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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 361 records · Page 20Linked to original sources
PubMed1996

The expression of truncated MK in human tumors.

Midkine (MK) is a heparin binding growth/differentiation factor different from fibroblast growth factors (FGFs), and is largely composed of two domains which are found by a folded polypeptide chain interconnected by disulfide bridges. Polymerase chain reaction revealed the presence of a short MK mRNA in 7 among 12 human tumor cells which expressed MK mRNA. All of 4 pancreatic carcinoma cell lines expressed the short species in addition to the full size mRNA. The short mRNA lacked an exon and resulted in the lack of a more N-terminally located domain. The truncated form of MK was found also in some surgically removed specimens of human tumors, but not in noncancerous tissue.

Base Sequence↗
PubMed1996

Comparison of the inhibitory action of synthetic capsaicin analogues with various NADH-ubiquinone oxidoreductases.

Capsaicin is a new naturally occurring inhibitor of proton-pumping NADH-ubiquinone oxidoreductase (NDH-1), that competitively acts against ubiquinone. A series of capsaicin analogues was synthesized to examine the structural factors required for the inhibitory action and to probe the structural property of the ubiquinone catalytic site of various NADH-ubiquinone reductases, including non-proton-pumping enzyme (NDH-2), from bovine heart mitochondria, potato tuber (Solanum tuberosum, L) mitochondria and Escherichia coli (GR 19N) plasma membranes. Some synthetic capsaicins were fairly potent inhibitors of each of the three NDH-1 compared with the potent rotenone and piericidin A. Synthetic capsaicin analogues inhibited all three NDH-1 activities in a competitive manner against an exogenous quinone. The modification both of the substitution pattern and of the number of methoxy groups on the benzene ring, which may be superimposable on the quinone ring of ubiquinone, did not drastically affect the inhibitory potency. In addition, alteration of the position of dipolar amide bond unit in the molecule and chemical modifications of this unit did not change the inhibitory potency, particularly with bovine heart and potato tuber NDH-1. These results might be explained assuming that the ubiquinone catalytic site of NDH-1 is spacious enough to accommodate a variety of structurally different capsaicin analogues in a dissimilar manner. Regarding the moiety corresponding to the alkyl side chain, a rigid diphenyl ether structure was more inhibitory than a flexible alkyl chain. Structure-activity studies and molecular orbital calculations suggested that a bent form is the active conformation of capsaicin analogues. On the other hand, poor correlations between the inhibitory potencies determined with the three NDH-1 suggested that the structural similarity of the ubiquinone catalytic sites of these enzymes is rather poor. The sensitivity to the inhibition by synthetic capsaicins remarkably differed between NDH-1 and NDH-2, supporting the notion that the sensitivity against capsaicin inhibition correlates well with the presence of an energy coupling site in the enzyme (Yagi, T. (1990) Arch. Biochem. Biophys. 281, 305-311). It is noteworthy that several synthetic capsaicins discriminated between NDH-1 and NDH-2 much better than natural capsaicin.

Animals↗
PubMed1996

Over-expression of a C-terminal region of phytochrome B.

In an attempt to identify domains directly involved in the signal transduction of phytochrome B (phyB), we over-expressed the achromophoric C-terminal half of phyB under control of the CaMV-35S promoter in transgenic Arabidopsis. In three independent transgenic lines, we detected accumulation of the introduced protein of predicted size at levels higher than that of the endogenous phyB by immunoblot analysis. Although these transgenic plants did not show any phenotype in the dark, enhancement of the phyB-dependent inhibition of hypocotyl elongation and reduction of the phytochrome A (phyA)-dependent inhibition were observed.

Arabidopsis↗
PubMed1996

Congenital absence and aberrant course of the internal carotid artery.

We retrospectively reviewed the imaging features of an aberrant course of the internal carotid artery (ICA) in one patient and its unilateral absence in four. Absence of the ICA was initially detected by MRI and MR angiography in both patients who underwent these examinations. CT revealed an abnormal or absent carotid canal in all cases. Radiological diagnosis by MRI and MR angiography could play an important role in the diagnosis.

Adult↗
PubMed1996

Creatine kinase release from regenerated muscles after eccentric contractions in rats.

The purpose of this study was to test the hypothesis that an increase in plasma creatine kinase (CK) activity after eccentric contractions (ECC) would be attenuated in regenerated muscle fibres. Adult male Wistar rats (aged 12-14 weeks) were randomly assigned to a treatment group (n = 14) or a control group (n = 10). In the treatment group, 1.2% barium chloride solution (BaCl2) was injected into the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles to induce degeneration and subsequent regeneration. The same amount of isotonic saline solution was injected into TA and EDL for the control group. Histological observation showed that approximately 50% of the fibres in the transverse sections of both muscles underwent necrosis 2 days after BaCl2 injection. The CK activity increased about tenfold at 2-4 h after BaCl2 injection. At 4 weeks after BaCl2 injection, when the regeneration process was almost complete, the TA and EDL of anaesthetized rats from both groups were subjected to ECC in which maximal dorsiflexion was caused by nerve electrical stimulation and the flexed foot was forcibly extended by a lever arm connected to a motor. This action was performed in 2 sets of 30 repetitions. Maximal isometric torque of the dorsiflexors decreased to about 15% (P < 0.01) of the pre-ECC value immediately after the exercise. Blood samples were collected before and 2, 4, 12, 24, 48 h after ECC. The CK activity increased significantly (P < 0.01) and peaked at 2-4 h after ECC, and there was no significant difference in the amount of CK increase between the treatment [1007 (SEM 120) IU.l-1] and the control [1064 (SEM 120) IU.l-1] group. Contrary to the hypothesis, CK release after ECC was not attenuated in muscle regenerated from BaCl2-induced myonecrosis.

Animals↗
PubMed1996

Reye's syndrome with cortical laminar necrosis: MRI.

Serial MRI findings are described in two patients with Reye's syndrome, demonstrating diffuse cortical and white matter changes. In the acute stage, T2-weighted images showed subtle but definite laminar high signal and contrast-enhanced T1-weighted images laminar enhancement, along the entire cerebral cortex bilaterally. In the chronic stage, unenhanced T1-weighted images showed diffuse cortical laminar high signal. These characteristic MRI features seemed very similar to those of laminar cortical necrosis in hypoxic brain damage. MRI also displayed delayed white matter changes with cerebral atrophy.

Atrophy↗
PubMed1996

Rebamipide protects against activation of neutrophils by Helicobacter pylori.

Our objectives were to determine whether rebamipide, a unique antiulcer agent, would inhibit adhesive reactions between neutrophils and endothelial cells as well as the production of active oxygen species from neutrophils elicited by an extract of H. pylori. A water extract of H. pylori that was prepared from biopsy materials obtained from a patient with gastric ulcer increased the surface expression of CD18 on human neutrophils isolated from peripheral blood, the adhesion of neutrophil-endothelial cells, and the production of active oxygen species by neutrophils. Rebamipide, at concentrations of 10(-5) and 10(-6) M, reduced the adherence of neutrophils to endothelial cells as well as the CD18 expression on neutrophils induced by this bacterial extract. Rebamipide also inhibited the production of active oxygen species from neutrophils stimulated by H. pylori extract. These results suggest that rebamipide protects against the gastric mucosal inflammation associated with H. pylori by inhibiting neutrophil function.

Alanine↗
PubMed1996

Altered polyamine biosynthesis with aging after massive proximal small bowel resection in rat.

We examined the effect of aging on polyamine biosynthesis in the small intestine. Two groups of male Wistar rats (young; 10-week-old, n = 40; old; 24-month-old, n = 40) underwent either a jejunal transection and reanastomosis or 90% proximal small bowel resection. The rats were sacrificed on the 1st, 2nd, 4th, and 7th postoperative day (POD). The mucosa was submitted for histological examination, weighed, and assayed for protein, DNA, RNA, and polyamine content. Ornithine decarboxylase (ODC) activity was measured and ODC mRNA in the mucosa was determined by Northern blot analysis. Compared with the values for wet weight and protein content in old rats, young rats showed significantly higher values for wet weight on the 1st and 2nd POD, and for protein content on the 1st POD, but there were no differences between young and old rats after the 4th POD. The values for ODC activity and ODC mRNA were significantly lower in old rats than in young rats on the 1st POD, but there were no differences between young and old rats after the 2nd POD. The value for putrescine in old rats was significantly lower on the 2nd POD, but was significantly higher on the 4th POD than that in young rats. The present study showed that, in old rats, the residual intestine after small bowel resection preserved sufficient adaptive capacity, but that the adaptive response was decreased. The findings in this study also suggest that a decrease in ODC mRNA expression is involved in the decreased adaptive response that occurs with aging.

Adaptation, Physiological↗
PubMed1996

Effect of ranitidine on renal clearance of lomefloxacin.

OBJECTIVE: To examine the effect of ranitidine on the renal clearance of lomefloxacin. SETTING: Department of Clinical Pharmacology, Jichi Medical School. METHODS: Lomefloxacin 200 mg and ranitidine 300 mg or its placebo were given orally in a randomised, double-blind, crossover design. Blood and urine samples were obtained during a 24-h period after dosing. RESULTS: The area under the plasma concentration-time curve and the elimination half-life of lomefloxacin were significantly increased following coadministration with ranitidine. These effects were caused by significant decreases in total (7.8%) and renal (22%) clearance of lomefloxacin. In contrast, creatinine clearance and urinary excretion of electrolytes were not influenced by ranitidine. CONCLUSION: As lomefloxacin and ranitidine are excreted in urine by renal tubular secretion, the present results suggest that the renal tubular secretion of lomefloxacin is diminished by ranitidine. As the reduction in lomefloxacin clearance is only marginal, it is probable that the drug interaction observed in this study is not of clinical significance.

Adult↗
PubMed1996

Septo-optic dysplasia with cerebellar hypoplasia in Cornelia de Lange syndrome.

Little is known about the neuropathology of Cornelia de Lange syndrome. We report a unique type of cerebral malformation combined with Cornelia de Lange syndrome in a 5-year-old female child. At autopsy, the optic systems, hypothalamic nuclei, corpus callosum and cerebellar vermis were hypoplastic, and the septum pellucidum, fornix and anterior commissure were rudimentary. The brain had malformative features of septo-optic dysplasia combined with commissural dysplasia and cerebellar vermian hypoplasia. This case suggests an interrelationship between Cornelia de Lange syndrome and midline development of the brain.

Brain↗
PubMed1996

Dermoid cyst within an upper thoracic meningocele.

A case of dermoid cyst within an upper thoracic meningocele is reported. The incidental feature of this combination is extremely rare. As upper thoracic meningocele is often associated with other spinal and intracranial abnormalities, close observation and radiologic evaluation of the craniospinal axis are necessary to obtain an exact diagnosis and to achieve an appropriate treatment.

Comorbidity↗
PubMed1996

Mechanism of the potentiating effect of NH4Cl on vasoconstriction in rat aorta.

1. In medium containing 10 or 20 mM KCl, NH4Cl (10 mM) addition significantly diminished tetraphenylphosphonium bromide (TPP+) uptake in A7r5 vascular smooth muscle cells. 2. Addition of 10 mM NH4Cl significantly potentiated the 45Ca2+ uptake of A7r5 cells in medium containing 20 mM KCl; this increased uptake could be reduced to the basal level by pretreatment with 0.1 microM verapamil. 3. In rat aortic strips, KCl at 10 mM induced a slight contraction, that was greatly potentiated by the simultaneous addition of 10 mM NH4Cl. In this case, also, pretreatment with verapamil (1 microM) completely abolished the NH4Cl-potentiating effect. 4. The results suggest that ammonium ion amplifies the K(+)-induced contraction of rat aorta by facilitating transmembraneous Ca2+ influx through the voltage-dependent calcium channel, which may be due to potentiation of KCl-induced depolarization of the plasma membrane.

Ammonium Chloride↗
PubMed1996

In vivo evaluation of a fluorine-acryl-stylene-urethane-silicone antithrombogenic coating material copolymer for intravascular stents.

RATIONALE AND OBJECTIVES: We evaluated the effectiveness of a fluorine-acryl-styrene-urethane-silicone (FASUS) copolymer as an antithrombogenic coating material for intravascular stents in dogs. METHODS: FASUS copolymer-coated stents were placed in the right iliac veins, and uncoated 304 stainless steel stents were placed in the left iliac veins. We examined platelet deposition, microthrombus formation, and neointimal hyperplasia 4 weeks after stent placement by measuring the activity of 111In-labeled platelets, by using scanning electron microscopy, and by measuring neointimal thickness. RESULTS: Platelet deposition was significantly decreased on coated than on uncoated stents (p < .05). A less pronounced increase in red blood cell deposition was observed at the sites of the coated than uncoated stents (p < .05). Neointimal thickness 4 weeks after stent placement also was significantly less at the sites of the coated stents (0.27 +/- 0.08 mm versus 0.48 +/- 0.23 mm, p < .05). CONCLUSION: FASUS copolymer coating over the vascular stent is effective for preventing thrombus formation and neointimal hyperplasia.

Animals↗
PubMed1996

Nuclear localization activity of phytochrome B.

Phytochromes are soluble red/far-red-light photoreceptor proteins which mediate various photomorphogenic responses of plants. Despite much effort, the signal transduction mechanism of phytochrome has remained obscure. Phytochromes are encoded by a small multigene family in Arabidopsis. Among the members of the family, phytochrome A (phyA) and B (phyB) are the best characterized. PhyB contains putative nuclear localization signals within its C-terminal region. Transgenic Arabidopsis plants were produced with expressed a fusion protein consisting of GUS and C-terminal fragments of phyB. GUS staining from the fusion protein in these transgenic plants was observed in the nucleus, which suggests that the nuclear localization signal of the fragment is functional. Next, it was examined whether the endogenous phyB was detected in the nucleus. Nuclei were isolated from the light-grown wild-type Arabidopsis leaves and subjected to the immunoblot analysis. The result indicated that a substantial fraction of total phyB was recovered in the isolated nuclei. This result was further confirmed by the immunocytochemical analysis of the protoplasts. Finally, the effects of light treatments on the levels of phyB in the isolated nuclei were examined. Dark adaptation of the plants before the nuclear isolation reduced the levels of phyB. The reduction was accelerated by irradiation of plants with far-red light before the transfer to darkness. Thus, nuclear localization of phyB was suggested to be light-dependent.

Arabidopsis↗
PubMed1996

Dietary rosemary suppresses 7,12-dimethylbenz(a)anthracene binding to rat mammary cell DNA.

Commercially available ground rosemary powder was examined for its ability to modify the in vivo binding of 7,12-dimethylbenz(a)anthracene (DMBA) metabolites to mammary cell DNA in 55-d-old rats fed diets containing varying quantities and types of lipids. Supplementing a casein-based diet containing 20% corn oil with 1 % rosemary for 2 wk reduced by 76% the occurrence of DMBA-induced DNA adducts occurring 24 h after treatment with 50 mg DMBA/kg body weight. A comparable reduction in DNA adducts (66%) occurred when 0.5% rosemary was added to a diet containing 20% corn oil, and the quantity of DMBA given was reduced to 25 mg/kg body weight. The reduction in the occurrence of adducts occurring 24 h after DMBA treatment caused by 0.5% dietary rosemary was greater (P < 0.05) when added to a diet containing 20% corn oil than when added to a diet containing 5% corn oil and 15% coconut oil. Rosemary, 1% but not 0.5%, reduced DMBA-induced DNA adducts when the diet contained 5% corn oil. These studies demonstrate that rosemary is effective in reducing the binding of DMBA metabolites to rat mammary cell DNA. Furthermore, the present studies demonstrate that the benefits of rosemary are dependent on the source and concentration of dietary lipids.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Renal primitive neuroectodermal tumor: an immunohistochemical and cytogenetic analysis.

The cytogenetic and morphologic characteristics of a case with a primitive neuroectodermal tumor (PNET) arising from the left kidney in a 22 year old man are presented. The patient was detected as having a left renal mass with a tumor embolus in the inferior vena cava and multiple pulmonary metastases. A radical nephrectomy with tumor embolectomy of the inferior vena cava, along with a resection of the pulmonary nodules were performed. Histologic examination revealed a dense proliferation of small round cells with many Homer-Wright type rosettes and perivascular pseudorosettes. Immunohistochemically, the tumor cells stained strongly positive for HBA71(p30/32MIC2), a surface glycoprotein specific to PNET and Ewing's sarcoma. In addition, the tumor cells expressed several neural markers (neuron specific enolase, neurofilament, synaptophysin, and Leu-7) and vimentin, while the epithelial, muscular, and lymphocytic markers were negative in the tumor cells. Cytogenetic analysis of cultured tumor cells showed a reciprocal translocation t(11;22)(q24;q12) that is considered to be specific to PNET and Ewing's sarcoma. In conclusion, this case suggested that a karyotyping analysis is a useful diagnostic tool for renal PNET, and it may therefore be utilized to help distinguish between difficult cases of small round cell tumors and Wilms' tumor of the kidney.

Adult↗