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Biomedical subjects

Y Harada

Publications and source records attributed to Y Harada.

At least 595 records · Page 33Linked to original sources
PubMed1988

Intracellular Ca2+ mobilization in immature and more mature U937 induced to differentiate by dimethyl sulfoxide or phorbol myristate acetate.

Intracellular Ca2+ mobilization in U937 cells was studied. Stimulation of immature U937 cells with leukotriene B4 (LTB4) increased intracellular Ca2+ levels, whereas stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) failed to increase intracellular Ca2+ levels. U937 cells cultured with 1.5% dimethyl sulfoxide (DMSO) for 4 days (DMSO-U937 cells) responded to LTB4 and possessed the ability to respond to fMLP. U937 cells cultured with 1 ng/ml phorbol myristate acetate (PMA) for 4 days (PMA-U937 cells) lost the ability to respond to LTB4, although they responded to fMLP. Treatment of DMSO-U937 cells with 100 ng/ml PMA for 3 min suppressed intracellular Ca2+ increase induced by LTB4 and fMLP. The fMLP-induced Ca2+ rise in PMA-U937 cells was not suppressed by a further treatment with 100 ng/ml PMA. DMSO-U937 cells responded to inositol 1,4,5-trisphosphate (IP3), indicating that IP3 functions as a messenger of intracellular Ca2+ mobilization from endoplasmic reticulum in U937. The magnitude and duration of the rise in Ca2+ induced by IP3 in DMSO-U937 cells treated with 100 ng/ml PMA for 3 min were similar to those of the controls. When DMSO-U937 cells were Ca2+-depleted, addition of Ca2+ resulted in a transient overshoot of Ca2+ influx. However, the transient overshoot was not observed, when PMA-U937 cells were tested. These results indicate that Ca2+ efflux in PMA-U937 cells is increased by an activated exit pump, which may be directly or indirectly related to the functional state of PMA-U937 cells.

Calcium↗
PubMed1988

Demonstration of beta 1-adrenoceptor mediating relaxation of porcine coronary artery by radioligand binding and pharmacological methods.

beta-adrenoceptors in the porcine coronary artery were characterized by a radioligand binding assay using (-)-[3H]dihydroalprenolol (DHA) and also by measuring the relaxant response of isolated coronary artery to norepinephrine. Specific (-)-[3H]DHA binding in the porcine coronary artery was saturable, reversible and of high affinity (Kd = 1.6 nM) with a maximal number of binding sites of 63 fmol/mg protein, and it showed a pharmacological specificity as well as stereoselectivity which characterized beta-adrenoceptors. The Hofstee analysis of inhibition of (-)-[3H]DHA binding by atenolol, practolol and ICI 118551 has shown that the averaged concentration of beta 1 and beta 2-adrenoceptors in this tissue was 68% and 32% respectively. The relaxant response of isolated coronary artery to norepinephrine was competitively antagonized by (-)propranolol, (+)propranolol, atenolol, practolol and ICI 118551. The pA2 values of these adrenoceptor antagonists were significantly correlated with the Ki values for beta 1 but not beta 2-adrenoceptors determined by the (-)-[3H]DHA binding assay. Thus, the present study demonstrates that the relaxant response of porcine coronary artery to norepinephrine is predominantly mediated through the stimulation of beta 1-adrenoceptors on vascular smooth muscles.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1988

Application of the "imaging plate" to TEM image recording.

The "imaging plate" is a highly sensitive image recording plate for X-ray radiography, which is coated with photo-stimulable phosphor. The imaging plate is exposed to electrons in a transmission electron microscope. Its fundamental properties (sensitivity, dynamic range and sharpness) have been estimated in detail. Also, the image quality of the imaging plate for some specimens in a transmission electron microscope has been estimated. As a result, it has been ascertained that the imaging plate has superior properties and high practicability as an image recording material in a transmission electron microscope.

Animals↗
PubMed1988

Distribution of bone strength in the proximal tibia.

Indentation tests were used to determine the ultimate strength of the proximal tibia. Measurements were made at the subchondral bone surface and on transverse planes up to 25 mm below the surface. Medial condyles were stronger than lateral condyles, and in both cases bone strength decreased abruptly with distance from the surface, especially over the first 5 mm. The mean bone strength was greater in men than in women in both condyles, especially in the harder upper layers. The areas of greatest strength on both the medial and lateral sides varied with depth. At the surface, maximum strength in the medial region was more posterior in men than in women. With increasing depth, the area shifted medially in the medial region and laterally in the lateral region. Spatial distribution of strength across planes of the tibia seems consistent with anticipated patterns of load distribution in weight bearing and with the contiguity of the trabecular bone. The data are relevant to an understanding of normal joint mechanics and to the design and placement of prostheses in total knee arthroplasty.

Aged↗
PubMed1988

Cardiac pacemaker regulated by respiratory rate and blood temperature.

A new method using respiratory rate and temperature as the guides for optimal pacing is proposed. A pacemaker was fabricated which senses these two parameters simultaneously. The pacemaker functions by calculating the cardiac rate, which would be derived from the respiratory rate and the blood temperature. The higher of the two rates is adopted as the cardiac pacing rate, i.e., at which stimuli will be delivered. The operation was tested in a mongrel dog with complete atrioventricular block. After the induction of anesthesia, a thermistor temperature probe was inserted into right atrium and a respiratory rate sensor was attached around the chest. After administration of a pyrogenic drug, both respiratory rate and blood temperature increased. The pacing rate was increased from 178 beats/minute(bpm) at 36.4 degrees C, blood temperature, and 26.5 acts/minute(apm), respiratory rate, to 233 bpm at 40.1 degrees C and 40.0 apm. Cardiac output was increased from 2.15 liters/minute(l/pm) at the beginning to 2.50 l/pm at maximum. The transition of the guide from respiratory rate to temperature was observed at about 38 degrees C.

Animals↗
PubMed1988

Three-dimensional SEM study of arteriovenous anastomoses in the dog's tongue using corrosive resin casts.

Arteriovenous anastomoses (AVAs) participate in the regulation of blood flow. Although it has been speculated that AVAs in the dog's tongue play a role in the regulation of the body temperature, no published work is available on the structural characteristics of AVAs in the dog's tongue. The purpose of the present investigation was therefore to determine the frequency of AVAs and their structural characteristics by the fabrication of vascular corrosive resin casts and examination under a scanning electron microscope. This method permitted not only the visualization of the three-dimensional characteristics of AVAs, but also a clear differentiation between arterioles and venules. The total number of AVAs in the mucosal lamina propria of the dorsum of the left tongue half was 2,292. Several essential types such as S-shaped, hook-shaped, straight, bibranching and Y-shaped AVAs were observed, of which the S-shaped and similar types constituted the overwhelming majority; Y-shaped types have never been reported heretofore. This study also revealed that the locations where AVAs were most often distributed were, in descending order of frequency, the tip, the corpus and the root area of the tongue. This high frequency and strategic location of AVAs in the tongue strongly indicate that AVAs of the dog's tongue participate in the thermal regulation.

Animals↗
PubMed1988

Electronmicroscopic observation of the human facial nerve.

The facial nerves of Bell's palsy, Ramsay-Hunt's syndrome and traumatic facial palsy patients were studied using a transmission electron microscope. Changes were a proliferation of the collagen fibres, the degeneration of the Schwann cell, and a loosened or deteriorated myelin sheath. These changes differ considerably between individuals. Changes also vary in one subject. The cause and severity of the lesion, the duration of the palsy and the location of biopsy are possibly responsible for this phenomenon.

Adult↗
PubMed1988

The glycocalyx of inner ear sensory and supporting cells.

The ultrastructure of the glycocalyx of the sensory and the supporting cells of guinea pig inner ear was studied using the ruthenium red staining technique. The glycocalyx was found over the entire length of the stereocilia and the kinocilium of the sensory cells as well as over the entire apical surface of the supporting cells appearing as a fuzzy filamentous layer. The mechanism of sensory hair fusion and its relationship to glycocalyx in gentamicin treated animals was also studied. The sensory hair degeneration process started with a decrease or even a loss of glycocalyx ensued by a local attachment of neighbouring sensory hairs. These findings have led to two hypotheses about the function of the glycocalyx of the sensory hairs. Firstly the glycocalyx serves as anchoring structure for the mechanical coupling between the ciliary structures so that when a single hair in the bundle is deflected, all stereocilia and kinocilium within that bundle move in unison as a group. Secondly, because of the electronegativity of its acidic groups, the glycocalyx serves to maintain, by repulsion, a distance between adjacent cilia, preventing close contact and preventing the cell membranes from fusing.

Animals↗
PubMed1988

Hexacosanoate contents in Japanese common foods.

Recently, a diet enriched in oleate and moderately restricted in hexacosanoate (C26:0) was found effective to reduce the plasma very long chain fatty acid (VLCFA) levels in patients with adrenoleukodystrophy (ALD), an X-linked disorder characterized by demyelination of the adrenal cortex and cerebral white matter, and accumulation of saturated VLCFA, particularly C26:0, in tissues of the demyelination. The information about the C26:0 content in Japanese food was, however, almost nil except for one report about foods in the USA, but this did not include some Japanese common foods. With the hope of treating an ALD patient in our hospital, C26:0 contents in Japanese common foods (42 items) were measured. In our case, a one-hour direct transesterification method was used to obtain methylesters of total fatty acids in foods and they were applied directly to a selected ion monitoring gas chromatography-mass spectrometry for the quantitative C26:0 analysis. The C26:0 content in nuts and seeds as well as in fats and oils was found to be significantly higher than in other foods; the content was highest in peanuts. The content in almost all kinds of examined fishes, the common protein foods in Japan, was relatively low. From these data and that in the national nutrition survey in 1986, the daily intake of C26:0 from the average Japanese diet could be estimated to be 12-36 mg. It can be recommended, therefore, that nuts and seeds as well as fats and oils should be restricted as severely as possible from the diet of ALD patients in Japan in order to keep daily C26:0 intake below 10 mg as recommended in the USA.

Adrenoleukodystrophy↗
PubMed1988

Lumbar degenerative kyphosis. Clinical, radiological and epidemiological studies.

We suggest that lumbar degenerative kyphosis be included as one of the abnormal sagittal curvatures in which a kyphosis or a marked loss of lordosis is seen in the lumbar spine, caused by degenerative changes in middle-aged and elderly. One hundred and five consecutive patients were investigated, most of whom complained of low-back pain, often with a long history. They all walked in a forward bending posture, either all the time or only when exhausted. In roentgenograms, most cases showed a marked loss of the sacral inclination, as well as multiple disc narrowing and/or vertebral wedging in the lumbar region. These subjects showed a definite weakness of the lumbar extensors compared to the flexors, and therefore a reversed ratio of extensors/flexors muscle power compared with normal controls and other types of spinal curvatures. Weakness of the lumbar extensors was clearly shown by isokinetic measurement and a marked atrophy of these muscles with fatty infiltration was demonstrated by CT scanning.

Aged↗
PubMed1988

Analysis of melanoma antigen and its involvement in tumor-escape mechanisms.

Melanoma antigen was characterized by using the C57BL/6 mouse melanoma (B16) system, especially in relation to escape mechanisms of tumor cells from immunological surveillance. The antigen on the surface of melanoma cells selectively induced double negative cytotoxic T lymphocytes (CTL) lacking genetic restriction specificity in their action, whereas the soluble antigen shed or secreted from the cells preferentially induced suppressor T cells (Ts) inhibiting CTL generation in the induction phase. The epitopes of melanoma antigen for CTL and Ts were found to possess a "GM3-like structure". Anti-melanoma CTL activity was blocked by either GM3(NeuAc)-or GM3(NeuGc)-liposomes. Moreover, the GM3 (NeuGc)-liposome could induce anti-melanoma CTL when used as an antigen in the in vitro primary response. On the other hand, the soluble melanoma antigen or GM3(NeuAc)-but not GM3(NeuGc)-liposome itself specifically induced anti-melanoma Ts. Therefore, anti-melanoma Ts are able to distinguish GM3 molecular species. We also found two types of T cells, C3T4+ and double negative I-J+ T cells, to be involved in this suppression. Although the primary structure of melanoma GM3 was demonstrated to be the same as that of normal GM3, syngeneic anti-melanoma GM3 monoclonal antibody (M2590) did distinguish melanoma from normal cells. Further close analysis in liposome lysis experiments using various concentrations of GM3 clearly demonstrated that M2590 anti-melanoma GM3 only reacted with GM3 at a "high" density (more than 10-12 mol%), whereas no reactivity was observed at a "low" density (less than 7.5 mol%). It is clear, therefore, that the density of GM3 with normal primary structure is important in generating melanoma antigenicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗