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S Kokubun

Publications and source records attributed to S Kokubun.

At least 73 records · Page 4Linked to original sources
PubMed1996

Effects of purinoceptor agonists on cytosolic Ca2+ concentration in swine tracheal smooth muscle cells in culture.

1. The effects of various purinoceptor agonists on intracellular Ca2+ concentration ([Ca2+]i) in swine tracheal smooth muscle cells in primary culture were examined to investigate the subtype of purinoceptors in these cells. 2. ATP (1 microM to 1 mM) concentration-dependently increased [Ca2+]i which was measured by monitoring the fluorescence signal of fura2. 3. alpha, beta-Me ATP at concentrations higher than 10 microM increased [ca2+]i in the presence of extracellular Ca2+. Responses to the drug were 12 +/- 5 and 61 +/- 4% of responses to ATP (100 microM) at 100 microM and 1 mM, respectively (n = 7). The response to 100 microM ATP was inhibited by 62% in the presence of 1 mM alpha, beta-Me ATP (n = 8), though the drug at concentrations lower than that did not affect the response to ATP. 4. ATP increased [Ca2+]i in the absence of extracellular Ca2+. The response to ATP in this condition was 40% of that in the presence of extracellular Ca2+ (n = 8). 5. Neither cibacron blue 3GA (10 microM) (n = 8) nor suramin (10 and 100 microM) (n = 10) affected the response to ATP (1 microM to 100 microM). 6. The rank order of potency in the absence of extracellular Ca2+ was UTP > ATP > adenosine 5'-o-(3-thiotriphosphate) > > ADP = alpha, beta-methylene adenosine 5'-triphosphate > 2-(methylthio)-adenosine 5'-(tetrahydrogen triphosphate). 7. UTP (1 microM to 100 microM) concentration-dependently increased inositol 1,4,5-triphosphate (IP3) production. 8. These results suggest that the increase in [Ca2+]i induced by purinoceptor agonists is mediated mainly via a nucleotide receptor in swine tracheal smooth muscle cells in primary culture.

Adenosine Triphosphate↗
PubMed1996

Extradural granulocytic sarcoma of the thoracic spine in acute myelogenous leukemia with 8; 21 chromosome translocation.

We report a case of a 19-year-old male with an extradural granulocytic sarcoma at T5/6 to T7 demonstrated by MRI. He recovered from paraplegia that had progressed rapidly after excision of the tumor as an emergency operation. Histopathological studies disclosed granulocytic sarcoma. Both peripheral blood and bone marrow examinations revealed acute myelogenous leukemia. The karyotype of the bone marrow showed 45, X, -Y, t (8; 21) (q22; q22).

Adult↗
PubMed1996

Hydroxyapatite crystals in tumoral calcinosis: a case report.

Calcified deposits of tumoral calcinosis from a 77-year-old Japanese woman were examined by scanning electron microscopy (SEM) and x-ray diffraction method. SEM revealed conglomerates of granular calcified materials 0.2 to 0.5 micron in size. X-ray diffraction method revealed the presence of hydroxyapatite that was highly crystallized. No other components such as calcium pyrophosphate dehydrate were detected.

Aged↗
PubMed1995

Glycosaminoglycans in intervertebral disc amyloid deposits.

Intervertebral discs are a common site of localized articular and some forms of systemic articular amyloid deposition. Whether there is an intrinsic matrix factor that favours amyloid deposition in intervertebral disc connective tissues is uncertain, but it is known that small localized deposits of amyloid in intervertebral discs are largely age related. As the glycosaminoglycans (GAGs) composition of the intervertebral disc is known to change with age, and as some forms of systemic amyloid deposition have been shown to be associated with particular highly sulphated GAGs, we examined the GAGs profile of amyloid deposits in intervertebral discs using mucin histochemistry (Alcian blue: MgCl2 critical electrolyte concentration) and immunohistochemistry. We found strong staining for very highly sulphated GAGs (0.9 M and 1 M MgCl2) and confirmed the presence of keratan sulphate in both localized and systemic, dialysis-associated beta 2-microglobulin amyloid deposits within disc fibrocartilage. These findings suggest that qualitative and quantitative changes in matrix GAGs, particularly strongly sulphated GAGs such as keratan sulphate, may play a role in the pathogenesis of localized and systemic amyloid deposition in intervertebral discs.

Adolescent↗
PubMed1995

Reduced expression of neurofibromin in the soft tissue tumours obtained from patients with neurofibromatosis type I.

1. We analysed the expression of neurofibromin mRNAs, encoded by the gene responsible for neurofibromatosis type 1, and of neurofibromin protein in nine soft tissue tumours by S1 nuclease mapping and Western blot analyses. Four tumours were obtained from patients with neurofibromatosis type 1, comprising two neurofibromas, one fibrolipoma and one malignant schwannoma, and five neurogenic tumours were obtained from non-neurofibromatosis type 1 patients. 2. All tumours, except for a malignant schwannoma, similarly expressed three species of mRNA encoding neurofibromin, an isoform with the insertion of 21 amino acids in the domain related to ras GTPase-activating protein, and an N-terminal isoform lacking this domain. 3. Western blot analysis demonstrated deficiency of neurofibromin in the tumours derived from three out of the four neurofibromatosis type 1 patients: a fibrolipoma, a malignant schwannoma and a neurofibroma. In contrast, reduction in neurofibromin was not detected in the five tumours obtained from non-neurofibromatosis type 1 patients. Furthermore, the expression of ras GTPase-activating protein was detected in all nine tumours examined. 4. The undetectable or reduced level of neurofibromin in the tumours obtained from neurofibromatosis type 1 patients suggests that this deficiency is closely related to their tumourigenesis.

Adult↗
PubMed1995

Contribution of P2-purinoceptors to neurogenic contraction of rat urinary bladder smooth muscle.

1. The contribution of P2-purinoceptors to neurogenic contraction was investigated in rat urinary bladder smooth muscle by measurement of isotonic tension. 2. Contraction of rat urinary bladder smooth muscle induced by electrical stimulation was decreased to 84.19 +/- 3.90% of the control (n = 16) in the presence of atropine (1 microM), which was further decreased to 38.80 +/- 2.75% of the control (n = 49) in the presence of both atropine and 10 microM alpha, beta-methylene adenosine 5'-triphosphate (alpha, beta-Me ATP). 3. The contractile response induced by electrical stimulation in the presence of atropine and alpha, beta-Me ATP was decreased to 27.81 +/- 4.07% (n = 23) and 26.63 +/- 5.01% (n = 15) of the control, by the addition of 100 microM cibacron blue 3GA and 100 microM suramin, respectively. The application of 100 microM adenosine 5'-o-2-thiodiphosphate (ADP beta S) in the presence of atropine and alpha, beta-Me ATP decreased the contractile response induced by electrical stimulations to 17.15 +/- 3.71% (n = 15) of the control. 4. Pretreatment of muscle strips with 100 microM ADP beta S significantly reduced the response to either 200 microM alpha, beta-methylene adenosine 5'-diphosphate or 200 microM ADP beta S. 5. Uridine 5'-triphosphate (100 microM to 1 mM) concentration-dependently contracted muscle strips, and this contraction was significantly antagonized by desensitization of P2-receptors with alpha, beta-Me ATP (10 microM), and completely antagonized by pretreatment of muscle strips with both alpha, beta-Me ATP and ADP beta S (100 microM). 6. Di(adenosine-5') tetraphosphate (30 and 100 microM) contracted muscle strips, whereas it failed to contract after desensitization of P2-receptors.7. It is suggested that about 20% of the neurogenic contraction of rat urinary bladder smooth muscle is mediated via ADP beta S-sensitive purinoceptors.

Acetylcholine↗
PubMed1995

[Matrix metalloproteinase (MMP-9) in patients with rheumatoid arthritis].

MMP-9 degrades type IV collagen, gelatin, type V collagen, and type XI collagen. We measured proMMP-9 and proMMP-9/TIMP-1 complex in sera and joint fluids by sandwich ELISA, and examined immunohistochemically the expression of these proteins in joint tissue from patients with rheumatoid arthritis (RA). ProMMP-9 was purified by the three chromatographic steps from the culture medium of HT1080 cells. Purified proMMP-9 and activated MMP-9 by APMA showed a single band of Mr92000, Mr67000, resectively on gelatin-zymography. We raised two monoclonal antibody colones 2G9, 8G7 against proMMP-9 with BALB/c mice. 2G9 and 8G7 reacted with proMMP-9 on Western blotting, and these clones reacted proMMP-9 and proMMP-9/TIMP-1 complex on sandwich ELISA, specifically. ProMMP-9 concentration in 86 sera (749.4+/-940.2 ng/ml) and 54 joint fluids (4539.9+/-7681.5 ng/ml) from patients with RA was significantly higher than those of patients with osteoarthritis and control. Immunohistochemistry with 2G9 showed that in rheumatoid synovium proMMP-9 localized in neutrophils and monocytes diffusely infiltrated the sublining layer. In addition, osteoclasts in rheumatoid subchondral bone were intensively stained. ProMMP-9 concentration in joint fluids from 39 RA patients was not correlated to stage and class of Steinbrocker and to clinical laboratorial data. But, it was positively correlated to the number of proMMP-9 positive cells in RA synovium (r=0.607) and the score of Roony's diffuse infiltrates of lymphocytes (r=0.720). Our results suggest a role of MMP-9 in joint destraction of RA throughout neutrophils and monocytes, and a regulation of this enzyme by lymphocytes.

Adult↗
PubMed1994

The effect of extracellular Ca2+ concentration on the negative staircase of Ca2+ transient in field-stimulated rat ventricular cells.

We performed experiments using the Ca2+ indicator dye, fura-2 to investigate the effect of extracellular Ca2+ concentration ([Ca2+]o) on sarcoplasmic reticulum (SR) Ca2+ release and loading in single rat ventricular cells. In normal Tyrode solution (1.8 mM [Ca2+]o) repetitive stimulation (0.5 Hz) resulted in a gradual decrease in calcium transients (the negative staircase phenomenon) without being accompanied by a gradual decrease in diastolic intracellular Ca2+ concentration. The rate of the slow decline in calcium transient was faster in lower [Ca2+]o. However, the peak of the first calcium transient was relatively invariant over a wide range of [Ca2+]o (0.5-5 mM). The size of the calcium transient elicited by field stimulation was proportional to that induced by 10 mM caffeine, applied following the field stimulation. These results suggest that the size of calcium transients depends mainly on the Ca2+ content of the SR. The quiescent period favoured the replenishment of the SR and this effect was promoted further by increasing the driving force for Ca2+ entry across the sarcolemma during this period. We conclude that in low [Ca2+]o, short stimulation interval may limit Ca2+ influx across the sarcolemma during the quiescent period to cause a gradual reduction in calcium content of the SR and thus the calcium transient.

4-Aminopyridine↗
PubMed1994

A region of the muscarinic-gated atrial K+ channel critical for activation by G protein beta gamma subunits.

Complementary DNAs encoding two types of inwardly rectifying K+ channels, GIRK1 and IRK1, have been cloned from rat atrium and mouse macrophage, respectively. GIRK1 expressed in Xenopus oocytes was activated by acetylcholine when m2 muscarinic acetylcholine receptor was coexpressed. The acetylcholine-induced activation of GIRK1 was enhanced by coexpression with the G protein beta 1 gamma 2 subunit but not the beta 1 gamma 1 or alpha subunits. Deletion of the C-terminus of GIRK1 impaired the channel activation associated with the beta 1 gamma 2 subunit. Moreover, replacement of the C-terminus of IRK1 with that of GIRK1 produced a chimera channel that was activated by the beta 1 gamma 2 subunit, whereas intact IRK1 was not activated by the beta 1 gamma 2 subunit. These findings define the C-terminus of GIRK1 as a regulatory region for the G protein beta gamma subunit.

Animals↗
PubMed1994

Prognosis of cervical spinal cord injury in correlation with magnetic resonance imaging.

Magnetic resonance (MR) images of 18 patients with a cervical spinal cord injury were analysed for prognostic signs of paralysis. Serial MR images were obtained within 48 hours (acute stage), then 2 weeks (subacute stage) and an average of 12 months (range 6-24 months) after injury. The patterns of signal intensity in the acute stage were divided into two types, slightly-low/low (SL/L) type and slightly-low/high (SL/H) type on T1-weighted images (T1WI) and T2-weighted images (T2WI). The patterns in the subacute stage were divided into two types, high/high (H/H) type and normal/high (N/H) type on T1WI and T2WI. Six patients showed SL/L type in the acute stage and H/H type in the subacute stage. Five of the patients had a paralysis of grade A and one of grade B at admission which remained unchanged after treatment. One patient showed SL/H type in the acute stage and H/H type in the subacute stage. The patient had a paralysis of grade A that improved to no more than grade B. The remaining 11 patients showed SL/H type in the acute stage and N/H type in the subacute stage. Their paralysis was from grade B to D at admission and grade D or E at the follow up. The signal intensity of SL/L type in the acute stage and H/H type in the subacute stage are bad prognostic signs.

Adolescent↗
PubMed1994

Subtypes of purinoceptors in rat and dog urinary bladder smooth muscles.

1. Both adenosine and adenosine 5'-triphosphate (ATP) (10 microM and 100 microM) relaxed 10 microM acetylcholine (ACh)-induced contraction of rat bladder strips, which was completely antagonized by 100 microM 8-(p-sulphophenyl) theophylline. In dog bladder neither adenosine nor ATP inhibited ACh-induced contraction. 2. P2x-purinoceptor agonists contracted both rat and dog bladder strips with the potency order of alpha,beta-MeATP > ATP > ADP. 3. Alpha,beta-MeADP (100 microM) induced a contraction of the rat bladder strip even after desensitization of P2x-purinoceptors but failed to contract the dog bladder strip. 4. 2-MeSATP (1 microM to 300 microM) concentration-dependently induced contraction of rat bladder strips; this contraction was significantly inhibited after desensitization of P2x-purinoceptors. Cibacron blue 3GA (100 microM) antagonized the drug at concentrations lower than 30 microM, whereas it augmented the response to the drug at concentrations above 30 microM. 5. ADP beta S (1 microM to 1 mM) concentration-dependently induced contraction of rat bladder strips after desensitization of P2x-purinoceptors; a contraction which was significantly antagonized by cibacron blue 3GA (100 microM). 6. It is concluded that three subtypes of purinoceptors, P1 (mediating relaxation), and P2x and another type of P2 (mediating contraction), exist in rat urinary bladder smooth muscle, whereas a single subtype of the receptor, P2x-purinoceptor (mediating contraction) occurs in dog urinary bladder smooth muscle.

Acetylcholine↗
PubMed1994

Histological verification of bone bonding and ingrowth into porous hydroxyapatite spinous process spacer for cervical laminoplasty.

Three spinous processes of the cervical spine and implanted porous hydroxyapatite spacers were removed from a patient with a recurring intramedullary tumor at revisional laminectomy one year after spinous process splitting laminoplasty. Histological examination of undecalcified sections revealed direct bone bonding to the spacer at three of the six bone-hydroxyapatite interfaces. Bone ingrowth was observed up to 400 microns into the implant pores. Fibrous tissue was observed to intervene between the other three bone-hydroxyapatite interfaces. The suspected bone bonding with the spacer on CT scans before the revision was confirmed by the histological findings.

Astrocytoma↗
PubMed1993

One-stage anterior and posterior correction of severe kyphosis of the cervical spine in neurofibromatosis. A case report.

A case is presented of a 29-year-old woman with neurofibromatosis, who had a 100 degrees dystrophic kyphosis of the cervical spine and was successfully treated by a one-stage anterior and posterior correction. Anterior distractive and posterior compressive corrections were simultaneously applied keeping the posterior longitudinal ligament intact. The kyphosis was corrected to 42 degrees. Safety and better results of the one-stage correction of kyphosis is based on a concept of shortening the spinal canal.

Adult↗
PubMed1992

Cyclic AMP-dependent phosphorylation and regulation of the cardiac dihydropyridine-sensitive Ca channel.

A polyclonal antibody, CR2, prepared using the C-terminal peptide of the alpha 1 subunit of the rabbit cardiac DHP-sensitive Ca channel, specifically immunoprecipitated the [3H]PN200-110-labeled Ca channel solubilized from cardiac microsomes. The antibody recognized 250 and 200-kDa cardiac microsomal proteins as determined by immunoblotting, and cAMP-dependent protein kinase phosphorylated the 250-kDa, but not the 200-kDa protein in vitro. CHO cells, transfected with the cardiac alpha 1 subunit cDNA carried by an expression vector, synthesized a 250-kDa protein which was recognized by CR2. Adding db-cAMP or forskolin to the transformed CHO cells induced phosphorylation of the 250-kDa protein and stimulated the DHP-sensitive Ba current under patch-clamp conditions. These results suggested that the cardiac DHP-sensitive Ca channel was regulated by cAMP-dependent phosphorylation of the alpha 1 subunit.

Animals↗
PubMed1991

Mechanisms underlying the slow onset of action of a new dihydropyridine, NZ-105, on a cultured smooth muscle cell line.

The inhibitory effect of a new dihydropyridine derivative, (+/-)-2-[benzyl(phenyl)amino]ethyl-1,4-dihydro-2,6-dimethyl-5- (5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl )-3- pyridinecarboxylate hydrochloride (NZ-105), on whole cell Ca2+ current (ICa) in cultured vascular smooth muscle cells was investigated with the patch clamp technique. NZ-105 blocked ICa in a concentration-dependent manner when the command pulse ranged from +10 mV to -50 mV. The inhibitory effect of NZ-105 appeared at concentrations higher than 10 pmol/l and it blocked ICa completely at a concentration of 1 nmol/l. The concentration which produced the half-maximal inhibitory effect was estimated to be around 20 pmol/l. NZ-105 (500 pmol/l) completely blocked ICa elicited by depolarization to +10 mV at a holding potential of -40 mV, whereas it blocked ICa by only 67% at a holding potential of -90 mV. NZ-105 (100 pmol/l) shifted the steady-state inactivation curve by 40 mV to more negative potentials without affecting its slope factor. The blocking time constant of 500 pmol/l NZ-105 was 57.6 +/- 9.9 s at a holding potential of -70 mV. These results indicate that NZ-105 has characteristics typical of dihydropyridines and binds to Ca2+ channels of vascular smooth muscle cells with a high affinity. They also suggested that the slow onset of its action is due to the slow binding of the drug to Ca2+ channels.

Animals↗