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Biomedical subjects

K Ikuta

Publications and source records attributed to K Ikuta.

At least 73 records · Page 4Linked to original sources
PubMed2000

Highly variable sequences in the env V3 region of HIV type 1 distributing among Thai carriers from 1995 to 1997.

The amino acid sequences of the Env V3 region of HIV-1 subtype E in Thailand were highly variable in the samples obtained from 1995 to 1997, compared with the previously reported sequences in samples obtained from 1990 to 1993. The sequences of the V3 region in the samples from five provinces in Thailand revealed that the variability was much higher in the samples from Bangkok and Ubonrachathani than in those from Chiangmai, Prathumthani, and Trang. There was no apparently different level of diversity at the V3 region in the samples from symptomatic and asymptomatic individuals. The V3 loop motif in most (66.7%) of the samples was GPGQ, although this motif was more heterogeneous in the samples from Bangkok and Ubonrachathani than in those from the other three provinces. The N-linked glycosylation sites in the V3 region among these samples were relatively conserved. There was no apparent difference in the presence of positively charged amino acids at positions 306 and 320 between the samples from symptomatic and asymptomatic individuals.

Amino Acid Sequence↗
PubMed2000

Replication ability in vitro and in vivo of equine infectious anemia virus avirulent Japanese strain.

An attenuated equine infectious anemia virus (EIAV), V26, was previously prepared by 50 passages of the Japanese virulent strain V70 in primary horse macrophage culture. The horses inoculated with this V26 virus were shown to raise neutralizing antibodies against V70 without any viremia. Here, we investigated the in vitro and in vivo replication ability of V26. Comparison of the long-terminal repeat (LTR) sequences between V26 and V70 revealed a large insertion within the LTR U3 hypervariable region of V26. V26 with the mutation in the LTR showed much higher promoter activity in vitro than V70. This is consistent with the much higher replication rate of V26 in horse primary macrophage cultures compared with V70. In sharp contrast, we failed to identify the V26-specific LTR sequence by PCR, at least in sequential samples of plasma or peripheral blood mononuclear cells derived from three horses until day 62 after V26 inoculation. In contrast, antibody responses to EIAV were observed in all horses. The results suggest that the replication ability of V26 in vivo is extremely low. When one of the horses was subsequently challenged with cell-associated V70, it was found that the horse became PCR positive for EIAV. There was no LTR mutation in EIAV genome in samples periodically prepared from the V70-challenged horse. Thus it was suggested that the LTR mutation in EIAV, which occurs during serial passage in vitro, affects EIAV replication in vitro and in vivo.

Animals↗
PubMed2000

Roles of melatonin in gonadal maturation of underyearling precocious male masu salmon.

Testicular maturation of underyearling precocious male masu salmon (Oncorhynchus masou) is affected by photoperiod. It is accelerated by a short photoperiod (light-dark cycles of 8:16 h; LD 8:16) and delayed by a long photoperiod (LD 16:8). Circulating melatonin levels are high during the night and low during the day:the duration of the nocturnal elevation is longer under a short than under a long photoperiod, suggesting mediation of photoperiodic signals by melatonin. This study examined whether melatonin administration mimics short photoperiodic effects and whether it accelerates the testicular development of underyearling male masu salmon reared under a long photoperiod. Fish were randomly selected in June and were divided into two groups. They were reared under LD 16:8 (lights on 04:00-20:00 h) and fed pellets sprayed with melatonin (0.5 mg melatonin/kg body weight/day) or vehicle once a day at 11:00 h until October. The plasma melatonin profile of the melatonin-treated group was similar to that expected under a short photoperiod. Melatonin treatment had a stimulatory effect on the gonadosomatic index and pituitary gonadotropin (GTH) I contents. Plasma testosterone levels were significantly higher in the melatonin-treated group than in the control group in August. However, spermiation was observed in October in both groups and no significant differences were observed in GTH II contents in the pituitary in the two groups throughout the experiment. These results suggest that mimicking a short photoperiod by melatonin administration stimulated testicular development but did not completely activate the brain-pituitary-gonadal axis in precocious male masu salmon. Thus, melatonin is suggested to be one of the factors that mediates the transduction of photoperiodic information to the brain-pituitary-gonadal axis.

Administration, Oral↗
PubMed2000

Acidification severely suppresses spawning of hime salmon (land-locked sockeye salmon, Oncorhynchus nerka).

A laboratory study was conducted to investigate the effects of an acidic environment on the female sexual behavior of hime salmon (land-locked sockeye salmon, Oncorhynchus nerka). Spawning hime salmon were extremely sensitive to the acidity of ambient water. Nest-digging behavior was severely inhibited (P<0.05) by very slight acidification (pH below 6.4) of the water. Below pH 6.0, females showed almost no diggings. When the ambient water was returned to nearly neutral (pH 6.6), diggings reappeared in four of the six fish tested, whereas in two individuals, none was observed. Avoidance of slightly acidic water in selection of spawning site or cessation of spawning behavior in weakly acidic environments may be the most potent cause of the reduction of salmonid populations in the early stages of acidification.

Animals↗
PubMed2000

Mutations occurring during serial passage of Japanese equine infectious anemia virus in primary horse macrophages.

An attenuated equine infectious anemia virus (EIAV), named V26, was previously obtained after 50 passages of the Japanese virulent strain V70 in primary macrophage culture. To clarify the differences between both viruses, their full-length sequences were determined. There were higher mutations in S2 (6.15% amino acid difference) and LTR (10.7% nucleotide difference). The presumed initiation codon of the S2 gene was absent from the sequence of V26. There was a large insertion within the long-terminal repeat (LTR) U3 hypervariable region of V26. In addition, there were minor mutations in gag (1.22% amino acid difference), pol (1.05% amino acid difference) and env (1. 65% amino acid difference) regions, but no mutation in tat region. No mutations were observed in the principal neutralizing domain in the gp90. Thus, the mutations in the S2 and LTR might be the major target sites of mutation in EIAV during serial passages in vitro.

Amino Acid Sequence↗
PubMed2000

Fusion of uninfected T-cells occurs with immature HIV-1 protease-mutant, but not morphologically similar protease inhibitor derived particles.

Protease inhibitors are widely used in the treatment of human immunodeficiency virus type 1 (HIV-1)-infected individuals and show a drastic effect on the reduction of virus load. We previously reported that doughnut-shaped, protease-defective gp120-containing HIV-1 particles from an L-2 cell clone, carrying a provirus with mutations at the pol (protease), env (gp41) and nef genes, rapidly and more effectively induces virus particle-mediated syncytia formation of uninfected T-cells, than a parental wild-type laboratory strain of HIV-1 (LAI). In this study, we examined the possibility of whether enhanced syncytia formation is mediated by morphologically similar doughnut-shaped particles obtained after treatment of LAI-infected cells with the protease inhibitors L-689, 502, DMP-323, RO-31-8959, and KNI-272. Utilizing such protease inhibitor-induced particles and a clone of MOLT-4 cells, we could not detect any enhancement of syncytia formation, over that seen with wild-type LAI particles. This result should alleviate concerns of patients on highly active antiretroviral therapy (HAART), that protease inhibitors might accelerate progression of the disease through enhanced production of defective, 'immature'-appearing particles.

Anti-HIV Agents↗
PubMed2000

Detection of Epstein-Barr virus in salivas and throat washings in healthy adults and children.

It is well known that Epstein-Barr virus (EBV) is excreted from oral regions in the patients with infectious mononucleosis. We analyzed the prevalence of EBV in saliva and throat washings from healthy people in Japan by the polymerase chain reaction assay. EBV DNA was detected in 43 (90%) of the 48 throat washings from healthy adults (21 to 57 years old) and in 35 (38%) of the 93 salivas from healthy children (0 to 6 years old). The percentages of the EBV DNA-positive ratio in salivas increased in proportion relative to the increase of the children's ages. EBV type 1 was predominant and was detected in 86 and 94% of adults and children, respectively. Umbilical cord lymphocytes were transformed by some throat washings from EBV seropositive donors. EBV DNA was detected in throat washings from two healthy adults whose EBV antibody was not detected. In both cases, higher amounts of EBV DNA were detected in their peripheral blood mononuclear cells than in those of other, EBV antibody-positive donors. These results demonstrated the incidence of EBV excretion in oral regions of healthy individuals in Japan and defined a novel type of EBV infection in healthy adults.

Adult↗
PubMed2000

Sex chromosomal analysis of spermatozoa from infertile men using fluorescence in situ hybridization.

PURPOSE: To confirm an association between male infertility and chromosome aberrations of spermatozoa, we demonstrated the frequency of numerical abnormalities of spermatozoa from infertile men with abnormal semen parameters compared with fertile controls. METHOD: Sperm cells from 10 infertile patients were investigated for disomy rates of sex chromosomes and chromosome 18 and diploidy by fluorescence in situ hybridization (FISH). All patients showed oligoasthenozoospermia with sperm counts 3-20 x 10(6)/ml and motile rates 0-40%. RESULTS: Regarding XY disomy, a significantly higher frequency was found in 8 of 10 patients as compared to normal fertile men. The disomy rates of chromosome 18, XX, YY, and diploidy rate were not increased. CONCLUSIONS: There is an association between male infertility and embryo with aneuploidy of sex chromosomes. Counseling about possible genetic risks should be provided to the infertile couples planning assisted reproduction treatment.

Aneuploidy↗
PubMed2000

Long-term follow-up of childhood acute lymphoblastic leukemia in Tokyo Children's Cancer Study Group 1981-1995.

The objectives were as follows: Firstly, to estimate the overall probability of event-free survival (EFS) and isolated CNS relapse in the studies for children with acute lymphoblastic leukemia (ALL) during the 1980s and 1990s. Secondly, to report the EFS according to presenting features and lineage. Thirdly, to evaluate the treatment results re-classified by the risks of NCI criteria. Four consecutive protocol studies were performed in the Tokyo Children's Cancer Study Group: L81-10 protocol (1981-1984, 189 patients), L84-11 (1984-1989, 484 patents), L89-12 (1989-1992, 418 patients) and L92-13 (1992-1995, 347 patients). Overall EFS at 5 years in each protocol was 56.5 +/- 3.8(1 s.e.)%, 71.0 +/- 2.1%, 67.8 +/- 2.3%, and 63.4 +/- 2.7%, respectively. The cumulative isolated CNS relapse rate at 5 years was 8.1 +/- 2.1%, 3.5 +/- 0.9%, 3.6 +/- 1.0%, 1.0 +/- 0.6. The EFS in SR/HR (standard risk/high risk) according to the NCI criteria in B-precursor ALL at 5 years was 61.9 +/- 4.3%/41.4 +/- 7.4% (lineage was not confirmed.), 72.5 +/- 2.6%/63.4 +/- 5.0%, 77.4 +/- 2.7%/56.3 +/- 4.7%, and 67.8 +/- 3.4%/56.7 +/- 5.4% in each protocol. Also EFSs according to NCI SR/HR at 5 years of T-ALL in protocols L84-11, L89-12 and L92-13 were 55.6 +/- 16.6%/60.9 +/- 10.1%, 72.7 +/- 13.4%/51.6 +/- 9.1%, and 77.1 +/- 14.4%/53.6/10.1%, respectively. The truncation of maintenance therapy to 6 months resulted in a decreased EFS in L92-13, particularly due to an increase of bone marrow relapse after cessation of therapy in SR and HR. The NCI risk criteria work properly even in the patients treated by different intensities, so that it makes the comparison possible among the patients in various groups. The overall EFSs in childhood ALL improved in 1980s, but it seemed stable or decreased in 1990s. The short maintenance therapy resulted in poor outcome in SR on the L92-13 protocol. Many of these late relapsers were effectively rescued and overall survival remained at a high level. The proportion of patients who received cranial irradiation reduced without any increase of the CNS events.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

The monoclonal antibody TER-119 recognizes a molecule associated with glycophorin A and specifically marks the late stages of murine erythroid lineage.

The antigen specificity of a rat monoclonal antibody TER-119 was investigated. In adult mice, TER-119 reacted with mature erythrocytes, 20-25% of bone marrow cells and 2-3% of spleen cells but not with thymocytes nor lymph node cells. In fetal haematopoietic tissues, 30-40% of d 10 yolk sac cells, 80-90% of d 14 fetal liver cells and 40-50% of newborn liver cells were reactive with TER-119. TER-119+ cells in adult bone marrow expressed significant levels of CD45 but not myeloid (Mac-1, Gr-1) or B-cell (B220) markers. Morphological examination and haematopoietic colony-forming assays for isolated TER-119+ cells revealed that TER-119 reacts with erythroid cells at differentiation stages from early proerythroblast to mature erythrocyte, but not with cells showing typical erythroid blast-forming unit (BFU-E) and erythroid colony-forming unit (CFU-E) activities. Erythroleukaemia cell lines do not express the TER-119 antigen even after stimulation with dimethylsulphoxide. TER-119 immunoprecipitated protein bands with molecular masses of 110 kDa, 60 kDa, 52 kDa and 32 kDa from erythrocyte membrane, whereas only a 52-kDa band was detected by TER-119 in Western blot analysis. Further molecular and cellular analyses indicated that the TER-119 antigen is a molecule associated with cell-surface glycophorin A but not with glycophorin A itself.

Animals↗
PubMed2000

Facilitatory roles of novel compounds designed from cyclopentenone prostaglandins on neurite outgrowth-promoting activities of nerve growth factor.

Cyclopentenone prostaglandins (PGs) are known to arrest the cell cycle at the G(1) phase in vitro and to suppress tumor growth in vivo. However, their effects on neurons are unclear. Here, we report that some cyclopentenone PGs function as neurite outgrowth-promoting factors. They promoted neurite outgrowth from PC12 cells and from dorsal root ganglion explants but only in the presence of nerve growth factor (NGF). We refer to these PGs as neurite outgrowth-promoting PGs (NEPPs). Through study of the structure-function relationship of NEPP1-10 and related compounds, we found that the cross-conjugated dienone moiety of NEPPs was essential for promoting neurite outgrowth, and NEPP10 was concluded to be the best candidate for drug development. We also investigated the intracellular mechanism of the promotion by NEPPs and obtained evidence that immunoglobulin heavy chain binding protein/glucose-regulated protein 78 (BiP/GRP78) plays a role in the promotion, based on the following observations: Antisense nucleotides for BiP/GRP78 gene blocked the promotion of neurite outgrowth; BiP/GRP78 protein level increased in response to NEPPs; and overexpression of BiP/GRP78 protein by adenoviral gene transfer promoted the neurite outgrowth by NGF.

Adenoviridae↗
PubMed2000

The influence of HLA genotyping compatibility on clinical outcome after cord blood transplantation from unrelated donors.

We performed retrospective DNA typing of class I (A, B, Cw) and class II (DRB1, DQB1, DPB1) HLA alleles in 27 unrelated cord blood transplantation (CBT) cases donated from a single cord blood bank (Kanagawa Cord Blood Bank). The influence of HLA genotype matching on clinical outcome was evaluated. From Cox's model, we found that incompatibility of two or more HLA alleles between the donor and recipient of an unrelated CBT was suggested to be a risk factor for a worse event-free survival (EFS) (p = 0.04; RR, 4.06; 95% CI, 1.06-15.61). Furthermore, mismatches including HLA-DRB1 alleles had an adverse effect on EFS (p = 0.04; RR, 4.91; 95% CI, 1.01-24.02). For definite conclusions on the role of HLA allele typing in unrelated CBT, more accumulation of data and analysis will be required.

Actuarial Analysis↗
PubMed2000

Exposure of normal monocyte-derived dendritic cells to human immunodeficiency virus type-1 particles leads to the induction of apoptosis in co-cultured CD4+ as well as CD8+ T cells.

The depletion of immune T cells by human immunodeficiency virus type-1 (HIV-1) infection is a major mechanism involved in the pathogenesis of AIDS. Here, we examined a possible effector function of blood monocyte-derived dendritic cells (DCs) to induce apoptosis in bystander CD4+ and CD8+ T cells. The DCs were generated by culturing monocytes in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4. The DCs exposed to HIV-1 particles were co-cultured with healthy donor-derived blood T cells at a ratio of 1:20. Analyses by percent cell mortality, staining with propidium iodide and reactivity with Annexin V revealed the induction of apoptosis in both CD4+ and CD8+ target T cells. Further, this apoptosis occurred without stimulation with mitogens when the cell cycle of target T cells shifted from G0 to G1, probably due to the mitogenic effect of the DCs. Thus, induction of apoptosis in both CD4+ and CD8+ T cells occurred via interaction with DCs adsorbed with HIV-1 particles.

Apoptosis↗
PubMed2000

Molecular ratio between borna disease viral-p40 and -p24 proteins in infected cells determined by quantitative antigen capture ELISA.

We developed the antigen capture enzyme-linked immunosorbent assay (ELISA) systems for quantification of Borna disease virus (BDV) major antigens, p40 and p24. Using these ELISAs, we quantified the two proteins in various BDV-infected materials, including the cell lysates and culture supernatants as well as the homogenates of experimental animal brains. The ELISAs were also applied to measure the infectious titer of BDV in persistently infected cell lines. Quantitative analysis with these ELISAs allowed us to measure the molecular ratio between the p40 and p24 in infected samples. Interestingly, the ratio of p24 to p40 in persistently infected cells was much higher than that observed in acutely infected cells although the ratios in the supernatants from both cell lines were quite similar. BDV-inoculated gerbil brain cells showed a relatively high ratio of p24 to p40 as compared with acutely infected cells. These observations suggested that the molecular ratio between the proteins strongly depended on the infectious status of BDV in the host cells. The ELISA system developed here could be a convenient method for the quantification of BDV infection and may also be beneficial for understanding viral replication and infectious status in the host cells.

Animals↗
PubMed2000

Isolation of Borna disease virus from human brain tissue.

Serological and molecular epidemiological studies indicate that Borna disease virus (BDV) can infect humans and is possibly associated with certain neuropsychiatric disorders. We examined brain tissue collected at autopsy from four schizophrenic patients and two healthy controls for the presence of BDV markers in 12 different brain regions. BDV RNA and antigen was detected in four brain regions of a BDV-seropositive schizophrenic patient (P2) with a very recent (2 years) onset of disease. BDV markers exhibited a regionally localized distribution. BDV RNA was found in newborn Mongolian gerbils intracranially inoculated with homogenates from BDV-positive brain regions of P2. Human oligodendroglia (OL) cells inoculated with brain homogenates from BDV-positive gerbils allowed propagation and isolation of BDVHuP2br, a human brain-derived BDV. Virus isolation was also possible by transfection of Vero cells with ribonucleoprotein complexes prepared from BDV-positive human and gerbil brain tissues. BDVHuP2br was genetically closely related to but distinct from previously reported human- and animal-derived BDV sequences.

Adolescent↗
PubMed2000

Positive and negative aspects of the human immunodeficiency virus protease: development of inhibitors versus its role in AIDS pathogenesis.

In this review we summarize multiple aspects of the human immunodeficiency virus (HIV) protease from both structural and functional viewpoints. After an introductory overview, we provide an up-to-date status report on protease inhibitors (PI). This proceeds from a discussion of PI structural design, to how PI are optimally utilized in highly active antiretroviral triple therapy (one PI along with two reverse transcriptase inhibitors), the emergence of PI resistance, and the natural role of secretory leukocyte PI. Then we switch to another focus: the interaction of HIV protease with other genes in acute and persistent infection, which in turn may have an effect on AIDS pathogenesis. We conclude with a discussion on future directions in HIV treatment, involving multiple-target anti-HIV therapy, vaccine development, and novel reactivation-inhibitory reagents.

AIDS Vaccines↗
PubMed2000

Six months of maintenance chemotherapy after intensified treatment for acute lymphoblastic leukemia of childhood.

PURPOSE: We postulated that intensification of chemotherapy immediately after remission induction might reduce the leukemic cell burden sufficiently to allow an abbreviated period of antimetabolite therapy. PATIENTS AND METHODS: Three hundred forty-seven children (ages 1 to 15 years) with previously untreated acute lymphoblastic leukemia (ALL) were enrolled onto the Tokyo L92-13 study, which excluded patients with mature B-cell ALL and patients less than 1 year old. One hundred twenty-four patients were classified as standard risk, 122 as high risk, and 101 as extremely high risk, according to age, peripheral-blood leukocyte count, selected genetic abnormalities, and immunophenotype. All subjects received four drugs for remission induction, followed by a risk-directed multidrug intensification phase and therapy for presymptomatic leukemia in the CNS. Maintenance chemotherapy with oral mercaptopurine and methotrexate was administered for 6 months, with all treatment stopped by 1 year after diagnosis. RESULTS: The mean (+/- SD) event-free survival (EFS) and overall survival rates for all patients were 59.5% +/- 3.4% and 81.5% +/- 2.2%, respectively, at 5. 5 years after diagnosis. EFS rates by risk category were similar (60. 2% +/- 6.0% for standard risk, 57.7% +/- 5.6% for high risk, and 62. 5% +/- 5.7% for extremely high risk), whereas overall survival rates differed significantly (91.2% +/- 2.7%, 80.0% +/- 4.1%, and 72.1% +/- 4.5%, respectively, P <.0001 by the log-rank test). There were 107 relapses. Eighty-five (79.4%) of these 107 patients achieved second complete remissions, with subsequent EFS rates of 61.5% +/- 7. 9% (standard risk), 42.6% +/- 8.1% (high risk), and 9.6% +/- 6.4% (extremely high risk). Of the five risk factors analyzed, only the response to prednisolone monotherapy among extremely high-risk patients proved important. CONCLUSION: Early treatment intensification did not compensate for a truncated phase of maintenance chemotherapy in children with standard- or high-risk ALL. However, 6 months of antimetabolite treatment seemed adequate for extremely high-risk patients who were good responders to prednisolone and received intensified chemotherapy that included high-dose cytarabine early in the clinical course.

Adolescent↗