PubMed Health⌕ Search

Biomedical subjects

Yuji Okada

Publications and source records attributed to Yuji Okada.

At least 37 records · Page 2Linked to original sources
PubMed2005

Expression of glial cell line-derived neurotrophic factor family members and their receptors in pancreatic cancers.

BACKGROUND: The glial cell line-derived neurotrophic factor (GDNF) is a member of neurotrophic polypeptide family, which promotes survival and rescue of various neural cells in the central and peripheral nerve systems. We previously reported that GDNF promotes tumor cell invasion in pancreatic cancer cell lines. The purpose of this study was to investigate GDNF family expression and the status of related receptors in actual cancer tissues, and assess correlations with clinicopathologic behavior. METHODS: Immunohistochemical assessment of GDNF, neurturin, persephin, artemin, GDNF family receptor alpha-1 and alpha-2, and RET was performed for 51 cases of surgically resected pancreatic cancer. RESULTS: In all intrapancreatic nerves, GDNF and artermin were expressed strongly. In pancreatic cancer tissues. The expression of RET was stronger than that seen in normal ductal cells and was significantly related to the survival rate after resection (P = .026) and lymphatic invasion (P = .014). Intrapancreatic neural invasion was significantly related to the expression of GDNF (P = .047). CONCLUSIONS: We conclude that the expression of RET in pancreatic cancer tissues may be a useful prognostic marker and GDNF may play an important role in neural invasion.

Adult↗
PubMed2005

Anaplastic carcinoma of the pancreas with squamous features: report of a case and immunohistochemical study.

BACKGROUND: Anaplastic carcinomas of the pancreas are rare aggressive tumors with survival measurable in weeks. Many terms have been applied used to describe these tumors, and anaplastic foci are identified in ductal adenocarcinomas and in ectopic pancreata, but are not the dominant pattern of growth. We herein present our experience with a case of anaplastic carcinoma of the pancreas with squamous features in order that allowed us to delineate the clinicopathologic and immunohistochemical features of this rare entity. CASE REPORT: According to imaging findings, the 77-year-old Japanese man was diagnosed as the malignant pancreatic tumor, and underwent a surgical resection. Histopathologically, anaplastic tumor cells showed focal ductal and squamous features infiltrated into pancreatic parenchyma, extrapancreatic fatty tissue, and stomach. The tumor cells showed strong reactivity for cytokeratin, alpha-SMA, vimentin, NSE, and S-100 protein. Although immunoreactivity against p53 was negative, strong positive immunostaining for proliferating cell nuclear antigen and interleukin-1 receptor type I (IL-1RI) was observed in a the majority of tumor cells, while the alpha6 integrin subunit was predominantly strong expressed in the adenocarcinomatous lesion. The patient's postoperative course was uneventful and he was treated with a chemotherapy consisting of gemcitabine. After discharging from the hospital, he had subsequently been observed as an outpatient and same chemotherapy was followed by weekly. However, the patient suffered from peritonitis carcinomatosa and re-increases of multiple liver metastases, and he died in the fourteenth month after surgery. CONCLUSIONS: Our immunohistochemical studies suggested that the prognosis of the case with anaplastic carcinoma presented here would be poor, due to the strong expression of integrins and IL-1RI.

Aged↗
PubMed2004

Metal-complexed nanofiber formation in water from dicarboxylic valylvaline bolaamphiphiles.

Nanofiber formation of dipeptide-based bolaamphiphiles, bis (N-alpha-amide--valyl--valine) 1,n-alkane dicarboxylate (n=6, 8, 10, and 12) in water was analyzed by TEM, SEM, IR, and XRD. The bolaamphiphiles proved to be coordinated to divalent transition-metal cations, such as Co2+, Ni2+, Cu2+, and Zn2+, giving precipitates, colloidal dispersions (loose hydrogels), and hydrogels upon self-assembly at 23 or 70 degrees C. Longer oligomethylene chains and strong interaction between the metal cations and the carboxylate anions are responsible for the hydrogel formation. Energy-filtering transmission electron microscopy (EF-TEM) and field-emission scanning electron microscopy (EF-SEM) images revealed that the colloidal dispersions and the hydrogels consist of a large number of nanofibers with widths of 15-20 nm and lengths of several micrometers. FT-IR and powder XRD measurement supported the existence of a beta-sheet structure-based nanofibers complexing with metal cations.

Journal Article↗
PubMed2004

Design and synthesis of Rho kinase inhibitors (I).

Several structurally unrelated scaffolds of the Rho kinase inhibitor were designed using pharmacophore information obtained from the results of a high-throughput screening and structural information from a homology model of Rho kinase. A docking simulation using the ligand-binding pocket of the Rho kinase model helped to comprehensively understand and to predict the structure-activity relationship of the inhibitors. This understanding was useful for developing new Rho kinase inhibitors of higher potency and selectivity. We identified several potent platforms for developing the Rho kinase inhibitors, namely, pyridine, 1H-indazole, isoquinoline, and phthalimide.

Amino Acid Sequence↗
PubMed2004

Temperature- and pH-responsive aminopropyl-silica ion-exchange columns grafted with copolymers of N-isopropylacrylamide.

We have designed copolymers of N-isopropylacrylamide, environmentally-responsive polymers, which respond to temperature and other external stimuli. In this study, we designed and synthesized copolymers that introduced ion-exchange groups. These copolymers responded to the temperature and the pH, and the copolymer-grafted aminopropyl silica beads were used as HPLC packing materials. This stationary phase altered the properties from hydrophilic to hydrophobic and from charge to non-charge by temperature and pH changes. We studied the separations of organic acids and phenylthiohydantoin-amino acids using environmentally-responsive chromatography, and confirmed the effects of the ion-exchange groups. The elution behaviors of these samples were controlled by the temperature changes without organic solvents in the mobile phase. It was confirmed that the interactions between the solute and stationary phase could be freely controlled by the temperature and the pH. Environmentally-responsive chromatography is expected to be applicable to the separation of pharmaceuticals and biomolecules, such as peptides, proteins and nucleic acids.

Acrylamides↗
PubMed2004

Nerve growth factor stimulates MMP-2 expression and activity and increases invasion by human pancreatic cancer cells.

Pancreatic cancer frequently invades and migrates along neural tissue. Although the exact mechanisms are unknown, perineural invasion negatively impacts prognosis for pancreatic cancer patients. Matrix metalloproteinases (MMPs) are overexpressed in pancreatic cancer and are associated with poor prognosis. We hypothesized that nerve growth factor (NGF) released from neural tissue increases the invasive properties of pancreatic cancer cells. In the present study we investigated the effect of NGF on the expression and activity of MMP-2 in human pancreatic cancer cells. NGF dose dependently increased MMP-2 protein in the culture medium and stimulated MMP-2 gelatinolytic activity. This effect was mediated by specific binding of NGF to its receptor trk A, which was detected on all pancreatic cancer cells, with subsequent activation of the p44/42 MAPK signaling pathway. The NGF-induced increase in MMP-2 expression and activity lead to an enhanced invasion in vitro. These findings support the hypothesis that neurotrophic factors, e.g., NGF, are critically involved in mediating perineural invasion of pancreatic cancer.

Cell Line, Tumor↗
PubMed2004

Expression of integrins in intraductal papillary-mucinous tumors of the pancreas as an indicator of malignancy.

INTRODUCTION AND AIMS: Intraductal papillary-mucinous tumors (IPMTs) of the pancreas are intraductal tumors with diffuse or segmental dilation of the pancreatic ducts and intraductal papillary growth with abundant mucous secretion. We examined clinicopathological features and immunohistochemical findings to investigate the malignancy of IPMTs. METHODOLOGY: Between April 1994 and December 2002, 23 patients with IPMT underwent pancreatic resections at Nagoya City University Hospital, Japan. We immunohistochemically analyzed the expression of p53 protein, proliferating cell nuclear antigen, alpha6-integrin subunit, alpha5beta1 integrin, and interleukin-1 receptor type I in tumor specimens from the 23 patients with IPMT. RESULTS: The tumors were classified as intraductal papillary adenoma (n = 16), intraductal papillary adenocarcinoma and moderate dysplasia (n = 7). At a median follow-up of 42.9 months, 2 patients had died of this disease. The actuarial 5-year disease-free survival rate was 80.7%. Expression of the alpha6-integrin subunit was significantly strong in adenocarcinoma and moderate dysplasia tissues of IPMTs (P = 0.038). CONCLUSIONS: Our current results indicate that alpha6-containing integrin expression can be a significant marker of malignancy in IPMTs. We emphasize that immunohistochemical investigation of resected specimens is indispensable in cases of IPMT, so that appropriate postoperative treatments for malignant IPMTs are initiated to improve prognosis.

Adenocarcinoma, Mucinous↗
PubMed2004

Enhanced angiogenesis due to inflammatory cytokines from pancreatic cancer cell lines and relation to metastatic potential.

OBJECTIVES: To investigate the mechanisms of metastasis formation in human pancreatic carcinoma, we examined the angiogenic capabilities of human pancreatic cancer cell lines with different metastatic potentials and the roles of inflammatory cytokines. METHODS: Interleukin (IL)-8 secretion by human pancreatic cancer cells stimulated with IL-1alpha or IL-1 receptor antagonist (IL-1ra) was measured by enzyme-linked immunosorbent assay (ELISA). We then examined how cancer cells with different metastatic potentials influenced the proliferation and tube formation of human umbilical vein endothelial cells (HUVECs) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye reduction method (MTT assay) and an angiogenesis assay, respectively. We also examined the role of inflammatory cytokines in relation to tumor metastatic potential and angiogenesis. RESULTS: IL-8 secretion levels by pancreatic cancer cells were regulated by IL-1alpha and correlated with metastatic potential. Both HUVEC proliferation and tube formation were strongly enhanced by coculture with metastatic pancreatic cancer cells and were enhanced to a similar extent by culture in the presence of IL-1alpha and IL-8. In contrast, blockade of IL-1alpha or IL-8 inhibited HUVEC proliferation and angiogenesis. CONCLUSIONS: The inflammatory cytokines IL-1alpha and IL-8 may have an important role in metastasis via vascular endothelial cell proliferation and angiogenesis.

Cell Division↗
PubMed2004

Glial cell line-derived neurotrophic factor enhances nuclear factor-kappaB activity and invasive potential in human pancreatic cancer cells.

OBJECTIVES: The invasive potential is increased by glial cell line-derived neurotrophic factor (GDNF) in human pancreatic cancer cell lines. We researched whether the signaling pathway activated by GDNF correlates with the nuclear factor-kappaB (NF-kappaB) in human pancreatic cancer cell lines and whether the inhibition of NF-kappaB activity is associated with suppression of invasive potential. METHODS: Proliferation of human pancreatic cancer cell lines (BxPC-3 and MIA PaCa-2) was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays (MTT assay). NF-kappaB activity was examined by dual luciferase assay and electrophoretic mobility shift assay. In addition, to investigate the invasive potential, an in vitro invasion assay was performed. RESULTS: Proliferation of both cell lines was decreased by a proteasome inhibitor, MG132, in a dose-dependent manner, but proliferation of control and IkappaBalphaM vector-transfected BxPC-3 cells was similar. The invasion cell number and the NF-kappaB activity were increased by GDNF stimulation. However, in the presence of MG132 or IkappaBalphaM, which blocks the nuclear localization of NF-kappaB, both were significantly suppressed. Furthermore, reduced activity of both remained unchanged by GDNF stimulation. CONCLUSION: These results indicate that GDNF promotes NF-kappaB activation and that the latter is involved in the invasive potential of human pancreatic cancer cells.

Cell Division↗
PubMed2004

Expression of integrins in tumour tissue of a patient with cancer of the Vater's ampulla complicated by pancreas divisum.

We present herein a rare case where cancer of the Vater's ampulla was complicated with pancreas divisum. Endoscopic retrograde cholangiopancreatography demonstrated the pancreas divisum and stenosis of the common channel due to the tumorous lesion of the Vater's ampulla. Magnetic resonance cholangiopancreatography demonstrated that the Wirsung duct and Santorini duct were unconnected. The biopsy specimen at the upper gastrointestinal endoscopy revealed moderately differentiated tubular adenocarcinoma. The patient was diagnosed with cancer of the Vater's ampulla complicated with pancreas divisum, and underwent a pylorus-preserving pancreaticoduodenectomy. Immunohistochemical examination showed that the p53 protein and the alpha5beta1-integrin were expressed in tumour cells, and the proliferating cell nuclear antigen test was positive. Furthermore, the alpha5beta1-integrin was expressed in chronic pancreatitis tissue. We demonstrate that there is a risk that pancreas divisum will co-exist with malignant disease in the pancreaticobiliary area, causing a potential risk of complicating malignant diseases in the pancreas.

Adenocarcinoma↗
PubMed2004

Effects of topically instilled bunazosin, an alpha1-adrenoceptor antagonist, on constrictions induced by phenylephrine and ET-1 in rabbit retinal arteries.

PURPOSE: To examine the inhibitory effects of topically instilled bunazosin hydrochloride (bunazosin), a selective alpha1-adrenoceptor antagonist, on the retinal artery constrictions induced by intravitreous phenylephrine hydrochloride (phenylephrine) and endothelin (ET)-1 in rabbits. METHODS: Phenylephrine or ET-1 (20 microL) was injected into the central part of the vitreous in both eyes in pigmented rabbits. Color fundus photographs were taken at 5 minutes before and 60 minutes after the injection. The average diameter of the major retinal arteries at the rim of the optic nerve head (ONH) was normalized with respect to ONH diameter. Bunazosin was instilled into one eye (chosen randomly) and vehicle into the fellow eye at 60 minutes before the intravitreous injection. To examine any interaction between the alpha1-adrenoceptor and ET receptor, phenylephrine and ET-1 were co-injected at individually ineffective doses. In addition, ET-1-induced vasoconstriction was examined after unilateral superior cervical ganglionectomy. The binding affinities of bunazosin for ETA and ETB receptors were also evaluated. The series of experiments was performed as masked tests. RESULTS: Retinal arteries were dose-dependently constricted by both intravitreous phenylephrine and intravitreous ET-1. Topically instilled bunazosin at 0.01% partly inhibited both of these vasoconstrictions on the ipsilateral side, but not on the contralateral side. Bunazosin did not bind to ET receptors. Co-injection of phenylephrine and ET-1 at individually ineffective doses constricted retinal arteries significantly. An adrenergic supersensitivity in retinal arteries was observed after superior cervical ganglionectomy only on the ganglionectomized eye. The ET-1-induced vasoconstriction was significantly weaker in cervical ganglionectomized eyes than in sham-surgery eyes. CONCLUSIONS: The present findings suggest that topically instilled bunazosin reaches the posterior retina by local penetration at concentrations sufficient to attenuate the phenylephrine- or ET-1-induced constriction of retinal arteries in normal rabbit eyes, and that the inhibitory effect of bunazosin on the ET-1-induced vasoconstriction in this tissue may be partly attributable to an interaction between the alpha1-adrenoceptor and ET receptor.

Administration, Topical↗
PubMed2004

[A case of pulmonary thromboembolism after cardiac surgery].

It has been reported that pulmonary thromboembolism (PTE) is a major complication in the post-operative period. However, there have been few reports on PTE after cardiopulmonary bypass (CPB). We report a case of PTE that occurred after cardiac surgery using CPB. A 76-year-old female patient underwent aorto-coronary graft bypass and mitral valve plasty because of ischemic heart disease and mitral valve regurgitation, respectively. The results of blood gas analysis after cardiopulmonary bypass showed no abnormalities. Immediately after ICU admission, the oxygenation index (PaO2/FIO2) of the patient was below 100, and the low level persisted despite decrease in interstitial fluid volume of the lung. Evaluations of hemodynamics using ultrasound echography and a Swan-Ganz catheter showed no findings associated with right heart failure. The results of lung perfusion scintigraphy performed on the 6th postoperative day (POD), revealed the decline in radioactivities in the upper and middle lobe areas of the right lung. Urokinase was therefore administered intravenously from the 6th to 9th POD. The oxygenation index increased dramatically after urokinase administration. Although the use of thrombolytic therapy in an early postoperative period is controversial, our patient was successfully treated with urokinase without a life-threatening bleeding tendency.

Aged↗
PubMed2004

[The QOL of the patient with advanced pancreatic carcinoma was changed for the better with combination therapy consisting of arterial chemotherapy and injection of interferon].

The prognosis of advanced pancreatic carcinoma with multiple liver metastases is extremely poor. The current methods of treating pancreatic carcinoma are far from satisfactory. The results of systemic and regional chemotherapies for pancreatic carcinoma are disappointing. The patient was a 68-year-old male with advanced pancreatic carcinoma. After an operation, he received a combination therapy consisting of arterial infusion (gemcitabine hydrochloride, GEM, 600 mg) and muscle injection of interferon (IFN, 300x10(4) U). A decrease in metastatic tumor of the liver was observed. In this report, we describe the case of a patient whose effective results were achieved by using a new combination of GEM and IFN.

Aged↗
PubMed2003

Thromboxane A2 regulates vascular tone via its inhibitory effect on the expression of inducible nitric oxide synthase.

BACKGROUND: Circulatory failure in sepsis arises from vascular hyporesponsiveness, in which nitric oxide (NO) derived from inducible NO synthase (iNOS) plays a major role. Details of the cross talk between thromboxane (TX) A2 and the iNOS-NO system, however, remain unknown. We intended to clarify the role of TXA2, via the cross talk, in vascular hyporesponsiveness. METHODS AND RESULTS: We examined cytokine-induced iNOS expression and NO production in cultured vascular smooth muscle cells (VSMCs) and cytokine-induced hyporesponsiveness of the aorta from mice lacking the TXA2 receptor (TP-/- mice). The cytokine-induced iNOS expression and NO production observed in wild-type VSMCs were significantly augmented in TP-/- VSMCs, indicating an inhibitory effect of endogenous TXA2 on iNOS expression. Furthermore, in indomethacin-treated wild-type VSMCs, U-46619, a TP agonist, inhibited cytokine-induced iNOS expression and NO production in a concentration-dependent manner, effects absent from TP-/- VSMCs. In an ex vivo system, the cytokine-induced hyporesponsiveness of aortas to phenylephrine was significantly augmented in TP-/- aorta but was almost completely canceled by aminoguanidine, an iNOS inhibitor. Accordingly, cytokine-induced NO production was significantly higher in TP-/- aorta than in wild-type aorta. Moreover, U-46619 significantly suppressed lipopolysaccharide-induced NO production in vivo only in wild-type mice. CONCLUSIONS: These results suggest that TXA2 has a protective role against the development of vascular hyporesponsiveness via its inhibitory action on the iNOS-NO system under pathological conditions such as sepsis.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2003

PGE(2) is generated by specific COX-2 activity and increases VEGF production in COX-2-expressing human pancreatic cancer cells.

In some cancers cyclooxygenase (COX) inhibition appears to be anti-mitogenic and anti-angiogenic, but the actions of COX-derived prostaglandins in pancreatic cancer (PaCa) are unknown. In this study COX-2 was detected in three of six PaCa cell lines while COX-1 was identified in all cell lines. COX-2 expression correlated with basal and arachidonic acid (AA) stimulated PGE(2) production. PGE(2) production was inhibited by the COX-2 inhibitor nimesulide. In COX-2 expressing cells, exogenous AA and PGE(2) increased VEGF synthesis via the EP(2) receptor. Whereas PGE(2) stimulated intracellular cAMP formation in COX-2 positive and negative cells, 8-bromo cAMP stimulated VEGF production only in COX-2 expressing cells. Stimulating COX-2 expressing PaCa cell lines with AA enhanced migration of endothelial cells, an effect which was inhibited by a COX-2 inhibitor and EP(2) receptor antagonist. These data identify a subset of human PaCa cell lines that express functional COX-2 enzyme. PGE(2) generated by specific COX-2 activity increases VEGF secretion in human PaCa cells through an autocrine mechanism.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2003

Enhancement of integrins by interleukin-1alpha, and their relationship with metastatic and invasive behavior of human pancreatic ductal adenocarcinoma cells.

BACKGROUND AND OBJECTIVES: Adhesion and invasion of tumor cells to extracellular matrix (ECM) proteins play an important role in tumor metastasis formation. We investigated the enhancement of adhesive and invasive behavior to ECM proteins of human pancreatic cancer cells by interleukin-1alpha (IL-1alpha) to examine the mechanism of adhesion and invasion of metastatic human pancreatic cancer cells to ECM proteins. METHODS: The enhancement of integrin subunits by IL-1alpha was examined by cellular enzyme-linked immunosorbent assay (CELISA) in two metastatic human pancreatic cancer cell lines (BxPC-3 and SW1990) and two nonmetastatic pancreatic cancer cell lines (PaCa-2 and PANC-1). In addition, assays of cancer cell adhesion and invasion to ECM proteins were performed to investigate whether increased integrin expression affected the invasive interaction between cancer cells and the putative integrin ECM ligands. RESULTS: Expression of the alpha6 subunit by metastatic cancer cells was enhanced by IL-1alpha. Metastatic cancer cells also exhibited preferential adherence and invasion to laminin compared with nonmetastatic cancer cells, and this was enhanced by IL-1alpha. CONCLUSIONS: The enhancement of alpha6beta1-integrin by Il-1alpha acting through IL-1RI, as well as the expression of alpha6beta1-integrin, plays an important role in metastasis formation in pancreatic cancer

Carcinoma, Ductal, Breast↗