Biomedical subjects

S Ohkuma

Publications and source records attributed to S Ohkuma.

At least 19 recordsLinked to original sources

PubMed2006

Regression of papular elastolytic giant cell granuloma using narrow-band UVB irradiation.

A 71-year-old Japanese man presented with asymptomatic, firm, brown-red papules on the dorsum of his left hand and back. A biopsy specimen revealed granulomatous infiltration consisting of multinucleated giant cells and histiocytes in the upper dermis. Elastic fibers were absent in the upper dermis, having been phagocytosed by giant cells. These papular elastolytic giant cell granuloma lesions regressed very well with narrow-band ul traviolet B irradiation, with only residual brown pigmentation left after treatment.

Aged↗

PubMed2002

Influence of lipophilicity and lysosomal accumulation on tissue distribution kinetics of basic drugs: a physiologically based pharmacokinetic model.

This paper examines the role of lipophilicity in the tissue distribution kinetics of basic drugs. Basic drugs have a large distribution volume and are distributed widely in various tissues in the following order: lung, fat, heart, kidney, brain, gut, muscle and bone. The fat volume in the whole body influences the disposition kinetics. There is a good correlation in various tissues between the tissue-plasma concentration ratio and the octanol-water partition coefficient among various drugs. We constructed a physiologically-based pharmacokinetic model on the basis of drug lipophilicity and found that drug distribution decreased when NH4Cl was administered concomitantly. In regards to subcellular distribution, the relative specific contents of chlorpromazine, imipramine and biperiden with respect to the protein in lysosomes were 7.3, 9.6 and 4.2, respectively, while those in other subcellular organella, including mitochondria, were only 0.4-1.7, indicating preferential accumulation of these drugs in lysosomes. The uptake of basic drugs into lysosomes depended on both intralysosomal pH and drug lipophilicity. As the lipophilicity of the basic drugs increased, they accumulated more than would have been predicted from the pH-partition theory and raised the intralysosomal pH more potently, probably owing to their binding with lysosomal membranes, with or without intralysosomal aggregation. We conclude that the distribution kinetics of basic drugs is driven by drug lipophilicity and uptake into lysosomes, and these phenomena provide a possible basis for drug interaction in clinical treatments.

Animals↗

PubMed2001

Withdrawal from nicotine facilitates diazepam binding inhibitor mRNA expression in mouse cerebral cortex.

Changes in diazepam binding inhibitor (DBI) mRNA expression after withdrawal from nicotine were examined. Withdrawal from nicotine Increased DBI mRNA expression in cerebral cortices derived from nicotine-dependent mice and in the neurons continuously exposed to nicotine (0.1 microM). These results indicate that withdrawal from nicotine after its long-term exposure induces steep increase of DBI mRNA expression as reported previously in ethanol- and morphine-dependent animals.

Animals↗

PubMed2001

A simple estimation of peroxisomal degradation with green fluorescent protein - an application for cell cycle analysis.

When nutrients are depleted from the environment, mammalian cells begin to degrade their own cytosol and organelles. This bulk protein degradation is mediated by autophagy. In this study, peroxisomes in living CHO-K1 cells were visualized by targeting the green fluorescent protein (GFP) tagged with a type 1 peroxisomal targeting signal. The nutrient-starved condition induced a decay of GFP fluorescence in the peroxisomes and autophagic inhibitors such as 3-methyladenine suppressed the decay of GFP fluorescence (13-60% of starvation). By double labeling the nuclear DNA and peroxisomal GFP, the autophagy specifically occurred at the G1 phase of the cell cycle and the autophagic inhibitors suppressed the G1 arrest. The vital stain technique with GFP is a very simple and useful marker to quantitatively estimate or to further study peroxisomal degradation.

Animals↗

PubMed2001

Suppression of Ca2+ influx through L-type voltage-dependent calcium channels by hydroxyl radical in mouse cerebral cortical neurons.

In the present study, we investigated the effect of hydroxyl radical (.OH) produced by the Fenton reaction with FeSO(4) to H(2)O(2) on Ca2+ influx by measuring [(45)Ca2+] influx into mouse cerebral cortical neurons in primary culture.OH formed from 3 microM FeSO(4) and 0.01 microM H(2)O(2) significantly reduced 30 mM KCl-induced [(45)Ca2+] influx and this reduction was abolished by .OH scavengers such as N,N'-dimethylthiourea and mannitol. Nifedipine (1 microM), an inhibitor for L-type voltage-dependent Ca2+ channels (VDCCs) showed no additive effect on the reduction of the 30 mM KCl-induced [(45)Ca2+] influx, while the inhibitors for P/Q- and N-type VDCCs showed further suppression of the KCl-induced [(45)Ca2+] influx even in the presence of .OH. Bay k 8644, an activator of L-type VDCCs, dose-dependently stimulated [(45)Ca2+] influx, and this stimulation disappeared in the presence of nifedipine. Similarly, .OH also suppressed significantly [(45)Ca2+] influx induced by Bay k 8644. These inhibitory actions of .OH on the KCl- and Bay k 8644-induced [(45)Ca2+] influx were completely abolished by .OH scavengers. These results indicate that .OH has the activity to suppress Ca2+ influx through L-type VDCCs.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed2001

NMDA receptor activation enhances diazepam binding inhibitor and its mRNA expressions in mouse cerebral cortical neurons.

Effects of N-methyl-D-aspartate (NMDA) on diazepam binding inhibitor (DBI) and its mRNA expression in mouse cerebral cortical neurons were examined. A significant increase in DBI mRNA expression was observed 1 day after the exposure to 0.1 microM NMDA and the maximal expression occurred 2 days after the exposure, whereas transient exposure to 0.1 microM NMDA for 15 min, 1 and 3 h produced no changes in the expression. Similarly, no changes in the expression were found by the concomitant exposure to NMDA and MK-801, a NMDA receptor antagonist, for 72 h subsequent to the incubation with NMDA alone for 3 h. Such NMDA-induced increases in DBI mRNA expression were dose-dependently inhibited by MK-801. Moreover, neuronal DBI content significantly increased by treatment with NMDA, which was completely abolished by MK-801. These results indicate that continuous activation of NMDA receptors is an essential factor for increasing DBI expression in the neurons.

Animals↗

PubMed2001

Alterations in cerebral diazepam binding inhibitor expression in drug dependence: a possible biochemical alteration common to drug dependence.

Mechanisms for formation of drug dependence and expression of withdrawal syndrome have not fully clarified despite of huge accumulation of experimental and clinical data at present. Several clinical features of withdrawal syndrome are considered to be common among patients with drug dependence induced by different drugs of abuse. One of them is anxiety. Recent investigations have revealed that diazepam binding inhibitor (DBI), a peptide consisting of 87 amino acids with molecular weight of about 10 kDa, serves as an inverse agonist for benzodiazepine (BZD) receptors with endogenously anxiogenic potential. These lines of data suggest that cerebral DBI expression in brain may participates in formation of drug dependence and/or emergence of withdrawal syndrome. Based on this working hypothesis, we have examined DBI expression in the brain derived from mice depended on alcohol (ethanol), nicotine, and morphine to investigate functional relationship between cerebral DBI expression and drug dependence. Cerebral DBI expression significantly increases in animals with drug dependence induced by these drugs, and in the cases of nicotine- and morphine-dependent mice concomitant administration of antagonists for nicotinic acetylcholine and opioid receptors, respectively, abolished the increase. Abrupt cessation of administration of drugs facilitated further increase in DBI expression. Therefore, these alterations in DBI expression have close relationship with formation of drug dependence and/or emergence of withdrawal syndrome, and are considered to be a common biochemical process in drug dependence induced by different drugs of abuse. Finding and elucidation of mechanisms for common biochemical alterations among drug dependence may provide a clue to clarify mechanisms for formation of drug dependence and/or emergence of withdrawal syndrome.

Alcoholism↗

PubMed2001

Nitric oxide and peroxynitrite as factors to stimulate neurotransmitter release in the CNS.

This review summarizes the stimulatory potentials of NO and peroxynitrite (OONO-) on neurotransmitter release in the central nervous system. Exogenous and endogenous NO stimulates to release neurotransmitter. NO synthesized intracellularly diffuses out through neuronal membrane and acts on the outer side of membrane to depolarize neuronal membrane, which triggers neurotransmitter release. NO-induced release of neurotransmitters is mediated by Ca2+-dependent and -independent processes. The latter process is operated by reverse process of the Na+-dependent carrier-mediated neurotransmitter uptake system or by unknown mechanisms. Ca2+-dependent release of neurotransmitter occurs in part subsequent to increase in Ca2+ influx via VDCCs, although N-type VDCCs may not involve in this action of NO because of suppression of Ca2+ influx through N-type VDCCs by NO. Participation of cGMP formation by NO on neurotransmitter release is controversial. A superoxide scavenger, Ca2+, Zn(2+)-superoxide dismutase, abolishes NO-induced neurotransmitter release and synthesized OONO- induces neurotransmitter release, indicating that OONO- participates in NO-evoked neurotransmitter release.

Animals↗

PubMed2001

Peroxynitrite affects Ca2+ influx through voltage-dependent calcium channels.

The effect of peroxynitrite (OONO-) on voltage-dependent Ca2+ channels (VDCCs) was examined by measuring [45Ca2+] influx into mouse cerebral cortical neurones. OONO- time- and dose-dependently increased [45Ca2+] influx and this increase was abolished by manganese (III) tetrakis (4-benzoic acid) porphyrin, a scavenger for OONO-. Inhibition of cyclic GMP (cGMP) formation did not alter the OONO(-)-induced [45Ca2+] influx. OONO-, as well as 30 mm KCl, significantly increased fluorescence intensity of cell-associated bis-(1,3-dibutylbarbituric acid) trimethine oxonol (bis-oxonol). Tetrodotoxin and membrane stabilizers such as lidocaine dose-dependently suppressed OONO(-)-induced [45Ca2+] influx. Although each of 1 microM nifedipine and 1 microM omega-agatoxin VIA (omega-ATX) significantly inhibited the OONO(-)-induced [45Ca2+] influx and the concomitant presence of these agents completely abolished the influx, 1 microM omega-conotoxin GVIA (omega-CTX) showed no effect on the influx. On the other hand, OONO- itself reduced 30 mM KCl-induced [45Ca2+] influx to the level of [45Ca2+] influx induced by OONO- alone, and the magnitude of this reduction was as same as that of KCl-induced [45Ca2+] influx by omega-CTX. These results indicate that OONO- increases [45Ca2+] influx into the neurones through opening P/Q- and L-type VDCCs subsequent to depolarization, and inhibits the influx through N-type VDCCs.

Anesthetics, Local↗

PubMed2001

Recent research on alcohol tolerance and dependence.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Hiroshi Suwaki and Harold Kalant. The presentations were (1) Influence of ADH genotypes on acute alcohol withdrawal syndrome in Japanese, by Susumu Higuchi; (2) Use of genetic analyses to refine phenotypes related to alcohol tolerance and dependence, by John C. Crabbe; (3) Neurochemical basis for alcohol dependence, by Seitaro Ohkuma and Masashi Katsura; (4) Adenylyl cyclase and development of tolerance to addictive drugs, by Masami Yoshimura; (5) Tolerance in rat lines selectively bred for alcohol preference, by Robert C. Stewart and Ting-Kai Li; and (6) Ethanol reinforcement, dependence, and vulnerability to relapse: Interactions between neuroadaptive and conditioning factors, by Friedbert Weiss.

Alcohol Dehydrogenase↗

PubMed2001

[Studies on the mechanism of subcellular distribution of basic drugs based on their lipophilicity].

This paper described the studies on the mechanism of subcellular distribution of lipophilic weak bases. Although the tissue distribution of basic drugs appeared to decrease with time simply in parallel with their plasma concentration, their subcellular distribution in various tissues exhibited a variety of patterns. Basic drugs were distributed widely in various tissues, but were concentrated in lung granule fraction, where their accumulation was dependent on their lipophilicity and lysosomal uptake. As the plasma concentration of drugs decreased after maximum level, the contribution of lysosomes to their subcellular distribution increased. The uptake of the basic drugs into lysosomes depended both on their intralysosomal pH and on the drug lipophilicity. As the lipophilicity of the basic drugs increased, they accumulated more than the values predicted from the pH-partition theory and raised the intralysosomal pH more potently, probably owing to their binding with lysosomal membranes with or without additional intralysosomal aggregation. These phenomena should be considered as a basis of drug interaction in clinical treatments.

Animals↗

PubMed2001

Presence of Vicia graminea or Vicia unijuga lectin-binding (Vgu) glycoproteins with and without Thomsen-Friedenreich (T) antigen in normal human seminal plasma.

Vgu glycoprotein (Vicia graminea lectin- or Vicia unijuga lectin-binding glycoprotein) has been reported as oncofetal antigen, which is found in many kind of tumor tissues, amniotic fluid and fetal membranes. In autoradiography with an 125I-labeled Vicia unijuga lectin (VUA) probe and an 125I-labeled Arachis hypogaea lectin (PNA, anti-T lectin) probe, seminal plasma samples of eight healthy men gave 2-7 Vgu glycoproteins without T antigen, 1-2 Vgu glycoproteins with Thomsen-Friedenreich antigen (T antigen) and 1-8 T-antigen glycoproteins, respectively. These results show that in addition to T-antigen glycoproteins, normal human seminal plasma contains Vgu glycoproteins and Vgu glycoproteins with T antigen as seminal plasma components as well as other tumor markers such as CA19-9, CA-125 and CEA.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed2000

Reversible and potent uncoupling of hog gastric (H(+)+K(+))-ATPase by prodigiosins.

Prodigiosin, prodigiosin 25-C, and metacycloprodigiosin all strongly inhibited the acidification activity of (H(+)+K(+))-ATPase on membrane vesicles from hog gastric mucosa (IC(50) = 32 to 103 pmol/mg protein). But, the prodigiosins, unlike omeprazole, showed little inhibitory effect on K(+)-dependent ATPase (K(+)-ATPase) activity, although at higher concentrations they inhibited K(+)-ATPase activity with an IC(50) of 1.5 to 3.0 microM. Furthermore, the inhibitory effect of the prodigiosins was rapid and completely reversible unlike that of omeprazole, and the mode of inhibition was non-competitive with respect to ATP. Hog gastric (H(+)+K(+))-ATPase itself showed an absolute requirement of halide (effectively, chloride) for acidification activity. Prodigiosins also showed a chloride requirement for inhibition of vesicular acidification, and quickly reversed the acidification of vesicular pH to neutrality even in the presence of N, N'-dicyclohexylcarbodiimide (DCCD), showing their ionophoric nature of acidification inhibitory activity. In fact, tributyltin chloride (TBT, an OH(-)/Cl(-) exchange ionophore) also inhibited vesicular acidification, but it inhibited K(+)-ATPase activity too. Finally, the prodigiosins inhibited the acid secretion from parietal cells isolated from rabbit gastric mucosa. These results suggest that prodigiosins are potent reversible uncouplers of (H(+)+K(+))-ATPase that inhibit gastric acid secretion.

Adenosine Triphosphate↗

PubMed2000

Vacuolar H(+)-ATPase plays a crucial role in growth and phenotypic modulation of myofibroblasts in cultured human saphenous vein.

BACKGROUND: The molecular mechanism of neointimal hyperplasia after vein graft surgery remains elusive. Vacuolar H(+)-ATPase (V-ATPase) is involved in intracellular trafficking and may play a crucial role in neointimal cell growth. METHODS AND RESULTS: Cultured human saphenous vein segments developed neointimal formation within 10 days. Neointimal cells were positive for vimentin and alpha-smooth muscle actin but negative for desmin, which is indicative of myofibroblasts. Those myofibroblasts were found to have originated from periadventitial fibroblasts, which upregulated the expression of 16-kDa proteolipid of V-ATPase before proliferation and phenotypic modulation. Neointimal myofibroblast growth and survival were highly sensitive to inhibition of V-ATPase by bafilomycin A(1) (BA(1)), because the incorporation of [(3)H]thymidine into the myofibroblasts was significantly inhibited by nanomolar concentrations of BA(1) and apoptotic cell death was induced by a similar concentration range of BA(1). In contrast, endothelial cells and differentiated smooth muscle cells were resistant to apoptosis by BA(1). CONCLUSIONS: These results suggest that V-ATPase plays a crucial role in growth and phenotypic modulation of myofibroblasts that contributes to neointimal formation in cultured human saphenous vein.

Adult↗

PubMed2000

Mechanism for increase in expression of cerebral diazepam binding inhibitor mRNA by nicotine: involvement of L-type voltage-dependent calcium channels.

We investigated the mechanisms underlying the increase in diazepam binding inhibitor (DBI) and its mRNA expression induced by nicotine (0.1 microM) exposure for 24 h using mouse cerebral cortical neurons in primary culture. Nicotine-induced (0.1 microM) increases in DBI mRNA expression were abolished by hexamethonium, a nicotinic acetylcholine (nACh) receptor antagonist. Agents that stabilize the neuronal membrane, including tetrodotoxin (TTX), procainamide (a Na(+) channel inhibitor), and local anesthetics (dibucaine and lidocaine), dose-dependently inhibited the increased expression of DBI mRNA by nicotine. The nicotine-induced increase in DBI mRNA expression was inhibited by L-type voltage-dependent Ca(2+) channel (VDCC) inhibitors such as verapamil, calmodulin antagonist (W-7), and Ca(2+)/calmodulin-dependent protein kinase II (CAM II kinase) inhibitor (KN-62), whereas P/Q- and N-type VDCC inhibitors showed no effects. In addition, nicotine exposure for 24 h induced [3H]nicotine binding to the particulate fractions of the neurons with an increased B(max) value and no changes in K(d). Under these conditions, the 30 mM KCl- and nicotine-induced 45Ca(2+) influx into the nicotine-treated neurons was significantly higher than those into non-treated neurons. These results suggest that the nicotine-stimulated increase in DBI mRNA expression is mediated by CAM II kinase activation resulting from the increase in intracellular Ca(2+) through L-type VDCCs subsequent to the neuronal membrane depolarization associated with nACh receptor activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2000

V-Type H+-ATPase/synthase from a thermophilic eubacterium, Thermus thermophilus. Subunit structure and operon.

V-type ATPase (V(o)V(1)) capable of ATP-driven H(+) pumping and of H(+) gradient driven ATP synthesis was isolated from a thermophilic eubacterium, Thermus thermophilus. When the enzyme was analyzed by gel electrophoresis in the presence of sodium dodecyl sulfate, it showed eight polypeptide bands of which four were subunits of V(1). We also isolated the V(o)V(1) operon, containing nine genes in the order of atpG-I-L-E-X-F-A-B-D, which encoded proteins with molecular sizes of 13, 43, 10, 20, 35, 11, 64, 53, and 25 kDa, respectively. The last four genes were identified as those for V(1) subunits; atpA, B, D, and F encoded the A, B, gamma, and delta subunits, respectively. The first five genes, atpG-atpX, were identified as genes for the V(o) subunits. The product of atpL, the proteolipid subunit, lacked a 19-amino acid presequence and, unlike V-type ATPases, contained two membrane-spanning domains rather than four. The hydrophobic 43-kDa product of atpI is the smallest member so far found of the eukaryotic 100-kDa subunit family. Its electrophoretic band overlapped with the band of the A subunit. Therefore, all the gene products were found in our purified V(o)V(1). We isolated the A(3)B(3) subcomplex reconstituted from the isolated subunits and the A(3)B(3)gamma subcomplex from subunit-expressing Escherichia coli. Electron microscopic observation of these subcomplexes revealed that the gamma subunit of V(1) filled the central cavity of A(3)B(3) and might be central subunit, similar to the gamma subunit of F(1)-ATPase.

Amino Acid Sequence↗

PubMed2000

Potential role of vacuolar H-adenosine triphosphatase in neointimal formation in cultured human saphenous vein.

OBJECTIVE: Vacuolar H(+)-adenosine triphosphatase plays a pivotal role in pH regulation and molecular transport across the vacuolar membranes and is involved in cell proliferation and transformation. In the present study, possible involvement of vacuolar H(+)-adenosine triphosphatase in neointimal formation was investigated in an organ culture model of human saphenous vein. METHODS AND RESULTS: Cultured saphenous vein segments developed neointimal formation and marked thickening of the media within 14 days. Neointimal formation and medial thickening were completely inhibited by 10 nmol/L bafilomycin A(1), a selective inhibitor of vacuolar H(+)-adenosine triphosphatase, although structurally related macrolide antibiotics FK-506 and erythromycin were without an effect. The neointimal cells were positive for alpha-smooth muscle actin and vimentin but negative for desmin, indicative of myofibroblasts. The emergence of myofibroblasts was inhibited, and endothelial cells were preserved in the saphenous vein segments treated with bafilomycin A(1). Uptake of bromodeoxyuridine, a proliferation marker, by myofibroblasts was abrogated in the saphenous vein segments treated with 10 nmol/L bafilomycin A(1). Detection of apoptotic cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling concomitant with identification of desmin-expressing smooth muscle cells demonstrated that neointimal myofibroblasts, but not medial smooth muscle cells, that expressed desmin underwent apoptosis by treatment with bafilomycin A(1). CONCLUSIONS: These results suggest that vacuolar H(+)-adenosine triphosphatase may be involved in myofibroblast growth that contributes to neointimal formation and medial thickening in cultured human saphenous vein. Increased sensitivity of myofibroblasts, but not endothelial cells, and differentiated smooth muscle cells to bafilomycin A(1) may have potential therapeutic implications in the treatment for vein graft disease.

Actins↗

PubMed2000

Simultaneous monitoring of conditioned place preference and locomotor sensitization following repeated administration of cocaine and methamphetamine.

The paradigm of conditioned place preference has been widely used to demonstrate the rewarding properties of psychomotor stimulants. Such drugs also stimulate locomotor activity. Repeated administration of low doses of psychomotor stimulants causes progressive increases in the locomotor stimulating effect, a phenomenon termed behavioral sensitization. Using a new activity monitor (SCANET MV-10LD) that simultaneously measures the amount of time spent and the distance traveled in each side of a two-compartment chamber, the present study assessed place preference conditioning and locomotor sensitization following repeated administration of cocaine or methamphetamine (MAP) in mice. We examined the effect of environmental factors on these activities using two different types of chamber: one having a single cue, and the other having dual cues for the discrimination of compartments. In both types of chamber, cocaine (5-20 mg/kg) and MAP (1-2 mg/kg) similarly produced conditioned place preference. However, repeated cocaine administration caused the development of locomotor sensitization only in the single-cue chamber. On the other hand, repeated administration of MAP resulted in the development of sensitization in both types of chamber. The findings indicate that environmental factors differentially affect the development of locomotor sensitization, but not place preference conditioning, following repeated administration of cocaine or methamphetamine. The advantages of this new system will be discussed.

Animals↗