N-acetylation pharmacogenetics: a gene deletion causes absence of arylamine N-acetyltransferase in liver of slow acetylator rabbits.

The New Zealand White rabbit provides a widely used animal model for the human acetylation polymorphism, which confers marked interindividual variation in the effect and toxicity of numerous drugs, chemicals, and potential carcinogens. The relationship of a recently isolated cDNA clone, designated rnat, to genetically polymorphic arylamine N-acetyltransferase (NAT; acetyl-CoA:arylamine N-acetyltransferase, EC 2.3.

The human debrisoquine 4-hydroxylase (CYP2D) locus: sequence and identification of the polymorphic CYP2D6 gene, a related gene, and a pseudogene.

The debrisoquine-4-hydroxylase polymorphism is a genetic variation in oxidative drug metabolism characterized by two phenotypes, the extensive metabolizer (EM) and poor metabolizer (PM). Of the Caucasian populations of Europe and North America, 5%-10% are of the PM phenotype and are unable to metabolize debrisoquine and numerous other drugs. The defect is caused by several mutant alleles of the CYP2D6 gene, two of which are detected in about 70% of PMs.

Lidocaine metabolism in human liver microsomes by cytochrome P450IIIA4.

The metabolism of lidocaine to its major metabolite monoethylglycinexylidide (MEGX) was studied in human liver microsomes of 13 kidney transplant donors and of one patient with liver cirrhosis. Interindividual variation in metabolite formation was considerable. Biphasic kinetics indicated the involvement of at least two distinct enzymatic activities.

The CYP2D gene subfamily: analysis of the molecular basis of the debrisoquine 4-hydroxylase deficiency in DA rats.

The DA rat has been proposed as an animal model for the human debrisoquine 4-hydroxylase/bufuralol 1'-hydroxylase genetic deficiency. To determine the mechanism of this deficiency, we isolated and sequenced five cDNAs in the CYP2D gene subfamily including a new IID1 allele and two cDNAs of novel P450s, designated IID3 and IID5. IID3 and IID5 cDNA-deduced amino acid sequences contained 500 and 504 residues with calculated molecular weights of 56,683 and 57,081, respectively.

cDNA cloning and sequence and cDNA-directed expression of human P450 IIB1: identification of a normal and two variant cDNAs derived from the CYP2B locus on chromosome 19 and differential expression of the IIB mRNAs in human liver.

A cDNA designated hIIB1, representing the entire coding sequence of a P450 in the IIB gene family, was isolated from a human liver lambda gt11 library by using the rat IIB1 cDNA as a probe. The hIIB1 protein, deduced from the cDNA sequence, contained 491 amino acids, had a calculated molecular weight of 56,286, and displayed 76% amino acid similarity with the rat IIB1 protein. Expression of this cDNA, using the vaccinia virus system, yielded a P450 that had a reduced CO-binding spectrum with an absorption maximum of 452 nm.

[Placebos and nocebos].

Placebo effects are common in the treatment of pain. This paper summarizes present knowledge on the placebo response, its frequency, its problems, the suspected mechanisms of placebo effects and ethical and legal aspects of the intentional application of placebos. Clinical situations are described in which the use of placebos may be considered and conditions for its critical application are proposed.

Oxidation of midazolam and triazolam by human liver cytochrome P450IIIA4.

The metabolism of midazolam and triazolam to their 1'-hydroxy and 4-hydroxy metabolites was studied in microsomes of 15 human livers. The formation of both metabolites was inhibited by more than 90% by an antiserum directed against a pregnenolone 16 alpha-carbonitrile-inducible cytochrome P450 (P450PCN1) of rat liver. Moreover, midazolam hydroxylase activity was immunoprecipitated from solubilized human microsomes with polyclonal antibodies against rat P450PCN1 and the closely related human isozyme P450NF.

Cytochrome P-450 hPCN3, a novel cytochrome P-450 IIIA gene product that is differentially expressed in adult human liver. cDNA and deduced amino acid sequence and distinct specificities of cDNA-expressed hPCN1 and hPCN3 for the metabolism of steroid hormones and cyclosporine.

Immunoblotting analysis of human liver microsome preparations revealed that human cytochrome P-450 PCN1 (hPCN1, Mr approximately 52,000) was expressed in each of 40 individual specimens examined. In about 10-20% of the livers, an immunologically related protein having a lower electrophoretic mobility (Mr approximately 52,500) was also detected. A single liver was found that expressed only the lower mobility protein, designated hPCN3, and RNA isolated from this liver was used to construct a lambda gt11 library.

[Graft versus host reaction in an infant with DiGeorge syndrome].

An infant with complete DiGeorge syndrome was treated with blood transfusions and fresh frozen plasma because of severe septicemia and anemia. 9 weeks after the first transfusion and 2 weeks after administration of fresh frozen plasma he died of acute graft-versus-host disease. The blood products were routinely irradiated with 25 gray, the fresh frozen plasma was not irradiated.

Evidence for two closely related isozymes of arylamine N-acetyltransferase in human liver.

Acetyl CoA-dependent arylamine N-acetyltransferase (EC 2.3.1.

Prostaglandin-E2 9-ketoreductase from swine kidney. Production of antisera and application to development of a radioimmunoassay.

Prostaglandin-E2 9-ketoreductase (PGE2-9-KR, EC 1.1.1.

In vitro characterization of the human cytochrome P-450 involved in polymorphic oxidation of propafenone.

Propafenone is a new class 1 antiarrhythmic agent. The drug is extensively metabolized. 5-Hydroxylation and N-dealkylation constitute major metabolic pathways.

Anticancer drugs as inhibitors of two polymorphic cytochrome P450 enzymes, debrisoquin and mephenytoin hydroxylase, in human liver microsomes.

To identify potential substrates for the debrisoquin and mephenytoin hydroxylation polymorphisms, we performed in vitro inhibition studies with human liver microsomes and the respective prototype substrates in the absence and presence of several anticancer drugs. (+)-Bufuralol 1'-hydroxylation (as the prototype reaction for the debrisoquin polymorphism) was tested at 5 microM substrate concentration and in the presence of cyclophosphamide (0 to 200 microM), teniposide (0 to 100 microM), vinblastine (0 to 220 microM), etoposide (0 to 200 microM), flavone acetic acid (0 to 1000 microM), or ifosphamide (0 to 200 microM). (S)-Mephenytoin 4-hydroxylation was tested at 60 microM substrate concentration and in the presence of the same drugs as above; vincristine was also tested at 0 to 200 microM.

Antibodies against human cytochrome P-450db1 in autoimmune hepatitis type II.

In a subgroup of children with chronic active hepatitis, circulating autoantibodies occur that bind to liver and kidney endoplasmic reticulum (anti-liver/kidney microsome antibody type I or anti-LKM1). Anti-LKM1 titers follow the severity of the disease and the presence of these antibodies serves as a diagnostic marker for this autoimmune hepatitis type II. We demonstrate that anti-LKM1 IgGs specifically inhibit the hydroxylation of bufuralol in human liver microsomes.

Xenobiotic and endobiotic inhibitors of cytochrome P-450dbl function, the target of the debrisoquine/sparteine type polymorphism.

Five to 10% of Caucasians are poor metabolizers (PM) of debrisoquine, sparteine, bufuralol and numerous other drugs. A deficiency in cytochrome P-450dbl (P-450dbl) function is the cause of this polymorphism of drug oxidation with autosomal recessive inheritance. In the present study, inhibition of bufuralol-1'-hydroxylase in human liver microsomes by drugs and chemicals was performed in a search for potential new substrates for this polymorphic enzyme.

Absence of hepatic cytochrome P450bufI causes genetically deficient debrisoquine oxidation in man.

The common genetic deficiency of drug oxidation known as debrisoquine/sparteine-type polymorphism was investigated with bufuralol as prototype substrate. In human liver microsomes the 1'-hydroxylation of bufuralol is catalyzed by two functionally distinct P-450 isozymes, the high-affinity/highly stereoselective P450bufI and the low-affinity/nonstereoselective P450bufII. We demonstrate that P450bufI is unique in hydroxylating bufuralol in a cumene hydroperoxide (CuOOH) mediated reaction whereas P450bufII is active only in the classical NADPH- and O2-supported monooxygenation.

Two mutant alleles of the human cytochrome P-450db1 gene (P450C2D1) associated with genetically deficient metabolism of debrisoquine and other drugs.

The "debrisoquine polymorphism" is a clinically important genetic defect of drug metabolism affecting 5-10% of individuals in Caucasian populations. It is inherited as an autosomal recessive trait. A full-length cDNA for human cytochrome P-450db1, the deficient enzyme (also designated P450IID1 for P450 family II subfamily D isozyme 1), has recently been cloned.

Cyclosporine metabolism in human liver: identification of a cytochrome P-450III gene family as the major cyclosporine-metabolizing enzyme explains interactions of cyclosporine with other drugs.

The rate of formation of the three initial metabolites of cyclosporine metabolism has been determined in liver microsomes of 15 kidney transplant donors. Interindividual variation in metabolite formation was considerable but all three metabolites varied in parallel. An antiserum raised against a steroid-inducible rat cytochrome P-450 (P-450 PCN) strongly inhibited the formation of these metabolites.

Nutritional copper intoxication in three German infants with severe liver cell damage (features of Indian childhood cirrhosis).

Three of the four children of two unrelated German families fell ill in the first year of life with severe hepatopathy leading to death in two of the children so far, after a progressive clinical course and severe hepatic failure. Laboratory and morphological investigations revealed a high concentration of copper in the liver and to a lesser degree in the kidneys and other organs. The liver architecture was severely altered by micronodular cirrhosis with toxic liver cell damage similar to that found in Indian childhood cirrhosis.