Presence of the heme-oxo intermediate in oxygenation of carbon monoxide by cytochrome c oxidase revealed by resonance Raman spectroscopy.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
S Yoshikawa
Publications and source records attributed to S Yoshikawa.
2-Alkynyl-8-aryl-9-methyladenines as novel adenosine receptor antagonists: their synthesis and structure-activity relationships toward hepatic glucose production induced via agonism of the A(2B) receptor.
Novel adenosine antagonists, 2-alkynyl-8-aryl-9-methyladenine derivatives, were synthesized as candidate hypoglycemic agents. These analogues were evaluated for inhibitory activity on N-ethylcarboxamidoadenosine (NECA)-induced glucose production in primary cultured rat hepatocytes. In general, aromatic moieties at the 8-position and alkynyl groups at the 2-position had significantly increased activity compared to unsubstituted compounds. The preferred substituents at the 8-position of adenine were the 2-furyl and 3-fluorophenyl groups. In modifying the alkynyl side chain, change of the ring size, cleavage of the ring, and removal of the hydroxyl group were well tolerated. The order of the stimulatory effects of adenosine agonists on rat hepatocytes was NECA > CPA > CGS21680, which is consistent with involvement of the A(2B) receptor. In Chinese hamster ovary cells stably transfected with human A(2B) receptor cDNA, one of the compounds potent in hepatocytes, 15o (IC(50) = 0.42 microM), antagonized NECA-induced stimulation of cyclic AMP production (IC(50) = 0.063 microM). This inhibitory effect was much more potent than those of FK453, KF17837, and L249313 which have been reported to be respectively A(1), A(2A), and A(3) selective antagonists. These findings agree very well with the result that, compared to 15o, these selective antagonists for each receptor subtype showed only marginal effects in rat hepatocytes. These results suggest that adenosine agonist-induced glucose production in rat hepatocytes is mediated through the A(2B) receptor. Furthermore, 15o showed hypoglycemic activity in an animal model of noninsulin-dependent diabetes mellitus, the KK-A(y) mice. It is possible that inhibition of hepatic glucose production via the A(2B) receptor could be at least one of the mechanisms by which 15o exerts its in vivo effects. Further elaboration of this group of compounds may afford novel antidiabetic agents.
Adenine↗
The derailed guidance receptor does not require kinase activity in vivo.
The Drosophila Derailed (DRL) receptor tyrosine kinase (RTK) controls key guidance events in the developing nervous system and mesoderm. Like other members of the "related to tyrosine kinases" (RYK) subfamily of RTKs, DRL has several highly unusual amino acid substitutions within the catalytic domain, raising the possibility that members of this subfamily are catalytically inactive. To test the role of DRL kinase activity in vivo, we mutated the invariant lysine required for catalytic activity of known kinases and examined the ability of this mutant to function in two assays: a dominant gain-of-function axon switch assay in the nervous system and phenotypic rescue of muscle attachment in drl mutants. We show that this predicted kinase-deficient DRL mutant is capable of functioning in both assays. Our results indicate that DRL does not require kinase activity in vivo and suggest that members of the RYK subfamily of RTKs transduce signals unconventionally.
Animals↗
Kinetics of cytokines and PMN-E in thoracoscopic esophagectomy.
BACKGROUND: Perioperative increases in the levels of cytokines and polymorphonuclear leukocyte elastase (PMN-E) have been shown to be related to degree of surgical trauma. METHODS: We measured the changes in levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and PMN-E in the perioperative period in patients undergoing thoracoscopic esophagectomy (n = 15) and conventional transthoracic esophagectomy (n = 15) for thoracic esophageal cancer. RESULTS: Both IL-6 and IL-8 increased markedly immediately after transthoracic esophagectomy and thereafter, but only a slight increase was observed after the thoracoscopic procedure (IL-6: p = 0.047; IL-8: p = 0.03). A difference was also seen in the pattern of changes in PMN-E. Levels of PMN-E increased immediately after transthoracic esophagectomy and continued to be high up to the 3rd postoperative day, but they remained low after the thoracoscopic procedure and showed no increase (p <lt; 0.01). CONCLUSION: These results suggest that, compared with transthoracic esophagectomy, thoracoscopic esophagectomy results in less production of cytokines and PMN-E and thus causes less surgical trauma.
Cytokines↗
Attractiveness of facial averageness and symmetry in non-western cultures: in search of biologically based standards of beauty.
Averageness and symmetry are attractive in Western faces and are good candidates for biologically based standards of beauty. A hallmark of such standards is that they are shared across cultures. We examined whether facial averageness and symmetry are attractive in non-Western cultures. Increasing the averageness of individual faces, by warping those faces towards an averaged composite of the same race and sex, increased the attractiveness of both Chinese (experiment 1) and Japanese (experiment 2) faces, for Chinese and Japanese participants, respectively. Decreasing averageness by moving the faces away from an average shape decreased attractiveness. We also manipulated the symmetry of Japanese faces by blending each original face with its mirror image to create perfectly symmetric versions. Japanese raters preferred the perfectly symmetric versions to the original faces (experiment 2). These findings show that preferences for facial averageness and symmetry are not restricted to Western cultures, consistent with the view that they are biologically based. Interestingly, it made little difference whether averageness was manipulated by using own-race or other-race averaged composites and there was no preference for own-race averaged composites over other-race or mixed-race composites (experiment 1). We discuss the implications of these results for understanding what makes average faces attractive. We also discuss some limitations of our studies, and consider other lines of converging evidence that may help determine whether preferences for average and symmetric faces are biologically based.
Adolescent↗
Dynamic properties influence the perception of facial expressions.
Two experiments were conducted to investigate the role played by dynamic information in identifying facial expressions of emotion. Dynamic expression sequences were created by generating and displaying morph sequences which changed the face from neutral to a peak expression in different numbers of intervening intermediate stages, to create fast (6 frames), medium (26 frames), and slow (101 frames) sequences. In experiment 1, participants were asked to describe what the person shown in each sequence was feeling. Sadness was more accurately identified when slow sequences were shown. Happiness, and to some extent surprise, was better from faster sequences, while anger was most accurately detected from the sequences of medium pace. In experiment 2 we used an intensity-rating task and static images as well as dynamic ones to examine whether effects were due to total time of the displays or to the speed of sequence. Accuracies of expression judgments were derived from the rated intensities and the results were similar to those of experiment 1 for angry and sad expressions (surprised and happy were close to ceiling). Moreover, the effect of display time was found only for dynamic expressions and not for static ones, suggesting that it was speed, not time, which was responsible for these effects. These results suggest that representations of basic expressions of emotion encode information about dynamic as well as static properties.
Adolescent↗
Reduction methods of the reconstruction error for large-scale implementation of near-field acoustical holography.
New extrapolation methods in real and wave number spaces are proposed to extend near-field acoustical holography (NAH) toward a more quantitative technique applicable to the vibration measurement of actual large-scale structures. The finiteness of the measurement aperture is a serious impediment to such large-scale implementation of NAH because the measurement aperture sufficiently larger than the vibrating structure of interest is usually needed. We should thus investigate how to reduce the reconstruction error when the measurement aperture is restricted to a fraction of the vibrating structure. The following practical suggestions are derived from simulations and underwater experiments: (1) A wave number-space extrapolation method can reduce the reconstruction error to about 25% for the measurement aperture corresponding to 1/16th of the vibrating structure when 10,000 iterations of the extrapolation process are applied. (2) A real-space extrapolation method can reduce the reconstruction error to negligible degree (10(-10)%) for the measurement aperture corresponding to four times as large as the vibration structure when ten iterations of the extrapolation process are applied. (3) The former method may be widely and safely applied, but many iterations are necessary; the latter method can reduce the reconstruction error very quickly, but a wider measurement aperture than that in the former is needed. Therefore, when the measurement aperture cannot be larger than the vibrating structure, the former method is recommended, while when the measurement aperture is larger than the structure, the latter method is recommended. Summing up, the accuracy of our proposed methods, which is attributed to the property of data extrapolation method that the data inside the measurement aperture is conserved after adequately extrapolating the data outside the aperture, will be relevant to a more quantitative measurement and analysis of real large-scale structures.
Journal Article↗
Modification of thermosensitivity and chemosensitivity induced by combined treatments with hyperthermia and adriamycin.
Both adriamycin (ADM) and hyperthermia show thermal chemo-enhancement. Tolerance induction against ADM in heated cells has been reported resulting in clinical difficulty of cancer therapy. We investigated thermo-enhancement induced with ADM (0.2 microg/ml) treatment alone or combined with ADM and 42 degrees C hyperthermia in Chinese hamster V79 cells in vitro. Intracellular accumulation of hsc70 and hsp72 proteins after hyperthermia or ADM was observed to examine the possible relationship between cell killing effect and their accumulations. Thermosensitivity of V79 cells at 42 degrees C after the simultaneous treatments with ADM showed marked thermo-enhancement within the short-term treatments for less than 1 h, while the combined treatments for longer than 1 h, the cells showed reduced thermosensitivity. Survival from the simultaneous treatments for less than 1 h was reduced markedly less than the single treatment both with ADM or 42 degrees C hyperthermia alone. Thermotolerance was markedly induced in a step-up hyperthermia (42 degrees C 2 h-44 degrees C). The combined treatments with ADM and 44 degrees C hyperthermia following the 42 degrees C preheating alone does not inhibit thermotolerance development. The combined treatments with ADM and 42 degrees C preheating showed markedly interactive cell killing, but no thermo-enhancement to the following 44 degrees C hyperthermia was shown. The leveling slope of the 44 degrees C heating period-survival curve was drawn. In the Western blot analyses, hsc70 existed constitutively in the V79 cells. Following the 42 or 44 degrees C hyperthermia alone, intracellular accumulation of hsp72 was determined. ADM treatment alone did not induce any accumulation of hsp72. In the simultaneous treatments with ADM and hyperthermia, the accumulation of hsp72 was markedly reduced. The accumulation of hsp72 after the combined treatment with ADM and hyperthermia was not observed as markedly as that after hyperthermia alone.
Adaptation, Physiological↗
[The comparison between mental image manipulation and distinctive feature scan on recognition memory of faces].
The authors proposed "mental image manipulation of expression" as processing strategy for faces, and investigated whether this strategy facilitates memory for faces or not. In the Experiment, four groups of subjects were assigned to a combination of a task (mental image manipulation of expression or distinctive feature scan) and a retention interval (short-term latency or long-term latency). Each task was followed by an unexpected yes-no recognition test in which identical pictures of the target faces or the same person's expression-changed faces were randomly presented with distractor faces. The mental image manipulation group was better than distinctive feature scan group in long-term storage. This result is considered as a long-term effect of imagery encoding and a configurational encoding by mental image manipulation.
Adolescent↗
[Three-dimensional CT angiography of the hepatic artery with multislice CT: differences in image quality according to scanning pitch].
Three-dimensional CT angiography was reconstructed from the hepatic artery using multislice CT, and the effect of pitch during scanning on the quality of obtained images was examined. We randomly divided patients into two groups, with images of one group scanned at helical pitch 3 and images of the other at helical pitch 5.5. CT angiography was reconstructed by a volume-rendering technique. Evaluation was done visually, taking the sharpness of images of branches of the hepatic artery as a measure. Three-dimensional imaging scanned at pitch 3 tended to be better than that scanned at pitch 5.5.
Adult↗
Hormonal control of mRNA expression of immunoglobulin binding factor in uterine cervix.
Uterine cervical mucus contains an immunoglobulin binding factor (IgBF). It may play a role in preventing antibody production against sperm in the female reproductive tract. To elucidate the mechanism involved in the production of activated IgBF, we determined the effects of hormones on the expression of mRNAs of IgBF and of protein disulfide isomerase (PDI), activating enzyme, in uterine cervix by quantitative RT-PCR. The uterine cervices of female rats were excised at preovulatory, ovulatory, and postovulatory phases. The human uterine cervical adenocarcinoma cells (TCO-2) were cultured for 24 h in serum-free medium containing 17beta-estradiol or progesterone. Expression of IgBF and PDI mRNAs was significantly highest during the ovulatory phase. 17beta-estradiol stimulated the expression of both mRNAs in TCO-2; whereas progesterone was ineffective. In conclusion, estrogen regulates the production of IgBF by the endocervix and PDI in vivo, thereby increasing the level of activated IgBF in the female reproductive tract during the ovulatory phase, allowing sperm to enter the uterine cavity.
Animals↗
Bovine heart cytochrome c oxidase.
Explore the source record for details and available documents.
Animals↗
T-cell receptor vbeta usage of xeno-MHC-restricted CD4(+) T cells in concordant xenoantigen recognition.
Explore the source record for details and available documents.
Animals↗
X-ray structure and the reaction mechanism of bovine heart cytochrome c oxidase.
X-ray structure of bovine heart cytochrome c oxidase in the fully oxidized state shows a peroxide bridging between Fe2+ and Cu2+ in the O2 reduction site. The bond distances for Fe-O and Cu-O are 2.52 and 2.16 A, respectively. The structure is consistent with antiferromagnetic coupling between the two metals, which has long been known and to recent redox titration results [J. Biol. Chem. 274 (1999) 33403]. The trigonal planer coordination of Cu1+ in the O2 reduction site is consistent with the very weak interaction between Cu1+ and O2 bound at Fe2+ revealed by time-resolved resonance Raman investigations. One of the three histidine imidazoles coordinated to the Cu ion in the O2 reduction site fixes a tyrosine phenol group near the O2 reduction site with the direct covalent link between the two groups. The structure suggests that the phenol group is the site for donating protons to the bound O2. Redox-coupled conformational change in an extramembrane loop indicates that an aspartate (Asp51) in the loop apart from the O2 reduction site is the site for proton pumping.
Animals↗
X-ray structure of azide-bound fully oxidized cytochrome c oxidase from bovine heart at 2.9 A resolution.
Two azide ions were identified, one between the Fe and Cu atoms in the O(2)-reduction site and the other at the transmembrane surface of the enzyme, in the crystal structure of the azide-bound form of bovine heart cytochrome c oxidase at 2.9 A resolution. Two geometries, a mu-1,3 type geometry between the Fe and Cu atoms and a terminal geometry on the Fe atom, are equally possible for an azide ion in the O(2)--reduction site. The other azide molecule was hydrogen bonded to an amide group of an asparagine and a hydroxyl group of tyrosine in a mu-1,1 type geometry. The antisymmetric infrared bands arising from these azide ions, which show essentially identical intensity [Yoshikawa & Caughey (1992), J. Biol. Chem. 267, 9757-9766], strongly suggest terminal binding of the azide to Fe. The electron density of all three imidazole ligands to Cu(B) was clearly seen in the electron-density map of the azide-bound form of bovine heart enzyme, in contrast to the crystal structure of the azide-bound form of the bacterial enzyme [Iwata et al. (1995), Nature (London), 376, 660-669], which lacks one of the three imidazole ligands to Cu(B).
Animals↗
Pathogenic mechanism of mouse brain damage caused by oral infection with Shiga toxin-producing Escherichia coli O157:H7.
In a previous study, we showed that infection with Shiga toxin (Stx)-producing Escherichia coli O157:H7 (strain Sm(r)N-9) caused neurologic symptoms in malnourished mice with positive immunoreactions of Stx2 in brain tissues. The present study explores the mechanism of how Stx injures the vascular endothelium to enter the central nervous system in mice. Oral infection with strain Sm(r)N-9 elicited a tumor necrosis factor alpha (TNF-alpha) response in the blood as early as 2 days after infection, while Stx was first detected at 3 days postinfection. In the brain, TNF-alpha was detected at day 3, and its quantity was increased over the next 3 days. Frozen sections of the brains from moribound mice contained high numbers of apoptotic cells. Glycolipids recognized by an anti-Gb3 monoclonal antibody were extracted from the brain, and purified Stx2 was able to bind to the glycolipids. In human umbilical vascular endothelial cells (HUVEC) cultured with fluorescein-labeled Stx2 (100 ng/ml), TNF-alpha (20 U/ml) significantly facilitated the intracellular compartmentalization of fluorescence during 24 h of incubation, suggesting the enhanced intracellular processing of Stx2. Consequently, higher levels of apoptosis in HUVEC were found at 48 h. Short-term exposure of HUVEC to Stx2 abrogated their apoptotic response to subsequent incubation with TNF-alpha alone or TNF-alpha and Stx2. In contrast, primary exposure of HUVEC to TNF-alpha followed by exposure to Stx2 alone or TNF-alpha and Stx2 induced apoptosis at the same level as obtained after 48-h incubation with these two agents. These results suggest that the rapid production of circulating TNF-alpha after infection induces a state of competence in vascular endothelial cells to undergo apoptosis, which would be finally achieved by subsequent elevation of Stx in the blood. In this synergistic action, target cells must be first exposed to TNF-alpha. Such cell injury may be a prerequisite to brain damage after infection with Stx-producing E. coli O157:H7.
Animals↗
Reaction mechanism of bovine heart cytochrome oxidase.
Explore the source record for details and available documents.
Animals↗
Axon routing across the midline controlled by the Drosophila Derailed receptor.
In nervous systems with symmetry about the midline, many neurons project axons from one side to the other. Although several of the components controlling midline crossing have been identified, little is known about how axons choose the appropriate pathway when crossing. For example, in the Drosophila embryo axons cross the midline in one of two distinct tracts, the anterior or posterior commissure (AC or PC, respec tively). Here we show that the Derailed (Drl) receptor tyrosine kinase is expressed by neurons that project in the AC, and that in the absence of Drl such neurons often project abnormally into the PC. Conversely, misexpression of Drl in PC neurons forces them to cross in the AC. The behaviour of Drl-misexpressing neurons and the in vivo binding pattern of a soluble Drl receptor probe indicate that Drl acts as a guidance receptor for a repellent ligand present in the PC. Our results show that Drl is a novel component in the control of midline crossing.
Animals↗