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Biomedical subjects

S Kokubun

Publications and source records attributed to S Kokubun.

At least 37 records · Page 2Linked to original sources
PubMed2001

Calcium waves in skinned cardiac myocytes evoked by two-photon excitation photolysis of caged calcium.

In rat ventricular myocytes chemically skinned with saponin, a local rise of [Ca2+] was achieved by two-photon excitation photolysis (TPP) of the caged Ca2+ compound 1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N',N'-tetrakis[(oxycarbonyl)methyl]-1,2-ethanediamine (DM-nitrophen). Confocal Ca2+ images, by use of fluo-3, were simultaneously collected. TPP of DM-nitrophen induced Ca2+ waves propagating over the myocyte, and the local rise of [Ca2+] at the site of photolysis sustained for 50-60 ms. These TPP-induced Ca2+ events were completely suppressed by ryanodine (10 microM), suggesting that Ca2+ release resulting from TPP of DM-nitrophen triggered regenerative Ca2+ release from the neighboring sarcoplasmic reticulum. The present techniques should be useful to investigate the interaction of elementary Ca2+ events, the process leading to global Ca2+ movements, in cardiac myocytes and other types of cells.

Animals↗
PubMed2001

Extraskeletal osteosarcoma arising in the buttock.

Extraskeletal osteosarcoma is a rare sarcoma that accounts for about 1% of malignant soft tissue tumours. We report an very unusual case of a small-size extraskeletal osteosarcoma arising in the superficial subcutaneous region of the buttock. The patient was a 55 year-old female. She incidentally noticed a small nodule in the right trochanteric region. It was removed under local anesthesia at a private clinic. An additional wide excision was performed at our hospital. There was an 8 mm? 10 mm mass in the subcutaneous tissue. No invasion of the underlying fascia was observed. Microscopic examination of the removed tumour showed bizarre-looking spindle and giant cells with lace-like osteoid. The tumour was diagnosed as extraskeletal osteosarcoma. Chemotherapy with Rosen T-20 was administered to the patient. The patient has survived without recurrence or metastasis for 4 years since the primary surgery. Its superficial location, very small size, wide excision, and chemotherapy were thought to contribute to her long survival.

Buttocks↗
PubMed2001

Comparison of spinal cord gray matter and white matter softness: measurement by pipette aspiration method.

OBJECT: Although the gray matter of the spinal cord has been thought to be softer than the white matter, there is no evidence to support this belief. Because the spinal cord is extremely soft, it has been difficult to measure the mechanical properties of the gray and white matter. The modulis of elasticity of the gray and white matter were measured in situ by using a pipette aspiration method. METHOD: The spinal cord specimens were excised from Japanese white rabbits. Specimens were cut to display the surfaces of axial, frontal, and sagittal sections. The surfaces of the gray and white matter were aspirated using a 0.8-mm-inner-diameter glass pipette while monitoring with a video microscope, and the deformed length in the pipette was measured on a monitor. In each case the modulus of elasticity was calculated by comparing the relationship between the aspiration pressure and aspirated volume of the specimen with that determined by finite element analysis. The moduli of elasticity of the gray and white matter were 3.4+/-1.4 kPa (mean +/- standard deviation) and 3.4+/-0.9 kPa in the axial section, 3+/-0.3 kPa and 3.5+/-0.5 kPa in the frontal section, and 3.5+/-0.9 kPa and 2.8+/-0.4 kPa in the sagittal section, respectively. CONCLUSIONS: No significant difference in modulus of elasticity was shown between the gray and white matter of the spinal in sections made in various directions.

Animals↗
PubMed2001

[Expression of urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR) plays a role in destruction of joint tissue in rapidly destructive coxarthropathy (RDC)].

OBJECTIVE: Proliferation of small vessels including capillaries in joint tissues is one of the significant histopathological features of rapidly destructive coxarthropathy (RDC). To examine the relationship between the angiogenesis and bone destruction, expression of urokinase-type plasminogen activator (uPA) and uPA receptor (uPAR), which are necessary for angiogenesis was histochemically investigated. MATERIALS AND METHODS: Synovia and cartilage-bone tissues of femoral head were obtained from RDC patients at total hip replacement (THR). These joint tissues were fixed with 4% paraformaldehyde, and cartilage-bone tissues were decalcified, additionally. Immunohistochemical staining was performed on paraffin sections, using monoclonal antibodies against human uPA and uPAR. RESULT: There was a difference between expression of uPA and that of uPAR. Expression of uPA was observed in many types of cells such as osteoclasts, giant cells, fibroblast-like cells and macrophages, of which osteoclasts and giant cells were most prominent. On the other hand, expression of uPAR was detected mainly in fibroblast-like cells and macrophages and rarely seen in osteoclasts and giant cells. CONCLUSION: These results indicate that uPA-plasmin system contributes to bone destruction in RDC, and furthermore, that fibroblast-like cells and macrophages play an important role in activation of uPA-plasmin system.

Aged↗
PubMed2000

A region of the sulfonylurea receptor critical for a modulation of ATP-sensitive K(+) channels by G-protein betagamma-subunits.

To determine the interaction site(s) of ATP-sensitive K(+) (K(ATP)) channels for G-proteins, sulfonylurea receptor (SUR2A or SUR1) and pore-forming (Kir6.2) subunits were reconstituted in the mammalian cell line, COS-7. Intracellular application of the G-protein betagamma2-subunits (G(betagamma)(2)) caused a reduction of ATP-induced inhibition of Kir6.2/SUR channel activities by lessening the ATP sensitivity of the channels. G(betagamma)(2) bound in vitro to both intracellular (loop-NBD) and C-terminal segments of SUR2A, each containing a nucleotide-binding domain (NBD). Furthermore, a single amino acid substitution in the loop-NBD of SUR (Arg656Ala in SUR2A or Arg665Ala in SUR1) abolished the G(betagamma)(2)-dependent alteration of the channel activities. These findings provide evidence that G(betagamma) modulates K(ATP) channels through a direct interaction with the loop-NBD of SUR.

ATP-Binding Cassette Transporters↗
PubMed2000

Extended magnetic reconnection at the Earth's magnetopause from detection of bi-directional jets

Magnetic reconnection is a process that converts magnetic energy into bi-directional plasma jets; it is believed to be the dominant process by which solar-wind energy enters the Earth's magnetosphere. This energy is subsequently dissipated by magnetic storms and aurorae. Previous single-spacecraft observations revealed only single jets at the magnetopause--while the existence of a counter-streaming jet was implicitly assumed, no experimental confirmation was available. Here we report in situ two-spacecraft observations of bi-directional jets at the magnetopause, finding evidence for a stable and extended reconnection line; the latter implies substantial entry of the solar wind into the magnetosphere. We conclude that reconnection is determined by large-scale interactions between the solar wind and the magnetosphere, rather than by local conditions at the magnetopause.

Journal Article↗
PubMed2000

Changes with age in proteoglycan synthesis in cells cultured in vitro from the inner and outer rabbit annulus fibrosus. Responses to interleukin-1 and interleukin-1 receptor antagonist protein.

STUDY DESIGN: Proteoglycan synthesis was examined in cells isolated from the inner and outer annulus fibrosus of young and old rabbits. Their responses to interleukin-1 alpha and interleukin-1 receptor antagonist protein were investigated. OBJECTIVES: To evaluate the age-related changes and the anatomically related differences in the function of intervertebral disc cells. SUMMARY OF BACKGROUND DATA: Proteoglycan content in the human intervertebral disc decreases with age. Age-related changes in intervertebral disc cell function, however, have not been fully investigated. METHODS: Japanese white rabbits aged 2 months (young group) and 3 years (old group) were used. The inner and outer layer of the annulus fibrosus were separated. The proteoglycan synthesis and release were measured in cells cultured with or without human recombinant interleukin-1 alpha and interleukin-1 receptor antagonist protein. RESULTS: The proteoglycan synthesis significantly decreased and the release rate significantly increased in the old rabbits, compared with the young ones. In the inner annulus, the inhibition of proteoglycan synthesis due to interleukin-1 alpha was greater in the old rabbits than in the young ones. In the old rabbits, interleukin-1-induced inhibition was more pronounced in the inner annulus than in the outer annulus. Interleukin-1 receptor antagonist protein suppressed inhibition of proteoglycan synthesis by interleukin-1 alpha in the two layers in both age groups. CONCLUSIONS: Both the decline in proteoglycan synthesis and the increased cell sensitivity to interleukin-1 alpha with age may contribute to the degradation of discs. The increase in cell response to interleukin-1 alpha in the inner annulus of rabbits may explain why the inner annulus and nucleus pulposus degrade earlier than the outer annulus in human discs. Interleukin-1 receptor antagonist protein could be useful in inhibiting the degradation of the disc.

Age Factors↗
PubMed2000

Multiple epiphyseal dysplasia--report of two families.

Multiple epiphyseal dysplasia (MED) is a relatively uncommon inherited disorder of epiphyseal maturation. Affected individuals may have a degree of short-limbed dwarfism, short stubby digits, and stiff or painful joints. We report two families of MED and emphasize the variations of joint involvement. Ten out of 34 members in family A and 13 out of 39 members in family B were suspected of having MED by questionnaire. Radiological examination was done for 3 out of the 10 members in family A and 6 out of the 13 members in family B. In both families, the epiphyseal disturbances in the skeleton were bilaterally symmetric and involved several joints. Apparent dwarfism, short stubby digits and spinal involvement were not observed. The degree and the pattern of affected joints were different in the two families and even among members of the same family. In family A, the knee joint was commonly affected, followed by the ankle joint. The deformity of the joints was mild and caused only slight disability. No apparent hip lesion was present. In family B, the hip joint was predominantly affected, followed by the knee and ankle joints, and the deformity was severer than that in family A. These observations suggest that MED is a group of heterogeneous disorders.

Adult↗
PubMed2000

Enhanced neutrophilic granulopoiesis in rheumatoid arthritis. Involvement of neutrophils in disease progression.

OBJECTIVE: To investigate enhanced granulopoiesis in bone marrow of patients with rheumatoid arthritis (RA), and the role of neutrophils in RA pathogenesis. METHODS: Aspirated bone marrow cells and peripheral blood leukocytes from patients with RA and non-RA patient controls were analyzed morphologically and by 2 color flow cytometry. Thirteen iliac bones (8 RA, 5 non-RA) were examined by light and transmission electron microscope (TEM). RESULTS: The percentage of CD15+CD16- cells (immature neutrophils) in RA bone marrow (64.3+/-13.4%, mean +/- SD) increased significantly compared to that of non-RA controls (43.2+/-14.3%), whereas the fraction of CD15+CD]6+ cells (mature neutrophils)was greatly decreased (RA 21.8+/-10.1%; non-RA 38.1+/-8.9%). The absolute number of CD15+CD16- cells also increased markedly in RA bone marrow. The ratio of immature cells to the total granulocytes (% CD15+CD16- to % CD15+) correlated with the Lansbury Index score (R = 0.76, p<0.0001). TEM observations revealed that abundant immature neutrophils adhered closely to the trabeculae of the iliac bone. Margins of trabeculae were mostly irregular, especially in severe RA, and collagenous fibers frequently disappeared in those trabeculae with ragged margins. CONCLUSION: In RA bone marrow, immature neutrophils (CD15+CD16-) were markedly increased in number; by contrast, no changes were found for mature cells. Augmented production of immature neutrophils (at the promyelocyte-to-myelocyte stage) might lead to the destruction of collagenous fibers in RA bone trabeculae, as revealed by TEM. Generalized bone destruction in RA might, at least in part, be caused by enhanced production of immature neutrophils.

Adult↗
PubMed2000

Pharmacokinetic study of theophylline in dogs after intravenous administration with and without ethylenediamine.

Aminophylline (ethylenediamine salt of theophylline) and Theodrip, a new formulation of theophylline developed by Nikken Chemicals, are drugs for the treatment of acute bronchial asthma in injectable form. The present study was conducted using dogs to first confirm the bioequivalence of the two injectable forms containing theophylline and aminophylline and to secondly clarify the influence of the rate of venous infusion on the pharmacokinetics of theophylline in plasma. The following results were obtained: 1) Pharmacokinetic parameters of plasma theophylline after an intravenous bolus injection were close to those after the dosing of aminophylline in dogs by a crossover method. Thus, the 95% confidence limits of mean value differences of Cmax, t1/2 and AUC between the two injection forms were in the range of -3.16-4.28%, -6.19-7.28% and -7.23-5.28%, respectively. These results indicate the bioequivalence between theophylline and aminophylline in dogs from a pharmacokinetic point of view as well as the lack of influence of ethylenediamine on the pharmacokinetics of theophylline. 2) After the intravenous bolus injection (30 sec) and the 15-min constant rate infusion of theophylline to dogs, the plasma concentrations of theophylline were 27.37 +/- 3.67 micrograms/ml and 18.34 +/- 2.32 micrograms/ml immediately after the completion of administration, respectively. It is notable that in humans the former concentration level has been observed to frequently cause adverse effects, whereas the latter was in the safe range. Consequently, the 15-min constant rate infusion did not result in the rapid increase in the plasma theophylline concentrations and was superior to the bolus injection from the viewpoint of maintaining the safety plasma concentrations. In conclusion, to avoid hypersensitivity due to ethylenediamine and the adverse effects caused by high plasma concentrations of theophylline, it was considered that constant rate infusion of theophylline to the venous is preferable in the clinical setting.

Aminophylline↗
PubMed1999

Enhanced beta-receptor-mediated vasorelaxation in hypoxic porcine coronary artery.

To investigate the beta-adrenoceptor-mediated responses in hypoxic coronary arteries, we studied the effect of isoproterenol (Iso) on isolated porcine coronary arteries contracted with endothelin-1 in media aerated with 0, 5, 7.5, and 95% O(2). The concentration-response curve of Iso was significantly shifted to the left by hypoxia (0 and 5% O(2)). In oxygenated and hypoxic arteries, 3 x 10(-8), 10(-6), and 10(-5) M Iso significantly increased the contents of cAMP. However, there was no difference in the increases of cAMP content induced by 3 x 10(-8) M Iso between oxygenated and hypoxic arteries. The content of cAMP induced by high concentrations of Iso (10(-6) and 10(-5) M) was significantly larger in hypoxic than in oxygenated arteries. Furthermore, the potentiation by hypoxia of the Iso-induced vasorelaxation was inhibited by glibenclamide and depolarization by KCl, but not by removal of endothelium and indomethacin. The vasodilatory response to forskolin and dibutyryl cAMP was unaffected by hypoxia. We conclude that activation of the ATP-sensitive K(+) channel may account for the potentiation of the response to Iso in hypoxic coronary arteries.

Animals↗
PubMed1999

Clinical use of etodolac for the treatment of lumbar disc herniation.

This paper reports a non-comparative multicentre study designed to assess the usefulness of a non-steroidal anti-inflammatory agent--etodolac--for the treatment of lumbar disc herniation. The efficacy and safety of etodolac were evaluated based on the changes of symptoms and signs of the patients, including the following parameters: low back pain, leg pain and tingling, gait, the straight-leg-raising test, sensory disturbance, motor disturbance, restriction of activities of daily living (ADL), urinary bladder function, and patients' impressions at each hospital on the initial day, and at one week and two weeks after the start of administration of etodolac, in a total of 88 patients. The overall improvement was noted as a 'marked' in 5% and 13%, 'moderate' or better in 31% and 54%, 'slight' or better in 82% and 84%, 'no change' in 12% and 9%, and 'aggravated' in 6% and 7%, at one and two weeks after administration, respectively. The only adverse drug reaction reported was stomach pain in one of the 81 patients. It can be concluded that etodolac is an effective and well-tolerated non-steroidal anti-inflammatory agent in the treatment of lumbar disc herniation.

Activities of Daily Living↗
PubMed1999

c-Myc protein in the rabbit growth plate. Changes in immunolocalisation with age and possible roles from proliferation to apoptosis.

Growth plates taken from five- to 20-week-old Japanese white rabbits were immunostained for c-Myc protein. This was localised both in the proliferating zone and upper hypertrophic zone at five weeks, whereas after ten weeks it was found mostly in the lower hypertrophic zone. The proliferating chondrocytes tended to show nuclear staining and the hypertrophic cells cytoplasmic staining, although the terminal hypertrophic chondrocytes sometimes expressed the protein in their nuclei. In the younger rabbits, c-Myc co-localised with proliferating cell nuclear antigen, whereas in the hypertrophic zone of older rabbits, it was present in some chondrocytes the nuclei of which also contained DNA breaks. Our study suggests that, in the rabbit growth plate, c-Myc is associated with different cellular processes, depending on the age and the developmental stage of the chondrocytes.

Aging↗
PubMed1999

Localization of PDK-1 mRNA in the brain of developing and adult rats.

Gene expression for 3-phosphoinositide-dependent protein kinase-1 (PDK-1) in developing and adult rat brains was examined by in situ hybridization histochemistry. In embryonic days, the mRNA was evident throughout the entire neuraxis. The expression remained evident throughout the entire gray matters until postnatal day 7, and thereafter it decreased overall in the mantle and ventricular zones except for the cerebellar Purkinje and granule cell layers, the olfactory and hippocampal neuronal layers. The pattern of this gene expression is similar to those of for protein kinase B and class I phosphoinositide 3-kinases.

3-Phosphoinositide-Dependent Protein Kinases↗
PubMed1999

Fibrous dysplasia arising from the calcaneus.

A case of an 18-year-old woman with fibrous dysplasia arising in the calcaneus, which is extremely rare, is reported, with the emphasis placed on differential diagnosis from low-grade central osteosarcoma. She had a severe pain in her left ankle after sprain. Plain radiographs showed a radiolucent lesion measuring 6.3 x 2.5 cm with a sclerotic margin in the left calcaneus. CT scans showed a well-defined lytic lesion with disruption of the lateral cortex and an ossification or calcification in its center. On MR imaging, the lesion had isointensities and high intensities on T1 and T2 weighted images, respectively, but its central portions showed lower intensities both on T1 and T2 weighted images. The lesion was enhanced with gadolinium except for the central portions. The specimen obtained by open biopsy consisted of fibrous tissue and foci of irregular woven bone. None of the nuclear atypia, mitoses, longitudinal stream of bone or invasive nature of growth was detected. The diagnosis of fibrous dysplasia was histologically made. The lesion was curetted and packed with autogenous bone chips. No evidence of recurrence was noted postoperatively.

Adolescent↗
PubMed1999

Nonselective cationic currents activated by acetylcholine in swine tracheal smooth muscle cells.

Membrane currents in isolated swine tracheal smooth muscle cells were investigated using a pipette solution containing BAPTA-Ca2+ buffer and Cs+ as the major cation. With a pipette solution containing 100 nM free Ca2+, acetylcholine (ACh; 1-100 microM), in a concentration-dependent manner, activated a current without inducing shortening of cells, although neither 1 mM histamine nor 1 microM leukotriene D4 activated the current (n = 7, n is the number of cells). The effect of 100 microM ACh was suppressed by pretreatment with 100 microM atropine (n = 6) or intracellular application of preactivated pertussis toxin at a concentration of 0.1 microg x mL(-1) (n = 8). Genistein (0.1-100 microM), in a concentration-dependent manner, suppressed the activation of the inward current by 100 microM ACh, whereas it did not significantly suppress that of the outward current (n = 6-8). With a pipette solution containing 50 nM free Ca2+, outward current, but not inward current, was activated by 100 microM ACh (n = 10). When the pipette solution had free Ca2+ concentrations greater than 50 nM, the inward current together with the outward current was activated. The ratio between the amplitude of the inward and outward currents was significantly increased as the free Ca2+ concentration in the pipette solution increased. The steady-state activation curve of the ACh-activated current with the 50 nM free Ca2+ pipette solution was fitted by a single Boltzmann distribution (Vh = +69.8 mV, k = -11.9 mV, n = 10). The activation time constant became smaller as the membrane potential was more depolarized (164.3+/-5.9 ms at +40 mV to 92.4+/-6.3 ms at +120 mV, n = 10). The reversal potential was not significantly changed by reducing extracellular Cl- concentration to one-tenth of the control (n = 8), suggesting that the current is a nonselective cationic current. These results suggest that ACh activates an outward nonselective cationic current via pertussis toxin-sensitive G-protein(s) coupled with muscarinic receptors. Involvement of genistein-sensitive tyrosine kinase in the activation process of the current is unlikely.

Acetylcholine↗