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Biomedical subjects

H Iwamoto

Publications and source records attributed to H Iwamoto.

At least 55 records · Page 3Linked to original sources
PubMed2001

Immunochemical assay of hemoglobin with N(epsilon)-(carboxymethyl)lysine at lysine 66 of the beta chain.

BACKGROUND: N(epsilon)-(Carboxymethyl)lysine (CML), a well-characterized and major advanced glycation end product structure, is produced via a Maillard reaction by nonenzymatic glycation and/or oxidation. Although few of the carboxymethylation sites of lysine residues on proteins have been identified, it is known that the possible lysine glycation site in hemoglobin (Hb) is Lys-66 on the beta chain. We aimed to develop an assay for the Hb with a CML (CML-Hb) site specific to Lys-66 on the Hb beta chain and to determine whether the lysine residue at that site is carboxymethylated. METHODS: Ala-His-Gly-Lys-Lys(CM)-Val-Leu-Gly-Ala-Phe-Ser-Cys, the peptide derived from the beta chain of human Hb, was synthesized as an immunogen, and a monoclonal antibody against the peptide was prepared. A latex immunoassay method was established using the antibody on an automatic analyzer. In this study, 20 samples from healthy subjects and 80 samples from nondiabetic patients undergoing hemodialysis (HD) were analyzed. RESULTS: The latex immunoassay method using the antibody correlated significantly with the ELISA method using the antibody (r = 0.95; P <0.001). Between healthy subjects (n = 20) and nondiabetic HD patients (n = 80), a significant difference was seen in circulating CML-Hb (525 +/- 76 vs 778 +/- 137 pmol CML/mg of Hb; P <0.0001). CONCLUSION: The latex method for the CML-Hb site specific to Lys-66 on the beta chain can measure large numbers of samples on an automatic analyzer.

Acetaldehyde↗
PubMed2001

[A case of ovarian cancer with metastatic tumor in the liver with paclitaxel and carboplatin systemic chemotherapy was very effective].

An 82-year-old woman was admitted to the Dept. of Obstetrics and Gynecology, Yamanashi Medical University to try to identify the origin of a liver metastatic tumor. CT examination revealed a small tumor located adjacent to the uterine cervix in a cul-de-sac. With biopsy using MR, it was clearly shown histologically that the origin of the tumor was the ovary. Systemic chemotherapy with paclitaxel and carboplatin was selected as the most reasonable treatment for this case because of the patient's age. After 6 courses of this chemotherapy, the tumor in the cul-de-sac disappeared and the tumor in the liver decreased markedly. Furthermore, no severe side effects were seen during this treatment. This result indicated that systemic chemotherapy with paclitaxel and carboplatin is effective and safe in cases of advanced ovarian cancer.

Adenocarcinoma↗
PubMed2000

Testis developments and puberty in the male Tokara (Japanese native) goat.

In male Tokara (Japanese native) goats, testis development and the onset of puberty were studied histologically and observing sexual behaviour. Testes weight increased from 36+/-5.4 (S.E.) g (n=5) at 3 months of age to 126+/-6.3 g (n=6) at 12 months. The degree of the testis development differed among kids at 3 months of age and only one of four had produced spermatozoa in the testis. Large number of spermatozoa were always present in seminiferous tubules and epididymal ducts from 4 months of age. The diameter of seminiferous tubules increased from 133+/-9.9 microm (n=4) at 3 months to 198+/-1.0 microm (n=3) at 6 months with little increase thereafter. Mounting and pelvic thrusts onto a teaser doe started at from 9 to 14 weeks of age. Ejaculated semen contained sperm with good motility for the first time from 17 weeks. The male Tokara goat reaches puberty at around 4 months of age but testis development continues to 12 months.

Age Factors↗
PubMed2000

Impact of Helicobacter pylori infection on gastric cancer incidence in a general Japanese population: the Hisayama study.

BACKGROUND: Several nested case-control studies have reported the potentially causal relationship between Helicobacter pylori infection and the development of gastric cancer. However, there has been no prospective study evaluating this issue. The purpose of this study is to examine the impact of H pylori infection on gastric cancer occurrence in a general Japanese population (Hisayama, Japan) stratified according to sex, using a prospective study design. METHODS: A total of 2602 subjects aged 40 years or older (1070 men; mean age, 57 years; 1532 women; mean age, 59 years) without a history of gastrectomy or gastric cancer were classified according to the status of the serum IgG antibodies to H pylori and observed prospectively for 9 years from 1988. RESULTS: Infection of H pylori was more common in men (71.5%) than in women (62.5%; P<.001). The age-adjusted incidence of gastric cancer for men (5.3 per 1000 person-years) was 4-fold higher than that for women (1.3; P<.001). In men, the age-adjusted incidence of gastric cancer was significantly higher in the subjects with H pylori infection than in those without it (6.2 vs 2.5; relative risk, 2.59 [95% confidence interval, 1.03-6.50]), whereas no significant difference was observed in women (1.2 vs 1.1; relative risk, 0.99 [95% confidence interval, 0.36-2.68]). These results were similar even after controlling for other risk factors in multivariate analysis. It was estimated that 40.1% of gastric cancers for men in this cohort were attributable to H pylori infection. CONCLUSION: A significant relationship exists between infection with H pylori and subsequent occurrence of gastric cancer for men but not for women in this Japanese population.

Adult↗
PubMed2000

Selenoorganic compound, ebselen, inhibits nitric oxide and tumor necrosis factor-alpha production by the modulation of jun-N-terminal kinase and the NF-kappab signaling pathway in rat Kupffer cells.

In response to the bacterial endotoxin, LPS, Kupffer cells are induced to express NO and TNF-alpha. These compounds are involved in hepatic inflammation/injury, especially that associated with endotoxic shock. In this study, we demonstrate that ebselen (2-phenyl-1,2-benzisoselenazol-3[2H]one), a selenoorganic compound, blocks LPS-induced NO and TNF-alpha production by cultured rat liver Kupffer cells. LPS can activate both the NF-kappaB signaling pathway and MAPK signal transduction pathways such as JNK and p38 MAPK. We find that ebselen inhibits LPS-induced NF-kappaB nuclear translocalization, and also suppresses the LPS-induced phosphorylation of JNK, but not the phosphorylation of p38 MAPK. This inhibition of signal transduction leads to a decrease in the transcription of TNF-alpha and the inducible isoform of NO. Furthermore, ebselen inhibits LPS-induced COX-2 expression, which is responsible for proinflammatory prostaglandin production, without affecting constitutive COX-1 expression. These data suggest the mechanism by which ebselen acts as an antiinflammatory agent, and also suggest that ebselen may be potent in preventing hepatic injury such as endotoxic shock, in which Kupffer cell activation has been implicated.

Animals↗
PubMed2000

Experimental immune-mediated blepharoconjunctivitis in rats induced by immunization with ragweed pollen.

BACKGROUND: A study was performed to compare the effects of immunization with ragweed pollen (RW) in two different adjuvants on the characteristics of a previously described model of experimental immune-mediated blepharoconjunctivitis (EC) in rats. METHODS: Lewis or Brown Norway (BN) rats were immunized with 100 microg of RW in emulsion with aluminum hydroxide [Al(OH)3] or complete Freund's adjuvant (CFA). Three weeks later, the animals were challenged with eye drops containing RW in PBS. Twenty-four hours after topical challenge, eyes, blood, and lymph nodes were obtained for histology, measurement of antigen-specific antibodies, and proliferation or cytokine assays, respectively. In addition to active immunization, recipients of RW-primed lymph node cells were challenged and evaluated as above. RESULTS: RW in both adjuvants induced infiltration with predominantly mononuclear cells in Lewis rats and eosinophils in BN rats. As well as active immunization, eosinophils were detected only in BN rats by adoptive transfer of cells. Lymphocyte proliferative responses to RW were high in immunized Lewis rats when CFA was used as an adjuvant. In contrast, proliferative responses in BN rats were higher when Al(OH)3 was used. RW-specific IgE was detected only in BN rats. There were no significant differences in RW-specific IgG1/IgG2a ratio among the four groups. Lewis rats had higher level of RW-specific interferon-gamma in the culture supernatant. CONCLUSIONS: The characteristics of EC are different in Lewis and BN rats, dependent on the genetic background of the rat strains. The response to RW was similar to other previously used antigens, such as ovalbumin.

Allergens↗
PubMed2000

Time-resolved two-dimensional X-ray diffraction study of the effect of shortening on activation of contracting skeletal muscle.

In twitch contractions of frog skeletal muscle, the isometric tension peaks when intracellular calcium has fallen to near-resting levels. To understand the mechanism of this delayed tension maintenance in the context of calcium regulation, the time course of the tropomyosin movement on actin was monitored by recording the intensity of the 2nd actin layer lines in a time-resolved two-dimensional X-ray diffraction study. The intensity rose ahead of tension, reflecting the tropomyosin movement from its "off" to "on" positions, but it fell with a time course similar to that of tension. Muscle shortening applied at the tension peak was followed by a poor recovery of tension, and accelerated the fall of the reflection intensity. The results suggest that the force-generating myosin heads retain the tropomyosin in its "on" position after the fall of intracellular calcium, and their shortening-induced detachment makes the tropomyosin return to its "off" position, thereby preventing myosin reattachment to actin.

Animals↗
PubMed2000

Influence of ionic strength on the actomyosin reaction steps in contracting skeletal muscle fibers.

Muscle contraction occurs as the result of actin-myosin interaction, which is mediated by the intermolecular forces exerted at the actin-myosin interface. To obtain information about the nature of these intermolecular forces, we tested the sensitivity of various contractile parameters of skinned skeletal muscle fibers to ionic strength (IS) at 3-5 degrees C; IS variation is a useful technique for distinguishing between ionic and nonionic (primarily hydrophobic) types of intermolecular forces. The most striking effect of elevated IS was the strong suppression of isometric tension. However, none of the measured parameters suggested a corresponding decrease in the number of force-generating myosin heads on actin. The rate of actin-myosin association seemed to be only modestly IS-sensitive. The following force-generating isomerization was apparently IS-insensitive. The dissociation of the force-generating actomyosin complex was decelerated by elevated IS, contrary to the expectation from the suppressed isometric tension. These results led us to conclude that an IS-sensitive step, responsible for the large suppression of tension, occurs after force-generating isomerization but before dissociation. The present study suggests that the actomyosin interaction is generally nonionic in nature, but there are at least two ionic processes, one at the beginning and the other close to the end of the actomyosin interaction.

Actins↗
PubMed2000

Effect of caspase inhibitors on myocardial infarct size and myocyte DNA fragmentation in the ischemia-reperfused rat heart.

OBJECTIVE: Caspase family proteases are recognized as key mediators of apoptosis. However, the role of caspases in the ischemia-reperfused heart remains uncertain. We evaluated the effect of caspase inhibitors on myocardial infarct size and the myocyte DNA fragmentation in the ischemia-reperfused rat hearts. METHODS: Three groups of Sprague-Dawley rats (n = 7, each) were subjected to 30 min of ischemia followed by 6 h of reperfusion. One of the following drugs: (1) YVAD-aldehyde, a caspase-1-like protease inhibitor (3.5 mg/kg; YVAD), (2) DEVD-aldehyde, a caspase-3-like protease inhibitor (3.5 mg/kg, DEVD), (3) vehicle (140 microliters/kg) was administered intravenously 5 min prior to the ischemia in each group. Myocardial infarct size was defined by triphenyltetrazolium chloride (TTC) staining. Immunohistochemical staining by in situ nick end labeling (TUNEL) of cardiomyocytes and DNA electrophoresis were used for detecting DNA fragmentation. Ultrastructural analysis was done by electron microscopy. The caspase activity was measured in the myocardium of both groups. RESULTS: The percentage of TUNEL-positive myocyte nuclei (%AP) was quantified by microscopy. A ladder pattern was detected by electrophoresis of DNA from the risk area and TUNEL-positive myocytes were seen in the risk area. The %AP was significantly reduced from 20 +/- 1% to 12 +/- 3% by YVAD and to 10 +/- 3% by DEVD (both P < 0.01). However, caspase inhibitors did not significantly change the infarct size. Electronmicrograph showed similar salcolemmal and mitochondrial damage in both group. The caspase activity was blocked by DEVD at 4 h after reperfusion. CONCLUSION: Myocyte DNA fragmentation and caspase activation was inhibited by caspase inhibitors without reduction of the infarct size in ischemia-reperfused rat hearts.

Analysis of Variance↗
PubMed2000

A p160ROCK-specific inhibitor, Y-27632, attenuates rat hepatic stellate cell growth.

BACKGROUND/AIMS: p160ROCK, a serine/threonine protein kinase, is a direct RhoA target mediating RhoA-induced assembly of focal adhesions and stress fibers. Recently, Rho signaling pathways were reported to play an important role in the activation of rat hepatic stellate cells (HSC). The aim of this study was to investigate the mechanism of action of a p160ROCK-specific inhibitor, Y-27632, on cultured rat HSC. METHODS: HSC were isolated from normal rat livers and cultured on fibronectin-coated dishes. The cell morphology and actin cytoskeleton were studied with phase contrast and fluorescence microscopy, respectively. Immunoblot analysis was used to examine phosphorylation of focal adhesion kinase and extracellular signal-regulated kinase, and the expression of cell cycle-associated proteins. HSC proliferation was measured by quantitating the percentage of cells that exhibited nuclear incorporation of 5-bromodeoxyuridine. Type I collagen gene expression and accumulation in HSC culture media were evaluated by Northern blot and enzyme-linked immunosorbent assay, respectively. RESULTS: Y-27632 consistently blocked cell spreading and suppressed RhoA-induced formation of stress fibers in HSC. In addition, Y-27632 inhibited phosphorylation of focal adhesion kinase and extracellular signal-regulated kinase. Cells treated with Y-27632 failed to proliferate, in contrast to untreated spread cells. This shape-dependent block in cell proliferation correlated with a failure to increase cyclin D1 protein level and to down-regulate the cell cycle inhibitor p27. Y-27632 decreased type I collagen gene expression and accumulation in HSC culture media. CONCLUSIONS: Our findings indicate that p160ROCK-mediated actin stress fiber assembly is involved in the pathophysiology of hepatic fibrogenesis and suggest that inhibitors of the RhoA-ROCK pathway might be useful therapeutically in liver fibrogenesis.

Adipocytes↗
PubMed2000

Synthesis and resorption of a humoral chymotrypsin inhibitor, CI-8, by fat body of the silkworm, Bombyx mori.

The Bombyx mori hemolymph contains up to 16 chymotrypsin inhibitors (CIs). The present in vitro culture of tissues in Grace's medium indicated that CI-8, which belongs to the largest molecular-size group of CIs with sugar moiety, is synthesized in the fat body and secreted from it during the feeding period. When the fat body from other strain which synthesizes an allelic component (CI-7) instead of CI-8 was incubated in vitro in hemolymph from the strain which has CI-8, the fat body was found to receive CI-8. Thus it was concluded that CI-8, once secreted into the hemolymph, was again sequestered into the fat body after the onset of spinning. Protein granules isolated from the pupal fat body were shown to contain CI-8, indicating that the sequestered CI-8 is present in the protein granules.

Animals↗
PubMed2000

Platelet-derived growth factor receptor tyrosine kinase inhibitor AG1295 attenuates rat hepatic stellate cell growth.

Enhanced activity of receptor tyrosine kinases such as the platelet-derived growth factor-receptorbeta (PDGF-Rbeta) has been implicated as a contributing factor in the development of hepatic fibrosis. In this study we have used tyrosine kinase inhibitors of the tyrphostin class (AG1295) to specifically block autophosphorylation of PDGF-Rbeta and proliferation of rat hepatic stellate cells. We also examined the effect of AG1295 on the PDGF-BB-induced activation of the 44 kd and 42 kd mitogen-activated protein (MAP) kinase isoforms (p44mapk/p42mapk). Rat hepatic stellate cells were treated with AG1295 (10 micromol/L) for 24 hours and stimulated with PDGF-BB for 5 minutes. AG1295 specifically inhibited autophosphorylation of PDGF-Rbeta and caused a 20% decrease in PDGF-BB-stimulated bromodeoxyuridine incorporation by rat hepatic stellate cells. Treatment of rat hepatic stellate cells with AG1295 resulted in an inhibition of the PDGF-BB-induced activation of MAP kinase isoforms. Quantification of the immunoprecipitated tyrosine-phosphorylated phosphatidylinositol 3-kinase, phospholipase C-gamma, and p21ras guanosine triphosphatase-activating protein by Western blotting revealed that AG1295 treatment effectively inhibits tyrosine phosphorylation of these kinases in hepatic stellate cells. Our findings demonstrate that AG1295 is a selective inhibitor of the tyrosine phosphorylation of PDGF-Rbeta and its downstream signaling pathway, and this compound could offer a strategy for the treatment of fibrotic liver diseases.

Animals↗
PubMed2000

Atomic force microscopy in structural biology: from the subcellular to the submolecular.

Atomic force microscopy (AFM) is capable of generating images within ranges of resolution that are of particular interest in biology. Although atomic resolution may not be possible with biological samples, a great deal of information can still be obtained from images that provide structures at a slightly lower level of resolution. The submolecular resolution images of bacteriorhodopsin and the chaperonin GroES, which revealed, respectively, individual loops and beta-turns, confirmed and complemented other structural investigations, while the molecular-level features in images of membrane-bound VacA, a cytotoxin from Helicobacter pylori, immediately suggested the possibility, subsequently proven, of channel-forming ability. A series of images with macromolecular resolution directly provided details on the mechanisms by which RNA polymerase nonspecifically translocates along DNA, and images with subcellular resolving power of erythrocytic cellular membranes showed, with unambiguous clarity, linear arrays of molecular complexes. In this review, we will describe some of the most biologically relevant findings that have been obtained with AFM within ranges of resolution from the submolecular to the molecular, and from the macromolecular to the subcellular. Furthermore, we will describe some of the sample conditions and imaging environments that are likely important to achieve a particular level of resolution.

Bacterial Proteins↗