Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The combined use in peptide synthesis of the Fmoc-group with methyl, benzyl or p-nitro benzyl esters is not practical because of the elimination of the Fmoc-group under basic conditions and by catalytic hydrogenation. Nevertheless the solution synthesis of peptides requires those combinations in some cases. For this purpose we have investigated enzymatic hydrolysis of some tri and tetrapeptide esters. The hydrolysis were carried out under pH-control. We measured deprotection of the carboxyl group by thermitase, porcine liver esterase, carboxypeptidase A and alpha-chymotrypsin. The main problems are to suppress proteolytic degradation of the peptide bond and to bring the protected peptides into solution. To solve both problems we used dimethylformamide and dimethylsulfoxide as cosolvents. The ratios between esterolytic and proteolytic activity were estimated under various cosolvent concentrations. Advantages of this method are to avoid side reactions of alkaline instable side chains (e.g. asparagine, glutamine), cleavage of base labile protecting groups and racemization by alkaline saponification. The enzymatic deprotection was followed by HPLC, HPTLC and titration. On a preparative scale this method gives good yields and sufficiently pure products.
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PMID:Hydrolysis of peptide esters by different enzymes. 144 67

Lymph nodes from 21 cases of generalized mastocytosis were studied histologically to confirm or exclude mast cell infiltration, and to investigate their micro-architecture. Mast cell infiltrates were detected in 17 (80%) of the lymph nodes and were found mainly in the medullary cords and sinuses. Diffuse infiltration was seen in 14 cases and focal infiltration in three cases. The following pathological findings were frequently observed: germinal centre hyperplasia (n = 14), which is probably a nonspecific finding; and hyperplasia of small blood vessels, which sometimes resembled high endothelial venules (14), eosinophilia (8), plasmacytosis (7) and collagen fibrosis (6), all of which may well be related to the effects of mediators released by mast cells. Infiltrates of acute or chronic myeloid leukaemia were seen in six lymph nodes. Division of the cases into two prognostically different groups, i.e. systemic mastocytosis, in which the skin lesions of urticaria pigmentosa are present and the prognosis is favourable, and malignant mastocytosis, in which there is no cutaneous involvement and the prognosis is poor, revealed that all six lymph nodes exhibiting leukaemic infiltrates came from the malignant mastocytosis group; eosinophilia, plasmacytosis and fibrosis were seen significantly more often in malignant than in systemic mastocytosis, but blood vessel hyperplasia and germinal centre hyperplasia were encountered with the same high frequency in both groups; and mast cell atypia tended to be more pronounced in malignant mastocytosis; this diagnosis could therefore easily be missed without naphthol AS-D chloroacetate esterase staining.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lymph node findings in generalized mastocytosis. 145 27

This study examined plasma exudation into the bronchial lumen after allergen challenge. A novel low-trauma technique was developed to challenge and lavage a medium-sized lingular or middle lobe bronchus. Eleven subjects with challenge-assessed pollen-sensitive asthma were allocated to fiberbronchoscopy in the supine position. In the control bronchus 0.5 ml diluent was instilled. The bronchus was occluded proximally 3 min later by inflation of a balloon, and lavage was carried out twice with 25 ml saline. Incremental doses of allergen solution (0.5 ml) were then instilled in the contralateral lung. The challenge continued until a clearly visible bronchial reaction occurred and was immediately followed by the same lavage as on the control side. The lavage liquids were analyzed for the presence of plasma exudation and mast cell activation indices. On the allergen-challenged side, tryptase, reflecting mast cell activation, was increased by 150% (p < 0.01) compared with the control side. Fibrinogen (mol wt 340,000), reflecting large protein exudation, was increased by 840% (p < 0.05), and N-alpha-tosyl-L-arginine-methyl esterase activity, reflecting both large protein exudation and mast cell activation, increased by 480% (p < 0.01). The level of albumin (mol wt 69,000), the major luminal protein under baseline conditions, increased but not significantly. We conclude that activation of mast cells and luminal entry of little sieved plasma exudates occur early after endobronchial allergen provocation in human subjects with allergic asthma.
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PMID:Bronchial exudation of bulk plasma at allergen challenge in allergic asthma. 145 71

Mast cell chymase stimulates secretion from cultured airway gland serous cells and hydrolyzes bronchoactive peptides in vitro. To explore the likelihood of these interactions occurring in situ, we examined the distribution and concentration of chymase-containing mast cells near glands and smooth muscle of major human bronchi from eight individuals without known airway disease. Total airway mast cells and the subset of mast cells containing chymase were detected by staining for methylene blue metachromasia and chloroacetate esterase activity, respectively. The percentage of chymase-containing mast cells was found to differ strikingly among bronchial tissue compartments. Near glands, for example, the concentration of chymase-positive mast cells (640 +/- 120 cells/mm3) was 73 +/- 9% that of total mast cells (910 +/- 130 cells/mm3), whereas in smooth muscle the concentration of chymase-positive mast cells (450 +/- 200 cells/mm3) was only 14 +/- 4% that of total mast cells (2920 +/- 620 cells/mm3). Of all chymase-containing mast cells in the airway subepithelium, 30 +/- 4% were located within 20 microns of submucosal glands. Although the percentage of chymase-containing cells varied, the absolute concentration of chymase-containing mast cells was similar in all compartments. These results reveal a differential distribution of mast cell subpopulations in human airway and suggest that mast cells containing chymase are near gland and smooth muscle targets.
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PMID:Distribution of chymase-containing mast cells in human bronchi. 158 24

Previous studies showed that lung and skin mast cells do not contain eosinophil granule major basic protein (MBP). However, MBP has been localized by immunofluorescence to mast cells from a recently established human mast cell line. Analysis of MBP in human mast cell-1 cell lysates by radioimmunoassay showed immunochemical similarity to eosinophil MBP as judged by comparison of dose-response regression lines. Based on these findings and other new information about mast cell heterogeneity, we tested whether mast cells contain MBP. Mast cells were preserved in Carnoy's fixative and were identified by staining with rhodamine-conjugated avidin or for chloroacetate esterase or aminocaproate esterase activity. MBP was localized by immunofluorescence to mast cells in 6 of 7 nasal polyps, 4 of 4 ileal tissue specimens, and 12 of 14 cutaneous mastocytosis specimens. Furthermore, by immunoelectron microscopy MBP was localized to mast cell granules in cutaneous mastocytosis lesions. In contrast, normal skin mast cells preserved in Carnoy's fixative did not contain MBP. After injection of MBP into normal skin and fixation in Carnoy's fluid, mast cells became MBP-positive within 3 minutes, suggesting that endocytosis of MBP by mast cells had occurred. These results suggest that human mast cells in several tissues may sequester toxic eosinophil proteins by endocytosis.
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PMID:Sequestration of eosinophil major basic protein in human mast cells. 168 35

Limited proteolysis of carboxypeptidase A from bovine pancreas with subtilisin Carlsberg generates a stable intermediate, carboxypeptidase S, whose esterase and peptidase activities are increased and decreased, respectively, under standard assay conditions. Carboxypeptidase S was isolated by affinity chromatography. Sequence analysis shows that it is cleaved solely at the Ala154-Gly155 bond. Its enzymatic properties were determined under stopped-flow conditions with Dns-Gly-Ala-Phe and its ester analogue Dns-Gly-Ala-OPhe. For both substrates, the Km values are increased 30-40-fold. The kcat value for peptide hydrolysis is virtually unaffected whereas that for ester hydrolysis is increased 10-fold. The magnitude of the Km effect is equivalent to a loss of 9 kJ/mol of binding energy and likely reflects a disruption of the network of hydrogen bonds that links Tyr-248 and Arg-145 to the backbone carbonyls of Ala-154 and Gly-155. The difference in kcat effects for the two substrate classes is related to differences in the chemical nature of the rate-determining step. Product release is rate determining for catalytic hydrolysis of ester substrates, and hence, the increase in kcat indicates that dissociation of products is facilitated as a result of the Ala154-Gly155 bond scission. The changes in enzymatic activity accompanying limited proteolysis are due to conformational alterations in the vicinity of the active center of the molecule. The affinity of a monoclonal antibody, mAb 100, directed toward the antigenic determinant located between residues 209 and 218 in carboxypeptidase A is diminished considerably for carboxypeptidase S.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Catalytic and conformational changes induced by limited subtilisin cleavage of bovine carboxypeptidase A. 169 55

In some persons, cold, dry air (CDA) provokes symptoms of rhinitis that are associated with increased levels of histamine and other inflammatory mediators in nasal lavages. Because the patterns of mediators released during the early reaction to antigen and CDA-induced rhinitis are similar, we believe that mast cell activation is part of the reaction to CDA. In view of our previous finding that 1-wk pretreatment with topical steroids reduced symptoms and mediator release in the early nasal response to antigen of allergic subjects, we examined the effect of beclomethasone dipropionate on the response to CDA. Using a double-blind, crossover design, 84 micrograms of beclomethasone or placebo were administered in each nostril twice a day to 13 volunteers for 7 days prior to CDA challenge. The reaction to CDA was monitored by measuring the levels of histamine, N-alpha-p-tosyl-L-arginine methyl ester (TAME)-esterase activity and albumin in nasal lavages before and after provocation. Overall symptom scores, as well as scores for rhinorrhea and congestion, were also obtained. Cold, dry air challenge resulted in elevation over baseline of all parameters after placebo pretreatment. After beclomethasone, a significant reduction in histamine levels, but not in TAME-esterase activity or albumin levels or in number of symptoms, was observed. These results indicate that 1-wk pretreatment with beclomethasone affects mast cells, reducing histamine release after CDA, as it did in antigen-induced rhinitis. They also indicate that histamine may not be essential for the development of the immediate nasal reaction to CDA.
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PMID:Steroid-induced reduction of histamine release does not alter the clinical nasal response to cold, dry air. 170 10

TMV F-IV, isolated from the venom of Trimeresurus mucrosquamatus (TMV), caused rat hind-paw edema in a dose-dependent manner. The maximum hind-paw swelling was reached at 1.5-2 h after subplantar injection of TMV F-IV. The edematous response caused by TMV F-IV was suppressed by the s.c. pretreatment with diphenhydramine, methysergide, acetylsalicylic acid or dexamethasone, and by the subplantar co-injection with FPL 55712, a SRS-A antagonist, and BN 52021 or L 652731, both PAF antagonists. Polymorphonuclear (PMN) leukocyte infiltration appeared within 1 h and gradually increased in the rat paw 3-6 h after edema induction. Compound 48/80 or methotrexate pretreatment also inhibited paw edema caused by TMV F-IV. In isolated mast cells, TMV F-IV increased the formation of PGE2 and LTB4 and caused a dose-dependent release of histamine and beta-glucuronidase. Since there are no significant differences in paw edema and mast cell degranulation responses between TMV F-IV and its DFP-modified analogue, the esterase activity may not be necessary in these models. These results indicate that mast cells. PMN leukocytes and some inflammatory mediators such as histamine, serotonin, arachidonate metabolites and PAF are involved in TMV F-IV induced paw edema.
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PMID:Rat hind-paw swelling effect of an edema-producing protein isolated from Trimeresurus mucrosquamatus snake venom. 171 14

The presence of moderate amounts of histamine in the human placenta was confirmed (0.72 +/- 0.10 microgram/g wet weight), and the hitherto unknown storage site of this biogenic amine was elucidated. Mast cells were identified by their characteristic morphology, staining reactions and secretory activity measured in terms of histamine release. Human placental tissue contains 7.6 x 10(5) mast cells/g wet weight, identified by staining with toluidine blue or alcian blue, and these cells were positive for chloro-acetate-esterase. Light microscope studies of placental tissue stained with HRP-conjugated anti-human IgE demonstrated cells with a typical 'halo' effect indicating cell-bound IgE, and electron microscopy revealed cells containing membrane-bound electron dense granules. A single mast cell was calculated to contain approximately 1 pg of histamine. Enzymatic digestion of placental tissue with collagenase (1.5 mg/ml) yielded viable cell suspension. containing mast cells in a purity of 0.6% which exhibited a low spontaneous output of histamine (12%). Placental mast cells released histamine in a concentration dependent manner upon challenge with anti-human IgE and the calcium ionophore A23187. Also, unlike other human mast cells so far studied. with the exception of skin, those dispersed from human placenta were responsive to the polybasic secretagogue compound 48/80. These findings represent a novel source of human mast cells and, since placentas are readily available in quantity, such tissue is proposed as an ideal source of mast cells for biochemical and pharmacological use.
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PMID:A novel source of mast cells: the human placenta. 171 42

The effect of interaction of carboxypeptidase A (CPA) with three monoclonal antibodies, each with a different epitope (CP 10, CP 9, and CP 8), on the heat stabilization of enzymes is described. These monoclonal antibodies bind to CPA with a relatively high binding constant (approximately 10(8) M-1) and do not affect its catalytic properties. Intact carboxypeptidase A lost more than 95 and 90% of its esterase and peptidase activities within 120 min at 50 degrees C. The monoclonal antibodies increased the thermal stability of the enzyme by 90 and 60%, as compared with the peptidase and esterase initial activities, respectively. Binding of these monoclonal antibodies, alone or in pairs, to the enzyme epitopes that are supposedly involved in heat denaturation of CPA result in stabilization of the conformation of the enzyme. The effect of thermostabilization by monoclonal antibodies was more pronounced with respect to peptidase activity than to esterase activity, indicating that these activities follow different reaction mechanisms. Since properly selected monoclonal antibodies can be prepared against virtually any enzyme, their immunocomplexation may provide a general and convenient method for stabilization of the enzyme conformation to heat denaturation, without affecting the catalytic properties.
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PMID:Thermostabilization of carboxypeptidase A by interaction with its monoclonal antibodies. 176 Jan 32


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