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Biomedical subjects

T Tsujimura

Publications and source records attributed to T Tsujimura.

At least 19 recordsLinked to original sources
PubMed2006

Intraperitoneal injection of oxygenated perfluorochemical improves the outcome of intraportal islet transplantation in a rat model.

A 50% to 75% early graft loss upon engraftment has been suggested to in intraportal islet transplantation (IPIT). Hypoxia in the portal vein contributes to graft loss in immediately posttransplantation. Herein we examined the effect on the outcome of IPIT of intraperitoneal oxygenated perfluorochemical (PFC) as an oxygen carrier. Isolated Lewis rat islets were transplanted into the portal vein of a chemically induced diabetic syngeneic rat. First, 1500 IEQ was determined to be the optimal dose in this study. When oxygenated PFC (group 1) was intraperitoneally injected following IPIT of 1500 IEQ, the success rate of transplantation was 5/6, in contrast to 1/6 when PFC with no oxygen was injected (group 2) and 1/6 in IPIT without PFC, respectively. The area under the glucose profile curve on intraperitoneal glucose tolerance tests on posttransplant day 28 in group 1 was significantly smaller than that for group 2. In conclusion, intraperitoneal oxygenated PFC improved the outcome of IPIT.

Animals↗
PubMed2004

Neuroendocrine differentiation of periodic-acid Schiff and Alcian blue-negative signet-ring cell-like cells and tubular adenocarcinoma cells within a gastric cancer.

A case of a Borrmann type 2 advanced gastric cancer with endocrine differentiation is described. Histologically, the cancer was either composed of cells arranged in a tubular pattern or formed solid nests of various sizes. The tubular pattern was composed of a moderately differentiated tubular adenocarcinoma. The histology showed partial carcinoid tumor-like features. Cancer cells inside solid nests had a signet-ring cell-like appearance. Periodic-acid Schiff (PAS) staining was positive in the cytoplasm of a few of the cells found in the tubular pattern and in the mucus in some lumens and on the apical surface of cells in some lumens, but PAS did not stain cancer cells in the solid nests. Neither cancer cells nor mucus in the lumens were stained with alcian blue. All cancer cells were strongly positive for Grimelius silver stain, and most of the cancer cells stained positively for chromogranin A. Electron microscopic examination showed electron dense neuroendocrine granules in the cytoplasm of cancer cells. Cancer cells were stained positively for pancytokeratin, cytokeratin 8/18 and carcinoembryonic antigen. Muc 1 mucin glycoprotein staining was positive along the cell surfaces of cancer cells, but Muc 2, 5AC and 6 stainings were negative, although Muc 3 stained positively in the cytoplasm of a few cancer cells. The present case is a gastric tubular adenocarcinoma with Muc 1-positive, neutral- and acid mucin-negative signet-ring cell-like cells, which is associated with neuroendocrine differentiation.

Adenocarcinoma↗
PubMed2003

Resuscitation of the ischemically damaged human pancreas by the two-layer method prior to islet isolation.

A two-layer cold storage method (TLM) allows sufficient oxygen delivery to pancreata during preservation and resuscitates the viability of ischemically damaged pancreata. This study determined the effect of additional preservation of ischemically damaged human pancreata by the TLM before islet isolation. Human pancreata were procured from cadaveric organ donors and preserved by the TLM for 3.2 +/- 0.5 hours (mean +/- SEM) at 4 degrees C after 11.1 +/- 0.9 hours of cold storage in University of Wisconsin solution (UW) (TLM group), or by cold UW alone for 11.0 +/- 0.3 hours (UW group). Islet isolations of all pancreata were performed using the Edmonton protocol. Islet recovery and in vitro function of isolated islets were significantly increased in the TLM group compared with the UW group. In the metabolic assessment of human pancreata, ATP levels were significantly increased after the TLM preservation. This study showed that additional short-term preservation by the TLM resuscitates the viability of ischemically damaged human pancreata before islet isolation, leading to improvements in islet recovery and in vitro function of isolated islets.

Adenosine↗
PubMed2003

Improvement of pancreatic islet isolation outcomes using glutamine perfusion during isolation procedure.

During procurement, isolation, and transplantation, islets are exposed to high levels of oxidative stress triggering a variety of signaling pathways that can ultimately lead to cell death. Glutamine is an important cellular fuel and an essential precursor for the antioxidant glutathione. The aim of this study was to examine the role of intraductal glutamine administration in facilitating recovery of isolated rat islets from pancreases subjected to a clinically relevant period of warm ischemia. Islets were isolated in Sprague-Dawley (SD) rats (n = 18 per group). Pancreata in groups 1 and 2 were procured immediately while groups 3 and 4 were subjected to 30-min warm ischemia. Groups 2 and 4 were treated intraductally with 5 mM glutamine prior to pancreatectomy. Exposure to 30-min warm ischemia significantly reduced islet yield [groups 1 & 2 (nonischemia): 503 +/- 29 islets/rat vs. groups 3 & 4 (ischemia): 247 +/- 26 islets/rat; p < 0.05]. Intraductal glutamine treatment significantly improved islet yield when pancreata were subjected to 30-min warm ischemia [144 +/- 16 islets/rat without glutamine (group 3) vs. 343 +/- 36 islets/rat with glutamine (group 4), p < 0.05]. Glutamine also significantly improved islet viability (values were 50 +/- 4% in group 4 vs. 27 +/- 3% in group 3, p < 0.05). Similarly, glutathione (reduced) levels were significantly elevated in both glutamine-treated groups; however, this increase was greatest in tissues exposed to ischemia (2.76 +/- 0.04 nmol/mg protein in group 4 vs. 1.66 +/- 0.04 nmol/mg protein in group 3, p < 0.05). Intraductal glutamine administration considerably improves the islet yield, viability, and augments endogenous glutathione levels in pancreata procured after a clinically relevant period of ischemia. Intraductal administration of glutamine at the time of digestive enzyme delivery into the harvested pancreas may represent a simple yet effective tool to improve islet yields in clinical isolations.

Animals↗
PubMed2002

Interleukin-18 and interleukin-12 synergistically inhibit osteoclastic bone-resorbing activity.

The effect of interleukin (IL)-18 on osteoclastic bone-resorbing activity was investigated in vitro. Osteoclast-enriched cells, about 70% of which were tartrate-resistant acid phosphatase (TRAP)-positive, were cultured on dentine slices, and then the total volume of resorption pits on each dentine slice was measured as bone-resorbing activity. When the effects of IL-18 alone at 1, 10, 100, and 1000 ng/mL were examined, bone-resorbing activity was significantly reduced only at 1000 ng/mL, by about 50%. However, IL-18 plus IL-12 (10 ng/mL each) reduced bone-resorbing activity by about 70%, whereas IL-12 alone had no significant effect. When the concentration of interferon (IFN)-gamma in the medium was measured, IL-18 or IL-12 was found to increase it slightly, and the combination of these two cytokines synergistically increased it. The inhibitory effect of the combination of the two cytokines was completely abolished by the addition of an anti-IFN-gamma neutralizing antibody to the medium, but IFN-gamma by itself did not inhibit osteoclastic bone resorption. IL-18 alone or in combination with IL-12 did not affect the number of TRAP-positive cells in culture of osteoclast-enriched cells. Osteoclasts prepared from osteoclast-enriched cells expressed mRNAs of IL-18 receptor, MyD88, and cathepsin K. Furthermore, IL-18 receptor protein was detected on the cell surface of osteoclasts. The present results indicate that the combination of IL-18 and IL-12 synergistically inhibits osteoclastic bone-resorbing activity, suggesting that IFN-gamma participates in the mechanism underlying this inhibition.

Animals↗
PubMed2001

Histamine N-methyltransferase regulates histamine-induced phosphoinositide hydrolysis in guinea pig cerebellum.

We report here that the dose-response curve of the histamine-stimulated phosphoinositide hydrolysis in the guinea pig cerebellar slices was shifted to the left when the slices were pretreated with SKF 91488 (100 microM), a specific inhibitor of histamine N-methyltransferase (HMT). In contrast, the pretreatment of the cerebellar slices with aminoguanidine (100 microM - 1 mM), an inhibitor of diamine oxidase, had no effect on histamine-induced phosphoinositide hydrolysis. HMT mRNA was expressed abundantly in cerebellum, especially in Purkinje cells. These observations suggest that HMT regulates histaminergic neurotransmission in guinea pig cerebellum more predominantly than diamine oxidase in histamine degradation.

Animals↗
PubMed2001

A role of interferon-gamma (IFN-gamma) in tumor immunity: T cells with the capacity to reject tumor cells are generated but fail to migrate to tumor sites in IFN-gamma-deficient mice.

IFN-gamma-deficient (IFN-gamma-/-) mice induce potent in vitro immune responses such as anti-allo mixed lymphocyte reaction and CTL responses, whereas they often fail to exhibit in vivo immunity. Here, we investigated whether there exists a defect in tumor rejection responses and if so, which process of responses is impaired. IFN-gamma-/- and wild-type (WT) BALB/c mice were immunized with attenuated syngeneic CSA1M tumor cells. The capacity of T cells to mediate tumor protection was examined in Winn assays to assess the growth of tumor cells admixed with tumor-sensitized T cells. Splenic T cells from both groups of mice exhibited comparable levels of tumor-neutralizing activity. When portions of immunized mice were directly challenged with viable tumor cells, tumor rejection was induced only in WT mice. CD4(+) and CD8(+) T-cell infiltration were observed at the site of tumor challenge in WT mice, whereas such a T-cell infiltration did not occur in IFN-gamma-/- mice. Similarly, splenic T cells from interleukin 12-treated CSA1M-bearing IFN-gamma-/- and WT mice neutralized tumor cells at comparable efficacies in Winn assays. However, the migration of these T cells to tumor masses and the resultant interleukin 12-induced tumor regression took place in WT mice, but neither intratumoral T-cell infiltration nor tumor regression occurred in IFN-gamma-/- mice. These results indicate a critical requirement for IFN-gamma in the process of inducing T-cell migration to tumor sites rather than of generating antitumor protective T cells.

Animals↗
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

IkappaB kinase alpha is essential for mature B cell development and function.

IkappaB kinase (IKK) alpha and beta phosphorylate IkappaB proteins and activate the transcription factor, nuclear factor (NF)-kappaB. Although both are highly homologous kinases, gene targeting experiments revealed their differential roles in vivo. IKKalpha is involved in skin and limb morphogenesis, whereas IKKbeta is essential for cytokine signaling. To elucidate in vivo roles of IKKalpha in hematopoietic cells, we have generated bone marrow chimeras by transferring control and IKKalpha-deficient fetal liver cells. The mature B cell population was decreased in IKKalpha(-/-) chimeras. IKKalpha(-/-) chimeras also exhibited a decrease of serum immunoglobulin basal level and impaired antigen-specific immune responses. Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells. IKKalpha(-/-) B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-kappaB activity, but also increased turnover rate in vivo. In addition, transgene expression of bcl-2 could only partially rescue impaired B cell development in IKKalpha(-/-) chimeras. Taken together, these results demonstrate that IKKalpha is critically involved in the prevention of cell death and functional development of mature B cells.

Animals↗
PubMed2001

Syk protein-tyrosine kinase is involved in neuron-like differentiation of embryonal carcinoma P19 cells.

Syk has been implicated in activated immunoreceptors to downstream signaling events in hematopoietic cells. Here we report that Syk is expressed in neuron-like cells and involved in neuron-like differentiation of embryonal carcinoma P19 cells. Immunoblot, RT-PCR, and Northern analysis indicated that Syk is expressed in mouse brain, PC12 and P19 cells. In addition, Syk was found to be tyrosine phosphorylated during neuron-like differentiation of P19 cells. Furthermore, adenovirus-mediated overexpression of Syk induced supernumerary neurite formation and extracellular signal-regulated kinase (ERK) activation in P19 cells. These results suggest that Syk plays an important role in signaling steps leading to ERK activation in P19 cells.

Adenoviridae↗
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

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

Possible role of heat shock protein 60 in reducing ischemic-reperfusion injury in canine pancreas grafts after preservation by the two-layer method.

INTRODUCTION: Recently, results of the clinical application of the two-layer method have shown the morphologic quality of the human pancreas grafts after reperfusion to be excellent, although ischemia-reperfusion injury is related to early graft loss in pancreas transplantation. However, some reports have indicated that heat shock proteins (HSPs) have important functions in response to the stress-related events. AIM: To examine whether the two-layer method reduced ischemia-reperfusion injury in a canine pancreas autotransplantation model by investigating the expression of HSPs. METHODOLOGY: There were three experimental groups in which dogs received segmental autografts after preservation by the two-layer method using University of Wisconsin solution (UW) (group 1), simple storage in UW (group 2) for 24 hours, or no preservation (group 3). RESULTS: In group 1, pancreatic tissue perfusions were high, and pancreatic exocrine functions were well preserved after 1, 2, and 4 hours of reperfusion with low incidence of graft pancreatitis or vessel thrombosis compared with that in group 2. Moreover, ATP rapidly recovered, and HSP 60 was strongly enhanced after reperfusion in group 1. On the other hand, ATP recovery and the enhancement of HSP 60 were weak after reperfusion in group 2. CONCLUSION: The two-layer method reduced ischemia-reperfusion injury compared with UW simple storage in canine pancreas autotransplantation with a strong expression of HSP 60.

Adenosine Triphosphate↗
PubMed2001

Guinea pig histamine N-methyltransferase: cDNA cloning and mRNA distribution.

We report here the isolation of histamine N-methyltransferase (HMT) cDNA from the guinea pig brain by the polymerase chain reaction on the basis of nucleotide sequences of rat and human counterparts. Guinea pig HMT consists of 292 amino acids, with homologies of 75.6% and 79.1% to rat and human HMT, respectively. Northern blotting analysis indicated that the 1.6-kb guinea pig HMT transcript was expressed at various levels in different tissues at the following relative abundance: jejunum, brain > lung, spleen, stomach > liver, kidney. HMT mRNA localized throughout the jejunum, and it was mainly expressed in epithelial cells and in Auerbach's plexus.

Amino Acid Sequence↗
PubMed2001

Developmental changes in the fine structure and histochemical properties of mucous cells in the parotid gland of the infant Japanese macaque.

Mucous cells have been known to occur in the terminal portions of the parotid gland in a few species of mammals during a limited period of their development. The aim of this study was to examine the occurrence and features of mucous cells in the parotid gland of the infant Japanese macaque. Light microscopy revealed that mucous cells in the macaque parotid gland were present in the terminal clusters and acini at postnatal day 15, were less prevalent at day 30, and continued to decrease in number over 3 months. Mucous cells were no longer recognized in the parotid gland in 6-month-old macaques. Electron microscopy showed that the mucous cells contained electron-lucent secretory granules and bipartite or tripartite secretory granules. By 3 months of age, there was a scarcity of mucous cells and a concomitant increase in transitional cells. These transitional cells were intermediate in structure between mucous and serous cells, and contained three types of granules: electron-lucent, bipartite or tripartite, and electron-dense. None of the cells showed apoptotic figures. Lectin histochemistry indicated that the mucous cells in the early postnatal period had sugar residues identical in nature to those seen in the granules from mature serous cells in the glands of 3-month-old macaques. Immunohistochemistry using an antibody against human alpha-amylase showed a weakly positive reactivity in the secretory granules of the mucous cells, starting from day 15. In the transitional cells, the electron-dense granules showed a stronger immunoreactivity than either the electron-lucent granules or the heterogeneously structured granules. These results suggest that the secretory granules of mucous cells have characteristics in common with those of serous cells, and that during the transitional period the mucous granules change from the initial electron-lucent to hetorogenous forms, finally becoming the electron-dense granules. The mucous cells in the parotid gland of the juvenile Japanese macaque are therefore suggested to be converted into serous cells.

Animals↗
PubMed2001

Anorexia nervosa with ischemic necrosis of the segmental ileum and cecum.

A 41-year-old woman with long-standing anorexia nervosa showed paralytic ileus and serum creatine kinase elevation. Surgical treatment showed necrosis of the segmental ileum and cecum with perforation. She died of septic shock 3 days after the operation. Postmortem examination revealed no occlusion of the superior mesenteric artery or its main branches, and no arteriosclerotic changes. Histological examinations confirmed non-occlusive mesenteric infarction. This case suggested that necrosis of bowels might have been caused by poor blood supply due to severe malnutrition and dehydration for many years, which could be one of the fatal complications of anorexia nervosa.

Adult↗
PubMed2000

Identification of CRAM, a novel unc-33 gene family protein that associates with CRMP3 and protein-tyrosine kinase(s) in the developing rat brain.

Four members of collapsin response mediator proteins (CRMPs) are thought to be involved in the semaphorin-induced growth cone collapse during neural development. Here we report the identification of a novel CRMP3-associated protein, designated CRAM for CRMP3-associated molecule, that belongs to the unc-33 gene family. The deduced amino acid sequence reveals that the CRAM gene encodes a protein of 563 amino acids, shows 57% identity with dihydropyrimidinase, and shows 50-51% identity with CRMPs. CRAM appears to form a large complex composed of CRMP3 and other unidentified proteins in vivo. Indeed, CRAM physically associates with CRMP3 when co-expressed in COS-7 cells. The expression of CRAM is brain-specific, is high in fetal and neonatal rat brain, and decreases to very low levels in adult brain. Moreover, CRAM expression is up-regulated during neuronal differentiation of embryonal carcinoma P19 and PC12 cells. Finally, immunoprecipitation analysis of rat brain extracts shows that CRAM is co-immunoprecipitated with proteins that contain protein-tyrosine kinase activity. Taken together, our results suggest that CRAM, which interacts with CRMP3 and protein-tyrosine kinase(s), is a new member of an emerging family of molecules that potentially mediate signals involved in the guidance and outgrowth of axons.

Adaptor Proteins, Signal Transducing↗