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Biomedical subjects

H Higuchi

Publications and source records attributed to H Higuchi.

At least 271 records · Page 15Linked to original sources
PubMed1985

Connectin filaments link thick filaments and Z lines in frog skeletal muscle as revealed by immunoelectron microscopy.

In an earlier study connectin, an elastic protein of striated muscle, was found to be associated with "gap filaments" originating from the thick filaments in the myofibril, but it was not clear whether it extends to Z lines or not (Maruyama, K., H. Sawada, S. Kimura, K. Ohashi, H. Higuchi, and Y. Umazume, 1984, J. Cell Biol., 99:1391-1397). In the present immunoelectron microscopic study using polyclonal antibodies against native connectin, we have concluded that the connectin structures are directly linked to Z lines from the thick (myosin) filaments in myofibrils of skinned fibers of frog skeletal muscle. There were five distinct antibody-binding stripes in each half of the A band and two stripes in the A-I junction region. Deposits of antibodies were recognized in I bands and Z lines. We suggest that connectin filaments run alongside the thick filaments, starting from a region approximately 0.15 micron from the center of the A band.

Animals↗
PubMed1985

Changes in density of muscarinic cholinergic receptor by adrenergic denervation with guanethidine.

The effects of chronic adrenergic denervation with guanethidine on muscarinic cholinergic receptors (mAChR) were investigated by binding of L-3H-quinuclidinyl benzilate (3H-QNB). Guanethidine treatment decreased the amount of mAChR from 102 to 87 fmoles/mg protein in the heart and from 444 to 388 fmoles/mg protein in the small intestine, but increased it from 223 to 282 fmoles/mg protein in the vas deferens, without changes in its characteristics. These findings suggested that adrenergic innervation has different influences on the mAChR population in different tissues.

Animals↗
PubMed1985

Participation of protein synthesis in development of supersensitivity in cultured rat vas deferens.

Organ culture of rat vas deferens produced supersensitivity to norepinephrine and acetylcholine in contractile response without change in alpha 1-adrenergic and muscarinic acetylcholine receptors. The development of supersensitivity was inhibited by low temperature and protein synthesis inhibitors. However, protein synthesis inhibitor had no significant effect on the receptors. These findings suggested that the supersensitivity may be induced by synthesis of protein(s) which have a stimulatory effect in a process(es) after activation of receptor to contraction.

Acetylcholine↗
PubMed1985

[Follow-up of primary pontine hemorrhage of the young adult by CT scan].

A case of primary pontine hemorrhage of the young was reported. He was 22 years of age, who did not have the history of hypertension. He suddenly noticed disturbance of skilled act of his right hand and speech disturbance. He was admitted to our clinic two days after the onset. Neurological examination revealed right facial palsy, disturbance of delicate movement of his right hand and slight dysarthria. Lumbar puncture, after six days from the onset, yielded watery clear cerebrospinal fluid containing 6/3 cells/mm3, 27 mg/dl of protein and 65.1 mg/dl of sugar. An opening pressure was 75 mmH2O. The vertebral angiography revealed no evidence of mass lesion and vascular anomalies. CT scan demonstrated a pontine hematoma, the size of this hematoma sequentially enlarged in follow-up CT scan. His clinical symptoms were gradually aggravated, i.e. cerebellar sign, urinary disturbance and involuntary movement. Conservative therapy was performed and his symptoms gradually improved. The size of hematoma was reduced in follow-up CT scan. The genesis, diagnosis and treatment of primary pontine hemorrhage of the young were discussed.

Adult↗
PubMed1985

Effect of terminal base pairs on the CD spectra of oligodeoxynucleotide duplexes.

Oligodeoxynucleotide duplexes having terminal C:G base pairs and recognition sequences for restriction endonucleases Bgl II and Sau 3Al were synthesized by the solid or liquid phase phosphotriester approach. Among them, the self-complementary oligonucleotides with C or CC at the 5'-end and G or GG at the 3'-end exhibited unusual CD spectra in contrast to those of the usual B-DNA type CD spectra of the oligonucleotide with G or GG at the 5'-end. The spectra are different to those of the Z-DNA, and regarded to the terminal base effect of the C:G pairs.

Base Composition↗
PubMed1984

Effects of guanine nucleotide and sulfhydryl reagent on subpopulations of muscarinic acetylcholine receptors in mammalian hearts: possible evidence for interconversion of super-high and low affinity agonist binding sites.

Multiple site models of muscarinic acetylcholine receptors (mAChR) for agonist binding were applied to curves for the inhibition of QNB binding by carbachol by using nonlinear least square regression analysis. The effects of a guanine nucleotide guanyl-5'-yl imidodiphosphate (Gpp(NH)p) and a sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid (DTNB) on the curves were also analyzed. The results suggested that mAChR of dog and guinea pig heart had three types of sites with different affinities for carbachol (super-high (SH), high (H) and low (L]. In the presence of Gpp(NH)p, SH sites were eliminated and L sites increased, indicating conversion of SH sites to L sites. On the contrary, in the presence of DTNB, L sites were converted to SH sites. These results were obtained at both 37 degrees C and 0 degrees C incubation although the affinity of each site was high at 0 degrees C than at 37 degrees C. These data suggest the interconversion of SH and L sites. The possible existence of two subtypes (GTP-regulated mAChR(SH-L type) and GTP-independent mAChR (H type] is discussed.

Animals↗
PubMed1984

Connectin filaments in stretched skinned fibers of frog skeletal muscle.

Indirect immunofluorescence microscopy of highly stretched skinned frog semi-tendinous muscle fibers revealed that connectin, an elastic protein of muscle, is located in the gap between actin and myosin filaments and also in the region of myosin filaments except in their centers. Electron microscopic observations showed that there were easily recognizable filaments extending from the myosin filaments to the I band region and to Z lines in the myofibrils treated with antiserum against connectin. In thin sections prepared with tannic acid, very thin filaments connected myosin filaments to actin filaments. These filaments were also observed in myofibrils extracted with a modified Hasselbach-Schneider solution (0.6 M KCl, 0.1 M phosphate buffer, pH 6.5, 2 mM ATP, 2 mM MgCl2, and 1 mM EGTA) and with 0.6 M Kl. SDS PAGE revealed that connectin (also called titin) remained in extracted myofibrils. We suggest that connectin filaments play an important role in the generation of tension upon passive stretch. A scheme of the cytoskeletal structure of myofibrils of vertebrate skeletal muscle is presented on the basis of our present information of connectin and intermediate filaments.

Animals↗
PubMed1984

Blockade by anti-glucocorticoids, actinomycin D and cycloheximide of the anti-inflammatory action of some Kampohozai (Chinese traditional medicines) against serotonin.

Blockade by anti-glucocorticoids, progesterone and 17 alpha-methyltestosterone, a messenger ribonucleic acid (m-RNA) synthesis inhibitor, actinomycin D, and a protein synthesis inhibitor, cycloheximide, of the anti-exudative action of five kinds of Kampohozai (Daisaikoto, Shosaikoto, Saikokeishito, Daiobotanpito and Tokakujokito) were studied to investigate mode of the anti-inflammatory action of those Kampohozai. The inflammatory lesion was provoked by injection of serotonin (0.3 micrograms) in the Tyrode solution (5 microliter) in subplantar region of the hind paw of mice. The above anti-glucocorticoids and the m-RNA and protein synthesis inhibitors suppressed the anti-inflammatory effects of Daisaikoto and Shosaikoto dose-dependently. The action of Saikokeishito was suppressed weakly by treatment with progesterone or 17 alpha-methyltestosterone, but not blocked by treatment with actinomycin D or cycloheximide. On the other hand, Daiobotanpito and Tokakujokito were not blocked by treatment with those four inhibitors. These results suggest that mechanism of anti-inflammatory action of Daisaikoto and Shosaikoto is similar to that of glucocorticoid but Daiobotanpito and Tokakujokito exert anti-inflammatory effects through some other mechanisms.

Animals↗
PubMed1984

[Low level alpha activity measurements with pulse shape discrimination--the analytical system and its characteristics].

Pulse shape discrimination of alpha and beta rays with liquid scintillation counting was investigated for the purpose of low level alpha activity measurements. Various liquid scintillators for pulse shape discrimination were examined by means of pulse rise time analysis. A new scintillator of low cost and of superior characteristics was found. The figure of merits better than 3.5 in rise time spectrum and the energy resolution better than 9% were obtained for carefully prepared samples. The background counting rate for a sample of 10 ml was reduced to 0.013 cpm/MeV in the range of alpha ray energy 5 to 7 MeV.

Alpha Particles↗
PubMed1984

[Low level alpha activity measurements with pulse shape discrimination--application to the determination of alpha-nuclides in environmental samples].

Liquid scintillation counting of alpha rays with pulse shape discrimination was applied to the analysis of 226Ra and 239+240Pu in environmental samples and of alpha-emitters in/on a filter paper. The instrument used in this study was either a specially designed detector or a commercial liquid scintillation counter with an automatic sample changer, both of which were connected to the pulse shape discrimination circuit. The background counting rate in alpha energy region of 5-7 MeV was 0.01 or 0.04 cpm/MeV, respectively. The figure of merit indicating the resolving power for alpha- and beta-particles in time spectrum was found to be 5.7 for the commercial liquid scintillation counter.

Alpha Particles↗
PubMed1984

[Agenesis of the corpus callosum associated with interhemispheric cyst. A case report].

A 7-year-old boy was admitted because of convulsive seizures. He was diagnosed as agenesis of corpus callosum associated with interhemispheric cyst by CT scan and angiography. Metrizamide CT cisternography and cystography disclosed no communication between interhemispheric cyst and the third ventricle. By means of metrizamide CT cisternography and cystography, the authors considered this interhemispheric cyst gradually increased by some kinds of ball-valve mechanism. Cysto-peritoneal shunt was carried out. Postoperative course was uneventful and follow-up CT revealed disappearance of interhemispheric cyst and typical findings of the acallosal brain. Improvement of clinical symptoms and EEG findings occurred after operation. Agenesis of the corpus callosum associated with interhemispheric cyst is rare. The authors can find only one case of this brain anomaly in the literature in which there is no communication between interhemispheric cyst and the third ventricle. Metrizamide CT cisternography and cystography was very useful in diagnosis and selection of treatment.

Brain Diseases↗
PubMed1983

Inhibition of agonist-induced degradation of muscarinic cholinergic receptor by quinacrine and tetracaine--possible involvement of phospholipase A2 in receptor degradation.

Muscarinic cholinergic receptors (mAChR) are degraded on the addition of agonists through energy- and temperature-dependent processes, probably with clustering and endocytosis. Pretreatment of guinea-pig vas deferens with 0.5 mM quinacrine or 5 mM tetracaine, phospholipase A2 (PLase A2) inhibitors, inhibited the ACh-induced degradation of mAChR in the smooth muscle and kept mAChR on the surface membrane, while cocaine and procaine were not effective. On pretreatment with quinacrine or tetracaine the PLase A2 activity in the smooth muscle decreased continuously during culture without change in the contractile response of the tissue. Pretreatment with cocaine and procaine which had no significant effect on the down regulation of mAChR did not inhibit PLase A2 activity. However, activation of PLase A2 by long-term culture of the muscle with ACh and formation of endogenous inhibitor of PLase A2 were not observed under our experimental conditions. The participation of PLase A2 in the agonist-induced degradation of mAChR is discussed in the light of these findings.

Anesthetics, Local↗
PubMed1983

Effect of urea-treatment on agonist binding affinity of the muscarinic acetylcholine receptor.

Urea-treatment of the microsome fraction of the heart of guinea-pigs caused selective reduction in the apparent affinity of an agonist (carbachol), but not an antagonist (atropine), to muscarinic acetylcholine receptors (mAChR), measured as inhibition of binding of 3H-quinuclidinyl benzilate (3H-QNB). This effect was similar to that of Gpp (NH)p. The effects of urea-treatment and Gpp (NH)p were not additive. On the other hand, treatment of the microsome fraction with 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) increased the apparent affinity of agonist, but not antagonist. The effect of DTNB predominated over those of urea-treatment and Gpp (NH)p, when these treatments were combined with DTNB.

Animals↗
PubMed1983

Highly sensitive method for determination of esterase activity of alpha-chymotrypsin and alpha-chymotrypsin-like enzymes using micro high-performance liquid chromatography.

A new substrate, Dns-L-phenylalanine ethyl ester, with high UV absorption has been developed for the determination of the esterase activity of alpha-chymotrypsin and alpha-chymotrypsin-like enzymes. The product, generated by the enzyme action, Dns-L-phenylalanine, was clearly separated from the ester substrate by micro reversed-phase high-performance liquid chromatography. The substrate was highly stable under the enzyme assay conditions used. As little as 0.15 ng of alpha-chymotrypsin and 1.49 ng of subtilisin BPN' could be detected when a long reaction time was employed. Hydrolyses of the substrate by alpha-chymotrypsin and alpha-chymotrypsin-like enzymes were blocked by specific inhibitors of the enzymes.

Chromatography, High Pressure Liquid↗