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Biomedical subjects

Y L Chang

Publications and source records attributed to Y L Chang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Quinoline alkaloids and other constituents of Melicope semecarpifolia with antiplatelet aggregation activity.

Three new quinoline alkaloids, 2-acetylevolitrine (1), 2-acetylpteleine (2), and semecarpifoline (3), along with 26 known compounds were isolated from the root bark of Melicope semecarpifolia. The structures of 1-3 were elucidated by means of spectral analysis. In addition, (2S)-(--)-7,8-dimethoxyplatydesmine (4), cis-(+)-7,8-dimethoxymyrtopsine (5), and (3R)-(--)-8,9-dimethoxygeibalansine (6) were isolated as new natural products. Several of these isolates were determined as exhibiting significant antiplatelet aggregation activities in vitro.

Alkaloids↗
PubMed2001

A new tetrahydroprotoberberine N-oxide alkaloid and anti-platelet aggregation constituents of Corydalis tashiroi.

A new tetrahydroprotoberberine N-oxide alkaloid, (-)-cis-isocorypalmine N-oxide (1), together with two known compounds, 6-methoxydihydrosanguinarine (2) and norjuziphine (3), were isolated in continuing studies of the entire Formosan Corydalis tashiroi plant. The structures of these three compounds were determined through spectral analyses. In addition, compounds 1, 2, 3 and the seven alkaloids previously reported: (-)-cis-corydalmine N-oxide, (-)-trans-corydalmine N-oxide, (-)-trans-isocorypalmine N-oxide, scoulerine, protopine, oxysanguinarine and corydalmine, were found to possess antiplatelet aggregation activity.

Alkaloids↗
PubMed2001

Vasorelaxing and antioxidant constituents from Hernandia nymphaeifolia.

Three new alkaloids, (+)-nymphaedaline (1), oxo-O-methylbulbocapnine (2), and (+)-laetine (3), have been isolated from the trunk bark of Hernandia nymphaeifolia. The structures of these new compounds were elucidated by spectroscopic analysis. Among the isolates of this plant obtained till now, sixteen compounds show effective inhibitory activities on the contraction of vascular smooth muscles induced by high K+ (80 mM) or norepinephrine (3 microM). In addition, eight compounds showed effective antioxidant activities in scavenging the stable free radical, diphenyl-picryl-hydrazyl (DPPH).

Alkaloids↗
PubMed2001

Bacterial artificial chromosome-based physical map of the rice genome constructed by restriction fingerprint analysis.

Genome-wide physical mapping with bacteria-based large-insert clones (e.g., BACs, PACs, and PBCs) promises to revolutionize genomics of large, complex genomes. To accelerate rice and other grass species genome research, we developed a genome-wide BAC-based map of the rice genome. The map consists of 298 BAC contigs and covers 419 Mb of the 430-Mb rice genome. Subsequent analysis indicated that the contigs constituting the map are accurate and reliable. Particularly important to proficiency were (1) a high-resolution, high-throughput DNA sequencing gel-based electrophoretic method for BAC fingerprinting, (2) the use of several complementary large-insert BAC libraries, and (3) computer-aided contig assembly. It has been demonstrated that the fingerprinting method is not significantly influenced by repeated sequences, genome size, and genome complexity. Use of several complementary libraries developed with different restriction enzymes minimized the "gaps" in the physical map. In contrast to previous estimates, a clonal coverage of 6.0-8.0 genome equivalents seems to be sufficient for development of a genome-wide physical map of approximately 95% genome coverage. This study indicates that genome-wide BAC-based physical maps can be developed quickly and economically for a variety of plant and animal species by restriction fingerprint analysis via DNA sequencing gel-based electrophoresis.

Chromosomes, Artificial, Bacterial↗
PubMed2001

An integrated map of Arabidopsis thaliana for functional analysis of its genome sequence.

The genome of the model plant species Arabidopsis thaliana has recently been sequenced. To accelerate its current genome research, we developed a whole-genome, BAC/BIBAC-based, integrated physical, genetic, and sequence map of the A. thaliana ecotype Columbia. This new map was constructed from the clones of a new plant-transformation-competent BIBAC library and is integrated with the existing sequence map. The clones were restriction fingerprinted by DNA sequencing gel-based electrophoresis, assembled into contigs, and anchored to an existing genetic map. The map consists of 194 BAC/BIBAC contigs, spanning 126 Mb of the 130-Mb Arabidopsis genome. A total of 120 contigs, spanning 114 Mb, were anchored to the chromosomes of Arabidopsis. Accuracy of the integrated map was verified using the existing physical and sequence maps and numerous DNA markers. Integration of the new map with the sequence map has enabled gap closure of the sequence map and will facilitate functional analysis of the genome sequence. The method used here has been demonstrated to be sufficient for whole-genome physical mapping from large-insert random bacterial clones and thus is applicable to rapid development of whole-genome physical maps for other species.

Arabidopsis↗
PubMed2001

Multicentricity of intraparotid facial nerve schwannomas.

Facial nerve schwannomas are uncommon neoplasms. Multiple schwannomas of the facial nerve in the parotid region are rare. Research regarding the pathogenesis of multiple facial nerve schwannomas is incomplete. Both the neoplastic bridging of tumor cells and tumor multicentricity have been hypothesized. We present a case of multiple intraparotid facial nerve schwannomas. In this case, the histologic features of the tumors support the multicentric hypothesis.

Adult↗
PubMed2001

Synthesis, antiplatelet and vasorelaxing effects of monooxygenated flavones and flavonoxypropanolamines.

A series of flavones and flavonoxypropanolamines were synthesized and tested in-vitro for their ability to inhibit aggregation of washed rabbit platelets and human platelet-rich plasma (PRP), and for vasoconstriction of rat thoracic aorta. The various substituted positions of the hydroxyl group in flavone ring B and the various oxypropanolamine side chains substituted at position C-2' of flavone modified the antiplatelet effects. All the compounds tested in human PRP showed significant inhibition of secondary aggregation induced by adrenaline (epinephrine), suggesting that the antiplatelet effect of these compounds is mainly due to an inhibitory effect on thromboxane formation. Compounds 11 and 12 also had potent vasorelaxant effects in rat thoracic aorta. Phenylephrine- and high-K+-induced 45Ca2+ influx in aorta were both inhibited by the selected compound 11. This result indicates that the inhibitory effect of 11 on the contractile response caused by high-K+ medium and noradrenaline (norepinephrine) in rat thoracic aorta is mainly due to inhibition of Ca2+ influx through both voltage-dependent and receptor-operated Ca2+ channels.

Animals↗
PubMed2001

Primary cutaneous adenoid cystic carcinoma with regional lymph node metastasis.

Primary cutaneous adenoid cystic carcinoma (PCACC) is a particularly rare variant of sweat gland carcinoma with characteristics of indolent and progressive course and high incidence of perineural invasion and local recurrence. However, regional lymph node metastasis in PCACC is exceedingly rare and its prognostic implication is unknown. Only two previous cases of recurrent scalp PCACC were reported to be associated with cervical lymph node metastases at 42 months and 20 years, respectively, after the initial treatment. We present a case of PCACC occurring in the left parotid region with regional neck lymph node metastasis in a 64-year-old man. Because the occurrence of lymph node metastasis seems to be associated with recurrent PCACC, we suggest that neck dissection may be included in the treatment for recurrent PCACC patients.

Carcinoma, Adenoid Cystic↗
PubMed2001

Video-assisted thoracoscopic surgery for the diagnosis of patients with hilar and mediastinal lymphadenopathy.

In areas where tuberculosis (TB) is rare, cases of hilar and mediastinal lymphadenopathy are often attributed to the diagnosis of sarcoidosis or a malignant process. However, these manifestations have been only sparsely reported in countries with high rates of TB. The role of simultaneous lung biopsy in the differential diagnosis of these patients using a thoracoscopic approach is also undetermined. In this prospective study, 15 adult patients with hilar and mediastinal lymphadenopathy were evaluated using video-assisted thoracoscopy during the period from May 1995 through September 1999. Biopsy of the hilar and mediastinal lymph nodes was undertaken in all 15 patients, and a wedge biopsy of the lungs was performed whenever frozen section of the nodes disclosed granulomatous inflammation. The final diagnoses included sarcoidosis (10 patients), TB (2), metastatic small cell carcinoma (2), and reactive lymphoid hyperplasia (1). No morbidity or mortality was associated with the operation. In patients with sarcoidosis and TB, most of the lymph node biopsy specimens disclosed extensive hyaline fibrosis. Lung biopsy specimens presented small non-necrotizing granulomas with multinucleated giant cells even in the absence of demonstrable parenchymal lesions. In the two patients with TB, identification of acid-fast bacilli and growth of Mycobacterium tuberculosis occurred only in lung specimens and not in specimens from lymph nodes. Video-assisted thoracoscopic surgery is a safe, simple, and effective procedure for the diagnosis of patients with hilar and mediastinal lymphadenopathy. Our results suggest that for a better differentiation between TB and sarcoidosis, an additional lung biopsy could be undertaken to provide specimens for microscopic examination and culture.

Adult↗
PubMed2001

Chinese herbal remedy wogonin inhibits monocyte chemotactic protein-1 gene expression in human endothelial cells.

Wogonin (Wog), an active component of Scutellaria baicalensis, has antioxidant and anti-inflammatory properties. Monocyte chemotactic protein-1 (MCP-1), a potent chemoattractant for monocytes, plays a crucial role in case of early inflammatory responses, including atherosclerosis. In this study, we investigated the effect of Wog on phorbol ester (PMA)-induced MCP-1 expression in human umbilical vein endothelial cells (ECs). The MCP-1 mRNA levels and MCP-1 release in Wog-treated ECs were measured. Wog inhibited PMA-induced MCP-1 mRNA levels and MCP-1 secretion in a dose-dependent manner. The inhibition of MCP-1 induction by Wog is a transcriptional event, as shown by Wog's significant reduction of both MCP-1 promoter and 4x 12-O-tetradecanoylphorbol-13-acetate response element-luciferase reporter activities. By electrophoretic mobility assay, Wog significantly reduced the AP-1 binding activity induced by PMA. Furthermore, the PMA-induced extracellular signal-regulated kinase 1/2 and c-Jun amino-terminal kinase activities that contributed to AP-1 activity and MCP-1 gene induction were obviously attenuated after pretreating ECs with Wog. The decrease of MCP-1 secretion by Wog pretreatment led to a reduction of monocyte adhesion to ECs. Taken together, our results demonstrate that Wog inhibits MCP-1 induction in ECs; this inhibition is mediated by reducing AP-1 transcriptional activity via the attenuation of ERK1/2 and JNK signal transduction pathways. We conclude that Wog has the potential therapeutic development for use in anti-inflammatory and vascular disorders.

Antioxidants↗
PubMed2001

Methimazole-induced pulmonary hemorrhage associated with antimyeloperoxidase-antineutrophil cytoplasmic antibody: a case report.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis has been recently recognized in Graves' disease patients treated with antithyroid drugs. We describe the case of an 18-year-old girl who developed antimyeloperoxidase ANCA (MPO-ANCA)-positive vasculitis manifesting as a skin lesion and hemoptysis with hypoxic respiratory failure after taking methimazole. An open lung biopsy was consistent with acute capillaritis. Both skin and sural nerve biopsy showed lymphocytic vasculitis. Administration of steroid and plasmapheresis produced a good clinical response.

Adolescent↗
PubMed2000

Determination of unbound cephalothin in rat blood by on-line microdialysis and microbore liquid chromatography.

A method of analysis for the determination of unbound cephalothin in rat blood has been developed. The method was fully automated using an on-line microdialysis procedure. A microdialysis probe was inserted into the jugular vein/right atrium of male Sprague-Dawley rats to examine the unbound cephalothin level in the rat blood after cephalothin administration (50 mg/kg, i.v.). Dialysates were directly input to a liquid chromatographic system using an on-line injector. Samples were eluted with a mobile phase containing methanol-acetonitrile-100 mM monosodium phosphate (pH 5.0) (20:20:60, v/v). The UV wavelength was set at 254 nm for monitoring the analyte. Using the retrograde method, at infusion concentrations of 1 and 5 microg/ml of cephalothin, the in vivo microdialysis recoveries were 48.4+/-4.5% and 52.9+/-4.7% for the rat blood (n=6). Intra- and inter-assay accuracy and precision of the analyses were < or = 10% in the range of 0.01 through 10 microg/ml. Pharmacokinetic parameters were calculated from the recovery corrected dialysate concentrations of cephalothin versus time data. The results suggest that the pharmacokinetics of unbound cephalothin in blood fitted best to the two-compartmental model following cephalothin administration (50 mg/kg, i.v.).

Animals↗
PubMed2000

Simultaneous blood and brain sampling of cephalexin in the rat by microdialysis and microbore liquid chromatography: application to pharmacokinetics studies.

To circumvent the need for laborious sample clean-up and multiple blood sampling, a system was developed consisting of on-line microdialysis coupled to microbore liquid chromatography and ultraviolet detection. The system was designed for the simultaneous and continuous monitoring of unbound blood and brain cephalexin in the rat following single bolus intravenous administrations (10 mg/kg, n = 6). Microdialysis probes were inserted into the jugular vein and brain striatum, respectively, for blood and brain sampling. Chromatographic conditions consisted of a mobile phase of methanol-100 mM monosodium phosphoric acid (20:80, v/v, pH 5.0) pumped through a microbore reversed-phase column at a flow-rate of 0.05 ml/min. Detection wavelength was set at 260 nm. The method was validated for response linearity as well as intra- and inter-day variabilities. Rapid appearance of cephalexin in the striatal dialysate suggested good blood-brain barrier penetration. This study provided pharmacokinetics information for cephalexin as well as demonstrated the applicability of this continuous sampling method for pharmacokinetics studies.

Animals↗
PubMed2000

Calcium and phosphate supplementation promotes bone cell mineralization: implications for hydroxyapatite (HA)-enhanced bone formation.

Organic phosphate, in particular beta-glycerophosphate (beta-GP), has been used to induce mineralization in cell culture systems. It serves as a source of inorganic phosphate when hydrolyzed by alkaline phosphatase. This study examined the effect of supplemental calcium and phosphate as well as the influence of various metabolic inhibitors on mineralization in a rat osteoblast-like cell-culture system. Mineralization was induced by supplementation of 1.8 mM of Ca(+2) and 5 mM of beta-GP or Pi. Mineral deposits associated with in vitro mineralization were revealed under SEM and TEM. Levamisole (10-100 microM) inhibited alkaline phosphatase activity and effectively reduced mineral formation. Actinomycin (500 ng/mL) and cycloheximide (50 microg/mL) also reduced mineral depositions by blocking RNA synthesis and protein synthesis, respectively. Levamisole and beta-GP did not appear to influence DNA synthesis. Spontaneous precipitation of calcium phosphate mineral was not detected in the culture medium with calcium and phosphate supplements in the absence of cell culture. The findings suggest that an elevated concentration of calcium and phosphate is crucial for in vitro mineralization. Furthermore, the mineralization process is associated with biologic events rather than with a spontaneous precipitation of calcium phosphate mineral. In view of the degradation potential of hydroxyapatite (HA)-coated implants, these results may be a viable indication that HA enhances bone formation through a similar mechanism.

Animals↗
PubMed2000

E-cadherin expression in surgically-resected non-small cell lung cancers--a clinicopathological study.

BACKGROUND: E-Cadherin is a subclass of the cadherin family that plays a major role in the maintenance of intercellular junctions in normal epithelium. Decreased expression of E-cadherin might be closely related to invasiveness and dedifferentiation in human cancers. This study is aimed at investigating the clinicopathological significance of E-cadherin expression and its impact on the prognosis in surgically resected non-small-cell lung cancer patients. METHODS: Using immunohistochemical staining, the expression of E-cadherin was studied in 207 surgically resected lung cancer specimens from January 1990 through December 1994. The clinicopathological data and survival status were recorded and analysed against the E-cadherin expression level in each tumor. RESULTS: E-cadherin expression was detected in 122 of the 207 lung tumors (59.0%), and the expression was significantly lower in tumors with poor differentiation (p < 0.001), in tumors with vascular invasion (p < 0.05), and in tumors with direct invasion into surrounding structures (p < 0.01). There was no correlation between E-cadherin expression, and tumor stage and regional lymph-node metastasis. There was no significant difference in survival rate between higher (> 40%) and lower (< 40%) E-cadherin expression groups; however, in tumors 3 cm or less, a significant difference was found between higher and lower E-cadherin expressions (p < 0.0001). CONCLUSIONS: Underexpression of E-cadherin is associated with poor differentiation and invasiveness in NSCLC. In patients with small NSCLC (< or = 3 cm), higher E-cadherin expression (> 40%) significantly had a favorable prognosis.

Adult↗
PubMed2000

Anti-platelet aggregation alkaloids and lignans from Hernandia nymphaeifolia.

A new aporphine, N-(N-methylcarbamoyl)-O-methyl-bulbocapnine (1), together with seven known compounds, (-)-5'-methoxypodorhizol (2), a mixture of beta-sitosterone (3) and stigmasta-4,22-dien-3-one (4), a mixture of 3 beta-hydroxystigmast-5-en-7-one (5) and 3 beta-hydroxystigmasta-5,22-dien-7-one (6), and a mixture of 6 alpha-hydroxystigmast-4-en-3-one (7) and 6 alpha-hydroxystigmasta-4,22-dien-3-one (8), were isolated in continuing studies on the trunk bark of Formosan Hernandia nymphaeifolia. The structures of these compounds were determined through spectral analyses. In addition, the previously reported six alkaloids, laurotetanine, oxohernagine, thalicarpine, reticuline, (+)-vateamine-2'-beta-N-oxide, (+)-hernandaline and six lignans, (+)-epiaschantin, (+)-epimagnolin, (+)-epiyangambin, (-)-hernone, (-)-yatein, (-)-deoxypodophyllotoxin were demonstrated to have anti-platelet aggregation activity.

Alkaloids↗