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Biomedical subjects

T Kikuchi

Publications and source records attributed to T Kikuchi.

At least 577 records · Page 32Linked to original sources
PubMed1988

Variations in the disappearance rate of indocyanine green.

Time-associated changes in the disappearance rate of indocyanine green from the blood (K.ICG) as an index of liver function, were studied. Blood was drawn 5 times at 3-minute intervals from 32 patients. Early, intermediate, and late K.ICG values were 0.087 +/- 0.040, 0.082 +/- 0.038, and 0.076 +/- 0.033 min-1, respectively, showing serial decreases. When blood was drawn 8 times at 2-minute intervals from 22 other patients, the means of the K.ICG values at 11 time points showed a nearly linear relationship (r = -0.986). These findings indicated that K.ICG is approximated by a linear function of time, K(t) = -K'.t + K0. According to this function, K.ICG is considered to decrease by 1.96% every minute. The K.ICG value determined by the conventional method is, therefore, a mean disappearance rate of 15 minutes, and K0 is considered to reflect the initial reaction speed.

Cholestasis↗
PubMed1988

7-[3-(4-[2,3-Dimethylphenyl]piperazinyl)propoxy]-2(1H)-quinolinone (OPC-4392), a presynaptic dopamine autoreceptor agonist and postsynaptic D2 receptor antagonist.

7-[3-(4-[2,3-dimethylphenyl]piperazinyl)propoxy]-2(1H)-quinolinone (OPC-4392), was synthesized in our laboratories and compared with apomorphine, 3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP) and dopamine antagonists in a series of tests designed to characterize dopamine receptor activation and inhibition. The assertion that OPC-4392 acts as an agonist at presynaptic dopamine autoreceptors is supported by the following behavioral and biochemical observations: OPC-4392, 3-PPP and apomorphine inhibited the reserpine-induced increase in DOPA accumulation in the forebrain of mice and in the frontal cortex, limbic forebrain and striatum of rats. In addition, the gamma-butyrolactone (GBL)-induced increase in DOPA accumulation in the mouse forebrain was also inhibited by OPC-4392, 3-PPP and apomorphine. Haloperidol antagonized the inhibitory effect of OPC-4392 in both instances. The inhibitory effect of OPC-4392 on GBL-induced DOPA accumulation lasted for at least 8 hours after oral administration to mice, while that of 3-PPP and apomorphine disappeared in 4 hours after subcutaneous injection. OPC-4392 failed to increase spontaneous motor activity in reserpinized mice, enhance spontaneous ipsilateral rotation in rats with unilateral striatal kainic acid (KA) lesions, induce contralateral rotation in rats with unilateral striatal 6-hydroxydopamine (6-OHDA) lesions and inhibit 14C-acetylcholine (Ach) release stimulated by 20 mM KCl in rat striatal slices. In addition, OPC-4392 appears to block postsynaptic D2 receptors since OPC-4392, as well as dopamine antagonists, was able to inhibit stereotyped behavior and climbing behavior induced by apomorphine in mice, displace the 3H-spiroperidol binding to rat synaptosomal membranes in vitro and reverse the inhibitory effect of apomorphine on Ach release in rat striatal slices. These results suggest that OPC-4392 acts as a dopamine agonist at presynaptic autoreceptors related to dopamine synthesis and acts as dopamine antagonist at postsynaptic D2 receptors.

Animals↗
PubMed1988

Toxins in the skin secretion of the oriental catfish (Plotosus lineatus): immunological properties and immunocytochemical identification of producing cells.

Antiserum against toxin I, one of the lethal factors in the skin secretion from the oriental catfish (Plotosus lineatus), was used to examine immunological properties of the toxic factors and identify toxin-producing cells by an immunocytochemical technique. In immunodiffusion tests, the antiserum formed a precipitin line with toxin I while it formed no precipitin line either with another lethal factor (toxin II) or with a hemolysin. Lethal and edema-forming activities of toxin I were neutralized by the antiserum but lethal activity of toxin II and lytic activity of the hemolysin were not. These results suggested that toxin I can be antigenically distinguished from both toxin II and hemolysin. In immunocytochemical tests using the antiserum, club cells in the epidermis were positively stained, indicating that toxin I is produced in the club cells. Interestingly, venom glandular cells surrounding the dorsal and pectoral spines were also stained. The venom glandular cells appear to produce toxin I or a toxin with the same antigen determinants as toxin I.

Animals↗
PubMed1988

Purification and characterization of a lethal factor in venom from the crown-of-thorns starfish (Acanthaster planci).

A lethal factor in venom of the crown-of-thorns starfish (Acanthaster planci) was obtained in an electrophoretically pure state by chromatography on CM-cellulose and Sephadex G-100. The purified lethal factor is a basic (pI 10.6) glycoprotein (carbohydrate content 3.5%). The mol. wt was estimated to be 20,000 by gel filtration or 25,000 by SDS-disc electrophoresis, suggesting that the lethal factor has no subunit structure. Despite its basicity, the lethal factor was richer in acidic amino acids than in basic amino acids. The lethal factor had an LD50 of 0.43 mg/kg (i.p. injection into mice). Hemolytic, edema-forming and capillary permeability-increasing activities, though very weak, were also exhibited by the lethal factor, while hemorrhagic and phospholipase A activities were not present.

Amino Acids↗
PubMed1988

The role of interleukin-1 on proteoglycan metabolism of rabbit annulus fibrosus cells cultured in vitro.

The effects of human recombinant interleukin-1 alpha (IL-1 alpha) on proteoglycan (PG) metabolism of rabbit intervertebral disc were investigated morphologically and biochemically using rabbit annulus fibrosus (AF) cells in culture. AF cells could maintain their differentiated phenotype well in our primary culturing condition. In this situation, IL-1 alpha stimulated the cells and induced marked increase of PG release. Dose dependency of IL-1 alpha on PG release was seen in the concentration range between 5-50 U/ml. Caseinolytic activity produced and secreted into the medium by AF cells was assayed and it was found that IL-1 alpha enhanced the enzyme activities in the medium. The effects of IL-1 alpha on PG and DNA synthesis were also studied. Slight depression was observed in PG synthesis but there was no effect on DNA synthesis. These data suggest that IL-1 alpha may play an important role in PG metabolism of intervertebral disc cells, especially in the catabolic pathway of PG.

Animals↗
PubMed1988

Characterization of calcium transport by basolateral membrane vesicles of human small intestine.

The present studies investigated the mechanism of Ca2+ transport across basolateral membrane vesicles (BLMVs) prepared from human small intestine. Ca2+ uptake represented transport into the intravesicular space as evident by osmolality study and by the demonstration of Ca2+ efflux from the intravesicular space by Ca2+ ionophore A23187. Ca2+ uptake was stimulated by Mg2+-ATP. Kinetic parameters for ATP-dependent Ca2+ uptake revealed a Michaelis constant (Km) of 0.02 +/- 0.01 microM and a maximum rate of uptake (Vmax) of 1.00 +/- 0.03 nmol.mg protein-1.min-1.Ca2+ uptake in the absence of Mg2+ was inhibited by 75%. The Km of ATP concentration required for half-maximal Ca2+ uptake was 0.50 +/- 0.1 mM. Calmodulin (10 micrograms/ml) increased Vmax to 1.62 +/- 0.02 nmol.mg protein-1.min-1 (P less than 0.001). Km values were 0.017 +/- 0.001 microM, which was not significantly different from control values. Basolateral membranes depleted of calmodulin by EDTA osmotic shock decreased ATP-dependent Ca2+ uptake by 65%. Trifluoperazine, an anticalmodulin drug, inhibited ATP-dependent Ca2+ uptake by 50%, while no inhibition was noted in calmodulin-depleted membranes. Efflux of Ca2+ in the BLMVs was stimulated by trans-Na+. Na+-dependent Ca2+ uptake was saturable with respect to Ca2+ concentration and exhibited a Km of 0.09 +/- 0.03 microM and a Vmax of 1.08 +/- 0.01 nmol.mg protein-1.min-1. These results are consistent with the existence of a Na+-Ca2+ exchange system and ATP and Mg2+-dependent, calmodulin-regulated Ca2+, transport mechanism in BLMVs of human enterocytes.

Adenosine Triphosphate↗
PubMed1988

Effects of interleukin-1 and anti-inflammatory drugs on the degradation of human articular cartilage.

It has been suggested that metalloproteases produced by chondrocytes play an important role in cartilage breakdown in joint diseases. The aim of this study was to investigate changes in enzyme activities in human rheumatoid and osteoarthritic articular cartilage. Cartilage fragments were incubated with various drugs for 48 hours. The concentrated culture media were used as enzyme solutions. Collagenase was assayed using FITC-collagen as the substrate. Proteoglycanase (PGase) was measured either by the release of 35S-labelled proteoglycans from cartilage into the medium, or by enzyme assay using proteoglycan monomer bound to fluorescein-conjugated hyaluronic acid as the substrate. Collagenase and proteoglycanase were found only in trace amounts in the concentrated media of healthy cartilage. Interleukin-1 (IL-1) enhanced the enzyme activities significantly. Marked increases of enzyme activities were observed in the concentrated media of rheumatoid (RA) and osteoarthritic (OA) cartilage. The sensitivity to interleukin-1 was also higher in OA and RA cartilage compared with healthy cartilage. Dexamethasone (10(-6) mol/L) markedly depressed enzyme activity. Tiaprofenic acid (4 x 10(-5) mol/L) also decreased enzyme activity, whereas indomethacin (4 x 10(-6) mol/L) and naproxen (3 x 10(-4) mol/L) had no effect.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Electrogustometry of the soft palate as a topographic diagnostic method for facial paralysis.

Electrogustometry (EGM) of the soft palate, innervated by the gustatory fibers running via the greater petrosal nerve, was performed in 10 cases with facial paralysis due to suprageniculate lesions to evaluate its clinical validity as a topographic diagnostic method. Lacrimal function was also examined for comparison. The results obtained from EGM showed a significantly increased threshold on the affected side in 90% of the cases. However, the lacrimal secretion decreased only in 40% using Schirmer No. 2 test. The results of the present study strongly suggest that EGM of the soft palate reflects the function of this nerve better than Schirmer test, and EGM is clinically useful for the topographic diagnosis of peripheral facial nerve lesions.

Adult↗
PubMed1988

Osteogenic capacity of cultured human periosteal cells.

We developed a culture system of cells isolated from juvenile human periosteum. The culture consisted of epithelial-like and fibroblast-like cells. Both types of cells had intense alkaline phosphatase activity maintained in subculture. When these cells, loaded into diffusion chambers, were implanted subcutaneously in rats, cartilage tissue was mainly formed and bone was seen scantily. 1 alpha-OH-D3 and 1,25-(OH)2-D3 increased the alkaline phosphatase activity and proteoglycan synthesis in the periosteal cells. Calcitonin also stimulated the proteoglycan synthesis, but parathyroid hormone had no effect.

Alkaline Phosphatase↗
PubMed1988

Gracile axonal dystrophy (GAD), a new neurological mutant in the mouse.

A new neurological mutant has been found in the F2 offspring of CBA/Nga and RFM/Nga mice. Affected mice exhibited ataxia beginning at about 80 days of age, followed by tremor, difficulty in moving, and muscular atrophy of the hind limbs. The neurological signs became progressively severe, and death occurred by 5 to 6 months of age. Since the animals could be distinguished from normal mice by the abnormal positions of the hind limbs when the mouse was hung by the tail after 1 month of age, they could be bred until onset of the signs. Pathological examination revealed neuroaxonal dystrophy and degeneration in the gracile nucleus of the medulla oblongata and the gracile fascicules of the spinal cord, which could be the main cause of the clinical signs. The mutation is inherited as an autosomal recessive trait. It was, therefore, named gracile axonal dystrophy (GAD) with the gene symbol gad. The mice could be a new pathological model for the study of neuroaxonal dystrophy.

Animals↗
PubMed1988

[Distribution of spatial attention in position recognition].

Spatial limitation in visual information processing was examined with dot-in-matrix patterns by using a probe recognition procedure. The independent variables were the number (1-16 dots) and the position of target dots. Subjects were four undergraduate students. The data were analyzed and discussed from three points of view; span of attention, spatial limitation of recognition and visual attention. The following became clear: First, the span of position recognition was 4.8. Second, "spatial span of attention" was defined as the range of dot positions at which subjects can perceive target dots with 75% or more accuracy. It extended around the fixation point and shrinked with the increase of the number of target dots. Finally, the distribution of spatial attention was estimated for each target dot condition under the assumption that the hit RT at each probe position reflects the amount of attention allocated there. Distributions estimated were cone-shaped, and the height and extent changed with the number of target dots. It was suggested that spatial limitation (i.e. spatial span of attention) in the processing of spatial positions can be explained by the notion of distribution of spatial attention.

Attention↗
PubMed1988

[Force plate analysis of ascending and descending stairs].

Six characteristic points including maximal and minimal points of the vertical components, and antero-posterior components were determined by digitalization of floor reaction curves in ascending and descending stairs. In cases with hip or knee disorders, lengthening of phases of the characteristic points were observed in ascending stairs, while shortening of phases were seen in descending stairs. The maximum of vertical forces on affected legs decreased in ascending and descending stairs. In cases with hip disorders, characteristic points of sound legs in early stance phase were different from those of normal subjects. In cases with knee disorders, increase in vertical forces during mid-stance phase was observed.

Adolescent↗
PubMed1987

Tissue metal shifts by a single exposure to metals in rats.

Intraperitoneal pretreatment with a large dose of Cd, Zn, Hg, Mn or Ag remarkably depressed the lethal effects of X-ray. The CHX pretreatment before metal challenge depressed the lethal effects of X-ray more remarkably. Therefore, metal-binding protein may not play an important role in protective effects of metal pretreatment on the lethal effects of X-ray, but quantum mechanical characters of metals may do so.

Animals↗