Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In recent years, many studies have suggested a direct role for alpha 2-macroglobulin (alpha 2M), a plasma proteinase inhibitor, in growth factor regulation. When coincubated in the presence of either trypsin, pancreatic elastase, human neutrophil elastase, or plasmin, 125I-insulin rapidly formed a complex with alpha 2M which was greater than 80% covalent. The covalent binding was stable to reduction but abolished by competition with beta-aminopropionitrile. Neither native alpha 2M nor alpha 2M pretreated with proteinase or methylamine incorporated 125I-insulin. Experiments utilizing alpha 2M cross-linked with cis-dichlorodiammineplatinum(II) indicated that 125I-insulin must be present during alpha 2M conformational change to covalently bind. A maximum stoichiometry of 4 mol of insulin bound per mole of alpha 2M and the short half-life of the alpha 2M intermediate capable of covalent incorporation were consistent with thiol ester involvement. Protein sequence analysis of unlabeled insulin-alpha 2M complexes, together with results of beta-aminopropionitrile competition, confirmed that insulin incorporation occurs via the same gamma-glutamyl amide linkage responsible for covalent proteinase and methylamine binding to alpha 2M. Although intact insulin apparently incorporated through its sole lysine residue on the B chain, we found that isolated A chain also bound covalently to alpha 2M. Phenyl isothiocyanate derivatization of the N-terminus had no effect on A-chain binding, supporting the possibility of heretofore unreported gamma-glutamyl ester linkages to alpha 2M.
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PMID:Mechanism of insulin incorporation into alpha 2-macroglobulin: implications for the study of peptide and growth factor binding. 170 57

HMB-45 is a monoclonal antibody directed against human melanoma cells and which stains epidermal and dermal melanoma cells, the junctional components of common and dysplastic melanocytic nevi, and melanocytes in fetal skin. In addition, melanocytes in a variety of reactive conditions have been shown to label with HMB-45, as have dermal melanocytes within Spitz and dysplastic nevi. No melanocytes in normal adult epidermis or in the dermis of common nevi have stained with HMB-45. In order to better understand the properties of this antibody, and of the melanocytes that react with it, we stained cultured human melanocytes grown in a variety of conditions. Melanocytes from human foreskins were grown for 2-3 weeks in MCDB 153 medium supplemented with insulin, epidermal growth factor, and bovine pituitary extract as a mixed population of keratinocytes and melanocytes. Some cells were transferred to basal medium MCDB 153 (unsupplemented) for periods ranging from 3-5 days, and a subset of these were returned to growth-factor supplemented medium. In all cases, S100 staining was used to confirm the presence of melanocytes. Melanocytes grown in complete medium showed strong granular cytoplasmic staining with HMB-45. Cells transferred to basal medium showed a markedly diminished staining intensity which was reversible within 3 days upon return of the cells to complete medium. The findings suggest that expression of the protein recognized by HMB-45 may be related to a growth factor present in complete medium, but missing from basal MCDB 153.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:HMB-45 monoclonal antibody recognizes an inducible and reversible melanocyte cytoplasmic protein. 176 83

The intranasal administration of powder formulations containing insulin and the permeation enhancer sodium tauro-24,25-dihydrofusidate (STDHF) were investigated in the sheep model. Both the hypoglycemic response and the serum insulin levels increased as the mole ratio of STDHF to insulin was increased from 0 to 16.8. In vitro dissolution rates of the powders and the rapid tmax (approximately 5 min) observed after intranasal administration suggest that the absorption of insulin is not dissolution limited. The bioavailabilities (F) of the powder formulations ranged from 2.9 to 37.8%. In comparison, the F values for a solution formulation with a STDHF:insulin ratio of 8.4 administered as either drops or spray were 15.7 and 37.4%, respectively. The permeation enhancer STDHF increases mucosal permeability and reduces the average molecular weight of the insulin species.
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PMID:Intranasal bioavailability of insulin powder formulations: effect of permeation enhancer-to-protein ratio. 179 29

The urinary excretion of chromium, copper and manganese was determined in 185 diabetics and in an equal number of control subjects by measuring the concentration of each of these metals using electrothermal atomic spectrophotometry and dividing the values by the urinary concentration of creatinine (creat) in each subject. The mean (SEM) values for the overall diabetics and the control group were 2.32 (0.17) and 2.62 (0.22) mumol Cr/mole of creat, 76.5 (5.5) and 73.9 (6.1) mumol Cu/mole of creat, and 3.56 (0.44) and 2.66 (0.3) mumol Mn/mole of creat, respectively. There was no correlation between the urinary excretion of any of the metals examined and age or sex of either group. While the cardiovascular or ophthalmologic diseases associated with diabetes did not influence the excretion of any of these metals, significantly higher urinary excretion of Cu was exhibited by diabetics with neuropathy (p < 0.0027) or infections (p < 0.014) than by those without. Also, diabetics with liver disorders or those who were not treated with insulin excreted significantly more Mn than did their diabetic counterparts.
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PMID:Urinary excretion of chromium, copper, and manganese in diabetes mellitus and associated disorders. 184 23

Administration of cortisone and thyroxine produced adult-type increase in the activities of soluble and membrane-bound gamma-glutamyltranspeptidase (gamma-GTP) in suckling rat intestine. Membrane-bound enzyme activity remained unaltered while the soluble enzyme activity was reduced (27%) in insulin-injected pups. Kinetic analysis revealed that the observed changes in the enzyme levels were a consequence of altered Vmax with no change in apparent Km. A 2-fold increase in the Km value was observed in adult gamma-GTP activity compared to that of suckling animals. Membrane-bound and soluble gamma-GTP yielded similar values of the Ea (9.7-13.1 kcal/mole) but exhibited apparent differences in heat stability in the control and hormone-injected groups. Leucine-amino peptidase(LAP) activity was reduced to adult levels in insulin-treated suckling animals. Thyroxine- and cortisone-treatment did not affect soluble activity but significantly (P less than 0.001) augmented the membrane-bound LAP levels. This increase was due to enhanced (54-82%) Vmax with no change in Km. The observed decrease in LAP activity in response to insulin was due to reduced Vmax. There was no change in Ea (8-11.6 kcal/mole) except the value was raised to 19.1 kcal/mole in cortisone-injected pups. Both the soluble and membrane-bound LAP activities were quite resistant to heat inactivation upto 30 min at 60 degrees C except in weanling rats. Thus, the kinetic behaviour of normally developed and precociously induced gamma-GTP and LAP is essentially similar but there are apparent differences in the mode of action of insulin, cortisone and thyroxine in affecting the development of these enzymes.
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PMID:Kinetic properties of gamma-glutamyltranspeptidase and leucine-amino-peptidase in developing rat intestine: effect of hormones. 197 48

A nonperturbing 13C nuclear magnetic resonance (NMR) method was used to monitor the equilibrium distribution of carboxyl 13C-enriched fatty acids (FA) between distinct binding sites on human serum albumin, native human lipoproteins, and/or phospholipid model membranes, under conditions that mimic the normal and diabetic human circulation. Two variables pertinent to the diabetic circulation were examined: FA/albumin mole ratio (as elevated in insulin deficiency and/or nephrosis) and pH (as decreased in acidosis). 13C NMR spectra for samples containing carboxyl 13C-enriched palmitate, human serum albumin, and phospholipid vesicles or native lipoproteins (all samples at pH 7.4, 37 degrees C) exhibited up to six carboxyl NMR resonances corresponding to FA bound to distinct binding sites on albumin and nonalbumin components. When the sample FA/albumin mole ratio was 1, three FA carboxyl resonances were observed (182.2, 181.8, and 181.6 ppm; designated peaks beta, gamma, and beta', respectively). These resonances corresponded to FA bound to three distinct high-affinity binding sites on human serum albumin. When the sample mole ratio value exceeded 1, additional carboxyl resonances corresponding to FA bound to phospholipid vesicles (179.0 ppm, peak phi), lipoproteins (180.7 ppm, peak sigma), and lower affinity sites on albumin (183.8 ppm, peak alpha; 181.9 ppm, peak gamma'), were observed. The intensity of peaks phi and sigma increased with increasing mole ratio or decreasing pH. Using Lorentzian lineshape analysis, the relative mole quantities of FA bound to albumin and nonalbumin binding sites were determined. Plots of the fraction of FA associated with nonalbumin components as a function of FA/albumin mole ratio were linear and extrapolated to the abscissa at a mole ratio value of 1. This pattern of FA distribution was observed regardless of the type of nonalbumin acceptor used (phospholipid vesicles, human high- or low-density lipoproteins) or the type of FA used (palmitate, oleate, or stearate), and provided evidence for negative cooperativity for human serum albumin upon binding of 1 mol of FA per mole albumin. These in vitro NMR results suggest that the threshold FA/albumin mole ratio value for alterations in FA distributions in the human circulation may be 1, rather than 3, as previously held. The pathophysiological implications of these findings are discussed.
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PMID:Fatty acid distribution in systems modeling the normal and diabetic human circulation. A 13C nuclear magnetic resonance study. 201 May 53

Suckling rat intestine contains 35 and 65% of the cytosolic and membrane-bound alkaline phosphatase (AP) activities. The corresponding values for sucrase were 20 and 80% respectively. The amount of the soluble enzymes was reduced to 7-11% in adult rat intestine. Administration of cortisone, thyroxine or insulin to suckling animals induced adult type distribution of the enzymes. There were apparent differences in kinetic characteristics of soluble and brush border enzymes, but the kinetic properties of the normally developed and hormone-induced AP and sucrase were essentially similar. This suggested identical nature of these enzymes under these conditions. A biphasic Arrhenius plot was obtained for AP in weaned and hormone injected pups with a break point around 18 degrees C, while the soluble enzyme yielded a monophasic curve (Ea = 8-11 kcal/mole). Arrhenius plot for sucrase was monophasic in the suckling, hormone-injected and adult rat intestine (Ea = 8.3-15.1 kcal/mole). Membrane-bound enzymes were generally labile, while soluble enzyme activities were stable to heat treatment (sucrase at 50 degrees C and AP at 60 degrees C) in various experimental groups.
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PMID:Kinetic characteristics of soluble and brush border alkaline phosphatase and sucrase activities in developing rat intestine: effect of hormones. 235 52

Normal human cells, cells from nonmalignant proliferative lesions, and primary and metastatic tumor cells can be maintained in vitro and analyzed for requirements for growth in chemically defined media. The human melanocytic cell system with normal melanocytes, precursor nevus cells, and primary and metastatic melanoma cells has been extensively studied for the phenotypic properties of the cells, including their requirements for exogenous growth factors and other mitogens. In high calcium-containing W489 medium, normal melanocytes require four supplements: IGF-I (or insulin); bFGF, TPA, and alpha-MSH. Nevus cells are largely independent of bFGF. Depletion of TPA from medium is not as detrimental to nevus cells as it is to melanocytes, but the phorbol ester is still essential for maintenance of the typical nevic phenotype. Primary melanoma cells require at least one growth factor, IGF-I (or insulin), for continuous proliferation. On the other hand, metastatic cells of melanoma as well as of carcinomas of colon and rectum, bladder, ovary, and cervix are able to proliferate after a short adaptation period in medium depleted of any growth factors and other proteins. Doubling times of metastatic tumor cells in protein-free medium are only 30-60% longer than in FCS-containing medium. The growth autonomy of human tumor cells is apparently due to the endogenous production of growth factors. Likely candidates for autocrine growth stimulation of human tumor cells are TGF-alpha, TGF-beta, and PDGF. Melanoma and colorectal carcinoma cells express functional EGF/TGF-alpha receptors, and produce TGF-alpha, indicating that this growth factor is produced for autocrine stimulation. In addition to the use of anti-growth factor antibodies, other strategies for the inhibition of autocrine growth stimulation include mAbs to growth factor receptors, soluble receptors, receptor-mimicking antiidiotype antibodies, and active immunization against growth factors. Whether any of these therapeutic approaches is clinically feasible will need to be determined in extensive preclinical investigations.
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PMID:Growth-regulatory factors for normal, premalignant, and malignant human cells in vitro. 240 78

Calmodulin is a substrate for insulin-receptor kinase obtained from rat adipocytes and hepatocytes and human placenta. In this study, we demonstrate that insulin stimulates the phosphorylation of calmodulin via insulin receptors partially purified from rat skeletal muscle. Phosphorylation of calmodulin was maximal in the presence of Mg2+ and insulin and the absence of Ca2+. Free-Ca2+ concentrations greater than 0.1 microM progressively inhibited phosphorylation with almost total inhibition at 200 microM Ca2+. Insulin-stimulated phosphorylation of calmodulin was dose dependent and saturable with half-maximal effect obtained at approximately 5 x 10(-10) M insulin. There was an absolute requirement for certain basic proteins, e.g., polylysine or protamine sulfate, to obtain phosphate incorporation into calmodulin. Polylysine stimulated the phosphorylation of calmodulin independently of insulin, but this was increased up to sixfold by the addition of insulin. Phosphate incorporation into calmodulin increased with increasing concentration of the substrate up to a saturating concentration of 2.4 microM. The Km for calmodulin was approximately 0.2 microM. Up to 0.15 mol of phosphate was incorporated per mole of calmodulin with tyrosine the predominant amino acid phosphorylated. The observations that calmodulin is phosphorylated by insulin-receptor kinase from all three classic target organs for insulin confirm that calmodulin is a general substrate for this kinase and suggest that Ca2+ and calmodulin may be components of the insulin-signaling mechanism.
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PMID:Calmodulin as substrate for insulin-receptor kinase. Phosphorylation by receptors from rat skeletal muscle. 253 26

To overcome the difficulties encountered in quantifying the insulin receptor number by Scatchard analysis, a radioimmunoassay (RIA) for the human insulin receptor (hIR) has been developed that uses an antibody raised against a synthetic peptide (Gly-Lys-Lys-Asn-Gly-Arg-Ile-Leu-Thr-Leu-Pro-Arg-Ser-Asn-Pro-Ser) corresponding to the carboxyl terminal of the hIR. A second peptide (Tyr-Gly-Arg-Ile-Leu-Thr-Leu-Pro-Arg-Ser-Asn-Pro-Ser) was used as a standard and allowed preparation of monoiodinated derivative of theoretical specific activity for use as the radioactive ligand. The assay is specific, highly reproducible, and sensitive, with a detection limit of 10 fmol of receptor. One mole of purified receptor, measured by Scatchard analysis or amino acid analysis, is read as one mole of receptor in the RIA with peptide being the standard. The assay is effective with receptor from multiple sources and could determine the decrease in number of insulin receptors seen in IM-9 lymphocytes after treatment with insulin (downregulation).
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PMID:Peptide-based radioimmunoassay for insulin receptor. Detection of insulin-stimulated downregulation in IM-9 lymphocytes. 266 3


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