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Biomedical subjects

Y Takebe

Publications and source records attributed to Y Takebe.

At least 37 records · Page 2Linked to original sources
PubMed1999

Genetic similarity of HIV type 1 subtype E in a recent outbreak among injecting drug users in northern Vietnam to strains in Guangxi Province of southern China.

To investigate the molecular epidemiology of a recent HIV-1 outbreak in northern Vietnam and its relation to the epidemic in surrounding areas, we analyzed 17 HIV-positive blood specimens from 3 heterosexuals, 2 sexually transmitted disease patients, and 12 injecting drug users (IDUs), collected in 4 provinces near Hanoi in 1998. These were compared with the specimens from Ho Chi Minh City (n = 10) and An Giang Province (n = 10) in southern Vietnam and with published sequences from neighboring countries. Genetic subtyping based on the env C2/V3 sequences revealed that HIV-1 subtype E predominated throughout Vietnam in all risk populations; the exception was one typical United States-European-type HIV-1 subtype B detected in a patient in Ho Chi Minh City, the first case of HIV infection identified in Vietnam in 1990. The HIV-1 subtype E sequences identified in 9 of the 12 IDUs from northern provinces were closely related phylogenetically to those in IDUs in nearby Guangxi Province of China, and also shared a common amino acid signature downstream of the env V3 loop region. The low interperson nucleotide diversity among IDUs in northern Vietnam supports the view that HIV-1 subtype E was introduced recently among IDUs in northern Vietnam. These data indicate a linkage between HIV-1 circulating among IDUs in northern Vietnam and southern China, and suggest recent transborder introductions as the likely source of HIV-1 subtype E in northern Vietnam.

Adolescent↗
PubMed1999

Sendai virus-based production of HIV type 1 subtype B and subtype E envelope glycoprotein 120 antigens and their use for highly sensitive detection of subtype-specific serum antibodies.

We previously described a Sendai virus (SeV)-based expression system for the recombinant gp120 of HIV-1 subtype B (rgp120-B), which has permitted the production of antigenetically and functionally authentic gp120 at a concentration as high as 6 microg/ml of culture supernatant (Yu D et al.: Genes Cells 1997;2:457-466). Here the same procedure was successfully applied to the production of HIV-1 subtype E gp120 (rgp120-E). The remarkable production of the proteins by the SeV expression system enabled us to use crude culture supernatants for serological and functional studies of gp120s. The immunological authenticity of rgp120-E was verified by patient sera and anti-V3 loop monoclonal antibodies specific for HIV-1 subtypes B and E. CD4-binding properties were corroborated by FACS analyses. The rgp120s were then used in an enzyme immunoassay (rgp120-EIA) to detect antibodies in the sera of HIV-1-infected individuals, and the performance was assessed in comparison with a conventional V3 loop peptide EIA (V3-EIA). The initial evaluation of a serum panel (n = 164) consisting of 76 subtype E and 88 subtype B sera revealed that the rgp120-EIA was nearly 1000-fold more sensitive than the V3-EIA and was able to detect subtype-specific antibody with 100% sensitivity and with a complete correlation with the genotypes, whereas the V3-EIA failed to detect 9 and 24% of the same subtype E and B sera, respectively. Furthermore, a study employing a panel of 28 international sera with known genotypes (HIV-1 subtypes A through F) confirmed the remarkable specificity of this method. An EIA reactivity higher than 1.0 was an unambiguous predictor of HIV-1 subtype E and B infections. The data imply the presence of strong subtype-specific epitopes for antibody bindings to these rgp120s.

Antibodies, Viral↗
PubMed1999

Functional complementation of the envelope hypervariable V3 loop of human immunodeficiency virus type 1 subtype B by the subtype E V3 loop.

The hypervariable V3 loop within gp120 of human immunodeficiency virus type 1 (HIV-1) is the major determinant of cell tropism and the entry coreceptor usage of the virus. However, the information obtained thus far has been from only subtype B from North America and Europe, and little is known about other subtypes whose V3 amino acids differ by as much as 50% from subtype B V3. In this study, we examined the functional potential of the V3 element of the HIV-1 subtype E, the most crucial variant causing the AIDS epidemic throughout southeast Asia. A panel of HIV-1LAI recombinants was constructed by the overlap extension method, by which the LAI V3 loop was precisely replaced by that of the subtype E nonsyncytium-inducing (NSI) or syncytium-inducing (SI) variant. All of the recombinant viruses infected peripheral blood mononuclear cells, whereas only those with SI V3 infected MT2 cells, a CD4(+) T cell line. Consistently, the SI V3 recombinants used CXCR4, while the NSI V3 recombinants used CCR5 for infection of HOS-CD4(+) cells. Finally, only the NSI V3 sequence conferred CC-chemokine sensitivity on the parental virus. The data support the notion that the HIV-1 V3 loop consists of a relatively independent domain in gp120 and suggest that the subtype E V3 loop indeed contains the functional element to dictate the cell tropism, coreceptor preference, and chemokine sensitivity of the virus. These findings are of immediate importance in understanding V3 structure-function relationship and for examining phenotypic evolution of HIV-1 subtype E.

Amino Acid Sequence↗
PubMed1999

Polymorphism in RANTES chemokine promoter affects HIV-1 disease progression.

RANTES (regulated on activation normal T cell expressed and secreted) is one of the natural ligands for the chemokine receptor CCR5 and potently suppresses in vitro replication of the R5 strains of HIV-1, which use CCR5 as a coreceptor. Previous studies showed that peripheral blood mononuclear cells or CD4(+) lymphocytes obtained from different individuals had wide variations in their ability to secrete RANTES. These findings prompted us to analyze the upstream noncoding region of the RANTES gene, which contains cis-acting elements involved in RANTES promoter activity, in 272 HIV-1-infected and 193 non-HIV-1-infected individuals in Japan. Our results showed that there were two polymorphic positions, one of which was associated with reduced CD4(+) lymphocyte depletion rates during untreated periods in HIV-1-infected individuals. This mutation, RANTES-28G, occurred at an allele frequency of approximately 17% in the non-HIV-1-infected Japanese population and exerted no influence on the incidence of HIV-1 infection. Functional analyses of RANTES promoter activity indicated that the RANTES-28G mutation increases transcription of the RANTES gene. Taken together, these data suggest that the RANTES-28G mutation increases RANTES expression in HIV-1-infected individuals and thus delays the progression of the HIV-1 disease.

Base Sequence↗
PubMed1999

Evolution and biological characterization of human immunodeficiency virus type 1 subtype E gp120 V3 sequences following horizontal and vertical virus transmission in a single family.

It has been suggested that immune-pressure-mediated positive selection operates to maintain the antigenic polymorphism on the third variable (V3) loop of the gp120 of human immunodeficiency virus type 1 (HIV-1). Here we present evidence, on the basis of sequencing 147 independently cloned env C2/V3 segments from a single family (father, mother, and their child), that the intensity of positive selection is related to the V3 lineage. Phylogenetic analysis and amino acid comparison of env C2/V3 and gag p17/24 regions indicated that a single HIV-1 subtype E source had infected the family. The analyses of unique env C2/V3 clones revealed that two V3 lineage groups had evolved in the parents. Group 1 was maintained with low variation in all three family members regardless of the clinical state or the length of infection, whereas group 2 was only present in symptomatic individuals and was more positively charged and diverse than group 1. Only virus isolates carrying the group 2 V3 sequences infected and induced syncytia in MT2 cells, a transformed CD4(+)-T-cell line. A statistically significant excess of nonsynonymous substitutions versus synonymous substitutions was demonstrated only for the group 2 V3 region. The data suggest that HIV-1 variants, possessing the more homogeneous group 1 V3 element and exhibiting the non-syncytium-inducing phenotype, persist in infected individuals independent of clinical status and appear to be more resistant to positive selection pressure.

Amino Acid Sequence↗
PubMed1999

Role of naturally occurring basic amino acid substitutions in the human immunodeficiency virus type 1 subtype E envelope V3 loop on viral coreceptor usage and cell tropism.

To assess the role of naturally occurring basic amino acid substitutions in the V3 loop of human immunodeficiency virus type 1 (HIV-1) subtype E on viral coreceptor usage and cell tropism, we have constructed a panel of chimeric viruses with mutant V3 loops of HIV-1 subtype E in the genetic background of HIV-1LAI. The arginine substitutions naturally occurring at positions 8, 11, and 18 of the V3 loop in an HIV-1 subtype E X4 strain were systematically introduced into that of an R5 strain to generate a series of V3 loop mutant chimera. These chimeric viruses were employed in virus infectivity assays using HOS-CD4 cells expressing either CCR5 or CXCR4, peripheral blood mononuclear cells, T-cell lines, or macrophages. The arginine substitution at position 11 of the V3 loop uniformly caused the loss of infectivity in HOS-CD4-CCR5 cells, indicating that position 11 is critical for utilization of CCR5. CXCR4 usage was conferred by a minimum of two arginine substitutions, regardless of combination, whereas arginine substitutions at position 8 and 11 were required for T-cell line tropism. Nonetheless, macrophage tropism was not conferred by the V3 loop of subtype E R5 strain per se. We found that the specific combinations of amino acid changes in HIV-1 subtype E env V3 loop are critical for determining viral coreceptor usage and cell tropism. However, the ability to infect HOS-CD4 cells through either CXCR4 or CCR5 is not necessarily correlated with T-cell or macrophage tropism, suggesting that cellular tropism is not dictated solely by viral coreceptor utilization.

Amino Acid Sequence↗
PubMed1998

Genetic and serologic characterization of HIV type 1 prevailing in Myanmar (Burma).

To study the molecular epidemiology of HIV-1 spread in Myanmar and the interplay with the epidemic in surrounding Southeast Asian countries, we determined the HIV-1 subtypes prevailing in Myanmar. Thirty HIV-positive blood specimens were sampled in the capital city, Yangon, and an additional 459 sera were collected nationwide in 1995. Genetic subtyping based on the env C2/V3 sequence and serologic data, using a V3 peptide enzyme immunoassay (PEIA), revealed three patterns of HIV spread in different geographic regions in Myanmar: (1) in the capital city, Yangon, HIV-1 subtype B' ("Thai-B" cluster within subtype B) predominated both in IDUs and heterosexuals; (2) in the cities near the border with Thailand, including Tachelaik and Kawthaung, where heterosexual transmission is a major pathway of HIV-1 spread, HIV-1 subtype E was predominantly distributed among the commercial sex workers and heterosexuals; (3) in central and northeast Myanmar, both HIV-1 subtypes B' and E occurred in a mixed distribution, without showing any significant segregation by risk group. In addition, the PEIA data implied the occurrence of other subtype(s) in these areas. The interperson nucleotide sequence variations in env C2/V3 regions of B' and E, prevailing in Yangon, were 6.7 +/- 2.1 and 7.1 +/- 0.7%, respectively. They were similar to those levels observed in Thailand. These findings are consistent with the view that HIV spread in Myanmar might have taken place at about the same time as that in Thailand, and that multiple entries and exchanges of HIV-1 with neighboring countries are important factors contributing to the current distribution of subtypes in Myanmar.

Amino Acid Sequence↗
PubMed1998

A simple assay system for examination of the inhibitory potential in vivo of decoy RNAs, ribozymes and other drugs by measuring the Tat-mediated transcription of a fusion gene composed of the long terminal repeat of HIV-1 and a gene for luciferase.

Nucleic acid-based drugs, including antisense RNA and DNA, ribozymes and decoys appear to have potential for the suppression of the expression of specific genes. To allow the examination of the potential of such agents in vivo as anti-HIV drugs in standard laboratories, where facilities for handling live virions are not available, we constructed a simple assay system (HIV-1 model) that allows measurement of the extent of inhibition of Tat-mediated transcription of HIV-1 by nucleic acid-based drugs and other agents. In cells that harbor a stable chimeric long terminal repeat (LTR)-Luc construct (a fusion gene consisting of the LTR of HIV-1 and the gene for luciferase), total luciferase activity in an aliquot of cell lysate is dose- and promoter-dependent on transfection with a Tat expression plasmid, reflecting the character of the LTR promoter of HIV. When HeLa cells were co-transfected with the Tat expression plasmid and another plasmid that encoded the U6 promoter or the promoter of the gene for tRNA(Val) linked to the trans-activating response (TAR) sequence, total luciferase activity was inhibited by 60 or 40%, respectively. The inhibition was also dependent on the dose of the TAR expression plasmid. These results demonstrate the usefulness of this simple assay system for detection of the efficacy of a decoy RNA or a ribozyme in vivo, without a requirement for HIV-infected cells, by measurement of luciferase activity in vitro.

Artificial Gene Fusion↗
PubMed1998

Identification and molecular characterization of human T lymphotropic virus type II infections in intravenous drug abusers in the former South Vietnam.

Previous serological studies have demonstrated that some 60% of intravenous drug abusers (IVDAs) in urban areas of the former South Vietnam are infected with HTLV-II. In the present report we have attempted to characterize the viruses using restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis of the provirus long terminal repeat (LTR) region. RFLP analysis of nine samples demonstrated that all were infected with the HTLV-IIb subtype. The HTLV-IIa subtype was not detected. Phylogenetic analysis of the nucleotide sequences demonstrated that the viruses clustered closely with HTLV-IIb isolates present in IVDAs from the New York City area. The present molecular analysis together with the previously reported absence of HTLV-II infection in North Vietnam supports the view that HTLV-II may have been introduced from the United States to this part of Asia by military personnel during the Vietnam conflict.

HTLV-II Infections↗
PubMed1998

Large quantity production with extreme convenience of human SDF-1alpha and SDF-1beta by a Sendai virus vector.

We describe a robust expression of human stromal cell-derived factor-1alpha (SDF-1alpha) and SDF-1beta, the members of CXC-chemokine family, with a novel vector system based upon Sendai virus, a non-segmented negative strand RNA virus. Recombinant SDF-1alpha and SDF-1beta were detected as a major protein species in culture supernatants, reached as high as 10 microg/ ml. This remarkable enrichment of the products allowed us to use even the crude supernatants as the source for biological and antiviral assays without further concentration nor purification and will thus greatly facilitate to screen their genetically engineered derivatives.

Anti-HIV Agents↗
PubMed1998

[Treatment of tuberculous meningitis: marker of cure].

A 49-year-old male with tuberculous meningitis was reported. When admitted to our hospital with mild right hemiparesis, he was alert but he developed disorientation 7 days later. A diagnosis of tuberculous meningitis was reached because of elevated levels of adenosine-deaminase at 19.6U/liter in the cerebrospinal fluid. MRI showed a marked enhancement in the basal cisterns and an enhanced intraparenchymal lesion in the brainstem. Chronological changes of MRI findings did not closely correlate with the clinical course. Slight meningeal enhancement on MRI seems to remain for a long time without active tuberculous meningitis, and absence of the meningeal enhancement on MRI is not necessarily appropriate as a marker of cure of tuberculous meningitis.

Adenosine Deaminase↗
PubMed1998

[Predictability of EC/IC bypass function: a retrospective study].

Although the efficacy of extracranial/intracranial bypass for reduction of risk of ischemic stroke has been denied, we have encountered patients in whom bypass operation seems to have improved his or her clinical course. The efficacy of bypass should be evaluated not by the patency of the bypass but by the extent of collateral circulation brought about by the bypass. We retrospectively analyzed our patients to determine whether the extent of bypass flow could be predicted from the results of preoperative studies. In 18 hemispheres of 18 consecutive patients who underwent extracranial/intracranial bypass surgery, correlation between the extent of bypass flow and the multiple preoperative factors including the angiographic findings were investigated. The bypass function was highly predictable in the light of preoperative studies. In all of 10 hemispheres in patients under 70 years of age and with occlusive lesions in the proximal portion of the middle cerebral artery, collateral circulation through the bypass developed to an extensive or a moderate degree. In 9 of 10 hemispheres in which an interval between the latest attack and the diagnosis of hemodynamic failure was 4 weeks or longer, collateral circulation through the bypass was shown to have developed to an extensive or a moderate degree. Our results indicate that extensive or moderate collateral circulation through the bypass can be expected only in patients under 70 years of age, with lesions in the proximal portion of the middle cerebral artery, and in whom an interval between the latest attack and diagnosis of hemodynamic failure was 4 weeks or more.

Adult↗
PubMed1997

Inclusion of Volatile Organic Compounds into Natural Cyclodextrins and Their Branched Cyclodextrins in the Gaseous Phase

The adsorption isotherms of water, the differential heat of adsorption, and the entropy of adsorbed water were investigated to elucidate the structure of stability of cyclodextrins (CyD) and branched CyD's. The amount adsorbed on branched CyD's increased with increasing relative humidity. The steep rise in the amount adsorbed at higher relative humidities indicated that the structure of branched CyD's was affected by the water molecules at these higher relative humidities. The bonding force between alpha-CyD's and water molecules was stronger than that between their branched CyD's and water, while that between beta-CyD's and water was weaker than that between their branched CyD's and water. We have used activated carbons for the recovery of organic solvents. There are polar groups on the activated carbon surface. Therefore, the recovered organic solvents were degraded by these groups. However, such polar groups are not expected for the hydroxyl groups of the CyD's. The amounts of 1,1,1-trichloroethane, benzene, and toluene included in natural CyD's and their branched CyD's were measured. The amounts of organic solvents included in the CyD's depended upon the cavity radii and the glucosyl and maltosyl functional groups of the CyD's and the radii of the organic solvent molecules.

Journal Article↗
PubMed1997

A polypeptide encoded within the murine AIDS defective virus stimulates primary proliferation of CD8+ T-cells.

The murine AIDS (MAIDS) is a retrovirus-induced disease that shows severe immunodeficiency with abnormal lymphoproliferation in susceptible strains of mice. To clarify the antigenicity of gag gene products of the LP-BM5 defective virus, which is known as the causative virus of MAIDS, we expressed and purified the gag p12 gene product (P12) by using a baculovirus expression vector system. The P12 protein strongly stimulated the proliferation of normal C57BL/6 (B6) lymph node T-cells in vitro. Furthermore, a 25-mer synthetic polypeptide within the P12 sequence gave rise to the similar or even higher activation of T-cells. The phenotype of responding T-cells was found to be CD8+ CD44low, indicating that naive CD8+ T-cells respond against a peptide encoded within a MAIDS defective virus gag p12 gene. Finally, the expression of T-cell receptor (TcR) V beta on the responding CD8+ T-cells was analyzed. Although CD8+ T-cells with the particular V beta chains were expanded in response to the 25-mer peptide, this polypeptide does not seem to be a superantigen, since this response is MHC class I-restricted and the V beta preference is not striking. The presentation pathway of this highly antigenic polypeptide will be discussed.

Amino Acid Sequence↗
PubMed1997

Nucleotide sequence variation of human T-lymphotropic virus type II in Vietnam.

A high rate of human T-lymphotropic virus type II (HTLV-II) infection has been documented in intravenous drug abusers (IVDAs) in South Vietnam. We have investigated the molecular characteristics of the virus and have shown that one HTLV-II subtype is predominant in Ho Chi Minh City. This molecular subtype, HTLV-IIb, was identified in a number of South Vietnamese by nucleotide sequence analysis of the long terminal repeat (LTR) region. HTLV-IIa was not found. These findings suggest that HTLV-IIb is endemic in IVDAs in South Vietnam, although IVDAs in urban areas in North America are predominantly infected with HTLV-IIa.

Adult↗
PubMed1997

[Simple method for typing human immunodeficiency virus type I (B, E) by PCR and chronological change of distribution of subtype (B to E) in Japan].

We analyzed the clade distribution of B and E in HIV-1 isolates in Japan by a nested PCR method using 5'-CCCACAAGATTTAAATATG-3' of the gag gene as clade B primer and 5'-CCCACAAGATTTAAACTCC-3' of the gag gene as clade E primer. Seventy-two anti-HIV-1 confirmatory positive serum samples were collected during a period of 1991-1996 in two hospitals in Yokohama City. Peripheral blood mononuclear cells were obtained from the buffy coat of these samples and extracted DNA were used for nested PCR. The 72 cases comprised of 11 Japanese hemophiliacs, 14 Japanese male homosexuals, 19 Japanese male heterosexuals, 5 Japanese female heterosexuals and 23 Thai female heterosexuals. Of these 36 were clade B and 35 were clade E and one case showed positive PCR results for both B and E primers. Almost all male Japanese hemophiliacs and homosexuals in our sample have clade B, while the female Thai heterosexuals have clade E, irrespective of the year of isolation. As for Japanese male heterosexuals, through 1993, clade B was predominant but since 1994, the predominate clade switched to clade E. Although the number of Japanese female heterosexuals in our sample is small, clade B was isolated in 2 cases even after 1994.

Female↗