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H Sakai

Publications and source records attributed to H Sakai.

At least 163 records · Page 9Linked to original sources
PubMed2001

Prostaglandin E2 regulates the expression of basic fibroblast growth factor messenger RNA in normal human fibroblasts.

Prostaglandin E2 (PGE2) has been reported to control angiogenesis and play an important role in wound healing in soft tissues, although the precise mechanism is still unknown. Since basic fibroblast growth factor (bFGF) has been reported to generate neovascularization, PGE2 and bFGF might work closely, or one might control the expression of the other. In this study, we demonstrate that PGE2 enhances the expression of bFGF in normal human fibroblasts, and that calcium ionophore, A23187, and adenylate cyclase activator, forskolin, also enhances the expression bFGF mRNA. These results suggest that enhancement of bFGF mRNA stimulated by PGE2 is mainly controlled through EP1 or EP2 and EP4 receptor. In conclusion, our findings suggest that the mechanism of PGE2-induced angiogenesis and wound hearing in soft tissue could be mediated by bFGF through EP1 or EP2 and EP4 receptor.

Adenylyl Cyclases↗
PubMed2001

[Problems involved in endovascular embolization of intracranial aneurysms with three-dimensional Guglielmi detachable coils].

We experienced nine cases of intracranial aneurysms which were treated with three-dimensional Guglielmi detachable coils (3D-GDC). 3D-GDC is useful in the construction of the initial frame for the embolization of aneurysms, but it also has certain disadvantages for achieving successful treatment. Nine patients with nine intracranial aneurysms were treated with 3D-GDC for initial framing from October, 1999 to September, 2000 at the National Cardio-Vascular Center, Japan. Angiographically complete and successful occlusion was performed in only three patients. Four patients developed parent artery stenosis due to small loops of the 3D-GDC protruding from the aneurysm. Two patients experienced incomplete occlusion because small loops of the 3D-GDC caused cells to form in the framing, and additional coils could not be inserted into some cells. 3D-GDC is useful as an initial framing coil, but we should be careful when placing additional coils into an aneurysm because we cannot predict the effect of the small loops of 3D-GDC on the embolization of aneurysms.

Aged↗
PubMed2001

[Stenting for the occlusive carotid and subclavian arteries in Takayasu arteritis].

The authors report the initial results of stenting in four patients of Takayasu arteritis for 11 occlusive carotid and subclavian arteries between January 1999 and December 2000. The lesions included stenoses of two right subclavian, three right common carotid, two left common carotid, and two left subclavian arteries, and total occlusion of two subclavian arteries. A total of 14 stents were implanted in 10 arterial lesions, resulting in a 91% procedural success rate. One failure was due to inability to cross the total occlusion of the subclavian artery. Procedural complications and problems were pain during balloon angioplasty in three patients, vaso-vagal reflex in two, carotid artery perforation associated with transient horseness in one, and stent migration in one. There was no permanent morbidity. Follow-up over a mean duration of 12 months revealed one symptomatic recurrence of left subclavian stenosis, followed by a successful re-dilatation. The results of the current study indicated that primary stenting is an excellent therapeutic option for the occlusive carotid and subclavian arteries in Takayasu arteritis. A long-term follow-up is required to determine the response or behavior of stented segments of the affected arteries.

Adult↗
PubMed2001

Trace element accumulation in hawksbill turtles (Eretmochelys imbricata) and green turtles (Chelonia mydas) from Yaeyama Islands, Japan.

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Ba, Hg, Tl, and Pb) were determined in the liver, kidney, and muscle of green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Yaeyama Islands, Okinawa, Japan. Accumulation features of trace elements in the three tissues were similar between green and hawksbill turtles. No gender differences in trace element accumulation in liver and kidney were found for most of the elements. Significant growth-dependent variations were found in concentrations of some elements in tissues of green and hawksbill turtles. Significant negative correlations (p < 0.05) were found between standard carapace length (SCL) and the concentrations of Cu, Zn, and Se in the kidney and V in muscle of green turtles and Mn in the liver, Rb and Ag in kidney, and Hg in muscle of hawksbill turtles. Concentrations of Sr, Mo, Ag, Sb, and Tl in the liver, Sb in kidney, and Sb and Ba in muscle of green turtles and Se and Hg in the liver and Co, Se, and Hg in kidney of hawksbill turtles increased with an increase in SCL (p < 0.05). Green and hawksbill turtles accumulated extremely high concentrations of Cu in the liver and Cd in kidney, whereas the levels of Hg in liver were low in comparison with those of other higher-trophic-level marine animals. High accumulation of Ag in the liver of green turtles was also observed. To evaluate the trophic transfer of trace elements, concentrations of trace elements were determined in stomach contents of green and hawksbill turtles. A remarkably high trophic transfer coefficient was found for Ag and Cd in green turtles and for Cd and Hg in hawksbill turtles.

Animals↗
PubMed2000

Pharmacological profile of YM-31636, a novel 5-HT3 receptor agonist, in vitro.

We investigated the in vitro pharmacological profile of YM-31636 (2-(1H-imidazol-4-ylmethyl)-8H-indeno[1,2-d]thiazole monofumarate). In cloned human 5-HT3A receptors, YM-31636 had a pKi value of 9.67 vs. ramosetron and pKi values for other 5-HT3 receptor agonists were less than 7. YM-31636 showed very low affinities for other receptors. YM-31636 induced contraction of isolated guinea pig distal colon. The intrinsic activity was approximately 0.90 compared with 5-hydroxytryptamine's (5-HT) 1.0, and the potency was 26 times greater than that of 5-HT. YM-31636 increased short-circuit current (Isc) in the isolated guinea pig distal colon. In this case, the relative intrinsic activity was approximately 0.19. In isolated guinea pig right atrium, YM-31636 induced tachycardia with the relative intrinsic activity of approximately 0.23. All these effects of YM-31636 were antagonized by ramosetron, a selective 5-HT3 receptor antagonist. These results suggest that YM-31636 is a potent and selective 5-HT3 receptor agonist, preferentially acting on the contraction of the colon.

Acetylcholine↗
PubMed2000

The alpha and beta subunit of the nascent polypeptide-associated complex have distinct functions.

Nascent polypeptide-associated complex (NAC) is probably the first cytosolic protein to contact nascent polypeptide chains emerging from ribosomes. In this way NAC prevents inappropriate interactions with other factors. Eventually other factors involved in targeting and folding, like the Signal Recognition Particle or cytosolic chaperones, must gain access to the nascent chain. All NAC preparations to date consist of two copurifying polypeptides. Here we rigorously show that these two polypeptides, termed alpha- and betaNAC, form a very stable complex in vivo and in vitro and that a functional complex can be reconstituted from the individual subunits. A dissection of the contributions of the individual subunits to NACs function revealed that both subunits are in direct contact with nascent polypeptide chains on the ribosome and that both contribute to the prevention of inappropriate interactions. However, betaNAC alone directly binds to the ribosome and is sufficient to prevent ribosome binding to the endoplasmic reticulum membrane.

Amino Acid Sequence↗
PubMed2000

Photoreduction of methemoglobin by irradiation in the near-ultraviolet region.

Ferric metHb can be photoreduced to the ferrous state by direct photoexcitation in the near-ultraviolet region. In this research, we studied the mechanism and facilitating conditions for the photoreduction and the resulting restoration of O(2) binding. MetHb in phosphate-buffered saline or pure water in a CO atmosphere was photoreduced to form HbCO by illuminating the N band (365 nm), one of the porphyrin pi --> pi transitions, whereas the photoreduction did not occur in Ar, N(2), or O(2). The transient absorption spectrum exhibited the generation of deoxyHb within 30 ns in both the CO and Ar atmospheres; however, only in CO did the subsequent CO binding inhibit the back reaction. The photoreduction rate was dependent on the pH and ligand anions, showing that aquametHb in the high-spin state was predominant for the photoreduction. Axial ligand-to-metal charge-transfer (LMCT) bands overlap with the Soret and Q bands in metHb; however, the excitation of these bands showed little photoreduction, indicating that the contribution of these LMCT bands is minimal. Excitation of the N band significantly contributes to the photoreduction, and this is facilitated by the external addition of mannitol, hyaluronic acid, Trp, Tyr, etc. Especially, Trp allowed the photoreduction even in an Ar atmosphere, and the reduced Hb can be converted to HbO(2) by O(2) bubbling. One mechanism of the metHb photoreduction that is proposed on the basis of these results consists of a charge transfer from the porphyrin ring to the central ferric iron to form the porphyrin pi cation radical and ferrous iron by the N band excitation, and the contribution of the amino acid residues in the globin chain as an electron donor or an electron pathway.

Anions↗
PubMed2000

Tri-n-butyltin-induced change in cellular level of glutathione in rat thymocytes: a flow cytometric study.

Since some of organotins, accumulated in edible mollusks of aquatic environments, exert a variety of toxic actions on experimental animals, it causes concern for the health of humans. We examined the effects of tri-n-butyltin chloride (TBT) and other organotins (triethyltin chloride, trimethyltin chloride, triphenyltin chloride and tetrabutyltin) on cellular content of glutathione (GSH) in rat thymocytes using a flow cytometer to further characterize the toxicity of TBT. When the cells were incubated with TBT at concentrations of 3 nM or more for 15 min, the cellular content of GSH dose-dependently decreased. However, it completely or partly recovered until 180 min even in the continued presence of TBT. This recovery was temperature-sensitive, suggesting an involvement of metabolic process. The efficacy of TBT to decrease the cellular content of GSH was greater than those of other organotins. Results suggest that TBT and some organotins at environmentally relevant (nanomolar) concentrations significantly reduce the cellular content of GSH, suggesting that they increase the vulnerability to some biological and chemical insults.

Animals↗
PubMed2000

Enhanced shear-induced von Willebrand factor binding to platelets in acute myocardial infarction.

Recent investigations have suggested that von Willebrand factor (vWF) plays a crucial role in platelet thrombosis under flow conditions. The effects of plasma obtained from 15 patients with acute myocardial infarction and 10 patients with the chest pain syndrome as controls, on shear-induced vWF binding to platelets and subsequent platelet activation, as evidenced by microparticle release, were investigated by quantitative flow cytometry. Platelet-rich plasma was obtained from a 38-year-old healthy male volunteer with blood type O. Stored plasma from either the acute myocardial infarction or control patients was then added to the freshly prepared platelet-rich plasma in equal volumes. The mixtures were then exposed to specific shear rates in an optically modified cone-plate viscometer. The number of vWF molecules bound to the platelet surface and the number of microparticles released from the platelets were then measured by quantitative flow cytometry using an FITC-conjugated anti-vWF monoclonal antibody. The shear-induced increase in vWF binding to the platelet surface was enhanced in the presence of plasma from patients with acute myocardial infarction (acute myocardial infarction plasma). The shear-induced release of microparticles from platelets was enhanced from 889+/-134 in the presence of control plasma to 1045+/-222 in the presence of the acute myocardial infarction plasma (p<0.05). Acute myocardial infarction plasma also reduced the shear rate threshold required to induce measurable shear-induced vWF binding from 10800 s(-1) to 9000 s(-1). We conclude that the plasma of acute myocardial infarction patients contains factors that enhance shear-induced vWF binding and vWF-mediated platelet activation, which may contribute to thrombotic re-occlusions of the coronary arteries in patients who have received reperfusion treatments.

Aged↗
PubMed2000

Heme structure of hemoglobin M Iwate [alpha 87(F8)His-->Tyr]: a UV and visible resonance Raman study.

Heme structures of a natural mutant hemoglobin (Hb), Hb M Iwate [alpha87(F8)His-->Tyr], and protonation of its F8-Tyr were examined with the 244-nm excited UV resonance Raman (UVRR) and the 406.7- and 441.6-nm excited visible resonance Raman (RR) spectroscopy. It was clarified from the UVRR bands at 1605 and 1166 cm(-)(1) characteristic of tyrosinate that the tyrosine (F8) of the abnormal subunit in Hb M Iwate adopts a deprotonated form. UV Raman bands of other Tyr residues indicated that the protein takes the T-quaternary structure even in the met form. Although both hemes of alpha and beta subunits in metHb A take a six-coordinate (6c) high-spin structure, the 406.7-nm excited RR spectrum of metHb M Iwate indicated that the abnormal alpha subunit adopts a 5c high-spin structure. The present results and our previous observation of the nu(Fe)(-)(O(tyrosine)) Raman band [Nagai et al. (1989) Biochemistry 28, 2418-2422] have proved that F8-tyrosinate is covalently bound to Fe(III) heme in the alpha subunit of Hb M Iwate. As a result, peripheral groups of porphyrin ring, especially the vinyl and the propionate side chains, were so strongly influenced that the RR spectrum in the low-frequency region excited at 406.7 nm is distinctly changed from the normal pattern. When Hb M Iwate was fully reduced, the characteristic UVRR bands of tyrosinate disappeared and the Raman bands of tyrosine at 1620 (Y8a), 1207 (Y7a), and 1177 cm(-)(1) (Y9a) increased in intensity. Coordination of distal His(E7) to the Fe(II) heme in the reduced alpha subunit of Hb M Iwate was proved by the observation of the nu(Fe)(-)(His) RR band in the 441.6-nm excited RR spectrum at the same frequency as that of its isolated alpha chain. The effects of the distal-His coordination on the heme appeared as a distortion of the peripheral groups of heme. A possible mechanism for the formation of a Fe(III)-tyrosinate bond in Hb M Iwate is discussed.

Amino Acid Substitution↗
PubMed2000

Serum testosterone:estradiol ratio and the development of hepatocellular carcinoma among male cirrhotic patients.

The reason for the large male predominance in the occurrence of hepatocellular carcinoma (HCC) remains unknown, and sex hormones may contribute to this phenomenon. We examined possible associations of serum levels of testosterone, free testosterone, estradiol, sex hormone binding globulin, and testosterone:estradiol ratio (T:E2 ratio) with HCC development in a follow-up study of 46 Japanese male patients with liver cirrhosis predominantly of hepatitis C virus origin (76%). Serum samples were collected between December 1985 and December 1987, and the patients were completely followed until the end of 1995 for an average of 5.1 years. During the follow-up period, 20 patients (43%) developed HCC. Univariate analysis demonstrated that serum T:E2 ratio and testosterone were significant predictors of HCC; the hazard ratios (and 95% confidence intervals) in the middle and upper tertiles relative to the lower tertile were 2.0 (0.5-7.6) and 4.0 (1.1-14.6; P trend = 0.03) for T:E2 ratio and 0.8 (0.2-3.1) and 2.9 (1.0-8.5; P trend = 0.05) for testosterone. Adjustment for age, serum albumin, hepatitis virus markers, and other clinicobiological variables substantially increased the corresponding hazard ratios. In multivariate analysis, serum free testosterone appeared to be associated with increased risk, yet independent associations with estradiol and sex hormone binding globulin were not evident. These results indicate that elevated serum testosterone, together with decreased serum estrogens, may promote the development of HCC in cirrhosis.

Adult↗
PubMed2000

The adoption of a twisted structure of importin-beta is essential for the protein-protein interaction required for nuclear transport.

Importin-beta is a nuclear transport factor which mediates the nuclear import of various nuclear proteins. The N-terminal 1-449 residue fragment of mouse importin-beta (impbeta449) possesses the ability to bidirectionally translocate through the nuclear pore complex (NPC), and to bind RanGTP. The structure of the uncomplexed form of impbeta449 has been solved at a 2.6 A resolution by X-ray crystallography. It consists of ten copies of the tandemly arrayed HEAT repeat and exhibits conformational flexibility which is involved in protein-protein interaction for nuclear transport. The overall conformation of the HEAT repeats shows that a twisted motion produces a significantly varied superhelical architecture from the previously reported structure of RanGTP-bound importin-beta. These conformational changes appear to be the sum of small conformational changes throughout the polypeptide. Such a flexibility, which resides in the stacked HEAT repeats, is essential for interaction with RanGTP or with NPCs. Furthermore, it was found that impbeta449 has a structural similarity with another nuclear migrating protein, namely beta-catenin, which is composed of another type of helix-repeated structure of ARM repeat. Interestingly, the essential regions for NPC translocation for both importin-beta and beta-catenin are spatially well overlapped with one another. This strongly indicates the importance of helix stacking of the HEAT or ARM repeats for NPC-passage.

Amino Acid Sequence↗
PubMed2000

Protein expression and functional difference of membrane-bound and soluble receptor activator of NF-kappaB ligand: modulation of the expression by osteotropic factors and cytokines.

A variety of humoral factors modulate the osteoclastogenesis. Receptor activator of NF-kappaB ligand (RANKL) expressed on osteoblast/stromal lineage cells plays a pivotal role to transduce an essential differentiation signal to osteoclast lineage cells through binding to its receptor, RANK, expressed on the latter cell population; however, the difficulty to detect RANKL protein expression hampers us in investigating the regulation of RANKL expression by humoral factors. To determine protein expression of RANKL, we have established a new method, named as a ligand-receptor precipitation (LRP) Western blot analysis, which can specifically concentrate the target protein by the use of specific binding characteristic between RANKL and RANK/osteoprotegrin (OPG). RANKL protein expression in the postnuclear supernatant was not detected by common Western blotting, but LRP Western blot analysis clearly showed that RANKL is produced as a membrane-bound protein on murine osteoblasts/stromal cells, and cleaved into a soluble form by metalloprotease. Cytokines stimulating the osteoclastogenesis, such as IL-1beta, IL-6, IL-11, IL-17, and TNF-alpha, increased the expression of RANKL with decrease of OPG expression in osteoblasts/stromal cells. In contrast, cytokines inhibiting the osteoclastogenesis, such as IL-13, INF-gamma, and TGF-beta1 suppressed the expression of RANKL and/or augmented OPG expression. Functional difference between membrane-bound and soluble RANKL was demonstrated, which showed that membrane-bound RANKL works more efficiently than soluble RANKL in the osteoclastogenesis developed from murine bone marrow cell culture. The present study indicates the usefulness of LRP Western blot analysis, which shows that the modulation of osteoclastogenesis by humoral factors is achieved, in part, by regulation of the expression of RANKL and OPG in osteoblast/stromal lineage cells.

Animals↗
PubMed2000

Bisphosphonate administration alters subcellular localization of vacuolar-type H(+)-ATPase and cathepsin K in osteoclasts during experimental movement of rat molars.

This study was designed to clarify the effects of bisphosphonate (BP) administration on structure and functions of osteoclasts in alveolar bone resorption during experimental movement of rat molars. To produce orthodontic force, elastic band was inserted between the upper first and second molars for 4 days, and dissected maxillae were then examined by means of light and electron microscopic immunocytochemistry for vacuolar-type H(+)-ATPase and lysosomal cystein proteinase, cathepsin K in osteoclasts. Vacuolar-type H(+)-ATPase and cathepsin K in osteoclasts are the most important enzymes for demineralization of apatite crystals and degradation of bone type-I collagen, respectively. At 1 day before elastic band insertion, BP was administered intraperitoneally. Control rats received the same volume of physiologic saline. In BP-administered rats, most osteoclasts exhibited either irregularly-formed ruffled borders and clear zones or only clear zones of various degrees of extension. Subcellular localization and expression of both vacuolar-type H(+)-ATPase and cathepsin K was significantly decreased in such osteoclasts with impaired ruffled borders and/or only clear zones by BP administration. In particular, cathepsin K secretion by osteoclasts towards resorption lacunae was markedly inhibited by BP administration. Our results indicate for the first time that BP administration significantly impair the osteoclast structure and reduces expression of both vacuolar-type H(+)-ATPase and cathepsin K in osteoclasts during tooth movement.

Animals↗
PubMed2000

Relationship between flow cytometric DNA ploidy and nuclear grade with endocrine dysfunction in adrenal cortical adenomas.

OBJECTIVES: To determine the relationship among the DNA ploidy, histopathologic features, and clinical syndrome in adrenal cortical adenomas, because the cells often show variability in nuclear size and configuration. METHODS: Our study included 44 adenomas associated with primary aldosteronism and 23 adenomas associated with Cushing syndrome. Normal adrenal glands from patients with renal carcinoma served as the controls. Paraffin-embedded tissues were examined for DNA content by flow cytometry. The mean percentage of G(2)/M (4C%) of the control samples was 3.8%. Tetraploid was represented by a histogram with both a 4C peak greater than 9% (mean + 2.4 SD of control samples) and a small 8C peak. RESULTS: Flow cytometric analysis revealed diploidy in 30, tetraploidy in 27, and aneuploidy in 8 of the 67 adenomas; 2 adenomas could not be classified. All 17 normal adrenal glands showed diploidy. A significant relationship was noted between DNA ploidy and the clinical syndrome (ie, a larger proportion of adenomas with primary aldosteronism had a tetraploid DNA histogram compared with adenomas with Cushing syndrome, P <0. 0001). Adenomas with primary aldosteronism had a significantly higher nuclear grade (III or IV) than did tumors with Cushing syndrome (P = 0.033). A significant relationship was also observed between DNA ploidy and nuclear grade in 57 euploid tumors, with tetraploid tumors often showing the highest nuclear grade (P = 0. 037). CONCLUSIONS: Our results have demonstrated that adrenal cortical adenomas associated with primary aldosteronism often reveal severe nuclear pleomorphism, indicating that nuclear pleomorphism might be due to a tetraploid stemline.

Adenoma↗
PubMed2000

Thromboxane A(2)-mediated Cl(-) secretion induced by platelet-activating factor in isolated rat colon.

Thromboxane A(2) is a novel endogenous secretagogue of Cl(-) secretion in the distal colon. Here, we examined if the Cl(-) secretion caused by platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is mediated by thromboxane A(2) production using isolated mucosae of the rat colon. Furosemide (100 microM) and 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB; 300 microM) completely inhibited PAF (10 microM)-induced increase in short-circuit current (Isc) across the mucosa, indicating that PAF caused a Cl(-) secretion in the rat colon. A selective thromboxane A(2) receptor antagonist (sodium(E)-11-[2-(5, 6-dimethyl-1-benzimidazolyl)-ethylidene]-6,11-dihydrobenz[b, e]oxepine-2-carboxylate monohydrate; KW-3635), and a selective thromboxane synthase inhibitor (sodium 4-[alpha-hydroxy-5-(1-imidazolyl)-2-methylbenzyl]-3, 5-dimethylbenzoate dihydrate; Y-20811) inhibited the PAF-induced Cl(-) current in a concentration-dependent manner. The IC(50) values of KW-3635 and Y-20811 were 2.1 and 0.5 microM, respectively. 30 microM KW-3635 and 1 microM Y-20811 inhibited the PAF response by 92% and 83%, respectively. These inhibitors did not affect the prostaglandin E(2)-induced increase in Isc. A 5-lipoxygenase-activating protein inhibitor (3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-t-butylthioindol-2-yl]-2, 2-dimethyl-propanoic acid sodium; MK-886) (5 microM) did not affect the PAF-induced Cl(-) current. The present study suggests that the PAF-induced Cl(-) secretion in the rat colonic mucosa is mainly mediated by a release of thromboxane A(2).

5-Lipoxygenase-Activating Proteins↗
PubMed2000

Precise measurement of dp elastic scattering at 270 MeV and three-nucleon force effects

The cross section, the deuteron vector A(d)(y) and tensor analyzing powers A(ij), the polarization transfer coefficients K(y('))(ij), and the induced polarization P(y(')) were measured for the dp elastic scattering at 270 MeV. The cross section and A(d)(y) are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, A(ij), K(y('))(ij), or P(y(')) are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models.

Journal Article↗