Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The immune system is a potential target of environmental toxins. Impairment of immune function could have a disastrous effect upon the affected individual. We had the unique opportunity to study the results of a prolonged exposure to TCDD (2,3,7,8-tetrachlorodibenzo-P-dioxin) in rhesus monkeys and their offspring. Subsequently, we performed similar studies on humans exposed to the nematode pesticide, Aldicarb. This report summarizes those previous studies. In the monkeys, no major deficits of the immune system were found and the animals did not have excessive numbers of infections. However, at higher doses of dietary TCDD (25 ppt), only 22% of the offspring survived to 1 year of age. Thus, the failure to demonstrate effects on the young may simply relate to the essential equivalence of the lethal to an immunosuppressive dose. In humans, exposure to the acetylcholinesterase inhibitor, Aldicarb, was received through contaminated well water. The known exposure was for at least 1 year and could have been as long as 5 years. Various tests of the immune system, including lymphocyte subset counts, proliferative responses, total immunoglobulin levels and specific antibody responses did not reveal immunodeficiency. Increases in the numbers of CD8 positive T lymphocytes was observed. There was no evidence of any increase in clinical illness in the exposed compared with the control group.
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PMID:Effects of environmental toxins on lymphocyte function: studies in rhesus and man. 204 62

When platelet counts were compared in 1986 and 1992 in 117 anti-HIV antibody positive and negative hemophilia patients, a clear decrease was found in the positive group. In 1992 platelet counts < 150 x 10(9) were present in 23.5% of the positive group in contrast to 5.8% of the negative group. Comparing platelet counts with other clinical parameters, a positive correlation was found with cholinesterase and a negative correlation with IgG in both the positive and negative groups, while negative correlations with beta 2-microglobulin and platelet-associated IgG were found in only the positive group. These findings implicate the chronic liver dysfunction present in hemophilia patients, apart from HIV infection, in the decrease in platelet counts, with immunodeficiency playing an additional role in the positive group. In the treatment of a hemophilia B patient showing decreased platelet counts, these counts increased consistent with the administration of Acyclovir and Zidovudine. It was demonstrated that HSV-1 and HIV-1 antigen are present on the soluble platelets of this patient and are recognized by antibodies in the patient's serum.
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PMID:[Thrombocytopenia in HIV-1 seropositive hemophiliacs]. 831 32

1. Pentamidine is routinely used to reduce the incidence of Pneumocystis carinii pneumonia in patients infected with human immunodeficiency virus, but it has been described as inducing pulmonary adverse effects, such as cough and bronchospasm. 2. In this paper we have investigated the effects of pentamidine on guinea-pig isolated main bronchi and human isolated bronchi. Pentamidine induced a concentration-dependent contraction in both preparations with pD2 values of 9.64 +/- 0.07 (n = 8) and 9.73 +/- 0.06 (n = 8) and a maximal effect (Emax) of 40 +/- 4% and 34 +/- 5% of the response to acetylcholine (1 mM) in guinea-pig and human bronchi respectively. Atropine (0.01 to 0.1 microM) and the muscarinic M3 receptor antagonist, hexahydro-siladiphenidol (0.1 and 1 microM) inhibited pentamidine-induced concentration-responses in both preparations in a non-competitive manner, whereas only high concentrations of the M1 receptor antagonist pirenzipine (1 microM) inhibited pentamidine concentration-response curves. 3. The cholinesterase inhibitor, tacrine (1 microM), potentiated the effect of pentamidine; in contrast, morphine inhibited pentamidine-induced responses. 4. The bronchoconstrictor effect of pentamidine on guinea-pig and human isolated bronchi was not modified by the H1 histamine receptor antagonist, mepyramine, by indomethacin or by the neurokinin NK1 and NK2 receptor antagonists, CP-96,345 and SR 48969 respectively, suggesting that neither histamine receptor stimulation, arachidonic acid derivative formation, nor tachykinin release are involved in pentamidine-induced contraction of human and guinea-pig airways. 5. Our overall results suggest that pentamidine induces contraction of guinea-pig and human isolated bronchi through prejunctional cholinergic nerve stimulation.
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PMID:Indirect muscarinic receptor activation by pentamidine on airway smooth muscle. 893 15

Biotransformation of rifabutin, an antibiotic used for treatment of tuberculosis in patients infected with the human immunodeficiency virus (HIV), and its interactions with some macrolide and antifungal agents were studied in human intestinal and liver microsomes. Both liver and enterocyte microsomes metabolized rifabutin to 25-O-deacetylrifabutin, 27-O-demethylrifabutin, and 20-, 31-, and 32-hydroxyrifabutin. The same products (except 25-O-deacetylrifabutin) were formed by microsomes from lymphoblastoid cells that contained expressed CYP3A4. The apparent Michaelis-Menten constant (Km); approximately 10 to 12 mumol/L) and maximal velocity (Vmax; approximately 100 pmol/min/mg of protein) values for CYP-mediated metabolism were similar in liver and enterocyte microsomes. Deacetylation of rifabutin (Km approximately 16 to 20 mumol/L and Vmax approximately 50 to 100 pmol/min/mg of protein) was catalyzed by microsomal cholinesterase. Clarithromycin, ketoconazole, and fluconazole inhibited CYP-mediated metabolism of rifabutin in enterocyte microsomes equally or more potently than in liver microsomes but had no effect on cholinesterase activity. Azithromycin did not inhibit in vitro metabolism of rifabutin. This study provides evidence that CYP3A4 and cholinesterase are major enzymes that biotransform rifabutin in humans and that intestinal CYP3A4 contributes significantly to rifabutin presystemic first-pass metabolism and drug interactions with macrolide and antifungal agents.
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PMID:Metabolism of rifabutin in human enterocyte and liver microsomes: kinetic parameters, identification of enzyme systems, and drug interactions with macrolides and antifungal agents. 916 17

We have developed an enzyme immunoassay to measure nevirapine (NVP) in plasma and peripheral blood mononuclear cells. Anti-NVP polyclonal antibodies were raised in rabbits by using a synthetic NVP derivative coupled to keyhole limpet hemocyanin as the immunogen, and the enzyme tracer was prepared by chemically coupling the NVP derivative with acetylcholinesterase. These reagents were used to develop a sensitive competitive enzyme immunoassay performed in microtitration plates with a 100-pg ml(-1) limit of detection and thus approximately 100 times more sensitive than previously published techniques. The plasma assay was performed directly without extraction (in this case, a 500-pg ml(-1) limit of detection was observed) on a minimum of 30 micro l of plasma. This assay shows good precision and efficiency, since recovery from human plasma and cell extracts spiked with NVP ranged between 87 and 104%, with coefficients of variation of <10%. A pharmacokinetic analysis of plasma NVP was performed for seven patients infected with human immunodeficiency virus (HIV), and it gave results similar to published findings. Intracellular concentrations of NVP were measured in cultured human T-lymphoblastoid cells and peripheral blood mononuclear cells from HIV-infected patients. The results indicated a very low intracellular/extracellular concentration ratio (0.134), thus demonstrating the absence of intracellular drug accumulation. This is the first intracellular assay of a nonnucleoside reverse-transcriptase inhibitor, and this method could be useful in monitoring plasma and intracellular NVP levels in HIV-infected patients.
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PMID:Sensitive enzyme immunoassay for measuring plasma and intracellular nevirapine levels in human immunodeficiency virus-infected patients. 1469 26

The protease inhibitor lopinavir (LPV; [1S-[1R*(R*), 3R*,4R*]]-N-[4-[[(2,6-dimethylphenoxy)-acetyl]amino]-3-hydroxy-5-phenyl-1-(phenylmethyl) pentyl] tetrahydro-alpha-(1-methylethyl)-2-oxo-1(2H)-pyrimide acetamide) is widely used in anti-human immunodeficiency virus (HIV) therapy. Knowledge of the plasma and intracellular concentrations of the drug would be useful for a better understanding of LPV action and for therapeutic monitoring. The aim of this study was to develop a sensitive and specific immunoassay for LPV in plasma and cells. Anti-LPV polyclonal antibodies were raised in rabbits using a synthetic LPV derivative coupled to keyhole limpet hemocyanin (KLH) as immunogen. The enzyme tracer was prepared by chemically coupling the LPV derivative with acetylcholinesterase. These reagents were used to develop a competitive enzyme immunoassay (EIA) performed in microtitration plates. The assay was performed on a minimum of 50 microl of plasma or 2 x 10(6) cells. It showed good precision and efficiency in as much as recovery from human plasma and cell extracts spiked with LPV ranged between 87% and 104%, with coefficients of variation of less than 10%. The limit of detection (LOD) was 100 pg/ml, i.e., a value at least 10 times lower than those currently achieved using previously described techniques. Cross-validation with high-performance liquid chromatography (HPLC) revealed a good correlation between methods (r2=0.96). Intracellular concentrations of LPV were measured in cultured human T lymphoblastoid cells (CEM). A pharmacokinetic analysis of plasma and intracellular LPV was performed on a healthy volunteer, and measurements were done in patients infected with HIV. The results obtained indicated a high intracellular/extracellular concentration ratio in cultured cells (19.3) but not in cells from HIV patients (1.3). In contrast, in peripheral blood mononuclear cells (PBMC) the accumulation of ritonavir (RTV) was six times higher than LPV. To date, this is the first reported immunoassay for LPV, and this method is sensitive enough for monitoring plasma and intracellular LPV levels in HIV-infected patients and for intracellular studies.
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PMID:An enzyme immunoassay for the quantification of plasma and intracellular lopinavir in HIV-infected patients. 1562 9

Although FDA-approved Alzheimer's disease (AD) treatment strategies (cholinesterase inhibitors and memantine) offer proven benefits, providers recognize unmet needs beyond what is currently available. Consequently there is a significant use of anecdotal yet unproven combinations for treating AD in practice. Based on the best evidence, combination drug therapy is the standard of care for treating other medical conditions such as malignancies, human immunodeficiency virus (HIV), and hypertension. We review recent combination drug therapy studies in AD. To date, the best evidence-based combination strategy is for moderate-to-severe AD, in which the addition of memantine to stable donepezil therapy was found to benefit cognition, behavior, and function. In milder stages of AD, the benefit of combination drug therapy has not been demonstrated. This review highlights the urgent need to systematically test additional rational drug combinations and the need for future trials to enroll adequate sample sizes and utilize relevant and sensitive outcome measures.
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PMID:Combination drug therapy for Alzheimer's disease: what is evidence-based, and what is not? 1594 60

We have developed an enzyme immunoassay to measure atazanavir (ATV) levels in plasma and cells. Anti-ATV polyclonal antibodies were raised in rabbits by using a synthetic ATV derivative coupled to bovine serum albumin as the immunogen, and the enzyme tracer was prepared by chemically coupling the ATV derivative with acetylcholinesterase. These reagents were used to develop a sensitive competitive enzyme immunoassay performed in microtitration plates, and the lowest limit of quantification was 150 pg/ml, which is about 10 times more sensitive than previously published techniques. The plasma assay was performed, after a simple methanol extraction, with a minimum of 30 microl of plasma. This assay showed good precision and efficiency, since the rates of recovery from human plasma and cell extracts spiked with ATV ranged form 93 to 113%, with coefficients of variation of less than 10%. ATV concentrations were measured in peripheral blood mononuclear cells incubated with various ATV concentrations and in CEM cells in the absence or presence of antiretroviral drugs and drug transporter inhibitors. The results indicated a dose-dependent uptake (intracellular concentration/extracellular concentration ratio range, 0.04 to 19). A significant increase in the accumulation of ATV was noticed in the presence of P-glycoprotein and MRP1 inhibitors (dipyridamole, inter alia). Interestingly, efavirenz significantly increased the baseline accumulation of ATV, whereas nevirapine induced a marked reduction. This new enzyme immunoassay for measuring plasma and intracellular ATV levels was fully validated and provides an inexpensive and useful tool for routine therapeutic drug monitoring. Moreover, in vitro results suggested the implication of drug transporters and interactions with other antiviral drugs that should be further explored in human immunodeficiency virus-infected patients.
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PMID:Quantitative immunoassay to measure plasma and intracellular atazanavir levels: analysis of drug accumulation in cultured T cells. 1711 61

A century has passed since the discovery of the first neurotransmitter, acetylcholine, in 1914. Extensive research on acetylcholine and its function has provided us with important options to treat the formerly intractable neuromuscular disease myasthenia gravis (MG). In the first days of treatment for MG, acetylcholine esterase inhibitors are administered, which is only a symptomatic therapy. After overwhelming developments in immunology, the immunological mechanisms of MG at the molecular or genetic level were recognized. Destruction of the acetylcholine receptors through autoimmune attacks plays a pivotal role in the evolution of MG. Thus, a mainstay of the newly developing treatments for MG are effective immunosuppression or immunomodulation. However, these therapeutic approaches are still "symptomatic", and target immunological rather than specific myasthenic symptoms. Immunomodulation may result in fatal immunodeficiency. From this point of view, although they are somewhat removed from first-line MG treatment (cholinesterase inhibitors), future drug development should focus on the cancellation of autoimmunity in MG patients.
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PMID:[Myasthenia gravis and acetylcholine]. 2480 68

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