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Biomedical subjects

T Iwasaki

Publications and source records attributed to T Iwasaki.

At least 55 records · Page 3Linked to original sources
PubMed2001

Effectiveness and safety of mutant Escherichia coli heat-labile enterotoxin (LT H44A) as an adjuvant for nasal influenza vaccine.

The effectiveness and safety of mutant Escherichia coli heat-labile enterotoxin, LT H44A (His to Arg substitution at position 44 from the N-terminus of the A1 fragment of the A subunit) as an adjuvant for nasal influenza vaccine were examined. (1) When 0.2 microg of LT H44A, together with 0.2 microg of influenza A/PR/8/34 virus (PR8, H1N1) vaccine, was administered intranasally into BALB/c mice (twice, 4 weeks apart), anti-PR8 hemagglutinin (HA) IgA and IgG antibody (Ab) responses were induced at levels that were sufficient to provide either complete protection against infection with a small volume of PR8 virus suspension or partial protection against infection with a lethal dose of the suspension. The dose of the mutant LT and vaccine used here (0.2 microg/ 20 g doses mouse) corresponded to the estimated dose per person, i.e. 0.1 mg/10 kg body weight. (2) Using these vaccination conditions, no additional total IgE Ab responses were induced. (3) The mutant was confirmed to be less toxic than the native LT when the toxicity was analyzed either using Y1 adrenal cells in vitro (1/483 EC(50)) or by an ileal loop test. (4) One hundred micrograms of the mutant, administered intranasally or intraperitoneally into guinea-pigs (Heartley strain, 0.3-0.4 kg), caused no body-weight changes 7 days after administration, although 100 microg of the native LT administered intraperitoneally caused death in all guinea-pigs due to diarrhea within 2 days. The intranasal administration of 100 microg of the mutant resulted in almost no pathological changes in the nasal mucosa 3 days after administration. These results suggest that LT H44A, which can be produced in high yields in an E. coli culture (about 5 mg/l), could be used as one of the effective and safe adjuvants for nasal influenza vaccine in humans.

Adjuvants, Immunologic↗
PubMed2001

Evidence of macrophage foam cell formation by very low-density lipoprotein receptor: interferon-gamma inhibition of very low-density lipoprotein receptor expression and foam cell formation in macrophages.

BACKGROUND: Expression of the VLDL receptor, primarily in macrophages, has been confirmed in human and rabbit atherosclerotic lesions. The high binding affinity of the VLDL receptor for remnant particles implicates the VLDL receptor pathway in the foam cell formation mechanism in macrophages. This study investigates the effect of interferon (IFN)-gamma on VLDL receptor expression in phorbol-12-myristate-13-acetate (PMA)-treated THP-1, HL-60 macrophages, and human monocyte-derived macrophages. METHODS AND RESULTS: THP-1 cells were induced to differentiate into macrophages by PMA treatment. IFN-gamma was added to the medium, and expression of the VLDL receptor was determined. (125)I-beta-VLDL degradation study and oil red O staining were examined. In THP-1 macrophages, VLDL receptor protein expression decreased at 2 days after PMA treatment but increased at 3 days and increased up to 5 days. Scavenger receptor proteins, which were not originally present, appeared at 3 days after PMA treatment. IFN-gamma inhibited VLDL receptor expression in a dose-and time-dependent manner in macrophages. However, no inhibitory effect was observed in monocytes. Moreover, IFN-gamma receptor mRNA increased during differentiation to macrophages. (125)I-beta-VLDL degradation study and oil red O staining showed that IFN-gamma significantly inhibited foam cell formation after the uptake of beta-VLDL. LDL receptor-related protein (LRP) and LDL receptor mRNAs were not expressed in macrophages. In PMA-treated HL-60 macrophages and human monocyte-derived macrophages, IFN-gamma also inhibited VLDL receptor expression and foam cell formation by beta-VLDL. CONCLUSIONS: VLDL receptor expression is upregulated during monocyte-macrophage differentiation. IFN-gamma inhibits VLDL receptor expression and foam cell formation only in macrophages. Remnant particles induce macrophage foam cell formation through the VLDL receptor pathway.

Cell Differentiation↗
PubMed2001

Interleukin-18 up-regulates osteoprotegerin expression in stromal/osteoblastic cells.

Osteoprotegerin (OPG) and osteoclast differentiation factor (ODF) are crucial regulators of osteoclastogenesis. To determine the biological role of interleukin (IL)-18 produced by stromal/osteoblastic cells in osteoclastogenesis, we examined the effects of IL-18 on the OPG and ODF mRNA levels in these cells. When bone marrow stromal ST2 cells, osteoblastic MC3T3-E1 cells, and mouse calvarial osteoblasts were stimulated with IL-18, the expression of OPG mRNA, but not ODF mRNA, was transiently increased, its expression reaching a maximal level at 3 h after the beginning of the culture. In accordance with this observation, all these cells expressed the mRNAs of two IL-18 receptor components and MyD88, an adapter molecule involved in IL-18 signaling. Moreover, in these cells, mitogen-activated protein kinase was phosphorylated after stimulation with IL-18. These results suggest that stromal/osteoblastic cells are IL-18-responsive cells and that IL-18 may inhibit osteoclastogenesis by up-regulating OPG expression, without stimulation of ODF production, in stromal/osteoblastic cells.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Effects of intranasal administration of cholera toxin (or Escherichia coli heat-labile enterotoxin) B subunits supplemented with a trace amount of the holotoxin on the brain.

Effects of intranasal administration of cholera toxin (CT) [or Escherichia coli heat-labile enterotoxin (LT)] B subunits supplemented with a trace amount of the holotoxin, CTB* or LTB*, on the brain were examined in BALB/c mice by comparing with those of the intracerebral injection. Intracerebral injection of CTB* at doses more than 10 microg/mouse caused significant body weight loss and dose-dependent death within 7 days, with localization of conjugates of horseradish peroxidase with CTB (HRP-CTB) in the ventricular system and in the perineural space of olfactory nerves of the nasal mucosa 3 h after injection. Intracerebral injection of CTB* at doses less than 3 microg/mouse (or LTB* at doses less than 22.7 microg/mouse) did not cause any significant body weight loss for 7 days, with localization of HRP-CTB in the brain but not in the nasal mucosa. On the other hand, intranasal administration of 10 microg of CTB* caused localization of HRP-CTB in the nasal mucosa but not in the brain 3 h after administration and caused body weight loss even after 30 administrations. Neither any histological changes of brain tissues nor marked changes in serum biochemical parameters were found in mice after the 30 administrations of CTB* or LTB*. These results suggest that 0.1 microg of CTB* or LTB*, which is known to be close to the minimal effective dose as an adjuvant for nasal influenza vaccine in mice and corresponds to 100 microg per person, can be used as a safe nasal adjuvant without adversely affecting the brain.

Adjuvants, Immunologic↗
PubMed2001

Pathway of viral spread in herpes zoster: detection of the protein encoded by open reading frame 63 of varicella-zoster virus in biopsy specimens.

Reactivation of varicella-zoster virus (VZV) in the dorsal root or trigeminal ganglia causes herpes zoster. The pathway of viral spread from the ganglia to the skin and also within the skin is not yet completely understood. Histological studies have revealed that each skin lesion in herpes zoster progresses sequentially through the stages of erythema, vesicles, pustules and finally ulceration. An immunohistochemical study of the early skin lesions of herpes zoster demonstrated a high incidence of hair follicle involvement and the main localization of the virus at the isthmus. This evidence suggests that VZV initially spreads from the ganglia through myelinated nerves, which predominantly end around the isthmus of hair follicles. To further investigate the viral spread within the skin, we analyzed the sequential appearance of the immediate early proteins encoded by ORF 63 of VZV (IE63), using an anti-IE63 antibody raised by immunization of rabbits with a recombinant protein. This antibody could detect IE63 in a western blot analysis of infected cells and also in immunohistochemical analysis of the skin lesions of herpes zoster. IE63 initially appeared in the nuclei of the follicular epithelial cells and basal or parabasal epidermal cells. Later, the nuclei and cytoplasm of cells in the epidermis and hair follicles became positive. IE63 remained in the virus-infected cells even during their degeneration. When we examined the hair follicles in the early erythematous lesions, cells positive for IE63 were predominantly distributed around the isthmus. In addition, some lymphocytes around the blood vessels were also positive for IE63, but these cells were seldom positive for the structural antigen. Thus, these observations suggest that VZV arriving through myelinated nerves infects not only permissive cells, but also non-permissive cells in the involved skin of herpes zoster.

Animals↗
PubMed2001

Discordant iodine-123 metaiodobenzylguanidine uptake area reflects recovery time dispersion in acute myocardial infarction.

lodine-123 metaiodobenzylguanidine (MIBG) uptake was reported to be reduced compared to Tl-201 (Tl) in acute myocardial infarction (AMI). Within such an area, degrees of both sympathetic neural function and ischemic myocardial cell damage are considered to be greatly dispersed. These kinds of damage were reported to effect reporalization time in myocardial cells, and we evaluated our hypothesis that extension of the discordant MIBG uptake area correlates with recovery time (RT) dispersion and relate ventricular arrhythmias in AMI. MIBG and Tl images were obtained in AMI patients. Regional Tl or MIBG uptake was estimated in 9 segments of SPECT by using four-point scoring. The total score was the sum of scores in 9 SPECT segments. ATI-MIBG was calculated by subtracting the total MIBG score from the total Tl score. Corrected RT (RTc) was measured as a signal-averaged ECG. RTc dispersion was defined as the difference between maximal and minimal RTc. The patients were assigned to two groups (group A; < or = Lown 4a, group B; > or = Lown 4b) according to the results of 24-hour Holter monitoring. A positive correlation between RTc dispersion and ATI-MIBG was found. ATI-MIBG and RTc dispersion in group B were greater than those in group A. These results suggested that ATI-MIBG could be used to predict the development of malignant ventricular arrhythmias.

3-Iodobenzylguanidine↗
PubMed2001

Usefulness of indium-111-oxine-labeled leukocyte scintigraphy in diagnosis of inflammation associated with chronic aortic dissection.

BACKGROUND: Patients with chronic aortic dissection require monitoring for indications of disease progression. In present study, inflammation adjacent to associated aortic wall was evaluated by indium-111-oxine-labeled leukocyte scintigraphy, scince inflammation of the blood vessel wall often associates with progression of chronic aortic dissection. METHODS AND RESULTS: Fifteen patients with aortic dissection underwent indium-111-oxine-labeled leukocyte scintigraphy. Seven showed positive images at sites corresponding to the actual sites of the dissociated aorta. Four patients with positive images underwent surgery. Histologic examination revealed inflammatory and necrotic changes of the aortic wall. During a mean follow-up period of 2.3 years, progression of aortic dissection was observed in two of the seven patients with positive intimal imaging. CONCLUSION: Indium-111-oxine-labeled leukocyte scintigraphy may be a useful noninvasive technique to assess the persistent inflammation in patients with chronic aortic dissection.

Adult↗
PubMed2001

Detection of a coronary arterial thrombus by indium-111-oxine-labeled platelet scintigraphy.

Coronary arteriography revealed significant left anterior descending coronary artery stenosis in a 72-year-old man with a history of myocardial infarction. Stenting of the stenotic vessel was performed. Twelve hours after stenting the patient complained of chest pain but emergent coronary arteriography did not show sign of any coronary arterial stenosis. Under suspicion of coronary thrombus formation, indium-111-oxine-labeled platelet scintigraphy was performed 5 days after stenting, and revealed accumulation of indium-111-oxine in the area corresponding to the stent implantation site.

Aged↗
PubMed2001

Effect of sodium thiosulfate on cisplatin removal with complete hepatic venous isolation and extracorporeal charcoal hemoperfusion: a pharmacokinetic evaluation.

BACKGROUND: Complete hepatic venous isolation and extracorporeal charcoal hemoperfusion (HVI.CHP) can limit systemic exposure to high-dose chemotherapeutic agents when given by hepatic arterial infusion (HAI). The purpose of this study was to determine if the concomitant use of sodium thiosulfate (STS) could further expand the advantages of pharmacologic delivery of HVI.CHP for cisplatin (CDDP) during HAI chemotherapy. METHODS: CDDP (4mg/kg) was administered over 20 minutes via HAI under conditions of HVI.CHP in 14 mongrel dogs. HVI.CHP was performed for 30 minutes after initiation of HAI. During CDDP infusion, 7 dogs each received 400 mg/kg STS (a 100-fold molar ratio to CDDP) over 20 minutes via the prefilter (STS group) circuit line, while the remaining 7 dogs (controls) received no STS. Blood samples were taken serially from the prefilter circuit line (hepatic venous blood), postfilter line, and the left carotid artery (systemic blood). The free and total CDDP concentrations in these samples were determined by flameless atomic absorption spectrophotometry. RESULTS: During 20 minutes HAI of CDDP, the mean CDDP extraction ratios (ER) by CHP filter were always higher in the STS group than in the control group, regardless of the form (free or total) of CDDP. The differences between the STS and control groups in the extraction ratios of free and total CDDP were significant at all time points measured (P < .05). Consequently, systemic exposure to CDDP, as assessed by area under the time-concentration curve of total CDDP, was significantly lower in the STS group than in the control group (P < .05). CONCLUSIONS: These results indicated that concomitant STS infusion could further increase the effect of HVI.CHP on CDDP removal after HAI.

Animals↗
PubMed2001

Expression of the intermediate filament nestin in gastrointestinal stromal tumors and interstitial cells of Cajal.

It has recently been proposed that gastrointestinal stromal tumors (GISTs) originate from stem cells that differentiate toward a phenotype of interstitial cells of Cajal (ICCs). Nestin is a newly identified intermediate filament protein, and is predominantly expressed in immature cells, such as neuroectodermal stem cells and skeletal muscle progenitor cells, and tumors originating from these cells. In this study, we examined, using immunohistochemistry, the nestin expression in GISTs and ICCs to clarify the origin of GISTs. Strong immunoreactivity for nestin was observed in all 18 GISTs, and its expression was confirmed by Western blot and Northern blot analyses. In contrast, three leiomyomas and a schwannoma that developed in the gastrointestinal tract showed no apparent immunoreactivity for nestin. Among 17 mesenchymal tumors (seven leiomyosarcomas, five malignant peripheral nerve sheath tumors, and five fibrosarcomas) that occurred in sites other than the gastrointestinal tract, only two malignant peripheral nerve sheath tumors were moderately immunoreactive for nestin. Furthermore, with fluorescence double immunostaining of the normal small intestine, nestin expression was demonstrated in ICCs. These results show that nestin may be a useful marker for diagnosis of GISTs, and support the current hypothesis that GISTs are tumors of stem cells that differentiate toward an ICC phenotype.

Adult↗
PubMed2001

Krukenberg tumor from an occult appendiceal adenocarcinoid: a case report and review of the literature.

Appendiceal neoplasms with ovarian metastasis are rare. A 35-year-old woman with a left ovarian tumor underwent left salpingo-oophorectomy, partial resection of the right ovary, and a total hysterectomy. Pathological diagnosis of both ovaries was typical, Krukenberg tumor with signet-ring cells, and the second laparotomy revealed an occult appendiceal tumor to be the primary lesion. The appendix showed no evidence of malignant change of the mucosa, but the tumor cells were observed infiltrating from the basiglandular region into the underlying stroma, associated with mucocele. Although, argentaffin and argyrophil staining were negative, a few tumor cells showed immunohistochemical positivity for Chromogranin A. Accordingly, the tumor was diagnosed as adenocarcinoid rather than adenocarcinoma of the appendix. A review of the literature showed less than 40 cases of metastatic ovarian tumor from appendiceal primary, one-third of which were occult and could be detected at the second laparotomy. Cisplatin-based chemotherapy may have partial effect in the treatment of patient with adenocarcinoid tumor.

Adult↗
PubMed2001

Expression of osteopontin by exudate macrophages in inflammatory tissues of the middle ear: a possible association with development of tympanosclerosis.

Tympanosclerosis is a condition leading to a calcification process in the middle ear, and often develops after chronic inflammation of the middle ear. Since osteopontin (OPN) has been shown to participate in the pathological calcification, we here investigated whether OPN is involved in the process of calcification in tympanosclerosis. The tympanic membrane and middle ear mucosa, obtained from patients of tympanosclerosis and chronic otitis media, were histologically classified depending on the calcification degree. In hyalinized tissues with macroscopic calcification and fibrous tissues with microscopic calcification, OPN was immunohistochemically found in the calcification sites. In inflammatory tissues with microscopic calcification, OPN was also found in the calcifying foci, and many OPN mRNA-expressing cells, determined by in situ hybridization, located around their foci. Moreover, immunohistochemical double staining of OPN and CD68 showed that the OPN-expressing cells were CD68-positive, indicating these cells were macrophages. In inflammatory tissues without calcification, immunohistochemistry of CD68 and in situ hybridization of OPN mRNA revealed that most OPN mRNA-expressing cells were CD68-positive. The expression of OPN mRNA in inflammatory tissues was also shown by reverse transcriptase polymerase chain reaction. These results suggest that OPN secreted by exudate macrophages might be an important regulator in the calcification of tympanosclerosis.

Adolescent↗
PubMed2001

Laboratory culture of the myxomycetes: formation of fruiting bodies of Didymium bahiense and its plasmodial production of Makaluvamine A.

Laboratory cultures of more than 100 strains of myxomycetes were investigated, and the spore germinations of six strains were observed. The plasmodium of the myxomycete Didymium bahiense was cultured on oatmeal agar plates in a laboratory. The formation of fruiting bodies was observed in a plate culture. From the cultured organisms, a marine sponge metabolite, makaluvamine A (1), was isolated and identified on the basis of spectral data.

Animals↗
PubMed2001

Increased hepatocyte growth factor in serum in acute graft-versus-host disease.

Hepatocyte growth factor (HGF) was reported to be effective in preventing acute graft-versus-host disease (GVHD) in a murine model. We examined serum HGF concentrations in 38 patients receiving allogeneic bone marrow transplants, and investigated the relationship of serum HGF concentrations to severity of acute GVHD. More HGF was present in sera from patients with than without acute GVHD. Serum HGF correlated significantly with grade of acute GVHD. Furthermore, serum HGF correlated with serum concentrations of C-reactive protein, gamma-glutamyltranspeptidase (GTP), and aspartate aminotransferase (AST). Serum concentrations of HGF in transplanted patients without GVHD were consistently low, while those in patients with acute GVHD increased with exacerbation. We conclude that HGF was produced during induction of the GVH reaction, and probably increased as a physiological response.

Acute Disease↗
PubMed2001

The role of donor T cells for target organ injuries in acute and chronic graft-versus-host disease.

Donor T cells are crucial for target organ injury in graft-versus-host disease (GVHD). We examined the effects of donor T cells on the target organs using a parent-into-F1 model of acute and chronic GVHD. Donor T cells showed engraftment in the spleen, small intestine and liver of mice with acute GVHD, causing typical GVHD pathology in these organs. Interferon-gamma and Fas ligand expression were up-regulated, and host lymphocytes were depleted in the target organs of these mice. In contrast, donor T cells did not show engraftment in the small intestine of mice with chronic GVHD, and no GVHD pathology was observed in this organ. However, both donor T-cell engraftment and GVHD pathology were observed in the spleen and liver of chronic GVHD mice, along with the up-regulation of interleukin-4 (IL-4) and IL-10 expression plus the expansion of host lymphocytes such as splenic B cells and hepatic natural killer (NK) 1.1+ T cells. Donor anti-host cytotoxic T-lymphocyte activity was observed in spleen cells from mice with acute GVHD, but not in spleen cells from mice with chronic GVHD. Transplantation of Fas ligand-deficient (gld) spleen cells did not induce host lymphocyte depletion in target organs. These results indicate that donor T cells augment type 1 T helper immune responses and deplete the host lymphocytes from target organs mainly by Fas-mediated pathways in acute GVHD, while donor T cells augment type 2 T helper immune responses and expand host splenic B cells and hepatic NK1.1+ T cells in chronic GVHD.

Acute Disease↗
PubMed2001

Hydrogen peroxide induces Src family tyrosine kinase-dependent activation of Xenopus eggs.

Fertilization is accompanied by a rapid and transient calcium release in eggs, which is required for the onset of zygotic developmental program or 'egg activation'. Recently, it was found that Src family tyrosine kinase (SFK)-dependent phospholipase C (PLC) activity is necessary for the calcium transience in fertilized Xenopus eggs. The present study demonstrates that hydrogen peroxide (H2O2) stimulates protein-tyrosine phosphorylation in Xenopus eggs, which occurs primarily in the egg cortex of the animal hemisphere as revealed by indirect immunofluorescence study. Egg SFK was found to be upregulated by H2O2 while the SFK-specific inhibitor PP1 effectively blocked H2O2-induced tyrosine phosphorylation. As in fertilized eggs, PLCgamma, but not Shc, was tyrosine-phosphorylated in H2O2-treated eggs. H2O2 also caused inositol 1,4,5-trisphosphate (IP3) production and sustained calcium release. After limited application of H2O2, elevated SFK activity and tyrosine phosphorylation were quickly reversed. Under such conditions, eggs showed cortical contraction and dephosphorylation of p42 MAP kinase, both of which are indicative of egg activation. These egg activation events, as well as H2O2-induced IP3 production and calcium release, were sensitive to PP1 and PLC inhibitor U-73122. Together, the present study demonstrated that H2O2 can mimic, at least in part, early events of Xenopus egg activation that require an SFK-dependent PLC pathway.

Animals↗