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Biomedical subjects

Z Lin

Publications and source records attributed to Z Lin.

At least 397 records · Page 22Linked to original sources
PubMed1988

Specificity of the action of cAMP agonists in the induction of RI cAMP-binding protein in mouse neuroblastoma cells.

Differentiation in the mouse neuroblastoma cells is induced by cAMP and is characterized by neurite extension and increased acetylcholinesterase, cAMP-phosphodiesterase, and RI cAMP-binding activities. To gain a better understanding of the regulation of expression and the possible function of the RI cAMP-binding protein in neuroblastoma cell differentiation, we evaluate the specificity of action of cAMP analogues and agents that increased intracellular cAMP concentration in the induction of the 47,000-dalton RI protein. The amount of RI in cell extracts was quantitated by the photoactivated incorporation of 8-N3-[32P]cAMP into the 47,000-dalton RI and by ELISA and Western blot techniques. Our results showed that dibutyryl cAMP, forskolin, prostaglandin E1, 3-isobutyl-1-methyl xanthine, and papavarine gave a 2- to 4-fold increase in the RI cAMP-binding protein coincident with the expression of various morphological and biochemical differentiation phenotypes in the mouse neuroblastoma cells. However, the effects of 8-bromo-cAMP were different. 8-Bromo-cAMP effectively promoted neurite extension and increased acetylcholinesterase and cAMP-phosphodiesterase activities; however, there was no concomitant increase in the RI cAMP-binding protein. The result raises interesting questions concerning the coupling of expression of the various differentiation phenotypes in the mouse neuroblastoma cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1988

Induction and quantitation of the RI cAMP-binding protein in clonal mouse neuroblastoma cell lines: evidence that the increase in RI is not linked to neurite outgrowth.

This is a study of the regulation of expression of the RI cAMP-binding protein in mouse neuroblastoma cells as it relates to neurotransmitter phenotype and neurite outgrowth. Dibutyryl cAMP was used to promote differentiation of the cholinergic NS-20, the adrenergic N1E-115, the neurotransmitter-inactive N-18, and the neurite-minus N1A-103 mouse neuroblastoma cells. The amount of the RI cAMP-binding protein was quantitated by photoaffinity labeling of the 47,000-dalton RI protein with 8-N3-[32P]cAMP and by Western blot, ELISA, and immunocytochemistry. Our results showed that dibutyryl cAMP induced the RI cAMP-binding protein by three to fivefold in each of the four neuroblastoma cell lines examined. The increased expression of the RI cAMP-binding protein was not linked to neurite outgrowth, a parameter of morphological differentiation in the neuroblastoma cells. Thus, the RI cAMP-binding protein can be induced in the neurite-minus N1A-103 neuroblastoma round cells; further, 8-bromo-cAMP effected neurite outgrowth without inducing the RI cAMP-binding protein in the neurite-positive cell lines. Indirect immunocytochemistry of RI showed a cytoplasmic localization with little evidence of nuclear staining. The increase in RI cAMP-binding protein coincided with an increase in the cAMP-phosphodiesterase and a decrease in cAMP-dependent phosphotransferase activity in the mouse neuroblastoma cells.(ABSTRACT TRUNCATED AT 250 WORDS)

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

Neurite extension and increased expression of RI cyclic AMP-binding protein in ouabain-resistant neuroblastoma mutants.

Morphological and biochemical parameters of neuroblastoma differentiation were assessed in 12 clonal derivatives of the N-18 mouse neuroblastoma cell line selected for their ouabain-resistant (ouar) property. When cultured in a normal growth medium, nine of the 12 ouar cell lines exhibited a more complex pattern of neurite outgrowth than the parental N-18 cells. The morphological pattern most frequently observed with the ouar cells was the extension of several branched processes per cell. This pattern of spontaneous neurite outgrowth in the ouar cell lines can be correlated with an increase in expression of the 47,000-dalton RI cyclic AMP (cAMP)-binding protein. The growth rate, intracellular level of cAMP, and acetylcholinesterase activity of the ouar cell lines were not significantly different from those of the parental N-18 neuroblastoma cells. Treatment of the parental and ouar neuroblastoma cell lines with 1 mM N6, O2-dibutyryl cAMP promoted an elaborate pattern of neurite outgrowth and marked increases in acetylcholinesterase and RI cAMP-binding activities. The distinctive pattern of differentiation phenotype exhibited by the ouar cells and the dibutyryl cAMP-induced differentiated neuroblastoma cell suggests that these two protocols yielded different degrees of differentiation. Furthermore, our results suggest a linkage of the biochemical events underlying ouabain resistance and expression of differentiation phenotypes in the mouse neuroblastoma cells.

Animals↗
PubMed1987

Induction of the RI cAMP-binding protein in the "neurite-minus" N1A-103 mouse neuroblastoma cell line.

We examined the effects of agents/conditions that raise intracellular cAMP concentration in the induction of the 47,000-dalton RI cAMP-binding protein in the "neurite-minus" N1A-103 mouse neuroblastoma cells. The amount of RI in cell extracts was quantitated by photoaffinity labeling with 8-N3-[32P]cAMP and by ELISA and Western blot. Our results showed that treatment of the N1A-103 neuroblastoma cells with 20 microM forskolin or 1 mM dibutyryl cAMP, or reducing the serum concentration in the culture medium from 10% to 1% caused a 3-4 fold increase in the amount of RJ. Our results suggest that the induction of RJ can occur independent of morphological differentiation in the mouse neuroblastoma cells.

Affinity Labels↗
PubMed1986

The structure of rabbit muscle phosphoglucomutase at intermediate resolution.

The three-dimensional structure of rabbit phosphoglucomutase has been determined to 2.7 A resolution by a combination of isomorphous and molecular replacement techniques. Heavy atom positions were found by using vector search and difference Fourier methods. The two molecules in the asymmetric unit form a dimer with its 2-fold axis perpendicular to and intersecting with a crystallographic 4(1) axis. Thus, the dimers are arranged so that they form fibers that are coincident with the 4(1) axes. A polypeptide model, corresponding with the known residue sequence, has been fitted to the electron density map to produce a structure that consists of four domains. All four have an alpha/beta structure; the first three have a somewhat similar topology that is based on a mixed parallel/antiparallel beta sheet, whereas the fourth is based on an antiparallel sheet. The active site lies between the four domains, with the phosphoserine residue in the first domain and some of the probable substrate-binding residues in the fourth and final domain. The carboxyl edges of all four sheets are directed towards the active site region, which lies in a deep crevice.

Animals↗
PubMedDate not supplied

Comparison of adaptive filtering in time-, transform- and frequency-domain: an electrogastrographic study.

Adaptive cancellation of motion artifacts in the electrogastrogram (EGG) is presented in this paper. The EGG is a surface measurement of gastric electrical activity. Like other noninvasive electrophysiological measurements, the EGG contains motion artifacts. A number of papers have been published on the adaptive cancellation of motion artifacts or interferences in biomedical signals. Adaptive filtering was performed in time domain in almost all of the previous publications. In this paper, however, three different sorts of adaptive filters were investigated and their efficiencies in cancellation of motion artifacts were compared with each other. These include time-domain, transform-domain, and frequency-domain adaptive filters. A series of simulations were conducted to investigate the performance of these adaptive filters in cancellation of respiratory and motion artifacts. The results show that the frequency-domain adaptive filter has superior performance over the time- and transform-domain adaptive filters in the cancellation of stationary respiratory artifacts in the EGG. Although results focus on the EGG, this paper provides useful information for adaptive filtering of other biomedical signals.

Algorithms↗