Effect of B-factor and its analogues on rifamycin biosynthesis in Nocardia sp

B-Factor, 3'-(1-butylphosphoryl)adenosine, which was isolated from yeast extract, is an inducer of rifamycin production in a rifamycin non-producing Nocardia mutant. Feeding of B-factor to the mutant culture demonstrated that the induction process was triggered during early stationary phase. Rifamycin production in the mutant was also induced by an exogenous supply of 3-amino-5-hydroxybenzoic acid, an intermediate of the antibiotic pathway, suggesting that a step upstream from the intermediate is regulated by B-factor. B-Factor analogues, i.e., alkylesters of 3'-AMP with alkyl side chains of C(2) approximately C(12) and n-butyl esters of 3'-GMP and 2'-AMP all showed the B-factor activity. Among these n-octyl ester of 3'-AMP showed the lowest effective concentration of approximately 3 x 10(-10) M. An intrinsic substance of the Nocardia sp. with potent B-factor activity and a UV absorption maximum at 260 nm was isolated from the cells of the parental strain.     

Inhibition of tumor cell invasion by ubenimex (bestatin) in vitro

We have investigated the effect of the immunomodulator ubenimex (bestatin) on tumor cell invasion of reconstituted basement membrane (Matrigel). The invasion of B16-BL6 melanoma cells and Lewis lung carcinoma (3LL) cells into Matrigel-coated filters was inhibited by the presence of bestatin in a concentration-dependent manner. The pretreatment of either tumor cells or Matrigel with bestatin, however, had little effect on the invasion of tumor cells. Since bestatin was found to inhibit amino-peptidase in addition to its immunomodulating activities, the inhibition of tumor invasion by bestatin is likely to be associated with the action as an enzyme inhibitor. Other aminopeptidase inhibitors, arphamenine B and amastatin A, could also inhibit tumor cell invasion into Matrigel. Bestatin inhibited hydrolyzing activities towards substrates of aminopeptidases in B16-BL6 melanoma cells. However, bestatin did not have any effect on the haptotactic migration and adhesion of tumor cells to the substrates. These results indicated that bestatin may inhibit tumor cell invasion through a mechanism involving its inhibitory action on aminopeptidases in tumor cells.     

Suppressive effects of phosphodiesterase type IV inhibitors on rat cultured microglial cells: comparison with other types of cAMP-elevating agents.

We investigated the effects of inhibitors of cAMP-specific phosphodiesterase type IV (PDE IV) on cultured rat microglial cells. Microglial cells expressed mRNA encoding PDE IV. Rolipram and RO-20-1724, specific inhibitors of PDE IV, elevated the intracellular cAMP level much higher than the other types of PDE inhibitors. cAMP in astrocytes but not in cerebrocortical neurons was similarly increased in response to treatment with PDE IV inhibitors examined. The PDE IV inhibitors, a beta-adrenergic agonist isoproterenol and an adenylyl cyclase stimulant forskolin suppressed the proliferation of microglial cells as revealed by PCNA-immunocytochemical staining. The PDE IV inhibitors suppressed release of TNF alpha and nitric oxide (NO) from lipopolysaccharide-activated microglial cells in pure culture, while they did not affect NO release from microglial cells in neuron-microglia coculture. The PDE IV inhibitors also suppressed superoxide anion production by phorbol ester-treated microglial cells. Isoproterenol and forskolin similarly suppressed the macrophage-like functions of activated microglial cells. However, the PDE IV inhibitors displayed novel effects distinct from those of isoproterenol, forskolin and 8Br-cAMP, regarding expression of mRNAs encoding PDE IV, metallothionein-1 and hemeoxigenase-1. The present data showed that the PDE IV inhibitors can be available to control microglial function and that their effects on glial cells should be taken into account when PDE IV inhibitors are used for treatment of brain diseases, such as multiple sclerosis.     

Experimental studies on microphthalmos formation in neonatal rats treated with monosodium-L-glutamate

Changes in the eyeball size were investigated in rats treated with monosodium glutamate (MSG) during the neonatal period. Correlations among ocular size and degenerative changes of the retina and optic nerve were also studied ophthalmoscopically and histologically. Rats received MSG 5 times, 2 times or once. In rats which received MSG 5 times, the administration was made at 1, 3, 5, 7 and 9 days of birth. In rats, which received MSG 2 times, the administration was made on 2 subsequent days (1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10, 12 and 13 or 15 and 16 postnatal days). In the group of rats, which received MSG once, the administration was made on each from the 1st to the 15th postnatal day. Microphthalmos formation was clearly observed only in rats with 5 times and 2 times (9 and 10 days) injection of MSG. In these rats, narrowing of retinal vessels, paleness and excavation of optic disks were observed ophthalmoscopically. Total liquefaction of the vitreous body were seen in the same groups. Histological examinations also revealed degeneration of the inner layers of the retina. These findings indicated that the administration of MSG at critical stages during postnatal development induces disturbances of eyeball growth. It was also suggested that the growth of the eyeball is closely associated with the postnatal development of the retina.     

Discontinuing chemoimmunotherapy in childhood acute lymphoblastic leukemia

We examined the results of discontinuing therapy in Japanese children with acute lymphoblastic leukemia. Of the 209 patients in chemoimmunotherapy study, 120 (57.4%) had all chemotherapy stopped after 3 years of complete remission, and 72 (34.4%) reached the point of discontinuing immunotherapy after 5 years of complete remission. Of the 120 children removed from chemotherapy, 14 (11.7%) have relapsed, mainly in the extramedullary sites (5 testis, 5 bone marrow, 3 central nervous system, 1 bone); relapses occurred 1-23 months after cessation of chemotherapy (median 11 months). Boys had a higher post-chemotherapy relapse rate than girls (0.21 vs. 0.08, P less than 0.05). None of the 72 children removed from immunotherapy have yet relapsed. Long-term remission and possibly cure can be expected in approximately one half of newly-diagnosed Japanese patients. Moreover, the active immunotherapy could be of benefit to elimination of bone marrow relapses after cessation of chemotherapy in children with acute lymphoblastic leukemia.     

Antitumor activity on line 10 hepatoma in strain 2 guinea pigs and pharmaceutical properties of quinonyl-MDP preparations

The pharmaceutical properties of quinonyl-MDP-66 were discussed with special reference to the stability of oil-in-water emulsion, distribution capacity into regional lymph nodes and tumor regressive activity. The oil-in-water emulsion of quinonyl-MDP-66, which was prepared by treatment of quinonyl-MDP-66 with squalane (25 x) and emulsified with aqueous solution of 5% HCO-60 and 5.6% d-mannitol, was kept in lyophylized state and used after reconstitution by the addition of water before use. The reconstituted suspension of quinonyl-MDP-66 in oil-in-water emulsion was stable for more than 24 hrs. The oil-in-water emulsion of quinonyl-MDP-66 as prepared above was effective for the distribution of quinonyl-MDP-66 into regional lymph node in rats and for the regression of line 10 hepatoma in strain 2 guinea pigs by intralesional injection.