A comparative study revealed a similarity of catalytic, spectral, electrophoretic and immunochemical properties of microsomal cytochromes P-448 (Mr = 56,000) synthesized de novo in 3-methylcholanthrene- and beta-naphthoflavone-treated rats. The identity of peptide maps of microsomal and isolated cytochromes P-448 confirms the validity of the limited proteolysis method for identification of the homogeneity of microsomal hemoproteins and for a comparison of their structures. The data obtained provide a way for evaluation of similarity and differences in the structure and enzymatic activity of various monooxygenase forms without their preliminary isolation from the microsomal membrane.

The in vitro treatment of membranes isolated from different rat organs with a water-soluble synthetic antioxidant has resulted in the change of basal and stimulus-induced adenylate cyclase activity. It is believed that the antioxidant effect is realized rather at the level of signal transfer from activated receptor to adenylate cyclase than at the level of agonist-receptor interaction.

Metabolism of organophosphate pesticide trichlorometaphos-3 and its effect on liver monooxygenase system were studied in male rats of WAG strain, maintained on a diet deficient in lysine, methionine, threonine and vitamins A, C, E. Long-term deficiency of these essential nutrients led to inhibition of monooxygenase induction in acute intoxication with pesticide (150 mg/kg) and to restriction of the induction in chronic intoxication (3 mg/kg) within 3 and 6 months. As a result of the intoxication highly toxic intermediate 2,4,5-trichlorophenol was accumulated in liver tissue of the animals kept on the disbalanced diet. The data obtained suggest that the increased accumulation of 2,4,5-trichlorophenol in liver tissue, as a result of intoxication with trichlorometaphos-3, potentiated the effect of essential nutrients deficiency on stimulation of the monooxygenase system.

The effects of 5-iododeoxyuridine and 5-bromodeoxyuridine on differentiation of the cells of adenohypophysis rudiment from 3, 4, and 5 day old chick embryos were studied in the in vitro organ culture. On the 7th day of cultivation most explants from 3 and 4 day old embryos formed lentoids and individual cells with the lens phenotype among the adenohypophysis tissue. Alpha-, beta- and delta-crystalline were immunochemically detected in them. When cultivating explants from 5 day old embryos, no lentoids formed. But the immunochemical study of serial sections made it possible to detect in individual explants single alpha-crystalline-containing cells. There is a period in the development of chick adenohypophysis, which lasts five days of incubation and during which the adenohypophysis rudiment retained its capacity for lens differentiation despite the fact that it is already determined in the adenohypophysis direction.

The induction of the phenobarbital form of cytochrome P-450 by xenobiotics (phenobarbital, PB, hexachlorobenzene, HCB; hexachlorocyclohexane. HCCH, and aroclor 1016, Ar) was studied. It was demonstrated that administration of these compounds to animals is accompanied by an increase in the total cytochrome P-450, NADPH-cytochrome P-450 reductase, benzphetamine-N-demethylase and aldrin-epoxidase activities. Using monospecific antibodies against the cytochrome P-450 form isolated from PB-induced microsomes (PB-cytochrome P-450), a double immunodiffusion test revealed immunological identity of cytochrome P-450 forms induced by phenobarbital and other xenobiotics. The content of this form determined by rocket immunoelectrophoresis increased markedly and made up to 20-40% of the total cytochrome P-450 content. Antibodies against PB-cytochrome P-450 inhibited by 50-70% the benzphetamine-N-demethylase and aldrin-epoxidase activities, whereas the antibodies to methylcholanthrene-induced cytochrome P-450 were fairly ineffective. It was concluded that the chemically unrelated compounds induce in liver microsomes a cytochrome P-450 form, whose immunological properties and substrate specificity are close to the PB-form of cytochrome P-450.

The influence of 9 different carcinogens on gene amplification was studied in DM-15 Djungarian hamster cells. The effect was assessed by resistance to colchicine or methotrexate. It was found that tumour promotors (12-0-tetradecanoylphorbol-13-acetate (TPA), mezerein, tween-80) and some carcinogens possessing both initiating and promoting activity (20-methylcholanthrene, 7,12-dimethylbenz(a)antracene, aflatoxin B1) dramatically increased the number of colchicine and methotrexate-resistant cells. 4-0-methylTPA, a non-promoting analog of TPA, and alkylating carcinogens (ethylmethanesulphonate and nitrosomethylurea) did not induce gene amplification. It was suggested that the ability of carcinogens to induce gene amplification correlated with their ability to induce the second promotion stage.

Hepatocytes isolated from intact and phenobarbital-treated rats were separated by Ficoll discontinuous density gradient into five subpopulations. About 85% of the total cell number sedimented within the range of 1.044 to 1.126 g X cm-3. In intact rats, heavy hepatocytes contained about twice as much cytochrome P-450 and about 3 times as much cytochrome b5 as light cell population. Phenobarbital induced cytochrome P-450 in all subpopulations, with a more pronounced increase observed in light hepatocytes. On the contrary, maximum induction of cytochrome b5 was noted in heavy hepatocytes. The results demonstrate the absence of uniform distribution of cytochrome P-450 and b5 in hepatocyte subpopulations. The highest concentrations of both cytochromes are observed in heavy (centrolobular) hepatocytes.

The study of the inducing effect of phenobarbital on the activity of N-demethylase of aminopyrine in the rat liver microsomes revealed the correlation of the rate of enzymic reaction with the changes in the maximum binding of aminopyrine by cytochrome P-450 rather than with the content of hemoprotein itself. The comparison of the activity of N-demethylation of aminopyrine in control and phenobarbital-induced rats showed the quantitative correspondence of the yield of products of the reaction--formaldehyde in the liver microsomes and 4-aminoantipyrine in the urine samples. Self-induction of N-demethylating activity at repeated aminopyrine administration to rats and the dose dependence of this phenomenon were found.

Using immunochemical methods, the identity of cytochrome P-448 from liver microsomes of mice of "inducible" and "non-inducible" lines during induction by xenobiotics of MX-type (3-methylcholanthrene, 3,4-benzpyrene, 2,3,7,8-tetrachlorodibenzodioxin) was established. This hemoprotein form was shown to play a role in 3,4-benzpyrene metabolism. Monospecific antibodies to purified cytochromes P-448 and P-450 were obtained; the cytochrome P-448 content in microsomes was measured by rocket immunoelectrophoresis. The content of cytochrome P-448 in control and phenobarbital-induced microsomes makes up to 10-15% of the total hemoprotein content determinable from the CO-spectra. 3-Methylcholanthrene and 3,4-benzpyrene injected into "non-inducible" mice cause no increase in the content of this hemprotein form, whereas in mice induced with 2,3,7,8-tetrachlorodibenzodioxin it rises to 50%. Under these conditions, an almost 100% inhibition of 3,4-benzpyrene metabolism by antibodies to cytochrome P-448 is observed. Antibodies against cytochrome P-448 obtained from liver microsomes of 3-methylcholanthrene-induced mice cause a 90% inhibition of 3,4-benzpyrene in microsomes induced with 3-methylcholanthrene and 2,3,7,8-tetrachlorodibenzodioxin.

Organization of genes for colicin, immunity and lysis and regulation of their expression in colicinogenic plasmid ColD-CA23 were studied. The polypeptides synthesised in minicells carrying the ColD plasmid, its Tn5 mutants and the recombinant plasmids constructed by cloning the ColD EcoRV fragments on pBR325 were analysed. The position of the colicin gene promotor is established and direction of the gene transcription determined. The immunity gene was shown to be expressed independently of the gene coding for colicin and believed to have its own SOS-independent promotor. Treatment with mitomycin C of the ColD-carrying cells leads to induction of the synthesis both of colicin and of a 10 KD protein responsible for cell killing and lysis. This protein can be detected in a cultural medium under lysis. Plasmid mutations abolishing synthesis of the lysis protein prevent release of colicin. The colicin and lysis genes are arranged in an operon, the lysis gene being situated next to that of colicin. The ColD genetic map is suggested.

The influence of phenobarbital and ziksorin, liver monooxygenase inductors and the influence of inhibitor SKF 525-A on the toxic and therapeutic effects of vincristine were studied on CBA and C57Bl mice (with hemoblastosis La or intact). It was shown that acute toxicity and therapeutic activity of vincristine lowered on induction of the liver monooxygenases, whereas inhibition of this enzymatic system resulted in increased toxicity and lowered therapeutic activity of vincristine. The possible use of these results in treatment of cancer patients is discussed.

The effect of tumour promoter, 12-0-tetradecanoylphorbol-13-acetate (TPA), on the cloning efficiency of different clones of mouse tumour cells was studied in semi-solid medium. The clones varied in their response to TPA. Inhibition and inherited stimulation of colony-formation efficiency in semi-solid medium was revealed. One clone did not respond to TPA. The influence of environmental factors on the clone structure and tumour progression is discussed.

Injection of Wistar rats with five structurally different inducers of methylcholanthrene-type (polycyclic aromatic and heterocyclic hydrocarbons, chloro-derivatives of biphenyl and dibenzo-p-dioxin) results in the de novo synthesis of two P-448 hemoproteins (molecular weight 56 000 and 53 000 Da) differing in their functional and immunochemical properties in liver microsomes. A comparison of catalytic and immunochemical characteristics of five cytochrome P-448 forms (Mr = 56 000 Da) as well as the data from electrophoretic, proteolytic and inhibitory analyses revealed no differences in the preparations used, with the exception of 2,3,7,8-tetrachloro-dibenzo-p-dioxin-induced microsomes characterized by a low level of this cytochrome P-448 form and a higher molecular activity as compared with 3,4-benzpyrene and 7-ethoxyresorufin-induced microsomes. The experimental results do not confirm the hypothesis on the feasibility of induced synthesis of a variety of individual forms of monooxygenase that would correlate with the number of structural variants of inducers.

Native preparations of alpha, beta and gamma-interferons as well as recombinant beta-interferon and purified leukocyte alpha-interferon and purified leukocyte alpha-interferon exert antiviral and antiproliferative activity in CaOv cells. Native interferon preparations were shown to be more antiproliferative than purified interferons per unit of antiviral activity (with EMC as well as with less susceptible VSV used as test viruses). It was shown that level of 2'5' oligoadenylatesynthetase activity induction in general correlates with antiproliferative and pronounced antiviral activity of interferons, besides that, the earlier (by 11 hours) induction of the enzyme activity by beta-interferon correlates with more rapid expression of antiproliferative effects by this interferon in comparison with that of alpha-interferon, the latter inducing the peak of enzyme activity by 24 hours.

A new method for determination of the activity of phenanthrene-9,10-epoxidase, one of the monoxygenases of the system of drug metabolism, in rat liver microsomes was developed. The method includes the use of phenanthrene as substrate. The rate of the substrate epoxidation is measured with the help of HPLC reverse phase in accordance with the method of the internal standard (1-naphthol) by 9,10-dihydroxy-9,10-dihydrophenanthrene, a product of the intermediate epoxide hydrolysis. For rapid quantitative conversion of the formed 9,10-epoxy-9,10-dihydrophenanthrene endogenic epoxide hydrolase is used after selective termination of the monoxygenase reaction. The time of the assay by HPLC is 4.5 minutes. Phenobarbital is a more strong and selective inductor of this form of cytochrome P-450 than 3-methylcholanthrene. The simultaneous use of the two inductors does not result in additive increasing of the enzyme activity.

Karyological analysis was made of G-banded chromosomes in the cells of three independent CHO-K1 clones stably resistant to colchicine (Clch) selected for resistance to Clch at the concentration 0.1 mkg/ml (the first step of selection), and of one clone with higher but unstable level of resistance (2 mkg/ml--the second level of resistance). The results obtained revealed a morphological instability of the P-shoulder of chromosome Z6: more often an additional genetical material (AGM) at the distal end (Z6+), or rarely deletions (Z6-). In cells of the stable resistant clones of the first step of selection the length of AGM and their morphological structures were shown to be constant, but differed among the clones. In cells of the higher resistant unstable clone the length of AGM and their morphological structure were different in different cells within the clone. The AGMs in the Clch-resistant cells are discussed in terms of possible amplification of gene(s) responsible for the Clch resistance. In the cell population of clone selected for the resistance to 2 mkg/ml of Clch the frequency of rearranged chromosomes was shown to increase. In cells of all the analysed resistant clones the chromosome Z16 was found to lose its p-shoulder.