A case of malabsorption syndrome caused by isosporiasis in an immunocompetent patient.
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Adult↗
Biomedical subjects
Akiko Tanaka
Publications and source records attributed to Akiko Tanaka.
NMR assignment of the SH2 domain from the human feline sarcoma oncogene FES.
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Humans↗
The CAP-Gly domain of CYLD associates with the proline-rich sequence in NEMO/IKKgamma.
CYLD was originally identified as the human familial cylindromatosis tumor suppressor. Recently, it was reported that CYLD directly interacts with NEMO/IKKgamma and TRAF2 in the NF-kappaB signaling pathway. The two proteins bind to a region of CYLD that contains a Cys-box motif and the third cytoskeleton-associated protein-glycine conserved (CAP-Gly) domain. Here we report that the third CAP-Gly domain of CYLD specifically interacts with one of the two proline-rich sequences of NEMO/IKKgamma. The tertiary structure of the CAP-Gly domain shares the five-stranded beta sheet topology with the SH3 domain, which is well known as a proline-rich sequence-recognition domain. However, chemical shift mapping revealed that the peptide binding site of the CAP-Gly domain is formed without the long peptide binding loop characteristic of the SH3 domain. Therefore, CAP-Gly is likely to be a novel proline-rich sequence binding domain with a mechanism different from that of the SH3 domain.
Amino Acid Sequence↗
Functional mechanism underlying COX-2 expression following administration of indomethacin in rat stomachs: importance of gastric hypermotility.
The expression of COX-2 is up-regulated in the rat stomach after administration of indomethacin, and the inhibition of this enzyme may be a key to NSAID-induced gastric damage. The present study investigated the mechanism for COX-2 expression induced in the rat stomach by indomethacin, in relation with the ulcerogenic processes. The animals were given indomethacin or SC-560 p.o., and the gastric mucosa was examined 8 hr later. Indomethacin decreased the mucosal PGE2 content and produced gross damage with gastric hypermotility and the expression of COX-2 mRNA in the mucosa. Although SC-560 did not produce damage, this agent caused a decrease in the PGE2 content and an increase in gastric motility as well as the up-regulation of COX-2 expression, and provoked damage in the presence of rofecoxib. Gastric lesions induced by indomethacin were prevented by both atropine (even in the presence of exogenous HCl) and omeprazole, although the hypermotility response was inhibited only by atropine. The COX-2 expression induced by indomethacin or SC-560 was inhibited by atropine, even in the presence of exogenous HCl, while omeprazole had no effect. The mucosal PGE2 content was decreased by SC-560 at 2 hr but recovered 8 hr later, and this recovery of PGE2 was attenuated by both atropine and rofecoxib but not omeprazole. These results suggested that the COX-2 expression in the stomach following treatment with indomethacin is functionally associated with gastric hypermotility response induced by COX-1 inhibition. Luminal acid does not play a role in the up-regulation of COX-2 expression in the stomach following administration of indomethacin.
Animals↗
NMR assignment of the hypothetical ENTH-VHS domain At3g16270 from Arabidopsis thaliana.
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Arabidopsis↗
NMR assignment of the hypothetical rhodanese domain At4g01050 from Arabidopsis thaliana.
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Arabidopsis↗
Preparation of Escherichia coli cell extract for highly productive cell-free protein expression.
As structural genomics and proteomics research has become popular, the importance of cell-free protein synthesis systems has been realized for high-throughput expression. Our group has established a high-throughput pipeline for protein sample preparation for structural genomics and proteomics by using cell-free protein synthesis. Among the many procedures for cell-free protein synthesis, the preparation of the cell extract is a crucial step to establish a highly efficient and reproducible workflow. In this article, we describe a detailed protocol for E. coli cell extract preparation for cell-free protein synthesis, which we have developed and routinely use. The cell extract prepared according to this protocol is used for many of our cell-free synthesis applications, including high-throughput protein expression using PCR-amplified templates and large-scale protein production for structure determinations.
Cell Fractionation↗
Solution structure of the RWD domain of the mouse GCN2 protein.
GCN2 is the alpha-subunit of the only translation initiation factor (eIF2alpha) kinase that appears in all eukaryotes. Its function requires an interaction with GCN1 via the domain at its N-terminus, which is termed the RWD domain after three major RWD-containing proteins: RING finger-containing proteins, WD-repeat-containing proteins, and yeast DEAD (DEXD)-like helicases. In this study, we determined the solution structure of the mouse GCN2 RWD domain using NMR spectroscopy. The structure forms an alpha + beta sandwich fold consisting of two layers: a four-stranded antiparallel beta-sheet, and three side-by-side alpha-helices, with an alphabetabetabetabetaalphaalpha topology. A characteristic YPXXXP motif, which always occurs in RWD domains, forms a stable loop including three consecutive beta-turns that overlap with each other by two residues (triple beta-turn). As putative binding sites with GCN1, a structure-based alignment allowed the identification of several surface residues in alpha-helix 3 that are characteristic of the GCN2 RWD domains. Despite the apparent absence of sequence similarity, the RWD structure significantly resembles that of ubiquitin-conjugating enzymes (E2s), with most of the structural differences in the region connecting beta-strand 4 and alpha-helix 3. The structural architecture, including the triple beta-turn, is fundamentally common among various RWD domains and E2s, but most of the surface residues on the structure vary. Thus, it appears that the RWD domain is a novel structural domain for protein-binding that plays specific roles in individual RWD-containing proteins.
Amino Acid Sequence↗
Inhibition of small-conductance Cl- channels by the interleukin-1beta-stimulated production of superoxide in rabbit gastric parietal cells.
We have shown previously that the G protein-coupled production of superoxide anion (O2-) leads to closure of small-conductance Cl- channels (0.3-0.4 pS) in the basolateral membrane of rabbit parietal cells. In the present study, effects of interleukin-1beta (IL-1beta) on the Cl- channel were investigated. In the whole-cell patch-clamp recording, IL-1beta (0.3-10 ng ml-1) inhibited the whole-cell Cl- current recorded from a parietal cell within isolated rabbit gastric glands. Variance noise analysis of the whole-cell Cl- current showed that the single channel conductance of the Cl- channel that is sensitive to IL-1beta is 0.37 pS. The IL-1beta (1 ng ml-1)-induced decrease of the Cl- current was abolished by anti-IL-1beta antibody (2 microg ml-1), recombinant IL-1 receptor antagonist (500 ng ml-1), GDPbetaS (500 microM) and superoxide dismutase (100 units ml-1), a scavenger of O2-. Northern blot analysis showed that the mRNA of the IL-1 receptor was selectively expressed in rabbit gastric parietal cells. In the dihydrofluorescein diacetate-loaded single parietal cells in gastric glands, IL-1beta (0.3-10 ng ml-1) stimulated the production of oxygen radicals. Y-27632 (1-10 microM), a specific Rho-kinase inhibitor, and fluvastatin (10 microM), an indirect inhibitor for Rho proteins, significantly inhibited the IL-1beta-induced effects on the channel activity and production of oxygen radicals. IL-1beta (0.3-10 ng ml-1) activated Rho in the parietal cells. These results indicate that IL-1beta binds to the IL-1 receptor of gastric parietal cells and inhibits the small-conductance Cl- channel via the G protein-mediated Rho/Rho-kinase-dependent production of O2-.
Acute-Phase Proteins↗
Morphology of aging lung in F344/N rat: alveolar size, connective tissue, and smooth muscle cell markers.
This study investigated the morphological changes of lungs in F344/N rats (9-36 months old). We initially examined general and quantitative morphological changes, and then we used immunohistochemistry to detect distributional changes in collagen subtypes (types I, III, and IV) and smooth muscle cell (SMC) markers (alpha-smooth muscle actin (ASMA), gamma-smooth muscle actin (GSMA), desmin, and vimentin) in the lungs. In 24-month-old rats, alveolar ducts and alveolar sacs were enlarged, and alveoli were wider and shallower than in younger animals. In old rats (>/=27 months), terminal and respiratory bronchioles and alveolar ducts were dilated and alveoli were more extended than in 24-month-old rats. No age-related distributional changes were observed for collagen types I, III, and IV as revealed by immunohistochemistry, or elastin as revealed by resorsin fuchsin. SMCs in the extra- and intrapulmonary bronchi were immunoreactive for ASMA, GSMA, and desmin, but not for vimentin at all ages. In old rats (>/=27 months), SMCs were loosely arranged in comparison with younger animals, and stainability for GSMA and desmin was decreased. In the respiratory bronchioles and alveolar ducts, a few cells immunoreactive for ASMA and vimentin were observed in the smooth muscle aggregations of the alveolar orifice in rats younger than 12 months. In older rats (>20 months), cells immunoreactive for ASMA and vimentin were increased in septal tips. In conclusion, extension of distal airways and immunohistochemical changes of SMC markers in F344/N rat lungs were evident by approximately 24 months of age, but there was no apparent change in connective tissue morphology.
Actins↗
Characteristics of gastroesophageal reflux disease in Japan: increased prevalence in elderly women.
The aim of this study was to examine the characteristics of gastroesophageal reflux disease in Japan. We evaluated the correlation between clinical symptoms and endoscopic findings in an age- and sex-specific manner. This study included 6010 Japanese subjects who had not received medication or undergone laparotomy for gastrointestinal disease. All subjects were questioned in regard to clinical symptoms by paramedical personnel before endoscopic examination. Esophageal mucosal breaks were evaluated according to the Los Angeles Classification of Esophagitis. The ratio of subjects with each complaint to all subjects is as follows: heartburn, 27.0%; dysphagia, 16.9%; odynophagia, 19.2%; acid regurgitation, 7.1%. The proportion of each grade was grade A, 9.6%; grade B, 4.6%; and grade C + D, 2.0%. The most common related symptom for endoscopic esophagitis among these four symptoms was heartburn (odds ration, 2.5), although about 40% of subjects with severe esophagitis of grade C or D did not complain of heartburn. Regarding odynophagia, acid regurgitation, and dysphagia, odds ratios were about 1.0. The age-related ratio of esophagitis and severe disease with grades C and D increased in women over 60 years of age. An age-related slouched position was related to the increased esophagitis in these elderly women. Male subjects whose body mass index was more than 25 tended to show a greater prevalence in the age group 30-50 years. The prevalence of hiatal herniation increased in an age-related manner. These data indicate the characteristics of esophagitis in Japan are as follows: (1) the prevalence of reflux esophagitis is about 15% and most of these cases are grade A or B; and (2) the prevalence of severe esophagitis increases in older women, who do not always complain of clinical symptoms.
Adult↗
16,16-Dimethyl prostaglandin E2 inhibits indomethacin-induced small intestinal lesions through EP3 and EP4 receptors.
We evaluated the effect of various PGE analogs specific to EP receptor subtypes on indomethacin-induced small intestinal lesions in rats and investigated the relationship of EP receptor subtype with the PGE action using EP receptor knockout mice. Animals were administered indomethacin subcutaneously, and they were killed 24 hr later. 16,16-dimethyl prostaglandin E2 (dmPGE2) or various EP agonists were administered intravenously 10 min before indomethacin. Indomethacin caused hemorrhagic lesions in the rat small intestine, accompanied with an increase in intestinal motility and the number of enteric bacteria as well as iNOS and MPO activities. Prior administration of dmPGE2 dose-dependently prevented intestinal lesions, together with inhibition of those functional changes. These effects of dmPGE2 were mimicked by prostanoids (ONO-NT-012 and ONO-AE1-329), only specific to EP3 or EP4 receptors, although the intestinal motility was inhibited only by ONO-AE1-329. Intestinal mucus secretion and fluid accumulation were decreased by indomethacin but enhanced by dmPGE2, ONO-NT-012, and ONO-AE1-329 at the doses that prevented intestinal lesions. Indomethacin also caused intestinal lesions in both wild-type and knockout mice lacking EP1 or EP3 receptors, yet the protective action of dmPGE2 was observed in wild-type and EP1 receptor knockout mice but not the mice lacking EP3 receptors. These results suggest that the intestinal cytoprotective action of PGE2 against indomethacin is mediated by EP3/EP4 receptors and that this effect is functionally associated with an increase of mucus secretion and enteropooling as well as inhibition of intestinal hypermotility, the former two processes mediated by both EP3 and EP4 receptors, and the latter by EP4 receptors.
16,16-Dimethylprostaglandin E2↗
Prevention by parenteral aspirin of indomethacin-induced gastric lesions in rats: mediation by salicylic acid.
Nonsteroidal antiinflammatory drugs (NSAIDs) produce gastric damage in experimental animals, irrespective of the route of administration. However, aspirin (ASA) causes damage only when it is given orally. In the present study, we examined the gastric ulcerogenic effect of subcutaneously administered ASA in rats, in comparison with various NSAIDs, and investigated the reason why ASA does not cause damage in the stomach, in relation to its metabolite salicylic acid (SA). Since the antiinflammatory action of SA is known to be mediated, partly, by endogenous adenosine (AD), we also examined the possible involvement of AD in the protective action of SA. Various NSAIDs (indomethacin, flurbiprofen, naproxen, diclrofenac, ASA, SA) were administered subcutaneously, and the gastric mucosa was examined macroscopically 4 hr later. All NSAIDs tested, except ASA and SA, caused hemorrhagic lesions in the stomach, with a marked gastric hypermotility and a decrease of mucosal PGE2 contents. These ulcerogenic and motility responses caused by NSAIDs were blocked by pretreatment with atropine or PGE2. ASA, although inhibiting PGE2 generation, caused neither hypermotility nor damage in the stomach. On the other hand, SA alone inhibited basal gastric motility without any effect on mucosal PGE2 contents, and this agent, when given together with indomethacin, prevented gastric hypermotility and lesion formation in response to indomethacin, without affecting the reduced PGE2 contents. Likewise, ASA inhibited these responses to indomethacin, yet the effects appeared later than those of SA. Following administration of ASA, the blood SA levels reached a peak within 30 min and remained elevated for 4 hr. In addition, the protective effect of SA was not significantly influenced by either the AD deaminase or the AD-receptor antagonists. These results suggest that the failure of parenteral ASA to induce gastric damage may be explained by a protective action of SA metabolized from ASA. SA has a cytoprotective action against NSAID-induced gastric lesions, and this action is not mediated by endogenous AD but may be functionally associated with inhibition of the gastric motility response.
Adenosine↗
Role of cyclooxygenase (COX)-1 and COX-2 inhibition in nonsteroidal anti-inflammatory drug-induced intestinal damage in rats: relation to various pathogenic events.
We recently reported that cyclooxygenase (COX)-2 expression was up-regulated in the rat small intestine after administration of indomethacin, and this may be a key to nonsteroidal anti-inflammatory drug (NSAID)-induced intestinal damage. In the present study, we investigated the effect of inhibiting COX-1 or COX-2 on various intestinal events occurring in association with NSAID-induced intestinal damage. Rats without fasting were treated with indomethacin, SC-560 (a selective COX-1 inhibitor), rofecoxib (a selective COX-2 inhibitor), or SC-560 plus rofecoxib, and the following parameters were examined in the small intestine: the lesion score, the enterobacterial number, myeloperoxidase (MPO) and inducible nitric-oxide synthase (iNOS) activity, and intestinal motility. Indomethacin decreased mucosal prostaglandin (PG)E2 content and caused damage in the intestine within 24 h, accompanied by an increase in intestinal contractility, bacterial numbers, and MPO as well as iNOS activity, together with the up-regulation of COX-2 and iNOS mRNA expression. Neither SC-560 nor rofecoxib alone caused intestinal damage, but their combined administration produced lesions. SC-560, but not rofecoxib, caused intestinal hypermotility, bacterial invasion, and COX-2 as well as iNOS mRNA expression, yet the iNOS and MPO activity was increased only when rofecoxib was also administered. Although SC-560 inhibited the PG production, the level of PGE2 was restored 6 h later, in a rofecoxib-dependent manner. We conclude that inhibition of COX-1, despite causing intestinal hypermotility, bacterial invasion, and iNOS expression, up-regulates the expression of COX-2, and the PGE2 produced by COX-2 counteracts deleterious events, and maintains the mucosal integrity. This sequence of events explains why intestinal damage occurs only when both COX-1 and COX-2 are inhibited.
Animals↗
Up-regulation of cyclooxygenase-2 by inhibition of cyclooxygenase-1: a key to nonsteroidal anti-inflammatory drug-induced intestinal damage.
Nonsteroidal anti-inflammatory drugs (NSAIDs) induce gastrointestinal ulceration as the adverse reaction. This effect of NSAIDs is attributable to endogenous prostaglandin (PG) deficiency caused by inhibition of cyclooxygenase (COX), yet the relation between COX inhibition and the gastrointestinal ulcerogenic property of NSAIDs remains controversial. Using selective COX inhibitors, we examined whether inhibition of COX-1 or COX-2 alone is sufficient for induction of intestinal damage in rats. Various COX inhibitors were administered p.o. in rats, and the animals were killed 24 h later. Mucosal PGE2 levels were determined by enzyme immunoassay, whereas the gene expression of COX isozymes was examined by reverse transcription-polymerase chain reaction. Nonselective COX inhibitors such as indomethacin inhibited PGE2 production and caused damage in the small intestine. Selective COX-2 inhibitors (rofecoxib or celecoxib) had no effect on the generation of PG, resulting in no damage. A selective COX-1 inhibitor (SC-560) did not cause damage, despite reducing PGE2 content. However, the combined administration of COX-1 and COX-2 inhibitors provoked intestinal damage with an incidence of 100%. COX-2 was up-regulated in the small intestine after administration of SC-560, and the PGE2 content was restored 6 h later, in a rofecoxib-dependent manner. The intestinal lesions induced by SC-560 plus rofecoxib were significantly prevented by later administration of 16,16-dimethyl PGE2. These results suggest that the intestinal ulcerogenic property of NSAID is not accounted for solely by inhibition of COX-1 and requires inhibition of COX-2 as well. The inhibition of COX-1 up-regulates COX-2 expression, and this may be a key to NSAID-induced intestinal damage.
Animals↗
Mechanisms by which endogenous glucocorticoid protects against indomethacin-induced gastric injury in rats.
We investigated the mechanisms underlying the protective action of glucocorticoids against indomethacin-induced gastric lesions. One-week adrenalectomized rats with or without corticosterone replacement (4 mg/kg sc) were administered indomethacin (25 mg/kg sc), and gastric secretion (acid, pepsin, and mucus), motility, microvascular permeability, and blood glucose levels were examined. Indomethacin caused gastric lesions in sham-operated rats, with an increase in gastric motility and microvascular permeability as well as a decrease in mucus secretion. Adrenalectomy significantly worsened the lesions and potentiated these functional disorders. Glucose levels were lowered by indomethacin in sham-operated rats, and this response was enhanced by adrenalectomy. The changes observed in adrenalectomized rats were prevented by supplementations of corticosterone at a dose mimicking the indomethacin-induced rise in corticosterone, whereas the protective effect of corticosterone was attenuated by RU-38486, a glucocorticoid receptor antagonist. We conclude that the gastroprotective action of endogenous glucocorticoids may be provided by their support of glucose homeostasis and inhibitory effects on enhanced gastric motility and microvascular permeability as well as maintaining the production of mucus.
Adrenalectomy↗
Pathogenic importance of intestinal hypermotility in NSAID-induced small intestinal damage in rats.
BACKGROUND/AIM: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin produce damage in the small intestine as a major adverse reaction. We examined the effect of various NSAIDs on intestinal motility and investigated the pathogenic importance of motility changes in the intestinal ulcerogenic response to indomethacin in rats. METHODS: Animals without fasting were given various NSAIDs (indomethacin 10 mg/kg, diclofenac 40 mg/kg, flurbiprofen 20 mg/kg, naproxen 40 mg/kg) s.c., and in the case of indomethacin, the following parameters were examined in the small intestine 24 h later; the lesion score, the number of enterobacteria and myeloperoxidase (MPO) as well as inducible nitric oxide (iNOS) activity. Intestinal motility was monitored as intraluminal pressure recordings using a balloon under anesthesia. RESULTS: All NSAIDs tested decreased mucosal PGE(2) levels and produced hemorrhagic lesions in the small intestine, accompanied by intestinal hypermotility. As representative of NSAIDs, indomethacin also increased the extent of enterobacterial invasion and MPO as well as iNOS activity before the occurrence of intestinal damage, and the hypermotility response was observed earlier than the onset of any other event caused by this agent. The intestinal lesions induced by indomethacin were prevented by either supplementation with dmPGE(2), inhibition of bacterial invasion with ampicillin or inhibition of iNOS activity with aminoguanidine, while the hypermotility response was prevented by dmPGE(2) only. In addition, the observed effects of dmPGE(2) were all mimicked by atropine when the intestinal hypermotility was suppressed by this agent. CONCLUSION: These results suggest the pathogenic importance of intestinal hypermotility in the intestinal ulcerogenic response to NSAIDs in rats and show that this event is critical for the occurrence of enterobacterial invasion under PG deficiency, followed by various inflammatory changes and damage in the mucosa. This study also suggests that the antispasmodic drug is protective against NSAID-induced intestinal lesions.
Animals↗
Healing of duodenal ulcers is not impaired by indomethacin or rofecoxib, the selective COX-2 inhibitor, in rats.
BACKGROUND/AIM: Studies have demonstrated an important role for endogenous PG and NO in the healing of chronic gastric ulcers. We investigated the effects of COX and NOS inhibitors on the healing of duodenal ulcers, in comparison with gastric ulcers, in rats. METHODS: Gastric and duodenal ulcers were induced by serosal application of acetic acid (0.1 ml of 100% acetic acid) for 60 and 20 s, respectively. Indomethacin (a nonselective COX inhibitor) or rofecoxib (a selective COX-2 inhibitor) was given p.o. once daily for 14 days from 3 days after ulcer induction, while N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) or aminoguanidine (a relatively selective iNOS inhibitor) was given s.c. twice daily during this period. RESULTS: Both gastric and duodenal ulcers induced by acetic acid healed spontaneously within 17 days to a minimal size. Daily administration of indomethacin or rofecoxib significantly delayed the healing of gastric but not duodenal ulcers. In contrast, the healing of both gastric and duodenal ulcers was delayed by repeated administration of either L-NAME or aminoguanidine. Ulceration markedly increased the PGE(2) content of the ulcerated mucosa in both the stomach and duodenum, and the increased PG biosynthetic response was inhibited by either indomethacin or rofecoxib in both tissues. The expression of both COX-2 and iNOS mRNAs was upregulated in the ulcerated mucosa of the stomach and duodenum. CONCLUSION: These results suggest that COX-2/PG is actively involved in the healing of gastric but not duodenal ulcers, although the mRNA for COX-2 is expressed in the duodenal mucosa after ulceration, as potently as in the gastric mucosa. In contrast, NO produced by both cNOS and iNOS plays a role in the healing of both gastric and duodenal ulcers.
Animals↗