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Biomedical subjects

T Komuro

Publications and source records attributed to T Komuro.

At least 55 records · Page 3Linked to original sources
PubMed1995

Long-lasting activation of cation current by low concentration of endothelin-1 in mouse fibroblasts and smooth muscle cells of rabbit aorta.

1. Recombinant human ETA receptors were expressed in a mouse fibroblast cell line (Ltk- cell) and functional coupling of the receptors with Ca2+ permeable channels at low concentrations of endothelin-1 (ET-1) was investigated using whole-cell recordings and monitoring the changes in intracellular free Ca2+ concentrations ([Ca2+]i) with a Ca2+ indicator, fluo-3. A similar type of coupling was investigated in freshly dispersed vascular smooth muscle cells (VSMCs) of rabbit thoracic aorta by use of whole-cell recordings. 2. In Ltk- cells expressing recombinant human ETA receptors, concentrations of ET-1 (10(-8) M, 10(-9) M) evoked an initial transient peak and a subsequent sustained elevation in [Ca2+]i whereas a lower concentration of ET-1 (10(-10) M) evoked only a sustained elevation of [Ca2+]i. After removal of extracellular Ca2+, ET-1 evoked only an initial peak without a sustained elevation of [Ca2+]i. The sustained elevation induced by 10(-10) M ET-1 was blocked by 300 microM mefenamic acid (a cation channel blocker) but not by 10 microM nifedipine (a blocker of voltage-operated Ca2+ channel). 3. In whole-cell recordings with Ltk- cells, a brief (3-5 min) application of ET-1 (10(-10) M) induced a sustained inward current at a holding potential of -60 mV. The current-voltage relationship revealed that the reversal potential of the ET-1-induced current was close to 0 mV (1.9 mV) and was not altered by reducing the concentration of Cl- in the bath solution, indicating that the current is carried by cations. The current was reversibly blocked by 300 microM mefenamic acid, and it persisted after all cations in the bath solution had been replaced by Ca2+ (5 or 30 mM) and nonpermeant cation N-methyl-D glucamine,indicating that the ET-1-activated channel is permeable to Ca2+. Activation of the current was independent of membrane potential and the current was induced even after addition of a high concentration (10 mM) of a Ca2+ chelator, EGTA, to the pipette solution.4. In whole-cell recordings from rabbit aortic VSMCs, ET-l (101-10 M) induced a sustained inward current at a holding potential of -60 mV. The reversal potential was - 12 mV and was not altered when the concentration of Cl- in the pipette solution was decreased, indicating that the current is carried by cations. Again activation of the current was independent of membrane potential and was observed even after addition of a high concentration (10 mM) of a Ca2+ chelator, EGTA to the pipette solution. The current was reversibly blocked by 300 microM mefenamic acid and was permeable to Ca2+,showing marked similarities to ET-1-induced cationic current in Ltk- cells.5. These results indicate that in Ltk- cells transfected with cDNA for recombinant ETA receptors andVSMCs, ETA receptors can functionally couple with a nonselective cation channel permeable to Ca2+.Thus the present data suggest that the cation channel plays an essential role in the sustained elevation of[Ca2+]i at low concentrations of ET-l by causing Ca2+ entry through the channel.

Aniline Compounds↗
PubMed1995

Molecular and structural requirements of a lipoteichoic acid from Enterococcus hirae ATCC 9790 for cytokine-inducing, antitumor, and antigenic activities.

Comparison was made between the immunobiological and antigenic properties of two lipoteichoic acid (LTA) fractions (LTA-1 and -2) from Enterococcus hirae ATCC 9790, their glycolipid portions, and synthetic compounds partially mimicking the above bacterial products. The more lipophilic LTA-2 fraction was capable of inducing serum tumor necrosis factor alpha and interleukin-6 in muramyldipeptide-primed mice and serum gamma interferon in those primed with Propionibacterium acnes. The LTA-2 fraction also induced tumor necrosis factor alpha, interleukin-6, and thymocyte-activating factor (essentially interleukin-1) in murine peritoneal macrophage cultures. Consecutive intravenous injections of muramyldipeptide and the LTA-2 fraction in Meth A fibrosarcoma-bearing BALB/c mice caused hemorrhagic necrosis and marked regression leading to complete regression of the tumor with no accompanying weakening or lethal effects. The LTA-2 fraction was at least 10,000-fold less pyrogenic in rabbits than a reference endotoxic lipopolysaccharide. The more hydrophilic LTA-1 fraction, on the other hand, showed at most marginal activity in the in vivo and in vitro assays. Natural glycolipids (NGL-1 and -2) which were prepared from a chloroform-methanol extract of Streptococcus pyogenes and E. hirae cells, and comparable in structure to the lipid moieties of the LTA-1 and -2 fractions, respectively, were practically inactive in all of the assays. None of the test synthetic compounds was immunobiologically active, although synthetic partial counterparts of the structure of LTA proposed by W. Fischer (Handb. Lipid Res. 6:123-234, 1990) reacted with murine monoclonal antibody TS-2, which was raised against OK-432, a penicillin-killed S. pyogenes preparation, and capable of neutralizing the cytokine-inducing activities of the LTA-2 fraction.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1995

[Application of enzyme-linked immunosorbent assay (ELISA) to the medico-legal identification].

Medico-legal identification of saliva stains and bloodstains was performed by an enzyme-linked immunosorbent assay (ELISA) using a horseradish peroxidase conjugate in combination with the use of monoclonal antibodies. Activity of alpha-amylase in the stains was measured for an identification of saliva using an anti-human amylase antibody, and secretory IgA was detected for a species identification using an anti-IgA antibody. ABO and Lewis blood group antigens were detected using anti-A, anti-B, anti-H, anti-Lea and anti-Leb antibodies. After the solubilization of ABH antigens in blood stains with octyl-beta-D-glucose solution, ABO typing has been performed using fully automated system composed of a unit for blood group reaction based on ELISA and a unit for reading of result based on photometric analysis.

ABO Blood-Group System↗
PubMed1995

Ultrastructure of the zinc iodide-osmic acid stained cells in guinea pig small intestine.

This study has demonstrated that cells stained using the zinc iodide-osmic acid (ZIO) method have the same fine structural features as those of fibroblasts. They have a well developed Golgi apparatus, granular endoplasmic reticulum and many mitochondria. They have no basal lamina. They are distributed in association with the deep muscular plexus, within the outer circular muscle layer and in the space between the circular and longitudinal muscle layers. Since this staining method is believed to co-stain nerves and interstitial cells of Cajal, we concluded that these ZIO-positive, fibroblast-like cells represent at least some, if not all, of the interstitial cells which appeared in the original description by Cajal.

Animals↗
PubMed1995

[Sex determination from dental calculus by polymerase chain reaction (PCR)].

We studied sex determination from dental calculus by the PCR method using primers which recognize DYZ3 region of Y-chromosome and DXZ1 of X-chromosome. The amounts of DNA obtained from 1.7-25.0 mg of dental calculus samples ranged 0.6-26.4 micrograms, and the majority of DNA was low molecular weight DNA. After PCR amplification, Y and X products were observed by the method of polyacrylamide gel electrophoresis. Both Y and X amplification products were observed in 26 out of 29 male samples, while, Y products was not detected in two samples and neither Y nor X product was detected in one sample. In 17 out of 20 female samples, only X product was observed, while, Y and X products were observed in three samples. The minimum amount of DNA for sex determination was 3 pg. Sex determination using DNA in dental calculus will be quite useful for forensic application because it can be done without destruction of morphological characteristics of teeth.

DNA↗
PubMed1995

Functional coupling of ETA receptor with Ca(2+)-permeable nonselective cation channel in mouse fibroblasts and rabbit aortic smooth-muscle cells.

Endothelin-1 (ET-1) induces persistent vasoconstriction via a sustained increase in intracellular free Ca2+ concentrations ([Ca2+]i). The mechanisms of the elevation of [Ca2+]i operating at physiologically low concentrations of ET-1 are controversial. Here we report that both native ETA receptors in vascular smooth-muscle cells and recombinant ET(A) receptors expressed in mouse fibroblasts (Ltk cells) are functionally coupled with a non-selective cation channel, which is permeable to Ca2+ and is blocked by mefenamic acid. The channel is persistently activated by a low concentration of ET-1 (10(-10) M) without stimulation of inositol triphosphate (IP3) formation and mediates sustained vasoconstriction.

Animals↗
PubMed1994

[Preclinical studies for development of anti-cancer drugs: current and historical status and problems].

In this review, we present the current and historical status of preclinical studies for development of new anti-cancer drugs. In our company, especially focusing on the stage of drug screening, pharmacology, toxicology and pharmacokinetic studies. We have discovered numerous new compounds with anti-cancer potential mainly with microbial origins, from which some drugs have been developed to clinical trials. We hope that clinical trials of drugs with a new mode of action will be designed and conducted with a more rational basis, and followed by analysis of the pharmacokinetics and pharmacodynamics so as to predict the toxicity and efficacy of the drugs in humans.

Animals↗
PubMed1994

Application of a new morphometry system based on SEM stereo-pairs to the study of intestinal mucosa of rodents.

A new morphometry system for submicroscopic three-dimensional structures was developed on the same principles as for the aerial survey using SEM stereo-pairs. This computer graphic system was applied to the analysis of the surface features of the intestinal mucosa. After removing the epithelial layer by prolonged osmication, core structures of the intestinal villi were exposed and 100 villi each from rat and mouse were measured. Average height, basal area and surface area of a single core of the rat were 188 microns, 20,200 microns2 and 93,500 microns2, respectively. Those of the mouse were 148 microns, 7,530 microns2 and 37,100 microns2, respectively. Surface amplifications by the rat and the mouse villi, after compensating for epithelial thickness, were calculated as 3.5 and 4.3, respectively; though amplifications based on the villous core were 4.6 and 4.9, respectively. These three-dimensional features of the intestinal mucosa were illustrated as submicroscopic maps by drawing their contour lines. It was demonstrated that the present morphometry system makes it possible to know not only the average features of a large sample, but also a variety of features of individual structures which were directly observed under SEM.

Animals↗
PubMed1993

[Sex determination with a discriminant function analysis of deciduous teeth size in plaster models].

Plaster models of the teeth of 3-year-old Japanese children (96 males, 98 females) were used to record the crown length, crown width and crown thickness of 5 maxillary and 5 mandibular deciduous teeth (30 measurement values). These measurements were used to devise a number of sex determination formulae. A sex-determination formula using all 30 values was calculated. Furthermore, a number of practical formulae were derived from only the crown width and crown thickness values because the deciduous teeth wear in 4 years and older children rapidly progress, making the crown length measurement unreliable. These formulae were calculated for the maxillary teeth alone and mandibular teeth alone. The formulae based on only the crown width or thickness were also calculated for both maxillary and the mandibular teeth. A step-wise discriminant analysis was then used to ascertain the most reliable measurements and a practical formula subsequently devised. The results obtained were as follows: 1. The mean value for each measurement was greater in males than in females. 2. Significant differences in the values recorded were seen in 28 out of the 30 measurements taken. The measurement items not exhibiting these significant differences were the crown width of the maxillary lateral incisor and the crown thickness of the mandibular second molar. 3. The accuracy rates for the sex-determination analysis and the step-wise sex determination analysis calculated using all 30 values were 78.6% and 75.7%, respectively. 4. The accuracy ranges for the modified sex-determination formulae and the associated step-wise sex determination analyses were 70.6-78.4% and 67.0-76.8%, respectively.

Child, Preschool↗
PubMed1993

Detection of low molecular size lipopolysaccharide contaminated in dialysates used for hemodialysis therapy with polyacrylamide gel electrophoresis in the presence of sodium deoxycholate.

Dialysis membranes are generally considered to be impermeable for bacterial endotoxin (lipopolysaccharide, LPS) contaminated in dialysates used for hemodialysis therapy, since LPS molecular size in aqueous media has been reported to be more than 10(6). However, there are few reports concerning its size in dialysates. We have already presented a newly developed polyacrylamide gel electrophoresis with sodium deoxycholate (DOC-PAGE) which proves the LPS size. Using this method, therefore, we attempted to clarify the size of LPS in dialysates. We demonstrated that LPS in dialysates had roughly two different molecular sizes with DOC-PAGE and that compared to migration profiles of Salmonella LPS as controls on DOC-PAGE, one molecular size of LPS was approximately 4,000 and the other in tens of thousands. This investigation indicates the possibility of LPS transfer across dialysis membranes.

Deoxycholic Acid↗
PubMed1992

The cellular network of interstitial cells associated with the deep muscular plexus of the guinea pig small intestine.

Systematic examination using electron microscopic montages and serial sections has demonstrated that three types of interstitial cell, namely gap junction-rich cells, glycogen-rich cells and fibroblast-like cells, are densely located along the whole extent of the deep muscular plexus of the guinea pig small intestine. They tend to be distributed in an alternating fashion in the cellular network, connected with muscle cells of the outer, circular layer by means of gap junctions. These three types of interstitial cell show close relations to two types of nerve varicosity: one type is characterized by clear round vesicles with diameters of about 50 nm, and the other by flattened vesicles measuring about 35 nm by 70 nm. Electron-dense patches have been observed at the cytoplasmic side of the axonal membranes. Muscle cells of both inner and outer circular layers also show close relations to these two types of nerve varicosity. These morphological features are discussed with the implication that they may have some regulatory role in intestinal movement.

Animals↗
PubMed1992

Interstitial cells associated with the deep muscular plexus of the guinea-pig small intestine, with special reference to the interstitial cells of Cajal.

Interstitial cells associated with the deep muscular plexus of the guinea-pig small intestine were studied by electron microscopy, and three-dimensional cell models were reconstructed from serial ultrathin sections with a computer graphic system. Three types of cells were recognized. The first type was similar in shape to smooth muscle cells, but did not contain an organized contractile apparatus. Many large gap junctions comprising about 4% of the cell surface were present; they connected cells of the first type to each other, to the second type of cell and to smooth muscle cells of the outer circular layer. The second type of cell had a well-demarcated cell body with long slender processes and was characterized by a large amount of glycogen comprising about 9% of the cell volume. The third type of cell was similar to fibroblasts, and contained well-developed Golgi apparatus and rough endoplasmic reticulum. Some of these fibroblast-like cells (a possible subtype) formed small gap junctions. All three types of cells showed close relationships with nerve varicosities. This cellular network consisting of gap-junction-rich cells, glycogen-rich cells and smooth muscle cells may be involved in the pacemaking activity of intestinal movement.

Animals↗
PubMed1992

[Quality tests for ibuprofen preparations].

Ibuprofen preparations were tested with a view to checking their quality by physical methods such as determination, disintegration and dissolution tests. These studies were carried out on 48 kinds of commercial ibuprofen preparations. The drug content of each preparation was measured by spectrophotometry (264nm), and the values were in the range of 90-110%. In the disintegration tests of 36 tablets, a few tablets of two preparations failed to disintegrate completely after 60 minutes. However the number of such tablets was within the limit specified in JP. The dissolution test described in the USP monograph was also applied to the 36 tablets, and it was found that 9 tablets failed the test provision that over 70% of the tablets must be dissolved within 30 minutes.

Ibuprofen↗
PubMed1991

The liver and the hematolymphoid system: I. The regulation of nylon-passed spleen cell proliferation by active factors released from syngeneic nonparenchymal liver cells.

Nylon-passed spleen cells were found to proliferate when cultured with syngeneic nonparenchymal adherent liver cells and their culture supernatants. The supernatants contained IL-1, IL-6, GM-CSF, and IFN (alpha + beta) activities but not IL-2 and IL-3 activities. The IFN level was higher in early culture sup (2-24 hr) than in later culture sup (48-72 hr). Proliferation was greatly increased by anti-IFN (alpha + beta) serum in the spleen cells cultured in the earlier sup. This antiserum increased the spleen cell proliferation only slightly in the later culture sup. This suggests that nonparenchymal liver cells produce two factors, one having a suppressor, and the other an enhancer action, with IFN being one of the suppressor factors. With culture time, DNA synthesis of spleen cells increased and IL-2 and IL-3 activities were generated in the culture sup. Cells proliferated during culture were found to be morphologically lymphocytes, granulocytes, and macrophages. The mechanisms by which nonparenchymal liver cells regulate the hematolymphoid system are discussed based on our observations.

Animals↗
PubMed1991

Establishment of a new perchloric acid treatment method to allow determination of the total endotoxin content in human plasma by the limulus test and clinical application.

We established a new method of plasma treatment for the removal of interfering factors in the plasma to allow detection of endotoxin by limulus test. The limulus test used was an endotoxin-specific chromogenic test, the Endospecy test. Perchloric acid (PCA) treatment and centrifugation (PCA method) is usually used to remove interfering factors from plasma, with the precipitate being discarded and the supernatant used to detect endotoxin. As the solubilized precipitates of endotoxin-spiked plasma and some patient plasma were found to contain the Endospecy activity, we have devised a new method assaying endotoxin in both the supernatant and precipitate. This study confirmed that the solubilized precipitate of endotoxin-spiked plasma had Endospecy activity and found that the precipitate had other endotoxin activities, such as lethality in galactosamine-sensitized mice and pyrogenicity in rabbits. We also confirmed that interfering factors were completely removed from plasma samples by this new method. The endotoxin level after the new PCA method was found to be about 8 times higher than that determined after PCA treatment and the new PCA method surpasses the conventional PCA method with regard to the positive rate of endotoxin contents in clinical samples. These results indicate that the new PCA method is superior to the PCA method as a plasma pretreatment method for limulus test.

Amidohydrolases↗