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K Ishiguro

Publications and source records attributed to K Ishiguro.

At least 19 recordsLinked to original sources
PubMed2006

Pit patterns in rectal mucosa assessed by magnifying colonoscope are predictive of relapse in patients with quiescent ulcerative colitis.

BACKGROUND: Relapse of ulcerative colitis is difficult to predict by routine colonoscopy. A high-resolution video-magnifying colonoscope with chromoscopy enables the observation of colorectal mucosal pit patterns. AIMS: To investigate the association of pit patterns as assessed by magnifying colonoscopy (MCS) with histological inflammation and mucosal chemokine activity in patients with quiescent ulcerative colitis, and to prospectively analyse the prognostic factors that may predict exacerbations. METHODS: MCS was performed in 113 patients with ulcerative colitis in remission. Pit patterns in the rectal mucosa were classified into four MCS grades on the basis of size, shape and arrangement. Mucosal interleukin (IL) 8 activity was measured in biopsy specimens of rectal mucosa and the specimens were assessed for histological disease activity. The patients were then followed until relapse or for a maximum of 12 months. Multivariate survival analysis was carried out to determine the independent predictors of clinical relapse. RESULTS: A positive correlation was identified between MCS grade, histological grade (p = 0.001) and mucosal IL8 activity (p<0.001). Multivariate proportional hazard model analysis showed that MCS grade was a significant predictor of relapse (relative risk 2.06, p = 0.001). Kaplan-Meier estimate of relapse during 12 months of follow-up was found to increase with increasing MCS grade, with values of 0% for grade 1, 21% for grade 2, 43% for grade 3 and 60% for grade 4. CONCLUSION: MCS grading is associated with the degree of histological inflammation and mucosal IL8 activity in patients with quiescent ulcerative colitis, and may predict the probability of subsequent disease relapse in patients with ulcerative colitis in remission.

Adolescent↗
PubMed2006

Reduction of mucin-1 gene expression associated with increased Escherichia coli adherence in the canine uterus in the early stage of dioestrus.

The relation between adherence of Escherichia coli and expression of mucin-1 (Muc1: an integral membrane mucin) mRNA in the endometrium was studied in beagle bitches at different stages of the oestrous cycle and in those with cystic endometrial hyperplasia/pyometra complex (pyometra). The number of E. coli adhering to the endometrium was low at pro-oestrus and oestrus and increased at the early stage (day 10) of dioestrus, corresponding to the implantation period; it declined thereafter. Adhesion of the organisms to endometrial epithelial cells collected at day 10 of dioestrus was inhibited by the addition of D-mannose. When endometrial epithelial cells collected at pro-oestrus were treated with hyaluronidase, an enzyme that digests mucins, the numbers of E. coli adhering to the cells tended to increase. With polymerase chain reaction analysis it was possible to detect Muc1 gene transcripts in the endometrium at all stages of the oestrous cycle, although the level of Muc1 mRNA decreased by day 10 of dioestrus. The levels of Muc1 mRNA in bitches with a clinical stage of pyometra were low and comparable to those at day 10 of dioestrus. The number of E. coli adhering to the endometrium and Muc1 mRNA levels in the endometrium were inversely correlated (r=-0.77, P<0.01). Immunohistochemical analysis showed little staining for Muc1 in the endometrial epithelia at day 10 of dioestrus and in bitches with pyometra. These results suggest that reduction of Muc1 expression is associated with increased E. coli adherence in the canine uterus at the early stage of dioestrus, possibly facilitating the development of pyometra.

Animals↗
PubMed2006

DNA hypermethylation in colorectal neoplasms and inflammatory bowel disease: a mini review.

DNA hypermethylation is one of major epigenetic changes. Hypermethylation of many genes has been reported to be related with carcinogenesis and tumor progression of colorectal cancer. Some genes including estrogen receptor is associated with ageing, and changes related with ageing may be accelerated in inflammatory bowel disease. Furthermore, fecal DNA methylation will be able to be used as a marker of colorectal cancer and inflammatory bowel disease. Evaluation of hypermethylation potentially contributes diagnosis of colorectal diseases.

Animals↗
PubMed2005

Epithelial and stromal genetic instability contributes to genesis of colorectal adenomas.

BACKGROUND: Previously, we indicated that stromal genetic instability might contribute to tumorigenesis of both sporadic and ulcerative colitis associated colorectal adenocarcinomas. Considering the established adenoma-adenocarcinoma sequence, in this study we analysed genetic instability in colorectal adenoma cells and surrounding stroma. METHODS: In 164 colorectal tumours (34 hyperplastic polyps, 38 tubular adenomas with low grade dysplasia (TA-L), 51 tubular adenomas with high grade dysplasia (TA-H), and 41 invasive carcinomas), epithelial and stromal genetic instability with National Cancer Institute standard microsatellite markers and chromosome 17 (Chr17) markers, were analysed by a combination of laser capture microdissection and GeneScan approaches. RESULTS: While frequencies of both loss of heterozygosity (LOH) and microsatellite instability (MSI) were extremely low in hyperplastic polyps, LOH in tubular adenomas was detected in both epithelial (TA-L 13.2%, TA-H 27.5%) and stromal (5.3% and 5.9%, respectively) elements, along with MSI (5.3% and 13.7%, and 5.3 and 5.9%, respectively). Frequencies of epithelial alterations were higher in TA-H than in TA-L, and greatest in the carcinoma group. On the other hand, frequencies of stromal LOH or MSI were almost constant (5.3% approximately 17.1%, 5.3% approximately 17.1%, respectively) in adenomas and invasive carcinomas. In addition, p53 was found to be significantly overexpressed in a greater proportion of TA-L with LOH than in those without genetic instability. CONCLUSION: The results indicate the presence of genetic alterations in stroma from an early stage of carcinogenesis, accompanied by stepwise increasing genetic instability of epithelia with progression to cancer. Thus microenvironmental changes due to genetic alteration in Chr17 markers in stromal cells may play an important role in colon adenoma and adenocarcinoma development.

Adenocarcinoma↗
PubMed2005

Interleukin 1B proinflammatory genotypes protect against gastro-oesophageal reflux disease through induction of corpus atrophy.

BACKGROUND AND AIMS: The relationship between Helicobacter pylori infection and gastro-oesophageal reflux disease (GORD) is controversial but it is accepted that GORD is associated with increased exposure to gastric acidity. The proinflammatory interleukin (IL)-1B polymorphisms increase the risk of hypochlorhydria and gastric atrophy. We examined the association between proinflammatory cytokine gene polymorphisms, presence of gastric atrophy, and risk of GORD in H pylori positive and negative subjects in Japan. METHODS: We studied 320 consecutive dyspeptic patients without peptic ulcers or cancers. GORD symptoms were scored using the Carlsson-Dent questionnaire and erosive oesophagitis was assessed endoscopically. H pylori infection was diagnosed by urea breath test, histological examination, and serology. Gastric atrophy was assessed histologically, and polymorphisms in the IL-1B, IL-10, and tumour necrosis factor alpha (TNF-A) genes were genotyped. RESULTS: Two hundred and eight patients were H pylori positive and 112 were negative. One hundred and eight (34%) were found to have erosive oesophagitis by endoscopic criteria (grade A: 78; grade B: 23; grade C: 6; grade D: 1). Erosive oesophagitis and GORD symptoms were significantly more common in H pylori negative compared with H pylori positive subjects (p<0.05). H pylori positive subjects were more likely to have corpus gastric atrophy than H pylori negative subjects (p<0.001). Among H pylori positive patients, those without erosive oesophagitis or GORD symptoms were significantly more likely to have corpus atrophy than subjects with erosive oesophagitis or GORD symptoms (p<0.05). Among H pylori positive patients, subjects homozygous for the proinflammatory allele IL-1B-511T had a significantly lower risk of erosive oesophagitis (odds ratio (OR) 0.06 (95% confidence interval (CI) 0.006-0.51); p=0.01) and GORD symptoms (OR 0.10 (95% CI 0.01-0.85); p=0.04) compared with those homozygous for the -511C allele, while none of the two other proinflammatory cytokine gene polymorphisms had significant correlations with erosive oesophagitis or GORD symptoms. CONCLUSIONS: A proinflammatory IL-1B genotype is associated with increased risk of atrophy and decreased risk of GORD in H pylori infected subjects in Japan. These data indicate that in some genetically predisposed subjects, H pylori infection may protect against GORD through induction of gastric atrophy.

Adult↗
PubMed2004

GP2/THP gene family of self-binding, GPI-anchored proteins forms a cluster at chromosome 7F1 region in mouse genome.

We investigated the genomic organization of pancreatic zymogen granule membrane-associated protein GP2, a GPI-anchored protein exhibiting self-aggregation at acidic pH, in order to construct a gene-knockout mouse. Cloning and analysis of lambda clones encoding GP2 from 129 Svj mouse genomic DNA libraries showed that the GP2 gene spans about 16.8 kb and includes 11 exons. Identifiable functional domains including a signal sequence, an EGF-like motif, a putative condensing ZP domain, a GPI-anchor attachment site, and a transmembrane sequence for GPI anchoring are encoded in separate exons. Using FISH, the GP2 gene was mapped to mouse chromosome 7F1 near the gene for THP, a GP2 homolog expressed in the cells of thick ascending loop of Henle (TALH) in the kidney. Further analysis of the mouse genome revealed that the THP and GP2 genes are adjacent to one another and are separated by only 3.5 kb in the 7F1 locus. Additionally, the overall structure of the THP gene, 16.2kb with 11 exons, was strikingly similar to that of GP2. This finding suggests that the GP2 and THP genes were generated by gene duplication and evolved separately to acquire regulatory elements leading to tissue-specific expression. Comparative analysis revealed that the 5' flanking region of the THP gene is similar to the first intron of NKCC2, a TALH cell-specific ion-transporter gene. The promoter region of the GP2 gene shares cis-elements found in other pancreas-specific genes. Using this genetic information, a GP2 null mutation was successfully introduced into an ES cell line, and an animal model was established without disruption of THP expression.

Animals↗
PubMed2002

Regeneration of transformed verbena (Verbena x hybrida) by Agrobacterium tumefaciens.

Verbena (Verbena x hybrida), an important floricultural species, was successfully regenerated from stem segments on Murashige and Skoog's basal medium supplemented with thidiazuron and indole-3-acetic acid. A transformation system was developed using cvs. Temari Scarlet, Temari Sakura, Tapien Rose and TP-P2. Agrobacterium tumefaciens strain Agl0 harboring the sGFP gene was infected into stem segments. Transformation efficiency was improved by evaluating and manipulating the age of the plant material, the concentration of kanamycin in the medium during selection, and the length of the culture period in the dark. After 2-3 months of culture on the selection medium, GFP-positive shoots were obtained in all four of the cultivars tested. These shoots were successfully acclimated and set flowers within 2-3 months in a greenhouse. GFP was expressed in all of the organs including the floral parts. Stable genomic transformation was confirmed by Southern blot analysis. No morphological differences were observed between the transformed plants and their host plants.

Agrobacterium tumefaciens↗
PubMed2001

Syndecan-4 deficiency leads to high mortality of lipopolysaccharide-injected mice.

Syndecan-4 is a transmembrane heparan sulfate proteoglycan belonging to the syndecan family. Following intraperitoneal injection of lipopolysaccharide (LPS), syndecan-4-deficient mice exhibited high mortality compared with wild-type controls. Severe endotoxin shock was observed in the deficient mice: systolic blood pressure and left ventricular fractional shortening were lower in the deficient mice than in the wild-type controls 9 h after LPS injection. Although histological examinations revealed no apparent differences between two groups, the plasma level of interleukin (IL)-1beta was higher in the deficient mice than in the wild-type controls 9 h after LPS injection. Consistent with the regulatory roles of syndecan-4, its expression in monocytes and endothelial cells of microvasculature increased in the wild-type mice after LPS administration. Although IL-1beta was produced to the same extent by macrophages from syndecan-4-deficient and wild-type mice after LPS stimulation, inhibition of its production by transforming growth factor-beta1 was impaired in the syndecan-4-deficient macrophages. These results indicate that syndecan-4 could be involved in prevention of endotoxin shock, at least partly through the inhibitory action of transforming growth factor-beta1 on IL-1beta production.

Animals↗
PubMed2001

Inhibition of protein phosphatase 2A overrides tau protein kinase I/glycogen synthase kinase 3 beta and cyclin-dependent kinase 5 inhibition and results in tau hyperphosphorylation in the hippocampus of starved mouse.

Hyperphosphorylated tau is the major component of paired helical filaments in neurofibrillary tangles found in Alzheimer's disease (AD) brain. Starvation of adult mice induces tau hyperphosphorylation at many paired helical filaments sites and with a similar regional selectivity as those in AD, suggesting that a common mechanism may be mobilized. Here we investigated the mechanism of starvation-induced tau hyperphosphorylation in terms of tau kinases and Ser/Thr protein phosphatases (PP), and the results were compared with those reported in AD brain. During starvation, tau hyperphosphorylation at specific epitopes was accompanied by decreases in tau protein kinase I/glycogen synthase kinase 3 beta (TPKI/GSK3 beta), cyclin-dependent kinase 5 (cdk5), and PP2A activities toward tau. These results demonstrate that the activation of TPKI/GSK3 beta and cdk5 is not necessary to obtain hyperphosphorylated tau in vivo, and indicate that inhibition of PP2A is likely the dominant factor in inducing tau hyperphosphorylation in the starved mouse, overriding the inhibition of key tau kinases such as TPKI/GSK3 beta and cdk5. Furthermore, these data give strong support to the hypothesis that PP2A is important for the regulation of tau phosphorylation in the adult brain, and provide in vivo evidence in support of a central role of PP2A in tau hyperphosphorylation in AD.

Alzheimer Disease↗
PubMed2001

Involvement of cyclin dependent kinase5 activator p25 on tau phosphorylation in mouse brain.

P35 or its truncated fragment p25 is required for cyclin dependent kinase (Cdk)5 activation. It has been reported that p25 is accumulated in the brain of Alzheimer's disease (AD) patients and that p25/Cdk5 induces high phosphorylation of tau and apoptosis in cultured neurons (Nature 402 (1999) 615). Our investigation of AD brain did not show specific accumulation of p25. Exposure to Ca ionophore (A23187) at 10(-6) M induced p25 accumulation in rat primary hippocampal neurons, causing neuronal death without showing hyperphosphorylation of tau. Transgenic mice expressing p25 showed the accumulation of p25 but neither hyperphosphorylation of tau nor neuronal death was shown in these mice. The feature of these mice was the progression of cell growth in pituitary gland. These results suggest that overexpression of p25 lead to the activation of cell cycle but not to the direct phosphorylation of tau.

Aged↗
PubMed2001

Caveolin-2 is targeted to lipid droplets, a new "membrane domain" in the cell.

Caveolin-1 and -2 constitute a framework of caveolae in nonmuscle cells. In the present study, we showed that caveolin-2, especially its beta isoform, is targeted to the surface of lipid droplets (LD) by immunofluorescence and immunoelectron microscopy, and by subcellular fractionation. Brefeldin A treatment induced further accumulation of caveolin-2 along with caveolin-1 in LD. Analysis of mouse caveolin-2 deletion mutants revealed that the central hydrophobic domain (residues 87-119) and the NH(2)-terminal (residues 70-86) and COOH-terminal (residues 120-150) hydrophilic domains are all necessary for the localization in LD. The NH(2)- and COOH-terminal domains appeared to be related to membrane binding and exit from ER, respectively, implying that caveolin-2 is synthesized and transported to LD as a membrane protein. In conjunction with recent findings that LD contain unesterified cholesterol and raft proteins, the result implies that the LD surface may function as a membrane domain. It also suggests that LD is related to trafficking of lipid molecules mediated by caveolins.

Animals↗
PubMed2001

Abeta amyloidosis induces the initial stage of tau accumulation in APP(Sw) mice.

To clarify how Abeta deposits induce secondary tauopathy, the presence of phosphorylated tau, glycogen synthase kinase 3alpha (GSK3alpha), GSK3beta, cyclin-dependent kinase 5 (CDK5), mitogen-activated protein kinase (MAPK) and fyn were examined in the Tg2576 brain showing substantial brain Abeta amyloidosis and behavioral abnormalities. Phosphorylated tau at Ser199, Thr231/Ser235, Ser396 and Ser413 accumulated in the dystrophic neurites of senile plaques. The major kinase for tau phosphorylation was GSK3beta. Smaller contributions of GSK3alpha, CDK5 and MAPK were suggested. Thus, brain Abeta amyloidosis has a potential role in the induction of tauopathy leading to the mental disturbances of Alzheimer's disease.

Alzheimer Disease↗
PubMed2001

Synergistic contributions of cyclin-dependant kinase 5/p35 and Reelin/Dab1 to the positioning of cortical neurons in the developing mouse brain.

Cyclin-dependent kinase (Cdk) 5 is a unique member of the Cdk family, because Cdk5 kinase activity is detected only in the nervous tissue. Two neuron-specific activating subunits of Cdk5, p35 and p39, have been identified. Overlapping expression pattern of these isoforms in the embryonic mouse brain and the significant residual Cdk5 kinase activity in brain homogenate of the p35-/- mice indicate the redundant functions of the Cdk5 activators in vivo. Severe neuronal migration defects in p35-/-Cdk5 +/- mice further support the idea that the redundant expression of the Cdk5 activators may cause a milder phenotype in p35-/- mice compared with Cdk5-/- mice. Mutant mice lacking either Cdk5 or p35 exhibit certain similarities with Reelin/Dab1-mutant mice in the disorganization of cortical laminar structure in the brain. To elucidate the relationship between Cdk5/p35 and Reelin/Dab1 signaling, we generated mouse lines that have combined defects of these genes. The addition of heterozygosity of either Dab1 or Reelin mutation to p35-/- causes the extensive migration defects of cortical neurons in the cerebellum. In the double-null mice of p35 and either Dab1 or Reelin, additional migration defects occur in the Purkinje cells in the cerebellum and in the pyramidal neurons in the hippocampus. These additional defects in neuronal migration in mice lacking both Cdk5/p35 and Reelin/Dab1 indicate that Cdk5/p35 may contribute synergistically to the positioning of the cortical neurons in the developing mouse brain.

Adaptor Proteins, Signal Transducing↗
PubMed2001

A proteomics approach towards understanding blast fungus infection of rice grown under different levels of nitrogen fertilization.

Proteins extracted from leaf blades of rice plants infected with blast fungus, Magnaporthe grisea, were separated by two-dimensional polyacrylamide gel electrophoresis. The separated proteins were electroblotted onto a polyvinylidene difluoride membrane, and 63 proteins were analyzed by a gas-phase protein sequencer. The N-terminal amino acid sequences of 33 out of 63 proteins were determined in this manner. N-terminal regions of the remaining proteins could not be sequenced. The internal amino acid sequences of 12 proteins were determined by sequence analysis of peptides obtained by the Cleveland peptide mapping method. The amino acid sequences were compared with those of known plant and animal protein sequences to understand the nature of these proteins. As expected, leaf blades revealed predominantly the presence of photosynthetic proteins. Using this experimental approach named as proteome analysis, the functional proteins during blast fungus infection of rice with different levels of nitrogen nutrient were analyzed. Twelve proteins which appeared to change with different levels of nitrogen nutrient were identified. It was revealed that the level of ribulose-1,5-bisphosphate carboxylase/oxygenase was increased by top-dressing with nitrogen nutrient. Additionally, the pathogenesis related protein were observed following blast fungus infection using immunoblot analysis. It was conjectured that these proteins might be involved in incompatible interaction in rice plants following blast fungus infection. The information obtained on the amino acid sequences and antibodies interaction is expected to be helpful in predicting the function of these proteins.

Electrophoresis, Gel, Two-Dimensional↗
PubMed2001

Large-scale, multicenter study of cerebrospinal fluid tau protein phosphorylated at serine 199 for the antemortem diagnosis of Alzheimer's disease.

We surveyed a total of 570 cerebrospinal fluid (CSF) samples from a variety of diseases, including Alzheimer's disease (AD; n = 236), non-AD-demented and nondemented diseases (n = 239), and normal controls (n = 95) to quantitate levels of tau protein phosphorylated at serine 199 (CSF/phospho-tau199) by a recently established sandwich ELISA. The CSF/phospho-tau199 levels in the AD group were significantly elevated compared to those in all the other non-AD groups. Receiver operating characteristics curves showed that the diagnostic sensitivity and specificity for the AD group vs all the other non-AD groups using the CSF/phospho-tau199 were 85.2% and 85.0%, respectively. Furthermore, there was a significant positive correlation between CSF/phospho-tau199 and CSF/total-tau levels in the AD group. Elevated CSF/phospho-tau199 in the AD group was noted irrespective of age, gender, dementia severity, and number of apolipoprotein E4 alleles. Thus, we suggest that CSF/phospho-tau199 may be a novel and logical biomarker in supporting antemortem diagnosis of AD.

Aged↗
PubMed2001

Brain Abeta amyloidosis in APPsw mice induces accumulation of presenilin-1 and tau.

APPsw transgenic mice (Tg2576) overproducing mutant amyloid beta protein precursor (betaAPP) show substantial brain Abeta amyloidosis and behavioural abnormalities. To clarify the subsequent abnormalities, the disappearance of neurons and synapses and dystrophic neurite formation with accumulated proteins including hyperphosphorylated tau were examined. Tg2576 demonstrated substantial giant core plaques and diffuse plaques. The number of neurons was significantly decreased in the areas containing the amyloid cores compared with all other areas and corresponding areas in non-transgenic littermates in sections visualized by Nissl plus Congo red double staining (p<0.001). The presynaptic protein alpha-synuclein and postsynaptic protein drebrin were also absent in the amyloid cores. betaAPP and presenilin-1 were accumulated in dystrophic neurites in and around the core plaques. Tau phosphorylated at five independent sites was detected in the dystrophic neurites in the amyloid cores. Thus, the giant core plaques replaced normal brain tissues and were associated with subsequent pathological features such as dystrophic neurites and the appearance of hyperphosphorylated tau. These findings suggest a potential role for brain Abeta amyloidosis in the induction of secondary pathological steps leading to mental disturbance in Alzheimer's disease.

Alzheimer Disease↗