Molecular characterization of zeta class glutathione S-transferases from Pinus brutia Ten

Glutathione transferases (GSTs; EC 2.5.1.18) play important roles in stress tolerance and metabolic detoxification in plants.In higher plants, studies on GSTs have focussed largely on agricultural plants. There is restricted information about molecular characterization of GSTs in gymnosperms. To date, only tau class GST enzymes have been characterized from some pinus species. For the first time, the present study reports cloning and molecular characterization of two zeta class GST genes, namely PbGSTZ1 and PbGSTZ2 from Pinus brutia Ten., which is an economically important pine native to the eastern Mediterranean region and have to cope with several environmental stress conditions. The PbGSTZ1 gene was isolated from cDNA, whereas PbGSTZ2 was isolated from genomic DNA. Sequence analysis of PbGSTZ1 and PbGSTZ2 revealed the presence of an open reading frame of 226 amino acids with typical consensus sequences of the zeta class plant GSTs. Protein and secondary structure prediction analysis of two zeta class PbGSTZs have shared common features of other plant zeta class GSTs. Genomic clone, PbGSTZ2 gene, is unexpectedly intronless. Extensive sequence analysis of PbGSTZ2, with cDNA clone, PbGSTZ1, revealed 87% identity at nucleotide and 81% identity at amino acid levels with 41 amino acids differences suggesting that genomic PbGSTZ2 gene might be an allelic or a paralogue version of PbGSTZ1.

Integral Forensic Anthropology

Forensic anthropology is a new discipline with a long history of development and accomplishment. It traces its origin to the 19th century and includes many of the diverse areas of anthropology. However, its present growth is usually attributed to the effort of Ellis R. Kerley, of the University of Maryland. Kerley has been responsible for establishing the field as an intregral part of the forensic sciences. He also established it as a section of physical anthropology within the American Academy of Forensic Sciences. Since its inception in 1971, membership in the Academy has increased from 14 to about 50 people.

GST isoenzymes in matched normal and neoplastic breast tissue

The potential to metabolize endogenous and exogenous substances may influence breast cancer development and tumor growth. Therefore we investigated GST activity and the protein expression of glutathione S-transferases (GSTs) isoenzymes known to be involved in the metabolism of endogenous and exogenous carcinogens in breast cancer tissue to obtain new information on their possible role in tumor progression. The interindividual variation in the conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and of 1,2-epoxy-3-(p-nitrophenoxy) propane (EPNP) with glutathione (GSH) by cytosolic glutathione S-transferases (GSTs) were investigated in human breast matched normal and tumor samples. The GSTA, GSTM, GSTP and GSTT isoenzymes from the crude extracts of matched breast normal and tumor tissues in terms of their immunological properties using western blotting were compared. In most of the samples, the GST activities were higher in the tumor than in the normal cytosolic fractions against both CDNB and EPNP. In the western blotting analysis, it was proved statistically that in normal and tumor epithelial cells, there was difference between GST pi and theta isoenzymes expressions (p0.05). In normal epithelium there was a stronger GST theta expression than in invasive tumor tissues (p=0.013). However, the stronger GST pi expression was observed in tumor epithelium than in normal epithelium in human breast cancers (p=0.000). We found the GSTP protein level and GST activities were higher in the breast tumor than in the normal cytosolic fractions against both CDNB and EPNP, thus implicating a certain biological importance.

CYP and GST polymorphisms and survival in advanced non-small cell lung cancer patients

Several polymorphisms in cytochrome P-450s (CYP)s and Glutathione S-transferases (GST)s have been reported to be associated with survival rates of patients with non-small cell lung cancer (NSCLC) but the studies in this regard are scarce and the results are contradictory. In this study, CYP1A1 (Ile462Val), CYP1B1(Asn453Ser), GST M1, GSTP1 exon 5 (Ile105Val) and exon 6(Ala114Val) and GSTT1 polymorphisms were determined in 138 patients with advanced NSCLC to evaluate their role in survival. Of the studied CYP and GST polymorphisms only GSTP1 exon 6 variant significantly altered (improved) the survival compared to wild type (p=0.036) with median survival of 22.2 months and 16.1 months, respectively. Multivariate analysis also revealed a significant reduction of adjusted hazard ratio of death associated only with the GSTP1 exon 6 variant genotype of 0.45 (95% confidence interval (95% CI), 0.23-0.89, p=0.022). These results show that the GSTP1 exon 6 variant genotype is associated with improved survival in the patients with advanced NSCLC.

KEYWORDS

Cytochrome P-450, glutathione S-transferase, non small cell lung cancer, polymorphism, survival.

A study on the antioxidant activities of some new benzazole derivatives

The in vitro antioxidant properties of some new benzazole derivatives (1-10) such as benzoxazoles, benzimidazoles, and benzothiazoles were determined by their effects on the rat liver microsomal NADPH-dependent lipid peroxidation (LP) level, the scavenging of superoxide anion and the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Compounds 1, 2, 4 and 6, showed potent scavenging effect on superoxide radical at 10(-3) M. Compound 8, 5-nitro-2-(phenoxymethyl)benzimidazole, strongly inhibited lipid peroxidation at 10(-3) M concentration.

Comparison of NAT1, NAT2 and GSTT2-2 activities in normal and neoplastic human breast tissues

In this study, arylamine N-acetyltransferases, NATs (E.C.2.3.1.5) and glutathione-S-transferase-T2-2, GSTT2-2 (E.C.2.5.1.18) enzyme activities in the breast tumor and surrounding tumor-free tissues of 22 female breast cancer patients with infiltrating ductal carcinoma were measured. The possible impacts of grade of malignancy, chemotherapy treatment, estrogen receptor status and menopausal status on all enzyme activities were evaluated. The results showed that, both NAT2 and GSTT2-2 display significant differences between tumor and tumor-free breast tissues, while no difference was observed in NAT1. Grade of malignancy seems to be positively associated with NAT1 and negatively associated with GSTT2-2. Though, both NAT2 and GSTT2-2 have increased mean tumor activities, the grade of malignancy, chemotherapy status, menopausal status or estrogen receptor status are not correlated statistically.

Genotoxicity studies on benzimidazole retinoids

Retinoids consist of a family of naturally occuring compounds including all-trans retinoic acid (ATRA), retinal, retinol (vitamin A), 9-cis retinoic acid, 13-cis retinoic acid as well as a large number of synthetic derivatives. Retinoids are known to elicit diverse pharmacological profiles such as controlling cell differentiation/proliferation and modulating specific premalignant lesions and reducing second primary tumors in patients. Clinical use of retinoids is limited due to their toxicity. Three benzimidazole retinoid derivatives (BITN, BITNm, BITNe) were synthesized and were examined in terms of genotoxicity towards human lymphocyte cultures by sister chromatid exchange (SCE) analysis. It has been found that BITN decreased the number of SCEs 20% at 10(-6) M, but had no effect at 10(-5) M. No significant effect on SCEs was observed for BITNm and BITNe at both concentrations. ATRA increased the SCEs (35%) at 10(-5) M but had no effect at 10(-6) M. The results have shown that benzimidazole retinoids did not induce SCE significantly. Besides this, BITN reduced the SCEs and had a protective effect at low concentration. Since the induction of glutathione S-transferase (GST) is associated with anticancer drug resistance, the effects of BITN, BITNm, BITNe and ATRA on human lymphocyte GSTs were also investigated using CDNB as substrate. BITN and BITNm induced GST activities 54% and 49% respectively at 10(-5) M, but had no effect at 10(-6) M. BITNe induced GST activity 62% at 10(-5) M and 35% at 10(-6) M. ATRA had no effect on GST activity at 10(-5) M.

Acute effect of nebulized budesonide in asthmatic children

The acute anti-inflammatory effects of inhaled steroids at high doses and their use at home and as emergency treatment of acute asthma attacks in children have been evaluated in many clinical studies. However very little is known about their additional bronchodilator response to systemic steroids plus nebulized salbutamol in the early management in children. Asthmatic patients aged between 5-15 years were investigated in a double-blind, placebo-controlled fashion. Both the study group (Group I) and the control group (Group II) received three consecutive doses of nebulized salbutamol (0.15 mg/kg/dose) and one dose of parenteral methylprednisolone (1 mg/kg/dose, intramuscularly). After this treatment, nebulized budesonide (1 mg/dose) was administered to patients in the study group and placebo (nebulized saline) was administered to patients in the control group. Pulmonary index scoring and peak flow meter was performed to both groups before and after the treatment. There were twelve patients in Group I (mean age: 7.90 +/- 2.34 years) and fourteen patients in Group II (mean age: 9.36 +/- 2.55 years). There was no difference between the two groups with respect to age (p = 0.1421), gender (p = 1.000) and inhaled steroid prophylaxis rate (p = 0.2177). No statistically significant difference was detected between the two groups with respect to the pulmonary index score (p = 0.3528). Yet, there was a statistically significant difference between the two groups with respect to the increase in PEFR (p = 0.0155). The positive acute effect of nebulized budesonide in addition to systemic steroids and nebulized salbutamol in improving the spirometric indices in asthmatic children is an encouraging finding for further investigations of its routine use in the pediatric emergency department.

Synthesis and antioxidative properties of novel thiazolidinedione/imidazolidinedione compounds as retinoids

The general term "retinoids" refers to both naturally occurring as well as synthetic compounds which exhibit biological activity similar to vitamin A (retinol). Vitamin A and its two metabolites, retinaldehyde and retinoic acid, are fat-soluble unsaturated isoprenoids necessary for the growth, differentiation and maintenance of epithelial tissues. In this study, we have synthesized thiazolidinedione/imidazolidinedione compounds as retinoids. Their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels and superoxide anion formation were determined.

The expression of cytochrome P450 enzymes in human breast tumours and normal breast tissue

Environmental chemicals are one of the risk factors in breast cancer genesis. Cytochrome P450 (CYP) enzymes play a major role in the activation of these chemicals. Using highly specific and sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. the expression profile of all major xenobiotic metabolizing CYP forms was screened in breast tumour and surrounding tumour free (control) breast tissue in a series of 20 sample pairs obtained from females with infiltrating ductal carcinoma. The levels of CYPIAI mRNA were very low in both tumour and normal tissue. CYP1B1, CYP2B6, CYP2C, CYP2D6, CYP2E1, CYP4B1, and CYP11A1 expressions were positive in both tumours and control tissue. CYP2A6, CYP2A7, CYP2A13, CYP2F1, CYP3A4, CYP3A5. and CYP3A7 mRNAs were expressed neither in tumours nor in control tissue. These results show that several CYPs. responsible for the activation of a quite large number of procarcinogens and genotoxic estrogen metabolites. are expressed in breast tissue with a lack of qualitative differences in CYP expression at mRNA level between breast tumours and surrounding normal breast.

Xenobiotic metabolizing and antioxidant enzymes in normal and neoplastic human breast tissue

An investigation was made of ethoxyresorufin O-deethylase (EROD) activity, a cytochrome P450 (CYP) dependent enzyme mainly catalyzed by CYP1A1, glutathione S-transferase (GST) activity toward the substrates 1-chloro-2,4- dinitrobenzene (CDNB) and ethacrynic acid (EAA), reduced glutathione (GSH) levels, and antioxidant enzyme (AOE) activity namely catalase (CAT) and selenium- dependent glutathione peroxidase (Se-GPx) in tumor and surrounding tumor-free (normal) tissues in female breast cancer patients. Wide interindividual variations were found in the enzyme activities in both tumor and normal breast tissues. No significant differences were noted between mean EROD and CAT activities in tumor and normal breast tissues. The mean activities of CDNB GST, EAA GST and Se-GPx and GSH levels in tumor tissue were significantly higher than those in normal breast tissue. These results show that CYP, GST and AOE behave differentially in breast tumors.

Glutathione and lipid peroxidation levels in human breast tumors

The levels of reduced glutathione (GSH) and lipid peroxidation (LP) of breast tumor and surrounding tumor free (normal) tissues of 39 breast cancer female patients with infiltrating ductal carcinoma and the relationship between these two parameters were investigated. Large interindividual variations in the levels of GSH and LP were found in both tumor and normal tissues. The mean GSH levels of tumors were significantly higher than those of normal tissues. This tendency did not change with the stage and grade (excluding grade 1) of the malignancy, menopausal status and chemotherapy treatment. No correlation was found between GSH level and stage or grade of malignancy (p > 0.05). However, although more than half of the tumor samples (23/39, 59%) had higher LP levels than their corresponding normal tissues, no significant difference was noted between the mean LP levels of tumor and normal tissues. This tendency did not change with the stage and grade of the malignancy, and menopausal status and chemotherapy treatment. No relationship was observed between the LP level and stage or grade of malignancy (p > 0.05). Overall, no association existed between the levels of GSH and LP in tumors (p > 0.05). These results reveal that the GSH, but not LP, could be a marker of breast malignancy and that the increase in GSH level is not sufficient to lower the LP level in human breast tumors.

A study on the antioxidant capacities of some benzimidazoles in rat tissues

Seven benzimidazole compounds were synthesized and their in vitro effects on rat liver, lung and kidney microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. The significant decrease in male rat liver microsomal LP level was noted only by the compound 4 at 10(-4) M (20%) and 10(-3) M (40%) concentrations whereas the other compounds were ineffective. In lung, only the compound 6 at 10(-4) M concentration exhibited significant alteration, i.e. 56% increase, in LP level. In kidney, however, apart from the compound 4, all the compounds increased LP level (35-52%) significantly. The classical antioxidant, butylated hydroxy toluene (BHT), at 10(-4) M concentration, significantly decreased LP level about 70%, in all the tissues studied. To clarify the effects of compounds 4 and 6 on LP, the responses of some CYPs, which are active in producing reactive oxygen species, to these compounds were also investigated. The compound 4 at 10(-4) and 10(-3) M concentrations inhibited the hepatic microsomal ethoxyresorufin O-deethylase (EROD) (37 and 65%) and pentoxyresorufin O-depenthylase (PROD) (14 and 62%) enzyme activities significantly. However, it did not alter the hepatic microsomal NADPH-cytochrome P450-reductase activity. BHT, at 10(-3) M concentration, significantly inhibited hepatic microsomal EROD (73%), PROD (62%) and NADPH-cytochrome P450 reductase (17%) enzyme activities. Caffeine (10(-3)M) and SKF 525A (10(-3)M), which are specific inhibitors of EROD and PROD enzyme activities, significantly decreased the enzyme activities 33 and 77%, respectively. Caffeine was unable to alter hepatic microsomal NADPH-cytochrome P450 reductase enzyme activity whereas SKF 525A significantly inhibited (80%) it. In lung and kidney, the compound 6 at 10(-4)M concentration significantly increased EROD (44 and 19%) and PROD (103 and 86%) enzyme activities. However, the elevation of PROD enzyme activity in both tissues was observed to be more pronounced than that of EROD enzyme activity. This compound was ineffective on lung and kidney microsomal P450-reductase enzyme activity. These results reveal that the synthesized benzimidazoles have variable tissue dependent in vitro effects on LP due to their distinct effects on CYP activities but not on NADPH-cytochrome P450 reductase activity in rats.

Gender dependent effects of cigarette smoke on hepatic and pulmonary xenobiotic metabolizing enzymes in rats

The adult male and female rats were exposed to cigarette smoke (CS) 5 times a day, with 1 h intervals, for 3 days in a chamber where smoke and fresh air lead alternatively and were killed 16 h after the last treatments and hepatic and pulmonary monooxygenase (MO) activities (aniline-4-hydroxylase, AH; aminopyrine-N-demethylase, AMND; 7-ethoxyresorufin-O-deethylase, EROD; p-nitroanisole-O-demethylase, p-NAOD), lipid peroxidation (LP) and reduced glutathione (GSH) levels and glutathione-S-transferases (GSTs) activities toward several substrates (1-chloro-2,4-dinitrobenzene, CDNB; 1,2-dichloro-4-nitrobenzene, DCNB; ethacrynic acid, EAA; 1,2-epoxy-3-(p-nitrophenoxy)-propane, ENPP) were determined. CS significantly increased hepatic AMND, EROD and p-NAOD activities whereas it unaltered AH activity in both genders as compared with controls. In the lung, EROD and p-NAOD activities were also significantly increased by CS in both genders. Pulmonary AH activity, however, significantly increased in males but remained unchanged in females. Pulmonary AMND activity significantly increased in females but remained unaltered in males. A significant decrease was noted in the LP level of males, while that of females was unaltered by CS in the liver. Pulmonary GSH and LP, and hepatic GSH levels were significantly increased by CS in both genders. In males, GST activities toward CDNB and DCNB did not alter, whereas GST activities toward EAA and ENPP significantly increased and decreased, respectively, in the liver. In females, CS significantly increased hepatic GST activity toward DCNB but it was ineffective on the other hepatic GST activities. All pulmonary GST activities of males were significantly depressed by CS. In females, however, CS significantly increased pulmonary GST activities toward CDNB and DCNB but was ineffective on GST activities toward EAA and ENPP. These results suggest that gender related differences exist in the modulations of hepatic GST, and pulmonary MO and GST activities but not in those of hepatic MO activities, by CS in rats.

Effects of a benzimidazole compound on monooxygenase activities

A retinoid-type benzimidazole compound (benzimidazole-tetranaphthalene, BITN) was synthesized and its effects on hepatic cytochrome P450 (CYP) dependent ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-depentylase (PROD) enzyme activities were determined in rats in vitro. In vitro addition of BITN in 10(-3) M concentration to the reaction medium caused inhibitions in EROD (94%) and PROD (82%) activities. With the same concentration (10(-3) M) all-trans-retinoic acid (RA) was able to inhibit EROD activity 65% and PROD activity 59% whereas buthylated hydroxytoluen (BHT) inhibited EROD and PROD activities 73% and 62%, respectively. The specific inhibitors of EROD activity (caffeine) and PROD activity (SKF 525A) at 10(-3) M concentration inhibited the corresponding enzymes 33% and 77%, respectively. Thus, these results reveal that the BITN has a stronger inhibitory effect than RA, BHT, caffeine and SKF 525 A on the enzyme activities. Since these enzymes (EROD, CYP 1A1/2 and PROD, CYP2B1) activate polycyclic hydrocarbons, aromatic amines and aliphatic halogenated hydrocarbons to their ultimate mutagenic or carcinogenic forms, and are effective in producing reactive oxygen species such as superoxide, hydroxyl radical and hydrogen peroxide, the new compound, BITN, appears to have a greater anticarcinogenic and antioxidant potential than RA and BHT.

Differential responses of hepatic monooxygenases and glutathione S-transferases of mice to a combination of cadmium and nickel

The acute combined effects of cadmium (Cd) and nickel (Ni) on hepatic monooxygenase activities (ethylmorphine N-demethylase, EMND; aminopyrine N-demethylase, AMND; aniline 4-hydroxylase, AH), cytochrome P-450, cytochrome b5, microsomal heme and reduced glutathione (GSH) levels and glutathione S-transferase (GST) activities toward several substrates (1-chloro-2,4-dinitrobenzene, CDNB; 1,2-dichloro-4-nitrobenzene, DCNB; ethacrynic acid, EAA; 1,2-epoxy-3-(p-nitrophenoxy)-propane, ENPP) were determined and compared with those of Cd or Ni alone in mice. Male adult mice (25-30 g) were administered either a single dose of Cd (3.58 mg CdCl2.H2O/kg, i.p.) 48 hr prior to killing or a single dose of Ni (59.5 mg NiCl2.H2O/kg, s.c.) 16 hr prior to killing. For the combined treatment, the animals received the single dose of Ni 32 hr after the single dose of Cd and were then killed 16 hr later. Cd treatment alone significantly decreased EMND, AMND, and AH activities and cytochrome P-450 and heme levels as compared with controls. Cytochrome b5 level was not altered by Cd treatment. Cd also inhibited GSH level and the GST activities toward CDNB, EAA and ENPP significantly. No significant change was observed in the GST activity for DCNB by Cd. Ni treatment alone, however, decreased the monooxygenase and GST activities studied, and cytochrome P-450, cytochrome b5, heme and GSH levels significantly. Combined treatment significantly depressed the monooxygenase activities and cytochromes and heme levels. GSH level was not significantly altered.(ABSTRACT TRUNCATED AT 250 WORDS)

Interindividual variability of coumarin 7-hydroxylation in a Turkish population

One hundred healthy Turkish volunteers (70 male, 30 female) aged from 19 to 56 years were given 5 mg coumarin p.o. after an overnight fast. Urine samples were collected before and 2, 4 and 8 h after drug administration. The extent and rate of formation of 7-OH-coumarin (7OHC) was determined by the urinary excretion of the metabolite as measured with the fluorometric method. On average, 80% of 7OHC formed was excreted in 2 h. The total amount of 7OHC formed was 59.8% (21.5%) (mean and SD, n = 100, range 17-100%) of the given dose. The percentage of 7OHC excreted during the first 2 h compared with the 7OHC excretion at 8 h was a constant and stable individual characteristic for the rate of the formation of 7OHC ('2 h coumarin test'). Although four individuals had relatively slow coumarin test values (34-40%), no clear-cut polymorphism in the rate of 7OHC formation was found. However, 7OHC formation was lower in males and in cigarette smokers.

Differential combined effect of cadmium and nickel on hepatic and renal glutathione S-transferases of the guinea pig

When male guinea pigs were given a single dose of Cd (2.0 mg Cd2+/kg, ip) 72 hr prior to sacrifice, the hepatic reduced glutathione (GSH) level did not change although glutathione S-transferase (GST) activities toward the substrates 1-chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), ethacrynic acid (EAA), and 1,2-epoxy-3-(p-nitrophenoxy) propane (ENPP) increased significantly as compared to controls. Cd did not change the renal GSH level and GST activities toward CDNB and EAA. However, significant increase was observed in the GST activity for DCNB whereas GST activity for ENPP was significantly inhibited by Cd. When the animals were given a single dose of Ni (14.8 mg Ni2+/kg, sc) 16 hr prior to sacrifice, significant increases were observed in hepatic GSH level and GST activities toward CDNB, DCNB, EAA and ENPP. Ni, however, depressed the renal GSH level and GST activities toward CDNB, DCNB and ENPP significantly. The renal GST activity toward EAA remained unaltered. For the combined treatment, guinea pigs received the single dose of Ni 56 hr after the single dose of Cd and then they were killed 16 hr later. In these animals, no significant alteration was observed in the hepatic GSH level. The augmentation of elevation was observed in hepatic GST activities toward CDNB and DCNB. Combined metal treatment did not potentiate the elevation of hepatic GST activities toward EAA and ENPP to any greater degree. The depression of renal GSH level was significantly ameliorated by the combined treatment. Combination treatment potentiated the depression of renal GST activity for ENPP but not for CDNB.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerium-induced strain-dependent increase in Cyp2a-4/5 (cytochrome P4502a-4/5) expression in the liver and kidneys of inbred mice

The murine Cyp2a-4 and Cyp2a-5 genes encode P450 isoforms catalysing testosterone 15 alpha-hydroxylase and coumarin 7-hydroxylase (COH) activities, respectively. Two days after the administration of a hepatotoxic dose of cerium chloride (2 mg/kg i.v.), COH activity was increased 3.2-fold in the liver of DBA/2 mice. Three and 4 days after the cerium treatment, coinciding with the occurrence of overt liver damage, there was a dramatic decrease in COH activity. The activities of testosterone 15 alpha-hydroxylase and the Cyp1a-1-mediated 7-ethoxyresorufin O-deethylase (EROD) were decreased in response to cerium. Much less pronounced changes in the enzyme activities occurred in the C57BL/6 mouse liver. Northern blot analysis showed a 21-fold increase in the hepatic Cyp2a-4/5 mRNA in the DBA/2 mice at day 2, whereas no increase occurred in the C57BL/6 mice. Also in the kidneys the increase in COH activity and in Cyp2a-4/5 mRNA was marked only in the DBA/2 mice. A polymerase chain reaction-mediated analysis method utilizing a unique PstI restriction site in the Cyp2a-5 cDNA was used to differentiate between the highly homologous Cyp2a-4 and Cyp2a-5 mRNAs. Cerium was found to increase the amount of hepatic and renal Cyp2a-4 and Cyp2a-5 mRNA only in the DBA/2 mice. These data indicate that the Cyp2a-4/5 complex is regulated in a different way in DBA/2 and C57BL/6 mice and that some association exists between the development of liver damage and COH induction.

Endoscopic sphincterotomy in the management of postoperative complications of hepatic hydatid disease

The results obtained using endoscopic sphincterotomy (EST) in the management of postoperative biliary complications of hepatic hydatid disease are presented. The outcome was favourable in all eight patients treated with no associated morbidity or mortality. In three patients the clinical manifestations of cholangitis resolved, and in five of six patients the external bile fistula previously present for 26 to 68 days closed within 3 to 15 days. In one patient with a long-standing fistula (5 years) the bile outflow was reduced from 600cc to 50-100cc per day. No complications due to EST were encountered. The results show that EST can be considered the treatment of choice for biliary fistulae following surgery for hepatic hydatid disease and for drainage of bile in patients with cholangitis due to hydatid disease.

Distinct forms of cytochrome P-450 are responsible for 6 beta-hydroxylation of bile acids and of neutral steroids

Cytochrome P-450-dependent 6 beta-hydroxylation of bile acids in rat liver contributes to the synthesis of the quantitatively important pool of 6-hydroxylated bile acids, as well as to the detoxification of hydrophobic bile acids. The lithocholic acid 6 beta-hydroxylation reaction was investigated and compared with androstenedione 6 beta-hydroxylation. Differential responses of these two activities to inducers and inhibitors of microsomal P-450 enzymes, lack of mutual inhibition by the two substrates and differential inhibition by antibodies raised against several purified hepatic cytochromes P-450 were observed. From these results it was concluded that 6 beta-hydroxylation of lithocholic acid is catalysed by P-450 form(s) different from the subfamily IIIA cytochromes P-450 which are responsible for the bulk of microsomal androstenedione 6 beta-hydroxylation. Similar, but more tentative, results revealed that the 7 alpha-hydroxylation of lithocholic acid and of androstenedione may be also catalysed by distinct P-450 enzymes. The results indicate that cytochromes P-450 hydroxylating bile acids are distinct from analogous enzymes that carry out reactions of the same regio- and stereo-specificity on neutral steroids (steroid hormones). A comparison of pairs of cytochromes P-450 that catalyse the same reaction on closely related steroid molecules will help to define those structural elements in the proteins that determine the recognition of their respective substrates.

Human liver steroid sulphotransferase sulphates bile acids

The sulphation of bile acids is an important pathway for the detoxification and elimination of bile acids during cholestatic liver disease. A dehydroepiandrosterone (DHEA) sulphotransferase has been purified from male and female human liver cytosol using DEAE-Sepharose CL-6B and adenosine 3',5'-diphosphate-agarose affinity chromatography [Falany, Vazquez & Kalb (1989) Biochem. J. 260, 641-646]. Results in the present paper show that the DHEA sulphotransferase, purified to homogeneity, is also reactive towards bile acids, including lithocholic acid and 6-hydroxylated bile acids, as well as 3-hydroxylated short-chain bile acids. The highest activity towards bile acids was observed with lithocholic acid (54.3 +/- 3.6 nmol/min per mg of protein); of the substrates tested, the lowest activity was detected with hyodeoxycholic acid (4.2 +/- 0.01 nmol/min per mg of protein). The apparent Km values for the enzyme are 1.5 +/- 0.31 microM for lithocholic acid and 4.2 +/- 0.73 microM for taurolithocholic acid. Lithocholic acid also competitively inhibits DHEA sulphation by the purified sulphotransferase (Ki 1.4 microM). No evidence was found for the formation of bile acid sulphates by sulphotransferases different from the DHEA sulphotransferase during purification work. The above results suggest that a single steroid sulphotransferase with broad specificity encompassing neutral steroids and bile acids exists in human liver.

Regional and subcellular distribution of cytochrome P-450-dependent drug metabolism in monkey brain: the olfactory bulb and the mitochondrial fraction have high levels of activity

In brain of female monkey (M. fascicularis) the content of cytochrome P-450 and benzo(a)pyrene hydroxylase activity in the mitochondrial fraction exceeded that of the microsomes by more than 4-fold. The mitochondrial drug metabolism activity exhibited substrate specificity and, unlike the microsomes, did not catalyze 7-ethoxyresorufin O-deethylase reaction. Moreover, the rate of benzo(a)pyrene hydroxylase activity by both the mitochondrial and the microsomal fractions displayed regional variation with the olfactory bulb displaying the highest hydroxylase activity. In contrast, the microsomal 7-ethoxyresorufin O-deethylase activity was uniformally distributed in all brain regions.

cis-platinum-mediated decrease in serum testosterone is associated with depression of luteinizing hormone receptors and cytochrome P-450scc in rat testis

Previously we had shown that cis-platinum decreases testosterone levels in rat serum and that hCG reverses this effect. The purpose of these studies was to determine the biochemical basis of cis-platinum-mediated effects on testicular testosterone production. In the testis of rats treated with cis-platinum (7 mg/kg, iv), the mitochondrial P-450scc concentration and side-chain cleavage activity were depressed by 40%. Also, the microsomal 17 alpha-hydroxylase activity and cytochrome P-450 concentration were decreased. Testicular binding capacity (in vitro) for [125I]hCG was decreased by 75-80%. On the other hand, FSH binding to Sertoli cell membrane receptors was not appreciably changed. hCG (25 IU/100 g daily) in treated rats caused complete occupancy of the remaining 20-25% LH receptors and caused a 20- to 30-fold increase in serum and testicular testosterone, a 2-fold increase in mitochondrial P-450scc, and a 5-fold acceleration of side-chain cleavage activity. 17 alpha-Hydroxylase activity and microsomal cytochrome P-450 were not increased over the control values. In addition to testicular functions, pituitary glycoprotein hormone production was assessed. Treatment of rats with cis-platinum (7 mg/kg, iv) did not change serum LH or FSH, but caused a 50% decrease in serum and testicular testosterone levels. A GnRH challenge test (1.5 micrograms/100 g, in 30 min) of treated rats caused prompt increases of 10- to 15-fold in serum LH and resulted in increases in serum and testicular testosterone. Thus, there was little evidence for cis-platinum effects at the level of hypothalamus or pituitary that could account for the decreased testosterone production. Reversal of the cis-platinum effect on steroidogenesis by hCG or GnRH appears to be due to the induction of suprasaturating levels of LH with full occupancy of remaining Leydig cell LH receptors. This, in turn, would reverse the diminished levels of mitochondrial side-chain cleavage activity and cytochrome P-450scc. These data suggest that cis-platinum causes a depression in serum testosterone, mainly by decreasing the number of LH receptors and inhibiting side-chain cleavage activity.

Differential regulation of heme and drug metabolism in rat testis and prostate: response to cis-platinum and human chorionic gonadotropin

In the absence of notable changes in heme metabolic activities in the testes of rats treated with cis-platinum (7 mg/kg i.v.) and sacrificed after 1, 3 or 7 days, time-dependent decreases in the activity of benzo(a)pyrene hydroxylase (AHH), ethoxyresorufin O-deethylase (7-ERDE) and the concentration of cytochrome P-450 were observed. In contrast, in the prostate of the treated rats, despite reductions in the activity of heme oxygenase and that of enzymes of heme biosynthetic pathway, biotransformation of benzo(a)pyrene and ethoxyresorufin and cytochrome P-450 concentration were not altered. cis-Platinum treatment (7 days) also decreased markedly the serum and testicular testosterone levels (50-70%). Human chorionic gonadotropin (hCG, 25 IU/100 g/day for 7 days) given to the treated rats (7 days) caused a 5- to 15-fold increase in the serum and testicular testosterone levels and reversed the spectrum of the aforementioned inhibitory effects of cis-platinum on heme metabolic enzymes. The response of the testis and prostate drug metabolic activities to hCG treatment also differed. In the testis of cis-platinum-treated rats, the inhibited AHH and 7-ERDE activities were reversed by hCG treatment and cytochrome P-450 concentration returned to the control level. In the prostate, however, hCG treatment neither changed AHH and 7-ERDE activities nor the concentration of the microsomal cytochrome P-450. In addition, in the testis the pattern of response of AHH and 7-ERDE activities to hCG was dissimilar; whereas 7-ERDE activity returned to the normal level, AHH activity surpassed the normal activity and reached a near 2.5-fold increase over the control value.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzo[a]pyrene-DNA-adducts and monooxygenase activities in mice treated with benzo[a]pyrene, cigarette smoke or cigarette smoke condensate

Synchronous fluorescence spectrophotometry (SFS), developed to study benzo[a]pyrene-7,8-diol-9,10-epoxide(BPDE)-DNA, was used to measure the in vivo formation of DNA-adducts in genetically responsive C57BL/6 (B6) and non-responsive DBA/2 (D2) mice. Treatment with cigarette smoke by inhalation for 3-16 days, or i.p. injection of cigarette smoke condensate or neutral fraction did not lead to detectable levels of BPDE-DNA-adducts in either lungs or liver, although aryl hydrocarbon hydroxylase (AHH) activity, an indicator of benzo[a]pyrene (BP) metabolism, was clearly induced in lungs of B6 mouse. A dose-dependent amount of BPDE-DNA-adducts in lung and somewhat less in liver was found after i.p. injection with BP (20-80 mg/kg). Mice treated with vehicle or 4 mg/kg of BP were negative for adducts by SFS. In B6 mice AHH was induced both in lungs and livers while there was no AHH induction in D2 mice although the levels of BPDE-DNA-adducts were somewhat higher than in B6 mice. Thus, no clear correlation seems to exist between AHH activity and the formation of BPDE-DNA-adducts. Also, according to our results SFS can be used to quantitate adduct-formation in in vivo animal studies.

Effects of 2-arylbenzimidazoles on rat hepatic microsomal monooxygenase system

1. The effects of eight newly synthesized 2-aryl substituted benzimidazole derivatives on control and phenobarbital (PB) treated rat liver microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase activities, and their binding to control and PB-treated rat liver microsomal oxidized cytochrome P-450 are presented. 2. All compounds inhibited ethylmorphine N-demethylase activity with I50 values ranging from 8.50 x 10(-4) M to 27.83 x 10(-4) M in control and ranging from 2.80 x 10(-4) M to 15.79 x 10(-4) M in PB-treated rats. 3. Aniline 4-hydroxylase activity was inhibited by all of the compounds tested having I50 values in the range of 7.04 x 10(-4) M-31.37 x 10(-4) M in PB-treated rats, but only five of the compounds showed inhibitory activity in control rats. 4. Only a few significant regression coefficients could be found between the parameters of the chemicals studied and their inhibitory patterns. 5. No correlation has been observed between the binding of the derivatives and their inhibitory pattern.

Inhibition of human hepatic and placental xenobiotic monooxygenases by imidazole antimycotics

Three imidazole antimycotic drugs, ketoconazole, clotrimazole and miconazole, were studied to characterize the inhibition of aryl hydrocarbon hydroxylase (AHH), 7-ethoxycoumarin O-deethylase (ECDE) and 7-ethoxyresorufin O-deethylase (ERDE) activities in human liver and placenta in vitro in comparison with liver enzymes from control, phenobarbital (PB) and 3-methylcholanthrene (MC) pretreated rats. All three compounds inhibited rat liver enzymes, although MC pretreatment seemed to lead to a resistance of inhibition relative to PB-treated and control animals. There were large differences in the extent of inhibition of human hepatic and placental activities. Furthermore, while the type of inhibition of the hepatic ERDE was competitive or mixed, that of the placental enzyme cannot be described in ordinary terms of inhibition kinetics. Ketoconazole and clotrimazole were relatively potent inhibitors of maternal cigarette smoking-induced placental ECDE activities (IC50 values from 0.5 microM to 5 microM), whereas much less inhibition of the placental AHH activity was obtained with ketoconazole and miconazole (IC50 values from 50 microM to 500 microM). In most cases, hepatic enzymes were less sensitive to antimycotics than placental activities. This was in contrast with results from rat enzyme studies, in which MC pretreatment seemed to decrease the inhibitory response.