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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 307 records · Page 17Linked to original sources
PubMed1997

Transaortic approach in double-outlet right ventricle with subaortic ventricular septal defect.

The standard approach (right ventriculotomy and atriotomy) for surgical repair of double-outlet right ventricle with subaortic ventricular septal defect and pulmonary stenosis may not give an adequate view of the intracardiac defect due-to the presence of anomalous coronary artery anatomy or unusual cavity spacial relationship. Thus, a transverse aortotomy was performed and the left ventricular outflow tract was well visualized through the aortic valve and could be reconstructed precisely. Therefore, the transaortic approach also should be considered for systemic route reconstruction in this group.

Aorta↗
PubMed1997

Decrease in oral bioavailability of cyclosporin A by coadministration of probucol in rats.

To assess the pharmacokinetic interaction of cyclosporin A with probucol, we administered cyclosporin A (10 mg/kg body weight) to rats orally or intravenously with or without pretreatment of probucol (10 mg/animal, daily for 8 days). The whole blood cyclosporin A concentration-time curves after oral administration showed a 34% reduction in peak concentration and a 30% decrease in area under the blood concentration-time curve (AUC) by administration of probucol. No apparent change in elimination half-life or volume of the central compartment was observed with the treatment of probucol. After intravenous administration of cyclosporin A, the blood levels could be described by a two-compartment open model. No differences were observed in the AUC, elimination half-life or total clearance of cyclosporin A by the pretreatment of probucol. Calculated bioavailability following oral administration of cyclosporin A decreased by 33% with the treatment of probucol. These results suggest that probucol may not profoundly influence the disposition of cyclosporin A. Coadministration of probucol could decrease the fraction of absorbed cyclosporin A after oral administration.

Administration, Oral↗
PubMed1997

Methylprednisolone inhibits neutrophil-endothelial cell interactions induced by interleukin-1beta under flow conditions.

The effects of methylprednisolone (m-PSL) on IL-1beta-induced neutrophil-endothelial cell interactions, which are normally mediated by increased expression of both intercellular adhesion molecule-1 (ICAM-1) and E-selectin on endothelial cells, were examined using an in vitro flow system. Human neutrophilic polymorphonuclear leukocytes (PMN) were perfused at a shear stress of 1 dyne/cm2 on human umbilical vein endothelial cells (HUVEC) pretreated with IL-1beta (20 U/mL) for 4 hours. Many PMN adhered to IL-1-stimulated HUVEC and then migrated beneath endothelial cell monolayers. Treatment of HUVEC with m-PSL inhibited adherence and migration of PMN in a dose dependent manner. M-PSL also inhibited IL-1beta-induced upregulation of E-selectin and ICAM-1 on HUVEC in a dose dependent manner. These results suggest that m-PSL works as an anti-inflammatory agent through inhibiting PMN-endothelial cell interactions.

Adult↗
PubMed1997

Daily variation in an intensity of kaolin-induced writhing reaction in mice.

The daily variation in an intensity of kaolin-induced writhing reaction was examined in mice kept under conditions of light; 07:00 - 19:00 and dark; 19:00 - 07:00. The number of writhes was counted for 30 minutes after a single intraperitoneal injection of kaolin at 00:00, 02:00, 04:00, 06:00, 08:00, 10:00, 12:00, 14:00, 16:00, 18:00, 20:00 and 22:00. The number of writhes showed a daily variation with a peak at 18:00 and a trough at 06:00. The intensity of writhing reaction was significantly reduced by pretreatment with the bradykinin B1 (Des-Arg9-[Leu8]-BK) and B2 (icatibant) receptor antagonists. Significant daily variation in this parameter was still observed in the group with the B1 antagonist, but disappeared in the B2 antagonist-treated group. These results suggest that the kaolin-induced writhing reaction shows the daily variation with a peak at the end of the resting period and a trough at the end of the active period. The B2 receptor mediated stimuli appears to be involved in this phenomenon.

Analgesia↗
PubMed1997

Evidence that eosinophil infiltration in the OK-432/fibrinogen-injected Meth-A tumor in mice is mediated by locally produced IL-5.

It was previously demonstrated that a single injection of OK-432 (a penicillin-treated freeze-dried Streptococcus) mixed with fibrinogen into cancer tissues induces marked infiltration by eosinophils of the tumor stroma and leads to tumor necrosis. In the present study, we examined mechanisms regulating the local accumulation of eosinophils and the role of infiltrating eosinophils in tumor regression using the OK-432/fibrinogen injected Meth-A fibrosarcoma tumor. After injection of OK-432/fibrinogen into the tumor on the left flank of the BALB/c mice, eosinophil infiltration became obvious in the tumor stroma on day 3 following the accumulation of macrophages and neutrophils, was massive on day 5 and decreased by day 10. After the decrease in the infiltration of eosinophils, the tumor injected with OK-432/fibrinogen diminished markedly in size with ulceration as compared with control. Northern blot analysis revealed that expression of IL-5 mRNA in the tumor tissue was not detected on day 0, was significantly on day 3, reached the maximum on day 5, and thereafter decreased by day 10. Although intraperitoneal injection of rat anti-IL-5 monoclonal antibody in tumor bearing mice prior to OK-432 injection inhibited the infiltration of eosinophils, the antitumor effects of OK-432 persisted. In the blood, neither eosinophilia nor IL-5 activity was recognized during the course of the experiment. These results suggest that intratumoral injection of OK-432/fibrinogen induces local production of IL-5, which in turn recruits eosinophils into the tumor tissue, however, the infiltrating eosinophils do not play an important role in tumor regression.

Animals↗
PubMed1997

Effect of a glutamine-enriched diet on small bowel allograft during immunosuppressive therapy.

The effect of an orally administered glutamine-enriched elemental diet was examined following orthotopic small bowel allotransplantation using Brown Norway rats as donors and Lewis rats as recipients. The recipients was treated with FK 506 and randomized to receive glutamine-free elemental enteral diet solution (glutamine-free group), glutamine-enriched elemental diet solution containing 7500 mg of glutamine per 100 g diet (glutamine-enriched group) or standard chow (chow group) ad libitum for 7 d. There were no histological changes due to resection. Weight loss in the glutamine-enriched group was significantly less than that of the chow group. Both plasma glutamine levels and the ratio of glutamine to total amino acids in the homogenate of the graft mucosa of the glutamine-enriched group were significantly higher than those of the glutamine-fee group. Villous height and crypt depth were significantly decreased in the glutamine-free group. The BrdU labeling index in the graft epithelium and alkaline phosphatase activity in the homogenate of the graft mucosa of the glutamine-enriched group were significantly higher than those of the glutamine-free group. Therefore, orally administered glutamine-enriched elemental diet appears to promote the regeneration and differentiation of the graft mucosa following small bowel allotransplantation.

Aging↗
PubMed1997

Intercellular adhesion molecule-1 and CD18 are involved in neutrophil adhesion and its cytotoxicity to cultured sinusoidal endothelial cells in rats.

The expression of several adhesion molecules is increased on the hepatic sinusoidal endothelial cells (SECs) in various liver diseases. The objective of this study is to assess the roles of intercellular adhesion molecule 1 (ICAM-1) and of CD18 in the interaction between the neutrophils (polymorphonuclear leukocytes [PMNs]) and SECs and in the injury to SECs mediated by PMNs. Rat PMNs was perfused on SECs stimulated with tumor necrosis factor alpha (TNF-alpha) using an in vitro flow system. The number of adhered PMNs to SECs and that of PMNs migrated under SECs was counted and the effects of anti-ICAM-1, anti-CD18, and dexamethasone were studied. We also define the effect of these antibodies on the SEC injury mediated by PMNs stimulated with phorbol 12-myristate 13-acetate (PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP). TNF-alpha significantly increased the adhesion of PMNs to SECs (322 +/- 26 cells/mm2) compared with controls (194 +/- 22 cells/mm2). Anti-ICAM-1 and anti-CD18 significantly inhibited the adhesion of PMNs (131 +/- 10 and 51 +/- 30 cells/mm2, respectively). These antibodies also decreased the migration rate of PMNs (6.0% and 7.9%, respectively) compared with controls (migration rate, 21.2%). The SEC injury induced by PMA- and fMLP-activated PMNs was prevented by anti-ICAM-1 and anti-CD18. The adhesion of PMNs induced by TNF-alpha was inhibited by the treatment with dexamethasone (160 +/- 20 cells/mm2) via a down-regulation of ICAM-1 expression on SECs. The interactions between ICAM-1 and CD18 appeared to be important in the adhesion and the migration of PMNs to SECs. The injury to SECs was induced by the close interaction between the activated PMNs and SECs mediated via ICAM-1 and CD18.

Animals↗
PubMed1997

Allyl sulfides from garlic suppress the in vitro proliferation of human A549 lung tumor cells.

The present studies compared the antiproliferative effects of diallyl trisulfide (DATS) and diallyl disulfide (DADS) on cultured human neoplastic (A549) and nonneoplastic (MRC-5) lung cells. Addition of 10 microM DATS reduced A549 growth by 47%, whereas 10 microM DADS decreased growth by only 20%. DATS treatment (10 microM) did not alter MRC-5 cell growth. DATS (10 microM) caused a marked and progressive increase in intracellular Ca2+ in A549 cells during the first four hours after treatment. Intracellular Ca2+ in A549 cells exposed to DATS returned to near control levels within one hour after refeeding complete medium without DATS. Exposure to 1 microM DATS for 24 hours significantly induced apoptosis, as indicated by increased DNA fragmentation. The ability of DATS and DADS to suppress neoplastic growth is consistent with increasing evidence that several garlic components have anticarcinogenic and antitumorigenic properties.

Allyl Compounds↗
PubMed1997

Functional oxytocin receptors in bovine granulosa cells.

The aim of this study was to identify the presence of functional oxytocin (OT) receptors on bovine granulosa cells. Freshly prepared bovine granulosa cells from small (3-5 mm in diameter) or preovulatory (mature) follicles were examined for OT receptors by a radioreceptor assay. Scatchard analysis revealed that both binding capacity and affinity in granulosa cells from small follicles were significantly higher than those in granulosa cells from mature follicles (p < 0.01). With use of a reverse transcriptase polymerase chain reaction analysis, expression of OT receptor mRNA was detected in granulosa cells obtained from both small and mature follicles. When the granulosa cells obtained from small follicles were cultured in Dulbecco's Modified Eagle's Medium and Ham's F-12 medium (1:1 [v:v]) with 10% calf serum up to 72 h, as the period of culture was prolonged, the concentration of OT receptor decreased with increases of progesterone and OT release in the medium. However, the binding affinity was not changed during culture for 72 h. When bovine follicular oocytes with cumulus oophorus were cultured for 24 h in tissue culture Medium-199 with 10% fetal calf serum and OT (0-10 nM), the percentages of oocytes reaching maximum cumulus expansion were significantly increased at 0.5, 1, and 10 nM OT, although nuclear maturation in oocytes surrounded by compact cumulus cells was not affected by the addition of OT. Coexposure with OT antagonist blocked the stimulatory effect of OT on cumulus expansion, confirming the specificity of the effect. Furthermore, anti-OT rabbit serum inhibited the percentages of oocytes with expanded cumulus compared to those supplemented with normal rabbit serum (p <0.05). The overall results indicate the presence of functional OT receptors in bovine granulosa cells and support the hypothesis that OT plays a role (or roles) in regulating the function of granulosa cells as an autocrine factor during follicular growth.

Animals↗
PubMed1997

Diltiazem inhibits the late increase in extracellular potassium by maintaining glycolytic ATP synthesis during myocardial ischemia.

During myocardial ischemia, the extracellular potassium concentration increases in a triphasic pattern, an initial early increase, a constant phase, and a late increasing phase. The aim of this study was to determine whether diltiazem inhibits the late increasing phase by maintaining glycolytic adenosine triphosphate (ATP) synthesis in ischemic myocardium. The extracellular potassium concentration and pH were measured simultaneously with ion-sensitive electrodes during 30 min of global ischemia in isolated guinea-pig hearts. In the control hearts, the late increasing phase occurred 13 min after the onset of ischemia when the change in extracellular pH had reached a plateau. There was a sharp increase in the myocardial lactate level in the control hearts, which was maintained for approximately 8 min after the onset of ischemia. Iodoacetate (1 mM) led to a ATP depletion and rapid accumulation in extracellular potassium shortly after the onset of ischemia without a decrease in extracellular pH. The preischemic treatment with diltiazem (3 microM) reduced cardiac function both before ischemia and during the early period of ischemia. Diltiazem almost completely abolished the late increasing phase with a continuous decrease in extracellular pH throughout the ischemic period. The myocardial lactate level in the diltiazem-treated group increased sharply between 2 and 15 min after the onset of ischemia. The myocardial ATP level was preserved throughout the ischemic period. This study shows that diltiazem inhibits the late increasing phase in extracellular potassium by maintaining glycolytic ATP synthesis during ischemia.

Adenosine Triphosphate↗
PubMed1997

Renal primitive neuroectodermal tumor: a morphologic, cytogenetic, and molecular analysis with the establishment of two cultured cell lines.

We report two patients with renal primitive neuroectodermal tumor (PNET) in whom the diagnosis was established by both a cytogenetic and a molecular analysis. Histologically, both renal tumors were composed of uniform immature round cells with a positive immunoreactivity for O13 (p30/32 MIC2). The cytogenetic analysis with in situ hybridization (chromosome painting) demonstrated reciprocal translocation t(11;22)(q24;q12) specific to PNET in the cultured cells derived from each tumor. The reverse transcriptase-polymerase chain reaction (RT-PCR) in both tumors demonstrated EWS/ FLI-1 fusion transcripts, representing the molecular equivalent of t(11;22). A Southern blot analysis also confirmed EWS gene rearrangement in both renal tumors. In addition, the authors also established two new cell lines (designated as FU-RPNT-1 and FU-RPNT-2) from renal PNETs. When transplanted into athymic mice, FU-RPNT-1 and FU-RPNT-2 reproduced and maintained the morphologic and molecular characteristics of the original tumors. In conclusion, the detection of t(11;22) and EWS/FLI-1 fusion transcripts is considered to provide a novel adjunctive method for diagnosing renal PNET. These newly established cell lines thus may be used to investigate the biologic behavior related to renal PNETs.

Adult↗
PubMed1997

Interactions of neutrophils and endothelial cells under low flow conditions in vitro.

The interactions of polymorphonuclear leukocytes (PMN) and endothelial cells are modulated by adhesion molecules, inflammatory cytokines, and shear stress. We investigated the changes in PMN-endothelial cell interactions induced by interleukin (IL)-1 beta under low flow conditions. PMN were isolated from the venous blood of healthy adults, and endothelial cells were obtained from human umbilical veins. The number of PMN that adhered to the endothelial cells monolayer that was treated with IL-1 increased significantly at shear stresses from .5 to 4.0 dyn/cm2 as compared with untreated endothelial cells. Anti-intercellular adhesion molecule (ICAM)-1 monoclonal antibody (mAb), anti-E-selectin mAb, and anti-CD18 mAb each significantly inhibited the increase in PMN adherence induced by IL-1 at a low shear stress (1.0 dyn/cm2). Anti-CD18 mAb significantly reduced the number of PMN that migrated through the endothelial monolayer by blocking the adherence of PMN to the luminal surface of the endothelial cells, as well as their transendothelial migration. In contrast, anti-ICAM-1 and anti-E-selectin mAb each reduced the number of PMN that migrated by reducing the number of PMN that adhered to the luminal surface without significantly influencing the percent of the adherent PMN that had migrated. Although anti-L-selectin mAb reduced the adherence and migration of PMN, these effects were not statistically significant. These results indicated that under low flow conditions, as well as in the nonflow state, PMN-endothelial cell interactions were elicited via CD11/CD18 and ICAM-1 without the involvement of selectins.

Adult↗
PubMed1997

Photoresponses of transgenic Arabidopsis overexpressing the fern Adiantum capillus-veneris PHY1.

The phytochrome gene (PHY1) cDNA from the fern Adiantum capillus-veneris encodes an amino acid sequence that shows equal similarity (50-60%) to all five Arabidopsis phytochromes (PHYA-E). The A. capillus-veneris PHY1 cDNA was transformed into Arabidopsis ecotype Landsberg erecta to investigate its activity in angiosperms. Three of the resulting lines contained at least 8 times more spectrally active phytochrome than the wild type, indicating that A. capillus-veneris phytochrome can incorporate the chromophore of the host plants. Hypocotyl growth inhibition of these transgenic lines was investigated under red and far-red light. The results indicated dominant negative activity of A. capillus-veneris phy1 on the phytochrome A response in the host plants under continuous far-red light. However, the fern phytochrome did not interfere with the red-light repression of hypocotyl growth mediated by endogenous phytochrome B, and it failed to complement a phyB mutant phenotype. These observations suggest that the phy1 phytochrome molecule is too diverged from those of Arabidopsis to be fully functional.

Arabidopsis↗
PubMed1997

Effect of ageing on pancreatic hyperplasia after 90% proximal small bowel resection.

The present study was performed to examine the effect of ageing on pancreatic hyperplasia observed after proximal small bowel resection (PSBR). Young and old Wistar rats were randomly assigned to two groups, which underwent either an approximate 90% PSBR or a jejunal and ileal transection (TRC). One week after the operation, the pancreatic wet weight and the protein, DNA and RNA content of the pancreas were all significantly higher in young PSBR rats than in young TRC rats. However, no differences were seen in the old rat groups. Plasma enteroglucagon levels were elevated in both young and old PSBR rats, but the ratio of increase between the PSBR and TRC groups was significantly higher in young rats. Plasma cholecystokinin and gastrin levels did not increase after PSBR in either the young or old rats. These findings suggest that pancreatic hyperplasia observed after PSBR is attenuated by ageing, probably due to an insufficient increase in plasma enteroglucagon levels.

Aging↗
PubMed1997

Interactions between vitamin E homologues and ascorbate free radicals in murine skin homogenates irradiated with ultraviolet light.

The mechanism of oxidation of ascorbic acid in mouse skin homogenates by UV light was investigated by measuring ascorbate free radical formation using electron spin resonance signal formation. Addition of vitamin E (alpha-tocopherol or alpha-tocotrienol) had no effect, whereas short-chain homologues (2,5,7,8-tetramethyl-6-hydroxychroman-2-carboxylic acid [Trolox] and 2,2,5,7,8-pentamethyl-6-hydroxychromane [PMC]) accelerated ascorbate oxidation. The similar hydrophilicity of ascorbate, Trolox and PMC increased their interaction, thus rapidly depleting ascorbate. When dihydrolipoic acid was added simultaneously with the vitamin E homologues, the accelerated ascorbate oxidation was prevented. This was due to the regeneration of ascorbate and PMC from their free radicals by a recycling mechanism between ascorbate, vitamin E homologues and dihydrolipoic acid. Potentiation of antioxidant recycling may be protective against UV irradiation-induced damage. The rate of ascorbate oxidation in the presence of vitamin E homologues was enhanced by a photosensitizer (riboflavin) but was not influenced by reactive oxygen radical quenchers, superoxide dismutase or 5,5-dimethyl-1-pyrroline-N-oxide. These experimental results suggest that the UV irradiation-induced ascorbate oxidation in murine skin homogenates is caused by photoactivated reactions rather than reactive oxygen radical reactions.

Animals↗