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Biomedical subjects

Shunsuke Ohnishi

Publications and source records attributed to Shunsuke Ohnishi.

At least 19 recordsLinked to original sources
PubMed2007

Gene expression profiles of endothelial progenitor cells by oligonucleotide microarray analysis.

Among the many tissue stem or progenitor cells recently being unveiled, endothelial progenitor cells (EPCs) have attracted particular attention, not only because of their cardinal role in vascular biology and embryology but also because of their potential use in the therapeutic development of a variety of postnatal diseases, including cardiovascular and peripheral vascular disorders and cancer. The aim of this study is to provide some basic and comprehensive information on gene expression of EPCs to characterize the cells in molecular terms. Here, we focus on EPCs derived from CD34-positive mononuclear cells of human umbilical cord blood. The EPCs were purified and expanded in culture and analyzed by a high-density oligonucleotide microarray and real-time RT-PCR analysis. We identified 169 up-regulated and 107 down-regulated genes in the EPCs compared with three differentiated endothelial cells of human umbilical vein endothelial cells (HUVEC), human lung microvascular endothelial cells (LMEC) and human aortic endothelial cells (AoEC). It is expected that the obtained list include key genes which are critical for EPC function and survival and thus potential targets of EPC recognition in vivo and therapeutic modulation of vasculogenesis in cancer as well as other diseases, in which de novo vasculogenesis plays a crucial role. For instance, the list includes Syk and galectin-3, which encode protein tyrosine kinase and beta-galactoside-binding protein, respectively, and are expressed higher in EPCs than the three control endothelial cells. In situ hybridization showed that the genes were expressed in isolated cells in the fetal liver at E11.5 and E14.5 of mouse development.

Animals↗
PubMed2007

Lymphatic drainage of the peritoneal space: a pattern dependent on bowel lymphatics.

BACKGROUND: Understanding lymph drainage patterns of the peritoneum could assist in staging and treatment of gastrointestinal and ovarian malignancies. Sentinel lymph nodes (SLNs) have been identified for solid organs and the pleural space. Our purpose was to determine whether the peritoneal space has a predictable lymph node drainage pattern. METHODS: Rats received intraperitoneal injections of near-infrared (NIR) fluorescent tracers: namely, quantum dots (designed for retention in SLNs) or human serum albumin conjugated with IRDye800 (HSA800; designed for lymphatic flow beyond the SLN). A custom imaging system detected NIR fluorescence at 10 and 20 minutes and 1, 4, and 24 hours after injection. To determine the contribution of viscera to peritoneal lymphatic flow, additional cohorts received bowel resection before NIR tracer injection. Associations with appropriate controls were assessed with the chi(2) test. RESULTS: Quantum dots drained to the celiac, superior mesenteric, and periportal lymph node groups. HSA800 drained to these same groups at early time points but continued flowing to the mediastinal lymph nodes via the thoracic duct. After bowel resection, both tracers were found in the thoracic, not abdominal, lymph node groups. Additionally, HSA800 was no longer found in the thoracic duct but in the anterior chest wall and diaphragmatic lymphatics. CONCLUSIONS: The peritoneal space drains to the celiac, superior mesenteric, and periportal lymph node groups first. Lymph continues via the thoracic duct to the mediastinal lymph nodes. Bowel lymphatics are a key determinant of peritoneal lymph flow, because bowel resection shifts lymph flow directly to the intrathoracic lymph nodes via chest wall lymphatics.

Animals↗
PubMed2006

Transplantation of mesenchymal stem cells attenuates myocardial injury and dysfunction in a rat model of acute myocarditis.

Acute myocarditis is a non-ischemic inflammatory disease of the myocardium for which there is currently no specific treatment. We have previously shown that mesenchymal stem cells (MSC) can ameliorate heart injury during acute ischemia and in dilated cardiomyopathy; however, the therapeutic potential in acute myocarditis is unclear. In this study, we investigated the ability of MSC to attenuate myocardial injury and dysfunction during the acute phase of experimental myocarditis. Ten-week-old male Lewis rats were injected with porcine myosin to induce myocarditis. Cultured MSC (3x10(6) cells/rat) were injected intravenously 7 days after myosin injection. At 3 weeks, myosin injection resulted in severe inflammation and significant deterioration of cardiac function. MSC transplantation attenuated increases in CD68-positive inflammatory cells and monocyte chemoattractant protein-1 (MCP-1) expression in myocardium, and improved cardiac function in this model. Furthermore, myocardial capillary density was higher in myocarditis tissue, and was further increased by MSC transplantation. In vitro, cultured adult rat cardiomyocytes were injured in response to MCP-1, whereas this effect was attenuated by MSC-derived conditioned medium, suggesting cardioprotective effects of MSC acting in a paracrine manner. MSC transplantation attenuated myocardial injury and dysfunction in a rat model of acute myocarditis, at least in part through paracrine effects of MSC.

Acute Disease↗
PubMed2006

Beraprost sodium enhances neovascularization in ischemic myocardium by mobilizing bone marrow cells in rats.

Beraprost sodium, an orally active prostacyclin analogue, has vasoprotective effects such as vasodilation and antiplatelet activities. We investigated the therapeutic potential of beraprost for myocardial ischemia. Immediately after coronary ligation of Sprague-Dawley rats, beraprost (200 microg/kg/day) or saline was subcutaneously administered for 28 days. Four weeks after coronary ligation, administration of beraprost increased capillary density in ischemic myocardium, decreased infarct size, and improved cardiac function in rats with myocardial infarction. Beraprost markedly increased the number of CD34-positive cells and c-kit-positive cells in plasma. Also, four weeks after coronary ligation of chimeric rats with GFP-expressing bone marrow, bone marrow-derived cells were incorporated into the infarcted region and its border zone. Treatment with beraprost increased the number of GFP/von Willebrand factor-double-positive cells in the ischemic myocardium. These results suggest that beraprost has beneficial effects on ischemic myocardium partly by its ability to enhance neovascularization in ischemic myocardium by mobilizing bone marrow cells.

Animals↗
PubMed2006

Radiolabeled and near-infrared fluorescent fibrinogen derivatives create a system for the identification and repair of obscure gastrointestinal bleeding.

BACKGROUND: Gastrointesintal hemorrhage is often difficult to localize. A test that does not depend on active bleeding might prove clinically useful. We tested 2 novel fibrinogen (FBG)-based contrast agents for their ability to localize gastrointestinal (GI) hemorrhage after bleeding stopped. 125I-FBG permits gamma ray-based preoperative or intraoperative scanning, and near-infrared (NIR) flourescent FBG (FBG800) permits real-time intraoperative visualization of active clot. METHODS: Bovine FBG was radiolabeled with 125I or conjugated to the NIR fluorophore CW800. Sites of bleeding were created by gastrotomy, mucosal resection of the stomach, or laceration of a mesenteric vessel; then 1.7 mg/kg FBG800 or 15 microCi/kg 125I-FBG was injected intravenously into mice, rabbits, or pigs 30 minutes before or after injury. Sites of active clot were quantified by using gamma counting and were also imaged by using invisible NIR light intraoperatively, for up to 3 hours postinjection. RESULTS: After an injection of either 125I-FBG or FBG800, sites of prior bleeding could be identified in the absence of active bleeding. Blood clearance was such that a signal-to-background ratio of 2.0 or greater could be achieved within 20 minutes after injection. A similarly labeled human serum albumin did not accumulate at any site, with an SBR of 1.0 or less. CONCLUSIONS: Both radiolabeled (preoperative gamma scanning) and NIR fluorescent (intraoperative real-time imaging) FBG can be used in experimental situations to identify the location of prior bleeding in the absence of active bleeding. Taken together, these contrast agents create a system for the identification and control of obscure GI bleeding.

Animals↗
PubMed2006

Overexpression of the oncoprotein prothymosin alpha triggers a p53 response that involves p53 acetylation.

Activation of the tumor suppressor protein p53 is a critical cellular response to various stress stimuli and to inappropriate activity of growth-promoting proteins, such as Myc, Ras, E2F, and beta-catenin. Protein stability and transcriptional activity of p53 are modulated by protein-protein interactions and post-translational modifications, including acetylation. Here, we show that inappropriate activity of prothymosin alpha (PTMA), an oncoprotein overexpressed in human cancers, triggers a p53 response. Overexpression of PTMA enhanced p53 transcriptional activity in reporter gene assays for p53 target gene promoters hdm2, p21, and cyclin G. Overexpressed PTMA resulted in increased mRNA and protein levels for endogenous p53 target genes, hdm2 and p21, and in growth suppression. In contrast, reduction of endogenous PTMA through RNA interference decreased p53 transcriptional activity. Histone acetyltransferases (HATs) act as p53 coactivators and acetylate p53. PTMA, known to interact with HATs, led to increased levels of acetylated p53. PTMA did not increase the transcriptional activity of an acetylation-deficient p53 mutant, suggesting that p53 acetylation is an indispensable part of the p53 response to PTMA. Chromatin immunoprecipitation assays showed that excess PTMA associates with the p21 promoter and results in increased levels of acetylated p53 at the p21 promoter. Our findings indicate that overexpressed PTMA elicits a p53 response that involves p53 acetylation.

Acetylation↗
PubMed2006

Size series of small indium arsenide-zinc selenide core-shell nanocrystals and their application to in vivo imaging.

We have developed a size series of unusually small, water-soluble (InAs)ZnSe (core)shell quantum dots (QDs) that emit in the near-infrared and exhibit new behavior in vivo, including multiple sequential lymph node mapping and extravasation from the vasculature. The biological utility of these fluorescent probes resulted from our intentional choice to match the semiconductor material and water-soluble ligand with a desired final hydrodynamic diameter and emission wavelength.

Animals↗
PubMed2006

Novel expansion/shrinkage modulation of 2D layered MOF triggered by clathrate formation with CO(2) molecules.

Crystal-to-crystal transformation from a 3D interpenetrated-type MOF {[Cu(BF(4))(2)(bpy)(H(2)O)(2)] (bpy)} (1) to a 2D square-grid-type [Cu(BF(4))(2)(bpy)(2)] (2) (bpy = 4,4'-bipyridine) was observed. It was derived from dehydration and confirmed by in situ FT-IR, TG, and elemental analysis. Moreover, we elucidate the novel expansion/shrinkage dynamic modulation of 2 triggered by clathrate formation with gas molecules.

Adsorption↗
PubMed2006

[Ghrelin].

Explore the source record for details and available documents.

Animals↗
PubMed2005

Engineering InAs(x)P(1-x)/InP/ZnSe III-V alloyed core/shell quantum dots for the near-infrared.

Quantum dots with a core/shell/shell structure consisting of an alloyed core of InAs(x)P(1-x), an intermediate shell of InP, and an outer shell of ZnSe were developed. The InAs(x)P(1-x) alloyed core has a graded internal composition with increasing arsenic content from the center to the edge of the dots. This compositional gradient results from two apparent effects: (1) the faster reaction kinetics of the phosphorus precursor compared to the arsenic precursor, and (2) a post-growth arsenic-phosphorus exchange reaction that increases the arsenic content. The cores have a zinc blend structure for all compositions and show tunable emission in the near-infrared (NIR) region. A first shell of InP leads to a red-shift and an increase in quantum yield. The final shell of ZnSe serves to stabilize the dots for applications in aqueous environments, including NIR biomedical fluorescence imaging. These NIR-emitting core/shell/shell InAs(x)P(1-x)/InP/ZnSe were successfully used in a sentinel lymph node mapping experiment.

Alloys↗
PubMed2005

Intraoperative identification of esophageal sentinel lymph nodes with near-infrared fluorescence imaging.

OBJECTIVE: In esophageal cancer, selective removal of involved lymph nodes could improve survival and limit complications from extended lymphadenectomy. Mapping with vital blue dyes or technetium Tc-99m often fails to identify intrathoracic sentinel lymph nodes. Our purpose was to develop an intraoperative method for identifying sentinel lymph nodes of the esophagus with high-sensitivity near-infrared fluorescence imaging. METHODS: Six Yorkshire pigs underwent thoracotomy and received submucosal, esophageal injection of quantum dots, a novel near-infrared fluorescent lymph tracer designed for retention in sentinel lymph nodes. Six additional pigs underwent thoracotomy and received submucosal esophageal injection of CW800 conjugated to human serum albumin, another novel lymph tracer designed for uptake into distant lymph nodes. Finally, 6 pigs received submucosal injection of the fluorophore-conjugated albumin with an endoscopic needle through an esophagascope. These lymph tracers fluoresce in the near-infrared, permitting visualization of migration to sentinel lymph nodes with a custom intraoperative imaging system. RESULTS: Injection of the near-infrared fluorescent lymph tracers into the esophagus revealed communicating lymph nodes within 5 minutes of injection. In all 6 pigs that received quantum dot injection, only a single sentinel lymph node was identified. Among pigs that received fluorophore-conjugated albumin injection, in 5 of 12 a single sentinel lymph node was revealed, but in 7 of 12 two sentinel lymph nodes were identified. There was no dominant pattern in the appearance of the sentinel lymph nodes either cranial or caudal to the injection site. CONCLUSION: Near-infrared fluorescence imaging of sentinel lymph nodes is a novel and reliable intraoperative technique with the power to assist with identification and resection of esophageal sentinel lymph nodes.

Animals↗
PubMed2004

In vivo optical imaging of pleural space drainage to lymph nodes of prognostic significance.

BACKGROUND: Understanding the spatial and temporal drainage patterns of the pleural space could have profound impact on the treatment of lung cancer and mesothelioma. The purpose of this study was to identify the in vivo pattern of drainage from the pleural space to prognostic lymph node stations. METHODS: Fifty-six rats underwent pleural space injection of a novel lymph tracer composed of recombinant human serum albumin (HSA) covalently conjugated to the near-infrared (NIR) fluorophore IRDye78 via an amide bond (HSA-78). Nodal uptake was imaged at 10, 20, 30, and 60 minutes and 4, 12, and 24 hours after injection with a custom system that simultaneously acquires color video, NIR fluorescence of HSA-78, and a merged picture of the two. Six pigs underwent the same procedure with imaging at 30 minutes, 1 hour, and 24 hours. RESULTS: In both the rat model and the pig model, HSA-78 drained from the pleural space to superior mediastinal lymph nodes first, followed by other intrathoracic and then extrathoracic lymph nodes over the course of 24 hours. CONCLUSION: NIR fluorescence imaging in two species shows that the superior mediastinal lymph nodes are the first to drain the pleural space. Over the course of 24 hours, the pleural space also communicates with other intrathoracic and then extrathoracic lymph nodes. This study also demonstrates an intraoperative method for identifying nodes communicating with the pleural space, with potential utility in the staging and/or resection of lung cancer and mesothelioma.

Animals↗
PubMed2003

Downregulation and growth inhibitory effect of epithelial-type Krüppel-like transcription factor KLF4, but not KLF5, in bladder cancer.

Krüppel-like factors (KLFs) are key transcriptional regulators of cell differentiation and proliferation. Among the KLF family, the expression of KLF4 (GKLF) and KLF5 (IKLF) is highly restricted in the epithelial cells of several organs such as the gut and skin, and it has been reported that these epithelial-type KLF genes may be involved in colon carcinogenesis. Recently we found that Klf4 and Klf5 genes were significantly expressed in the developmental bladder epithelium of mice as well. Therefore, in this report we studied the involvement of the KLF4 and KLF5 genes in bladder carcinogenesis. First, we analyzed the expression of KLF4 and KLF5 in a variety of human bladder cancer cell lines and surgical specimens by RNA blot and in situ hybridization analyses. Both genes were highly expressed in the normal bladder epithelium, whereas KLF4, but not KLF5, was frequently downregulated in bladder cancer cell lines and cancer tissues. We then transduced the KLF4 and KLF5 genes into the bladder cancer cell lines using adenoviral vectors to examine the biological activities of the genes on those cells. The transduction of KLF4, but not KLF5, suppressed cell growth and induced apoptosis. Our study suggests that inactivation of KLF4 is one of the frequent steps towards bladder carcinogenesis.

Adenoviridae↗
PubMedDate not supplied

Tissue-like phantoms for near-infrared fluorescence imaging system assessment and the training of surgeons.

We demonstrate how to construct calibrated, stable, and inexpensive tissue-like phantoms for near-IR (NIR) fluorescence imaging applications. The bulk phantom material is composed of gelatin, intralipid, hemoglobin, and indocyanine green (ICG). Absorbance, scatter, background fluorescence, and texture can be tuned as desired. NIR fluorescent inclusions are comprised of ICG-labeled polystyrene divinylbenzene beads and Pam78-labeled hydroxyapatite crystals. The former mimic tumor masses of controllable size and contrast agent concentration, and the latter mimic microcalcifications in breast cancer. NIR-fluorescent inclusions can be positioned precisely in phantoms, with one or more regions having different optical properties, and their position can be verified independently using microcomputed tomography. We demonstrate how these phantoms can be used to calibrate and compare imaging systems, and to train surgeons to operate under NIR fluorescence image guidance.

Animals↗
PubMedDate not supplied

Organic alternatives to quantum dots for intraoperative near-infrared fluorescent sentinel lymph node mapping.

Intraoperative near-infrared (NIR) fluorescence imaging provides the surgeon with real-time image guidance during cancer and other surgeries. We have previously reported the use of NIR fluorescent quantum dots (QDs) for sentinel lymph node (SLN) mapping. However, because of concerns over potential toxicity, organic alternatives to QDs will be required for initial clinical studies. We describe a family of 800 nm organic heptamethine indocyanine-based contrast agents for SLN mapping spanning a spectrum from 775 Da small molecules to 7 MDa nanocolloids. We provide a detailed characterization of the optical and physical properties of these contrast agents and discuss the advantages and disadvantages of each. We present robust methods for the covalent conjugation, purification, and characterization of proteins with tetra-sulfonated heptamethine indocyanines, including mass spectroscopic site mapping of highly substituted molecules. One contrast agent, NIR fluorescent human serum albumin (HSA800), emerged as the molecule with the best overall performance with respect to entry to lymphatics, flow to the SLN, retention in the SLN, fluorescence yield and reproducibility. This preclinical study, performed on large animals approaching the size of humans, should serve as a foundation for future clinical studies.

Chromatography, Gel↗
PubMedDate not supplied

Diffuse neonatal hemangiomatosis without cutaneous lesions in an adult--a case report.

Diffuse neonatal hemangiomatosis (DNH) is a rare disorder that first presents with multiple cutaneous and visceral hemangiomas during the neonatal period and has a high mortality rate. The authors report a long-term survivor of DNH who presented with multiple visceral hemangiomas without cutaneous lesions. Vascular endothelial growth factor (VEGF) may play an important role in tumor progression.

Abdominal Neoplasms↗