Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lymphocytes were purified from peripheral blood of normal donors and patients with chronic lymphocytic leukemia (CLL) by Ficoll-Hypaque centrifugation. Adenylate cyclase activity, expressed as picomoles [(32)P]cyclic AMP generated per milligram protein per minute, was 57+/-4 in normals and 26+/-4 in CLL patients. Enzyme activity, expressed as picomoles [(32)P]cyclic AMP generated per 10(6) lymphocytes per minute, was 2.09+/-0.19 for normal lymphocytes and 1.10+/-0.16 for CLL lymphocytes. The differences between normal and CLL peripheral lymphocytes are highly significant (P < 0.001) with either method of calculating activity. Cyclic AMP levels (picomoles per 10(6) lymphocytes) also differed significantly: 1.38+/-0.29 for normals and 0.45+/-0.08 for CLL lymphocytes. Adenylate cyclase was assayed in lymphocytes enriched for bone marrow-derived (B) cells by removing E-rosetted thymus-derived (T) cells, and enriched for T cells by harvesting E-rosetted lymphocytes or by removing B cells with nylon wool absorption. Solutions to simultaneous equations gave the following calculated enzyme activities for pure B- and T-cell subpopulations (in picomoles [(32)P]cyclic AMP generated per milligram mg protein per minute): normal B, 196+/-22; normal T, 30+/-10; CLL B, 34+/-6; CLL T, 19+/-4. Thus. normal B-lymphocyte adenylate cyclase exceeds normal T-lymphocyte activity by more than sixfold, whereas in the case of CLL the enzyme activity in B lymphocytes is markedly reduced to levels comparable to T lymphocytes. The responses of lymphocytes to stimulation with the hormones prostaglandin E(1) and isoproterenol, and with NaF, were assessed. Compared with normal lymphocytes, enzyme activities were reduced in CLL lymphocytes incubated with these agents, but to a degree paralleling the reduced basal activities. Thus, the ratios between stimulated and basal adenylate cyclase levels in Ficoll-Hypaque-purified, normal lymphocytes were 2.3+/-0.1 after incubation with 10 muM isoproterenol, and 3.9+/-0.2 with 10 mM NaF, values which did not differ significantly from those obtained with CLL lymphocytes. When the enzyme activities calculated for purified T- and B-lymphocyte subpopulations were used to derive the stimulation ratios, the responses of normal and CLL T and B cells to these agents were also indistinguishable. The simplest explanation for these findings is a reduced number of normally responsive enzyme sites on the surface membranes of CLL lymphocytes, although alternative explanations are possible.
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PMID:Adenylate cyclase in thymus-derived and bone marrow-derived lymphocytes from normal donors and patients with chronic lymphocytic leukemia. 22 34

Receptor studies of human mononuclear leukocytes (MNLs) are complicated by the presence of contaminating platelets which have common receptors. A method was devised to produce MNLs free of platelets (less than 1%) and consists of sequential Ficoll-Hypaque gradients, a BSA gradient and a washing step. Lack of platelet contamination was confirmed by the following criteria: (a) microscopic evaluation using fluorescent dyes showed less than 1% platelets; (b) PGE1 stimulation of the leukocyte membrane adenylate cyclase required addition of exogenous GTP while the platelet cyclase did not; (c) immunoblots of the cells and membranes using antibodies strongly reactive against platelet membranes showed no reactivity against MNL membranes; (d) [3H]yohimbine showed no binding in MNL membranes under conditions where substantial binding to platelets was detected. MNLs were viable as judged by dye exclusion. PHA stimulation of lymphocytes was unimpaired. Plasma membranes of MNLs were prepared by brief sonication and fractionation on a sucrose step gradient. Binding studies using 3H-DHE, an alpha-receptor ligand, revealed no binding in MNLs from normal subjects (n = 6). By contrast, studies on cells from subjects with mild asthma with medication appropriately withheld (n = 8) showed low levels of binding (60-300 fmol/10(6) cells). The subtype and functionality of the putative alpha-receptors are being further evaluated.
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PMID:A method for the preparation of mononuclear cells devoid of platelet contamination and its application to the evaluation of putative alpha-receptors in normal and asthmatic subjects. 283 15

Platelet-activating factor (PAF) concordantly primes neutrophils (PMNs) for superoxide generation and elastase release. beta-Adrenergic stimulation of PMNs enhances cAMP-dependent protein kinase A (PKA) activity and has been shown to inhibit PAF-mediated NADPH-oxidase activity. PMN superoxide generation is thought to play a predominate microbicidal role, whereas elastase is known to mediate untoward PMN-endothelial interactions. We hypothesized that beta-adrenergic neutrophil stimulation has disparate effects on PAF-mediated PMN superoxide generation versus elastase release. Human PMNs were isolated using a standard Ficoll/Hypaque gradient. PMNs were then primed with PAF (200 nM) and activated with fMLP (1 microM). Subsets of PMNs were pretreated for 5 min with a beta agonist (10(-4) M isoprotereno) or an adenylate cyclase agonist (10(-5) M forskolin). Superoxide generation was determined by superoxide dismutase inhibitive cytochrome c reduction. Elastase activity was measured by the cleavage of n-methoxylsuccinyl-A-A-P-V-p-nitroanilide. Pretreatment with isoproterenol and forskolin yielded superoxide generation of 3.2 +/- 0.6 and 3.1 +/- 1.2 nmole/2.5 x 10(5) PMN/min compared to 9.0 +/- 0.6 nmole/2.5 x 10(5) PMN/min for PAF/fMLP alone, whereas isoproterenol and forskolin did not significantly affect PAF-mediated neutrophil elastase release, 22.4 +/- 5.3 and 24.0 +/- 3.6%, respectively, compared to 39.4 +/- 9.1% for PAF/fMLP alone. Disparate PMN signal transduction for superoxide generation versus elastase release may explain the SICU clinical paradox, in which patients are both susceptible to infection and vulnerable to PMN-mediated multiple organ failure.
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PMID:Beta-adrenergic stimulation down-regulates neutrophil priming for superoxide generation, but not elastase release. 924 67

cAMP regulates immune responses, and modifications in cAMP signaling are involved in the pathophysiology and treatment of depression. In the present report, basal and forskolin-stimulated levels of cAMP were determined in mononuclear cells and lymphocytes from control individuals and major depression patients. Twenty-eight patients between 24 and 59 years old were diagnosed for a major depression episode according to the criteria of the Structural Clinical Interview for Disorders of Axis I of the American Psychiatric Association. These patients presented a score of 25 for severity as measured by Hamilton Rating Scale of Depression (HAM-D), and 23 for Beck Inventory of Depression (BID). Control and patient mononuclear cells were isolated by Ficoll/Hypaque gradients and their lymphocytes were separated from the total mononuclear population by differential adhesion to plastic surface. The basal concentration of cAMP was 50% lower in mononuclear cells and lymphocytes from the depressed patients compared with the control subjects. The response to forskolin was significantly smaller in lymphocytes of major depression patients than in the controls, but no difference was evident in the mononuclear cell preparations. There was a significant increase in cAMP produced by 5HT in mononuclear cells from the control group, but not in their lymphocytes. This effect on mononuclear cells was reduced by the antagonist of 5HT1A receptors, WAY-100,135. However, the simultaneous addition of a specific agonist of 5HT1A receptors, 8-hydroxy-(dipropylamino)tetralin (DPAT) and WAY-100,135 resulted in higher levels of cAMP than with the agonist alone. This effect probably indicates the blockade of 5HT1A receptors and action of 5HT1A agonist on the other subtypes of serotonin receptors expressed on human lymphocytes. This response was not observed in the patient's lymphocytes. In lymphocytes from major depression patients, serotonin and 8-hydroxy-(dipropylamino)tetralin significantly increased cAmp levels, which was slightly reduced by WAY-100,135. The present report indicates: (1) differential responses of immune cells from control individuals and depressed patients, with lower apparent adenylate cyclase activity in patient's cells; (2) variation in the population of cells, with responses to serotonergic agonists being lower in mononuclear cells and higher in lymphocytes from major depression patients; (3) increases of cAMP levels by serotonin and 5HT1A agonist in the patient's cells; and (4) evidence of impairment in serotonergic transduction systems in immune cells during depression.
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PMID:Differential cAMP levels and serotonin effects in blood peripheral mononuclear cells and lymphocytes from major depression patients. 1527 25