Buthiobate: a potent inhibitor for yeast cytochrome P-450 catalyzing 14 alpha-demethylation of lanosterol

Buthiobate (S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbon-imidate), a fungicide, inhibited 14 alpha-demethylation of lanosterol catalyzed by a reconstituted enzyme system consisting of cytochrome P-450 (P-450(14)-DM) and NADPH-cytochrome P-450 reductase both purified from Saccharomyces cerevisiae. Concentration of buthiobate necessary for the 50% inhibition was 0.3 microM and this value was markedly lower than those of metyrapone and SKF-525A. Buthiobate bound stoichiometrically to P-450(14)-DM and induced Type II spectral change of the cytochrome. Buthiobate inhibited lanosterol-dependent enzymatic reduction of the cytochrome. These facts indicate that buthiobate binds to P-450(14)-DM with high affinity and acts as a potent inhibitor on the cytochrome.

[Effect of ara-A on the experimental herpes simplex virus encephalitis--pathology and fluctuation of the cerebrospinal fluid and serum antibody levels]

The effect of Ara-A treatment on the experimentally induced herpes simplex virus (HSV) encephalitis in rabbits was examined. Simultaneously practical value of enzyme-linked immunosorbent assay (ELISA) for rapid diagnosis was tested to find an early rise of antibody in cerebrospinal fluid (CSF) and serum in connection with an adoption of Ara-A administration. HSV encephalitis was produced by inoculation with type-1 HSV into the bilateral corneas of the eyes. A large amount of pus and typical neurological signs characteristic to encephalitis appeared after several days of infection. Ara-A therapy begun at the 3rd day of infection clearly increased the survival rate (90%) and improved the clinical signs, but the start of the drug at the 6th day could only increase the survival rate (60%) without cure of the clinical symptoms. ELISA could catch the early rise of IgG antibody in CSF from 3-4 days and in serum from 4-6 days after infection. Ara-A didn't interfere the antibody production. Viral antigens were found in the corneal epithelia and propria, neurons and Schwann's cells of trigeminal ganglia, neurons and glial cells of pons and cerebrum, especially in hippocampal nuclei. Typical Cowdry A and full type intranuclear inclusion bodies in the neurons were observed in the above tissues with infiltration of large amount of small round cells. In conclusion, Ara-A therapy in HSV encephalitis at the early stage of infection was quite effective for cure and the ELISA method is a useful tool for detection of early antibody rise in CSF and serum.

Altered cytochrome P-450 in a yeast mutant blocked in demethylating C-32 of lanosterol

Spectroscopic and enzymatic analysis of a Saccharomyces cerevisiae mutant in sterol biosynthesis (SG1 (erg 11); Trocha, P. J., Jasne, S. J., and Sprinson, D. B. (1977) Biochemistry 16, 4721-4726) that was blocked in demethylating C-32 of lanosterol (4,4,14 alpha-trimethyl-5 alpha-cholesta-8,24-dien-3 beta-ol) showed that it contained low levels of cytochromes P-450 and b5 compared to those present in the parent strain D-587, while NADPH-cytochrome c reductase activity was elevated. The fungicide buthiobate (S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate), which bound specifically to yeast cytochrome P450 responsible for demethylating C-32 of lanosterol and effected a Type II spectral change, did not react with SG1 cytochrome P-450. On the other hand, cholate-solubilized microsomes from SG1 formed a single precipitin line on Ouchterlony plates with antibodies raised against purified (Yoshida, Y., Aoyama, Y., Kumaoka, H., and Kubota, S. (1977) Biochem. Biophys. Res. Commun. 78, 1005-1010) yeast cytochrome P-450 specific for demethylating C-32 of lanosterol. Hence, mutant SG1 contained an altered protein which retained the antigenicity of cytochrome P-450 responsible for demethylating C-32 of lanosterol but lost its catalytic activity.

Characterization of a Saccharomyces cerevisiae mutant, N22, defective in ergosterol synthesis and preparation of [28-14C]ergosta-5,7-dien-3 beta-ol with the mutant

Analysis of sterols was made with a Saccharomyces cerevisiae mutant, N22, which was resistant to nystatin and defective in ergosterol synthesis, and with its parent strain, M10 (haploid type, methionineless, petite). The main sterol of M10 was ergosterol, whereas that of N22 was ergosta-5,7-dien-3 beta-ol. A small amount of ergosterol was found also in N22. This indicates that the delta 22-desaturation reaction in N22 is blocked, though not completely. Ergosta-5,8-dien-3 beta-ol, an unusual sterol, was detected in N22 but not in M10. Variations in the amounts and compositions of free and esterified sterols of both strains were examined during cultivation and the subsequent aerobic adaptation. The contents of free sterols, which were mostly composed of the respective main sterols of both strains, did not change markedly. In contrast, the contents and compositions of esterified sterols of both strains varied depending on the growth conditions. When the cells of both strains were aerobically adapted, the total contents of esterified sterols increase, as did, as the intermediate sterols. Upon aerobic adaptation in the presence of [methyl-14C]methionine, [28-14C]ergosta-5,7-dien-3 beta-ol accumulated markedly in N22 cells. Using this mutant, we devised a convenient method for preparation of the radioactive sterol in high yield.

Enzymatic treatment of formalin-fixed and paraffin-embedded specimens for detection of antigens of herpes simplex, varicella-zoster and human cytomegaloviruses

Attempts were made to detect antigens of herpes simplex (HS), varicella-zoster (VZ) and human cytomegalo (CM) viruses in pathological preparations made by formalin fixation and paraffin embedding as well as in infected culture cells by means of enzymatic treatment followed by indirect immunofluorescent staining, and the following results were obtained. 1) Specimens from autopsy cases, in which diagnosis was established by detection of viral antigens or virus isolation, showed specific antigens in specimens of various organs of all cases of HS (6 cases), VZ (3 cases) and CM (2 cases). In 17 other cases, which were suspected for those viral infections on the basis of ordinary light microscopic observation, also demonstrated respective viral antigens specifically, enabling differential diagnosis. In one case, HS antigen was detected in the esophagus and CM antigen in the liver, testifying occurrence of a double infection. 2) The time spun during which the specific antigens could be preserved was tested, and it was learned that preservation of stainable antigens was better in paraffin-embedded specimens than in specimens kept in formalin. It was possible to detect HS and VZ antigens in paraffin-embedded specimens prepared 20 and 18 years ago, respectively. 3) The optimal conditions of trypsin treatment varied depending upon the organ as well as upon each individual specimen, but a commonly recommendable procedure was found to by warming at 37 degrees C for 3 hours with 0.25% trypsin. A test with HS virus-infected Vero cells indicated that the effect of trypsin treatment was influenced by the concentration of formalin and the time of fixation.

L-Threonine dehydrogenase of chicken liver. Purification, characterization, and physiological significance

L-Threonine dehydrogenase (L-threonine:NAD+ oxidoreductase (EC 1.1.1.103) has been purified to apparent homogeneity from chicken liver mitochondria. The presence of 2-mercaptoethanol and glycerol is necessary for stabilizing the enzyme during purification and storage. The enzyme is a monomer and has Mr approximately equal to 88,000. The pH optimum is 8.6 to 8.7, and the isoelectric point of the enzyme is 5.9. The enzyme is specific for L-threonine and NAD+. The Km values for L-threonine and NAD+ are 8.4 and 0.98 mM, respectively. Kinetic studies indicate that the reaction proceeds through an Ordered Bi Bi mechanism where NAD+ is added first, followed by L-threonine. Chicken liver mitochondria contain aminoacetone synthase (acetyl-CoA:glycine C-acetyltransferase (EC 2.3.1.29)). The enzyme has been partially purified. In the presence of L-threonine dehydrogenase and aminoacetone synthase, L-threonine is cleaved to glycine and acetyl-CoA via 2-amino-3-oxobutyrate. The result suggests that L-threonine dehydrogenase and aminoacetone synthase have a physiological role in L-threonine metabolism in vertebrates.

Evidence for the presence of cytochrome P-450 functional in lanosterol 14 alpha-demethylation in microsomes of aerobically grown respiring yeast

Recent studies have shown that a cytochrome P-450 present in microsomes of semi-anaerobically grown cells of Saccharomyces cerevisiae is functional in the 14 alpha-demethylation of lanosterol (4,4,14 alpha-trimethyl-5 alpha-cholesta-8,24-dien-3 beta-ol), but the occurrence of the same cytochrome P-450 in microsomes of aerobically grown yeast cells has not yet been reported. In this study, the microsomal fraction from aerobically grown cells was found to catalyze the lanosterol demethylation in the presence of NADPH and O2 and that this activity was sensitive to CO. In Ouchterlony double diffusion test, antibodies to the yeast cytochrome P-450 formed a single precipitin line with the microsomal fraction as well as with the purified yeast cytochrome P-450 and the two precipitin lines fused with each other. Furthermore, the antibodies inhibited the lanosterol demethylation activity of the microsomal fraction from aerobically grown cells. The quadratic-derivative absorption spectrum of the microsomal fraction measured in the presence of both Na2S2O4 and CO showed an absorption band at 450 nm which is attributable to the reduced CO compound of cytochrome P-450. These facts led to the conclusion that cytochrome P-450 actually exists in aerobically grown yeast and participates in the lanosterol 14 alpha-demethylation which is essential for the ergosterol (5 alpha-ergosta-5,7,22-trien-3 beta-ol) biogenesis by yeast.

Consistent appearance of microtubules in cells productively infected with various strains of type 2 herpes simplex virus

Electron microscopic examination showed microtubular structures in FL cells infected with all 18 strains of HSV-2 examined, but not in cells infected with 9 strains of HSV-1. These structures were also detected in other cultured cells (Vero and Earle's L cells) infected with HSV-2, and also in vivo in cells, such as neuronal cells of the spinal ganglia and liver cells, of one-day-old suckling mice (DDD strain) infected with this type of virus. Thus the microtubules were consistently detected in cells productively infected with HSV-2. No other herpesviruses so far examined produced microtubular structures such as those observed in HSV-2 infected cells.

Effect of some dietary additions to either an arginine-devoid diet or a diet supplemented with orotic acid refed after starvation on liver lipid content during essential fatty acid deficiency in rats

Refeeding either an arginine-devoid diet or a 14% casein diet supplemented with 1% orotic acid for 7 days to starved rats caused an increase in liver lipid content which was prevented by the addition of adenine, allopurinol and safflower oil, but not guanine, cytosine, thymine and uracil. When rats were refed the arginine-devoid diet unsupplemented or supplemented with guanine, cytosine, thymine and uracil, their serum triglyceride and cholesterol decreased or tended to decrease as compared with those of rats refed the arginine-devoid diet supplemented with either adenine or allopurinol or rats refed the arginine-supplemented diet. Furthermore, triglyceride and cholesterol in serum of rats refed the arginine-devoid diet supplemented with either adenine or allopurinol increased as compared with those of rats refed the arginine-supplemented diet. The addition of either adenine or allopurinol to the arginine-devoid diet resulted in lowered lipid content in the liver as compared with the arginine-supplemented diet. Thus, when the arginine-devoid diet unsupplemented or supplemented with arginine, adenine and allopurinol was refed, liver lipid content was inversely related to the serum triglyceride level.

Involvement of cytochrome b5 and a cyanide-sensitive monooxygenase in the 4-demethylation of 4,4-dimethylzymosterol by yeast microsomes

According to Ohba et al. (Ohba, M., Sato, R., Yoshida, Y., Nishino, T. and Katsuki, H. (1978) Biochem. Biophys. Res. Commun. 85, 21-27), yeast microsomes catalyze the removal of three methyl groups attached to the C-4 and C-14 positions of [1,7,15,22,26,30-14C]lanosterol (4,4,14 alpha-trimethyl-5 alpha-cholesta-8,24-dien-3 beta-ol) in the presence of NADPH, NAD+ and molecular oxygen, concomitant with the liberation of 14CO2 derived from C-30 (one of the two methyl groups at the C-4 position). In this process the methyl group at the C-14 position is first removed in a cyanide-insensitive reaction and then the two methyl groups at the C-4 position are removed by a cyanide-sensitive enzyme system. In this study it was found that the 14CO2 formation from the 14C-labeled lanosterol was inhibited by antibodies to yeast cytochrome b5 and by palmitoyl-CoA, a substrate of the cytochrome b5-containing fatty acyl-CoA desaturase system of yeast microsomes. However, neither the antibodies nor palmitoyl-CoA inhibited the conversion of lanosterol to 4,4-dimethyl zymosterol (4,4-dimethyl-5 alpha-cholesta-8,24-dien-3 beta-ol). It is concluded that cytochrome b5 and a cyanide-sensitive enzyme are involved in the 4-demethylation of 4,4-dimethylzymosterol, but not the 14 alpha-demethylation of lanosterol, by yeast microsomes. It is suggested that a cyanide-sensitive enzyme acts as the terminal 4-demethylase and cytochrome b5 transfers reducing equivalents from NADPH to the terminal enzyme, as in the case of fatty acyl-CoA desaturation. The cyanide sensitivity of the 4-demethylation was, however, much greater than that of the desaturation.

Characteristics of osteogenic sarcoma of hamsters induced by BK virus

Two out of 9 weanling hamsters, treated with intravenous inoculation of highly concentrated human papovavirus BK, propagated in human embryonic kidney cells, developed osteogenic sarcomas of the costal cage and the mandibula. The sera of the tumor-bearing animals were positive for BK T-antigen and the successively transplanted tumors were positive for intranuclear T-antigen when tested with anti-SV40 T-antibody by immunofluorescence. The tumor tissue exhibited various stages of maturation, from areas showing immature sarcoma and angiomatous sarcoma to those of well-differentiated osteogenic sarcoma. Tumor histology was described in detail.

Fatal herpesvirus tamarinus infection in cotton-topped marmosets (Saguinus oedipus)

Fatal herpesvirus tamarinus infection was observed in cotton-topped marmosets (Saguinus oedipus) imported from South America via the United States on August 26, 1976. In addition to the lesions hitherto reported in herpesvirus tamarinus infection, severe degenerative and necrotic changes of ganglion cells were recognized with intranuclear inclusion bodies in the plexus of the digestive tract and the sympathetic nerves and their ganglions in the abdominal cavity. Inflammatory or regressive changes were also noted in the central nervous system. A large number of basophilic or eosinophilic intranuclear inclusion bodies frequently recognized in multinucleated giant cells were observed in various organs and tissues, and they showed different shapes at the electron microscopic level. Morphological findings indicated that herpesvirus tamarinus infection seemed to be similar to herpes simplex virus infection in man. The findings of the susceptibility of a variety of cell cultures to the virus isolate serologically identified as herpesvirus tamarinus and physicochemical characteristics of the virus isolate were in general agreement with the findings of herpesvirus tamarinus already reported by previous workers.

The distribution and localization of immunoglobulin in the gastric mucosa and gastric cancer

The distribution and localization of immunoglobulin in the gastric mucosa and gastric cancer were studied by means of immunofluorescence. In the lamina propria of the stomach, like the other parts of the gastrointestinal tract, IgA producing cells predominated, but their population density varied from case to case. The main portion of secretion of IgA in the stomach was deep foveolar epithelium. IgA containing epithelial cells in the stomach were much less than those in the intestine, but they increased with advancement of intestinal metaplasia. Some gastric cancer cells retained the ability of secretory component production and took up IgA in their cytoplasm.

Reactivation of herpes simplex virus (type 2) infection in trigeminal ganglia and oral lips with cyclophosphamide treatment

Age-dependent resistance in trigeminal nerve against type 2 herpes simplex virus infection through oral lips and reactivation of the latent virus infection with cyclophosphamide in the ganglion in correlation to theprimary infected part were studied in mice with immunofluorescent and histopathological methods. The mice acquired resistance in the nervous tissue after 8 weeks of age. The viral antigen appeared in all trigeminal ganglia immediately after infection, but not found at 4 weeks later. Reactivation of the latent infection was tried by using 8-week-old mice with cyclophosphamide treatment. Four to five times administration of the drug produced the leasions of herpes simplex virus infection in the ganglia and also in the primary infected areas, but viral antigen-bearing neurons in the ganglia were very few.