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H Mitsuya

Publications and source records attributed to H Mitsuya.

At least 73 records · Page 4Linked to original sources
PubMed1998

Expression of Bcl-2 family of proteins in fresh myeloma cells.

Members of the Bcl-2 family of proteins, Bcl-2, Bcl-X(L), Bcl-Xs and Bax, are considered to play important roles in the regulation of apoptosis and drug resistance. To understand the significance of these proteins in fresh human myeloma cells, expression of Bcl-2 family of proteins was analyzed by Western blotting in 17 cases with multiple myeloma (MM) and three cases with plasma cell leukemia (PCL). Bcl-2 and Bcl-X(L) were found in 12 and nine samples, respectively. All PCL cases showed co-expression of Bcl-2 and Bcl-X(L). Analysis of MM cases showed that Bcl-2 was preferentially expressed in samples from cases with early clinical stage while Bcl-X(L) tended to be expressed in samples from cases at advanced clinical stage. Bcl-X(L) was significantly expressed in tumor cells from cases with extramedullar lesions. There was no correlation between the expression levels of Bcl-2 or Bcl-X(L) and preceding chemotherapy. Expression of Bax was found in only one patient who had pleural effusion caused by invasion of myeloma cells and a high serum LDH level. Survival analysis revealed that there was no statistical significance in expression of Bcl-2 or Bcl-X(L) although Bcl-X(L) tended to be expressed in cases with poor prognosis. These findings indicate that expression of Bcl-2 family of proteins is heterogeneously regulated in fresh myeloma cells. Expression of Bcl-X(L) and Bcl-2 may correlate with extramedullar invasion and early stage of the disease, respectively. Absence of Bax in myeloma cells may contribute to low sensitivity of myeloma cells to anti-cancer agents since Bax is reported to mediate cytotoxicity of some anti-cancer drugs.

Adult↗
PubMed1998

Altered drug sensitivity, fitness, and evolution of human immunodeficiency virus type 1 with pol gene mutations conferring multi-dideoxynucleoside resistance.

Investigations were done to determine whether the replication kinetics of human immunodeficiency virus (HIV)-1 were altered when the virus acquired a set or subsets of five mutations (A62V, V75I, F77L, F116Y, and Q151M) in the pol gene conferring resistance to multiple dideoxynucleosides. In the absence of drugs, the replication rate of all infectious clones generated was comparable to that of wild type HIV-1. However, in the presence of zidovudine or didanosine, the comparative order for replication was HIV-1(62/75/77/116/151) > HIV-1(77/116/151) > HIV-1(75/77/116/151) approximately HIV-1(151), whereas that for drug resistance was HIV-1(75/77/116/151) > HIV-1(62/75/77/116/151) > or = HIV-1(77/116/151) > HIV-1(151). The virologic features of these infectious mutants suggest that HIV-1 develops drug resistance through one or more mutations, which, however, sacrifice replicative capability; then it finally acquires optimal replication competence by additional mutations when the multi-dideoxynucleoside-resistant mutant emerges.

Animals↗
PubMed1998

Emergence of multi-dideoxynucleoside-resistant human immunodeficiency virus type 1 variants, viral sequence variation, and disease progression in patients receiving antiretroviral chemotherapy.

A set of five reverse transcriptase mutations, which include Q151M, is known to confer multi-dideoxynucleoside resistance (MDR) in human immunodeficiency virus type 1 (HIV-1). MDR mutations were found in 6 (17%) HIV-1 isolates from 36 patients, most of whom were receiving long-term combination therapy. Q151M was among the first of the substitutions to appear. Additional substitutions were observed, although none were common among all 6 patients. Certain zidovudine-related mutations were not observed together with the MDR mutations, indicating possible enzymatic constraint. During chemotherapy, the HIV-1 RNA levels in the 6 patients initially decreased and then rose. Initially, CD4 cell counts also responded favorably but were near or below baseline beyond 40 months of therapy. Such loss of clinical benefits appeared to coincide with the appearance of the MDR mutations. A common background genotype was not observed among HIV-1 isolates with or without MDR.

Adult↗
PubMed1998

Pharmacokinetics of the protease inhibitor KNI-272 in plasma and cerebrospinal fluid in nonhuman primates after intravenous dosing and in human immunodeficiency virus-infected children after intravenous and oral dosing.

KNI-272 is a human immunodeficiency virus (HIV) protease inhibitor with potent activity in vitro. We studied the pharmacokinetics of KNI-272 in the plasma and cerebrospinal fluid (CSF) of a nonhuman primate model and after intravenous and oral administration to children with HIV infection. Plasma and CSF were sampled over 24 h after the administration of an intravenous dose of 50 mg of KNI-272 per kg of body weight (approximately 1,000 mg/m2) to three nonhuman primates. The pharmacokinetics of KNI-272 were also studied in 18 children (9 males and 9 females; median age, 9.4 years) enrolled in a phase I trial of four dose levels of KNI-272 (100, 200, 330, and 500 mg/m2 per dose given four times daily). The plasma concentration-time profile of KNI-272 in the nonhuman primate model was characterized by considerable interanimal variability and rapid elimination (clearance, 2.5 liters/h/kg; terminal half-life, 0.54 h). The level of drug exposure achieved in CSF, as measured by the area under the KNI-272 concentration-time curve, was only 1% of that achieved in plasma. The pharmacokinetics of KNI-272 in children were characterized by rapid elimination (clearance, 276 ml/min/m2; terminal half-life, 0.44 h), limited (12%) and apparently saturable bioavailability, and limited distribution (volume of distribution at steady state, 0.11 liter/kg). The concentrations in plasma were maintained above a concentration that is active in vitro for less than half of the 6-h dosing interval. There was no significant increase in CD4 cell counts or decrease in p24 antigen or HIV RNA levels. The pharmacokinetic profile of KNI-272 may limit the drug's efficacy in vivo. It appears that KNI-272 will play a limited role in the treatment of HIV-infected children.

Administration, Oral↗
PubMed1998

The impact of multidideoxynucleoside resistance-conferring mutations in human immunodeficiency virus type 1 reverse transcriptase on polymerase fidelity and error specificity.

Variants of human immunodeficiency virus type 1 (HIV-1) that are highly resistant to a number of nucleoside analog drugs have been shown to develop in some patients receiving 2',3'-dideoxy-3'-azidothymidine therapy in combination with 2',3'-dideoxycytidine or 2',3'-dideoxyinosine. The appearance, in the reverse transcriptase (RT), of the Q151M mutation in such variants precedes the sequential appearance of three or four additional mutations, resulting in a highly resistant virus. Three of the affected residues are proposed to lie in the vicinity of the template-primer in the three-dimensional structure of the HIV-1 RT-double-stranded DNA complex. The amino acid residue Q151 is thought to be very near the templating base. The nucleoside analog resistance mutations in the beta9-beta10 (M184V) and the beta5a (E89G) strands of HIV-1 RT were previously shown to increase the fidelity of deoxynucleoside triphosphate insertion. Therefore, we have examined wild-type HIV-1BH10 RT and two nucleoside analog-resistant variants, the Q151M and A62V/V75I/F77L/F116Y/Q151M (VILYM) RTs, for their overall forward mutation rates in an M13 gapped-duplex assay that utilizes lacZ alpha as a reporter. The overall error rates for the wild-type, the Q151M, and the VILYM RTs were 4.5 x 10(-5), 4.0 x 10(-5), and 2.3 x 10(-5) per nucleotide, respectively. Although the mutant RTs displayed minimal decreases in the overall error rates compared to wild-type RT, the error specificities of both mutant RTs were altered. The Q151M RT mutant generated new hot spots, which were not observed for wild-type HIV-1 RT previously. The VILYM RT showed a marked reduction in error rate at two of the predominant mutational hot spots that have been observed for wild-type HIV-1 RT.

Anti-HIV Agents↗
PubMed1998

[Anti-HIV drugs and drug delivery system].

A number of candidate drugs for therapy of HIV-1 infection which show significant activity against the virus in vitro were reported; however, many of them have been dropped from drug development due to (i) insufficient intracellular activation in certain human target cells (particularly in case of nucleoside reverse transcriptase inhibitors), (ii) poor pharmacokinetic profiles, or (iii) intolerable in vitro and/or in vivo toxicities. To circumvent some of these problems, certain drug delivery systems have been applied and several candidate drugs including two novel nucleoside reverse transcriptase inhibitors, abacavir and adefovir, have acquired favorable properties in the clinical setting. This paper reviews several avenues for developing prodrugs of anti-HIV-1 agents to overcome their inherent limitations.

Acquired Immunodeficiency Syndrome↗
PubMed1998

[Two cases of adrenal myelolipoma diagnosed by ultrasonically guided percutaneous biopsy].

We report 2 cases of adrenal myelolipoma which were diagnosed definitively by ultrasonically guided percutaneous biopsy to waive surgery. In case 1, a 39-year-old man presented with abdominal pain. A right adrenal mass was detected by abdominal ultrasonography. In case 2, a 64-year-old man presented with nocturia. A space-occupying lesion above the left kidney was detected by excretory pyelography. Both cases were suspected of adrenal myelolipoma by ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). The tumor size was 4 x 4 x 3 cm and 5 x 4.5 x 4 cm in cases land 2, respectively. In both cases percutaneous needle biopsy using ultrasonically guided puncture was performed. Histology showed a complex of hematopoietic and adipose tissues, corresponding to adrenal myelolipoma. The course has been uneventful without surgery for 58 months and 24 months, respectively. Percutaneous adrenal biopsy was useful to establish the definitive diagnosis and to select treatment options.

Adrenal Gland Neoplasms↗
PubMed1997

Phosphodiester amidates of unsaturated nucleoside analogues: synthesis and anti-HIV activity.

The effect of introduction of a lipophilic phosphodiester amidate moiety on the HIV activity of inactive unsaturated nucleoside analogues was investigated. Phosphodiester alaninates 5a, 5b, and 6 derived from unsaturated nucleoside analogues 3b, 3c, and 4a were synthesized and investigated as inhibitors of cytopathic effect and replication of HIV-1 in ATH-8 cells. Compound 5a is an inhibitor of HIV-1 whereas analogue 6 is inactive with cytotoxicity appearing above 10 microM and 5b is both inactive and nontoxic. Alkaline or enzymic hydrolysis of 5a gave phosphomonoester alaninate 14, a putative product of intracellular metabolism. Compound 14 as well as adenallene derivative 15c were devoid of anti-HIV activity, and they also failed to inhibit HIV reverse transcriptase. A new regioselective method for preparation of (Z)-4-(benzoyloxy)-1-hydroxy-2-butene, 7, a key intermediate for the synthesis of unsaturated nucleoside analogues of cis configuration such as 3a, 3b, and 3c, is also described.

Animals↗
PubMed1997

Comparative enzymatic study of HIV-1 reverse transcriptase resistant to 2',3'-dideoxynucleotide analogs using the single-nucleotide incorporation assay.

Employing the single-nucleotide incorporation assay using a heteropolymeric RNA template and DNA primers, we defined enzymatic profiles of recombinant human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) containing a set of five mutations [A62V, V75I, F77L, F116Y, and Q151M] which confers resistance to multiple 2',3'-dideoxynucleosides (ddNs) on HIV-1. RTs containing other drug-resistance-associated mutations were also examined. The K(m) for dNTPs, the kcat, and the kcat/ K(m) ratios of mutant RTs were all comparable to those of wild-type RT (RTwt). The processive primer extension activity of mutant RTs was also comparable to that of RTwt as examined in the presence of saturating concentrations of dNTPs and heparin. Determination of the Ki values toward 5'-triphosphates (TP) of various ddNs [3'-azido-2',3'-dideoxythymidine (AZT), 2',3'-didehydro-2',3'-dideoxythymidine (D4T), 2',3'-dideoxycytidine (ddC), (-)-beta-L-2',3'-dideoxy-3'-thiacytidine (3TC), (-)-beta-L-2',3'-dideoxy-5-fluorocytidine (FddC), 2',3'-dideoxyadenosine (ddA), and 2'-beta-fluoro-2',3'-dideoxyadenosine (FddA)] and 9-(2-phosphonylmethoxyethyl)adenine diphosphate (PMEApp) revealed that RTA62V/V75I/F77L/F116Y/Q151M was insensitive to ddATP, AZTTP, D4TTP, FddATP, and ddCTP, but was sensitive to PMEApp, 3TCTP, and FddCTP. RTK65R was less sensitive to ddATP, FddATP, PMEApp, ddCTP, and 3TCTP, while RTM184V was less sensitive only to 3TCTP and ddCTP. The determination of Ki(ddNTP)/K(m)(dNTP) ratios showed that AZTTP, D4TTP, and ddCTP are, as substrates, as efficient for RTwt as their corresponding dNTPs, that ddATP, PMEApp, and 3TCTP are moderately efficient substrates for RTwt, and that FddATP is the least efficient substrate among ddNTPs examined. The observed cross-resistance of HIV-1 RT to various ddNTPs should reflect the alteration of RT's substrate recognition and should provide insights into the molecular mechanism of RT discrimination of ddNTPs from natural substrates.

Anti-HIV Agents↗
PubMed1997

HIV-1 protease does not play a critical role in the early stages of HIV-1 infection.

We asked whether human immunodeficiency virus type 1 (HIV-1) protease plays a major role in the early stages of infection (i.e. from viral entry to reverse transcription) by using various protease inhibitors (saquinavir, ritonavir, and KNI-272). When assessed in the two-day multinuclear activation of a galactosidase indicator (MAGI) assay, involving a single cycle of HIV-1 replication, all protease inhibitors failed to block infection of HeLa-CD4-LTR-beta-gal cells by HIV-1, while reverse transcriptase (RT) inhibitors (AZT and ddI) completely blocked the infection. Moreover, when HIV-1 proviral DNA synthesis was examined by polymerase chain reaction in HeLa-CD4-LTR-beta-gal cells exposed to HIV-1 and cultured in the presence of protease inhibitors, a significant amount of proviral DNA was detected, while no proviral DNA synthesis was detected when the cells were cultured in the presence of RT inhibitors. Protease inhibitors also failed to block chloramphenicol acetyltransferase (CAT) expression in HLCD4-CAT cells exposed to HIV-1, while RT inhibitors completely suppressed CAT expression. These results strongly suggest, contrary to a previous report by Nagy et al. (1994), that HIV-1 protease does not play a major role in the early stages of infection.

Chloramphenicol O-Acetyltransferase↗
PubMed1997

HIV-1 acquires resistance to two classes of antiviral drugs through homologous recombination.

Genetic recombination contributes to the genomic heterogeneity of human immunodeficiency virus type 1 (HIV-1). In the present study, we demonstrate that HIV-1 readily develops resistance to two classes of anti-HIV-1 drugs through in vitro genetic recombination involving large segments of the viral genome. Co-transfection of COS-7 cells with an HIV-1 plasmid (pSUM13) carrying five mutations in the reverse transcriptase (RT)-encoding region (A62V, V75I, F77L, F116Y, Q151M), conferring resistance to multiple dideoxynucleoside analogs (ddNs), and another HIV-1 plasmid (pSUM431) carrying five mutations in the protease-encoding region (V321, L33F, K451, 184V, L89M), conferring resistance to protease inhibitors such as KNI-272, readily produced HIV-1 carrying both sets of mutations when propagated in MT-2 cells in the presence of azidothymidine (AZT) and KNI-272. The resultant HIV-1 variant was highly resistant to both ddNs and KNI-272. Co-infection of MT-2 cells with HIV-1SUM13 carrying the RT mutations and HIV-1SUM431 carrying the mutations in the protease also generated HIV-1 with both sets of mutations when cultured with AZT and KNI-272. We also report here that the problematic artifactual recombination occurring during genetic analyses of heterogeneous nucleic acid sequences using polymerase chain reaction can be successfully obviated.

Animals↗
PubMed1997

Effect of combination therapy with zidovudine and didanosine on neuropsychological functioning in patients with symptomatic HIV disease: a comparison of simultaneous and alternating regimens.

OBJECTIVE: To evaluate the effects of treatment with alternating and simultaneous regimens of zidovudine and didanosine on neuropsychological function in patients with symptomatic HIV-1 disease, focusing on patients with possible HIV-1-associated central nervous system (CNS) compromise at entry. DESIGN: Randomized non-blinded clinical trial. SETTING: Government medical research center. PATIENTS: Thirty-eight patients with symptomatic HIV-1 disease, of whom 21 had evidence of CNS compromise at entry. RESULTS: After 12 weeks of therapy, overall significant improvements in memory (P < 0.01) and focused attention (P < 0.001) were seen on both regimens. These gains, however, were largely limited to those patients with HIV-1-associated CNS compromise at entry (P < 0.05). Improvements were also noted in receptive vocabulary, reading, perceptual discrimination and reasoning, divided attention, motor strength, and in mood and affect. Improvements in those latter functions were generally of limited magnitude and were of comparable size for both compromised and non-compromised patients. There was no overall difference between the two drug regimens in the effects on CNS parameters. CONCLUSIONS: Therapy-related improvements were noted particularly for patients with HIV-1-associated CNS compromise. Neuropsychological functions that have been implicated in AIDS dementia--memory and attention--showed the greatest gains. In contrast to the previously described superiority of the simultaneous regimen with regard to immunologic and virologic parameters, there was no difference between the regimens with regard to CNS measures. This supports the contention that the CNS constitutes a relative independent compartment in terms of HIV disease and treatment.

AIDS Dementia Complex↗
PubMed1997

Removal of human immunodeficiency virus type 1 (HIV-1) protease inhibitors from preparations of immature HIV-1 virions does not result in an increase in infectivity or the appearance of mature morphology.

The processing of gag and gag-pol polyproteins by human immunodeficiency virus type 1 (HIV-1) protease is a crucial step in the formation of infectious HIV-1 virions. In this study, we examine whether particles produced in the presence of inhibitors of HIV-1 protease can subsequently undergo gag polyprotein cleavage with restoration of infectivity following removal of the inhibitors. Viral particles produced during 7 days of culture in the presence of the protease inhibitors KNI-272 (10 microM) and saquinavir (5 microM) contained predominantly p55gag polyprotein but little or no p24gag cleavage product. Following resuspension of the particles in medium free of the inhibitor, some gag polyprotein processing was detected in particles produced from the KNI-272-treated cells, but not from the saquinavir-treated cells within the first 3 h. However, the majority of the protein remained as p55gag throughout a 48-h experimental period. The infectivity (50% tissue culture infective dose per milliliter) of the viral particles from KNI-272-treated cells was 10(6)-fold lower than that of control particles and did not significantly increase over the 48 h after the inhibitor was removed, despite the apparent return of protease function in a subset of these virions. This failure to restore infectivity was due neither to a reduction in the number of particles produced by protease inhibitor-treated cells nor to a failure of HIV RNA to be packaged in the virions. These particles also failed to express the mature phenotype by electron microscopy. Thus, while some processing of the gag polyprotein can occur in isolated HIV virions, this does not appear to be sufficient to restore infectivity in the majority of particles. This finding suggests that there may be constraints on postbudding polyprotein processing in the production of viable particles. These results should have positive implications regarding the use of protease inhibitors as anti-HIV drugs.

Blotting, Western↗
PubMed1997

In vitro induction of human immunodeficiency virus type 1 variants resistant to 2'-beta-Fluoro-2',3'-dideoxyadenosine.

2'-beta-Fluoro-2',3'-dideoxyadenosine (F-ddA) is an acid-stable purine dideoxynucleoside analog active against a wide spectrum of human immunodeficiency virus type 1 (HIV-1) and HIV-2 strains in vitro. F-ddA is presently undergoing a phase I clinical trial at the National Cancer Institute. We induced HIV-1 variants resistant to F-ddA by exposing wild-type HIV-1 (HIV-1LAI) to increasing concentrations of F-ddA in vitro. After 18 passages, the virus was fourfold less sensitive to F-ddA than HIV-1LAI. Sequence analyses of the passage 18 virus revealed changes in three amino acids in the reverse transcriptase (RT)-encoding region of the pol gene: P to S at codon 119 (P119S; present in 3 of 13 and 28 of 28 molecular clones before and after F-ddA exposure, respectively), V179D (0 of 13 and 9 of 28, respectively), and L214F (9 of 13 and 28 of 28, respectively). Drug sensitivity assays using recombinant infectious clones confirmed that P119S was directly responsible for the reduced sensitivity of HIV-1 to F-ddA. Various infectious clones with single or multiple amino acid substitutions conferring viral resistance against nucleoside RT inhibitors, including HIV-1 variants with multi-dideoxynucleoside resistance, were generally sensitive to F-ddA. The moderate level of resistance of HIV-1 to F-ddA, together with the lack of conferment of significant cross-resistance by the F-ddA-associated amino acid substitutions, warrants further investigation of F-ddA as a potential antiviral agent for use in treatment of HIV-1 infection.

Animals↗
PubMed1996

Phosphodiester amidates of allenic nucleoside analogues: anti-HIV activity and possible mechanism of action.

Lipophilic phosphodiester amidates 2a, 2b, 4a, 4b, and 6 derived from anti-HIV agent adenallene 1a, 3a, inactive hypoxallene 1b, 3b, and 9-(4-hydroxy-2-butyn-1-yl)adenine (5) were synthesized and studied as inhibitors of HIV-1 in ATH8 cell system. All phosphodiester amidates were more biologically active than their parent nonphosphorylated compounds. Analogues 2a and 4a derived from (+/-)-adenallene 1a and (R)-enantiomer 3a are effective anti-HIV agents with EC50 approximately 0.88 and 0.21 microM, respectively. Both analogues are 16 and 28 times more effective than parent compounds 1a and 3a, respectively. Some anti-HIV activity of hypoxallene derivatives 2b and 4b was noted in the range of 0.1-10 microM but the dose-response relationship was poor. Phosphodiester amidate analogue 6 also exhibited anti-HIV activity in the range of 0.1-100 microM, but this effect was accompanied by cytotoxicity. Hydrolytic studies performed at pH 9.8 and with pig liver esterase at pH 7.4 have shown that analogue 2a gives adenallene 4'-phosphoralaninate (10a) as the major product. These results can be interpreted in terms of initial hydrolysis of phosphodiester amidates 2a, 2b, 4a, 4b, and 6 catalyzed by intracellular esterase(s) to give stable phosphomonoester amidate intermediates with a free carboxyl group. The results obtained with hypoxallene phosphoramidates 2b and 4b indicate that the aminosuccinate-fumarate enzyme system responsible for activation of AIDS drug ddIno (didanosine, Videx) can also, albeit less efficiently, activate hypoxallene 4'-phosphate (9b) and the respective (R)-enantiomer released inside the HIV-infected cells.

Adenosine Monophosphate↗