Effect of glucose and cytokines on the expression of cell adhesion molecules on mesangial cells.
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Cell Adhesion Molecules↗
Biomedical subjects
J Park
Publications and source records attributed to J Park.
Fate and distribution of [14C]S-(N,N-diethyldithiocarbamoyl)-N-acetyl-L-cysteine, an antimutagenic mixed disulfide from disulfiram, in rats.
S-(N,N-Diethyldithiocarbamoyl)-N-acetyl-L-cysteine (AC-DDTC) is a mixed disulfide from disulfiram and N-acetyl-L-cysteine, which possesses putative anticarcinogenic and antimutagenic properties. The present study describes the absorption, distribution, metabolism and excretion of 14C-labeled AC-DDTC in rats. AC-DDTC was well absorbed after oral administration. Based on the excretion of radioactivity in urine, the minimum absorption was about 73%. The rate of absorption was very rapid, with the peak level of radioactivity in plasma after 15 min of administration. Mean Cmax value for N,N-diethyldithiocarbamate (DDTC) after oral dose of AC-DDTC (20 mg/kg) was 3.8 +/- 0.2 nmol/ml at 15 min and the mean residence time was 47.1 +/- 2.8 min. After oral administration of [14C]AC-DDTC, radioactivity was distributed relatively rapidly. Maximum concentrations were observed in the liver (0.443% dose/g), kidneys (0.496% dose/g), oesophagus (0.313% dose/g) and in the adrenals (0.364% dose/g) at 30 min to 1 h after dosing. Liver was the only organ which contains a considerable amount of radioactivity (0.091% dose/g) 24 h after dosing. Two metabolites of AC-DDTC following oral administration were identified in the plasma and liver by GC and HPLC using extractive alkylation technique, namely DDTC and its methyl ester. Urinary excretion was a major route of elimination of radioactivity derived from [14C]AC-DDTC, in that about 73% of the dose was recovered in urine whereas only 14% was found in feces over 7 days.
Acetylcysteine↗
Stopped lower buffer flow electrofractionation: simple electrofractionation for complex protein mixture.
The standard electrofractionation technique simulated the liquid chromatography to create a continuous elution system. Though this continuous lower buffer flow electrofractionation system served as an excellent model for preparative electrophoresis, the restricted current flow caused by electric resistance arising from the column holder prevented the application to the purification of complex protein mixtures. To overcome the electric current problem, the stopped lower buffer flow electrofractionation (SFE) system is designed to work without using a column holder and use prestained markers as the detection tool of protein position during the electrofractionation process. Through this improvement, the SFE system widens the availability of electrofractionation to the purification of complex and low-concentration protein mixtures. In this report, the efficiency of this technique is shown through the partial purification of a 32P-labeled protein in the rat liver microsome.
Animals↗
Beta 3-adrenoceptor agonist-induced down-regulation of Gs alpha and functional desensitization in a Chinese hamster ovary cell line expressing a beta 3-adrenoceptor refractory to down-regulation.
Chinese hamster ovary (CHO) cells transfected to express human beta 2- or beta 3-adrenoceptors (beta 2-CHO and beta 3-CHO cells) were exposed to the beta-adrenoceptor agonist isoprenaline at various concentrations and for differing times. Sustained exposure of the beta 2-CHO but not beta 3-CHO cells to isoprenaline resulted in a time- and concentration-dependent down-regulation of the receptor as measured by a reduction in specific binding of [125I]cyanopindolol. Such maintained exposure of cells expressing either receptor to the agonist produced a marked down-regulation of immunologically detectable levels of the alpha subunit of the stimulatory guanine-nucleotide-binding protein Gs. This effect was specific for Gs because levels of both G12 alpha and Gq alpha/G11 alpha were unaltered by isoprenaline treatment of both beta 2-CHO and beta 3-CHO cells. The effect of isoprenaline on Gs alpha down-regulation was some 30-fold more potent in the beta 2-CHO than in the beta 3-CHO cells. Time courses of isoprenaline-induced down-regulation of Gs alpha were not different, however, in the two cell lines. Isoprenaline treatment of the beta 3-CHO cells produced a desensitization of agonist-mediated regulation of adenylyl cyclase, manifested by a 4-fold reduction in the potency and a 30% reduction in maximal effect of the agonist, whereas desensitization of the beta 2-CHO cells was considerably greater (25-fold reduction in potency and 70% reduction in maximal effect). These results demonstrate that agonist-induced down-regulation of the G-protein which interacts with a receptor can be produced by both beta 2- and beta 3-adrenoceptors. Despite apparent concurrence of down-regulation of receptors and G-proteins in other systems [e.g. Adie, Mullaney, McKenzie and Milligan (1992) Biochem. J. 285, 529-536], agonist-induced receptor down-regulation does not appear to be a prerequisite for down-regulation of the G-protein. Furthermore, the results suggest that agonist-induced down-regulation of a G-protein may be sufficient, in the absence of receptor regulation, to induce some agonist desensitization of effector function.
Amino Acid Sequence↗
Spectroscopic ellipsometry study of Zn1-xCoxSe alloys grown on GaAs.
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Journal Article↗
Magnetic and charge dynamics in a doped one-dimensional transition metal oxide.
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Journal Article↗
Regulation of endocytic trafficking and acidification are independent of the cystic fibrosis transmembrane regulator.
Cystic fibrosis is associated with mutations of the cystic fibrosis transmembrane regulator (CFTR), a cAMP-regulated plasma membrane Cl- channel. Mutations in the CFTR have been reported to not only impair Cl-transport at the plasma membrane but also inhibit organelle acidification and disrupt cAMP-regulated plasma membrane recycling. Comparisons of cultured pancreatic adenocarcinoma cells expressing the delta 508 mutant CFTR (CFPAC-1 cells) with genetically matched CFPAC-1 cells transfected with the wild-type CFTR demonstrate that expression of wild-type CFTR restores cAMP-mediated plasma membrane Cl- transport, but has no effect on pH regulation of endosomes labeled with either transferrin or wheat germ agglutinin. Endosome pH was, in all cases, similar in the two cell lines and unaffected by treatment with the cAMP agonist forskolin. Forskolin treatment had no effect on transferrin internalization, but increased recycling by 30-40% in both cell lines. The kinetics of wheat germ agglutinin recycling were negligibly affected by forskolin in either cell line. These results demonstrate that endocytic acidification and cAMP-mediated endocytic protein redistribution are similar in genetically matched CFPAC-1 cells which differ only in the expression of mutant or wild-type CFTR.
Adenocarcinoma↗
Regulation of amelogenin gene expression during tooth development.
The amelogenins are the predominant matrix proteins in developing enamel and are crucial for proper enamel mineralization. Transgenic mice were constructed in order to identify the segment of the amelogenin gene required for specific expression in enamel organ cells. A 3.5 kb fragment of the bovine X-chromosomal amelogenin gene that includes a TATA box, the transcription initiation site, and 32 bp of exon 1 was linked to the beta galactosidase gene and injected into fertilized mouse eggs. Newborn transgene positive mice expressed beta galactosidase activity in developing teeth treated with the chromogenic substrate Xgal. Foci of ameloblasts were positive in newborn mice; stain intensity and number of positive ameloblasts increased in 1-day and 2-day postnatal mice. Some of the adjacent stratum intermedium cells also were positive in the later stages. Targeting of the transgene to the enamel organ was specific; the only other cells observed to be positive were macrophages, which have endogenous beta galactosidase activity.
Ameloblasts↗
Metabolism and pharmacokinetics of S-(N,N-diethyldithiocarbamoyl)-N-acetyl-L-cysteine in rats.
The metabolism and pharmacokinetics of a mixed disulfide S-(N,N-diethyldithiocarbamoyl)-N-acetyl-L-cysteine (AC-DDTC) were studied in rats. Two metabolites of AC-DDTC following i.v. and p.o. administration were identified in plasma and liver by HPLC and GC, namely N,N-diethyldithiocarbamate (DDTC) and the methyl ester of DDTC (Me-DDTC). AC-DDTC was very unstable in vivo and could not be detected neither in plasma nor in urine. Pharmacokinetic parameters of DDTC following intravenous administration of AC-DDTC (20 mg/kg) were calculated. DDTC has a low affinity to rat tissue and the total body clearance was 9.0 +/- 3.4 ml/min/kg. The mean residence time (MRT) was 111.5 +/- 16.3 min. After oral administration of 20 mg/kg AC-DDTC, maximal plasma concentration (Cmax) was 3.8 +/- 0.2 nmol/ml and the bioavailability was 7.04%. Cmax for DDTC at a dose of 120 mg/kg AC-DDTC was 40.1 +/- 2.2 nmol/ml. MRT was 47.1 +/- 2.8 min at a dose of 20 mg/kg and 110.5 +/- 6.0 min at 120 mg/kg.
Acetylcysteine↗
A new visual enzyme immunoassay of methamphetamine using linear water-soluble polyelectrolytes.
A new visual enzyme immunoassay (EIA) technique has been developed. Oppositely charged synthetic linear water-soluble polyelectrolytes (poly-N-ethyl-4-vinyl-pyridine as polycation and polymethacrylate as polyanion) were used as carriers for reagent immobilization. The ability of these molecules to form an insoluble complex was applied for the separation of bound and free components of the immunoassay reaction mixture. This approach was realized in methamphetamine visual EIA. In the first stage of the assay two specific reactions took place during incubation of the analytical reagents with the probe to be analyzed: (1) competition between methamphetamine and hapten conjugated with peroxidase for the interaction with specific antibodies and (2) interaction of these antibodies with the protein A-polymethacrylate conjugate. As a result of these reactions the (polyanion-protein A)-antibody-(hapten-peroxidase) complex was formed. Then the reaction mixture was filtered through an Ultrabind membrane (0.45 microns) with adsorbed poly-N-ethyl-4-vinylpyridine, and the immunological complexes were immobilized to the membrane by electrostatic interaction. The level of peroxidase binding on the membrane was measured by diaminobenzidine substrate. The system described was optimized to achieve both high rapidity (20 min) and an appropriate sensitivity (0.4 micrograms/ml) for methamphetamine assay.
Animals↗
P-glycoprotein expression in bladder cancer.
Multi-drug resistance is a phenomenon by which tumor cells express resistance to a variety of chemically unrelated chemotherapeutic drugs. The classical form of multi-drug resistance is mediated through the expression of P-glycoprotein, which acts as an energy dependent drug efflux pump. P-glycoprotein expression was evaluated in 29 cystectomy specimens from patients with bladder cancer with no prior exposure to chemotherapeutic drugs, and in bladder biopsies from 9 subjects before treatment with intravesical doxorubicin. Furthermore, the strategy of circumvention of P-glycoprotein-mediated resistance using the combination of doxorubicin and verapamil intravesically was tested in 5 patients. P-glycoprotein was expressed in 75% of the cystectomy specimens. In the doxorubicin treated patients no correlation was noted between P-glycoprotein expression on the initial tumors and subsequent response to doxorubicin. The pilot trial of verapamil and doxorubicin was well tolerated but did not suggest increased efficacy of this combination. P-glycoprotein can be expressed on bladder cancer cells without prior chemotherapy. The role of P-glycoprotein mediated multi-drug resistance in bladder cancer treatment failure remains to be defined.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Retrograde ureteral intussusception.
A soft tissue mass causing ureteral obstruction should be considered malignant until proved otherwise. We report a case of retrograde ureteral intussusception that caused obstruction. To our knowledge, this condition has not been described in the recent literature.
Female↗
Determinants of repetition blindness.
Repetition blindness (RB) for letters presented in rapid serial visual presentation (RSVP) was shown to be highly dependent on absolute stimulus presentation rate (Experiment 1) and on the duration of the 2nd occurrence (C2) but not the 1st occurrence (C1) of the repeated item (Experiment 2). In Experiments 3-6, RB was strongly affected by C1-C2 interstimulus interval but not by response requirements or total memory load. In Experiment 7, sensitivity for detection of the 2nd vowel in an RSVP sequence of consonants was lower when it was identical to the 1st vowel (mean d' = .40) than when it was different (mean d' = .70). It is argued that RB is not due to (a) temporal overlap of C1 and C2 recognition, (b) forgetting of C2, (c) item-specific output interference, (d) response bias, or (e) guessing strategies; rather, RB arises because of the failure to bind recognized types to individuated tokens.
Adult↗
Negative priming for spatial locations: identity mismatching, not distractor inhibition.
Negative priming (NP) is commonly thought to occur because distractor inhibition is necessary for target selection (the distractor inhibition hypothesis). Contrary to this account, the selection of a target in the preceding trial is shown to be neither necessary (Experiment 1) nor sufficient (Experiments 2 and 3) for NP in a target localization task modeled after S.P. Tipper, J.C. Brehaut, and J. Driver (1990). Experiments 4 and 5 provide further evidence against the distractor inhibition hypothesis and support an alternative mismatching account: NP in the spatial selection task apparently results from a change in the symbol bound to a given location (D. Kahneman, A. M. Treisman, & B. J. Gibbs, 1992), rather than a change in the status of that location from distractor to target (S. P. Tipper, J. C. Brehaut, & J. Driver, 1990).
Adult↗
The murine Xe169 gene escapes X-inactivation like its human homologue.
Among a number of genes that escape X-chromosome inactivation in humans, three have been evaluated in mice and unexpectedly all three are subject to X-inactivation. We report here the cloning and expression studies of a novel mouse gene, Xe169, and show that it escapes X-inactivation like its human homologue. Xe169 was assigned to band F2/F3 on the mouse X chromosome by fluorescent in situ hybridization and Southern analysis indicates that the gene is located outside the pseudoautosomal region. Homologous, but divergent, sequences exist on the Y chromosome. In vitro and in vivo studies show that Xe169 is expressed from both the active and the inactive X chromosomes. Xe169 is the first cloned non-pseudoautosomal gene that escapes X-inactivation in mice.
Animals↗
Autosomal dominant hypocalcaemia caused by a Ca(2+)-sensing receptor gene mutation.
Defects in the human Ca(2+)-sensing receptor gene have recently been shown to cause familial hypocalciuric hypercalcaemia and neonatal severe hyperparathyroidism. We now demonstrate that a missense mutation (Glu128Ala) in this gene causes familial hypocalcaemia in affected members of one family. Xenopus oocytes expressing the mutant receptor exhibit a larger increase in inositol 1,4,5-triphosphate in response to Ca2+ than oocytes expressing the wild-type receptor. We conclude that this extracellular domain mutation increases the receptor's activity at low Ca2+ concentrations, causing hypocalcaemia in patients heterozygous for such a mutation.
Amino Acid Sequence↗
A beta-galactosidase expression vector for promoter analysis.
An expression vector plasmid, designated pMCS beta gal, was constructed to contain a multiple cloning site for insertion of gene fragments with potential regulatory function. This plasmid was designed to test promoter activity in transgenic mice, since digestion with Pst I will release all vector sequences, which could inhibit transgene expression in vivo (Jaenisch, 1988). When this vector, containing the amelogenin promoter, was used to make transgenic mice, expression was tissue specific and developmentally regulated similar to the endogenous gene (Chen et al., 1994). In addition, the herpes simplex virus (HSV) thymidine kinase (TK) minimal promoter was inserted into pMCS beta gal to produce pTK beta gal, leaving an Sph I upstream site available for insertion of gene fragments with potential enhancer or silencer function, which can be assayed following transfection into cultured cells.
Animals↗