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Biomedical subjects

Y Iwaki

Publications and source records attributed to Y Iwaki.

At least 37 records · Page 2Linked to original sources
PubMed1998

Adeno-associated virus vectors can be efficiently produced without helper virus.

The purpose of this work was to develop an efficient method for the production of adeno-associated virus (AAV) vectors in the absence of helper virus. The adenovirus regions that mediate AAV vector replication were identified and assembled into a helper plasmid. These included the VA, E2A and E4 regions. When this helper plasmid was cotransfected into 293 cells, along with plasmids encoding the AAV vector, and rep and cap genes, AAV vector was produced as efficiently as when using adenovirus infection as a source of help. CMV-driven constructs expressing the E4orf6 and the 72-M(r), E2A proteins were able to functionally replace the E4 and E2A regions, respectively. Therefore the minimum set of genes required to produce AAV helper activity equivalent to that provided by adenovirus infection consists of, or is a subset of, the following genes: the E4orf6 gene, the 72-M(r), E2A protein gene, the VA RNA genes and the E1 region. AAV vector preparations made with adenovirus and by the helper virus-free method were essentially indistinguishable with respect to particle density, particle to infectivity ratio, capsimer ratio and efficiency of muscle transduction in vivo. Only AAV vector preparations made by the helper virus-free method were not reactive with anti-adenovirus sera.

Adenoviridae↗
PubMed1997

Molecular cloning and characterization of the epididymis-specific glutathione peroxidase-like protein secreted in the porcine epididymal fluid.

The epididymis-specific glutathione peroxidase was purified from the porcine cauda epididymal fluid in order to analyze its enzymatic activity and roles in the epididymis. The purified protein was found to consist of four identical 23 kDa subunits. The complementary DNA encoding the 23 kDa subunit was cloned from the cDNA library of the porcine proximal caput epididymis, only where the 23 kDa subunit is expressed. Although the selenocysteine codon (TGA) is contained in the cDNA of the other cytosolic type of glutathione peroxidases, it is replaced by cysteine codon (TGT) in the 23 kDa subunit cDNA, similarly to the results previously obtained for cDNAs encoding the epididymis-specific form of the secreted glutathione peroxidases of mouse, rat and monkey. By the direct analysis of the selenium, the purified protein was proved to contain no selenium atom in the molecule. The activities of the purified epididymis-specific glutathione peroxidase toward hydrogen peroxide or organic hydroperoxides were by far lower than the activity of cytosolic selenium-dependent glutathione peroxidase (less than 0.1%). In addition, the concentration of glutathione in the porcine epididymal fluids was about 20 microM, which is much lower than the optimal concentration for the glutathione peroxidase activity of the purified protein. These results strongly suggest that this protein is enzymatically quiescent at least in the porcine epididymal fluid. An immunocytochemical study showed that this protein was found to bind to the acrosomal region of the epididymal sperm and to disappear during the acrosome reaction. Furthermore, this protein significantly retarded the acrosome reaction induced in vitro. The possibilities have been discussed that it protects sperm from the premature acrosome reaction and maintains sperm fertilizing ability in the epididymis.

Amino Acid Sequence↗
PubMed1997

2,3-Dihydro-5-hydroxy-2,2-dipentyl-4,6-di-tert-butylbenzofuran: design and evaluation as a novel radical-scavenging antioxidant against lipid peroxidation.

To develop a novel potent radical-scavenging antioxidant, the ideal structure of a phenolic compound was designed considering the factors that determine antioxidant potency. 2,3-Dihydro-5-hydroxy-2,2-dipentyl-4, 6-di-tert-butylbenzofuran (BO-653) was thus synthesized and its antioxidant activity was evaluated against lipid peroxidations in vitro. The electron spin resonance study showed that the phenoxyl radical derived from BO-653 was more stable than alpha-tocopheroxyl radical. BO-653 reduced alpha-tocopheroxyl radical rapidly, but alpha-tocopherol did not reduce the phenoxyl radical derived from BO-653. However, the chemical reactivity of BO-653 toward peroxyl radical was smaller than that of alpha-tocopherol. This was interpreted as the steric effect of bulky tert-butyl groups at both ortho positions which hindered the access of peroxyl radical to the phenolic hydrogen. However, the tertbutyl substituents increased the stability of BO-653 radical and also lipophilicity, and its antioxidant potency against lipid peroxidation in phosphatidylcholine liposomal membranes was superior to that of alpha-tocopherol. Ascorbic acid reduced the phenoxyl radical derived from BO-653 and spared BO-653 during the oxidation of lipid in the homogeneous solution. On the other hand, ascorbic acid did not spare BO-653 in the oxidation of liposomal membranes. It was concluded that BO-653 is a potent novel radical-scavenging antioxidant.

Antioxidants↗
PubMed1997

Hydroxyapatite in revision of total hip replacements with massive acetabular defects: 4- to 10-year clinical results.

Hydroxyapatite (HA) granules of 100 to 300 microm, 0.9 to 1.2 mm and 3.0 to 5.0 mm were mixed in a ratio of 10:45:45 and packed into massive bone deficiencies in revision operations for total hip arthroplasty. We did not use additional graft or cup support for deficiencies of the lateral and medial wall. The procedure was carried out in 40 hips between 1986 and 1992. The radiographic spaces seen at the interface between HA and bone immediately after surgery disappeared within three months. Some spaces appeared between HA granules near the bone in the lateral part of two joints, and three sockets migrated in patients with severe segmental and cavitary deficiencies. Direct bonding of HA to bone was observed radiologically without morphological changes, except in the three joints with migration. All patients could walk without pain but the three with definite loosening needed crutches.

Acetabulum↗
PubMed1997

[The effect of tranilast on subepithelial corneal opacity after excimer laser keratectomy].

Recent studies have reported that tranilast inhibited in vitro the proliferation of keratocytes from corneal subepithelial opacities (haze) and collagen synthesis in cultured corneas after excimer laser photorefractive keratectomy (PRK). In this study 0.5% tranilast eye drops, 0.1% betametazone phosphate eyedrops, and a 0.5% tranilast base solution (control) were administered four times daily to rabbits which had undergone PRK. Weekly evaluation of the inhibitory effect of these drugs on haze began two weeks after surgery according to Fantes' classification. 0.5% tranilast suppressed haze from six weeks to thirteen weeks after PRK (p < 0.05). 0.1% betametazone phosphate showed no effect. These results suggested that 0.5% tranilast had a satisfactory therapeutic effect on haze after PRK.

Animals↗
PubMed1996

BCX-34: a novel T-cell selective immunosuppressant: purine nucleoside phosphorylase (PNP) inhibitor.

We evaluated the efficacy of a new purine nucleoside phosphorylase inhibitor, BCX-34, as an immunosuppressive agent. BCX-34 showed a complete inhibitory effect on the proliferation of T-cells in an in vitro system, whereas no influence was observed in B-cell lines. In addition, it was revealed that this inhibitory effect was not due to the suppression of interleukin-2 production. Therefore, BCX-34 might be a potentially useful drug that can be used in combination, not competition, with cyclosporine A and FK506.

Animals↗
PubMed1995

Immunoglobulin G lymphocytotoxic antibodies in clinical liver transplantation: studies toward further defining their significance.

Twenty-two consecutive liver allograft recipients, who tested positive for immunoglobulin G (IgG) lymphocytotoxicity were subjected to pretransplantation and posttransplantation immunologic monitoring of anti-donor IgG lymphocytotoxic antibody titers, total hemolytic complement activity (CH100), circulating immune complexes (CIC), and platelet counts in an effort to improve our understanding of the preformed antibody state in clinical hepatic transplantation. Ten contemporaneous liver transplant recipients whose crossmatch results were negative and who experienced severe hepatocellular damage early after transplantation were included as controls. Crossmatch test results were negative 1 day after transplantation and during the 1 month follow-up remained negative in 14 of 22 (64%) sensitized recipients, most of whom had relatively low (< or = 1:16) anti-donor IgG antibody titers before transplantation. After transplantation, this group and the control group experienced no thrombocytopenia, no increase of CIC, and a gradual increase in CH100 activity that reached normal levels within 1 week. A strong negative correlation between prothrombin time (PT) and CH100 activity in these groups of patients suggested that changes in CH100 activity (P < .0005) were tightly linked to liver synthetic function. In contrast, the crossmatch test results remained positive after transplantation in 8 of 22 (36%) sensitized recipients, all of whom had relatively high (> 1:32 to 1024) pretransplantation titers of anti-donor IgG antibodies. After transplantation these patients developed a syndrome that was characterized by decreased CH100 activity and increased CIC compared with pretransplantation levels and refractory thrombocytopenia that was associated with a 50% allograft failure rate because of biopsy-proven humoral and acute (cellular) rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Normotest and abnormal prothrombin in liver transplantation.

Postoperative changes in coagulation parameters, including the abnormal plasma prothrombin level, were studied in 95 patients who underwent liver transplantation, and the results were compared with the clinical outcome. The patients were classified into four groups: Group I had a satisfactory postoperative course, (n = 76), Group II suffered graft failure or death at 31 days or more after transplantation (n = 9); Group III suffered graft failure or death from 8 to 30 days after transplantation (n = 4); and Group IV suffered graft failure or death within 7 days of transplantation (n = 6). The Normotest, which closely reflected liver graft function, showed an increase immediately after transplantation in Group I, II, and III, but showed a marked decrease in Group IV. In patients with severe acute cellular rejection, the plasma level of abnormal prothrombin (des-gamma-carboxy prothrombin) was compared with the histology of the liver biopsy specimen. When liver graft function was good after orthotopic transplantation, the Normotest value recovered to the normal range of 70% or more. Subsequently, graft function remained good when the des-gamma-carboxy prothrombin level stayed low, whereas acute cellular rejection was indicated by an elevation of des-gamma-carboxy prothrombin was not produced by graft with early failure, the des-gamma-carboxy prothrombin level also remained low. Thus, the Normotest value and the des-gamma-carboxy prothrombin level were both useful parameters for assessing hepatic function and rejection after transplantation.

Adult↗
PubMed1994

Evaluation of sequential serum interleukin-6 levels in liver allograft recipients.

Control serum levels of IL-6 measured by ELISA in 30 healthy blood donors or volunteers were 18 +/- 34 pg/ml (mean +/- SD). Pretransplant serum levels of IL-6 in 169 adult candidates for liver transplantation were significantly higher than control in those with fulminant hepatitis (203 +/- 232 pg/ml), alcoholic cirrhosis (116 +/- 257 pg/ml), and hepatocellular carcinoma (82 +/- 105 pg/ml). With these data as background, plasma or serum levels of IL-6 were monitored in 24 adult patients after first OLT and correlated with the clinical courses and the histopathological diagnosis of rejection. Serum or plasma levels of IL-6 decreased after transplantation regardless of pretransplant value. Four patients with infection subsequently developed continuously high IL-6 values. In the 20 of 24 patients who did not have infection, significantly higher levels of IL-6 were consistently found 0-4 days before histopathological diagnosis of rejection (131 +/- 78 pg/ml) compared with significantly lower values in patients without rejection episodes (40 +/- 21 pg/ml). The elevations of IL-6 were spike shaped, did not correlate well with the histopathological grades of rejection, and were highly responsive to augmented immunosuppression. These 20 cases were classified as: group 1, no spikes of IL-6 after liver transplantation; group 2, single spike of IL-6 after liver transplantation; and group 3, multiple spikes of IL-6 after liver transplantation. The combined early and late graft loss of each group was 0% (group 1), 25% (group 2), and 67% (group 3). We conclude that daily monitored serum or plasma IL-6 levels can be a good premonitor of liver allograft rejection and also a useful predictor of long-term graft outcome.

Adult↗
PubMed1994

The characterization of cytokines in the interface tissue obtained from failed cementless total hip arthroplasty with and without femoral osteolysis.

The histologic, biochemical, and immunohistologic characteristics of the interface membranes surrounding the femoral component of failed cementless total hip arthroplasty (THA) in patients with (Group I) and without (Group II) radiographic evidence of focal endosteal erosion (osteolysis) were studied. Group I membranes had more macrophages and small particles of polyethylene debris in the membrane, but both groups had similar amounts of metal particles. A greater activity level of interleukin-1 (IL-1), tumor necrosis factor (TNF), and interleukin-6 (IL-6) was seen in the culture supernatant of the membranes from Group I than in that of Group II. Group I membranes also had more cells (macrophages, fibroblasts, and endothelial cells) that stained positively with anti-IL-6 antibody. These results suggest that IL-6, IL-1, and TNF play a role in the focal femoral osteolysis observed in patients with failed cementless hip prostheses.

Aged↗
PubMed1994

Human leukocyte antigen-class II-positive human corneal epithelial cells activate allogeneic T cells.

PURPOSE: To achieve a better understanding of the mechanism of corneal immune diseases, including corneal allograft rejection, the authors examined the potential of human corneal epithelial (HCE) cells to activate allogeneic T lymphocytes. METHODS: The mixed lymphocyte-HCE cell reaction (MLCER) was performed as follows: HCE cells from primary cultures, with or without treatment with interferon-gamma (IFN-gamma), were treated with mitomycin C and then mixed with peripheral blood lymphocytes (PBL) from normal volunteers. Triplicate cultures were incubated for 7 days. Interleukin-1-alpha (IL-1-alpha) was added to some cultures to examine its effect on MLCER: The lymphocyte responses were measured by 3H-thymidine uptake for the last 18 hours of incubation in MLCER: RESULTS: IFN-gamma-treated, HLA-class-II-bearing HCE cells stimulated allogenic lymphocytes, whereas IFN-gamma nontreated, class-II-negative HCE cells did not. The stimulation by IFN-gamma-treated HCE cells was blocked by anti-HLA class II monoclonal antibody. In addition, exogenous IL-1-alpha reduced the lymphocyte response in MLCER: This effort was inhibited by indomethacin. CONCLUSIONS: This study demonstrates that HLA-class-II-bearing HCE cells can activate allogeneic PBL by a major histocompatibility complex class II-dependent mechanism. In addition, HCE cells may regulate immune reactions, probably through prostaglandin production caused by IL-1.

Antigen-Presenting Cells↗