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C C Lin

Publications and source records attributed to C C Lin.

At least 145 records · Page 8Linked to original sources
PubMed1999

ER/Golgi intermediates acquire Golgi enzymes by brefeldin A-sensitive retrograde transport in vitro.

Secretory proteins exit the ER in transport vesicles that fuse to form vesicular tubular clusters (VTCs) which move along microtubule tracks to the Golgi apparatus. Using the well-characterized in vitro approach to study the properties of Golgi membranes, we determined whether the Golgi enzyme NAGT I is transported to ER/Golgi intermediates. Secretory cargo was arrested at distinct steps of the secretory pathway of a glycosylation mutant cell line, and in vitro complementation of the glycosylation defect was determined. Complementation yield increased after ER exit of secretory cargo and was optimal when transport was blocked at an ER/Golgi intermediate step. The rapid drop of the complementation yield as secretory cargo progresses into the stack suggests that Golgi enzymes are preferentially targeted to ER/Golgi intermediates and not to membranes of the Golgi stack. Two mechanisms for in vitro complementation could be distinguished due to their different sensitivities to brefeldin A (BFA). Transport occurred either by direct fusion of preexisting transport intermediates with ER/Golgi intermediates, or it occurred as a BFA-sensitive and most likely COP I-mediated step. Direct fusion of ER/Golgi intermediates with cisternal membranes of the Golgi stack was not observed under these conditions.

Animals↗
PubMed1999

High-performance liquid chromatographic analysis of the D4 receptor antagonist SCH 66712 in rat plasma.

SCH 66712 is a potent and selective dopamine D4 receptor antagonist. An HPLC method was developed for the analysis of SCH 66712 in the plasma of rats, a species used for safety evaluation of this compound. The method involved solid-phase extraction on an ethyl cartridge and HPLC separation on a reversed-phase C8 column with quantitation using a fluorescence detector. The calibration curve was linear over a concentration range of 5-100 ng/ml. The limit of quantitation was 5 ng/ml, where the coefficient of variation (C.V.) was 2.9% and the bias was 6%. The precision of the method was satisfactory as indicated by an intra-day C.V. of < or = 4% and an inter-day C.V. of < or = 6%. The accuracy was also satisfactory as shown by an intra-day bias of < or = 8% and an inter-day bias of < or = 9%. The assay was shown to be sensitive, specific, accurate, precise, and reliable for use in pharmacokinetic or toxicokinetic studies.

Animals↗
PubMed1999

GTP hydrolysis by arf-1 mediates sorting and concentration of Golgi resident enzymes into functional COP I vesicles.

Upon addition of GTPgammaS to in vitro budding reactions, COP I vesicles form but retain their coat, making them easy to isolate and analyze. We have developed an in vitro budding assay that reconstitutes the formation of COP I-derived vesicles under conditions where GTP hydrolysis can occur. Once formed, vesicles are uncoated and appear functional as they fuse readily with acceptor membranes. Electron microscopy shows a homogeneous population of uncoated vesicles that contain the medial/trans Golgi enzyme alpha1, 2-mannosidase II. Biochemical quantitation of vesicles reveals that resident Golgi enzymes are up to 10-fold more concentrated than in donor membranes, but vesicles formed in the presence of GTPgammaS show an average density of resident Golgi enzymes similar to that seen in donor membranes. We show that the sorting process is mediated by the small GTPase arf-1 as addition of a dominant, hydrolysis-deficient arf-1 (Q)71(L) mutant produced results similar to that of GTPgammaS. Strikingly, the average density of the anterograde cargo protein, polymeric IgA receptor, in COP I-derived vesicles was similar to that found in starting membranes and was independent of GTP hydrolysis. We conclude that hydrolysis of GTP bound to arf-1 promotes selective segregation and concentration of Golgi resident enzymes into COP I vesicles.

ADP-Ribosylation Factor 1↗
PubMed1999

Terminal deletion of chromosome 10q at band 26.1: follow-up in an adolescent male with high-output renal failure from congenital obstructive uropathy.

We report on the clinical findings in an adolescent male with a de novo terminal deletion of chromosome 10 del(10)(q26.1). This young man is one of the oldest known patients reported with this condition. His condition is compared with that of 11 reported cases of de novo terminal deletion of 10q at band 26. Individuals with chromosome 10q26 deletion have some findings and medical complications in common. Our patient has chronic renal failure due to urinary tract obstruction from posterior urethral valves. Similar anomalies have been reported in cases of 10q26 deletion, suggesting a careful renal/urinary tract evaluation should be completed in individuals with this condition.

Adolescent↗
PubMed1999

Simple and sensitive high-performance liquid chromatographic method for the determination of an everninomycin, SCH 27899, in rat plasma.

A simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of SCH 27899, an everninomycin antibiotic, in rat plasma. The method involved plasma protein precipitation with acetonitrile, followed by reversed-phase HPLC analysis using a polymeric column and a mobile phase containing acetonitrile and ammonium phosphate, pH 7.8. The linear relationship between detector response and concentration was demonstrated with a correlation coefficient of larger than 0.996 at concentrations ranging from 0.2 to 100 microg/ml. The results showed that the HPLC method was accurate (bias < or = 6%) and precise (coefficient of variation, C.V. < or = 6%). The limit of quantitation was 0.2 microg/ml with a C.V. of 2.6% and bias of 5%. SCH 27899 was stable in rat plasma at -20 degrees C for at least 40 days. The HPLC method has been utilized for the determination of SCH 27899 in plasma samples from rats following single intravenous administration (3 mg/kg).

Aminoglycosides↗
PubMed1999

High-performance liquid chromatographic analysis of the anti-tumor agent SCH 66336 in cynomolgus monkey plasma and evaluation of its chiral inversion in animals.

SCH 66336 is a novel non-cytotoxic anti-tumor agent that is in phase I/II clinical trials for the treatment of solid tumors. This compound is a single enantiomer with one chiral center. Prior to evaluation of this drug candidate in man, it was necessary to evaluate its pharmacokinetics and possible chiral inversion in animals. Thus, high-performance liquid chromatographic (HPLC) methods have been developed for its determination in cynomolgus monkey plasma and for the evaluation of its chiral inversion in rats and cynomolgus monkeys. The achiral HPLC analysis involved extraction with 30% methylene chloride in hexane followed by separation on a CN column and quantitation by UV absorbance at 280 nm. The method was linear over a concentration range of 0.1 to 20 microg/ml in monkey plasma. The chiral HPLC analysis involved the use of a Chiralpak AD column set at 39 degrees C with a mobile phase of hexane-ethanol-diethylamine mixture and a UV detector set at 280 nm. Plasma samples were subjected to solid-phase extraction on a C2 cartridge prior to HPLC analysis. The method was linear over a concentration range of 0.25 to 10 microg/ml in rat and cynomolgus monkey plasma for both enantiomers. Both methods showed good linearity (r2>0.99), accuracy (bias< 13%) and precision (CV<12%). Chiral HPLC analysis indicated that SCH 66336 was not subjected to chiral inversion in rats and cynomolgus monkeys.

Animals↗
PubMed1999

Development of an automated mass spectrometry system for the quantitative analysis of liver microsomal incubation samples: a tool for rapid screening of new compounds for metabolic stability.

There is a continuing need for increased throughput in the evaluation of new drug entities in terms of their pharmacokinetic parameters. One useful parameter that can be measured in vitro using liver microsomal preparations is metabolic stability. In this report, we describe an automated system that can be used for unattended quantitative analysis of liver microsomal samples for a series of compounds. This system is based on the Sciex API 150 (single quadrupole) liquid chromatography/mass spectrometry system and utilizes 96-well plate autosampler technology as well as a custom-designed AppleScript which executes the on-line data processing and report generation. It has the capability of analyzing at least 75 compounds per week or 300 compounds per month in an automated fashion.

Autoanalysis↗
PubMed1999

Demonstration of the capabilities of a parallel high performance liquid chromatography tandem mass spectrometry system for use in the analysis of drug discovery plasma samples.

There is a continuing need for increased throughput in the evaluation of new drug entities in terms of their pharmacokinetic (PK) parameters. This report describes an alternative procedure for increasing the throughput of plasma samples assayed in one overnight analysis: the use of parallel high performance liquid chromatography (HPLC) combined with tandem mass spectrometry (parallel LC/MS/MS). For this work, two HPLC systems were linked so that their combined effluent flowed into one tandem MS system. The parallel HPLC/APCI-MS/MS system consisted of two Waters 2690 Alliance systems (each one included an HPLC pump and an autosampler) and one Finnigan TSQ 7000 triple quadrupole mass spectrometer. Therefore, the simultaneous chromatographic separation of the plasma samples was carried out in parallel on two HPLC systems. The MS data system was able to deconvolute the data to calculate the results for the samples. Using this system, 20 compounds were tested in one overnight assay using the rapid rat PK screening model which includes a total of 10 standards plus samples and two solvent blanks per compound tested. This application provides an additional means of increasing throughput in the drug discovery PK assay arena; using this approach a two-fold increase in throughput can be achieved in the assay part of the drug discovery rat PK screening step.

Animals↗
PubMed1999

Application of FTA sample collection and DNA purification system on the determination of CTG trinucleotide repeat size by PCR-based Southern blotting.

Myotonic dystrophy (DM) is caused by a CTG trinucleotide expansion mutation at exon 15 of the myotonic dystrophy protein kinase gene. The clinical severity of this disease correlates with the length of the CTG trinucleotide repeats. Determination of the CTG repeat length has been primarily relied on by Southern blot analysis of restriction enzyme-digested genomic DNA. The development of PCR-based Southern blotting methodology provides a much more sensitive and simpler protocol for DM diagnosis. However, the quality of the template and the high (G+C) ratio of the amplified region hamper the use of PCR on the diagnosis of DM. A modified PCR protocol to amplify different lengths of CTG repeat region using various concentrations of 7deaza-dGTP has been reported (1). Here we describe a procedure including sample collection, DNA purification, and PCR analysis of CTG repeat length without using 7-deaza-dGTP. This protocol is very sensitive and convenient because only a small number of nucleate cells are needed for detection of CTG expansion. Therefore, it could be very useful in clinical and prenatal diagnosis as well as in prevalence study of DM.

Blood Specimen Collection↗
PubMed1999

Effects of SCH 59228, an orally bioavailable farnesyl protein transferase inhibitor, on the growth of oncogene-transformed fibroblasts and a human colon carcinoma xenograft in nude mice.

The products of the Ha-, Ki-, and N-ras proto-oncogenes comprise a family of 21 kDa guanine nucleotide-binding proteins which play a crucial role in growth factor signal transduction and in the control of cellular proliferation and differentiation. Activating mutations in the ras oncogenes occur in a wide variety of human tumors. Ras proteins undergo a series of posttranslational processing events. The first modification is addition of the 15-carbon isoprene, farnesyl, to a Cys residue near the carboxy-terminus of Ras. Prenylation allows the Ras oncoprotein to localize to the plasma membrane where it can initiate downstream signalling events leading to cellular transformation. Inhibitors of the enzyme which catalyzes this step, farnesyl protein transferase (FPT), are a potential class of novel anticancer drugs which interfere with Ras function. SCH 59228 is a tricyclic FPT inhibitor which inhibits the farnesylation of purified Ha-Ras with an IC50 of 95 nM and blocks the processing of Ha-Ras in Cos cells with an IC50 of 0.6 microM. SCH 59228 has favorable pharmacokinetic properties upon oral dosing in nude mice. The in vivo efficacy of SCH 59228 was evaluated using a panel of tumor models grown in nude mice. These included several rodent fibroblast lines expressing mutationally-activated (val12) forms of the Ha-Ras oncogene. In some cases, these proteins contain their native C-terminal sequence (CVLS) which directs farnesylation. In one model, the C-terminal sequence was altered to CVLL, making the expressed protein a substrate for a distinct prenyl transferase, geranylgeranyl protein transferase-1. When dosed orally at 10 and 50 mg/kg (four times a day, 7 days a week) SCH 59228 significantly inhibited tumor growth of cells expressing farnesylated Ha-Ras in a dose-dependent manner; over 90% growth inhibition was observed at the 50 mg/kg dose. Tumor growth of cells expressing the geranylgeranylated form of Ha-Ras was less potently inhibited. Growth of tumors derived from a rodent fibroblast line expressing activated Ki-Ras containing its native C-terminal sequence (CVIM), which preferentially directs farnesylation, was also inhibited by SCH 59228. Inhibition in the Ki-Ras model was less than that observed in the Ha-Ras model. In contrast, tumors derived from cells transformed with the mos oncogene were not significantly inhibited even at the highest dose level. SCH 59228 also significantly and dose-dependently inhibited the growth of human colon adenocarcinoma DLD-1 xenografts (which express activated Ki-ras). These results indicate that SCH 59228 possesses in vivo antitumor activity upon oral dosing in tumor models expressing activated ras oncogenes. This is the first report of oral antitumor activity with an FPT inhibitor. These results are discussed in light of recent observations on alternative prenylation of some Ras isoforms.

Alkyl and Aryl Transferases↗
PubMed1999

Placental glutathione S-transferase isoenzyme expression during promotion of two-stage hamster cheek-pouch carcinogenesis.

Glutathione S-transferases (GSTs) are the products of a multigene family. A well-established function of GSTs is to metabolize carcinogens by catalysing the conjugation of electrophilic substrates to glutathione. Whether placental GST (GST-P) is expressed during the promotion of two-stage hamster buccal-pouch mucosa (HBPM) carcinogenesis was investigated here, using 7,12-dimethylbenz[a]anthracene (DMBA) as the initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as the promoter. Cytoplasmic and nuclear staining for GST-P was seen in pouches treated with DMBA for 4 or 16 weeks, as well as in those treated with DMBA for 4 weeks and then TPA for 12 weeks. No GST-P positivity was seen in any pouches treated with only TPA or with mineral oil for either 4 or 16 weeks. The average number of GST-P-stained foci in the groups treated with DMBA for 16 weeks (246 +/- 96; mean +/- SD) or DMBA for 4 weeks followed by TPA for 12 weeks (186 +/- 67) was significantly higher than in pouches treated with only DMBA for 4 weeks (97 +/- 24). These results demonstrate that TPA alone is not sufficient for GST-P expression in hamster buccal pouch mucosa. However, after being initiated with DMBA, then promoted with TPA, GST-P activity is induced in hamster buccal pouch mucosa during squamous-cell carcinogenesis. This underpins the suggestion that GST-P may play an important part during the promotion stage of oral carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Current concepts of fetal growth restriction: part II. Diagnosis and management.

OBJECTIVE: To update diagnostic concepts and management strategies of fetal growth restriction (FGR). DATA SOURCE: An English literature search was conducted for pertinent articles related to FGR from 1976 to 1997 including original research articles, review articles, and book chapters. METHODS OF STUDY SELECTION: In part II, clinical studies involving both diagnostic and therapeutic approaches to the management of FGR were included. Throughout the study period, the evolution of concepts is demonstrated. TABULATION, INTEGRATION, AND RESULTS: Diagnostic methods including two- and three-dimensional ultrasound for diagnosis of fetal structural abnormalities, organ volumetry, and estimating fetal weight are presented. Clinical tools to assess fetal well-being such as nonstress tests, contraction stress tests, biophysical profile scores, and Doppler blood flow velocimetry of fetal circulation and funicentesis are discussed. Correlations between these indirect fetal evaluations and fetal blood biochemical parameters obtained by funicentesis are also reviewed. Finally, various therapeutic approaches, especially timing of delivery of growth-restricted fetuses, are formulated. CONCLUSION: We suggest that both diagnostic and therapeutic approaches to FGR should be modified. With the current development of technology, newly available three-dimensional ultrasound might offer more precise diagnostic data than conventional two-dimensional ultrasonography in the near future. From current concepts of pathophysiology of FGR, morphometric measurement abnormality alone should not be a basis for intervention. Combined use of morphometric measurements and functional evaluation tests and good clinical judgment using flexibility and individualization are the key elements in successful management of FGR.

Fetal Growth Retardation↗
PubMed1999

Anti-inflammatory effects of Taiwan folk medicine 'Teng-Khia-U' on carrageenan- and adjuvant-induced paw edema in rats.

'Teng-Khia-U' is a folk medicine from Taiwan, derived from the entire plants of Elephantopus scaber L., E. mollis H.B.K. and Pseudoelephantopus spicatus (Juss.) Rohr (Compositae). To evaluate the anti-inflammatory activities of these crude drugs, models with carrageenan-induced acute arthritis and complete Freund's adjuvant (CFA)-induced chronic arthritis in rats were conducted. The results indicated that pretreatment with 'Teng-Khia-U' significantly inhibited the carrageenan-induced acute arthritis. Moreover, they also significantly suppressed the development of chronic arthritis induced by CFA.

Animals↗
PubMed1999

Difference in the effects of radioprotection between aerial and root parts of Lycium chinense.

Radiation protection from bone marrow death by consecutive injections of crude extracts from different parts of Lycium chinense (LC), root (LCR) and aerial part (LCA), before whole body X-irradiation was confirmed by tests with ICR strain mice. Both extracts were effective after intraperitoneal injection of a high dose, once a day, for seven consecutive days before irradiation. Based on the studies of endogenous hematopoietic spleen colony formation (CFUs), and the postirradiation behavior of hematograms and hematocrits, it was demonstrated that the LCR protects mice more effective when given in a dose of 500 mg/kg. Enhanced CFUs was found in the irradiation range of 4-8 Gy by various treatments. Recovery of leukocyte, erythrocyte and thrombocyte counts was significantly stimulated by the extract of LCR with 500 mg/kg administration. Stimulated recovery by the extract from the LCR was also observed in hematocrit. On the contrary, the extracts of both LCA and LCR did not markedly affect recovery of leukocyte, erythrocyte, thrombocyte counts and hematocrits by 250 mg/kg administration. It could be deduced that the uncertainly radioprotective action is induced by a possible process of enhanced regeneration of the hematopoietic stem cells due to either enhanced postirradiation repair or an increased proliferation of the hematopoietic stem cells under the suitable extract administration.

Animals↗
PubMed1999

Disclosure of the cancer diagnosis as it relates to the quality of pain management among patients with cancer pain in Taiwan.

This study was designed to explore: (1) who is responsible for disclosing to Taiwanese cancer patients the diagnosis of cancer, (2) the extent of disclosure, and (3) the relationship between the disclosure of the cancer diagnosis and the quality of cancer pain management as perceived by the patients experiencing cancer pain. One hundred twelve cancer patients with pain were recruited from three teaching hospitals in Taiwan. The major findings in this study were as follows: the majority of the patients with pain (79%) had been informed that the diagnosis was cancer, and for the majority (89%) the disclosure of cancer had been made by their physicians; older patients and those with lower levels of education were less likely to be told that they had been diagnosed with cancer; and patients to whom it was disclosed that the diagnosis was cancer tended to experience lower levels of pain intensity, lower levels of pain interference, and higher levels of satisfaction with pain management provided by clinicians. These findings provide significant implications for disclosure practice for Taiwanese oncology clinicians.

Adult↗
PubMed1999

Pharmacological and functional characterization of bradykinin receptors in rat cultured vascular smooth muscle cells.

The pharmacological properties of bradykinin receptors were characterized in rat cultured vascular smooth muscle cells (VSMCs) using [3H]-bradykinin as a ligand. Analysis of binding isotherms gave an apparent equilibrium dissociation constant (K(D)) of 1.2 +/- 0.2 nM and a maximum receptor density (Bmax) of 47.3 +/- 4.4 fmol/mg protein. The specific binding of [3H]-bradykinin to VSMCs was inhibited by the B2 receptor-selective agonists (bradykinin and kallidin) and antagonists ([D-Arg0, Hyp3, Thi5, D-Tic7, Oic8]-bradykinin (Hoe 140) and [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin) with an order of potency as kallidin = bradykinin = Hoe 140 > [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin, but not by a B1 receptor-selective agonist (des-Arg9-bradykinin) and antagonist ([Leu8, des-Arg9]-bradykinin). Stimulation of VSMCs by bradykinin produced a concentration-dependent inositol phosphate (IP) accumulation, and initial transient peak of [Ca2+]i with half-maximal responses (pEC50) were 7.53 and 7.69, respectively. B2 receptor-selective antagonists (Hoe 140 and [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin) significantly antagonized the bradykinin-induced responses with pK(B) values of 8.3-8.7 and 7.2-7.9, respectively. Pretreatment of VSMCs with pertussis toxin (100 ng/ml, 24 h) did not alter the bradykinin-induced inositol phosphate accumulation and [Ca2+]i changes in VSMCs. Removal of external Ca2+ led to a significant attenuation of responses induced by bradykinin. Influx of external Ca2+ was required for the bradykinin-induced responses, since Ca2+-channel blockers, nifedipine, verapamil, and Ni2+, partially inhibited the bradykinin-induced IP accumulation and Ca2+ mobilization. These results demonstrate that bradykinin stimulates phosphoinositide hydrolysis and Ca2+ mobilization via a pertussis toxin-insensitive G-protein in rat VSMCs. Bradykinin B2 receptors may be predominantly mediating IP accumulation and subsequently induction of Ca2+ mobilization may function as the transducing mechanism for bradykinin-stimulated contraction of vascular smooth muscle.

Animals↗