Biomedical subjects

Yukio Ishikawa

Publications and source records attributed to Yukio Ishikawa.

At least 19 recordsLinked to original sources

PubMed2007

Significance of lymphatic invasion on regional lymph node metastasis in early gastric cancer using LYVE-1 immunohistochemical analysis.

It has been reported that lymphatic invasion is a predictor for lymph node metastasis in early gastric cancer (EGC); however, it has been impossible to differentiate between lymphatic invasion and blood vessel invasion using current staining techniques. We studied the significance of lymphatic invasion on regional lymph node metastasis in EGC by using human lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) antibody, specific to lymphatic vessels, and von Willebrand factor (vWF) antibody, specific to the blood vessels, to clearly distinguish these vascular tissues.EGC tissues were obtained from 66 node-positive and 66 node-negative subjects and were matched by age and sex. These tissues were immunostained with antibodies against LYVE-1 and vWF. Multivariate logistic regression analysis demonstrated that lymphatic invasion was a significant independent predictor for regional lymph node metastasis (odds ratio, 4.667; P = .0094), whereas blood vessel invasion was not. Thus, lymphatic invasion identified by LYVE-1 antibody could predict the existence of regional lymph node metastasis in EGC.

Biomarkers, Tumor↗

PubMed2006

Cloning and characterization of the HSP70 Gene, and its expression in response to diapauses and thermal stress in the onion maggot, Delia antiqua.

The cytosolic members of the HSP70 family of proteins play key roles in the molecular chaperone machinery of the cell. In the study we cloned and sequenced the fulllength cDNA of Delia antiqua HSP70 gene, which is 2461 bp long and encodes 643 a.a. with a calculated molecular mass of 70,787 Da. We investigated gene copies of cytosolic HSP70 members of 4 insect species with complete genome available, and found that they are quite variable with species. In order to characterize this protein we carried out an alignment and a phylogenetic analysis with 41 complete protein sequences from insects. The analysis divided the cytosolic members of the family into two classes, HSP70 and HSC70, distinguishable on the basis of 15 residues. HSP70 class members were slightly shorter in length and smaller in molecular mass relative to the HSC70 class members, and the conservative and functional regions in these sequences were documented. Mainly, we investigated the expression of Delia antiqua HSP70 gene, in response to diapauses and thermal stresses. Both summer and winter diapauses elevated HSP70 transcript levels. Cold-stress led to increased HSP70 expression levels in summer- and winter-diapausing pupae, but heat-stress elevated the levels only in the winter-diapausing pupae. In all cases, the expression levels, after being elevated, gradually decreased with time. HSP70 expression was low in non-diapausing pupae but was up-regulated following cold- and heatstresses. Heat-stress gradually increased the mRNA level with time whereas cold-stress gradually decreased levels after an initial increase.

Amino Acid Sequence↗

PubMed2006

Detection of myocardial bridge and evaluation of its anatomical properties by coronary multislice spiral computed tomography.

BACKGROUND: Myocardial bridge (MB) is a common anatomical condition, under which a part of the coronary artery running in the epicardial adipose tissue, is covered with myocardial tissue. It regulates atherosclerosis development and sometimes evokes coronary heart disease through haemodynamic alterations. We attempted to efficiently detect MB and evaluate the anatomical properties of MB by coronary multislice spiral computed tomography (MSCT). METHODS: Sixteen-row MSCT was conducted on 148 patients with coronary heart disease. MSCT images were reconstructed and reformed with transverse scans, curved planar reformat and three-dimensional volume-rendered images. The MB, over 1.0 mm in thickness, was identified by the presence of the "step-down and step-up" appearance. After "trial and error" essays, we could consistently examine the frequency of MB and evaluate the anatomical properties of MB, especially its thickness, together with coronary wall lesions. RESULTS: Twenty-three patients (15.8%) had MB over 1.0 mm in thickness: 21 MBs (87.5%) were located in the left anterior descending artery with a mean thickness and length of 1.8+/-0.7 and 20.0+/-8.6 mm. Moreover, although the tunneled segment beneath MB was always free of coronary wall lesions, 79.2% (19/24) of the segments proximal to MB demonstrated coronary wall lesions. Of special significance were three symptomatic MB patients without any atherosclerotic lesion throughout all the coronary arteries. CONCLUSION: Coronary MSCT is a new imaging technique that provides a non-invasive diagnostic tool for MB and yields much better results of MB detection than previous imaging methods.

Abnormalities, Multiple↗

PubMed2006

Transgenic expression of group V, but not group X, secreted phospholipase A2 in mice leads to neonatal lethality because of lung dysfunction.

In an effort to elucidate the functions of secreted phospholipase A2 (sPLA2) enzymes in vivo, we generated transgenic (Tg) mice for group V sPLA2 (sPLA2-V) and group X sPLA2 (sPLA2-X), which act potently on phosphatidylcholine in vitro. We found that sPLA2-V Tg mice died in the neonatal period because of respiratory failure. The lungs of sPLA2-V Tg mice exhibited atelectasis with thickened alveolar walls and narrow air spaces, accompanied by infiltration of macrophages and only modest changes in eicosanoid levels. This severe pulmonary defect in sPLA2-V Tg mice was attributable to marked reduction of the lung surfactant phospholipids, phosphatidylcholine and phosphatidylglycerol. Given that the expression of sPLA2-V is greatly elevated in human lungs with severe inflammation, our present results raise the intriguing possibility that this isozyme may contribute to ongoing surfactant hydrolysis often observed in the lungs of patients with respiratory distress syndrome. In contrast, sPLA2-X Tg neonates displayed minimal abnormality of the respiratory tract with normal alveolar architecture and surfactant composition. This unexpected result was likely because sPLA2-X protein existed as an inactive zymogen in most tissues. The active form of sPLA2-X was detected in tissues with inflammatory granulation in sPLA2-X Tg mice. These results suggest that sPLA2-X mostly remains inactive under physiological conditions and that its proteolytic activation occurs during inflammation or other as yet unidentified circumstances in vivo.

Animals↗

PubMed2006

Leaf epicuticular wax chemicals of the Japanese knotweed Fallopia japonica as oviposition stimulants for Ostrinia latipennis.

Extraction, fractionation, and gas chromatography-mass spectrometry analyses guided by bioassays have shown that n-alkanes and free fatty acids in leaf epicuticular wax of the Japanese knotweed Fallopia (Reynoutria) japonica stimulate oviposition in the Far-Eastern knotweed borer, Ostrinia latipennis (Lepidoptera: Crambidae). n-Alkanes made up 48.1% of the total amount of epicuticular wax, and their carbon chain length was in the C(16)-C(33) range, with n-nonacosane (n-C(29)) most abundant, followed by n-C(27), n-C(25), and n-C(31). Free fatty acids with C(9)-C(22) accounted for 22.3%, and hexadecanoic acid was predominant. A mixture of authentic n-alkanes and fatty acids of the composition found in the epicuticular wax, a mixture of n-alkanes, and a mixture of fatty acids significantly enhanced oviposition. Thus, it was demonstrated that both n-alkanes and free fatty acids in leaf epicuticular wax of F. japonica are naturally occurring oviposition stimulants for O. latipennis.

Alkanes↗

PubMed2006

Ultrasonic courtship song in the Asian corn borer moth, Ostrinia furnacalis.

Although sex pheromone communication in the genus Ostrinia (Lepidoptera: Crambidae) has been studied intensively, acoustic communication in this genus has not been explored. In this study, we report that male-produced ultrasound serves as a courtship song in the Asian corn borer moth, O. furnacalis. Upon landing close to a pheromone-releasing female, a male showed a series of courtship behaviors involving emission of ultrasound. The sounds were produced when the wings were vibrated quickly in an upright position. The male song was composed of chirps, i.e., groups of pulses (duration of a chirp = 58.9 ms, 8.8 pulses/chirp), with a broadband frequency of 25-100 kHz. In flight tunnel experiments, deaf and hearing females showed a significant difference in the incidence of three behavioral responses to courting males, i.e., immediate acceptance, acceptance after walking, and rejection. Deaf females showed more 'rejection' and less 'acceptance after walking' than hearing females, indicating that the detection of male-produced ultrasound plays an important role in the acceptance of a male. The findings are discussed in the context of exploitation of receiver bias and mate choice.

Animals↗

PubMed2006

Small GTPase Rnd1 is involved in neuronal activity-dependent dendritic development in hippocampal neurons.

Rho family small GTPases are key regulators for neuronal morphogenesis including dendritogenesis. We recently have shown that Rnd1, a member of the Rho family, is highly expressed in brain during the synaptogenic stage and is involved in dendritic spine formation. However, the mechanism by which Rnd1 regulates dendritic development including spine morphogenesis remains unknown. Here we report that Rnd1, a member of the Rho family, plays a critical role in neuronal activity-dependent dendritic development in hippocampal neurons. Overexpression of Rnd1 promoted dendritic growth and branching in cultured hippocampal neurons. On the other hand, suppression of endogenous Rnd1 expression by RNA interference significantly inhibited neuronal activity-dependent dendritic development and this inhibitory effect was canceled by inhibition of RhoA effector ROCK. In addition, knockdown of Rnd1 also abolished dendritic development promoted by treatment with brain-derived neurotrophic factor in hippocampal neurons. Our findings demonstrate that Rnd1 is involved in signaling pathways of neuronal activity-dependent dendritic development.

Action Potentials↗

PubMed2006

Differential distribution of ELMO1 and ELMO2 mRNAs in the developing mouse brain.

ELMO is an upstream regulator of the Rho family small GTPase Rac. We investigated the distributions of mRNAs of two subtypes of ELMO, ELMO1 and ELMO2, in the developing mouse brain. Both ELMO1 and ELMO2 mRNAs are widely distributed in the developing mouse brain, but they were expressed in different neuronal populations in the cerebral cortex, thalamus, and cerebellum. Thus, ELMO1 and ELMO2 may play different roles during brain development.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Myocardial apoptosis associated with the expression of proinflammatory cytokines during the course of myocardial infarction.

To clarify the role of myocardial apoptosis associated with the expression of proinflammatory cytokines in human myocardial infarction (MI), we have analyzed the expression of apoptosis positive for single-stranded DNA (ss-DNA) antibody, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-8 in 147 samples of infarcted myocardial tissue from 65 patients. ss-DNA-positive apoptotic nuclei were found mainly in cardiomyocytes in the border zones and granulation tissue cells in the infarct foci. The ss-DNA index (SI) of cardiomyocytes (average 0.13%) peaked at stage II (established myocardial necrosis), the value being significantly higher than at stages III (macrophage infiltration), IV (granulation formation), and V (scar formation) (P<0.05), whereas the SI of granulation tissue (average 0.08%) at stages III, IV, and V showed no significant differences between the three stages. These results suggest that cardiomyocyte apoptosis in the border zone is responsible for cellular loss in the acute stage of MI, whereas granulation tissue apoptosis may not be involved in the process of ventricular remodeling. TNF-alpha was expressed in cardiomyocytes in the border zones of infarct foci, but no significant positive correlation was found between SI and TNF-alpha index in cardiomyocytes (r=0.08, P = 0.37), suggesting that TNF-alpha does not serve as a direct trigger of cardiomyocyte apoptosis in vivo. The number of IL-8-positive cells peaked at stage II, and IL-8-myeloperoxidase-double-positive neutrophils were frequently detected, indicating that infiltrating neutrophils are the predominant source of IL-8 in the infarcted myocardium. These results suggest that, in human MI, TNF-alpha produced by cardiomyocytes does not play a critical role in their apoptosis, and that IL-8 produced by neutrophils is responsible for the subsequent accumulation and activation of neutrophils, thus increasing the degree of myocardial damage.

Aged↗

PubMed2006

Unusual response characteristics of pheromone-specific olfactory receptor neurons in the Asian corn borer moth, Ostrinia furnacalis.

Male moth pheromone-detecting receptor neurons are known to be highly specific and very sensitive. We investigated physiological and behavioral responses to female sex pheromone components in male Ostrinia furnacalis moths (Lepidoptera: Crambidae). Using recordings from a cut-sensillum technique, trichoid sensilla could be grouped into four physiological types (1-4), according to the response of receptor neurons to the two major pheromone components, (E)-12- and (Z)-12-tetradecenyl acetate (E12- and Z12-14:OAc). These types could subsequently be characterized as four subtypes (A-D) depending on neural responses to pheromone components from various sister species of O. furnacalis, (Z)-9-, (E)-11- and (Z)-11-tetradecenyl acetate. The peripheral pheromone detection system of O. furnacalis is different to that of other moths. A large majority of the neurons investigated responded to both of the two principal pheromone components. Dose-response and cross-adaptation studies showed that olfactory receptor neurons with large amplitude action potentials responded equally well to E12- and Z12-14:OAc in sensillum types 1-3. Field experiments showed that O. furnacalis males are sensitive to ratios of E12- and Z12-14:OAc and that (Z)-9-tetradecenyl acetate acts as a behavioral antagonist. O. furnacalis males thus display an unusual coding system for odors involved in sexual communication, mainly built on less specific neurons, but still have the ability to detect and respond to the correct female blend. We hypothesize that the pheromone detection system of O. furnacalis consists of two parts, where one is devoted to high sensitivity to Delta12 isomers of tetradecenyl acetate, E12- and Z12-14:OAc and the other to highly specific responses to the E12- or Z12-14:OAc. The unusual feature is thus that a large part of the system is devoted to sensitivity and only a minor part to selectivity. This could be explained by the fact that no other moth species are known to use E12- and/or Z12-14:OAc and that no strong selective pressure to increase selectivity between the isomers has been determined.

Action Potentials↗

PubMed2006

Comparison of larvicidal, adulticidal and acaricidal activity of two geometrical butylidenephthalide isomers.

Insecticidal and acaricidal activities of two geometrical isomers, (E)- and (Z)-butylidenephthalide isolated from Angelica acutiloba, against larvae and adults of fruit fly (Drosophila melanogaster), cat fleas (Ctenocephalides felis) and house dust mites (Dermatophagoides farinae and Tyrophagus putrescentiae) were investigated and compared with that of positive controls. (E)- and (Z)-Butylidenephthalide exhibited 50% lethal concentration (LC50) values of 2.07 and 0.94 micromol/ml of diet concentration against larvae of D. melanogaster, respectively. This indicated that two isomers of butylidenephthalide have geometrical stereoselectivity for larvicidal effect. Even though both (E)- and (Z)-butylidenephthalide also showed potent adulticidal and acaricidal activity against adults of D. melanogaster and two mites, there was no significant difference between two isomers. Insecticidal activity of both (E)- and (Z)-butylidenephthalide toward adults of C. felis was not detected even at the maximum concentration of 200 microg/cm2.

Aging↗

PubMed2005

cDNA cloning and in situ hybridization of Delta11-desaturase, a key enzyme of pheromone biosynthesis in Ostrinia scapulalis (Lepidoptera: Crambidae).

Female sex pheromones are considered to be produced in a "pheromone gland" located in the terminal abdominal segments (8th-10th, TAS) of a moth; however, in many moth species, the cells that produce pheromones have not actually been specified. We investigated cells in the TAS that synthesize pheromones in the adzuki bean borer Ostrinia scapulalis, by locating pheromones and their precursors, and mRNA for Delta11-desaturase, a key enzyme in pheromone biosynthesis. We demonstrated that the pheromone components, (E)-11- and (Z)-11-tetradecenyl acetates, and their fatty acyl precursors were specifically contained in the dorsal part of the TAS. A cDNA (OscaZ/E11) that encodes a Delta11-desaturase was cloned from the TAS. RT-PCR and in situ hybridization unequivocally showed that OscaZ/E11 is specifically expressed in the modified epidermal cells located at the dorsal end of the 8th-9th intersegmental membrane.

Amino Acid Sequence↗

PubMed2005

Diverse cellular localizations of secretory phospholipase A2 enzymes in several human tissues.

The secretory phospholipase A2 (sPLA2) family in mammals contains more than 10 enzymes. In this study, we examined by immunohistochemistry the localization of six sPLA2s (IIA, IID, IIE, IIF, V and X) in human heart, kidney, liver and stomach. In normal hearts, sPLA2-IIA was detected in coronary vascular smooth muscle cells (VSMC) and sPLA2-V in cardiomyocytes beneath the endocardium. In infarcted hearts, expression of these two enzymes was markedly increased in damaged cardiomyocytes, and expression of sPLA2-IID and-IIE, which was undetectable in normal hearts, was elevated in damaged cardiomyocytes and VSMC, respectively. In infarcted kidneys, sPLA2-IIA and-V were markedly induced in the uriniferous tubular epithelium. In livers affected by viral hepatitis, sPLA2-IIA and-V were expressed in hepatocytes with fatty degeneration. In the gastric glands exhibiting intestinal metaplasia, sPLA2-IIA was localized in the glandular base, sPLA2-IID and-V in the glandular body epithelium, sPLA2-IIE and-IIF in goblet cells in the foveolar epithelium, and sPLA2-X in both glandular body epithelial cells and foveolar epithelial goblet cells. In the gastric submucosal tissues, sPLA2-IIA and-IIE were located in VSMC and sPLA2-V was in the interstitial fibroblasts. In addition, sPLA2-IIA,-IIE,-IIF and-X were highly expressed in gastric signet ring cell carcinoma. Thus, individual sPLA2s exhibit unique cellular localizations in each tissue, suggesting their distinct roles in pathophysiology.

Aged↗

PubMed2005

Significance of anatomical properties of myocardial bridge on atherosclerosis evolution in the left anterior descending coronary artery.

Myocardial bridge (MB) is frequently detected in the left anterior descending coronary artery (LAD), and LAD intima under MB is significantly spared from atherosclerotic evolution. Significance of anatomical features of MB on the extent of atherosclerosis of LAD was histomorphometrically investigated. Full-length 200 LADs with MB and 100 control LADs without MB were cross-sectioned at 5 mm intervals, and atherosclerosis ratio and intimal lesion types were evaluated. In cases with MB located within 5 cm from the left coronary ostium, atherosclerosis ratio in the proximal part of LAD was significantly lower than in control group, but, in cases with MB locating more than 5 cm from the ostium, atherosclerosis ratio in this part was similar to that in control cases. MB thickness was significantly correlated with its length, and the longer the MB the more proximally it tended to be located in LAD. Atherosclerosis ratio under MB was lower in cases with thick or long MBs than in cases with thinner or shorter MBs. In addition, intimal lesion in segments proximal to MB tended to be eccentric. Our results suggest that these anatomical properties of MB are the critical modulators for atherosclerosis evolution in the entire course of LAD.

Aged↗

PubMed2005

Endocrine changes associated with the starvation-induced premature metamorphosis in the yellow-spotted longicorn beetle, Psacothea hilaris.

Under 25 degrees C and a long day photoperiod, about half of the fourth instar Psacothea hilaris larvae molt to the fifth instar on day 13 and pupate about 18 days later; the rest pupate without a further larval molt with a mean fourth instar period of 24 days. However, starvation of fourth instar larvae exceeding a threshold weight induces premature pupation, resulting in the formation of small but morphologically normal adults. To clarify the endocrine basis for this premature pupation, hemolymph juvenile hormone (JH) and ecdysteroid titers were quantified during the fed and the starved periods. Normally fed fourth instar larvae exhibited two populations with regard to JH and ecdysteroid titers, one having JH titers ranging from 1.2 to 2.1 ng/ml through to day 13, the other, similarly high titers in the early part of the instar but low titers reaching 0.1 ng/ml on day 13. One population had ecdysteroid titers with a peak of 43 ng/ml on day 10, coinciding well with the period when some larvae normally molt to the fifth instar (day 13), the other, a small peak of 14 ng/ml on day 14 and a large peak of 70 ng/ml on day 17 coinciding well with the period just before the prepupa stage. When fourth instar larvae were starved after 4 days of feeding, JH titers decreased sharply in the next 24h and never recovered, and a small but significant increase (to 21 ng/ml) in ecdysteroid titers was observed on day 6, followed by a large peak of 63 ng/ml on day 11. Altogether, these results suggest that starvation induces a rapid decline in the JH titer, and this cues the early occurrence of a small ecdysteroid peak that commits larvae to early metamorphosis.

Animals↗

PubMed2005

Larvicidal and adulticidal activity of alkylphthalide derivatives from rhizome of Cnidium officinale against Drosophila melanogaster.

The insecticidal activity of the chloroform extract of Cnidium officinale rhizomes and its constituents was investigated against larvae and adults of Drosophila melanogaster and compared with that of rotenone. Bioassay-guided isolation of the chloroform extract of C. officinale resulted in the isolation and characterization of four alkylphthalides, cnidilide (1), (Z)-ligustilide (2), (3S)-butylphthalide (3), and neocnidilide (4). The structures of these compounds were established by spectroscopic analysis. The isolated compounds 2, 3, and 4 exhibited LC50 values of 2.54, 4.99, and 9.90 micromol/mL of diet concentration against larvae of D. melanogaster, respectively. Against both sexes (males/females, 1:1) of adults (5-7 days old), compound 3 showed the most potent activity of the compounds isolated with the LD50 value of 5.93 microg/adult, comparable to that of rotenone (LD50 = 3.68 microg/adult). Structure-activity relationships of phthalides isolated suggest that the presence of conjugation with the carbonyl group in the lactone ring appeared to play an important role in the larvicidal activity. Acetylcholinesterase (prepared from the adult heads of D. melanogaster) inhibitory activity was also investigated in vitro to determine the insecticide mode of action for the acute adulticidal activity.

Alkylation↗

PubMed2005

Feeding glucose or sucrose, but not trehalose, suppresses the starvation-induced premature pupation in the yellow-spotted longicorn beetle, Psacothea hilaris.

Under 25 degrees C and a long-day photoperiod, starvation induces premature pupation in 4th instar Psacothea hilaris larvae exceeding a threshold weight of 180 mg, resulting in the formation of small but morphologically normal adults. To investigate possible mechanisms underlying this phenomenon, we first measured the hemolymph trehalose and glucose levels of starved larvae. When larvae were starved after 4 days of feeding (attaining the threshold weight), glucose levels decreased 4-fold within the next 24 h, while trehalose levels, after a temporary slight decrease, increased remarkably to reach a peak just before the prepupa stage. The effects of ingesting various nutrients on the developmental fate and the hemolymph sugar titers of starving larvae were then examined. Feeding on agar blocks containing sucrose or glucose totally suppressed the occurrence of premature pupation, while trehalose, fructose, casein and starch were ineffective. Feeding on glucose or trehalose resulted in a 6-fold decrease in hemolymph glucose levels and remarkably elevated trehalose levels. Since feeding on glucose and trehalose induced similar changes in hemolymph sugar titers but trehalose was not effective in suppressing premature pupation, glucose may have exhibited its effects via gustatory mechanisms.

Animal Nutritional Physiological Phenomena↗

PubMed2005

Cellular distribution, post-translational modification, and tumorigenic potential of human group III secreted phospholipase A(2).

Human group III secreted phospholipase A(2) (sPLA(2)-III) consists of a central group III sPLA(2) domain flanked by unique N- and C-terminal domains. We found that the sPLA(2) domain alone was sufficient for its catalytic activity and for its prostaglandin E(2) (PGE(2))-generating functions in various cell types. In several if not all cell types, the N- and C-terminal domains of sPLA(2)-III were proteolytically removed, leading to the production of the form containing only the sPLA(2) domain, which could be further N-glycosylated at two consensus sites. Immunohistochemistry demonstrated that sPLA(2)-III was preferentially expressed in the microvascular endothelium in human tissues with inflammation, ischemic injury, and cancer. In support of this, sPLA(2)-III was induced in cultured microvascular endothelial cells after stimulation with proinflammatory cytokines. Expression of sPLA(2)-III was also associated with various tumor cells, and colorectal cancer cells transfected with sPLA(2)-III exhibited enhanced PGE(2) production and cell proliferation, which required sPLA(2)-III catalytic activity. When implanted into nude mice, the sPLA(2)-III-transfected cells formed larger solid tumors with increased angiogenesis compared with control cells. Moreover, small interfering RNA for sPLA(2)-III significantly reduced PGE(2) production and proliferation of colorectal cancer cells. Taken together, these results reveal unique cell type-specific processing and N-glycosylation of sPLA(2)-III and the potential role of this enzyme in cancer development by stimulating tumor cell growth and angiogenesis.

Adenoviridae↗