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Biomedical subjects

K Kasugai

Publications and source records attributed to K Kasugai.

At least 19 recordsLinked to original sources
PubMed2006

Crucial role of c-Jun NH2-terminal kinase 1 (JNK1) in cold-restraint stress-induced gastric lesions in mice.

c-Jun NH2-terminal kinase 1 /JNK1, is activated in response to a broad array of cellular stresses. We investigated the role of JNK1 in the pathophysiology of cold-restraint stress-induced gastric lesions in mice. B6/129, wild type (WT) mice, or mutant mice deficient in Jnk1 (Jnk1-/- mice) were exposed to cold-restraint stress for different time periods. Gastric lesions were identified and quantitated by morphometric analysis. JNK1 activity in mucosal homogenates was quantitated by immunoprecipitation and in-vitro kinase assays. JNK1 expression and Akt activation were assessed by Western blots with anti-JNK1 and anti-phospho Akt antibodies, respectively. Gastric mucosal homogenates from Jnk1-/- mice exhibited no significant expression of JNK1 and no detectable level of JNK1 activation. Exposure of WT mice to cold-restraint stress led to the development of significant gastric lesions and to a greater than three-fold induction in JNK1 activity, while no lesions were detected in the gastric mucosa of Jnk1-/- mice. Since cold-restraint stress-induced gastric lesions involve the activation of cholinergic pathways, we tested the effect of atropine on both the development of gastric lesions and JNK1 activation. Pretreatment of WT mice with atropine completely inhibited both cold-restraint stress-induced lesions and JNK1 activation. Cold-restraint stress induced protein kinase B/Akt to a similar level in the gastric mucosa of both WT and Jnk1-/- mice indicating the integrity of other signaling pathways. JNK1 plays a key role in the development of cold-restraint stress-induced gastric lesions in mice through the activation of cholinergic, atropine sensitive pathways.

Animals↗
PubMed2001

Acid stimulates E-cadherin surface expression on gastric epithelial cells to stabilize barrier functions via influx of calcium.

BACKGROUND AND AIMS: E-cadherin, which is a [Ca2+]-dependent, homotypic cell-cell adhesion molecule, is expressed in gastrointestinal epithelial cells. Much has been learned about the down-regulation of E-cadherin expression in gastrointestinal tumours, Barrett's oesophageal dysplasia, and Crohn's disease, but the functions of this molecule in normal gastrointestinal mucosa are less known. METHODS: In this study, we investigated the relationship between E-cadherin expression and permeability using rat cultured gastric and intestinal epithelial cells following a 30-min exposure to various pH solutions. We also investigated the participation of [Ca2+] in these events. RESULTS: E-cadherin expression increased under acid (pH 4) but not alkali (pH 10 or 11) exposure only for gastric epithelial cells. Gastric epithelial permeability was maintained only against acid exposure while intestinal permeability increased under both conditions. Transient influx of [Ca2+] was only observed for gastric epithelial cells just after acid exposure. CONCLUSIONS: These findings suggest that E-cadherin expression on gastric epithelium stabilizes the epithelial barrier against acid, probably through influx of [Ca2+]. This event is thought to be one of the protective mechanisms in gastric mucosa against acid back-diffusion, which is one of the causes of peptic ulcer formation.

Acids↗
PubMed2000

What are the appropriate indications for endoscopic mucosal resection for early gastric cancer? Analysis of 256 endoscopically resected lesions.

BACKGROUND AND STUDY AIMS: Although endoscopic mucosal resection (EMR) for early gastric cancer (EGC) without ulceration or scarring has been very popular in Japan and thought to be beneficial, curability by EMR is still lower than that for surgical resection. We investigated patients whose EGCs were resected endoscopically in order to identify the factors affecting curability by EMR. PATIENTS AND METHODS: We investigated retrospectively 256 EGC lesions (251 patients) which were subjected to EMR between 1989 and 1998 with respect to patient profile, macroscopic type, location, maximum diameter of tumors, resection method and histological typing. The prognoses of the patients were also investigated as far as possible. RESULTS: The curative total resection rate for EMR of EGC was 74.2 %. Concerning the factors affecting curability, the size of the lesion (over 15 mm), the method of resection (divisional resection), and histological typing (poorly differentiated) had a statistically significant effect on the complete resection rate. Multivariate analysis of the factors confirmed these results. Submucosal invasion was suspected in 16 patients after EMR, but submucosal cancer was found in only one patient after further surgery. Where there was recurrence, the longest recurrence-free period after EMR of EGC was 48 months, whereas the mean recurrence-free period was 195.4 days. CONCLUSIONS: The appropriate indication for EMR for EGC is thought to be an intramucosal differentiated-type adenocarcinoma without ulceration or scarring, and no more than 15 mm in size regardless of macroscopic type. Periodic follow-up for at least 5 years is necessary.

Adenocarcinoma↗
PubMed2000

Midgut malrotation in adulthood.

A 29-year-old man was admitted to our hospital with a history of recurrent right upper quadrant abdominal pain and vomiting. These symptoms appeared intermittently for 7 years. Various examinations revealed a diagnosis of midgut malrotation. Laparotomy was performed and revealed reverse rotation of the duodenum with paraduodenal hernia and a normal rotating colon. This case suggests that recurrent abdominal complaints in an adult should arouse suspicion of midgut malrotation.

Abdominal Pain↗
PubMed1999

Primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma with polypoid appearance. Polypoid gastric MALT lymphoma: A clinicopathologic study of eight cases.

In the current study, we report eight cases with primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma endoscopically characterized by polypoid lesions in order to highlight their clinicopathologic significance. Four patients were male, their ages ranging from 40 to 78 years old. The resected specimens revealed a histology of low-grade MALT lymphoma characterized by dense lymphocytic infiltration predominantly in the submucosa and a relatively monotonous proliferation of centrocyte-like cells with reactive follicles and infrequent lymphoepithelial lesions. The tumor cells were of CD5-, CD10-, CD20+, BCL2+ and cycline D1- phenotype, and showed a monoclonal rearrangement of immunoglobulin heavy chain genes in the five of six cases examined. Interestingly, Helicobacter pylori (H. pylori) was detected in three (37.5%) of the eight patients, which was significantly lower than previous reports. Two of the H. pylori-positive cases initially underwent H. pylori eradication, but showed no change in their lymphomas after the cure of H. pylori infection. The clinicopathologic findings of the present cases appeared to closely resemble those of colorectal MALT lymphoma with a polypoid appearance and few association of H. pylori infection in their pathogenesis. These gastric polypoid cases may merit separate consideration because of the therapeutic problems they pose.

Adult↗
PubMed1999

Clinicopathological study on liver dysfunction in measles.

We analyzed the clinical course of eight patients with liver dysfunction in measles. All of the patients showed an elevation of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH), but no jaundice. These levels returned to normal about 3 weeks after the onset of the rash. A percutaneous liver biopsy was done in two cases. Histological examination showed slight necrosis of liver cells but no significant changes in portal area. On electron microscopy, virus particles were not detected. We detected measles virus RNA in the liver specimen by RT-PCR, which suggests that the measles virus affects liver cells directly in measles.

Adolescent↗
PubMed1998

Expression of mRNA for heregulin and its receptor, ErbB-3 and ErbB-4, in human upper gastrointestinal mucosa.

Expression of mRNA for heregulin (HRG), a member of the epidermal growth factor (EGF) family and its receptors, ErbB-3 and ErbB-4, were evaluated in human upper gastrointestinal (GI) mucosa. Multi-target reverse-transcriptase polymerase chain reaction (RT-PCR) analysis using capillary electrophoresis and laser-induced fluorescence allowed us to quantify the minute amounts of mRNA from one biopsy specimen with high sensitivity. HRG, ErbB-3 and ErbB-4 mRNA were detected in esophagus, stomach and duodenum and the highest expression was found in duodenum. In gastric cancer, mRNA for ErbB-4 was significantly overexpressed. Immunoreactivity of ErbB-4 in carcinoma cell membrane was also confirmed. These findings suggest that HRG and its receptors, ErbB-3 and ErbB-4 may be physiologically significant in the human upper GI mucosa, especially in duodenum, and that ErbB-4 may contribute to the growth of gastric cancer.

ErbB Receptors↗
PubMed1997

Evidence for participation of gliostatin/platelet-derived endothelial cell growth factor in gastric ulcer healing.

Gliostatin (GLS)/Platelet-derived endothelial cell growth factor (PD-ECGF) is a protein factor that has angiogenic and thymidine phosphorylase activity. It has been recently demonstrated to be related to disease activity in rheumatoid arthritis. However, its physiological role in the gastric mucosa is unknown. In the present study, concentrations of this protein in human gastric mucosa and plasma were evaluated. Further, the effect of purified human GLS/PD-ECGF on experimental ulcer healing was investigated in the rat. The human plasma concentration of GLS/PD-ECGF was significantly higher in patients with intractable gastric ulcer than in patients with significant resolution. The tissue content was significantly higher at the gastric ulcer edge than in either the fundic or pyloric region. GLS/PD-ECGF infusion delayed ulcer healing in a dose-dependent manner. These results suggest that gastric tissue and/or circulating GLS/PD-ECGF may participate in pathology and etiology of gastric ulcers and that this mechanism may relate to the pathogenesis of RA.

Animals↗
PubMed1997

Mitogenic properties of human gastric juice.

This study was performed to define the biologically active growth modulators in human gastric juice. Mitogenic activity was evaluated by the incorporation of [3H]thymidine into 3T3 fibroblasts. A negative correlation was observed between pH and mitogenic activity in gastric juice (r = -0.45, P < 0.01). The concentrations of epidermal growth factor (EGF), transforming growth factor-alpha and -beta 1 (TGF-alpha and -beta 1), platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF) in gastric juice did not explain these changes in mitogenic activity. Gel filtration identified growth-stimulating activity due to small molecule mitogens (less than 13 kDa), and growth inhibitory activity only in neutral samples due to a macromolecular substance (larger than 240 kDa) susceptible to trypsin digestion and heat and acid treatments. We conclude that acidity-dependent changes in mitogenic activity observed in this study are due to appearance of acid-unstable, high-molecular-weight, growth-inhibitory substance.

3T3 Cells↗
PubMed1996

Effects of the anti-gastric secretory drugs IT-066 and omeprazole mitogenic activities in the gastric juice of the rat.

BACKGROUND: Salivary epidermal growth factor (EGF) retains its biologic function in gastric juice and may play a physiologic role. Little is know, however, about the existence of mitogens other than EGF and the constitutional alterations of these factors in gastric juice by anti-secretagogues. METHODS: The mitogenic activity was evaluated by measuring [3H]-thymidine incorporation, and the EGF contribution was determined by using a specific anti-rat EGF antibody. An H2-receptor antagonist (IT-066) and a proton pump inhibitor (omeprazole) were used to determine whether these drugs alter the relative composition of active mitogens in gastric juice. RESULTS: Normal gastric juice significantly increased DNA synthesis. This activity was suppressed by antibody (87-88%). Both drugs increased EGF concentrations and activity dose-dependently IT-066 specifically increased total amount and activity of EGF. Approximately 50% of this activity was reduced by boiling or antibody. CONCLUSION: The major mitogenic activity of normal rat gastric juice depends on EGF, and antisecretory drugs enhance the mitogenic activity by preserving and including intraluminal mitogens than EGF.

Animals↗
PubMed1993

[The establishment of a monolayer culture system of guinea pig chief cells and an enzyme immunoassay system for guinea pig pepsinogen].

For the purpose of studying pepsinogen secretion from gastric chief cells, we established a monolayer culture system of guinea pig chief cells and an enzyme immunoassay (EIA) system specific for guinea pig pepsinogen. Dispersed chief cells were obtained from gastric mucosa of a guinea pig using collagenase, GEDTA, and Percoll solution, suspended in DMEM/F-12 (1/1 containing 10% FCS) media, and cultured for 70hr. Then the monolayer culture system was established. Pepsinogen was purified from gastric mucosa of a guinea pig using DEAE-Sephacel and Sephacryl S-200 columns. Antibody to pepsinogen was raised by immunizing rabbit with the purified pepsinogen. A two-site EIA system was then established using beta-galactosidase-labeled Fab' antibody. The EIA system showed sensitivity to measure above 1.5ng of guinea pig pepsinogen, and the monolayer culture system responded well to secretagogues. These systems are useful for studying pepsinogen secretion.

Animals↗