Biomedical subjects

S Kitayama

Publications and source records attributed to S Kitayama.

At least 19 recordsLinked to original sources

PubMed2005

Structure-activity relationship of trihexyphenidyl analogs with respect to the dopamine transporter in the on going search for a cocaine inhibitor.

A series of trihexyphenidyl (THP) analogs were used to search for a derivative that could serve as a cocaine inhibitor. A compound that blocks binding of the cocaine analog carboxyfluorotropane (CFT), allows dopamine uptake and exhibits low side effects could serve as a good candidate for that purpose. All analogs were tested for the extent to which they inhibit CFT binding, dopamine uptake and n-methyl scopolamine (NMS) binding. Several structure-function relationships emerged. Methylation/halogenation of THP's benzene ring enhanced the compound's ability to block CFT binding in comparison to its ability to block dopamine uptake (5a-e). Replacement of the cyclohexyl ring with a benzene ring tended to create compounds that had lower affinities to the dopamine transporter (7b compared to THP, 7d compared to 5h, 7c compared to 8c) and modification of THP's piperidine ring tended to enhance affinity to the dopamine transporter (5f-h, 8a, 8c). One analog (5f) that showed little muscarinic activity indicating that it would probably have few side effects was investigated for its effects as an in vivo cocaine inhibitor. However, it showed few antagonistic effects in vivo. Nevertheless, this work greatly elucidates the structure-function relationships required for potential cocaine inhibitors and so lays out promising directions for future research.

Carbonic Anhydrase Inhibitors↗

PubMed2004

Transport of dopamine and levodopa and their interaction in COS-7 cells heterologously expressing monoamine neurotransmitter transporters and in monoaminergic cell lines PC12 and SK-N-SH.

The present study investigated the effects of levodopa, a precursor of dopamine (DA) therapeutically used for the treatment of Parkinson's disease, on DA transport in the two different systems, COS-7 cells heterologously expressing rat monoamine transporter cDNA and in monoaminergic cell lines PC12 and SK-N-SH. Levodopa enhanced uptake of [3H]DA and [3H]norepinephrine (NE) but not [3H]serotonin in the transfected COS-7 cells in a concentration-dependent manner. On the other hand, in PC12 and SK-N-SH cells where NET is functionally expressed, levodopa enhanced [3H]DA and [3H]NE uptake at low concentrations and inhibited the uptake at higher concentrations. The effects of levodopa on catecholamine transporters in the opposite direction suggest a different mechanism at the intra- and extracellular sites in a levodopa transport-dependent and independent manner.

Animals↗

PubMed2001

Functional characterization of the splicing variants of human norepinephrine transporter.

Human norepinephrine transporter (NET) displays three splicing variants having different carboxy terminals, hNET, hNET C-t var1 and hNET C-t var2. Functional characterization of these isoforms was performed with transient expression system in COS-7 cells. Cells transfected with hNET C-t var2, but not hNET C-t var1, revealed a significant increase in [(3)H]norepinephrine (NE) uptake and [(3)H]nisoxetine binding as well as hNET, in association with their different cellular localization indicated by immunostaining using NET-specific antisera. Kinetic and pharmacological analyses of [(3)H]NE uptake revealed different characteristics between hNET and hNET C-t var2. These results suggest that hNET C-t var2 may participate in NE transport in a manner different from hNET at noradrenergic synapses or in other tissues including placenta where NET variants were found to exist.

Adrenergic Uptake Inhibitors↗

PubMed2001

Effects of volatile and intravenous anesthetics on the uptake of GABA, glutamate and dopamine by their transporters heterologously expressed in COS cells and in rat brain synaptosomes.

Although the neurotransmitter uptake system is considered a possible target for the presynaptic action of anesthetic agents, observations are inconsistent concerning effects on the transporter and their clinical relevance. The present study examined the effects of volatile and intravenous anesthetics on the uptake of GABA, glutamate and dopamine in COS cells heterologously expressing the transporters for these neurotransmitters and in the rat brain synaptosomes. Halothane and isoflurane, but not thiamylal or thiopental, significantly inhibited uptake by COS cell systems of GABA, dopamine and glutamic acid in a concentration-dependent manner within clinically relevant ranges for anesthesia induced by these agents. Similarly, in synaptosomes halothane and isoflurane but not thiopental significantly suppressed the uptake of GABA and glutamic acid, respectively. These results do not support the hypothesis that volatile and intravenous anesthetics exert their action via specific inhibition of GABA uptake to enhance inhibitory GABAergic neuronal activity. Rather, they suggest that presynaptic uptake systems for various neurotransmitters including GABA may be the molecular targets for volatile anesthetic agents.

ATP-Binding Cassette Transporters↗

PubMed2001

Nerve growth factor down-regulates the expression of norepinephrine transporter in rat pheochromocytoma (PC12) cells.

Functional expression of norepinephrine transporter (NET) and its regulation were examined in rat pheochromocytoma cell line, PC12. Nerve growth factor (NGF) decreased [3H]-norepinephrine (NE) uptake in association with a decrease in NET mRNA levels. On the other hand, levels of tyrosine hydroxylase mRNA increased in PC12 cells treated with NGF for 4-24 h, while Oct-2 mRNA levels decreased at 4 h with NGF then recovered for 8-24 h in the presence of NGF. Both bFGF and EGF reduced [3H]NE uptake, although they failed to affect NET mRNA levels. To examine the NET transcriptional regulation, we identified the 5'-noncoding region of rat NET mRNA by the rapid amplification of cDNA end (RACE) method and cloned the 5'-flanking region of NET gene. The newly identified exon encodes the untranslated region of rat NET mRNA upstream of the known 5'-region including ATG start codon. Constructs having green fluorescent protein (GFP) as reporter were made with the cloned NET gene, and promoter activity was examined in CHO and SK-N-SH cells transiently transfected and in PC12 cells stably transfected with NET-GFP constructs. The results indicate that the 2.1 kb NET flanking region displays promoter activity and is responsible for the NGF-induced down-regulation of NET expression.

5' Untranslated Regions↗

PubMed2001

Differential effects of trihexyphenidyl on place preference conditioning and locomotor stimulant activity of cocaine and methamphetamine.

Cocaine produces rewarding and locomotor stimulant effects by increasing extracellular dopamine (DA) levels in the terminal areas of the mesolimbic DA system. Our recent in vitro studies have shown that a muscarinic receptor antagonist, trihexyphenidyl (THP) inhibits the binding of a cocaine analogue to the DA transporter at concentrations that are ineffective in inhibiting 3H-DA uptake, suggesting that THP may attenuate the actions of cocaine selectively. The present study examined whether THP could affect conditioned place preference (CPP) for and locomotor stimulant activity of cocaine and methamphetamine (MAP) in mice. Mice were injected with cocaine (10 mg/kg) or MAP (1 mg/kg) in one compartment of the CPP chamber 4 times every second day. On alternate days the animals received saline in the other compartment of the CPP chamber. Pretreatment with THP was made 10 min before cocaine or MAP injection. The CPP score and locomotor activity were assessed using a novel activity monitor, SCANET. Cocaine and MAP produced CPP for the drug-paired compartment. Pretreatment with THP (0.05-5 mg/kg) had no influence on cocaine-induced CPP at any dose tested. In contrast, MAP-induced CPP was completely antagonized by THP at 5 mg/kg, which produced no CPP by itself. Another muscarinic receptor antagonist, scopolamine (SCP, 3 mg/kg) neither caused CPP by itself nor affected the development of cocaine- or MAP-induced CPP. Both THP and SCP enhanced spontaneous, cocaine- or MAP-induced locomotor activity. Though the present conditioning treatments failed to develop locomotor sensitization to cocaine, THP, but not SCP, acted cooperatively with cocaine to develop locomotor sensitization. The development of locomotor sensitization to MAP was retarded by SCP but was not affected by THP. These results suggest that, contrary to our anticipation, THP has a unique characteristic of specifically counter-acting the rewarding properties of MAP via a non-cholinergic (muscarinic) mechanism.

Animals↗

PubMed2001

[Development and validation of a sympathy scale].

The authors developed a 22-item scale of interpersonal sympathy that is informed by relevant practices and meanings of contemporary Japanese cultural context. In three independent samples the scale was shown to be reasonably reliable (alpha > .80). Furthermore, the scale had a systematic relationship with related variables, hence exhibiting satisfactory construct validity. Specifically, sympathy was positively correlated with both a reported frequency of prosocial behaviors (Study 1) and emotional empathy (Study 2). Moreover, sympathy formed a higher-order factor with interdependent construal of self, which was orthogonal to another higher-order factor comprised of independent construal of self and self-esteem (Study 3). Finally, some directions for future research are discussed.

Emotions↗

PubMed2001

Divergent consequences of success and failure in japan and north america: an investigation of self-improving motivations and malleable selves.

Self-enhancing and self-improving motivations were investigated across cultures. Replicating past research, North Americans who failed on a task persisted less on a follow-up task than those who succeeded. In contrast, Japanese who failed persisted more than those who succeeded. The Japanese pattern is evidence for a self-improving orientation: Failures highlight where corrective efforts are needed. Japanese who failed also enhanced the importance and the diagnosticity of the task compared with those who succeeded, whereas North Americans did the opposite. Study 2 revealed that self-improving motivations are specific to the tasks on which one receives feedback. Study 3 unpackaged the cultural differences by demonstrating that they are due, at least in part, to divergent lay theories regarding the utility of effort. Study 4 addressed the problem of comparing cultures on subjective Likert scales and replicated the findings with a different measure.

Creativity↗

PubMed2000

Mutation in recR gene of Deinococcus radiodurans and possible involvement of its product in the repair of DNA interstrand cross-links.

We previously reported that some Deinococcus radiodurans mutants are sensitive to DNA interstrand cross-linking agents but resistant to UV and gamma-rays. We isolated DNA fragments from a D. radiodurans genomic library which complemented the mitomycin C sensitivity of one of these mutants. One 3.2kb-long fragment contains an open reading frame of approximately 700bp and the deduced amino acid sequence is very homologous to other prokaryotic RecR proteins. This open reading frame in the mitomycin C-sensitive mutant strain contains a frame shift mutation at its carboxyl terminal region. These data suggest that RecR protein plays an important role in the resistance to interstrand cross-links in this bacterium.

Amino Acid Sequence↗

PubMed2000

Regulation of the development of allodynia by intrathecally administered P2 purinoceptor agonists and antagonists in mice.

Effects of agonists and antagonists of P2X-purinoceptors on the regulation of the development of allodynia were examined in mice; the drugs were administered intrathecally to the spinal cord. Suramin (5, 10 microg) and pyridoxalphosphate-6-azophenyl-2', 4'-disulfonic acid (PPADS), antagonists of P2X receptors, inhibited prostaglandin (PG) E(2)-induced allodynia. PPADS did not block glutamate-induced allodynia. alpha,beta-Methylene ATP (alpha, beta-meATP), an agonist of P2X receptor, elicited allodynia. alpha, beta-me ATP-induced allodynia was blocked by co-administration of alpha,beta-meATP with PPADS, MK 801 or N(omega)-nitro-L-arginine methyl ester (L-NAME). Suramin at higher doses (20, 40 microg) induced allodynia, which was inhibited by MK 801 or L-NAME. These results suggest that ATP P2X receptors in the spinal cord are involved in the regulation of tactile allodynia. Glutamate receptor and nitric oxide systems play an important role in the development of allodynia produced by alpha,beta-meATP and suramin.

Adenosine Triphosphate↗

PubMed2000

Selective inhibition of monoamine neurotransmitter transporters by synthetic local anesthetics.

Synthetic local anesthetics (LAs) have been found to have cocaine-like characteristics with some psychotomimetic action, possibly through monoaminergic neurotransmission. To gain insight into the relation between LA action and monoamine transporters, we investigated the effect of synthetic LAs on neurotransmitter transporters, including monoamine transporters. We used cloned transporter cDNAs and examined transient functional expression in COS cells and stable expression in HeLa cells. Among the LAs tested, procaine and other ester-type LAs inhibited [3H]DA uptake and binding of [3H]2-beta-carbomethoxy-3-beta-(4-fluorophenyl)tropane (CFT), a cocaine analogue, in COS cells expressing rat dopamine transporter (DAT). The inhibition was concentration-dependent. The inhibitory effect on [3H]DA uptake was reversible and not dependent on pH, as observed in HeLa cells stably expressing DAT. Procaine also inhibited uptake of norepinephrine (NE) and serotonin (5-HT) by the norepinephrine transporter (NET) or serotonin transporter (SERT) expressed in COS cells. On the other hand, procaine and other LAs had little or no effect on [3H]GABA and [3H]glutamate uptake in COS cells expressing mouse GABA or rat glutamate/aspartate transporter. IC50 values for [3H]DA uptake inhibition correlated well with those for [3H]CFT binding inhibition, but not with intrinsic anesthetic potency. Kinetic analysis of monoamine uptake inhibition by procaine in COS cells expressing rat DAT, NET or SERT revealed a competitive action similar to that of cocaine. These results demonstrate that certain LAs selectively inhibit monoamine transporters. This might contribute to the cocaine-like psychotomimetic action of certain LAs.

Anesthetics, Local↗

PubMed2000

Mediation by platelet-activating factor of 12-hydroxyeicosatetraenoic acid-induced cytosolic free calcium concentration elevation in neutrophils.

12(R)-hydroxyeicosatetraenoic acid (HETE) shows biphasic increase in cytosolic free calcium concentration ([Ca2+]i) in rabbit and human neutrophils; the initial transient phase and the continuous falling phase. 12(S)-HETE was less potent in both species. BN50739, a platelet-activating factor (PAF) receptor antagonist, inhibited both phases of 12(R)-HETE-induced [Ca2+]i rise but did not affect leukotriene B4 (LTB4)-induced [Ca2+]i rise. N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), a PAF synthesis inhibitor, and manoalide, a phospholipase A2 inhibitor, reduced 12(R)-HETE-induced [Ca2+]i rise. These blockers inhibited the continuous phase of [Ca2+]i rise induced by N-formyl-methionyl-leucyl-phenylalanine (FMLP) with little effect on the initial phase. It had no significant effect on LTB4-induced [Ca2+]i rise. SC-41930, a LTB4-receptor antagonist, did not block 12-HETE-induced [Ca2+]i rise. In 12(R)-HETE-, FMLP- and LTB4-stimulated cells, accumulations of cell-associated PAF and released PAF were detected but not in unstimulated cells. BN50739 did not affect the accumulation of cell-associated PAF and release of PAF in 12(R)-HETE-stimulated cells. These results suggest that 12(R)-HETE-induced and partially, FMLP-induced, but not LTB4-induced [Ca2+]i rise are mediated by PAF, which is produced and released by stimulation of the cells by 12(R)-HETE and FMLP, respectively.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed2000

Changes in seizure susceptibility to local anesthetics by repeated administration of cocaine and nomifensine but not GBR12935: possible involvement of noradrenergic system.

We examined cross-sensitization of cocaine and synthetic local anesthetics to their seizure susceptibility after repeated administration. Seizure susceptibility of procaine and lidocaine increased after the end of two days of treatment with a subconvulsive dose of cocaine. Acute treatment with nomifensine but not GBR12935, a specific inhibitor of the dopamine transporter, facilitated lidocaine-induced convulsion. Furthermore, daily treatment with nomifensine for two days enhanced lidocaine-induced convulsion. These results suggest the possible involvement of the brain noradrenergic system in the changes in seizure susceptibility after repeated administration of some local anesthetics.

Anesthetics, Local↗

PubMed2000

Dopamine transporter transmembrane domain polar mutants: DeltaG and DeltaDeltaG values implicate regions important for transporter functions.

Polar residues in dopamine transporter (DAT) transmembrane domains (TMs) are likely to act individually and even interactively in recognizing cocaine and dopamine. We initially evaluated the effects of alanine substitution mutants that remove the polar side chains from residues in each of the 12 putative DAT TMs on the recognition of dopamine and the cocaine analog CFT. Eleven combination mutants with multiple substitutions in DAT TMs 4, 5, 7, or 11 were then selected as candidates for more detailed evaluation based on mutation effects on dopamine and cocaine analog affinities. An evaluation of Gibbs free energy changes displayed by single and combined TM mutants (DeltaG(o) and DeltaDeltaG(o)(int)) reveals three categories of potential interactions among mutants: 1) independent, noncooperative interactions (five influenced CFT and two influenced dopamine affinities), 2) synergistic influences (two for CFT and four for dopamine), and 3) complementation of influences on CFT recognition (four mutants) or on dopamine affinity (five). Combined mutations in TMs 4 and 5 yield the largest DeltaDeltaG(o)(int) values for dopamine uptake. TMs 4 and 11 mutants provide the largest DeltaDeltaG(o)(int) for CFT binding. Interactions between residues lying in DAT TMs 4 and 5 support current DAT structural models that suggest the juxtaposition of these two TMs. These data also support contributions of TM 4 and 11 residues to a polar pocket important for cocaine recognition. These candidate interactive DAT polar domains provide larger target sites for compounds that could modulate specific DAT functions than those provided by single mutations alone.

Alanine↗

PubMed2000

Psychological and physical reactions on children after the Hanshin-Awaji earthquake disaster.

Children who experienced the Hanshin-Awaji Earthquake Disaster were followed to ascertain how the psychological and physical reactions after this disaster changed. Changes observed in the symptoms of children at one and two years after the earthquake were compared between those who had lived in severely damaged area (level 7 on the Japan Meteorological Agency intensity scale) and those who had lived in mildly damaged area (less than 5 on the same scale). The survey was conducted using a questionnaire filled out by the children's parents. Two years after the earthquake, the children had returned to normal in terms of their physical conditions, even in the severely damaged area. However, symptoms of PTSD (Post-Traumatic Stress Disorder) such as persistent reexperiencing, persistent avoidance, and increased arousal were significantly more frequently found among children from the severely damaged area than among those from the mildly damaged area. To evaluate the psychological and physical reactions after the disaster is very important in order to support the children when large-scale disasters occur.

Age Distribution↗

PubMed1999

Molecular analysis of the Deinococcus radiodurans recA locus and identification of a mutation site in a DNA repair-deficient mutant, rec30.

Deinococcus radiodurans strain rec30, which is a DNA damage repair-deficient mutant, has been estimated to be defective in the deinococcal recA gene. To identify the mutation site of strain rec30 and obtain information about the region flanking the gene, a 4.4-kb fragment carrying the wild-type recA gene was sequenced. It was revealed that the recA locus forms a polycistronic operon with the preceding cistrons (orf105a and orf105b). Predicted amino acid sequences of orf105a and orf105b showed substantial similarity to the competence-damage inducible protein (cinA gene product) from Streptococcus pneumoniae and the 2'-5' RNA ligase from Escherichia coli, respectively. By analyzing polymerase chain reaction (PCR) fragments derived from the genomic DNA of strain rec30, the mutation site in the strain was identified as a single G:C to A:T transition which causes an amino acid substitution at position 224 (Gly to Ser) of the deinococcal RecA protein. Furthermore, we succeeded in expressing both the wild-type and mutant recA genes of D. radiodurans in E. coli without any obvious toxicity or death. The gamma-ray resistance of an E. coli recA1 strain was fully restored by the expression of the wild-type recA gene of D. radiodurans that was cloned in an E. coli vector plasmid. This result is consistent with evidence that RecA proteins from many bacterial species can functionally complement E. coli recA mutants. In contrast with the wild-type gene, the mutant recA gene derived from strain rec30 did not complement E. coli recA1, suggesting that the mutant RecA protein lacks functional activity for recombinational repair.

Amino Acid Sequence↗

PubMed1999

Identification and disruption analysis of the recN gene in the extremely radioresistant bacterium Deinococcus radiodurans.

We isolated a radiosensitive mutant strain, KR4128, from a wild-type strain of Deinococcus radiodurans, which is known as a extremely radioresistant bacterium. The gene that restore the defect of the mutant in DNA repair was cloned, and it turned out to be the homolog of the recN gene of Escherichia coli. The recN gene encoded a protein of 58 kDa, and, in its N-terminal region, a potential ATP binding domain was conserved as expected for a prokaryotic RecN protein. An analysis of sequence of the mutant recN gene revealed a G:C to T:A transversion near the 3' end of the coding region. This alteration causes an ochre mutation, and results in the truncation of 47 amino acids from the C-terminal region of the RecN protein. The null mutant of recN gene was constructed by insertional mutagenesis, and it showed substantial sensitivities to various types of DNA damaging agents, indicating that a single defect in the recN gene can directly affect the DNA damage resistant phenotype in D. radiodurans. The recN locus of KR4128 was also disrupted and the disruptant indicated the sensitivity that was indistinguishable from its progenitor. The result indicate that the transversion in the recN gene of KR4128 cells causes a complete loss of function of the RecN protein and thus the C-terminal region of the RecN protein includes domain essential to its function.

Amino Acid Sequence↗

PubMed1999

Removal of Aromatic Hydrocarbon Compounds by Hydroxypropyl-cyclodextrin.

Activated carbon has been used for the recovery and removal of benzene, toluene, and xylenes in air and water for a long time. However, removal of benzene, toluene, and xylenes from soil is very difficult. They can be removed by an increase in the apparent solubility of organic compounds in soil. The apparent solubilities of benzene, toluene, and xylene were investigated to estimate their inclusion behavior into natural cyclodextrins (CDs) and hydroxypropyl-cyclodextrins (HP-CDs) in the liquid phase. The apparent solubilities of benzene, toluene, and xylenes did not increase by adding natural CDs but did increase when HP-CDs were added. Benzene, toluene, and xylenes in a HP-CD solution depended on the relationship between the molecular diameter of benzene, toluene, and xylenes, the CD cavity size, and the 1-octanol-water partition coefficient. That of p-xylene was larger than that of o-xylene and m-xylene because of the smallest steric hindrance of p-xylene. Copyright 1999 Academic Press.

Journal Article↗