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Biomedical subjects

K Kurata

Publications and source records attributed to K Kurata.

At least 19 recordsLinked to original sources
PubMed2006

Fixation-sensitive myoclonus in Lafora disease.

The authors report a patient with Lafora disease, whose myoclonus was suppressed by passive eye closure. Neurophysiologic studies disclosed that fixation was the most important enhancer of myoclonus. Magnetoencephalographic studies of visual evoked fields revealed abnormal activation of the visual corticocortical pathway via the insular cortex not seen in controls. The authors hypothesize that abnormal activation of the insular cortex may be involved in triggering the mechanism of fixation-sensitive myoclonus.

Adolescent↗
PubMed2004

Identification of peptides containing T-cell epitopes of Japanese cedar (Cryptomeria japonica) pollen allergen (Cry j 1) in dogs.

Japanese cedar (Cryptomeria japonica, CJ) pollen has been known to cause atopic dermatitis in dogs in Japan. However, since the mechanism of the CJ antigen recognition is not well understood in dogs, it is difficult to develop effective immunotherapy for atopic dermatitis caused by sensitization to CJ pollen. In order to aim at development of a peptide immunotherapy, we tried to identify T-cell epitopes of a major allergen of CJ pollen, Cry j 1, in dogs sensitive to CJ pollen allergen. Peripheral blood mononuclear cells (PBMCs) obtained from 22 dogs experimentally sensitized to CJ pollen allergen and 5 atopic dogs sensitive to CJ pollen allergen were used for mapping of T-cell epitopes of Cry j 1 using 35 kinds of synthesized overlapping peptides of Cry j 1. Reactive peptides were identified based on the results of blastogenic responses of PBMCs against the peptides when the stimulation indices were beyond 2.0. Three reactive peptides were identical in a relatively high population of experimental dogs, which were Nos. 8 (p71-90) (41%), 10 (p91-110) (50%), and 11 (p101-120) (41%). It was considered that these synthesized peptides should contain T-cell epitopes of Cry j 1 in the dogs. However, there were no reactive peptides identical among the five atopic dogs spontaneously sensitive to CJ pollen. The population of dogs experimentally sensitized to CJ pollen antigen will be used in order to investigate effects of a peptide immunotherapy using the reactive peptides. The results in atopic dogs sensitive to CJ pollen antigen will also provide useful information on necessity to develop a tailor-made immunotherapy using reactive peptides in each dog.

Allergens↗
PubMed2004

Increase of CC chemokine receptor 4-positive cells in the peripheral CD4 cells in dogs with atopic dermatitis or experimentally sensitized to Japanese cedar pollen.

BACKGROUND: Since dogs frequently develop allergic diseases, similar to those in humans, dogs represent a possible animal model for allergy in humans. In human atopic dermatitis (AD), CC chemokine receptor 4 (CCR4) has been shown to play an important role in the development of allergic inflammation of AD; however, the association between allergic reaction and CCR4 is not well understood in dogs. OBJECTIVE: To examine CCR4 expression in peripheral blood CD4+ cells in dogs that had AD and were experimentally sensitized with Japanese cedar pollen. MATERIALS AND METHODS: Peripheral blood mononuclear cells (PBMCs) were isolated from 17 dogs with AD. The proportion of CCR4+ cells in peripheral blood CD4+ cells (CCR4/CD4) was evaluated by flow cytometry and compared with that in 10 healthy dogs. Similarly, in dogs that were experimentally sensitized to Japanese cedar pollen antigen, the proportion of CCR4/CD4 was examined pre- and post-sensitization. RESULTS: The proportion of CCR4/CD4 in dogs with AD was 40.3+/-3.3%, which was significantly higher than that in normal dogs (23.6+/-4.3%) (P<0.01). In the experimentally sensitized dogs, the proportion of CCR4/CD4 was 25.4+/-2.6% at pre-sensitization and it was significantly increased (29.8+/-2.9%) at post-sensitization (P<0.01). CONCLUSION: The proportion of CCR4+ cells in peripheral blood CD4+ cells was measured in dogs with allergic conditions. The present findings indicate that CCR4+ cells may be involved in the pathogenesis of allergy in dogs as in humans.

Allergens↗
PubMed2003

Short-term and long-term effects of low total pressure on gas exchange rates of spinach.

In this study, spinach plants were grown under atmospheric and low pressure conditions with constant O2 and CO2 partial pressures, and the effects of low total pressure on gas exchange rates were investigated. CO2 assimilation and transpiration rates of spinach grown under atmospheric pressure increased after short-term exposure to low total pressure due to the enhancement of leaf conductance. However, gas exchange rates of plants grown at 25 kPa total pressure were not greater than those grown at atmospheric pressure. Stomatal pore length and width were significantly smaller in leaves grown at low total pressure. This result suggested that gas exchange rates of plants grown under low total pressure were not stimulated even with the enhancement of gas diffusion because the stomatal size and stomatal aperture decreased.

Atmospheric Pressure↗
PubMed2003

A new relative referencing method for crop monitoring using chlorophyll fluorescence.

The measurement of plant chlorophyll fluorescence has been used for many years as a method to monitor a plant's health status. These types of methods have been mostly relegated to the laboratory. The newly developed Relative Referencing Method allows for the measurement of chlorophyll fluorescence under artificial lighting conditions. The fluorescence signal can be determined by first taking a reference signal measurement, then a second measurement with an additional fluorescence excitation source. The first signal can then be subtracted from the second and the plant's chlorophyll fluorescence due to the second lighting source can be determined. With this simple approach, a photosynthesizing plant can be monitored to detect signs of water stress. Using this approach experiments on tomato plants have shown that it was possible to detect water stress, while the plants were continuously illuminated by fluorescent lamps. This method is a promising tool for the remote monitoring of crops grown in a CELSS-type application.

Chlorophyll↗
PubMed2003

Influence of porosity and composition of porous carriers on the uptake of nutrients.

The current paper assesses the potential of industrial solid wastes utilization such as blast furnace slag (BFS) and zeolite synthesized from fly ash (ZFA), which are effective as well as economically attractive for the uptake of phosphate and ammonium from polluted seawater. The solidification of BFS and ZFA has been developed in different proportions of BFS/ZFA (30/70, 50/50 and 70/30 (w/w)) with different porosities (25%, 40% and 52%, respectively) to cylindrical porous carriers using a Hydrothermal Hot-Pressing (HHP) method. The concentrations of heavy metals in ZFA and BFS were too low to affect the aquatic environment. The main finding is that the high rate of BFS (70%) in porous carriers enhanced phosphate uptake explained by the higher percentage of calcium (35.7%) in porous carriers and high pH conditions. The efficient ammonium uptake was observed with high rate of ZFA (70%) in porous carriers. Results found through this experimental work imply that porous carriers with BFS/ZFA proportion of 70/30 are suitable for potential practical application in the aquatic environment due to their efficient uptake of phosphate and ammonium. The choice was made upon their porosity (40%) and their compressive strength (56 kgf/cm2) which are relatively higher than those with BFS/ZFA proportion of 30/70 and 50/50.

Ammonia↗
PubMed2001

Effect of beta-estradiol on voltage-gated Ca(2+) channels in rat hippocampal neurons: a comparison with dehydroepiandrosterone.

We investigated the effects of beta-estradiol, dehydroepiandrosterone and dehydroepiandrosterone sulfate on intracellular calcium concentration ([Ca(2+)](i)) increases induced by gamma-aminobutyric acid (GABA), high K(+) and N-methyl-D-aspartate acid (NMDA) in cultured hippocampal neurons. Acute treatment with beta-estradiol, dehydroepiandrosterone and dehydroepiandrosterone sulfate inhibited the GABA-induced [Ca(2+)](i) increases to the similar extent. Tamoxifen, an estrogen receptor antagonist, did not block the inhibitory effects of beta-estradiol. On the other hand, GABA type A (GABA(A)) receptor antagonists, picrotoxin and bicuculline, blocked the GABA-induced [Ca(2+)](i) increases. Previously, we demonstrated that GABA- and high K(+)-induced [Ca(2+)](i) increases were commonly mediated by voltage-gated calcium channels (VGCCs). Therefore, we examined the effects of these steroids on the high K(+)-induced [Ca(2+)](i) increases. The inhibitory effect of beta-estradiol on the high K(+)-induced [Ca(2+)](i) increases was much greater than that of dehydroepiandrosterone and dehydroepiandrosterone sulfate. beta-Estradiol inhibited the NMDA-induced [Ca(2+)](i) increases with an IC(50) of 51.8 microM and NMDA responses were reduced to half in the presence of 10 micro M nifedipine, indicating that the NMDA-induced [Ca(2+)](i) increases also involved VGCCs. Further, we examined the inhibitory effect of beta-estradiol on the high K(+)-induced [Ca(2+)](i) increases in the presence of a N-type VGCCs antagonist, 1 microM omega-conotoxin, or a L-type VGCCs antagonist, 10 microM nifedipine. The IC(50) value of beta-estradiol alone (45.5 microM) was similar to that of omega-conotoxin (33.1 microM), while the value combined with nifedipine was reduced to 2.2 microM. beta-Estradiol also abolished the positive modulatory effect of L-type VGCCs agonist, 1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)phenyl]pyridine-3-carboxylic acid methyl ester (Bay K 8644). Our results showed that the inhibitory mechanism of beta-estradiol is different from that of dehydroepiandrosterone and dehydroepiandrosterone sulfate and beta-estradiol may act primarily at L-type VGCCs.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2001

Formation of a direction map by projection learning using Kohonen's self-organization map.

In this paper, we propose a modification of Kohonen's self-organization map (SOM) algorithm. When the input signal space is not convex, some reference vectors of SOM can protrude from it. The input signal space must be convex to keep all the reference vectors fixed on it for any updates. Thus, we introduce a projection learning method that fixes the reference vectors onto the input signal space. This version of SOM can be applied to a non-convex input signal space. We applied SOM with projection learning to a direction map observed in the primary visual cortex of area 17 of ferrets, and area 18 of cats. Neurons in those areas responded selectively to the orientation of edges or line segments, and their directions of motion. Some iso-orientation domains were subdivided into selective regions for the opposite direction of motion. The abstract input signal space of the direction map described in the manner proposed by Obermayer and Blasdel [(1993) J Neurosci 13: 4114-4129] is not convex. We successfully used SOM with projection learning to reproduce a direction-orientation joint map.

Algorithms↗
PubMed2001

Atlantoaxial subluxation in an adult secondary to retropharyngeal abscess.

Atlantoaxial subluxation secondary to a retropharyngeal abscess is well described in children, but very rare in adults. Only two adult cases have been reported in the literature. We present a case of severe atlantoaxial subluxation in an adult secondary to retropharyngeal abscess. His atlas-dens interval was very large, up to 10 mm in flexion. We tried external fixation with a neck collar initially, but for remaining instability, surgical fusion was performed. The mechanism of subluxation is attributed to softening of the ligament allowing greater mobility at the joint. The etiology of this process is speculative.

Atlanto-Axial Joint↗
PubMed2001

Molecular cloning of canine thymus and activation-regulated chemokine (TARC) gene and its expression in various tissues.

Thymus and activation-regulated chemokine (TARC) is known as a functional ligand for CC chemokine receptor 4 (CCR4), which is selectively expressed on Th2 lymphocytes and induces selective migration of the cells to allergic lesions. In this study, we cloned canine TARC cDNA from canine thymus by RT-PCR with rapid amplification of cDNA ends (RACE) method. The canine TARC clone contained a full-length open reading frame encoding 99 amino acids and included four cysteine residues characteristic to CC chemokine family. The canine TARC cDNA showed 77.5%, 67.4%, and 68.5% amino acid sequence similarity with human, mouse and rat homologues, respectively. Expression of TARC mRNA was detected not only in thymus but also in spleen, lymph node, lung and heart of the various normal dog tissues examined. TARC cDNA clone obtained in this study will be useful for further investigation on allergic diseases in dogs.

Amino Acid Sequence↗
PubMed2001

Seasonal rhinitis in a cat sensitized to Japanese cedar (Cryptomeria japonica) pollen.

A cat showing seasonal allergic symptoms of rhinitis was examined for reactivities to Japanese cedar (Cryptomeria japonica, CJ) pollen allergen by intradermal skin test (IDST), Prausnitz-Kustner (P-K) test, and lymphocyte blastogenic response. In IDST for 26 common allergens. the cat showed a positive reaction to CJ pollen allergen. P-K test using CJ pollen allergen also showed a positive reaction, indicating the presence of serum IgE specific to CJ pollen. In the lymphocyte blastogenic response, the stimulation index in the presence of CJ pollen allergen was 2.4. These data suggested that the seasonal rhinitis observed in the cat was caused by the sensitization to CJ pollen allergen.

Animals↗
PubMed2001

Mechanical strain effect on bone-resorbing activity and messenger RNA expressions of marker enzymes in isolated osteoclast culture.

Adaptive modeling and remodeling are controlled by the activities of osteoblasts and osteoclasts, which are capable of sensing their mechanical environments and regulating deposition or resorption of bone matrix. The effects of mechanical stimuli on isolated osteoclasts have been scarcely examined because it has proven to be difficult to prepare a number of pure osteoclasts and to cultivate them on mineralized substratum during mechanical stimulation. Recently, we developed an apparatus for applying mechanical stretching to the ivory slice/plastic plate component on which cells could be cultured. The loading frequency, strain rate, and generated strain over an ivory surface could be controlled by a personal computer. Using this apparatus, we examined the role of mechanical stretching on the bone-resorbing activity of the osteoclasts. Mature and highly enriched osteoclasts were cultured for 2, 12, and 24 h on the ivory/plate component while being subjected to intermittent tensile strain. The stretched osteoclasts showed enhanced messenger RNA (mRNA) expression levels of osteoclast marker enzymes, tartrate-resistant acid phosphatase (TRAP), and cathepsin K and increases of resorbed-pit formation, suggesting that the mechanical stretching up-regulated the bone-resorbing activity of the osteoclasts. A stretch-activated cation (SA-cat) channel blocker significantly inhibited the increases of the mRNA level and pit formation after 24 h of stretching. This study suggested the possibility that the mature osteoclasts responded to mechanical stretching through a mechanism involving a SA-cat channel in the absence of mesenchymal cells and, as a result, up-regulated their bone-resorbing activity.

Acid Phosphatase↗
PubMed2001

Malignant fibrous histiocytoma of soft tissue producing granulocyte colony-stimulating factor.

We treated a rare case of malignant fibrous histiocytoma (MFH) of soft tissue that produced granulocyte colony-stimulating factor (G-CSF). The patient, an 80-year-old woman, was admitted because of a feeling of abdominal fullness and leg edema. An elastic, hard, tender tumor was palpated in the right thigh. Histopathological examinations of the tumor revealed atypical and prominent pleomorphic spindle-shaped cells with funicular arrangement, which were compatible with the diagnosis of MFH. Prominent leukocytosis (up to 84,300/microl), a high serum G-CSF concentration (82 pg/ml) and positive immunohistochemical staining of the tumor tissue for G-CSF indicated that G-CSF was produced by the MFH.

Aged↗
PubMed2000

IgE-reactivity to major Japanese cedar (Cryptomeria japonica) pollen allergens (Cry j 1 and Cry j 2) by ELISA in dogs with atopic dermatitis.

The present study investigated IgE-reactivity to two major Japanese cedar (Cryptomeria japonica, C. japonica) pollen allergens (Cry j 1 and Cry j 2) in dogs with atopic dermatitis by use of a fluorometric ELISA. The serum samples from 27 dogs that showed IgE-sensitivity to crude C. japonica pollen allergen by ELISA were tested for specific IgE to the two major allergens. All 27 dogs had anti-Cry j 1 IgE, and 10 (37%) had anti-Cry j 2 IgE. Inhibition of binding of dog specific IgE to crude C. japonica pollen allergen was carried out by addition of Cry j 1. When serum samples containing anti-Cry j 1 IgE but no anti-Cry j 2 IgE were incubated with Cry j 1, specific IgE binding to crude C. japonica pollen allergen was almost abolished. These findings suggest that Cry j 1 is a major allergen in dogs.

Animals↗
PubMed2000

Positive reactions to common allergens in 42 atopic dogs in Japan.

Clinically important allergens for the diagnosis and treatment of atopic dermatitis vary geographically. In order to identify the most prevalent allergens in atopic dogs in Japan, 42 dogs with a clinical diagnosis of atopy were tested using both in vivo (intradermal skin test (IDST)) and in vitro (antigen-specific IgE assay) allergy tests. Allergens used for IDST included 26 allergen extracts from eight allergen groups: trees, weeds, grasses, house dust mites (HDM), molds, foods, epithelia, and arthropods. Immunodot assay was used to measure antigen-specific IgE against 24 allergens from these eight groups and against fish such as cod and sole. In the 42 dogs, the most common positive allergen reaction was to HDM on both IDST (29/42 dogs or 69%) and in vitro testing (23/42 or 54.8%). The second most frequent positive allergen reaction was to Japanese cedar pollen (21/42 or 50.0% for IDST and 7/42 or 16.7% for in vitro testing). In both tests, less than 20% of dogs had positive reactions to molds or foods. Positive reactions to cat epithelia were frequently found on IDST, but rarely found on in vitro testing. Agreement between the two tests was found in 26 instances: HDM (21 dogs), Japanese cedar pollen (five dogs) and wheat (one dog). In this study, the two most common allergens involved in atopic dermatitis in dogs in Japan were HDM and Japanese cedar pollen.

Allergens↗
PubMed2000

Properties of basis functions generated by shift invariant sparse representations of natural images.

The idea that a sparse representation is the computational principle of visual systems has been supported by Olshausen and Field [Nature (1996) 381: 607-609] and many other studies. On the other hand neurons in the inferotemporal cortex respond to moderately complex features called icon alphabets, and such neurons respond invariantly to the stimulus position. To incorporate this property into sparse representation, an algorithm is proposed that trains basis functions using sparse representations with shift invariance. Shift invariance means that basis functions are allowed to move on image data and that coefficients are equipped with shift invariance. The algorithm is applied to natural images. It is ascertained that moderately complex graphical features emerge that are not as simple as Gabor filters and not as complex as real objects. Shift invariance and moderately complex features correspond to the property of icon alphabets. The results show that there is another connection between visual information processing and sparse representations.

Animals↗
PubMed2000

Activation of the dorsal premotor cortex and pre-supplementary motor area of humans during an auditory conditional motor task.

Using functional magnetic resonance imaging (fMRI), we measured regional blood flow to examine which motor areas of the human cerebral cortex are preferentially involved in an auditory conditional motor behavior. As a conditional motor task, randomly selected 330 or 660 Hz tones were presented to the subjects every 1. 0 s. The low and high tones indicated that the subjects should initiate three successive opposition movements by tapping together the right thumb and index finger or the right thumb and little finger, respectively. As a control task, the same subjects were asked to alternate the two opposition movements, in response to randomly selected tones that were presented at the same frequencies. Between the two tasks, MRI images were also scanned in the resting state while the tones were presented in the same way. Comparing the images during each of the two tasks with images during the resting state, it was observed that several frontal motor areas, including the primary motor cortex, dorsal premotor cortex (PMd), supplementary motor area (SMA), and pre-SMA, were activated. However, preferential activation during the conditional motor task was observed only in the PMd and pre-SMA of the subjects' left (contralateral) frontal cortex. The PMd has been thought to play an important role in transforming conditional as well as spatial visual cues into corresponding motor responses, but our results suggest that the PMd along with the pre-SMA are the sites where more general and extensive sensorimotor integration takes place.

Acoustic Stimulation↗