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Biomedical subjects

C M Chang

Publications and source records attributed to C M Chang.

At least 145 records · Page 8Linked to original sources
PubMed1985

Characterization of cell surface adenosine 3',5'-monophosphate-binding proteins in Y-1 mouse adrenal tumor cells.

Adrenal cortical cells are known to export cAMP and have binding proteins and cAMP-dependent protein kinase activity associated with their plasma membranes. Because these properties suggest a function for extracellular cAMP, we have undertaken a search for specific cell surface receptors for this cyclic nucleotide. Y-1 mouse adrenal tumor cells actively export cAMP by an energy-dependent process. Analysis of Scatchard plots of the equilibrium binding of [3H]cAMP to these cells indicate the existence of two classes of cAMP binders: one with high affinity (ka = 2.9 X 10(9) M-1) and another with low affinity (ka = 7.0 X 10(7) M-1). The cell surface localization of these binders was established by the sensitivity of both the [3H]cAMP-binding proteins and the [32P]8-N3-cAMP photoaffinity labeled proteins of intact cells to mild trypsin digestion and by the surface distribution of a BSA-O2-monosuccinyl cAMP-gold complex revealed by electron microscopy. Analysis of radioautograms of cell surface cAMP-binding proteins from confluent monolayer tumor cells, photoaffinity labeled with [32P]8-N3-cAMP and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed two major 32P-labeled protein bands which were indistinguishable from the 49,000 and 55,000 mol wt regulatory subunits of the cytosolic protein kinase isoenzymes of this cell. These observations along with the demonstration of cell surface, cAMP-dependent protein kinase activity in the mouse adrenal tumor cell strongly suggest that these cAMP-binding proteins function as regulatory proteins for cell surface protein kinases.

Adrenal Gland Neoplasms↗
PubMed1985

Do pancreatic islets contain significant amounts of phosphoenolpyruvate carboxykinase or ferroactivator activity?

Phosphoenolpyruvate carboxykinase activity was measured in rat pancreatic islet cytosol and mitochondria. No carboxykinase activity was detected under a variety of conditions, including those that increase phosphoenolpyruvate carboxykinase activity in nonislet tissues, such as starving animals or incubating the islet extracts with Fe2+ or Mn2+ before assaying for enzyme activity. The amounts of islet cytosol protein used exceeded those of liver in companion assays used as controls. It was calculated that if islet phosphoenolpyruvate carboxykinase activity was 0.005 that of liver, or 1 X 10(-5) as high as pyruvate kinase activity in islets, it should have been detected in the assays used. Ferroactivator is a protein that permits Fe2+ to activate phosphoenolpyruvate carboxykinase and it is ubiquitous to many tissues that do and even do not contain the carboxykinase. Ferroactivator activity was not detectable in pancreatic islets. Pyruvate kinase, an enzyme that catalyzes a reaction that is essentially the opposite of that catalyzed by phosphoenolpyruvate carboxykinase (i.e., phosphoenolpyruvate formation), is plentiful in islet cytosol. Therefore, even if phosphoenolpyruvate carboxykinase activity is present in pancreatic islets, it is so low that it is unlikely that phosphoenolpyruvate formation would be favored and the contribution of the carboxykinase to intracellular carbohydrate metabolism must be quantitatively unimportant.

Animals↗
PubMed1985

Ultrastructural changes of neuromuscular receptor organs in the masseter muscles following unilateral transection of the rat infraorbital nerve.

Definite ultrastructural changes of the neuromuscular receptor organs were demonstrated in the young and adult rat masseter muscles either on the operated or unoperated side following the unilateral transection of the infraorbital nerve. The grade of the degeneration was intensive but quite similar in having no relation to the age of the rat when the operation was performed, while it increased drastically with time after the operation. On this base, it may be suggested that the sensory input coming from the various kinds of sensory receptors in the snout field do rather affect bilaterally the minor reflexive movements of the jaw. In other words, it can be said that the minor reflexive movements of the jaw might have been controlled by the sensory inputs coming from the snout sensory receptor organs. The definitely degenerated changes of the neuromuscular receptor organs in the masseter muscles should be regarded as disuse atrophy following the interception of the snout sensory input.

Animals↗
PubMed1984

Endogenous opioid peptides in intrapartum uterine blood.

Endogenous opioid peptides have consistently been reported to exert significant influence on several parameters of reproductive physiology, including tolerance to pain, release of prolactin, pleasurable behavior patterns, and appetite satiety. Immunoreactive endorphins measured in several hundred samples of postpartum uterine blood had a mean value of 190 pg/ml and a range of 60 to 520 pg/ml. Individual values in 100 mothers who were delivered at the Northwest Hospital failed to correlate with doses of postpartum pain medications, infant feeding patterns, and recorded estimates of maternal bonding behavior. Postpartum "blues" may be related to stress-induced depletion of endorphinergic systems.

Depression↗
PubMed1984

Circulating immune complexes in cervical cancer patients as detected by C1q binding.

In a retrospective study in women with cervical cancer, circulating immune complex levels were measured by radioimmunoprecipitation with 125I-C1q. Sera from 46 patients with cervical cancer and 35 normal controls were examined. Significantly higher levels of immune complexes were detected in cancer patients compared with controls. Mean value of binding capacity in patients was 49.8%, and by contrast, in the controls was 27.4% (two-tail test = 0). Increases in tumor mass were associated with high levels of circulating immune complexes. The presence of immune complexes in circulation statistically correlated with disease activity, however, the assay used still had limited value for diagnosis or aiding in therapeutic decisions. Nevertheless, the future holds promise for such uses.

Antigen-Antibody Complex↗
PubMed1984

Biologic properties of three newly established human esophageal carcinoma cell lines.

Three epithelial cell lines, CE-48T/VGH, CE-69T/-VGH, and CE-81T/VGH, were established from human squamous cell carcinoma of the esophagus. The cells were polygonal with a high nucleus-to-cytoplasm ratio. Many cells were multinucleate. Electron microscopy revealed the presence of tonofilaments and desmosomes. Chromosome analysis showed that these 3 cell lines were heteroploids of human origin. When transplanted into BALB/c (nu/nu) mice, CE-69T/VGH and CE-81T/VGH produced tumors, the histology of which proved to be carcinomas. All 3 cell lines secreted carcinoembryonic antigen. However, the secretion patterns were different. These 3 cell lines may provide useful models for the study of human esophageal cancer.

Animals↗
PubMed1983

Complement-mediated binding of monocytes to intermediate filaments in vitro.

An in vitro model for complement (C)-mediated monocyte binding to injured cells is described. This model is based on the property of cytoskeletal intermediate filaments (IMF) to directly and independently activate serum C via the classic pathway. Fixed monolayers of cultured fibroblasts, endothelial cells, and L 132 epithelial cells were each used as targets. The authors first subjected the target cells to limited detergent extraction in order to make permeable the plasma membrane, and then exposed them to normal human serum. Immunohistologic analysis demonstrated that this process permitted binding of clearly demonstrable amounts of C1q, C4, and C3 to cytoplasmic loci containing IMF. The target cells were then incubated for various lengths of time with peripheral blood mononuclear cells containing about 20% monocytes. Preferential binding of monocytes was demonstrated by histochemical and immunologic staining methods. Only 5% of the attached cells were B lymphocytes. By transmission electron microscopy the attached cells exhibited typical monocyte morphology. Attachment to target cells involved contact with areas rich in IMFs and led to signs of activation; both an increased number of cytoplasmic organelles and phagocytosis of target cell material were observed. Attachment of monocytes was clearly dependent on serum treatment of the targets; the ratio was 10:1 when compared with control experiments using target cells that had not been incubated with serum. It is reasonable to consider that bound monocyte-derived macrophages associate with activated C components, most likely C3b fragments or C1q, for which monocyte surface receptors have been established. This mechanism may be triggered in various inflammatory reactions involving cell and tissue injury and as an event in the final stages of macrophage-mediated removal of injured or nonviable cells.

Animals↗
PubMed1983

Isolation of an effective debriding agent from the stems of pineapple plants.

The stem of the pineapple plant contains, in addition to a number of proteases, particularly bromelain, a non-proteolytic component which is responsible for the complete bridement of experimental burns by an "enzymatic dissection" between the viable native and the non-viable denatured burn tissue. With very little scraping, using a tongue depressor, all of the eschar can be removed and a bed suitable for grafting results. This "Escharase" has a molecular weight of 45,000 daltons and is a trimer made up of three identical subunits weighing 15,000 daltons each; it has an isoelectric point of pH 6.04 and has no hydrolytic enzyme activity against normal protein substrates or various glycosaminoglycan substrates. It can be concentrated by membrane ultrafiltration in a molecular weight range between 30,000 and 50,000 daltons and be purified by isoelectric focusing. The biological activity of the Escharase is not dependent on sulfhydryl groups nor upon the contaminating bromelain activity. The Escharase activity varies enormously from preparation to preparation, but the ultrafiltration procedure tends to concentrate Escharase activity to a fairly constant amount.

Animals↗
PubMed1982

[A new human hepatoma cell line: establishment and characterization].

We have grown a human hepatoma cell line, designated as HA22T/VGH, from a 52-yr-old male hepatoma patient since July 1, 1980. This cell line has been subcultured more than 100 passages. The chromosome analysis of HA22T/VGH indicated that the chromosome numbers varied from 70 to 146, with the mode of 73. Methylcellulose soft agar assay showed that approximately 40% of the HA22T/VGH cells formed colonies. The HA22T/VGH produced tumors in nude mice. Histopathological studies of the tumor revealed the arrangement of hepatoma. Detected by the complement fixation method HA22T/VGH cells secreted ceruloplasmin, Factor B, C3, C4, Gc-globulin and alpha 1-acid-glycoprotein. These cells contained the liver associated enzymes: alanine amino transferase, tyrosine amino transferase and gamma-glutamyl transferase. HBsAg and alpha-fetoprotein were not detectable in the HA22T/VGH culture media or cell lysates by the radioimmunoassay.

Animals↗
PubMed1981

Immunoreactive endorphin peptides and prolactin in umbilical vein and maternal blood.

Immunoreactive endorphin peptides (ir EP) and prolactin (PRL) were measured by radioimmunoassay in venous blood from the umbilical cord of 86 neonates, 23 postpartum mothers, and 40 randomly selected blood bank donor control subjects. We also assayed these hormones in serosanguineous placental tissue fluid following delivery. The data suggest both ir EP and PRL are elevated during both processes and that placental chemistry may be implicated in blood levels of these hormones. Some biological and clinical aspects of placental opiates are discussed.

Endorphins↗
PubMed1981

Pancreatic beta-endorphin-like polypeptides.

Acid extracts of porcine pancreas acetone powders (but not of other tissues) have been shown to contain material which will react firstly in a radioimmunoassay for beta-endorphin, and secondly, compete with 3H-Naloxone and 3H-enkephalinamide in the radio-receptor assay. This material had a molecular weight of approximately 7,000 as judged by both P-10 and G-50 exclusion chromatography, even in the presence of 4 M urea. The G-50 partially purified and desalted fraction demonstrated a dose-dependent analgesia in mice and also influenced mouse behavior in vivo in a manner analogous to that produced by synthetic human beta-endorphin.

Animals↗