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Biomedical subjects

N Oku

Publications and source records attributed to N Oku.

At least 163 records · Page 9Linked to original sources
PubMed1990

Inhibitory effect of local anesthetics on Na+/H+ antiporter in brush border membrane-reconstituted vesicles.

The effects of three local anesthetics, lidocaine, dibucaine, and tetracaine, on Na+/H+ antiporter activity were examined in brush border membrane-reconstituted vesicles. Lidocaine at 10 microM inhibited H+ efflux in the presence of an inward Na+ gradient, suggesting that this anesthetic specifically inhibits the Na+/H+ antiporter. On the other hand, dibucaine and tetracaine decreased H+ efflux even in the absence of a Na+ gradient.

Anesthetics, Local↗
PubMed1990

A validation study on the reproducibility of transcranial Doppler velocimetry.

The transcranial Doppler method for the measurement of intracranial arterial blood flow velocity is a useful noninvasive technique with a number of applications. The present study validated the reproducibility of this method for repeated measurements of flow velocity in the middle cerebral and basilar arteries. Fifteen healthy volunteers were studied. Measurements were made twice by one examiner and once by another in a single day and again by the first examiner on another day. The reproducibility was evaluated by calculating the correlation coefficient (r) and the coefficient of variation (CV) of the difference between the values obtained from each pair of measurements. Although depending on the examiner, the time interval between the examinations and the vessels studied some differences were noted in the reproducibility, both the r (0.69-0.95) and CV (6.7%-19.5%) values in the whole study were good enough to warrant the applicability of this method for the repeated measurements of the intracranial arterial blood flow velocity in future studies.

Cerebral Arteries↗
PubMed1990

Giant neutrophils derived from tetraploid leukemic clone in an acute myeloblastic leukemia: cytofluorometric study.

Near-tetraploid chromosomes were observed in a patient with acute myeloblastic leukemia with maturation (M2 in FAB classification). Large and morphologically bizarre leukemic cells and giant neutrophils in each maturation stage were observed in both peripheral blood and bone marrow. Cytogenetic studies revealed that the main stem line was 93; XXYY, +9, and DNA cytofluorometry showed that these large leukemic cells and giant neutrophils had 4C DNA content. These findings strongly suggested that these giant neutrophils were derived from leukemic clone with tetraploidy.

Aged↗
PubMed1990

Glucuronate-modified liposomes with prolonged circulation time.

For the purpose of obtaining liposomes with long circulation time in blood, we synthesized 1-O-palmityl-D-glucuronic acid (PGlcUA) and incorporated it into the liposomal membranes. The clearance of the PGlcUA-liposomes composed of dipalmitoylphosphatidylcholine (DPPC), cholesterol, and PGlcUA (40:40:20 as a molar ratio) from blood and their tissue distribution were compared with those of dipalmitoylphosphatidylglycerol (DPPG)-liposomes (DPPC/cholesterol/DPPG = 40:40:20). When [3H]inulin-loaded PGlcUA-liposomes and DPPG-liposomes were intravenously injected into rats, the half-life of the PGlcUA-liposomes in the blood appeared to be 1.7-fold longer than that of DPPG-liposomes. Radioactivities present in plasma and various tissues were measured 22 h after administration of these liposomes, and radioactivity remaining in the plasma was 2.5-fold greater when PGlcUA-liposomes were injected. The distribution pattern of [3H]inulin in PGlcUA-liposomes was similar to that in DPPG-liposomes. The radioactivity recovered in urine was 25% lower in rats treated with PGlcUA-liposomes than in those treated with DPPG-liposomes. Since both PGlcUA- and DPPG-liposomes exhibited similar size distribution and zeta-potential, glucuronic acid, rather than negative charge, on the liposomal surface appears to endow liposomes with a longer circulation time in the bloodstream.

Animals↗
PubMed1990

[Diclonal gammopathy (IgG kappa, IgA lambda) with nephrotic syndrome terminating into IgA lambda myeloma after three years--report of a case].

A 43-year-old man was admitted to our hospital because of legs edema and periorbital edema in Dec. 1983. Laboratory findings showed massive proteinuria (3.7 g/day), Bence Jones protein (BJP) in urine, and hypoproteinemia. Peripheral blood examinations were normal and a bone marrow aspiration showed hypocellularity with slight increase of monocytes and plasma cells. Serum immunoelectrophoresis showed two M-components (IgG kappa, IgA lambda). Serum IgG was 1,690 mg/dl, IgA 379 mg/dl and IgM 160 mg/dl. No remarkable findings were obtained in bone survey, Ga-scintigraphy and rectal biopsy, and a diagnosis of diclonal gammopathy with nephrotic syndrome was made. In Aug. 1986, serum IgA started to increase rapidly with concomitant decrease IgG. He died of pneumonia due to pancytopenia in Dec. 1986, when serum IgG was 450 mg/dl, IgA 1,014 mg/dl, and IgM less than 39 mg/dl. Immunoelectrophoresis showed two M-components (IgG kappa, IgA lambda) in serum and BEP (kappa, lambda), IgG (kappa) and IgA (lambda) in urine. An autopsy showed massive infiltration of myeloma cells which were positive for lambda light chain in bone marrow, suggesting a development of myeloma from a diclonal gammopathy in about 3 years.

Adult↗
PubMed1990

Activation of the serum-response and TPA-response elements by expression of the v-abl protein: comparison of the mode of action of the v-abl protein with those of protein kinase C, cyclic AMP-dependent protein kinase, and the activated c-raf protein.

In the present study, we have compared the mode of action of the v-abl protein in the regulation of gene expression with those of serine/threonine protein kinases such as protein kinase C, cyclic AMP-dependent protein kinase, and the activated c-raf protein, by measuring the transcriptional activity of the serum-response element, the 12-O-tetradecanoylphorbol-13-acetate (TPA)-response element, and the cyclic AMP-response element in NIH3T3 cells transfected with the v-abl gene. The results indicate that the v-abl protein stimulates the serum-response element and the TPA-response element, but not the cyclic AMP-response element, in a manner similar to that of the activated c-raf protein, but different from those of protein kinase C and cyclic AMP-dependent protein kinase.

Blood Physiological Phenomena↗
PubMed1990

[Large granular lymphocyte leukemia containing oligoclonal EB viral DNA].

A 32-year-old female was admitted to our hospital because of abdominal fullness, jaundice and pretibial edema in November, 1987. Leukocyte count of peripheral blood showed 13300/microliters with 84% leukemic cells and bone marrow was normocellular with 63.6% leukemic cells. Leukemic cells had azurophilic large granules with basophilic cytoplasm and positive for CD 2, OKIa 1, NKH-1 and negative for CD 3, CD 4, CD 8, CD 16. T cell receptor (TCR) genes for beta, gamma and delta chain and immunoglobulin heavy chain gene were in germ line configuration. These cells also had natural killer (NK) activity and antibody dependent cell mediated cytotoxicity (ADCC) activity. These observations suggested that they were derived from NK cell lineage. It is often difficult to demonstrate their clonalities in lymphoproliferative disorder of granular lymphocytes (LDGL). In the present case, the analysis of EBV genome using termini probe demonstrated polyclonal bands, while we found constant chromosome abnormalities; 47 XX, +3. From these observations, this case was considered to have several clones, and one of which could be detected by chromosome analysis. The analysis of EBV genome using termini probe may be useful to demonstrate their clonalities in LDGL in addition to conventional chromosome analysis.

Adult↗
PubMed1990

[Effect of combination therapy with carumonam and clindamycin on severe infections in patients with hematologic malignancies].

We evaluated the efficacy of a combination therapy with carumonam (CRMN) and clindamycin (CLDM) on severe infections in patients with hematologic malignancies. Fifty three patients were included in this study. The efficacy of the combination therapy was evaluated according to the criteria by TAKAKU et al. Fourteen cases were evaluated as excellent, and 24 cases were as good, with a total rate of effectiveness of 71.7% (38/53). It should be noted that the rate of effectiveness in patients having less than 100/microliters neutrophils was 77.3% (17/22). Adverse effects were observed in 2 patients (3.7%). One case was hepatotoxicity and the other was nephrotoxicity. Both were mild and transient, however. These observations suggested that the combination therapy with CRMN and CLDM was effective and safe for the treatment of severe infections in patients with hematologic malignancies.

Adult↗
PubMed1990

[Malignant lymphoma associated with Addison's disease].

A 62-year-old man was admitted to our hospital in Oct. 1986, because of easy fatigability, generalized pigmentation and lymph node swelling. Radiological examination showed massive adrenal tumor and two lung tumors. Endocrinological findings showed cortisol 8.3 micrograms/dl, aldosterone 35.3 ng/dl, ACTH 348 pg/ml, and non reacting pattern was observed in ACTH-overloading test, suggesting a presence of Addison's disease. A diagnosis of malignant lymphoma (Non-Hodgkin's lymphoma, diffuse large cell type) was made by lymph node biopsy, and radiotherapy to bulky bilateral adrenal tumors and cervical lymph nodes was performed with some response. Then, treatment with VEPA and PEP-VP regimens were carried out, and adrenal tumor became remarkably small in size. However, adrenal function did not recover. He relapsed in Jan. 1987 and died of multiple organ failure.

Addison Disease↗
PubMed1989

Activation of the serum response element and 12-O-tetradecanoylphorbol-13-acetate response element by the activated c-raf-1 protein in a manner independent of protein kinase C.

Transfection of the cDNA encoding the activated c-raf-1 protein or addition of 12-O-tetradecanoylphorbol-13-acetate (TPA) or dibutyryl cAMP to NIH/3T3 cells activated the c-fos gene enhancer linked to the chloramphenicol acetyltransferase or luciferase reporter gene. Prolonged treatment of NIH/3T3 cells with phorbol 12,13-dibutyrate caused down-regulation of protein kinase C. In these cells, addition of TPA did not stimulate the c-fos gene enhancer any more, but transfection of the c-raf-1 cDNA or addition of dibutyryl cAMP still stimulated the c-fos gene enhancer to the same extent as those induced in the control cells. Transfection of the c-raf-1 cDNA or addition of TPA to NIH/3T3 cells stimulated the serum response element and TPA response element but not the cAMP response element. In contrast, addition of dibutyryl cAMP to NIH/3T3 cells stimulated the cAMP response element but not the serum response element or TPA response element. These results indicate that the activated c-raf-1 protein stimulates the serum response element and TPA response element in a manner independent of protein kinase C and cAMP-dependent protein kinase. Since the c-fos gene enhancer has been shown to contain the serum response element and cAMP response element, it is most likely that the c-raf-1 protein is involved in the regulation of c-fos gene expression through the serum response element.

Animals↗
PubMed1989

Molecular genetic analysis of the regulatory and catalytic domains of protein kinase C.

We have constructed the expression plasmids harboring protein kinase C (PKC) mutant cDNAs with a series of deletions in the PKC coding region. These plasmids were transfected into COS7 cells to characterize the PKC mutants. Immunoblot analysis using the anti-PKC antibody identified proteins with the Mr values expected from the PKC mutant cDNAs in the extracts from COS7 cells. The wild-type PKC, when expressed in COS7 cells, conferred increased phorbol ester binding activity on intact cells; but the PKC mutants with the deletion around the C1 region did not show this activity. The wild-type PKC showed protein kinase activity dependent on phospholipid, Ca2+, and phorbol ester, whereas these PKC mutants exhibited protein kinase activity independent of the activators in a cell-free system. A PKC mutant cDNA with the deletion in the C2 region gave increased phorbol ester binding activity. Protein kinase activity of this mutant was much less dependent on Ca2+ compared with the wild-type PKC. A PKC mutant cDNA with the deletion in the C3 region conferred increased phorbol ester binding activity, but neither activator-dependent nor -independent protein kinase activity. These results indicate that elimination of the C1 region of PKC gives rise to constitutively active PKC independent of phospholipid, Ca2+, and phorbol ester and that the C1-C3 regions play distinct roles in the regulatory and catalytic function of PKC. In another series of experiments, transfection of some PKC mutant cDNAs with the deletions around the C1 region into Chinese hamster ovary and Jurkat cells activated the activator protein-1-binding element or the c-fos gene enhancer linked to the chloramphenicol acetyltransferase reporter gene in the absence of phorbol ester. Microinjection of these constructs into Xenopus oocytes induced initiation of germinal vesicle breakdown, indicating that they stimulated the PKC pathway in vivo. Thus, the phorbol ester-independent PKC mutant cDNAs could be a powerful tool to investigate the transmembrane signaling pathway mediated by PKC.

Amino Acid Sequence↗
PubMed1989

Possible role of prostaglandins as negative regulators in growth stimulation by tumor necrosis factor and epidermal growth factor in human fibroblasts.

Recombinant tumor necrosis factor (TNF), epidermal growth factor (EGF), and transforming growth factor beta (TGF-beta) stimulated growth of confluent human diploid fibroblasts (FS-4 cells) in the presence of fetal calf serum. TGF-beta synergistically enhanced both the TNF- and EGF-stimulated cell growth, whereas synergism between the mitogenic action of EGF and that of TNF was not observed. When indomethacin or acetylsalicylic acid, an inhibitor of prostaglandin production, was added to FS-4 cells, cell growth stimulated by EGF or TNF was increased, suggesting that prostaglandins induced by these mitogens antagonize their growth stimulatory actions. In contrast, neither indomethacin nor acetylsalicylic acid had a significant effect on the TGF-beta-induced growth of FS-4 cells. Mitogenic responses of indomethacin-treated cells to EGF, TNF, and TGF-beta were similarly suppressed by the addition of exogenous prostaglandin D2 (PGD2). Other prostaglandins such as PGE2 and PGF2 produced less inhibition of the cell growth.

Arachidonic Acids↗
PubMed1989

Tumor necrosis factor is cytotoxic to human fibroblasts in the presence of exogenous arachidonic acid.

Recombinant human tumor necrosis factor (TNF) stimulated the growth of confluent human fibroblasts (FS-4) in serum-free culture medium. However, TNF had a cytotoxic effect upon the growth of FS-4 cells in combination with arachidonic acid. When arachidonic acid was added to culture medium in the absence of TNF, however, it had no effect on the cell growth. Arachidonic acid inhibited the TNF-induced cell growth in a dose-dependent manner: it reversed the TNF-stimulated growth to the control level at a concentration of 10 microM and was cytotoxic to TNF-treated FS-4 cells at higher concentrations. This cytotoxicity of TNF was not observed in FS-4 cells treated with palmitic acid. Indomethacin, a cyclooxygenase inhibitor, decreased the cytotoxic effect that TNF exerted in the presence of arachidonic acid. These results suggest that TNF becomes cytotoxic to FS-4 cells when arachidonic acid present in the culture medium is converted to prostaglandins.

Arachidonic Acids↗
PubMed1989

Cancer chemotherapy administered by activated carbon particles and liposomes.

In cancer chemotherapy, a specific drug delivery system is expected since many anticancer drugs show toxicity against not only cancer cells but also against normal tissues. The dosage form comprising anticancer drugs adsorbed on activated carbon particles or encapsulated in liposomes is developed as a drug-delivery system which enhances the therapeutic efficacy and reduces the adverse effects. The dosage forms are versatile in size and electric charge, so that large amounts of the drugs are distributed to the "targeted" organs or tissues and lesser amounts are distributed to the whole body. The dosage forms are designed to release the drugs slowly for a long time at local sites. Through this process, practical use of the dosage forms as an anticancer drug carrier results in an enhancement of anticancer efficacy on the local lesion and a decrease of systemic toxicity.

Adjuvants, Immunologic↗
PubMed1989

Synthetic polycations, polyethylenimines and polyallylamines release histamine from rat mast cells.

The effects of synthetic polycations, which induce liposomal membrane fusion without inducing permeability changes, on histamine release from rat mast cells were investigated. Polyethylenimines and polyallylamines with various molecular weights released histamine from mast cells. Acetylated derivatives and triethylentetramine did not release histamine or serotonin from the cells. The histamine release induced by 10 micrograms/ml polyethylenimine with a molecular weight of 600 was inhibited by 1 mM dibutyryl cyclic AMP, but not by 1 MM 8-bromo cyclic GMP; 100 microM D-600, a calcium antagonist; or 30 microM W-7, a calmodulin inhibitor. In the presence of polyethylenimines with molecular weights of 600, 1,200 and 1,800, no detectable release of cytosolic lactate dehydrogenase was observed, indicating that histamine release induced by these polycations was not due to their cytotoxicity. The potencies of these polymers in inducing histamine release depended on their charges, but not on their degrees of polymerization. On the other hand, the actions of polyethylenimine with a molecular weight of 10,000 and polyallylamines with molecular weights of 3,000-4,000 and 10,000 in releasing lactate dehydrogenase were somewhat cytotoxic. These polycations did not induce serotonin release from rat platelets, suggesting that platelets have no coupling system of signal transduction by these polycations. Thus polycations seemed to interact with the mast cell membrane to induce histamine release, and the potencies of these polycations on mast cells seemed to differ from those of their effects on liposomes, which were examined previously.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1989

[Assessment of reproducibility of transcranial Doppler velocimetry].

In recent years, transcranial Doppler velocimetry has been widely used as a noninvasive method for measurement of blood flow velocity in basal cerebral arteries. As for the reproducibility of this method, however, there have been only few reports so far. In the present study, we attempted to evaluate the reproducibility of this method by changing the examiners and the timing of the examination. Fifteen healthy volunteers were investigated by using a pulsed wave Doppler ultrasound device with a 2 MHz transducer. Both peak and mean spatial frequencies calculated from the frequency spectrum of the Doppler signals from the middle cerebral artery (MCA) and the basilar artery (BA) were used as blood flow parameters for assessing the reproducibility. The arterial blood pressure and the end-tidal carbon dioxide partial pressure (PECO2) were also monitored during the ultrasonic examinations. The intra- and inter-observer reproducibilities were evaluated by obtaining the coefficient of variation (CV) of the differences and/or analyzing the correlation between the values from the two measurements by the same examiner and by two separate examiners, respectively. The intraobserver reproducibility in separate days was also evaluated. Both in the mean arterial blood pressure and in PECO2, no significant changes were observed between the two measurements in each subjects. In the present examination, the CV and r values ranged from 6.7 to 19.5% and from 0.69 to 0.95, respectively, showing good reproducibility of the transcranial Doppler method for measurement of blood flow velocity, though some differences were observed as follows. The intraobserver reproducibility was better than the interobserver reproducibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗