[AHH activity and life environmental factors]

To investigate life environmental factors which affect aryl hydrocarbon hydroxylase (AHH) activity, basal and 3-methylcholanthrene(3-MC)-induced AHH activities were determined by the formation of 3-hydroxybenzo(a)pyrene in cultured lymphocytes obtained from 111 healthy male subjects who lived in Fukuoka Prefecture, Japan. Fold induction (3-MC-induced/basal) was calculated. Relationship between the absolute activities and the fold induction of AHH and life environmental factors was statistically examined. Study of simple correlation indicated the following: Basal AHH activity was positively correlated with age and habitual intake of drugs. Induced AHH activity was positively correlated with coffee intake, smoking and habitual intake of drugs. Fold induction was positively correlated with coffee intake and smoking, and negatively with age. Using multiple regression analysis, habitual intake of drugs showed positive relation to both basal and induced enzyme activity, and age showed positive relation to the basal activity and negative relation to the fold induction.

Depression of peripheral blood monocyte aryl hydrocarbon hydroxylase activity in patients with liver disease: possible involvement of macrophage factors

Aryl hydrocarbon hydroxylase activity was detectable in cultured macrophage monolayers of peripheral blood monocyte origin. Peripheral blood monocytes were isolated from patients with biopsy-confirmed liver disease and healthy volunteers. Macrophage monolayers were prepared and incubated at 37 degrees C. After 24 hr, the aryl hydrocarbon hydroxylase activity and cellular protein concentration were assayed on cell homogenates. The monocyte aryl hydrocarbon hydroxylase activity in cultured macrophages from normal volunteers was 1.23 +/- 0.16 (n = 19). The aryl hydrocarbon hydroxylase activity in macrophage cultures from patients with biopsy-confirmed liver disease was 0.48 +/- 0.05 (n = 20). This represents a significant (61%) decrease in monocyte aryl hydrocarbon hydroxylase compared to controls. The 20 patients have established cirrhosis or early stage liver disease. The established cirrhosis group includes alpha 1-antitrypsin deficiency-associated cirrhosis; primary biliary cirrhosis; alcoholic (Laennec's) cirrhosis; cryptogenic cirrhosis, and hemochromatosis. Early stage liver disease is attributed to methotrexate (Stage III), early stage primary biliary cirrhosis and alpha 1-antitrypsin deficiency. Our results indicate that the depression in monocyte aryl hydrocarbon hydroxylase activity is greater in patients with established cirrhosis than early stage liver disease. Our results further suggest that cultured monocytes from patients with liver disease spontaneously release soluble factors into the culture medium. Incubation of this medium, containing macrophage factors, with isolated hepatocytes significantly depress hepatocyte aryl hydrocarbon hydroxylase activity compared to medium obtained from cultures of monocytes from normal volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

[Smoking and induction of the enzyme aryl hydrocarbon hydroxylase in patients with laryngeal carcinomas and precancerous conditions]

The risk for a smoker of developing cancer of the larynx depends on the activity of the enzyme arylhydroxcarbonhydroxylase in his cells. The higher the genetically determined arylhydroxcarbonhydroxylase activity, the higher is the probability of developing the disease.

Monooxygenase activity of human hemoglobin: role of quaternary structure in the preponderant activity of the beta subunits within the tetramer

Catalysis of para hydroxylation of aniline was measured for human ferrihemoglobin and various derivatives in a reconstituted system consisting of the appropriate hemoprotein (at 4 microM heme), reduced nicotinamide adenine dinucleotide phosphate (NADPH), cytochrome P-450 reductase, and aniline under atmospheric O2. The isolated subunits of hemoglobin (alpha 3+ and beta 3+4) were prepared by treatment with p-(hydroxymercuri)benzoate. Semihemoglobin (alpha heme2 beta 02) was prepared from ferrihemoglobin and apohemoglobin. Converse valency hybrids alpha 3+2(beta 2+-CO)2 and (alpha 2+-CO)2 beta 3+2 were prepared from appropriately ligated alpha and beta subunits. After chromatography, the hemoglobin derivatives were characterized by visible and 1H NMR spectroscopy and electrophoresis. At the same concentration of aniline, the alpha and beta subunits were much less active than the normal tetramer. alpha-Semihemoglobin and the alpha 3+2(beta 2+-CO)2 hybrid also displayed lower hydroxylase activity. The (alpha 2+-CO)2 beta 3+2 hybrid was about as active as normal alpha 3+2 beta 3+2. This result suggests that the activity of tetrameric hemoglobin primarily involves the beta subunits. Also transfer of the beta subunits from the beta 4 molecular environment to the alpha 2 beta 2 state enhances their monooxygenase activity approximately 15-fold. The hemoglobin derivatives were differently susceptible to substrate inhibition, the beta 4 species being most sensitive. Estimates of Vmax from the linear portions of the corresponding Lineweaver-Burk plots showed agreement within a factor of 2.5 for all of the hemoglobin derivatives, suggesting that the intrinsic O2-activating capacities of the derivatives are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Monooxygenase activity of human hemoglobin: NMR demonstration of different modes of substrate binding corresponding to different activities of hemoglobin derivatives

In the accompanying paper [Ferraiolo, B. L., Onady, G. M., & Mieyal, J. J. (1984) Biochemistry (preceding paper in this issue)] we reported different aniline hydroxylase activities for ferrihemoglobin, its isolated subunits, and the converse pair of valency hybrids alpha 3+2(beta 2+-CO)2 and (alpha 2+-CO)2 beta 3+2 in a reconstituted system containing reduced nicotinamide adenine dinucleotide phosphate (NADPH) and cytochrome P-450 reductase. To investigate the molecular basis for the different activities, 1H NMR T1 relaxation studies of aniline were performed in the absence and presence of each of the hemoglobin (Hb) species. The paramagnetic contribution of the ferric heme iron atoms of each Hb derivative to the enhanced relaxation of the proton nuclei of aniline was determined relative to control experiments in which the hemoproteins had been converted fully to the corresponding (carbonmonoxy)ferrous forms, which are diamagnetic. According to the known distance dependence of the paramagnetic effect and the relative changes in T1 for the upfield and downfield signals in the spectrum of aniline, it was ascertained that aniline binds in the same manner to the beta-ferric hybrid and to ferrihemoglobin. These two forms displayed equivalent hydroxylase activities that were the highest among the Hb derivatives for the same aniline concentration. The T1 changes observed with the alpha-ferric hybrid suggest a different orientation for aniline in that complex. The T1 data for the isolated subunits alpha 3+ and beta 3+4 would indicate that overall binding of aniline includes a component of direct aniline-heme ligation in each case.(ABSTRACT TRUNCATED AT 250 WORDS)

Aryl hydrocarbon hydroxylase induction levels in patients with malignant tumors associated with smoking

The levels of aryl hydrocarbon hydroxylase (AHH) inducibility were assessed in 173 patients with cancers statistically associated with smoking, i.e., squamous cell and transitional cell carcinomas, at various sites. In 34 patients with carcinomas of the oral cavity, 41 patients with laryngeal carcinomas, and 22 patients with pulmonary carcinomas there was a highly significant overrepresentation of high inducers, whereas 30 patients with carcinomas of the renal pelvis and ureter and 46 patients with urinary bladder carcinomas did not differ significantly in this respect from a control population comprising 92 subjects with no history of neoplastic disease. The results add further support to the concept of AHH as a major activator of carcinogens belonging to the group of polycyclic aromatic hydrocarbons (PAH) when these affect the oral cavity and/or the respiratory tract. The role of AHH in urothelial carcinogenesis seems to be less explicit.

Alterations in leukocyte aryl hydrocarbon hydroxylase activity associated with treatment and age in psoriasis patients and healthy individuals

We have examined the relationship between topical psoriasis treatment and the activity of the mixed function oxidase, aryl hydrocarbon hydroxylase (AHH), in peripheral blood monocytes and lymphocytes from 20 patients with psoriasis. These data were compared to monocyte and lymphocyte AHH activity measured in 20 normal subjects. AHH activity was determined in cells induced with benzanthracene and in uninduced control cells. Monocyte and lymphocyte AHH activity in six untreated psoriasis patients was similar to that in the healthy controls. AHH activity in either uninduced or induced monocytes showed an increase with age in both the healthy and the untreated psoriatic subjects. Lymphocytes from the healthy subjects showed an age-related decline in enzyme activity. Fourteen patients with psoriasis receiving topical tar and/or topical corticosteroid therapy had significantly higher (P less than 0.05) levels of basal and induced monocyte and lymphocyte AHH activity than the healthy controls. AHH activity is age-related and appears to be controlled differently in monocytes and in lymphocytes. AHH activity in circulating monocytes and lymphocytes may be stimulated by topical tar and/or steroid therapy of psoriasis.

Blood monocyte aryl hydrocarbon hydroxylase activity in psoriasis

The activity of aryl hydrocarbon hydroxylase (AHH) in monocytes from 13 healthy control subjects and in 16 patients with discoid psoriasis was measured. The mean basal monocyte AHH activities of the control and psoriatic groups were 3.4 +/- 0.47 and 4.46 +/- 0.55 respectively (pmol 3-OHBP h-1 10(-6) cells). This difference was not significant. The mean induced monocyte AHH activities in the control and psoriatic groups were 56.4 +/- 10.8 and 77.8 +/- 16.0 pmol 3-OHBP h-1 10(-6) cells respectively but this difference was not significant. The mean induction ratios in the control and psoriatic groups were 16.5 +/- 1.8 and 20.4 +/- 3.6 respectively. Again, this difference was not significant. We conclude therefore, that monocyte aryl hydrocarbon hydroxylase activity is not reduced in psoriasis.

Aryl hydrocarbon hydroxylase activity in cultured lymphocytes of psoriatic patients

To evaluate further the metabolic capacity of psoriatics, the activities and inducibility of aryl hydrocarbon hydroxylase (AHH) were measured in cultured mitogen-stimulated lymphocytes from the peripheral blood of 68 psoriatic and 39 control patients. There was no significant difference in the mean basal and induced AHH activities between the psoriatics and the controls, although the former showed a slight tendency towards a higher inducibility ratio. In both, the basal and induced AHH values decreased significantly with increasing age. The cigarette smokers in both groups had significantly higher AHH activities than the nonsmokers. Antipsoriatic treatment (Anthralin, PUVA) did not seem to influence the lymphocyte AHH activities. No association was demonstrable between the AHH activities and the duration of the disease.

A method for detecting aryl hydrocarbon hydroxylase activities in cryopreserved human lymphocytes

Aryl hydrocarbon hydroxylase (AHH) activity, NADH-dependent cytochrome c reductase (cyt c) activity, and [3H]thymidine (3H-TdR) incorporation were monitored in human lymphocytes cryopreserved for periods up to 1 year. A standard procedure for freezing, thawing and culturing of these lymphocytes was developed. Kinetics for expression of benz[a]anthracene-(BA)-induced AHH activity, cyt c activity, and 3H-TdR incorporation were similar in both freshly cultured and cryopreserved cells. Lymphocyte samples from 10 individuals were collected once per month over a 3-month period and cells were either cultured at the time of donation or cryopreserved for later assay. Results indicated that the cryopreserved lymphocytes efficiently responded to mitogen activation. The intra-individual variation in AHH activities was reduced in the cryopreserved lymphocytes compared to the freshly cultured cells, and the relative ranking of these individuals in terms of their AHH activities remained constant for both fresh and cryopreserved samples. Cryopreservation seems to offer significant advantages over the freshly cultured lymphocytes because it allows for lymphocyte samples to be collected in diverse geological locations and over extended periods of time and yet permits for the culture and assay of all the cell samples at exactly the same time.

The effect of an individual's blood pressure on the percentage of total 7,12-dimethylbenz[a] anthracene metabolites that bind covalently to DNA in cultured resting lymphocytes

A method for the quantitative analysis of the percent metabolism that results in covalent binding of 7,12-dimethylbenz[a]anthracene (DMBA) to DNA in viable resting human lymphocytes is described. The inter- and intra-experimental reproducibility as judged by the coefficient of variation and examined in the same individual over a 3-month period was 31.4% and 13.9%, respectively. When the lymphocytes from 30 hypertensive individuals were exposed to 1 microM DMBA for 18 h, the percent of total DMBA metabolites that bind DNA covalently was correlated to the blood pressures of the patients at the time of sampling (r = 0.53, P less than 0.005). No influences on the data from the type or duration of hypertensive drug treatment could be statistically determined for this sample of hypertensive patients. It was concluded that high blood pressure is a strong determinant in predisposing lymphocytes to increased genetic risk from induced DNA damage and that this relationship is not statistically affected by hypertensive drug therapy.

Mixed function oxidase and glutathione S-transferase activities in normal human peripheral blood lymphocytes

The carcinogenic activity of some chemicals may be related to uncoupling of metabolism mediated by the mixed function oxygenase system. The intermediate formation of reactive epoxides or hydroxylamines may be eliminated by glutathione S-transferase. The ratio between these 2 enzymic activities may indicate if individuals are prone to cancerous development. If adequate cellular samples are available, assay of these enzymes may be used to trace individuals at risk. Therefore the present paper estimates these 2 enzymic activities (i.e., aryl hydrocarbon hydroxylase (AHH) and N-demethylation, the metabolite forming enzyme activities and glutathione S-transferase, the metabolite detoxifying enzymes), in the peripheral blood lymphocytes of 35 subjects. Their median age was 34 years. AHH activity was increased by 52% in the lymphocyte homogenate and by 45% in the microsomal fraction of smokers when compared with non-smokers. The enzyme activity also increased by 73% in the homogenate and by 93% in the microsomes of those taking drugs. The activity of N-demethylase increased by 212% in microsomes of smokers. However, the glutathione S-transferase activity decreased by about 2% in the lymphocyte homogenate and cytosol of smokers. The subjects taking drugs showed a decrease in this enzyme activity by 8% in the homogenate and by 37% in the cytosol.

High-pressure liquid chromatographic analysis of benzo(a)pyrene metabolism by human lymphocytes from donors of different aryl hydrocarbon hydroxylase inducibility and antipyrine half-lives

With high-pressure liquid chromatography (HPLC), lymphocytes from six human donors were evaluated for their ability to metabolize benzo(a)pyrene (BP). Donors whose aryl hydrocarbon hydroxylase (AHH) inducibility ratios ranged from 2.4 to 4.6 and whose antipyrine plasma half-lives ranged from 8 to 17 hr were examined. The BP metabolites identified were: 7,8-dihydrodiol, quinones, and 9-hydroxy and 3-hydroxy phenols. HPLC profiles of BP metabolites elaborated by uninduced (control) and benz(a)anthracene-induced lymphocytes were qualitatively similar among the six donors. A good correlation (r = 0.79) was found between known AHH inducibility ratios for the donors, as determined by the conventional fluorometric AHH assay, and induction of BP phenol production quantitated from HPLC data. HPLC results also indicated that the induction of benzo(a)pyrene-7,8-dihydrodiol, the proposed proximate carcinogenic form of BP, did not parallel BP phenol induction. Furthermore, the data also indicated a good negative correlation between AHH inducibility and the measurements of plasma antipyrine or urinary 4-hydroxyantipyrine half-lives (r = -0.88 or -0.91), respectively.

Effect of tumor promoters on induction of aryl hydrocarbon hydroxylase in human lymphocytes

The induction of aryl hydrocarbon hydroxylases in lymphocytes is dependent on their activation. The tumor-promoting phorbol esters which induce blast formation and DNA synthesis in lymphocytes enable polycyclic aromatic hydrocarbons to induce aryl hydrocarbon hydroxylases. Melittin, the major constituent of bee venom, acts synergistically with these phorbol esters in enhancing both lymphocyte activation and hydroxylase synthesis. Since aryl hydrocarbon hydroxylases convert procarcinogens to carcinogens these results suggest that tumor promotion by phorbol esters may be associated with their ability to affect the induction of these enzymes. This hypothesis is supported by the finding that phorbol and phorbol esters which lack tumor-promoting activity fail to enhance induction of aryl hydrocarbon hydroxylases in lymphocytes. However mezerein, although rather ineffective in promoting tumors, activates lymphocytes and permits polycyclic aromatic hydrocarbons to induce their hydroxylases effectively.

Induction of aryl hydrocarbon hydroxylase in human peripheral blood lymphocytes by chrysene

Many of the polycyclic aromatic hydrocarbons (e.g., benzo[a]pyrene (B[a]P), benzanthracene (BA), 3-methylcholanthrene (3-MC)) are not only carcinogenic, but also induce AHH in human tissues. Recently, chrysene has been implicated as an etiologic determinant of chemical carcinogenesis. Here we describe the ability of chrysene to induce AHH in cultured human lymphocytes. Lymphocytes were obtained from 9 healthy subjects, divided into 2 sets, and cultured in duplicate, triplicate, or quadruplicate for 48 h. Chrysene (25 microM final concentration) in acetone was then added to the induced culture set and the control set received acetone alone. Lymphocytes were then cultured an additional 24 h before harvesting. AHH was quantitated by a fluorometric analysis of the phenolic metabolites produced by incubating the lymphocytes with B[a]P for 35 min. A significant increase in enzyme induction occurred in the chrysene-induced cultures compared with control (non-induced) cells (one-tailed student t-test; P less than 0.001). It was also observed that the interindividual variation in AHH inducibility seen with other PAHs is also observed with chrysene.

Aryl hydrocarbon hydroxylase in persons with lung or laryngeal cancer

To test whether the distribution of AHH inducibility is shifted toward the high end of the range in patients who had lung and laryngeal cancer, we measured this trait in 59 patients (32 lung and 27 laryngeal) who had resectable tumors and had been disease-free for a period of time. The advantage of selecting patients who were free of clinical disease was that measurement of their AHH inducibility should not have been affected by the disease state. Patient and control populations showed no difference in basal and induced AHH activity of AHH inducibility. The mean AHH inducibility in patients who had lung cancer was 3.20 +/- 0.20; in patients who had laryngeal cancer 2.96 +/- 0.18, and for all controls 3.29 +/- 0.04 (no significant difference at p = 0 05). Further analysis of the distribution of AHH inducibility in the patient group compared to controls showed no suggestion of a shift toward the higher end of the range in patients who had lung and laryngeal cancer.

Aryl hydrocarbon hydroxylase in asbestos workers

Aryl hydrocarbon hydroxylase (AHH) activity and inducibility were studied in the lymphoblasts of 47 asbestos workers and 31 control subjects. Mean inducibility (3-methylcholanthrene [MC]-or dibenz(a,h,)anthracene [DBA]-induced divided by basal enzyme activity) was greater in the occupationally exposed subjects than in the control subjects. The estimated estimated change in mean value (+/- SE) of MC inducibility was 0.88 +/- 0.21 (P less than 0.001), and that of DBA inducibility was 1.59 +/- 0.56 (P less than 0.01). Differences in inducibility values were particularly apparent in 12 pairs of spouses, in all of whom the inducibility values of the occupationally exposed subjects exceeded those of their spouses. The differences in inducibility of AHH resulted from increases in induced activity, not from any appreciable change in basal activities. They were independent of subject age, sex, smoking status, year of first exposure to asbestos, yield of lymphoblasts, or the rate of blastogenesis as measured by the incorporation of tritiated thymidine into nucleic acid. Increased AHH inducibility may bear some relation to the greatly increased risk of bronchogenic carcinoma in asbestos workers who smoke cigarettes.