗
PubMed1996

Congenital entropion and congenital corneal ulcer.

PURPOSE: We studied a case of corneal ulceration in utero from lower eyelid entropion. METHODS: A 3-week-old male infant was referred for examination of a left corneal ulcer that was present at birth and unresponsive to antibiotics. RESULTS: Examination disclosed a lower eyelid entropion that was treated surgically by a nonincisional method, leaving a central leukoma after re-epithelialization. CONCLUSION: Congenital lower eyelid entropion should be included in the differential diagnosis of congenital corneal opacities.

Corneal Opacity↗
PubMed1995

Determination of human plasma biogenic amines and their metabolites using liquid chromatography with a dual-channel electrochemical detector.

BACKGROUND: Measurement of biogenic amines and their metabolites in plasma has been used for decades to explore the pathophysiology of neuropsychiatric disorders or to examine the mode of action of psychotropic medications. Many advantages of ultrafiltration and high-performance liquid chromatography (HPLC) in assaying human plasma content have been described in our previous study. METHODS: The present HPLC assay, applying a dual-channel electrochemical detector, provides an additional reliable measurement or confirmation of peaks by identifying each peak retention capacity factor and its current ratio in the dual-channel detector. Simultaneous measurements of plasma serotonin, catecholamines and their metabolites by ultrafiltration and microbore HPLC technique is applied to evaluate moclobemide and fluoxetine therapy in patients with major depression. RESULTS: This present HPLC method provides highly specific detection, free from interference by the large offscale peak of plasma ultrafiltrates. Isocratic separation of all analytes by a microbore column is achieved within 15 mins. The detection limit (signal-to-noise ratio = 3) of this method is about 0.2-0.5 pg per injection for all analytes. In addition, the required volume of plasma samples is only 100 microliters. CONCLUSIONS: This rapid, simple and sensitive method for the measurement of human plasma serotonin, catecholamines and their metabolites can be used as a clinical or biomedical research tool. Blood loss is minimal in the present assay, especially in repeated blood sampling for pharmacokinetic studies.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Rapid assay of the monoamine content in small volumes of rat plasma.

A method for the simultaneous measurement of serotonin catecholamines, and their metabolites in rat plasma by ultrafiltration and microbore liquid chromatography with electrochemical detection (LC-ED) in small volumes is established. Prior to the LC assay, sixteen plasma ultrafiltrates are readily prepared within 30 min in the present study. The present method, applying a dual-electrode detection technique, provides an additional reliable assignment or measurement of peaks by identifying the peaks on the basis of their redox ratios. In addition, the important early-eluting peaks and interfering peaks are eliminated in the cathodic chromatogram resulting in a reliable measurement of norepinephrine, epinephrine, and 3,4-dihydroxyphenylacetic acid. Isocratic separation of serotonin, catecholamines, and their metabolites by a microbore column is achieved within 15 min. Hence, theoretically, over 90 analyses can be performed in a working day. The limit of detection (signal-to-noise ratio = 3) of this method is ca. 0.2-0.5 pg per injection for all analytes. The required volume of the plasma samples can be less than 100 microliters. Hence, the remainder of the plasma sample can be analysed for other substances. This rapid, simple, and sensitive method can thus be used as a research tool in the simultaneous measurement of rat plasma serotonin, catecholamines, and their metabolites.

Animals↗
PubMed1994

A dimeric hydrolysable tannin from Camellia oleifera.

Camellioferin A, a new dimeric ellagitannin, was isolated, together with 13 known tannins, including camellins A and B, from Camellia oleifera. The structure of the new tannin elucidated by spectroscopic methods.

Circular Dichroism↗