Monoclonal antibody-directed assessment of toluene induction of rat hepatic cytochrome P450 isozymes

Cytochrome P450 isozymes induced in rat liver by a range of concentrations of toluene were studied with monoclonal antibodies (MAbs) to specific P450 isozymes and by enzyme assays. Nitrosodimethylamine demethylase activity was significantly increased in microsomes from rats exposed to more than 1000 ppm of toluene, an increase that was dose-dependent. Anti-CYP2E1 significantly inhibited the metabolism of toluene to benzyl alcohol (BA) by about 50%, in microsomes from 1000 to 4000 ppm toluene-exposed rats, at low substrate concentration (0.2 mM). With anti-CYP2B1/2, the rate of BA formation was decreased by 15-17% in microsomes from rats of 2000 and 4000 ppm toluene exposures at high substrate concentration (5.0 mM). On the other hand, anti-CYP2C11/6 inhibited the rate of formation of BA in all of the microsomes, but the extent of inhibition was progressively decreased from 55% in control to 33% in 4000 ppm exposure. Immunoblot analysis with anti-CYP2E1 and anti-CYP2B1/2 revealed stronger immunoreactive bands in microsomes from rats exposed to more than 1000 and 2000 ppm of toluene, respectively. Stronger bands were also observed in microsomes from rats of 2000-4000 ppm toluene exposures with anti-CYP3A1/2, but no immunoreactivity appeared with anti-CYP1A1/2. These results suggest that toluene induces CYP2E1, CYP2B1/2 and CYP3A1/2, but reduces CYP2C11/6, and has no effect on CYP1A1/2.

Induction and inhibition of cytochrome P-450-dependent monooxygenases in hamster tissues by ethanol

The effects of ethanol on hamster hepatic and extrahepatic monooxygenases were determined in the present study. Chronic ethanol administration increased cytochrome P-450 (P-450) content and monooxygenase activities towards aniline, N-nitrosodimethylamine, and 7-ethoxyresorufin. In contrast, benzphetamine and benzo(a)pyrene oxidation rates were decreased 21-24% by ethanol. In kidney, ethanol pretreatment increased P-450 content, aniline and N-nitrosodimethylamine oxidation activities. In lung, ethanol ingestion selectively increased aniline hydroxylation without affecting other monooxygenase activities. Intestinal monooxygenase activity was refractory to ethanol induction. Immunoblotting of the microsomal proteins showed that ethanol induced a protein cross-reactive with rabbit antibody raised against human P-450 2E1 in hamster liver, kidney, and lung. Immunoblotting analysis using mouse monoclonal antibody 1-12-3 raised against scup P-450 1A1 revealed that ethanol induced an immunorelated protein in hamster liver, kidney, and lung. Induction of P-450 2E1 and 1A was not observed with intestinal protein blots. Immunoblotting analysis using mouse monoclonal antibody 2-66-3 against rat P-450 2B1 showed inhibition of an immunorelated protein in ethanol-treated hamster liver. The inhibitory effect on P-450 2B was not observed with extrahepatic tissues. These results suggest that ethanol has the ability to induce P-450s 2E1 and 1A and to inhibit P-450 2B in hamster tissues.

Metabolism of the antimammary cancer antiestrogenic agent tamoxifen. I. Cytochrome P-450-catalyzed N-demethylation and 4-hydroxylation

Previous studies suggested that the therapeutic effect of the antimammary cancer agent tamoxifen might be related to its metabolism. This study examined the cytochrome P-450 enzymes in rat and human liver catalyzing the metabolism of tamoxifen. Incubations of tamoxifen with rat liver microsomes yielded three major polar metabolites identified as the N-oxide, N-desmethyl, and 4-hydroxy derivatives. N-Oxide formation was catalyzed by the flavin-containing monooxygenase (see part II). Carbon monoxide, SKF-525A, metyrapone, and benzylimidazole strongly inhibited N-demethylation and 4-hydroxylation, indicating the participation of P-450 monooxygenase in these reactions. Antibodies to NADPH-P450 reductase inhibited N-demethylation and 4-hydroxylation. Comparison of the metabolism of tamoxifen in untreated male and female rats demonstrated some sexual dimorphism. N-Demethylation was higher in the male rat and 4-hydroxylation was higher in the female. Treatment of rats with phenobarbital (PB), pregnenolone-16 alpha-carbonitrile (PCN), and methylcholanthrene (MC) enhanced N-demethylation, demonstrating the potential participation of multiple P-450s in N-demethylation. Evidence strongly indicates that CYP3A enzyme(s) catalyzes N-demethylation in liver microsomes of PB- and PCN-treated rats (PB and PCN microsomes, respectively): i) N-demethylation was inhibited by cortisol and erythromycin (alternate substrates) and a time-dependent inhibition was observed with troleandomycin (TAO) in vitro; ii) treatment of female rats with TAO, followed by dissociation of the microsomal TAO-P-450 complex, elevated N-demethylation; iii) treatment of PCN-induced female rats with chloramphenicol inhibited N-demethylation; and iv) polyclonal antibodies (PAbs) to CYP3A1 inhibited N-demethylation in PCN- and PB-treated female rats. Although we were unable to reconstitute the N-demethylation activity with purified CYP3A1, which is difficult to reconstitute, collectively the evidence demonstrated that CYP3A enzymes catalyze N-demethylation in PB and PCN microsomes. By contrast, antibodies against CYP2B1/B2 did not inhibit N-demethylation and reconstituted 2B1 did not catalyze N-demethylation of tamoxifen, indicating that 2B1 was not involved. The increase in N-demethylation by MC treatment appears to be due to elevation of CYP1A1/1A2 (P-450c/d). Alternate substrates of CYP1A1/1A2 inhibited N-demethylation and reconstituted rat CYP 1A1-catalyzed N-demethylation. Surprisingly, monoclonal antibodies (MAbs) against CYP1A1/1A2 only partially inhibited, and PAbs against CYP1A1 did not inhibit N-demethylation in MC microsomes, indicating that in MC microsomes, 1A1 does not contribute significantly to that reaction. Mab anti-CYP2C11/2C6 (P-450h/k) inhibited N-demethylation in PB, PCN, and control male rat liver microsomes, suggesting that CYP2C11 and/or CYP2C6 catalyze this reaction to some extent.(ABSTRACT TRUNCATED AT 400 WORDS)

Hydroxylation and dealkylation of methyl-n-butylnitrosamine and role of certain cytochrome P-450 isozymes in these reactions

We studied the metabolism of methyl-n-butyl-nitrosamine (MBN), a carcinogen for the rat esophagus and liver. The 2-, 3- and 4-hydroxy derivatives were identified as new metabolites of MBN. In studies on tissue slices freshly removed from MRC-Wistar rats, MBN metabolism resembled that of the previously studied methyl-amylnitrosamine in the esophagus catalyzed 2- and 3- hydroxylation; liver, omega-1 hydroxylation; and lung, omega-hydroxylation of both nitrosamines. Liver microsomes from Sprague-Dawley rats catalyzed 2-, 3- and 4-hydroxylation of MBN, as well as the previously studied activating reactions of demethylation and debutylation. Phenobarbital induced all five reactions of MBN bh rat liver microsomes, especially debutylation; 3-methylhol-anthrene induced 3-hydroxylation and debutylation and isoniazid induced demethylation and debutylation. Monoclonal antibodies that inhibit specific cytochrome P-450 isozymes were used to identify the isozymes involved in each reaction. Antibody 4-7-1 appeared more specific than the previously used antibody 2-66-3 for inhibiting P-450 2B1 and/or 2B2. For the metabolism of both MBN and methylamylnitrosamine by rat liver microsomes, the antibody results indicated that P-450 2C11 mainly catalyzed demethylation and omega-1 hydroxylation, P-450 1A1 or 1A2 catalyzed 3-hydroxylation and debutylation or depentylation, P-450 2E1 produced demethylation and P-450 2B1 or 2B2 produced omega-1 hydroxylation, demethylation and debutylation or depentylation.

Cytochrome P450-related differences between rats and mice in the metabolism of benzene, toluene and trichloroethylene in liver microsomes

In evaluating the risks to humans of exposure to chemicals, the results of studies in rodents are sometimes used as a basis for extrapolation. It is therefore important to elucidate differences in metabolism among species. Differences in cytochrome P450-catalysed oxidation of benzene, toluene and trichloroethylene (TRI) between male Wistar rats and male B6C3F1 mice were investigated by immunoblot and immunoinhibition assays using monoclonal antibodies (MAbs) to cytochrome P450 (CYP1A1/2, CYP2B1/2, CYP2E1 and CYP2C11/6). Immunoblot analysis showed that anti-CYP2B1/2 did not detect any protein in either untreated rat or mouse liver microsomes, whereas with anti-CYP2E1 and/or anti-CYP1A1/2 a clear-cut band was seen more in liver microsomes from mice than from rats. Mouse liver microsomes had a greater monooxidation activity for benzene and TRI than rat liver microsomes; mice also had a higher rate of aromatic hydroxylation of toluene at low substrate concentration, but a low rate of side-chain oxidation when a high concentration of toluene was used. The metabolism of benzene was saturated in mice at around 0.23 mM, but the metabolism of the other two solvents was not saturated in either rats or mice at the low concentrations used. Anti-CYP2E1 inhibited the metabolism of benzene, toluene and TRI in microsomes from mice to a greater extent than in rats, while anti-CYP2C11/6 inhibited their metabolism in rats to a greater extent than in mice; anti-CYP1A1/2 inhibited the metabolism of TRI only in microsomes from mice. These results indicate that (i) male B6C3F1 mice have more CYP2E1 and 1A1/2 than male Wistar rats, whereas rats have more CYP2C11/6 than mice; (ii) rats and mice express CYP2B1/2 but they are not immunochemically detectable; (iii) CYP2E1 and 2C11/6 in both species are responsible for the metabolism of benzene, toluene and TRI, whereas CYP1A1/2 in mice catalyses the oxidation of TRI. The differences in the metabolism of benzene, toluene and TRI in rats and in mice may therefore depend, at least in part, on differences in the distribution of P450 isozymes between the two species.

Phenytoin induction of cytochrome P4502B in mice: effects on hexobarbital hydroxylase activity

1. Treatment of ICR and C57BL/6 mice with phenytoin (50 mg/kg, i.p., 3 days) resulted in approximately 33 and 43% increases in hepatic cytochrome P450 levels relative to uninduced microsomes, respectively. Phenytoin treatment caused a 63% decrease in hexobarbital sleeping time in ICR mice (19 versus 52 min). 2. Both Western immunoblot analysis and solid phase radioimmunoassay using monoclonal anti-rat P4502B antibody showed that P4502B was increased significantly in phenytoin-induced mouse microsomes compared with uninduced mice. P4502B9 was the predominantly induced form whereas 2B10 was elevated marginally. Phenytoin was as efficacious as phenobarbital in increasing P4502B. 3. Phenytoin treatment resulted in an approximately 8-fold increase in hexobarbital hydroxylase activity whereas phenobarbital treatment caused an approximately 13-fold increase. Addition of anti-P4502B antibody produced complete inhibition of hexobarbital oxidation in phenytoin-induced microsomes, indicating that raised P4502B in phenytoin-induced microsomes is associated with the increased hexobarbital hydroxylase activity. 4. Phenytoin failed to increase P4501A in either C57BL/6 or ICR mice, as assessed by both immunoblot analysis and metabolic activities. Although both aryl hydrocarbon hydroxylase and 7-ethoxycoumarin deethylase activities were raised approximately two-fold following phenytoin treatment, the metabolic activities were not inhibited by anti-P4501A antibody. 5. These results provide evidence that phenytoin induces P4502B in mice with pronounced increase in hexobarbital hydroxylase activity, and fails to induce P4501A in either C57BL/6 or ICR mice.

Induction of cytochrome P450-dependent monooxygenases in hamster tissues by fasting

The effects of fasting on liver, kidney, and lung monooxygenases were studied using hamsters starved for 4 days. Fasting treatment increased microsomal cytochrome P450 content and NADPH-cytochrome P450 reductase activity in kidney and lung. The treatment caused significant increases of aniline hydroxylation, N-nitrosodimethylamine demethylation, and 7-ethoxycoumarin O-deethylation activities in the liver, kidney, and lung. Fasting caused a threefold increase of benzphetamine N-demethylation activity in lung and a 25% increase in liver and had no effect in kidney. Benzo[a]pyrene hydroxylation activities in the fasted hamster liver, kidney, and lung were higher, lower, and similar to the controls, respectively. Gel electrophoresis of tissue microsomes from control and fasted hamsters revealed that fasting enhanced the intensity of protein band(s) in the P450 molecular weight region. Immunoblotting of the microsomal proteins showed that fasting induced a protein crossreactive with rabbit antibody raised against human P450 2E1 in hamster liver, kidney, and lung. Immunoblotting analysis using mouse monoclonal antibody 2-66-3 raised against rat P450 2B1 revealed that fasting induced an immunorelated protein preferentially in hamster lung, with minimal effects on liver and kidney. Protein blots probed with mouse monoclonal antibody 1-12-3 indicated that fasting induced a protein related to P450 1A1 in hamster liver, kidney, and lung. These results demonstrate that fasting causes a variety of inductive effects on the enzyme components and catalytic activities of monooxygenase systems as well as on the P450s 2E, 2B, and 1A in the hamster tissues.

Studies on the ontogeny of goat hepatic cytochrome P-450-associated O-dealkylase activities using monoclonal antibodies: comparison to adult lung activity

The P-450-associated O-dealkylase activity towards ethoxyresorufin (EROD) and pentoxyresorufin (PROD) was measured in liver microsomes from 1-day-, 1-week-, 4-week-, 6-week-old and adult goats in order to characterize the ontogeny of cytochrome P-450 in this species. The inhibition of these enzyme activities by monoclonal antibodies raised against 3-methyl-cholanthrene-induced (MAb 1-7-1) and phenobarbital-induced (MAb 2-66-3) rat hepatic cytochrome P-450 was used to measure the contribution of the MAb-defined, epitope-specific P-450 to the total activities during these ages of goat development. EROD activity was undetectable until the 1st week of life and increased more than 25-fold by 4 weeks of age. The inhibition of EROD by MAb 1-7-1 increased from 20% in 1-week-old to 70% in adult goats. PROD activity, however, was detectable in the 1-day-old and reached adult levels by 6 weeks of age. The maximal inhibition (40%) of PROD activity by MAb 2-66-3 was demonstrated in 1-day-old goats. The measurement of these enzyme activities and their inhibition by the monoclonal antibodies demonstrated major differences in the ontogeny of these P-450 isozymes in goats. On the other hand, adult goat lung lacked detectable PROD activity, while it expressed approximately one tenth of the EROD activity exhibited by the liver. Over 70% of this activity was inhibitable by MAb 1-7-1.

Chest wall configuration assessed at total lung capacity during acute asthma and after recovery

During acute asthma reversible increase in lung compliance and total lung capacity (TLC) have been observed. The magnitude of the increase in TLC, however, was found to be relatively small when TLC was measured radiographically. We wondered if structural distortion of the respiratory bellows develops during acute asthma attacks, accounting for the limited increase in TLC. We analyzed the chest wall dimensions using chest roentgenograms obtained in 32 patients who had previously participated in the study of radiographic evaluation of TLC. We found that the dimensional changes accompanying the small increase in TLC during acute asthma were nonuniform, consisting of mainly an increase in lung height (0.45 +/- 0.15 cm) with limited coordinated expansion of other dimensions and a small but significant distortional contraction of lung width at the lowest portion of the rib cage (-0.25 +/- 0.12 cm). These findings were interpreted to mean that in response to the decrease in elastic lung recoil (internal load) occurring during acute asthma, the diaphragm makes limited but effective further caudad descent without provoking serious structural distortion and that rib cage muscles, working at mechanical disadvantage at high lung volume, act largely as fixators.

Cloning and characterization of cDNAs coding for heavy and light chains of a monoclonal antibody specific for pre-S2 antigen of hepatitis B virus

Binding specificity of a monoclonal antibody (mAb) (kappa, gamma 2b) H8 which can react with the pre-S2 peptide of hepatitis B virus (HBV) was determined by Western blot analyses. From the hybridoma cell line secreting mAb H8, poly(A)+ RNA was prepared and used as a template for cDNA synthesis and cloning. Full-length cDNAs coding for the heavy and kappa light chains of the mAb were cloned from the cDNA library and characterized by nucleotide (nt) sequence analyses and N-terminal amino acid sequencing. The sequence analyses revealed that both heavy and light chain-specific cDNAs are functional, and the variable regions of the heavy and light chains are members of mouse heavy chain subgroup III(c) and light chain group I, respectively. Comparison of the nt sequences with mouse immunoglobulin genes listed in the GenBank data base show that the cDNAs have not been previously reported. The cDNAs will be used for the construction of a therapeutic antibody for HBV infection.

7-Alkoxyquinoline O-dealkylation by microsomes from human liver and placenta

1. The O-dealkylation of seven 7-alkoxyquinoline derivatives by human hepatic and placental microsomes and the effect of maternal cigarette smoking on placental 7-alkoxyquinoline metabolism was studied. 2. None of several monoclonal antibodies to isoenzymes of cytochrome P450 had a clear effect on metabolism of the compounds by liver microsomes. 3. Maternal cigarette smoking induced the O-dealkylation of all of the 7-alkoxyquinoline derivatives, being greatest for 7-butoxy- and 7-benzyloxyquinoline. 4. Placental 7-alkoxyquinoline metabolism induced by smoking was partially inhibited by the monoclonal antibody 1-7-1 raised against 3-methylcholanthrene-induced rat liver P450. 5. None of the 7-alkoxyquinoline O-dealkylations could be assigned specifically to any known P450 isoenzyme in human liver or placenta.

Endobronchial tuberculosis. Clinical and bronchoscopic features in 121 cases

The clinical and bronchoscopic features of endobronchial tuberculosis in 121 patients were retrospectively investigated. The peak incidence occurred in the second decades, with 3.8 times higher incidence noted in female than in male subjects. A barking cough with sputum was the most common chief complaint in 61.1 percent. Parenchymal infiltration and/or consolidation was the most common roentgenographic finding of the chest in 58.6 percent. Hypertrophy with luminal narrowing was the most common bronchoscopic finding in 43 percent. Bronchoscopically, right upper and right main bronchus were the most frequently involved in 30.5 percent. It was concluded from these data that using fiberoptic bronchoscopy allows not only substantial meaningful assessment of endobronchial tuberculosis but also relieves atelectasis eventually resulting in successful treatment with antituberculosis drugs.

Differential oxidase activity of hepatic and pulmonary microsomal cytochrome P-450 isozymes after treatment with cytochrome P-450 inducers

Phenobarbital, 3-methylcholanthrene, acetone and pyrazole were used as inducers of cytochrome P450 and the NADPH-dependent oxidase activity (O-2 production) of pulmonary and hepatic microsomes was determined. Oxidase activity of microsomes from 3-methylcholanthrene-treated rats was significantly decreased as compared to that of controls when expressed on the basis of cytochrome P450 content (30% decrease for liver, 60% decrease for lung). The oxidase activity of liver microsomes from pyrazole-treated rats showed a significant increase, whereas phenobarbital treated microsomes had average superoxide-generating activity. The contribution of cytochromes CYP 1A, CYP 2B and CYP 2E1 to superoxide-generating activity was investigated using monoclonal antibodies. Monoclonal antibody 1-91-3 against CYP 2E1 inhibited superoxide generation by 58% in liver microsomes from pyrazole-treated rats. Monoclonal antibodies 1-7-1 and 2-66-3 against CYP 1A and CYP2B, respectively, had no effect on superoxide generation. These results indicate that different cytochrome P450 isoforms are mainly responsible for differential superoxide generating activities of microsomes and complement the reconstitution study of Morehouse and Aust. Furthermore, our study indicates that CYP 1A1, induced by 3-MC, demonstrates an unusually low oxidase activity.

The first branchial cleft carcinoma

Primary branchiogenic carcinoma was previously a debated entity. Initially it was a popular diagnosis for many cystic carcinomas of the neck. Then, in 1950, stringent criteria were defined for establishing the diagnosis of primary branchiogenic carcinoma. Only a limited number of cases have successfully fulfilled these criteria. We describe a patient who meets the criteria and who we believe represents the first reported case of a carcinoma arising from the vestigium of the first branchial cleft. We also review the literature on branchial cleft carcinomas and discuss the diagnosis, histopathologic features, and therapeutic options.

Sex-, age- and pregnancy-induced changes in the metabolism of toluene and trichloroethylene in rat liver in relation to the regulation of cytochrome P450IIE1 and P450IIC11 content

Sex-, age- and pregnancy-induced changes in the metabolism of toluene and trichloroethylene in rat liver were investigated in relation to the regulation of cytochrome P450IIE1 and P450IIC11 content using monoclonal antibodies. Immature male rats had a higher level of microsomal protein than females, and this increased with development; however, no difference by sex was found at puberty. No difference in cytochrome P450 content was seen between immature male and female rats; the content increased with development only in males, so that a sex difference in cytochrome P450 content occurred at puberty. Pregnancy decreased the cytochrome P450 content but not that of the microsomal protein. The rate of formation of benzyl alcohol from toluene was 4 times higher in mature than in immature male rats at a high concentration of toluene, but no difference was seen at a low toluene concentration. In contrast, the rate was lower in mature female rats than in immature ones at a low toluene level and no difference was seen at the high concentration. A sex difference was thus found in benzyl alcohol formation at puberty at both concentrations of toluene. The levels of o- and p-cresol formation in liver were similar in males and females but the rate decreased during development of females. The rate of metabolism of trichloroethylene was higher in immature than in mature male and female rats, especially at a low substrate level, and no sex difference in metabolism was seen with either age or concentration of trichloroethylene. Pregnancy decreased the metabolism of both toluene and trichloroethylene.(ABSTRACT TRUNCATED AT 250 WORDS)

The medical treatment of a tuberculous tracheo-oesophageal fistula

Tracheo-oesophageal (TE) fistulas caused by Mycobacterium tuberculosis are rare and usually require both surgical treatment and medical treatment with antituberculosis drugs. A patient with a tuberculous TE fistula and mediastinal lymphadenitis was successfully treated by medical management alone.

Monoclonal antibodies to rat liver microsomal cytochrome b5

Hybridomas obtained by the fusion of spleen cells from rat cytochrome b5-immunized mice with mouse myeloma cells produced five groups of monoclonal antibodies (MAbs) with three mouse immunoglobulin subtypes: IgG1, IgG2b and IgM. All of the MAbs bound strongly to rat cytochrome b5 as measured by radioimmunoassay (RIA). Four clones of MAbs were also strongly immunoreactive with cytochrome b5 when tested by Western blotting, but only one of the MAbs (1-39-2) weakly immunoprecipitated cytochrome b5 in an Ouchterlony double-immunodiffusion test. Two of the MAbs partially inhibited cytochrome b5-mediated NADH cytochrome c reduction catalyzed by liver microsomes (24-36%). Expression of immunodetectable cytochrome b5 was highest in the liver, next highest in the kidney, and quite low in the other tissues examined with MAb 1-17-1 by Western blotting. This MAb recognized homologous cytochrome b5 of human liver microsomes and in homogenates of TK- cells infected with recombinant vaccinia virus encoding human cytochrome b5. These MAbs to cytochrome b5 will be useful for the identification, quantification, and purification of cytochrome b5 from animal and human tissues, and for understanding its role in cytochrome P450 catalyzed drug metabolism and carcinogen activation with respect to tissue, organ and individual differences.

Persistent effects of a single dose of Aroclor 1254 on cytochromes P450IA1 and IIB1 in mouse lung

The polychlorinated biphenyl mixture Aroclor 1254 has been shown to elicit prolonged biochemical responses in several rodent species, particularly induction of mixed function oxygenases in hepatic tissue. Lung is also of interest since a single dose of Aroclor 1254 has been demonstrated to have a tumor promoting effect, increasing the numbers of lung tumors in Swiss mice initiated with N-nitrosodimethylamine. To investigate the enzyme induction response in lung, male Swiss mice were given a single 100 or 500 mg/kg dose of Aroclor 1254 and euthanized at time intervals ranging from 48 hr to 30 weeks. Both cytochromes P450IA1 and IIB1 were followed by use of specific enzyme activities and Western immunoblotting. The IA1 isoform, as quantified by ethoxyresorufin-O-deethylase activity and immunoblotting with monoclonal antibody 1-7-1, was significantly elevated for 30 weeks after both doses. In contrast, benzyloxy-resorufin-O-dealkylase activity (P450IIB1 specific), which is constitutively expressed in rodent lung, was unaffected by Aroclor treatment at the lower dose at early time points, but induced twofold at 30 weeks. At the higher dose, however, enzymatic activity was decreased to 50% of control values, an effect which persisted for 4 weeks postexposure. These changes were confirmed by Western immunoblotting utilizing monoclonal antibody 2-66-3. Concomitantly, content of individual PCB congeners in lungs and carcass was quantified by gas chromatography with electron capture detection. One congener, 2,3,3',4,4'-pentachlorobiphenyl, was selectively retained in lung compared to carcass. Lack of correlation between changes in lung content of PCBs and levels of the P450 isoforms suggested interactions between congeners in control of P450 induction and repression. These data confirm a prolonged P450 induction response in nonhepatic tissue following Aroclor exposure, and further suggest a bidirectional role for certain PCB congeners in the regulation of P450IA1 and P450IIB1 expression in lung tissue.

Anatomical observation on draining patterns of saphenous tributaries in Korean adults

This study was done to identify the normal and variants of saphenous tributaries in Korean adults. The pattern of confluence of saphenous tributaries, medial accessory saphenous, lateral accessory saphenous, superficial epigastric, superficial circumflex iliac and superficial external pudendal veins, was carefully examined in 249 lower limbs (right, 129; left, 120) of embalmed Korean cadavers (73 males & 56 females). The medial accessory saphenous vein drained into the great saphenous vein directly (in 82.3%) or by a common trunk (in 17.7%) with the superficial epigastric or superficial external pudendal vein. The lateral accessory saphenous vein entered the great saphenous (in 67.1%) or the femoral vein (in 32.9%) directly or, forming a common trunk with other saphenous tributaries. The superficial epigastric vein joined the great saphenous (in 77.1%) or the femoral vein (in 22.9%) directly or, by a common trunk with other saphenous tributaries. The superficial circumflex iliac vein reached the great saphenous (in 83.1%) or the femoral vein (in 16.9%) directly or, by a common trunk with other saphenous tributaries. The superficial external pudendal vein opened into the great saphenous (in 95.2%) or the femoral vein (in 4.8%) directly or by a common trunk with other saphenous tributaries. In Koreans, the incidence of the normal pattern of saphenous tributaries was 23.7% and in 76.3% any one of variant saphenous tributaries entered the femoral or the great saphenous vein by a common trunk with other saphenous tributaries.

Variations of the ventral rami of the brachial plexus

We studied the variations in the ventral rami of 152 brachial plexuses in 77 Korean adults. Brachial plexus were composed mostly of the fifth, sixth, seventh and eighth cervical nerves and the first thoracic nerve (77.0%). In 21.7% of the cases examined, the fourth, fifth, sixth, seventh and eighth cervical and the first thoracic nerves contributed to the plexus. A plexus composed of the fourth, fifth, sixth, seventh and eighth cervical and the first and second thoracic nerves, and a plexus composed of the fifth, sixth, seventh eighth cervical nerves were also observed. The plexuses were classified into three groups according to cephalic limitation, and the plexus of group 2 in which the whole fifth cervical nerve enters the plexus, were observed the most frequent. The average diameter of the sixth and the seventh cervical ventral rami of the plexus was greatest and that of the fifth cervical was smallest. The largest nerve entering the plexus was the sixth or the seventh cervical nerve in about 79% of cases. The dorsal scapular nerve originated from the fifth cervical ventral ramus in 110 cases (75.8%). The long thoracic nerve was formed by joining of roots from the fifth, sixth, and seventh cervical nerves in 76.0% of cases. Also, a branch to the phrenic nerve, the suprascapular nerve, a nerve to the pectoralis major muscle and a nerve to the subscapular muscle arising from the ventral rami of the plexus were observed.

The time-dependent increase in the binding of benzo[a]pyrene to DNA through (+)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide in primary rat hepatocyte cultures results from induction of cytochrome P450IA1 by benzo[a]pyrene treatment

The proportion and amount of benzo[a]pyrene (B[a]P) that binds to DNA through the carcinogenic (+)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide [(+)-anti-BPDE] increases with time of exposure to B[a]P in cell cultures derived from a number of species. Pretreatment of primary rat hepatocyte cultures for 12 h with 1 microgram B[a]P/ml medium increased the subsequent metabolism of [3H]B[a]P by 47% and [3H]B[a]P-DNA binding by 53% compared with acetone-pretreated hepatocytes. The amount of (+)-anti-BPDE bound to DNA in the B[a]P-pretreated hepatocytes increased 175%. B[a]P pretreatment also increased DNA-binding 2-fold in hepatocytes treated with [3H]7,8-dihydroxy-7,8-dihydro-B[a]P but had no effect on DNA binding in cells treated with anti-B[a]P-7,8-diol-9,10-epoxide. Western blotting showed that cytochrome P450IA1, which was not detectable prior to B[a]P treatment, was selectively increased by B[a]P treatment. A monoclonal antibody that specifically inhibits cytochrome P450IA1 reduced the binding of B[a]P to DNA by greater than 90% in microsomal preparations from B[a]P-pretreated hepatocytes. These results indicate that the time-dependent increase in the formation of (+)-anti-BPDE-DNA adducts results from an increase in the amount and proportion of B[a]P metabolized to this ultimate carcinogen by P450IA1 that is induced by the B[a]P treatment. The importance of P450IA1 induction by the B[a]P for its activation to this ultimate carcinogenic metabolite suggests that long-term exposure of cells to B[a]P could result in activation of a higher proportion of the B[a]P to the carcinogenic (+)-anti-BPDE.

A comparative study on the contribution of cytochrome P450 isozymes to metabolism of benzene, toluene and trichloroethylene in rat liver

The contribution of P450IIE1, P450IIC11/6, P450IIB1/2 and P450IA1/2 to the formation of chloral hydrate (CH) from trichloroethylene (TRI) was investigated in microsomes from control, ethanol-, phenobarbital (PB)- and 3-methylcholanthrene (MC)-treated rats using monoclonal antibodies (MAbs) to the respective P450 isozymes, and compared with their roles in benzene and toluene metabolism. Anti-P450IIE1 inhibited the formation of CH from TRI more strongly in microsomes from ethanol-treated rats than in microsomes from control rats at low concentration of TRI when net inhibition was compared. Anti-P450IIC11/6 inhibited CH formation in microsomes from control and PB-treated rats at high, not low, concentration of TRI, but the net inhibition in control microsomes was less than that due to anti-P450IIE1. Anti-P450IIB1/2 and anti-P450IA1/2 also inhibited CH formation from TRI in microsomes from PB- and MC-treated rats, respectively, stronger at high substrate concentration than at low concentration. These results indicate that P450IIE1, P450IIC11/6, P450IIB1/2 and P450IA1/2 are involved in the metabolic step from TRI to CH, and the first isozyme may be a low-Km TRI oxidase and the others high-Km one. Comparing the contributions of four isozymes to benzene, toluene and TRI metabolism, all four acted in the metabolism of these compounds, but P450IIE1 did not catalyse o-cresol formation nor P450IA1/2 benzyl alcohol formation from toluene, suggesting regioselectivity of toluene metabolism in the action of these two isozymes. The contribution of P450IIE1 in benzene and TRI oxidation was greater than that of P450IIC11/6, but the reverse was seen with respect to benzyl alcohol formation from toluene, indicating that P450IIC11/6 is relatively inactive towards benzene and TRI oxidation, but is primarily involved in toluene metabolism. P450IIB1/2 and P450IIC11/6 attacked all the metabolic positions studied, but only in the side-chain metabolism of toluene was their contribution significant, suggesting that these two isozymes are quite similar in function.

Mediastinal pancreatic pseudocyst with recurrent pleural effusion. Demonstration by endoscopic retrograde cholangiopancreatogram and subsequent computed tomography scan

Mediastinal pseudocysts of internal pancreatic fistulas are rare as a cause of bilateral pleural effusions even in relapsing pancreatitis. We describe a 38-year-old man with recurrent bilateral pleural effusion as a complication of a pancreatic pseudocyst. Extension of a pancreatic pseudocyst into the posterior mediastinum was clearly identified by endoscopic retrograde cholangiopancreatogram and subsequent computed tomography scan of the abdomen and chest, and the complication was successfully treated by surgical management. We stress the importance of definite assessment of the communication of pancreatic pseudocyst with mediastinum in patients with pancreatitis who develop recurrent pleural effusions.

Distribution of cytochrome CYP2E1 in murine liver after ethanol and acetone administration

The effects of acetone and ethanol administration on cytochrome CYP2E1 in murine liver were investigated. A monoclonal antibody (Mab 1-98-1) specific to rat ethanol-inducible P450 recognized a major band of Mr 51,000 in Western immunoblots of mouse liver microsomes. This band was increased 1.8-fold by 10% ethanol in drinking water for 2 weeks, 4.7-fold by 1% acetone in drinking water for 1 week, and 2.5-, 2.1- and 6.8-fold by ethanol in a liquid diet for 9 days, 2 weeks and 3 weeks respectively. Immunohistochemical staining experiments with the same antibody showed specific localization in centrilobular regions of liver lobules, with variations in intensity that corresponded to differences detected in Western immunoblots. Uniform cellular increases in centrilobular staining occurred with all ethanol treatments, whereas a more heterogeneous increase in individual cells was noted after acetone. Lipid accumulation in hepatocytes was pronounced after 3 weeks on the ethanol liquid diet but was less so in other treatment groups, and thus did not consistently correlate with enzyme induction. Microsomal aniline p-hydroxylase activity was also induced by the acetone and ethanol treatments, with a progressive increase from 9 days to 3 weeks on the ethanol liquid diet. Changes in this activity in general paralleled those found with immunohistochemistry and immunoblotting. The results demonstrate that (i) the mouse is a good model for correlative biochemical and histochemical studies of CYP2E1 induction, (ii) in the mouse liver, this P450 is preferentially localized in centrilobular regions constitutively as well as in induced states, (iii) the centrilobular pattern varies under different induction conditions, and (iv) there is a progressive inductive increase in CYP2E1 protein and enzyme activity with chronic ethanol treatment over at least 3 weeks.

Immunochemical detection of cytochrome P450 isozymes induced in rat liver by n-hexane, 2-hexanone and acetonyl acetone

Cytochrome P450 isozymes induced in rat liver by treatment with n-hexane, 2-hexanone and acetonyl acetone (given intraperitoneally 5 mmol/kg for 4 days) were investigated using enzyme assays (benzene, toluene, 7-ethoxyresorufin and 7-pentoxyresorufin metabolism) and monoclonal antibodies (anti-P450IA1/2, anti-P450IIB1/2, anti-P450IIC11/6, anti-P450IIE1(91) and anti-P450IIE1(98)). n-Hexane treatment enhanced the activities of low-Km benzene aromatic hydroxylase and toluene side-chain oxidase, but not 7-ethoxyresorufin O-deethylase or 7-pentoxyresorufin O-depentylase. 2-Hexanone or acetonyl acetone treatment enhanced the activities of low- and high-Km benzene aromatic hydroxylases, toluene side-chain oxidase and 7-pentoxyresorufin O-depentylase, but not of 7-ethoxyresorufin O-deethylase. Immunoblot analysis showed that anti-P450IA1/2 did not bind liver microsomal protein from either control and treated rats in the region of cytochrome P450s, whereas with anti-P450IIE1(98) a clear-cut band was seen in liver microsomes from control and treated rats, with intensities in the following order: 2-hexanone = acetonyl acetone greater than or equal to n-hexane greater than control greater than phenobarbital. With anti-P450IIB1/2, a band was detected in microsomes from phenobarbital-treated rats, and to a lesser extent, in microsomes from 2-hexanone- and acetonyl acetone-treated rats. Like the immunoblot analysis, anti-P450IIE1(91) inhibited toluene side-chain hydroxylase activity in all microsomes, except in preparations from phenobarbital-treated rats and anti-P450IIB1 in microsomes from phenobarbital-, 2-hexanone- and acetonyl acetone-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)