Biomedical subjects

T Toyota

Publications and source records attributed to T Toyota.

At least 19 recordsLinked to original sources

PubMed2000

Changes in gastric acid secretion assayed by endoscopic gastrin test before and after Helicobacter pylori eradication.

BACKGROUND: It remains controversial whether or not Helicobacter pylori infection causes altered gastric acid secretion. A novel test for evaluating gastric acid secretion (endoscopic gastrin test; EGT) has recently been developed. AIM: To investigate by EGT the effects of H pylori eradication on the state of gastric acid secretion in patients with peptic ulcer. METHODS: Twenty six patients with duodenal ulcer and 33 with gastric ulcer, for all of whom H pylori infection had been documented, were studied by EGT, histological examination of gastric mucosa, and measurement of plasma gastrin levels before and one and seven months after H pylori eradication. RESULTS: In patients with duodenal ulcer, the mean EGT value before H pylori eradication was higher than that in H pylori negative controls, but it had decreased significantly seven months after the treatment. In contrast, the mean EGT value of patients with gastric ulcer before H pylori eradication was lower than that in H pylori negative controls, but it had increased one month after the treatment; this was followed by a slight decrease at seven months. In both groups, mean EGT values seven months after the treatment were not significantly different from the mean control value. CONCLUSIONS: The reduced acid secretion in gastric ulcer patients and gastric acid hypersecretion in duodenal ulcer patients were both normalised after the clearance of H pylori.

Adult↗

PubMed1999

The T3(b) gene promoter directs intestinal epithelial cell-specific expression in transgenic mice.

Although a few promoters that direct intestinal epithelial cell-specific expression in transgenic animals have been reported, they are not necessarily appropriate for transgenic studies in terms of activity and tissue specificity. Here, we examined the tissue specificity of transgene expression directed by the 2.8-kb promoter region of the T3(b) gene, which encodes one of the non-classical major histocompatibility complex class I molecules. The transgene was expressed exclusively in the epithelial cells of the small and large intestines at high levels. The results indicate that the T3(b) promoter is useful for directing transgene expression specifically in intestinal epithelial cells.

Animals↗

PubMed1999

Telomere shortening and the clinicopathologic characteristics of human colorectal carcinomas.

BACKGROUND: It has been reported that shortening of telomeres and strong activation of telomerase occur frequently in colorectal carcinomas. In the current study, the authors examined the correlations between the telomere length of colorectal carcinomas and their clinicopathologic characteristics as well as the activity of telomerase to clarify whether telomere length might represent the biologic behavior of tumors and the mode of tumor development. METHODS: Telomere length was examined by Southern blot analysis in 61 invasive colorectal carcinomas and corresponding normal mucosas. Telomerase activity was assayed by the telomeric repeat amplification protocol with minor modifications. RESULTS: Shortening of the telomere was detected in 38 (62.3%) and elongation in 3 (4. 9%) of the 61 carcinomas. The telomere shortening occurred more frequently in nonulcerating polypoid carcinomas than in ulcerating carcinomas (P = 0.0373) and also occurred more frequently in ascending colon carcinomas than in sigmoid colon or rectal carcinomas (P = 0.0259 and P = 0.0407, respectively). However, no significant correlation was found between the activity of telomerase and the length of telomere. CONCLUSIONS: The results of this study indicate that telomere length may represent the biologic behavior of individual tumors and possibly the mode of development of colorectal carcinomas.

Aged↗

PubMed1999

Oxidative DNA damage in diabetes mellitus: its association with diabetic complications.

AIMS/HYPOTHESIS: Augmented oxidative stress induced by hyperglycaemia possibly contributes to the pathogenesis of diabetic complications. Oxidative stress is known to increase the conversion of deoxyguanosine to 8-oxo, 2'-deoxyguanosine in DNA. To investigate the possible contribution of oxidative DNA damage to the pathogenesis of diabetic complications, we measured the content of 8-oxo, 2'-deoxyguanosine in the urine and the blood mononuclear cells of Type II (non-insulin-dependent) diabetic patients. METHODS: We studied 53 Type II diabetic patients and 39 age-matched healthy control subjects. We assayed 8-oxo, 2'-deoxyguanosine by HPLC-electrochemical detection method. RESULTS: The content of 8-oxo, 2'-deoxyguanosine in the urine and the mononuclear cells of the Type II diabetic patients was much higher than that of the control subjects. Urinary 8-oxo, 2'-deoxyguanosine excretion and the 8-oxo, 2'-deoxyguanosine content in the mononuclear cells from the diabetic patients with complications were higher than those from the diabetic patients without complications. Urinary excretion of 8-oxo, 2'-deoxyguanosine was significantly correlated with the 8-oxo, 2'-deoxyguanosine content in the mononuclear cells. The 8-oxo, 2'-deoxyguanosine content in the urine and mononuclear cells was correlated with the haemoglobin A1c value. CONCLUSIONS/INTERPRETATION: This is the first report of a direct association between oxidative DNA damage and the complications of diabetes. The augmented oxidative DNA damage in diabetes is speculated to contribute to the pathogenesis of diabetic complications.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Epalrestat prevents the decrease in gastric mucosal blood flow and protects the gastric mucosa in streptozotocin diabetic rats.

We have recently reported that steady-state gastric mucosal blood flow (GMBF) is decreased in streptozotocin (STZ) diabetic rats, and that their GMBF response to burn-stress is impaired, probably via a nitric oxide (NO)-mediated mechanism. Accordingly, this study was designed to investigate the relation of aldose reductase (AR) and NO synthase to the regulation of GMBF during chronic hyperglycemia. STZ rats were treated with or without chronic oral administration of an AR inhibitor, epalrestat (EPA) and/or an NO synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME). GMBF was measured by laser-Doppler velocimetry (LDV). In the STZ rats, GMBF after a 24-h fasting period was decreased significantly 4 weeks after the onset of diabetes and this was accompanied by an increase in the gastric ulcer index (UI) (a measure of the length of gastric erosions and ulcers). Chronic oral administration of EPA to the STZ rats dose-dependently inhibited the increased UI and the decreased GMBF after the fasting stress, whereas chronic oral administration of L-NAME further increased the UI and further decreased the GMBF. EPA administered in combination with L-NAME to the STZ rats reduced the effects of L-NAME, but the effects did not reach significance. These results suggest that EPA protects the gastric mucosa of diabetic rats, by preventing the decrease in GMBF that is, at least in part, caused by NO-related mechanisms.

Aldehyde Reductase↗

PubMed1999

Crohn's disease is associated with novel polymorphisms in the 5'-flanking region of the tumor necrosis factor gene.

BACKGROUND & AIMS: Tumor necrosis factor (TNF) is considered to play an important role in the pathogenesis of Crohn's disease (CD). Recently, 3 polymorphisms in the 5'-flanking region of the TNF gene at positions -1031, -863, and -857, which are related to high transcriptional promoter activity, have been identified in the Japanese population. In an effort to understand potential genetic association with CD, we evaluated patients diagnosed with CD and ulcerative colitis (UC) in the presence of other novel polymorphisms. METHODS: Blood samples were obtained from 103 patients with CD and 76 patients with UC. Polymorphisms in the TNF gene at their respective positions were analyzed by direct sequencing, and the allele frequencies were compared with those determined previously in a healthy Japanese population. RESULTS: Allele frequencies of -1031C, -863A, and -857T in normal controls were 16.0%, 14.0%, and 17.7%, respectively. Polymorphic allele frequencies at positions -1031, -863, and -857 were 24.3%, 21.8%, and 27.2% in CD and 11.8%, 11.2%, and 11.8% in UC, respectively. The frequencies at all 3 positions were significantly higher in CD patients than in UC patients or healthy controls. Among the subgroups of CD, small bowel disease showed the highest frequencies. CONCLUSIONS: Although the findings need to be confirmed in other populations with larger numbers of patients, TNF gene polymorphisms -1031C, -863A, and -857T are positively associated with CD; they may influence not only the susceptibility to CD but also the disease location.

Adult↗

PubMed1999

Helicobacter pylori-dependent ceramide production may mediate increased interleukin 8 expression in human gastric cancer cell lines.

BACKGROUND & AIMS: Helicobacter pylori adheres to gastric epithelial cells, activates nuclear factor kappaB (NF-kappaB), and stimulates interleukin (IL)-8 production, but the responsible molecular mechanisms remain largely unknown. Because several studies have shown that sphingolipids are involved in a number of signaling pathways, including NF-kappaB activation, we investigated the possible role of sphingolipids in the regulation of IL-8 expression in Kato III and AGS cells. METHODS: IL-8 production in the conditioned media was quantified by enzyme immunoassay. Induction of messenger RNA (mRNA) was assessed by Northern blot analysis. Activation and binding activity of transcription factors were examined by luciferase assay and electrophoretic mobility shift assay, respectively. Intracellular levels of ceramide were quantified by diacylglycerol kinase assay. RESULTS: A cell-permeable ceramide analogue (C2-ceramide) increased IL-8 expression with comparable mRNA induction. This effect was mimicked by sphingomyelinase, but not by phospholipase A2 or phospholipase C. C2-ceramide induced IL-8 gene transcription mainly through activation of NF-kappaB because mutation of the NF-kappaB-binding site completely abrogated the induction of luciferase activity. Direct contact of live H. pylori with epithelial cells increased the intracellular concentration of ceramide. CONCLUSIONS: The results suggest a novel role of the sphingomyelin-ceramide pathway, at least in part through NF-kappaB, in IL-8 production induced by H. pylori infection in gastric epithelial cells.

Ceramides↗

PubMed1999

Inhibition of tumor necrosis factor-alpha with anti-diabetic agents.

It has recently been indicated that tumor necrosis factor-alpha (TNF-alpha) production is increased under chronic hyperglycemia and TNF-alpha has harmful effects on insulin sensitivity and possibly on chronic diabetic complications. Therefore it will be favorable for diabetes treatment if anti-diabetic agents also have anti-TNF-alpha activities. In this study, we have investigated effects of hypoglycemic sulfonylureas (gliclazide and glibenclamide) and a thiazolidinedione (troglitazone) on lipopolysaccharide-induced TNF-alpha production, which was evaluated by immunoassay and bioassay, in vivo using mice and partly in vitro using human peripheral blood mononuclear cells. Gliclazide significantly inhibited TNF-alpha production in vivo and also in vitro at a concentration of 10(-3) mol/l. However, glibenclamide had neither effect on TNF-alpha production nor action. On the other hand, troglitazone inhibited action rather than production of TNF-alpha in vivo. In vitro troglitazone (10(-4) mol/l) significantly reduced cytolytic activity of TNF-alpha against LM cells. These results indicate that gliclazide and troglitazone have inhibitory effect on TNF-alpha.

Animals↗

PubMed1999

Microalbuminuria is closely related to diabetic macroangiopathy.

To investigate whether urinary excretion of transferrin (uTf) and albumin (uAlb) is related to diabetic macroangiopathy, we compared the levels of uTf and uAlb between ischemic heart disease (IHD) group and non-IHD group in patients with non-insulin-dependent diabetes mellitus. The patients (n = 102) without macroproteinuria were enrolled in the present study. Firstly, we divided the subjects into the two groups, IHD group (n = 16) and non-IHD group (n = 86), according to findings of ischemic changes on electrocardiogram. The levels of uTf and uAlb in IHD group were 3.9 +/- 0.9 and 40.6 +/- 9.7 (mean +/- S.E.M.) mg/g Creatinine, respectively. These values were significantly (P < 0.01) higher than those of non-IHD group (1.8 +/- 0.2 for uTf and 19.6 +/- 1.8 for uAlb). There was no significance in the levels of HbA1c, blood pressure, plasma lipids, and diabetic duration between the two groups. Secondly, we divided the subjects by the levels of uTf and uAlb. The frequency of IHD in the group (n = 22, 36.4%) with microalbuminuria and microtransferrinuria was significantly (P <0.03) higher than those (n = 38, 10.5%) with normoalbuninuria and microtransferrinuria, and also significantly (P < 0.02) higher than those (n = 42, 9.5%) with normoalbuminuria and normotransferrinuria. We concluded that the measurement of uAlb is important when approaching diabetic macroangiopathy.

Aged↗

PubMed1999

Oxidative damage to mitochondrial DNA and its relationship to diabetic complications.

Increased oxidative stress induced by hyperglycemia may contribute to the pathogenesis of diabetic complications. Oxidative stress is known to increase the conversion of deoxyguanosine (dG) to 8-hydroxydeoxyguanosine (8-OHdG) in DNA, which is linked to increased mitochondrial DNA (mtDNA) deletions. We investigated mtDNA deletions and 8-OHdG in the muscle DNA of non-insulin-dependent diabetes mellitus (NIDDM) patients. mtDNA deletion of 4977 bp (delta mtDNA4977) and the content of 8-OHdG in the muscle DNA of the NIDDM patients were much higher than those of the control subjects. There was a significant correlation between delta mtDNA4977 and the 8-OHdG content (P < 0.0001). Both delta mtDNA4977 and the 8-OHdG content were also correlated with the duration of diabetes. Delta mtDNA4977 and the 8-OHdG content in muscle DNA increased in proportion to the severity of diabetic nephropathy and retinopathy. This is the first report that an increase in delta mtDNA4977 and 8-OHdG is proportional to the severity of diabetic complications. Oxidative mtDNA damage is speculated to contribute to the pathogenesis of diabetic complications though a defect in mitochondrial oxidative phosphorylation or other mechanisms. 8-OHdG and delta mtDNA4977 are useful markers to evaluate oxidative mtDNA damage in the diabetic patients.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1999

Specific induction of adhesion molecules in human vascular endothelial cells by rat experimental pancreatitis-associated ascitic fluids.

The molecular mechanisms that link acute pancreatitis (AP) and multiple organ failure remain unknown. To clarify the role of endothelial activation, we examined the effects of ascitic fluids from rats with experimental pancreatitis on the expression of adhesion molecules in human umbilical vein endothelial cells (HUVECs). Necrotizing hemorrhagic pancreatitis was induced with sodium taurocholate. Six and 24 h later, peritoneal exudates were collected, centrifuged and HUVECs were treated with the supernatants. The expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was quantified by enzyme-linked immunosorbent assay. Induction of mRNA was assessed by reverse-transcriptase polymerase chain reaction. The activation of transcription factors was examined by electrophoretic mobility shift assay. The expression of ICAM-1 in the tissues was examined immunohistochemically. ICAM-1 and VCAM-1, but not E-selectin expression was upregulated with comparable mRNA induction. Nuclear factor kappaB was activated, while activator protein-1 binding activity was not altered. Immunohistochemically, enhanced ICAM-1 expression was observed in the pancreas and lung, but not in the liver. Ascitic fluids may contain soluble factors responsible for the transcriptional activation of endothelial adhesion molecules, and ICAM-1 may play roles in the pathogenesis of complicated AP.

Animals↗

PubMed1999

Changing distribution of islets in the developing human pancreas: a computer-assisted three-dimensional reconstruction study.

Tissue specimens of nine normal human pancreata from fetuses, neonates, and adults were subjected to serial sectioning and computer-assisted three-dimensional (3-D) reconstruction in an effort to study the growth of Langerhans' islets based on their distribution in the lobule and their relationship with the ducts and arterioles. Also, islet volumes were obtained by 3-D morphometry. In 24-week-old fetuses, the islets were shown to be in direct contact with the ducts, whereas in the neonates, they gradually became separated from the ducts, finally dispersing throughout the lobule in the adults. This transition seemed to allow islet hormones to have physiological effects on the exocrine function of the acinar tissue, making the pancreas achieve the endocrine-exocrine correlation. However, half of the islets remained next to the ducts even in the adult pancreata. With regard to the relationship between the islets and arterioles, "arteriolar" islets having an afferent arteriole accounted for approximately 20% in number, but their volume cumulated to approximately 70% of the total, comprising a greater part of the pancreatic endocrine gland.

Adult↗

PubMed1999

11C-methionine uptake to the pancreas and its secretion: a positron emission tomography study in humans.

The aim of this study was to investigate the uptake of [11C-methyl]-L-methionine (11C-methionine) in the human pancreas by analyzing dynamic positron emission tomography (PET) images and the duodenal aspirate. A double-lumen tube was inserted in the duodenum and dynamic PET was performed in seven healthy volunteers for 110 min after intravenous (i.v.) injection of 11C-methionine during the continuous i.v. administration of secretin (125 ng/kg/h) and cerulein (30 ng/kg/h). For the calculation of the radioactivity in the pancreas, the regions of interest were set on the PET images. Radioactivity was measured in 10-min fractions of duodenal juice. After i.v. injection, 11C-methionine accumulated in the pancreas within a few minutes, and the radioactivity plateaued during the study. The radiolabeled proteins in the duodenal juice increased linearly 30 min after 11C-methionine injection, but the relative rates of radioactivity in the protein precipitate to the total count in the duodenal juice were 44-48%. From these findings, it was concluded that 11C-methionine accumulation in the pancreas is very rapid after the i.v. administration, and only a part of methionine uptake to the pancreas is incorporated into secretory proteins. The pancreatic 11C-methionine uptake detected by PET may represent a new aspect of exocrine pancreatic function that has not been expressed by the conventional intubation method.

Adult↗

PubMed1999

Ascitic fluid of experimental severe acute pancreatitis modulates the function of peritoneal macrophages.

Although the pathophysiology of acute pancreatitis appears to be greatly influenced by the production of ascites, little is known about the mechanism. To investigate the effects of pancreatitis-associated ascitic fluid (PAAF) on macrophage function, we examined the effects of PAAF obtained from a rat model of severe acute pancreatitis on the ability of peritoneal macrophages to produce tumor necrosis factor-alpha (TNF-alpha). In addition, we compared the responses of PAAF-treated and PAAF-untreated macrophages to lipopolysaccharide (LPS) by evaluating their TNF-alpha production and nuclear factor-kappaB (NFkappaB) activation. Incubation of peritoneal macrophages with the PAAF led to the rapid and prolonged activation of NF-kappaB and to TNF-alpha production. Pyrrolidine dithiocarbamate, a potent inhibitor of NF-kappaB activation, attenuated the macrophage TNF-alpha production by PAAF. Macrophages produced TNF-alpha in response to LPS, but the cytokine production was significantly reduced when macrophages were pretreated with PAAF. The suppression of TNF-alpha production by PAAF pretreatment accompanied the impairment of NF-kappaB activation in response to LPS. These results indicate that the PAAF of severe acute pancreatitis may play important roles in the pathologic course of this disease through its effects on macrophage function.

Amylases↗

PubMed1999

Fas ligand is frequently expressed in human pancreatic duct cell carcinoma.

Fas ligand (Fas-L) is a key molecule in normal immune development, homeostasis, modulation, and function. Recent reports suggested that tumor cells can evade immune attack by killing lymphocytes through expressing Fas-L on the tumor cell surface. The expression of Fas-L has been demonstrated in pancreatic cancer cell lines and in tissues. The messenger RNA (mRNA) and protein expression of Fas-L was investigated in four pancreatic cancer cell lines and 19 human pancreatic duct cell carcinomas (PDCs) by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. In addition, coculture assay of Fas-L and Fas-expressing PANC-1 cells and Fas-sensitive Jurkat cells was performed. Fas-L mRNA expression was observed in all four cell lines as well as in 10 PDC tissues, and the protein expression was frequently detected in the PDC tissues (16 of 19 cases). The coculture experiments showed that PANC-1 cells induced apoptosis of Jurkat cells, whereas the PANC-1 cells themselves and Jurkat cells cultured without the presence of PANC-1 showed few apoptotic changes. These findings suggest that Fas-L may play an important role in the ability of PDCs to escape from immune surveillance through the induction of apoptosis in tumor-attacking lymphocytes. The frequent expression of Fas-L in PDCs may partly explain the notorious biologic behavior of PDCs.

Apoptosis↗

PubMed1999

Co-expression of Bcl-2 protein and vascular endothelial growth factor in hepatocellular carcinomas treated by chemoembolization.

AIMS/BACKGROUND: Transcatheter arterial chemoembolization (TAE) of hepatocellular carcinoma (HCC) causes anoxia. Escape of cancer cells from anoxic injury may be enhanced by induction of proteins which provide resistance to apoptosis. METHODS: We examined HCCs immunohistochemically for Bcl-2, vascular endothelial growth factor (VEGF), p53, and Ki67. The staining intensity for VEGF, a protein induced by anoxia, was assessed morphometrically with a computer-assisted image-analyzer. RESULTS: The frequency of Bcl-2 positive cells was higher in HCCs that had undergone TAE (TAE HCC) than that in HCCs that had not undergone TAE (41.75+/-15.06 vs. 1.01+/-0.79 cells/1000 cells, p = 0.0173). The frequency of p53- or Ki67-positive cells was not increased after TAE. Of 12 TAE HCCs, 7 had Bcl-2 positive HCC cells and 6 had clusters of Bcl-2 positive cells. In contrast, 2 of 11 HCCs that had not undergone TAE had only a few, sporadically distributed, Bcl-2-positive cells. The staining intensity for VEGF was higher in Bcl-2 positive than in Bcl-2 negative areas (1.208+/-0.091 vs. 1.071+/-0.017, p = 0.0222). Furthermore, the VEGF staining intensity in Bcl-2 positive areas of TAE HCCs was higher than in Bcl-2 negative areas (1.296+/-0.126 vs. 1.066+/-0.024, p = 0.0186), while in HCCs that had not undergone TAE the staining intensity was similar. CONCLUSIONS: TAE of HCC can induce Bcl-2 expression, possibly through anoxic stress.

Carcinoma, Hepatocellular↗

PubMed1999

Macrophages are essential for lymphocyte infiltration in formyl peptide-induced cholangitis in rat liver.

BACKGROUND/AIMS: Cholangitis in rats induced by N-formyl L-methionine L-leucine L-tyrosine (fMLT) is characterized by infiltration of mononuclear cells around bile ducts in portal tracts. METHODS: We investigated the initial process in fMLT-induced cholangitis histochemically. RESULTS: Administration of fMLT into the colons of adult male Wistar rats with acetate-induced colitis resulted in an infiltration of mostly macrophages and granulocytes into the portal tracts on day 1. Abnormal peroxidation as demonstrated by the nitro blue tetrazolium (NBT) reaction occurred in bile duct cells as well, although no apparent necrosis of the bile duct cells was observed. On day 4, the majority of the inflammatory cells in the portal tracts were CD4+ or CD8+ T lymphocytes. The oxidative products of the NBT reaction also disappeared from the bile duct cells. Administration of carrageenan, a potent inhibitor of macrophage function, resulted in a significant decrease in lymphocyte infiltration into the portal tracts. On day 8, portal inflammation subsided. CONCLUSIONS: In formyl peptide-induced cholangitis, macrophages and granulocytes may injure bile ducts transiently. Further, macrophages are necessary for the subsequent migration of T lymphocytes around the bile ducts.

Animals↗

PubMed1999

Helicobacter pylori infection inhibits reflux esophagitis by inducing atrophic gastritis.

OBJECTIVE: Although it is widely accepted that Helicobacter pylori (H. pylori) infection is an important cause of atrophic gastritis, few studies have examined the relationship between H. pylori-induced atrophic gastritis and the occurrence of reflux esophagitis. The present study was aimed to examine the relationship between H. pylori infection, atrophic gastritis, and reflux esophagitis in Japan. METHODS: A total of 175 patients with reflux esophagitis were compared with sex- and age-matched 175 control subjects. Diagnosis of H. pylori infection was made by gastric mucosal biopsy, rapid urease test, and serum IgG antibodies. Severity of atrophic gastritis was assessed by histology and serum pepsinogen I/II ratio. RESULTS: H. pylori infection was found in 59 (33.7%) patients with reflux esophagitis, whereas it was found in 126 (72.0%) control subjects. The grade of atrophic gastritis was significantly lower in the former than in the latter. Among the H. pylori-positive patients, atrophic gastritis was milder in the patients with reflux esophagitis than in the patients without it. CONCLUSIONS: These findings suggest that most cases of reflux esophagitis in Japan occur in the absence of H. pylori infection and atrophic gastritis, and it may also tend to occur in patients with milder gastritis even in the presence of H. pylori infection. Therefore, H. pylori infection may be an inhibitory factor of reflux esophagitis through inducing atrophic gastritis and concomitant hypoacidity.

Adult↗