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Biomedical subjects

C Kimura

Publications and source records attributed to C Kimura.

At least 19 recordsLinked to original sources

Two cases of atypical membranous aplasia cutis with hair collar sign: one with dermal melanocytosis, and the other with naevus flammeus.

We report two atypical cases of membranous aplasia cutis surrounded by a rim of hairs, one case associated with dense dermal melanocytosis and the other with naevus flammeus, with characteristic clinical features. A rim of hypertrichosis, 'hair collar' sign, is proposed to have a close association with neuroectodermal defects. A failure of the normal closure of the cranial neural tube might have affected foetal skin development, including melanoblast migration and capillary network formation. The changes in the present cases, as well as the hair collar sign may suggest a complex hamartomatous nature of membranous aplasia cutis.

Ectodermal Dysplasia↗

[Mediastinal mature teratoma perforating into the lung with elevated serum carbohydrate antigen 19-9 (CA19-9) levels; report of a case].

A 17-year-old woman was suddenly seized with anterior chest pain and admitted to our hospital. Chest X-ray, computed tomography (CT) scan and magnetic resonance imaging (MRI) showed a mass shadow in the left middle lung field associated with the left pleural effusion and high serum carbohydrate antigen 19-9 (CA 19-9) levels (58.5 U/ml). We performed a total resection of the tumor with adherent parts of the left lung. The tumor was 6.5 x 3. 8 x 2.9 cm in size, and was made up of soft tissues, fluid and cystic components. The histological diagnosis was a mature cystic teratoma with perforation into the lung, which contained pancreatic tissues, hepatic cells, bronchial epithelium, serous glands and so on. The levels of fluid amylase and CA 19-9 were high. We report mediastinal mature teratoma perforating into the lung and discuss the mechanism of perforation.

Adolescent↗

[Successful surgical treatment in a nonagenarian with aortic arch aneurysm].

Surgical treatment in a nonagenarian with thoracic aortic aneurysm is challenging, and the surgical indication in such patients is controversial. A 92-year-old female patient with severe chest and back pain was transferred to our hospital because of impending rupture of an aortic arch aneurysm with normal mental activity. Physical and laboratory examinations were within normal limits. The patients underwent urgent graft replacement of the total aortic arch. Postoperative course was uneventful and the patient remains well with no disability 8 months after the operation.

Aged↗

Complementary functions of Otx2 and Cripto in initial patterning of mouse epiblast.

The development of the mammalian antero-posterior (A-P) axis is proposed to be established by distinct anterior and posterior signaling centers, anterior visceral endoderm and primitive streak, respectively. Knock-out studies in mice have shown that Otx2 and Cripto have crucial roles in the generation and/or functions of these anterior and posterior centers, respectively. In both Otx2 and Cripto single mutants, the initial formation of the A-P axis takes place in a proximal-distal (P-D) orientation, but subsequent axis rotation fails to occur. To examine the developmental consequences of the lack of these two genes, we have analyzed the Otx2(-/-);Cripto(-/-) double homozygous mutant phenotype. In the double mutants, the expression of the A-P axis markers Cer-l, Lim1, and Wnt3 was not induced, while expression of Fgf8 and T was expanded throughout the epiblast, indicating that the double mutants could not form the A-P axis even in its initial P-D orientation. In addition, the double mutants displayed defects in differentiation of the visceral endoderm overlying the epiblast, as well as in the extraembryonic ectoderm. Furthermore, differentiation of neuroectoderm was accelerated as judged by the reduction of Oct4 expression and emergence of Sox1 and Gbx2 expression in the double mutant epiblast. The resulting ectoderm only displayed characteristics of anterior hindbrain, implicating it as a ground state in the mammalian body plan. Our results indicate that complementary functions of Otx2 and Cripto are essential for initial patterning of the A-P axis in the mouse embryo.

Animals↗

Amelioration of insulin resistance in diabetic ob/ob mice by a new type of orally active insulin-mimetic vanadyl complex: bis(1-oxy-2-pyridinethiolato)oxovanadium(IV) with VO(S(2)O(2)) coordination mode.

Recently, we have shown that a newly synthesized vanadyl complex, bis(1-oxy-2-pyridinethiolato)oxovanadium(IV), VO(opt)(2), is a potent orally active insulin-mimetic in treating streptozotocin-induced diabetes in rats, with long-term action. In the present study, the anti-diabetic effect of VO(opt)(2) and its mechanism in ob/ob mice, an obese non-insulin-dependent diabetes mellitus (NIDDM) animal model, was investigated. In ob/ob mice, 15-day oral treatment with VO(opt)(2) resulted in a dose-dependent decrease in the levels of glucose, insulin and triglyceride in blood. VO(opt)(2) was also effective in ameliorating impaired glucose tolerance in ob/ob mice, when an oral glucose tolerance test was performed after treatment with VO(opt)(2). Tumor necrosis factor-alpha (TNF-alpha) is a key component of obesity-diabetes link, we therefore examined the attenuating effect of VO(opt)(2) on impaired insulin signal transduction induced by TNF-alpha. Elevated expression of TNF-alpha was observed in the epididymal and subcutaneous fat tissues of ob/ob mice. Incubation of 3T3-L1, mouse adipocytes, with TNF-alpha reduced the phosphorylation of insulin receptor substrate-1 (IRS-1), whereas VO(opt)(2) treatment resulted in an enhancement of IRS-1 phosphorylation, irrespective of the presence or absence of TNF-alpha. Overall, the present study demonstrates that VO(opt)(2) exerts an anti-diabetic effect in ob/ob mice by ameliorating impaired glucose tolerance, and furthermore, attenuates the TNF-alpha-induced decrease in IRS-1 phosphorylation in adipocytes. These results suggest that the anti-diabetic action of VO(opt)(2) is derived from an attenuation of a TNF-alpha induced impaired insulin signal transduction via inhibition of protein tyrosine phosphatase, providing a potential clinical utility for VO(opt)(2) in the treatment of NIDDM.

3T3 Cells↗

Prevention of secondary osteoporosis postmenopause in hemiplegia.

OBJECTIVES: To study secondary osteoporosis postmenopause in women with hemiplegia and to show the therapeutic effects of etidronate and how osteoporotic conditions relate to the activities of daily living (ADL). DESIGN: Eighty-one postmenopausal women with hemiplegia were admitted within 6 mo of their first cerebrovascular accident. The bone mineral density (BMD) and biochemical markers of bone turnover were measured at the time of admission. Forty women (treatment group) received a 2-wk administration of etidronate. Forty-one women (control group) were not administered etidronate. RESULTS: After completing a 3-mo rehabilitation program, BMD levels were remeasured. ADL was evaluated by FIM. The low ADL group had a larger decrease in BMD than the high ADL group. For the control group, the BMD rate of change on the paretic side of the femoral neck was -9.6%/3 mo for the low ADL group. BMD loss was reduced significantly by the administration of etidronate for the low ADL group. CONCLUSIONS: Results indicate that ADL corresponds to the progression of osteoporosis in postmenopausal women with hemiplegia and that increasing the level of ADL will reduce the progression of osteoporosis. Use of etidronate has also been proven to have a suppressive effect on the BMD decrease in women.

Absorptiometry, Photon↗

A case of pedunculated malignant melanoma of the vaginal mucosa.

We report an 84-year-old Japanese woman who presented with a pedunculated malignant melanoma of the vaginal mucosa. Mucosal melanoma is believed to be more common in Japan than other countries, but such tumors of the vulvovaginal region are quite unusual. In our patient, three tumors were connected by a narrow pedicle. Three black tumors measuring 5-10 mm in diameter with a common pedicle were seen on the vaginal mucosa at five o'clock from the cervix. The tumors were hanging from the narrow pedicle. On histologic examination, they were diagnosed as malignant melanoma. Resection was done with a distal margin of 3 cm from the tumors and a margin of 1 cm from the cervix. The patient has had no evidence of local recurrence or distant metastasis. In our patient, the three main tumors had a common pedicle, which seems to be a unique finding. Since pedunculated malignant melanomas are rare, making a clinical diagnosis is difficult. Although pedunculated melanomas are recognized as having a high malignant potential because these lesions are generally thick, a relatively good outcome is sometimes reported. In our patient, there was no tumor infiltration into the dermis of the pedicle, and this may be one reason for the good outcome at present. There has been no previous report of a mucosal melanoma consisting of three tumors like those in the present patient.

Aged↗

Impairment of endothelial nitric oxide production by acute glucose overload.

We examined the effects of acute glucose overload (pretreatment for 3 h with 23 mM D-glucose) on the cellular productivity of nitric oxide (NO) in bovine aortic endothelial cells (BAEC). We had previously reported (Kimura C, Oike M, and Ito Y. Circ Res, 82: 677-685, 1998) that glucose overload impairs Ca(2+) mobilization due to an accumulation of superoxide anions (O(2)(-)) in BAEC. In control cells, ATP induced an increase in NO production, assessed by diaminofluorescein 2 (DAF-2), an NO-sensitive fluorescent dye, mainly due to Ca(2+) entry. In contrast, ATP-induced increase in DAF-2 fluorescence was impaired by glucose overload, which was restored by superoxide dismutase, but not by catalase or deferoxamine. Furthermore, pyrogallol, an O(2)(-) donor, also attenuated ATP-induced increase in DAF-2 fluorescence. In contrast, a nonspecific intracellular Ca(2+) concentration increase induced by the Ca(2+) ionophore A-23187, which depletes the intracellular store sites, elevated DAF-2 fluorescence in both control and high D-glucose-treated cells in Ca(2+)-free solution. These results indicate that glucose overload impairs NO production by the O(2)(-)-mediated attenuation of Ca(2+) entry.

Adenosine Triphosphate↗

Alterations of Ca2+ mobilizing properties in migrating endothelial cells.

Endothelial migration is one of the major events of pathological neovascularization. We compared the characteristics of Ca2+ mobilization in nonconfluent, confluent, and migrating endothelial cells. Migration of endothelial cells was induced by wounding the confluent cell monolayer. The basal intracellular Ca2+ concentration was lower in migrating cells and higher in confluent cells than in nonconfluent cells. Thapsigargin (TG)-induced Ca2+ leak and TG-evoked Ca2+ entry were accelerated in migrating cells, whereas the latter was suppressed in confluent cells. The ATP-induced Ca2+ transient was also much larger in migrating cells than in confluent cells. These alterations were also observed in a cell as an intracellular polarization, i.e., the leading edge showed an acceleration of TG-evoked Ca2+ entry and an augmentation of the ATP-induced Ca2+ transient. Endothelial migration was significantly suppressed by TG or cyclopiazonic acid. These observations suggest that the alterations of Ca2+ store site-related Ca2+ mobilizations, i.e., Ca2+ sequestration, release, and TG-evoked Ca2+ entry, may be involved in the cellular mechanisms of endothelial migration.

Animals↗

Visceral endoderm mediates forebrain development by suppressing posteriorizing signals.

The anterior visceral endoderm (AVE) has attracted recent attention as a critical player in mouse forebrain development and has been proposed to act as "head organizer" in mammals. However, the precise role of the AVE in induction and patterning of the anterior neuroectoderm is not yet known. Here we identified a 5'-flanking region of the mouse Otx2 gene (VEcis) that governs the transgene expression in the visceral endoderm. In transgenic embryos, VEcis-active cells were found in the distal visceral endoderm at 5.5 days postcoitus (dpc), had begun to move anteriorly at 5.75 dpc, and then became restricted to the AVE prior to gastrulation. The VEcis-active visceral endoderm cells exhibited ectodermal morphology distinct from that of the other endoderm cells and consisted of two cell layers at 5.75 dpc. In the Otx2(-/-) background, the VEcis-active endoderm cells remained distal even at 6.5 dpc when a primitive streak was formed; anterior definitive endoderm was not formed nor were any markers of anterior neuroectoderm ever induced. The Otx2 cDNA transgene under the control of the VEcis restored these Otx2(-/-) defects, demonstrating that Otx2 is essential to the anterior movement of distal visceral endoderm cells. In germ-layer explant assays between ectoderm and visceral endoderm, the AVE did not induce anterior neuroectoderm markers, but instead suppressed posterior markers in the ectoderm; Otx2(-/-) visceral endoderm lacked this activity. Thus Otx2 is also essential for the AVE to repress the posterior character. These results suggest that distal visceral endoderm cells move to the future anterior side to generate a prospective forebrain territory indirectly, by preventing posteriorizing signals.

Animals↗

Hypotonic stress-induced NO production in endothelium depends on endogenous ATP.

The mechanism by which mechanical stress induces nitric oxide (NO) synthesis in endothelium is still controversial. Hypotonic stress (HTS, -20%) induced ATP release, which evoked Ca(2+) transients in bovine aortic endothelial cells (BAEC). HTS also induced NO synthesis, assessed by DAF-2 fluorescence, which was suppressed by inhibiting endogenous ATP-induced Ca(2+) transients with suramin or neomycin. Exogenously applied ATP mimicked these responses. Pretreatment with wortmannin did not affect DAF-2 fluorescence, suggesting that Akt phosphorylation was not involved in HTS-induced NO synthesis. These results indicate that endogenous ATP plays a central role in HTS-induced NO synthesis in BAEC.

Adenosine Triphosphate↗

Cloning and function of rabbit peroxisome proliferator-activated receptor delta/beta in mature osteoclasts.

Osteoclasts modulate bone resorption under physiological and pathological conditions. Previously, we showed that both estrogens and retinoids regulated osteoclastic bone resorption and postulated that such regulation was directly mediated through their cognate receptors expressed in mature osteoclasts. In this study, we searched for expression of other members of the nuclear hormone receptor superfamily in osteoclasts. Using the low stringency homologous hybridization method, we isolated the peroxisome proliferator-activated receptor delta/beta (PPARdelta/beta) cDNA from mature rabbit osteoclasts. Northern blot analysis showed that PPARdelta/beta mRNA was highly expressed in highly enriched rabbit osteoclasts. Carbaprostacyclin, a prostacyclin analogue known to be a ligand for PPARdelta/beta, significantly induced both bone-resorbing activities of isolated mature rabbit osteoclasts and mRNA expression of the cathepsin K, carbonic anhydrase type II, and tartrate-resistant acid phosphatase genes in these cells. Moreover, the carbaprostacyclin-induced bone resorption was completely blocked by an antisense phosphothiorate oligodeoxynucleotide of PPARdelta/beta but not by the sense phosphothiorate oligodeoxynucleotide of the same DNA sequence. Our results suggest that PPARdelta/beta may be involved in direct modulation of osteoclastic bone resorption.

Acid Phosphatase↗

Hypotonic stress-induced dual Ca(2+) responses in bovine aortic endothelial cells.

We have investigated the effects of hypotonic stress on intracellular calcium concentration ([Ca(2+)](i)) in bovine aortic endothelial cells. Reducing extracellular osmolarity by 5% to 40% elicited a steep Ca(2+) transient both in normal Krebs and Ca(2+)-free solutions. The hypotonic stress-induced Ca(2+) transient was inhibited by phospholipase C inhibitors (neomycin and U-73122), a P(2)-receptor antagonist (suramin), and an ATP-hydrolyzing enzyme (apyrase), suggesting that the hypotonic stress-induced Ca(2+) transient is mediated by ATP. A luciferin-luciferase assay confirmed that 40% hypotonic stress released 91.0 amol/cell of ATP in 10 min. When the hypotonic stress-induced fast Ca(2+) transient was inhibited by neomycin, suramin, or apyrase, a gradual [Ca(2+)](i) increase was observed instead. This hypotonic stress-induced gradual [Ca(2+)](i) increase was inhibited by a phospholipase A(2) inhibitor, 4-bromophenacyl bromide. Furthermore, exogenously applied arachidonic acid induced a gradual [Ca(2+)](i) increase with an ED(50) of 13.3 microM. These observations indicate that hypotonic stress induces a dual Ca(2+) response in bovine aortic endothelial cells, i.e., an ATP-mediated fast Ca(2+) transient and an arachidonic acid-mediated gradual Ca(2+) increase, the former being the predominant response in normal conditions.

Adenosine Triphosphate↗

Hypoxia-induced alterations in Ca(2+) mobilization in brain microvascular endothelial cells.

To investigate the possible cellular mechanisms of the ischemia-induced impairments of cerebral microcirculation, we investigated the effects of hypoxia/reoxygenation on the intracellular Ca(2+) concentration ([Ca(2+)](i)) in bovine brain microvascular endothelial cells (BBEC). In the cells kept in normal air, ATP elicited Ca(2+) oscillations in a concentration-dependent manner. When the cells were exposed to hypoxia for 6 h and subsequent reoxygenation for 45 min, the basal level of [Ca(2+)](i) was increased from 32.4 to 63.3 nM, and ATP did not induce Ca(2+) oscillations. Hypoxia/reoxygenation also inhibited capacitative Ca(2+) entry (CCE), which was evoked by thapsigargin (Delta[Ca(2+)](i-CCE): control, 62.3 +/- 3.1 nM; hypoxia/reoxygenation, 17.0 +/- 1.8 nM). The impairments of Ca(2+) oscillations and CCE, but not basal [Ca(2+)](i), were restored by superoxide dismutase and the inhibitors of mitochondrial electron transport, rotenone and thenoyltrifluoroacetone (TTFA). By using a superoxide anion (O(2)(-))-sensitive luciferin derivative MCLA, we confirmed that the production of O(2)(-) was induced by hypoxia/reoxygenation and was prevented by rotenone and TTFA. These results indicate that hypoxia/reoxygenation generates O(2)(-) at mitochondria and impairs some Ca(2+) mobilizing properties in BBEC.

Adenosine Triphosphate↗

Pharmacological properties of TRK-820 on cloned mu-, delta- and kappa-opioid receptors and nociceptin receptor.

We analyzed the pharmacological properties of 17-cyclopropylmethyl-3,14beta-dihydroxy-4,5alpha-epoxy-6b eta-[N-methyl-trans-3-(3-furyl)acrylamido]morphinan hydrochloride (TRK-820) using Chinese hamster ovary (CHO) cells expressing cloned rat mu-, delta- and kappa-opioid receptors and human nociceptin receptor. TRK-820 showed high affinity for the kappa-opioid receptor, with a Ki value of 3.5 +/- 0.9 nM. In CHO cells expressing kappa-opioid receptors, TRK-820 inhibited forskolin-stimulated cAMP accumulation, and the maximal inhibitory effect was equivalent to that of (+)-(5alpha,7alpha,8beta)-N-methyl-N-[7-(1-pyrrolidiny l)-1-oxaspiro-(4,5)dec-8-yl]benzeneacetamide (U69,593), a full agonist of kappa-opioid receptor. In CHO cells expressing mu-opioid receptors, TRK-820 inhibited cAMP accumulation, but the maximal inhibitory effect was significantly smaller than that of [D-Ala2, N-MePhe4, Gly-ol5]enkephalin (DAMGO), a full agonist of mu-opioid receptor. In CHO cells expressing delta-opioid receptor, the inhibitory effect of TRK-820 on cAMP accumulation was very weak. Using site-directed mutagenesis, the high affinity of TRK-820 for the kappa-opioid receptor was revealed to require Glu297. TRK-820 bound to the nociceptin receptor with a Ki value of 380 +/- 50 nM. TRK-820 by itself had no effect on cAMP accumulation in CHO cells expressing nociceptin receptors, but significantly antagonized the nociceptin (10 nM)-mediated inhibition of cAMP accumulation at high concentrations. These results indicate that TRK-820 acts as a full agonist for the kappa-opioid receptor, a partial agonist for the mu-opioid receptor and a low-affinity antagonist for the nociceptin receptor.

Animals↗

[Long-term outcome of topical cyclosporine treatment following penetrating keratoplasty].

PURPOSE: To evaluate the long-term outcome of 2% topical cyclosporine A (CsA) treatment as an adjunct to topical corticosteroid in 86 eyes after penetrating keratoplasty (PK). MATERIAL AND METHODS: The subjects were 86 eyes of 83 patients who had undergone PK and received topical CsA treatments. Ninety-seven eyes of 95 patients who had undergone PK and received similar postoperative treatments except for topical CsA treatments served as control: The clinical outcome of PK was evaluated by rates of graft survival and rejection-free graft survival using Kaplan-Meier's method and compared with the log-rank test. The patients were subdivided into high-risk and low-risk groups. The high-risk patients were those who had corneal vascularization in 2 or more quadrants of the cornea preoperatively or who received regrafting. All other patients were assigned to the low-risk group. Thirty-six eyes of the CsA group and 50 eyes of the control group were high-risk cases. RESULTS: In the high-risk patients, the rejection-free graft survival rate was 69.7% in the CsA group and 45.4% in the control group (p = 0.030). However, there was no significant difference in the graft survival rate between the two groups. In the low-risk patients, there was no significant difference in the rates of rejection-free graft survival and graft survival between the CsA and the control group. CONCLUSION: 2% topical cyclosporine is effective in reducing the risk of allograft rejection in high-risk recipients.

Administration, Topical↗

Acute glucose overload abolishes Ca2+ oscillation in cultured endothelial cells from bovine aorta: a possible role of superoxide anion.

Effects of acute glucose overload on [Ca2+]i were investigated in cultured endothelial cells from bovine aorta. Application of 0.1 micromol/L ATP elicited an oscillatory increase in [Ca2+]i (Ca2+ oscillation) in Krebs solution containing 11.5 mmol/L glucose. The frequency of Ca2+ oscillation induced by ATP increased in a concentration-dependent manner, ranging between 0.03 and 1 micromol/L. When cells were preincubated with 23 mmol/L glucose-containing Krebs solution (high glucose solution) for 3 hours, 0.1 micromol/L ATP failed to induce Ca2+ oscillation but evoked only a phasic followed by sustained increase in [Ca2+]i. Application of a higher concentration of ATP (10 micromol/L) evoked a transient increase in [Ca2+]i both in control and high glucose-treated cells. However, the falling phase of [Ca2+]i was prolonged in high glucose-treated cells. Thapsigargin (1 micromol/L), an inhibitor of endoplasmic Ca2+-ATPase, induced a transient followed by a sustained increase in [Ca2+]i in control cells. Preincubation with high glucose solution increased the rate of rise of the thapsigargin-induced increase in [Ca2+]i and abolished the sustained increase, suggesting that glucose overload accelerates Ca2+ leak from intracellular store sites and impairs Ca2+ release-activated Ca2+ entry. We found that all of the glucose overload-induced changes in Ca2+ mobilization could be mimicked by xanthine with xanthine oxidase and abolished by superoxide dismutase. These results indicate that acute glucose overload accumulates superoxide anion in bovine aortic endothelial cells, thereby diminishing ATP-induced Ca2+ oscillation through the impairment of Ca2+ homeostasis.

Adenosine Triphosphate↗