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H Mitsuya

Publications and source records attributed to H Mitsuya.

At least 145 records · Page 8Linked to original sources
PubMed1992

A high proportion of early response genes are constitutively activated in T cells by HTLV-I.

Immortalization of T cells by HTLV-I is mediated by the X region of the virus and probably involves transactivation of cellular genes. We show that T cells transformed by HTLV-I constitutively express a high proportion of early response genes that are normally transiently induced following antigenic or mitogenic activation of T cells. Thus, HTLV-I-infected T cells display an 'early activation' phenotype that is distinct from the gene expression pattern of continuously dividing T cells. Ten early response genes representing a diverse array of functional categories were assayed. Four DNA-binding proteins/transcription factors including the p50 subunit of NF-kappa B were evaluated. A protein(s) encoded by the X region of HTLV-I appeared to contribute to up-regulated expression of most, if not all, of the early response genes. For those genes that could be assayed, increased transcriptional rates, but not substantial changes in mRNA half-life, were demonstrated in the presence of pX-encoded proteins, suggesting that the transcriptional transactivator, Tax, affects the induction or maintenance of transcription for these mitogen-inducible genes. Therefore, Tax may mimic or interact with a component(s) of the signal transduction pathway activated by antigen or mitogen treatment. These data demonstrate that early response genes, some of which probably play roles in initiating or maintaining cellular proliferation, are frequent targets of HTLV-I activation.

Blotting, Northern↗
PubMed1991

A ring-enlarged oxetanocin A analogue as an inhibitor of HIV infectivity.

Two ring-expanded analogues (compounds 2 and 3) of the anti-HIV fermentation product oxetanocin A (1) were synthesized from commercially available diacetone D-glucose. Antiviral testing against HIV in ATH8 cells revealed that the ring-expanded analogue 2 possessed a similar activity profile as oxetanocin A. Neither compound, however, was capable of providing full protection to the cells against HIV infection. The isomeric ring-expanded analogue 3 was totally devoid of anti-HIV activity. Molecular modeling suggested that while oxetanocin A and compounds 2 and 3 share a large common substructure with the potent anti-HIV drug, dideoxyadenosine (ddA), the extra hydroxymethyl substituent may contribute negatively to the binding of these molecules to a critical enzyme. The negative contribution may be less important in oxetanocin and isomer 2 than in isomer 3. From these studies it would appear that both oxetane and tetrahydrofuran rings are equivalent templates to support the adenine base in terms of anti-HIV activity.

Adenine↗
PubMed1991

Escherichia coli mediated biosynthesis and in vitro anti-HIV activity of lipophilic 6-halo-2',3'-dideoxypurine nucleosides.

A series of 6-substituted 2',3'-dideoxypurine ribofuranosides (ddP) was enzymatically synthesized with live E. coli in an effort to enhance the lipophilicity of this class of anti-human immunodeficiency virus (HIV) compounds and thereby facilitate drug delivery into the central nervous system. All 6-halo-substituted ddPs were substantially more lipophilic, as defined by their octanol-water partition coefficient (P), than their nonhalogenated congeners 2',3'-dideoxyinosine (ddI) or 2',3'-dideoxyguanosine (ddG). For this class of compounds, log P's ranged from +0.5 to -1.2 in the following order: 6-iodo, 2-amino-6-iodo greater than 6-bromo, 2-amino-6-bromo greater than 6-chloro, 2-amino-6-chloro greater than 6-fluoro, 2-amino-6-fluoro much greater than ddG greater than ddI. These compounds were evaluated in vitro for ability to suppress the infectivity, replication, and cytopathic effect of HIV. 2-Amino-6-fluoro-, 2-amino-6-chloro-, and 6-fluoro-ddP exhibited a potent activity against HIV comparable to that of ddI or ddG and completely blocked the infectivity of HIV without affecting the growth of target cells. The comparative order of in vitro anti-HIV activity was 2-amino-6-fluoro, 2-amino-6-chloro, 6-fluoro greater than 2-amino-6-bromo greater than 2-amino-6-iodo, 6-chloro greater than 6-bromo greater than 6-iodo. These compounds also exhibited potent in vitro activity against HIV-2 and 3'-azido-3'-deoxythymidine-resistant HIV-1 variants. All 2-amino-6-halo-ddPs and 6-halo-ddPs were substrates for adenosine deaminase (ADA) and were converted to ddG or ddI, respectively. In the presence of the potent ADA inhibitor 2'-deoxycoformycin, 6-halo-substituted ddPs failed to exert an in vitro antiretroviral effect. These dideoxypurine nucleoside analogues represent a new class of lipophilic prodrugs of ddG and ddI that possess the potential for more effective therapy of HIV-induced neurologic disorders.

Adenosine Deaminase↗
PubMed1991

Potential anti-AIDS drugs. Lipophilic, adenosine deaminase-activated prodrugs.

Selected acid-stable (2'-fluoro-2',3'-dideoxyarabinofuranosyl)adenine nucleosides containing methyl groups and other lipophilic functions at various positions in the adenine ring were prepared and evaluated as anti-HIV agents. The N6-methyl (1f), N6-benzoyl (1g), and 6-chloro (1i) analogues had modest activity, giving 30-50% protection to ATH8 cells infected with HIV. 2-Methyl (1d), 8-methyl (1h), and 2,N6-dimethyl (1e) substitution, as well as N1-oxide (21) formation, abolished the activity of the parent compound (1a). Several of these compounds, originally designed as agents for treating HIV in the central nervous system, were further investigated as substrates for adenosine deaminase (ADA). Kinetic experiments showed that ADA catalyzed the formation of the anti-HIV active inosine compound 1b from the N6-methyl analogue 1f in a quantitative manner. The anti-HIV activity of 1f and 1i was abolished when the ADA inhibitor, 2'-deoxycoformycin, was added to the test mixture. In contrast, the activity of 1f was significantly enhanced when ADA was added to the test system. These data indicate that 1f and 1i are prodrug forms of 1b in systems containing ADA.

Adenosine Deaminase↗
PubMed1991

In vitro inhibition of hepatitis B virus replication by 2',3'-dideoxyguanosine, 2',3'-dideoxyinosine, and 3'-azido-2',3'-dideoxythymidine in 2.2.15 (PR) cells.

Hep G2-derived hepatoblastoma cells (2.2.15), which actively produce hepatitis B virus (HBV), were cultured in the presence of 2',3'-dideoxyguanosine (ddG), 2',3'-dideoxyinosine, or 3'-azido-2',3'-dideoxythymidine (AZT). ddG was the most potent agent. It diminished viral replication by up to 95%, as assessed by the amount of episomal HBV DNA, without impairing cellular growth. AZT was the least effective against HBV. Northern blot analysis revealed no apparent difference in the pregenomic viral RNA profile, suggesting that these dideoxynucleosides suppress reverse transcription in the replicative cycle of HBV. The effect of varying the time of drug exposure showed that these agents can suppress HBV replication even when added late in culture. HBV replication in another 2.2.15 cell population of the same lineage was affected by ddG differently, which may enable the investigation of phenotypic or genetic alterations during culture. The present data suggest that some 2',3'-dideoxynucleosides can exert a potent antiviral activity against HBV in vitro, at least under certain circumstances, although the data do not prove that any of these agents have utility in patients with hepatitis.

Blotting, Southern↗
PubMed1991

Targeted therapy of human immunodeficiency virus-related disease.

Since the discovery of human immunodeficiency virus (HIV) as a pathogenic retrovirus linked to acquired immunodeficiency syndrome (AIDS), a number of potentially useful strategies for antiretroviral therapy of AIDS and its related diseases have emerged. One such strategy involves use of the broad family of 2',3'-dideoxynucleosides, to which 3'-azido-2',3'-dideoxythymidine (AZT) belongs. AZT has been shown to reduce the replication of HIV in vivo and to confer significant clinical benefits in patients in both early and advanced stages of infection. Other members of the family, 2',3'-dideoxycytidine (ddC), 2',3'-dideoxyinosine (ddI), and 2',3'-didehydro-2',3'-dideoxythymidine (d4T), have also been reported to be active against HIV in short-term clinical trials. The armamentarium of antiretroviral agents is rapidly growing. Various nonnucleoside agents have recently been identified to be active against HIV in vitro. HIV-1 protease inhibitors are notable as possible new therapies for HIV-1-related diseases. However, we have faced several new challenges in the antiretroviral therapy in AIDS. These include long-term drug-related toxicities; emergence of drug-resistant HIV variants; and development of various cancers, particularly as effective therapies prolong survival. Progress in understanding structure-activity relations and clinical effectiveness will continue with dideoxynucleoside analogs. However, it seems certain that a variety of nonnucleoside analogs affecting multiple steps in viral replication will become available before long, and combination therapies using multiple antiretroviral drugs will be available. Such therapies will exert major effects against the moribidity and mortality caused by HIV.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Targeted and highly efficient gene transfer into CD4+ cells by a recombinant human immunodeficiency virus retroviral vector.

We have established a recombinant HIV gene transfer system based on transient expression of the HIV packaging functions and a recombinant vector genome in monkey kidney Cos cells. The recombinant HIV retroviral vector introduced the neoR gene into CD4+ cells with high efficiency, comparable to that achieved with the highest titer amphotropic murine recombinant retrovirus. Vector preparations were devoid of replication competent, infectious HIV. Gene transfer was dependent on CD4 expression, as shown by expression of the CD4 gene in HeLa cells, and could be inhibited by soluble CD4. This specific and efficient gene transfer system may be useful for development of gene therapy for which T cells are the desired targets.

CD4 Antigens↗
PubMed1991

Synthesis and structure-activity relationships of 2',3'-dideoxypurine nucleosides as potential antiretroviral agents.

In order to study the structure-activity relationships of 2',3'-dideoxypurine nucleosides as potential anti-retroviral agents, various purine derivatives have been synthesized and tested against rous sarcoma virus (RSV) in chick embryo fibroblast (CEF) cells, and against human immunodeficiency virus (HIV) in human CD4+ T cells (ATH8). Some of the new purine derivatives found to be significant antiretroviral activities. And the correlations of activity between anti-RSV and anti-HIV have shown fairly good values so far.

Animals↗
PubMed1991

Inhibitors of IMP dehydrogenase stimulate the phosphorylation of the anti-human immunodeficiency virus nucleosides 2',3'-dideoxyadenosine and 2',3'-dideoxyinosine.

2',3'-Dideoxyadenosine (ddAdo) and its deamination product 2',3'-dideoxyinosine (ddIno) (didanosine) inhibit the replication and infectivity of the human immunodeficiency virus (HIV) in a number of in vitro assay systems. Early clinical studies (phase I) have indicated a role for ddIno in the treatment of patients with severe HIV infection. In the present in vitro study, the formation in human T cells (MOLT-4, ATH8, and CCRF-CEM) of the pharmacologically active metabolite of ddIno and ddAdo, 2',3'-dideoxyadenosine-5'-triphosphate (ddATP), was found to be stimulated 2-4-fold by appropriate concentrations of inosinate dehydrogenase (IMPD) inhibitors such as ribavirin, tiazofurin, and mycophenolic acid. Concomitant with this increase in ddATP formation from ddIno was an increase in anti-HIV activity of this agent when it was combined with ribavirin in the ATH8 cell assay system and with tiazofurin in the MOLT-4 assay system. No change was noted in the intracellular concentration of the corresponding physiological deoxynucleoside-5'-triphosphate, dATP; positive correlation was observed, however, between the increase in ddATP formation from ddIno and the increase in intracellular IMP occurring as a consequence of IMPD inhibition. The results support the hypothesis that the stimulation of ddATP formation seen when ddIno is combined with ribavirin or other IMPD inhibitors is a consequence of an increased concentration of IMP, the major phosphate donor for the initial phosphorylation step in the anabolism of ddIno to ddATP, i.e., ddIno----ddIMP.

Antiviral Agents↗
PubMed1991

Hematologic effects of AIDS therapies.

Hematologic abnormalities remain an important feature of HIV infection, and they often limit the therapy of this disorder. This is currently a field of intense research, and some progress has already been made. The current development of newer, less myelosuppressive therapies for HIV infection is encouraging. In addition, as more is learned about the biochemistry, molecular biology, and pathophysiology of HIV and its effects upon its host, more effective, HIV-specific, and less toxic therapies may be developed. Finally, the use of various cytokines to ameliorate toxicities and possibly stimulate the functioning of myeloid cells is a promising area of research and should be pursued further. However, in spite of these efforts, much more needs to be done. In particular, therapy of HIV-associated lymphoma, which is likely to be increasingly observed as AIDS patients live longer, is often entirely unsatisfactory, in part because patients cannot tolerate the hematologic toxicity of the regimens employed. As in the general field of oncology, hematologic toxicities in AIDS remains a major limitation of therapy, and advances in this area have the potential to markedly improve both survival and quality of life.

Acquired Immunodeficiency Syndrome↗
PubMed1990

NIH conference. Antiretroviral therapy in AIDS.

OBJECTIVE: To review recent developments of antiretroviral therapy for the acquired immunodeficiency syndrome (AIDS) and related disorders. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION: An edited and updated summary of a Clinical Staff Conference held 26 October 1988 at the National Institutes of Health. The speakers discussed their own work as well as related work from other groups. DATA SYNTHESIS: The discovery that human immunodeficiency virus (HIV) causes AIDS has permitted the development of rational antiviral therapy for this disease. Various steps in the replicative cycle of HIV can be targeted for intervention. More basic research into the life cycle of HIV is therefore likely to yield new therapeutic approaches. In 1985, nucleoside analogues called dideoxynucleosides were discovered to be potent inhibitors of HIV replication in vitro. Dideoxynucleosides selectively inhibit HIV reverse transcriptase after they are phosphorylated intracellularly to 5'-triphosphates. One dideoxynucleoside, 3'-azido-2',3'-dideoxythymidine (AZT or zidovudine) has been found to prolong the life of patients with AIDS. This drug can partially reverse HIV dementia and decrease short-term progression to AIDS; it has been approved for treating HIV-infected patients with fewer than 500 CD4+ cells/mm3. AZT is only a first step in developing new therapy for AIDS. Its use is associated with toxicities, particularly bone marrow suppression. Several groups have reported the development of AZT-resistant strains of HIV. Other dideoxynucleosides whose toxicity profiles differ from that of AZT have also shown activity against HIV in early clinical studies. Large-scale, randomized trials of these drugs are now under way. Studies have shown that the binding of HIV to CD4 may be blocked by genetically engineered forms of CD4 and that HIV protease may be inhibited by substrate analogues. Protease inhibitors are an excellent area for further study in patients. Antisense oligonucleotide therapy may target the regulatory genes of HIV and is also being considered. CONCLUSION: With these advances, AIDS is gradually changing from an imminently fatal disease to one that can be managed with the judicious use of drugs and biologics. Progress against AIDS will continue, provided that researchers adhere to the principles of controlled trials.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Inhibitors of IMP dehydrogenase stimulate the phosphorylation of the antiviral nucleoside 2' ,3'-dideoxyguanosine.

The inosinate dehydrogenase (IMPD) inhibitors ribavirin, tiazofurin and mycophenolic acid were found to stimulate by as much as 20-fold the anabolism of the anti-HIV agent 2' ,3'dideoxyguanosine to its 5'-diphosphate (ddGDP) in a human T-cell culture system (Molt-4 cells). Stimulation of the further conversion to ddGTP (the active form of the drug) was lesser in magnitude but still highly significant (up to 4-fold at appropriate concentrations of ribavirin or tiazofurin). In parallel with these increases, the inhibitors also produced increases of up to 35-fold in IMP levels. These results support the proposal that the initial phosphorylation of ddGuo is catalyzed by a phosphotransferase (5'-nucleotidase) which utilizes IMP as its phosphate donor (Johnson and Fridland, [1989] Molec. Pharmacol. 36, 291-295). Concomitant with this increase in 5'-phosphorylation of ddGuo, an increase in its anti-HIV activity of up to 6.5-fold was observed when this agent was combined with ribavirin (5 microM) in the H9 [corrected] cell assay system.

Antiviral Agents↗
PubMed1990

Molecular targets for AIDS therapy.

The development of antiretroviral therapy against acquired immunodeficiency syndrome (AIDS) has been an intense research effort since the discovery of the causative agent, human immunodeficiency virus (HIV). A large array of drugs and biologic substances can inhibit HIV replication in vitro. Nucleoside analogs--particularly those belonging to the dideoxynucleoside family--can inhibit reverse transcriptase after anabolic phosphorylation. 3'-Azido-2',3'-dideoxythymidine (AZT) was the first such drug tested in individuals with AIDS, and considerable knowledge of structure-activity relations has emerged for this class of drugs. However, virtually every step in the replication of HIV could serve as a target for a new therapeutic intervention. In the future, non-nucleoside-type drugs will likely become more important in the experimental therapy of AIDS, and antiretroviral therapy will exert major effects against the morbidity and mortality caused by HIV.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Long-term toxicity/activity profile of 2',3'-dideoxyinosine in AIDS or AIDS-related complex.

To evaluate the long-term toxicity and activity profile of 2',3'-dideoxyinosine (ddI), a potent inhibitor of human immunodeficiency virus (HIV) replication, in vitro. 58 patients with AIDS or AIDS-related complex were studied with additional reference to the effect of previous treatment with zidovudine, and the effect of ddI on HIV-induced cognitive dysfunction. Doses above 9.6 mg/kg per day of ddI were frequently associated with toxicity (peripheral neuropathy, pancreatitis, or hepatitis). Doses of 9.6 mg/kg per day or below were well tolerated for up to 21 months. A subset of patients receiving 3.2-9.6 mg/kg per day of ddI had long-term immunological improvement and reduction of serum HIV p24 antigen. Immunological changes were especially seen in patients who had little previous zidovudine therapy. 5 patients with HIV-induced cognitive impairment improved with ddI. Thus, ddI may have anti-HIV activity at doses which are tolerated for long-term therapy, although pancreatitis could be a life-threatening complication.

AIDS Dementia Complex↗
PubMed1990

Expression of a zinc finger gene in HTLV-I- and HTLV-II-transformed cells.

Gene products encoded by the human T cell leukemia virus (HTLV) types I and II mediate transformation by the transactivation of cellular genes necessary for proliferation, probably including transcriptional regulatory factors. By searching for factors that may control proliferation, a zinc finger gene (225) was identified that was constitutively expressed in all HTLV-I- or HTLV-II-transformed cell lines examined, whereas in normal T cells it was only transiently expressed after mitogenic stimulation. The 225 gene was also constitutively expressed in two HTLV-I-transformed helper T cell clones, but not in the parental cell lines. Thus this putative cellular transcriptional factor, which was abnormally expressed in retrovirus-infected cells, may have a role in transformation.

Amino Acid Sequence↗