Biomedical subjects

S Kawamoto

Publications and source records attributed to S Kawamoto.

At least 145 records · Page 8Linked to original sources

PubMed1997

Enhancement of cell-mediated immunity against HIV-1 induced by coinnoculation of plasmid-encoded HIV-1 antigen with plasmid expressing IL-12.

Previous investigations have demonstrated that CTL may play an important role in suppressing the disease progression of HIV infection. In this study, we inoculated mice with IL-12 expression plasmid together with plasmid-encoding HIV-1 envelope to enhance CTL activity by activating a Th1-type response. The results of delayed-type hypersensitivity using the footpad swelling response and of CTL activity clearly showed that HIV-1-specific cell-mediated immunity was enhanced by inoculation of the IL-12 expression plasmid. Quantitation of cytokine in the sera of IL-12-inoculated mice revealed that IFN-gamma significantly increased. The enhanced cell-mediated immunity responses were abrogated by combined administration of the IL-12 expression plasmid and neutralizing anti-IFN-gamma Ab. Together, these results suggest that enhanced virus-specific cell-mediated immunity occurred via an endogenously produced IFN-gamma by inoculation of IL-12 expression plasmid.

AIDS Vaccines↗

PubMed1997

Analysis of the glycine binding domain of the NMDA receptor channel zeta 1 subunit.

In an attempt to examine glycine binding domain of the zeta 1 subunit of the mouse N-methyl-D-aspartate (NMDA) receptor channel, we constructed N-terminal or C-terminal deletion mutants of the zeta 1 subunit cDNA and expressed them in Spodoptera frugiperda cells using a baculovirus system. Analysis of binding of a glycine binding site antagonist, 5,7-[3(-3)H]dichlorokynurenate ([3H]DCKA) to the deleted zeta 1 mutants provided the first direct experimental evidence that the regions of N-terminal 282 and C-terminal 102 amino acid residues do not significantly affect glycine binding, and that both the region of approximately 260 amino acid residues preceding the putative transmembrane segment M1 and the region between the segments M3 and M4 are required to form the glycine binding domain.

Animals↗

PubMed1997

Dissection of the promoter/operator region and evaluation of N-acylhomoserine lactone mediated transcriptional regulation of elastase expression in Pseudomonas aeruginosa.

In Pseudomonas aeruginosa, expression of the lasB gene which codes for the metalloprotease, elastase, depends on small diffusible N-acylhomoserine lactones. lasB expression is regulated through the interactions of N-3-oxododecanoyl-L-homoserine lactone and N-butanoyl-L-homoserine lactone with the transcriptional activators LasR and VsmR(RhlR), respectively. To investigate lasB expression further, we first located the transcriptional start site to a position 141 bp upstream from the translational start site. Using this information, we constructed a series of plasmids containing consecutive 5' deletions of the upstream region of lasB fused to a promoterless chloramphenicol acetyltransferase reporter gene. The results obtained indicate that three regions are required for efficient transcription of lasB; a 35 bp palindromic sequence located at +26 to +60 bp upstream from the translation start site, and two regions located upstream of the transcription start site, at -135 to -85 bp and -63 to -26 bp, respectively. Deletion of the latter region results in the loss of both N-butanoyl-L-homoserine lactone- and N-3-oxododecanoyl-L-homoserine lactone-mediated stimulation of lasB expression and provides further support for the role of this operator site as a target for either or both LasR and VsmR.

Bacterial Proteins↗

PubMed1997

Immunomodulatory effects of a plasmid expressing B7-2 on human immunodeficiency virus-1-specific cell-mediated immunity induced by a plasmid encoding the viral antigen.

B7 co-stimulation is essential for activating resting T cells following antigen recognition by the T cell receptor. To determine whether B7 has adjuvant activities on human immunodeficiency virus type-1 (HIV-1)-specific immunity induced by inoculation of a plasmid encoding HIV-1 env and rev (DNA vaccine), B7-1 and B7-2 expression plasmids were co-inoculated with the DNA vaccine. The delayed-type hypersensitivity response and cytotoxic T lymphocyte (CTL) activity were significantly enhanced when B7-2 expression plasmid was co-inoculated with the DNA vaccine, but were unaffected when the B7-1 expression plasmid was used with the vaccine instead. The immunological response enhanced by B7-2 decreased below the level of mice immunized with the DNA vaccine in combination with CTLA4Ig, an inhibitor of the B7/CD28 co-stimulatory signal, suggesting that this signal is critical for the enhanced response induced by co-inoculation of the DNA vaccine and B7-2 expression plasmid. This enhancement appeared to occur via an interferon-gamma (IFN-gamma)-dependent mechanism, as combined administration of the B7-2 plasmid and neutralizing anti-IFN-gamma antibody abrogated the virus-specific cell-mediated immunity. These results suggest that this gene-based co-inoculation strategy using HIV-1 viral antigen and B7-2 co-stimulatory molecule could be a powerful means of combating HIV-1 infection.

AIDS Vaccines↗

PubMed1997

Human immunodeficiency virus type-1-specific immune responses induced by DNA vaccination are greatly enhanced by mannan-coated diC14-amidine.

Use of mannan-coated N-t-butyl-N'-tetradecyl-3-tetradecylamino-propionamidine (diC14-amidine) as an adjuvant for a DNA vaccine encoding glycoprotein 160 of human immunodeficiency virus type-1 (HIV-1) enhanced the antigen-specific immune responses. The role of interferon-gamma (IFN-gamma) and interleukin-12 in the mechanism of adjuvant action was also evaluated. Coating of diC14-amidine with mannan significantly augmented the HIV-specific delayed-type hypersensitivity reaction induced by the immunogenic DNA. HIV-1-specific cytotoxic T lymphocyte activity was also markedly enhanced by the mannan-diC14-amidine cocktail. An immunomodulatory effect of this cocktail was inhibited by treatment with anti-IFN-gamma monoclonal antibody in vivo, which suggests that IFN-gamma plays an important role in inducing cell-mediated immunity by the DNA vaccine containing this adjuvant. The results of both antigen-specific immunoglobulin isotype analysis and cytokine measurement showed that the immunogenic DNA incorporated into mannan-coated diC14-amidine elicits Th1-biased immune responses.

AIDS Vaccines↗

PubMed1997

Correlation of expression levels of P-glycoprotein with resistance to adriamycin in a renal adenocarcinoma cell line.

We have demonstrated that low-level expression of P-glycoprotein (PGP), detectable by reverse transcriptase polymerase chain reaction (RT-PCR) assay and flow cytometric assay, is an important factor in multidrug resistance (MDR) in ACHN cancer cells. In this study, we established a subline highly resistant to adriamycin (ACHN/ADM) from ACHN cells, and determined the correlation between PGP levels and MDR levels using ACHN/ADM cells and their parent ACHN cells. The ACHN/ADM cells showed overexpression of PGP, and sensitivity to antitumor agents was lower than that found in ACHN cells. Intracellular accumulation of ADM in ACHN/ADM cells was approximately half the amount of its accumulation in ACHN cells. Sensitivity to ADM in ACHN/ADM cells was enhanced by chemosensitizers with an increase in intracellular ADM accumulation. These results indicate that PGP levels correlate with MDR levels and suggest that chemotherapy using chemosensitizers might be effective in the treatment of renal cancers with overexpression of PGP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

Molecular and functional analysis of the ribosomal L11 and S12 protein genes (rplK and rpsL) of Streptomyces coelicolor A3(2).

A RelC deletion mutant, KO-100, of Streptomyces coelicolor A3(2) has been isolated from a collection of spontaneous thiostrepton-resistant mutants. KO-100 grows as vigorously as the parent strain and possesses a 6-bp deletion within the rplK, previously termed relC. When the wild-type rplK gene was propagated on a low-copy-number vector in mutant KO-100, the ability to produce ppGpp, actinorhodin and undecylprodigiosin, which had been lost in the RelC mutant, was completely restored. Allele replacement by gene homogenotization demonstrated that the RelC mutation is responsible for the resistance to thiostrepton and the inactivation of ppGpp, actinorhodin and undecylprodigiosin production. Western blotting showed that ribosomes from the RelC mutant KO-100 contain only one-eighth the amount of L11 protein found in ribosomes of the parent strain. The impairment of antibiotic production in KO-100 could be rescued by the introduction of mutations that confer resistance to streptomycin (str), which result in alteration of Lys-88 in ribosomal protein S12 to Glu or Arg. No accompanying restoration of ppGpp synthesis was detected in these RelC str double mutants.

Alleles↗

PubMed1997

Molecular analysis of the ribosomal L11 protein gene (rplK = relC) of Streptomyces griseus and identification of a deletion allele.

The rplK (= relC) gene, which codes for ribosomal protein L11, was cloned from Streptomyces griseus IFO13189 using a screening procedure based on polymerase chain reaction amplification of a gene segment that subsequently allowed the isolation of the complete gene from a gene library. rplK lies between the nusG gene, encoding a protein involved in antitermination of transcription, and the rplA gene, which encodes the ribosomal protein L1. Comparison of the rplK gene sequences of the wild-type strain and the presumed relC mutant strain 3-3 (originally isolated as a thiopeptin-resistant isolate) revealed a 12-bp deletion within the rplK gene from the mutant, flanked by a 4-bp repeat sequence in the corresponding region in the wild type. When the wild-type rplK gene was propagated on a low-copy-number vector in the relC mutant 3-3, the ability to produce guanosine 5'-diphosphate 3'-diphosphate, streptomycin, and submerged spores was completely restored to parental levels. The impaired ability to form aerial mycelium was, however, unaffected. Western blotting analysis showed that the ribosomes from the relC mutant 3-3 incorporate the mutant L11 protein normally, although the level of incorporation is approximately one-third that of the wild-type L11 protein in ribosomes of the parent strain. Propagation of the mutant rplK gene in the wild-type strain resulted in marked defects in growth, streptomycin production, and aerial mycelium formation, indicating that the mutant L11 protein exerts certain negative effects in the cells.

Alleles↗

PubMed1997

Detection of Theileria sergenti schizonts in bovine lymph node.

The growth of Theileria sergenti schizonts in bovine lymph nodes was examined by experimental infection. Six naive Holstein calves were inoculated with a sporozoite stabilate into the superficial cervical and subiliac lymph nodes. Biopsy samples from the inoculated calves were collected every 24 h for 10 days. Histological examination demonstrated the schizont of T. sergenti on day 4 post-inoculation. The growth of schizonts in the lymph node was observed on days 4-8 post-inoculation. Electron microscopic observation disclosed that the core of the schizont has a high density central core surrounded by numerous electron-dense spherules.

Animals↗

PubMed1997

Arginine-481 mutation abolishes ligand-binding of the AMPA-selective glutamate receptor channel alpha1-subunit.

Arginine-481 is located in the putative agonist-binding region preceding the putative transmembrane segment M1 of the alpha1-subunit of the AMPA-selective glutamate receptor (GluR) channel. This amino acid is completely conserved among GluR proteins. A site-directed mutagenesis study using a baculovirus expression system showed that substitution of glutamate, glutamine and lysine for arginine-481 of the recombinant alpha1-subunit protein abolishes binding to [3H]AMPA completely. The present study provides the first direct experimental evidence that the conserved charged arginine-481 residue is essential, directly or indirectly, for the acquisition of ligand-binding activity by the receptor protein.

Animals↗

PubMed1997

Synthetic peptide from the V3 loop consensus motif with a potent anti-HIV activity inhibits ristocetin-mediated vWF-GPIb interaction.

The V3 loop consensus motif. Arg-Gly-Pro-Gly-Arg-Ala-Phe-Val-Thr-Ile (HIV-1 IIIB), inhibits an interaction of HIV with CD4-positive lymphocytes. Recently, both proline-rich peptides and peptides containing proline-glycine loops (beta-turns) form a complex with ristocetin dimers. These peptides interact with ristocetin-loaded platelet membrane glycoprotein (GP) Ib and act as inhibitors of von Willebrand factor (vWF)-GPIb interaction by preventing the subsequent formation of ristocetin dimer bridges. The Pro-Gly sequence is also present in the V3 loop consensus motif, Arg-Gly-Pro-Gly-Arg-Ala-Phe-Val-Thr-Ile (HIV-1 IIIB). In this report, we have evaluated the effect of the HIV-1 IIIB peptide on vWF binding to GPIb. This peptide only inhibited vWF binding to GPIb as well as platelet aggregation in the presence of ristocetin while it had no effect on botrocetin-mediated vWF interaction with platelets. The peptide inhibited a binding of anti-vWF monoclonal antibody (RG-46) to immobilized vWF. Furthermore, ristocetin inhibited the binding of HIV-1 IIIB peptide to immobilized CXC-chemokine receptor-4 (CXCR-4) peptide. These results indicate that ristocetin may prevent HIV infection and would be useful a tool to understand the mechanism of HIV tissue tropism and infection.

Amino Acid Sequence↗

PubMed1997

DNA vaccination followed by macromolecular multicomponent peptide vaccination against HIV-1 induces strong antigen-specific immunity.

The induction of a strong and long-lasting immunity characterized by both a humoral and cell-mediated immune (CMI) response is one of the most important considerations in developing an effective HIV vaccine. In previous studies, we have independently developed both DNA vaccine and macromolecular multicomponent peptide vaccine (VC1) candidates. In the present study, we attempted to optimize the vaccination protocol using mice, guinea pigs, rabbits and Macaca fuscata monkeys. Repeated vaccination with VC1 induced a substantial level of multivalent antibodies which neutralized various HIV-1 strains, as determined using a p24 inhibition assay. On the other hand, repeated immunization with DNA vaccine induced and sustained high levels of cytotoxic T lymphocytes (CTLs). In addition, when DNA vaccination was followed by multicomponent peptide vaccination, levels of both humoral immunity and CMI increased, and this effect continued for at least 10 months. These data clearly demonstrate that for inducing HIV-1 specific immunity, immunization with DNA vaccine followed by VC1 boosting produces better results than immunizing with either vaccine alone.

AIDS Vaccines↗

PubMed1997

Role of radiosurgery in the management of cavernous sinus meningiomas.

OBJECTIVE: To provide our early experience and philosophy in the utility of radiosurgery in the management of cavernous sinus meningiomas. METHODS: Twenty-five consecutive cases with cavernous sinus meningiomas treated between 1990 and 1995 were reviewed. Three cases were treated with gamma-knife radiosurgery, 15 with preceding surgery and gamma knife, 7 with surgery. Mean follow-up following radiosurgery and surgery were 34.8 and 25.4 months, respectively. RESULTS: The 5-year actuarial tumor control rate following radiosurgery was 85.7% and tumor remission rate was 61.4%. Permanent neurological deterioration after radiosurgery was seen in 1 case (5.9%), whereas newly developed or worsened neurological deficits permanently persisted in 59.1% of patients after surgery. There was a clear correlation between surgical radicality and postoperative morbidity rate. CONCLUSIONS: Gamma-knife radiosurgery is a valuable addition to surgical removal in the treatment of cavernous sinus meningiomas. Combination of non-radical resection and subsequent radiosurgery is recommended to improve treatment-associated morbidity.

Adult↗

PubMed1997

[Analysis of cases allowed to cease erythromycin therapy for diffuse panbronchiolitis--comparative study between patients with cessation of the therapy and patients continuing the therapy].

We investigated the effect of erythromycin (EM) in patients with diffuse panbronchiolitis (DPB) who were divided into 2 groups, the short term group with 8 patients who were treated for at least 2 years and the long term group with 7 patients who were treated for more than 3 years. Each mean value of %VC, FEV1.0, FEV1.0% and PaO2 two years after administration to these patients was improved than before administration of EM, with the exception of PaO2 in the long term group. There was no change in %VC, FEV1.0, FEV1.0% or PaO2 in each group between one year after the therapy and thereafter, with the exception of the fact that FEV1.0% in the short term group, except patients restarting EM therapy, 2 years after the therapy was significantly higher than in the long term group. One patient was readministered EM because of recurrence of DPB after cessation of EM therapy, whose %VC, FEV1.0 and PaO2, but not FEV1.0%, one year after the therapy were increased in those before the therapy. The Neutrophil proportion in the bronchoalveolar lavage (BAL) fluid in this patient was still high after the therapy (94.5%), while that in the patients with cessation of the therapy was improved to the level of less than 8%. Neutrophil proportion in BAL fluids in the patients with continuation of the therapy revealed a high or low level after the therapy. These results suggest that the patients, whose %VC, FEB1.0% and PaO2 were improved and whose proportion of neutrophils in BAL fluid reduced to a normal level compared with those before EM therapy, can be allowed to cease therapy after 2 years or more of EM therapy.

Adolescent↗

PubMed1997

High prevalence of Borna disease virus infection in healthy sheep in Japan.

Previous seroepidemiological and molecular epidemiological studies of Borna disease virus (BDV) showed considerably high rates of infection in horses, cattle, cats, and humans in Hokkaido, Japan. Here, we further demonstrate high rates of specific antibodies to BDV and BDV RNA in peripheral blood mononuclear cells (PBMCs) from healthy sheep bred on the same island. The BDV prevalences by immunoblotting and/or reverse transcriptase PCR were 0% (0 of 19) in newborns (<1 month old), 51.7% (15 of 29) in lambs (1 to 6 months old), and 36.7% (11 of 30) in adults (>2 years old). Among animals positive for BDV, 60% of lambs and 45.5% of adults contained BDV RNA in PBMCs while 46.7% of lambs and 90.9% of adults contained specific antibodies to BDV. Thus, it is suggested that virus replication in the blood, as observed in lambs, is usually reduced in adulthood by raising immune responses to BDV.

Animals↗

PubMed1997

Thoracoabdominal aorta in Marfan syndrome: MR imaging findings of progression of vasculopathy after surgical repair.

PURPOSE: To determine the natural history of vasculopathy of the thoracoabdominal aorta in patients with Marfan syndrome after composite graft repair of the aortic root. MATERIALS AND METHODS: A total 224 magnetic resonance (MR) images obtained in 48 patients with Marfan syndrome over a period of 2.3-9.4 years (mean, 5.0 years) were retrospectively reviewed. On each image, the diameter of the thoracoabdominal aorta was measured and the presence of dissection or major peripheral artery aneurysms was determined. RESULTS: In 31 (65%) of the 48 patients, no statistically significant change (3 mm or less increase in diameter) in the diameter of the aorta occurred during the study (group 1); in the remaining 17 (35%) patients, a significant change occurred (greater than 3 mm increase) (group 2). The mean initial diameter of the native aorta was slightly larger in group 2 (mean, 27 mm +/- 8 [standard deviation]) than in group 1 (mean, 23 mm +/- 6). In group 1, the mean rate of dilation was 0.07 mm/y +/- 0.2; in group 2, the rate was 2.3 mm/y +/- 3.3. Two patients with aortic dissection were in group 1, whereas 14 such patients were in group 2 (P < .001). Aneurysms that involved major peripheral arteries were present in four (13%) of the 31 group 1 patients and in 12 (71%) of the 17 group 2 patients (P < .001). Surgical intervention was necessary in two group 1 patients and in 14 group 2 patients (P < .001). CONCLUSION: A subset of patients with Marfan syndrome manifested multiple forms of vasculopathy, including progressive aortic dilation, dissection, and peripheral artery aneurysm after composite aortic graft repair of the ascending aorta. Patients with these characteristics merit more frequent MR follow-up since further surgery was often necessary in these individuals.

Adolescent↗

PubMed1997

Ruptured dissecting aneurysm as a cause of subarachnoid hemorrhage of unverified etiology.

BACKGROUND AND PURPOSE: The clinical features of "aneurysmal" subarachnoid hemorrhage (SAH) of angiographically unverified etiology were reviewed to clarify the incidence and natural history of dissecting aneurysms as the hemorrhagic source of SAH. METHODS: We reviewed 30 patients with SAH of unverified etiology in whom initial CT scan showed a diffuse or anteriorly distributed subarachnoid blood clot. Ten of the patients had stenotic or occlusive lesions (SOCL) on initial angiography, and these were the main focus of this study. RESULTS: Among the 10 patients with SOCL on initial angiography, the lesions were located on the anterior circulation in 6 and on the posterior circulation in 4. Ruptured dissecting aneurysms were confirmed by exploratory surgery or autopsy in 6 patients. Subsequent rupture occurred in 6 of the 10 patients (60%), and all 6 of these patients died as a result. CONCLUSIONS: The incidence (6/30) of dissecting aneurysms as the cause of SAH of unverified etiology was unexpectedly high, especially when initial angiography disclosed SOCL (6/10). The moribund patients with SOCL showed a high rate of rebleeding, and the untreated recurrent hemorrhages were fatal. Further MRI study is indicated for these patients to demonstrate the intramural hematoma. Compared with the devastating mortality caused by the subsequent ruptures, the extent of surgical morbidity was minor. Surgical intervention could therefore be justified when the following neuroradiological findings are present: (1) SOCL evident on angiography, (2) distribution of SAH on CT compatible with the location of the SOCL, and (3) intramural hematoma on MRI in the same region as the SOCL.

Adult↗

PubMed1997

Orthotopic liver transplantation for adult-onset type II citrullinaemia.

Citrullinaemia is a rare autosomal recessive disorder due to a deficiency of argininosuccinate synthetase (ASS). While the clinical course of the adult onset form (Type II) is unpredictable, many patients undergo sudden deterioration with progressive cerebral oedema. Two patients with Type II citrullinaemia were referred for liver transplantation. One patient was successfully transplanted, and his plasma citrulline level decreased from 300 to 69 mumol/l (normal range 20-60 mumol/l); Fisher's ratio increased to a normal range within 24 h of transplantation. The other patient died from cerebral oedema, despite Optimal pharmacological measures, while awaiting a suitable donor organ. Dietary and pharmacological treatment is vital before liver transplantation. The level of serum arginine requires regulation, as it can rise secondary to citrullinaemia in Type II disease. An immunocytochemical study of the liver in both patients showed a clustered distribution of ASS which is associated with a dismal prognosis compared with patients who have a homogenous distribution. Distribution of ASS was normal in the transplanted liver. Liver transplantation is effective therapy for adult-onset Type II citrullinaemia. A clustered pattern of ASS distribution in a liver biopsy is a significant feature to activate early referral for liver transplantation.

Adult↗