Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.16.2 (PCP)
 3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mouse model of P-450 phencyclidine 3-cyclohydroxylase (P-450 PCP 3-cyclohydroxylase) genetic polymorphism is described. Up to a 3-fold difference was observed in the constitutive liver microsomal activity of P-450 PCP 3-cyclohydroxylase between "slow" (A/J and DBA/2J) and "rapid" (C57BL/6J and BALB/CJ) phencyclidine (PCP) metabolizers. The segregation of slow and rapid hydroxylator phenotypes between 17 recombinant inbred mouse strains derived from A/J and C57BL/2J mice suggests control of the activity by a single gene located on the X-chromosome or, less likely, on chromosome 17. A liver deficiency of P-450 PCP 3-cyclohydroxylase was observed in the New Zealand rabbit and Wistar rat, as well as in some human subjects. Any relationship of P-450 PCP 3-cyclohydroxylase polymorphism to other well characterized P-450 polymorphisms in mice (aryl hydrocarbon hydroxylase and coumarin hydroxylase) was excluded on the basis of differences in inducibility and activity distribution among the inbred mouse strains. Lack of relationship to the P-450 debrisoquine hydroxylase was confirmed by direct comparison of both activities in the same mouse and human liver microsomes. The pharmacological consequence of the observed polymorphism in mice appears to be that the rapid PCP metabolizers are more resistant to the effects of PCP compared to the slow metabolizers as based upon its ED50 and duration of action in A/J and C57BL/6J mice. The relevance of this data to humans remains to be determined, but clearly the latter show marked differences in PCP 3-cyclohydroxylase activity, which separate into low, intermediate, and high groups.
 ...
PMID:Genetic polymorphism of cytochrome P-450-dependent phencyclidine hydroxylation in mice. Comparison of phencyclidine hydroxylation in humans. 167 21

Pentachlorophenol-4-monooxygenase is an aromatic flavoprotein monooxygenase which hydroxylates pentachlorophenol and a wide range of polyhalogenated phenols at their para position. The PCP-degrading Sphingomonas species UG30 was recently shown to mineralize p-nitrophenol. In this study, the UG30 pcpB gene encoding the pentachlorophenol-4-monooxygenase gene was cloned for use to study its potential role in p-nitrophenol degradation. The UG30 pcpB gene consists of 1614 bp with a predicted translational product of 538 amino acids and a molecular mass of 59,933 Da. The primary sequence of pentachlorophenol-4-monooxygenase contained a highly conserved FAD binding site at its N-terminus associated with a beta alpha beta fold. UG30 has been shown previously to convert p-nitrophenol to 4-nitrocatechol. We observed that pentachlorophenol-4-monooxygenase catalyzed the hydroxylation of 4-nitrocatechol to 1,2,4-benzenetriol. About 31.2% of the nitro substituent of 4-nitrocatechol (initial concentration of 200 microM) was cleaved to yield nitrite over 2 h, indicating that the enzyme may be involved in the second step of p-nitrophenol degradation. The enzyme also hydroxylated p-nitrophenol at the para position, but only to a very slight extent. Our results confirm that pentachlorophenol-4-monooxygenase is not the primary enzyme in the initial step of p-nitrophenol metabolism by UG30.
 ...
PMID:The role of the Sphingomonas species UG30 pentachlorophenol-4-monooxygenase in p-nitrophenol degradation. 1022 Sep 2

Cocaine-mediated hepatotoxicity (CMH) requires cocaine (CCN) bioactivation by microsomal monooxygenase enzymes that results in cell death. Proposed mechanisms of toxicity involve reactive metabolites that covalently bind to hepatocellular proteins, depletion of cellular reducing equivalents through redox cycling, and/or the generation of reactive oxygen and nitrogen species that alter lipids and proteins. We have previously shown that phencyclidine (PCP) pretreatment potentiated CMH in CF-1 mice without increasing in vitro N-demethylation or N-hydroxylation of CCN. We have now further characterized PCP-potentiated CMH and determined that it is a dose- and time-dependent process, with PCP doses as low as 2.5 mg/kg for 3 days significantly increasing CMH. Immunohistochemistry and histology of livers from mice pretreated with PCP before CCN administration revealed a marked correlation between the regions of CCN metabolite binding and that of necrosis, whereas there was little binding or necrosis in vehicle-pretreated mice. Although hepatic GSH levels were not altered after repetitive PCP treatment alone, a sustained decrease (at least 6 h) in these levels was observed following CCN administration. Inhibitors of inducible nitric oxide synthase (NOS) abrogated PCP-potentiated CMH, although repetitive PCP treatment alone did not increase nitric oxide synthesis systemically or locally in hepatic tissue nor did lipopolysaccharide induction of NOS (without PCP) directly potentiate CMH. The precise mechanisms of PCP potentiation of CMH and involvement of NOS in CMH remain unclear, however, sustained depletion of GSH levels and increased hepatocellular binding of reactive cocaine metabolites have been demonstrated.
 ...
PMID:The effects of phencyclidine pretreatment on cocaine-mediated hepatotoxicity in mice. 1131 47

Toxicology studies of pentachlorophenol, a biocide used primarily as a wood preservative, were conducted by feeding diets containing a technical-grade composite, Dowicide EC-7 (a technical grade formulation), or pure pentachlorophenol to groups of B6C3F1 mice for 30 days. These three grades plus another commercial grade of pentachlorophenol (DP-2) were used in 6-month studies. These studies were followed by 2-year carcinogenicity studies of technical-grade pentachlorophenol and of Dowicide EC-7 in feed. Genetic toxicology studies were conducted in Salmonella typhimurium and in Chinese hamster ovary (CHO) cells. Thirty-Day and Sixteen-Month Studies: Groups of 19 male mice and 5-15 female mice were fed diets containing 0, 20, 100, 500, 2,500, or 12,500 ppm technical-grade pentachlorophenol, Dowicide EC-7, or pure pentachlorophenol for 30 consecutive days. Necropsies and histopathologic examinations were performed on all animals. Selected organs were weighed. Supplemental analyses included hematology, serum chemistry, urinalysis, immunology, and hepatic enzyme induction. Compound-related deaths were observed at the highest dose (12,500 ppm) with all three materials and at 2,500 ppm with EC-7 and pure pentachlorophenol (males only). Decreases in body weight gain were also observed in the groups in which deaths occurred. Diffuse centrilobular cytomegaly, karyomegaly, nuclear atypia, degeneration, or necrosis of the liver were compound-related lesions observed in all groups that received pure pentachlorophenol, technical-grade pentachlorophenol, or EC-7 at 500 ppm and above. Serum enzymes associated with liver injury were increased. In the 6-month studies, groups of 10 male and 10 female mice were given diets containing the various grades of pentachlorophenol at the following dietary concentrations: 200, 600, or 1,800 ppm technical-grade pentachlorophenol; 200, 600, or 1,200 ppm DP-2 (not used in the 30-day studies); 200, 600, or 1,200 ppm EC-7; or 200, 500, or 1,500 ppm pure pentachlorophenol for 26-27 weeks. Common control groups of 10 male and 10 female mice were fed control diets. Additional groups of male mice were examined for behavioral, histopathologic, clinical pathology, biochemical, and immunologic effects. All mice exposed at the highest dose of technical-grade pentachlorophenol died, as did 2/10 male mice exposed at the highest dose of DP-2. No deaths were observed in mice exposed to EC-7 or pure pentachlorophenol. Markedly lower final body weights were observed in the high dose groups only (all grades of pentachlorophenol). No chemical-relatedclinical signs were observed at sublethal doses. No major behavioral changes were observed after 5 weeks' exposure, but increased motor activity and heightened startle responses were present at the end of the study in female mice exposed to all four grades of pentachlorophenol. All grades of pentachlorophenol caused increases in serum enzymes associated with liver injury. All grades of pentachlorophenol also resulted in a dose-related induction of aryl hydrocarbon hydroxylase and an increase in cytochrome P450. However, the technical grade was a more powerful inducer than the other grades of pentachlorophenol. Pure pentachlorophenol had no effect on humoral or cell-mediated immunity. However, DP-2 and particularly technical-grade pentachlorophenol depressed humoral immune function. A dose-related increase in liver weight was observed in mice exposed to all grades of pentachlorophenol. A dose-related increase in spleen weight was observed in male mice exposed to all grades of pentachlorophenol; a decrease in spleen weight was observed in female mice exposed to all grades of pentachlorophenol except pure. After 6 months' exposure, histopathologic examination consistently revealed effects in the liver and urinary bladder. The liver lesions were present at all doses with all four grades of pentachlorophenol but were less severe at comparable doses in the mice exposed to pure pentachlorophenol; they consisted of hepatocellular karyomegaly, cytomegaly, and degeneration. The changes in the urinary bladder consisted of a brown granular pigment in the cells of the surface epithelium. No inflammation or proliferative response was associated with the pigment. Based primarily on the liver lesions observed in the 6-month studies, diets chosen for the 2-year studies contained 0, 100, or 200 ppm technical-grade pentachlorophenol or 0, 100, 200, or 600 ppm EC-7, fed to groups of 50 male and 50 female mice. DP-2 and pure pentachlorophenol were not chosen for the 2-year studies because of economic considerations and because the clinicopathologic syndrome observed in the 6-month studies was similar to that observed with EC-7. Body Weights and Survival in the Two-Year Studies: Mean body weights of mice exposed to technical-grade pentachlorophenol and EC-7 were comparable to those of controls until weeks 36-82. Thereafter, a 4%-22% dose-related decrease was observed in the mid and high dose mice exposed to EC-7 and in high dose mice exposed totechnical-grade pentachlorophenol. Females were more affected than males. Feed consumption by exposed mice was similar to that by controls. The average daily doses of technical-grade pentachlorophenol were approximately 17-18 or 35 mg/kg compared with 17-18, 34-37, or 114-118 mg/kg of EC-7. Survival of mice did not appear to be affected by exposure to either technical-grade pentachlorophenol or EC-7 at the doses used in these studies. Neoplastic and Nonneoplastic Effects in the Two-Year Studies: The incidences of hepatocellular adenomas and carcinomas were increased (dose related) in male and female mice exposed to either technical-grade pentachlorophenol or EC-7, although the increase was less marked in females exposed to technical-grade pentachlorophenol (adenomas or carcinomas, combined: technical-grade: male-- control, 7/32, 22%; low dose, 26/47, 55%; high dose, 37/48, 77%; female--3/33, 9%; 9/49, 18%; 9/50, 18%; EC-7: male--control, 6/35, 17%; low dose, 19/48, 40%; mid dose, 21/48, 44%; high dose, 34/49, 69%; female-- 1/34, 3%; 4/50, 8%; 6/49, 12%; 31/48, 65%). The incidences of pheochromocytomas in male mice were significantly greater than those in controls for both technical-grade pentachlorophenol (0/31; 10/45, 22%; 23/45, 51%) and EC-7 (1/34, 3%; 4/48, 8%; 21/48, 44%; 45/49, 92%). These neoplasms were also increased in female mice exposed to EC-7 at the highest dose (0/35; 2/49, 4%; 2/46, 4%; 38/49, 78%) but not in those exposed to technical-grade pentachlorophenol (2/33, 6%; 2/48, 4%; 1/49, 2%). Hyperplasia of the adrenal medulla was observed at increased incidences in mice that received either technical-grade pentachlorophenol (male: 1/31; 10/45; female: 0/33; 4/48; 2/49) or EC-7 (male: 1/34; 19/48; 13/48; 1/49; female: 2/35; 1/49; 5/46; 17/49). The incidences of hemangiosarcomas in the spleen and/or liver were significantly greater than those in controls for high dose female mice that received technical-grade pentachlorophenol (0/35; 3/50, 6%; 6/50, 12%) or EC-7 (0/35; 1/50, 2%; 3/50, 6%; 8/49, 16%). Compound-related nonneoplastic lesions occurred in the liver, spleen, and nose in mice exposed to either technical-grade pentachlorophenol or EC-7. The lesions in the liver included dose-related increased incidences of clear cell foci, chronic active inflammation, pigmentation, necrosis, cytomegaly, proliferation of hematopoietic cells, and bile duct hyperplasia. Increased amounts of extramedullary hematopoiesis of the splenic red pulp were observed at increased incidences in dosed male and high dose female mice that received technical-grade pentachlorophenol (male: 5/30; 15/23; 18/46; female: 2/33; 4/13; 11/47). Acutefocal inflammation of the nasal mucosa and focal metaplasia of the olfactory epithelium were observed at increased incidences in high dose mice that received EC-7 (inflammation--male: 4/35; 1/13; 3/16; 47/49; female: 0/35; 0/14; 2/5; 46/48; focal metaplasia-- male: 2/35; 1/13; 2/16; 46/49; female: 1/35; 0/14; 2/5; 45/48) but not in mice exposed to technical-grade pentachlorophenol. Genetic Toxicology: Pentachlorophenol (91.6% pure; equivalent in purity to the technical-grade pentachlorophenol used in the toxicology studies) was not mutagenic in S. typhimurium strains TA98, TA100, TA1535, or TA1537 when tested in the presence or absence of exogenous metabolic activation (S9). In cytogenetic studies with cultured CHO cells, pentachlorophenol produced an increase in chromosomal aberrations in the presence but not the absence of S9 metabolic activation; conversely, sister chromatid exchanges (SCEs) were induced only in the absence of S9. Audit: The data, documents, and pathology materials from the 2-year studies of pentachlorophenol have been audited. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenic activity for male B6C3F1 mice fed diets containing technical-grade pentachlorophenol, as shown by increased incidences of adrenal medullary and hepatocellular neoplasms. There was some evidence of carcinogenic activity for female B6C3F1 mice exposed to technical-grade pentachlorophenol, as shown by increased incidences of hemangiosarcomas and hepatocellular neoplasms. There was clear evidence of carcinogenic activity for male B6C3F1 mice exposed to pentachlorophenol, EC-7, as shown by increased incidences of adrenal medullary and hepatocellular neoplasms. There was clear evidence of carcinogenic activity for female B6C3F1 mice exposed to pentachlorophenol, EC-7, as shown by increased incidences of adrenal medullary and hepatocellular neoplasms and hemangiosarcomas. Chemically related increased incidences of nonneoplastic lesions in mice of each sex included hepatocellular cytomegaly, necrosis, inflammation, pigmentation, and clear cell foci and intrahepatic bile duct hyperplasia. Synonyms or Common Names: chlorophen; PCP; penchlorol; penta; pentachlorofenol; pentachlorofenolo; pentachlorphenol; 2,3,4,5,6-pentachlorophenol Trade Names: Acutox; Chem-Penta; Chem-Tol; Cryptogil ol; Dowicide 7; Dowicide EC-7; Dow Pentachlorophenol DP-2 Antimicrobial; Durotox; EP 30; Fungifen; Fungol; Glazd Penta; Grundier Arbezol; Lauxtol; Lauxtol A; Liroprem; Moosuran; Pentacon; Penta-Kil; Pentasol; Penwar; Peratox; Permacide; Permagard; Permasan;Permatox; Priltox; Permite; Santophen; Santophen 20; Sinituho; Term-i-Trol; Thompson's Wood Fix; Weedone; Witophen P
 ...
PMID:NTP Toxicology and Carcinogenesis Studies of Two Pentachlorophenol Technical-Grade Mixtures (CAS No. 87-86-5) in B6C3F1 Mice (Feed Studies). 1270 35