Search PubMed⌕ Search

Biomedical subjects

Kenji Maeda

Publications and source records attributed to Kenji Maeda.

At least 19 recordsLinked to original sources
PubMed2006

Factors contributing to sleep disturbance and hypnotic drug use in hemodialysis patients.

OBJECTIVE: Sleep disturbance and the use of hypnotic medications are common in patients on hemodialysis. Factors that contribute to sleep disturbance and the use of hypnotic medications in hemodialysis patients were investigated. METHODS: With the use of a questionnaire-based survey, we examined the prevalence of symptoms that reflect sleep disorders such as insomnia, restless legs syndrome (RLS), and snoring and use of hypnotic medications in 252 hemodialysis patients. RESULTS: The overall prevalence of insomnia was 59.1%, with the prevalence of difficulty in initiating sleep (DIS), difficulty in maintaining sleep (DMS), and early morning awakening (EMA) being 47.6, 24.2, and 28.2%, respectively. Daytime sleepiness and habitual snoring were reported by 42.5 and 33.7%, respectively. The prevalence of routine use of hypnotic drugs was 25.8%. Both RLS and age were significantly associated with insomnia [odds ratio (OR), 3.75; p 0.001, OR, 1.03; p < 0.01]. RLS was a significant factor for DIS, DMS, and EMA (OR, 2.26; p < 0.05, OR, 3.44; p < 0.0005, OR, 4.25; p < 0.0005) and age was a significant factor for DMS and EMA (OR, 1.03; p = 0.053, OR, 1.05; p < 0.005). Both insomnia and snoring were associated with the use of hypnotic drugs (OR, 2.97; p < 0.001, 1.59; p=0.13). CONCLUSION: Both RLS and sleep-disordered breathing may contribute to sleep disturbance in hemodialysis patients. RLS in particular may be an important factor in insomnia, which in turn is likely responsible for the high prevalence of hypnotic drug use in hemodialysis patients.

Adult↗
PubMed2006

Suppression of AGE precursor formation following unilateral ureteral obstruction in mouse kidneys by transgenic expression of alpha-dicarbonyl/L-xylulose reductase.

Unilateral ureteral obstruction (UUO) of kidneys causes acute generation of carbonyl stress. By electrospray ionization/liquid chromatography/mass spectrometry (ESI/LC/MS) we measured the content of methyl glyoxal, glyoxal, and 3-deoxyglucosone in mouse kidney extracts following UUO. UUO resulted in elevation of these dicarbonyls in the obstructed kidneys. Furthermore, the accumulation of 3-deoxyglucosone was significantly reduced in the kidneys of mice transgenic for alpha-dicarbonyl/L-xylulose reductase (DCXR) as compared to their wild-type littermates, demonstrating 4.91+/-2.04 vs. 6.45+/-1.85 ng/mg protein (P=0.044) for the obstructed kidneys, and 3.68+/-1.95 vs. 5.20+/-1.39 ng/mg protein (P=0.026) for the contralateral kidneys. On the other hand, collagen III content in kidneys showed no difference as monitored by in situ hybridization. Collectively, DCXR may function in the removal of renal alpha-dicarbonyl compounds under oxidative circumstances, but it was not sufficient to suppress acute renal fibrosis during 7 d of UUO by itself.

Animals↗
PubMed2006

Neural circuits containing pallidotegmental GABAergic neurons are involved in the prepulse inhibition of the startle reflex in mice.

BACKGROUND: Prepulse inhibition (PPI) of the startle response is a measure of the inhibitory function and time-linked information processing by which a weak sensory stimulus (the prepulse) inhibits the startle response caused by a sudden intense stimulus. We attempted to clarify the neuronal circuits underlying the control of PPI of the startle reflex in mice. METHODS: c-Fos immunohistochemistry was used to detect neurons activated by startle pulse and/or prepulse trials. Behavioural pharmacology and tracing studies were also conducted. RESULTS: The lateral globus pallidus (LGP) was activated by prepulses. Activation of the caudal pontine reticular nucleus (PnC) evoked by the startle pulses was inhibited under PPI conditions. Double-immunostaining revealed that c-Fos-positive cells in the LGP following prepulse trials were GABAergic neurons. Bilateral microinjections of lidocaine into the LGP resulted in an impairment of PPI. Fluoro-gold infusion into the PnC and the pedunculopontine tegmental nucleus (PPTg) retrogradely labeled neurons in the PPTg and LGP, respectively. Microinjections of phaclofen into the PPTg significantly impaired PPI. CONCLUSIONS: These results suggest that GABAergic neurons in the LGP which project to the PPTg play a crucial role through the activation of GABAB receptors in the regulation of PPI of the startle reflex in mice.

Acoustic Stimulation↗
PubMed2006

Structure-based design of novel HIV-1 protease inhibitors to combat drug resistance.

Structure-based design and synthesis of novel HIV protease inhibitors are described. The inhibitors are designed specifically to interact with the backbone of HIV protease active site to combat drug resistance. Inhibitor 3 has exhibited exceedingly potent enzyme inhibitory and antiviral potency. Furthermore, this inhibitor maintains impressive potency against a wide spectrum of HIV including a variety of multi-PI-resistant clinical strains. The inhibitors incorporated a stereochemically defined 5-hexahydrocyclopenta[b]furanyl urethane as the P2-ligand into the (R)-(hydroxyethylamino)sulfonamide isostere. Optically active (3aS,5R,6aR)-5-hydroxy-hexahydrocyclopenta[b]furan was prepared by an enzymatic asymmetrization of meso-diacetate with acetyl cholinesterase, radical cyclization, and Lewis acid-catalyzed anomeric reduction as the key steps. A protein-ligand X-ray crystal structure of inhibitor 3-bound HIV-1 protease (1.35 A resolution) revealed extensive interactions in the HIV protease active site including strong hydrogen bonding interactions with the backbone. This design strategy may lead to novel inhibitors that can combat drug resistance.

Bridged Bicyclo Compounds, Heterocyclic↗
PubMed2006

Design, synthesis, and biological evaluation of the combinatorial library with a new spirodiketopiperazine scaffold. Discovery of novel potent and selective low-molecular-weight CCR5 antagonists.

We previously reported the discovery of several spirodiketopiperazine derivatives as potent CCR5 antagonists with anti-HIV activity. Herein, we describe in detail the identification of these lead compounds using a combinatorial chemistry approach. A novel spirodiketopiperazine scaffold was designed on the basis of the concept of the privileged structure of G-protein-coupled receptors (GPCRs). This new framework was obtained in acceptable yield with high purity from the readily prepared isonitrile resin through the Ugi reaction, sequential transformations, and cyclative cleavage. By measuring the inhibitory activity of each compound in the initial library against the intracellular calcium mobilization stimulated by MIP-1alpha, several compounds were found to show modest but selective CCR5 antagonistic activity. After the rapid evaluation of these hit compounds, several single-digit nanomolar, low-molecular-weight CCR5 antagonists that can potently block the infectivity and replication of laboratory and clinical strains of HIV as well as those of highly drug-resistant HIV variants with minimal cytotoxicity have been identified.

Animals↗
PubMed2006

Inhibition of HIV-1 replication by a peptide dimerization inhibitor of HIV-1 protease.

Peptides based on the amino (N) and carboxy (C)-terminal regions of human immunodeficiency virus type-1 (HIV-1) protease and on the C-terminus of p6* can inhibit HIV-1 protease activity by preventing dimerization. We developed a peptide dimerization inhibitor, P27, that included these domains and a cell permeable domain derived from HIV-1 Tat. P27 inhibited wild type (WT) and protease inhibitor (PI)-resistant HIV-1 protease (IC50: 0.23-0.32 microM). Kinetic and biochemical assays confirmed that P27 inhibits protease dimerization. Fluorescein-labeled peptide accumulated in MT-2 cells and protected acutely infected MT-2 cells from HIV-1-induced cytotoxicity (IC50: 5.1 microM). P27 also inhibited p24 accumulation from H9 and U937 cells chronically infected with WT or PI-resistant HIV-1. Immunoblot analysis on the supernatants and infected cells revealed a block in virus release by P27 rather than an inhibition of polyprotein processing. However, inhibition of p55 Gag processing by active-site inhibitors was enhanced when combined with P27, suggesting that P27 can affect protease function in maturing virions. Although P27 was rationally designed to block dimerization of the mature HIV-1 protease, the effects of P27 on HIV-1 replication may be related to partial inhibition of Gag-Pol processing leading to a disruption in virus release.

Cell Line↗
PubMed2006

Structural and molecular interactions of CCR5 inhibitors with CCR5.

We have characterized the structural and molecular interactions of CC-chemokine receptor 5 (CCR5) with three CCR5 inhibitors active against R5 human immunodeficiency virus type 1 (HIV-1) including the potent in vitro and in vivo CCR5 inhibitor aplaviroc (AVC). The data obtained with saturation binding assays and structural analyses delineated the key interactions responsible for the binding of CCR5 inhibitors with CCR5 and illustrated that their binding site is located in a predominantly lipophilic pocket in the interface of extracellular loops and within the upper transmembrane (TM) domain of CCR5. Mutations in the CCR5 binding sites of AVC decreased gp120 binding to CCR5 and the susceptibility to HIV-1 infection, although mutations in TM4 and TM5 that also decreased gp120 binding and HIV-1 infectivity had less effects on the binding of CC-chemokines, suggesting that CCR5 inhibition targeting appropriate regions might render the inhibition highly HIV-1-specific while preserving the CC chemokine-CCR5 interactions. The present data delineating residue by residue interactions of CCR5 with CCR5 inhibitors should not only help design more potent and more HIV-1-specific CCR5 inhibitors, but also give new insights into the dynamics of CC-chemokine-CCR5 interactions and the mechanisms of CCR5 involvement in the process of cellular entry of HIV-1.

Animals↗
PubMed2006

Structural basis for target protein recognition by the protein disulfide reductase thioredoxin.

Thioredoxin is ubiquitous and regulates various target proteins through disulfide bond reduction. We report the structure of thioredoxin (HvTrxh2 from barley) in a reaction intermediate complex with a protein substrate, barley alpha-amylase/subtilisin inhibitor (BASI). The crystal structure of this mixed disulfide shows a conserved hydrophobic motif in thioredoxin interacting with a sequence of residues from BASI through van der Waals contacts and backbone-backbone hydrogen bonds. The observed structural complementarity suggests that the recognition of features around protein disulfides plays a major role in the specificity and protein disulfide reductase activity of thioredoxin. This novel insight into the function of thioredoxin constitutes a basis for comprehensive understanding of its biological role. Moreover, comparison with structurally related proteins shows that thioredoxin shares a mechanism with glutaredoxin and glutathione transferase for correctly positioning substrate cysteine residues at the catalytic groups but possesses a unique structural element that allows recognition of protein disulfides.

Amino Acid Motifs↗
PubMed2005

Practical synthesis of a neuropeptide Y antagonist via stereoselective addition to a ketene.

[Reaction: see text]. The synthesis of neuropeptide Y antagonist 1, currently under clinical investigation for the treatment of obesity, is described. The convergent synthesis from trans-spirolactone carboxylic acid intermediate 2a and aminopyrazole 3 is predicated on a stereoselective route to the former. The coupling reaction of ethyl 4-oxocyclohexanecarboxylate (10a) with lithiated isonicotinamide 11 was investigated in detail, but even optimized conditions only provided a 45:55 ratio of trans:cis isomers (12a:12b). While selective crystallization schemes were developed to isolate the thermodynamically less stable trans isomer 2a, improved stereocontrol was subsequentially achieved by the application of ketene chemistry. The ketene formation and quench was investigated under a variety of conditions aimed at maximizing the trans:cis ratio. Reacting a mixture of carboxylic acids 2a and 2b with POCl3 in THF, followed by concomitant addition of tert-butyl alcohol in the presence of TMEDA at 35 degrees C provided a 4:1 ratio of trans:cis tert-butyl esters (18a:18b) via in situ ketene formation. Ester hydrolysis, followed by selective crystallization of undesired 2b as the HCl salt, led to isolation of 2a in 47% overall yield. Aminopyrazole intermediate 3 was synthesized via the condensation reaction of 2-fluorophenylhydrazine hydrochloride (4a) with acrylonitrile derivative 5 in 65-70% yield. Coupling of advanced intermediates 2a and 3b via activation with thionyl chloride gave a 92% yield of 1.

Bromides↗
PubMed2005

Repeated methamphetamine treatment impairs recognition memory through a failure of novelty-induced ERK1/2 activation in the prefrontal cortex of mice.

BACKGROUND: Recent clinical studies have suggested that chronic use of methamphetamine (METH) induces long-term cognitive deficits. To clarify the mechanism of METH-induced cognitive impairment, we investigated the effect of METH on cognitive function in mice. METHODS: Mice were repeatedly administered METH for 7 days, and their cognitive function was assessed using a novel-object recognition task. Therapeutic effects of clozapine and haloperidol on METH-induced cognitive impairment were investigated. Western blotting and specific inhibitors were employed to determine the role of extracellular signal-regulated kinase 1/2 (ERK1/2). RESULTS: Repeated METH treatment induced an impairment of recognition of novel objects and behavioral sensitization. These effects persisted for at least 28 days after the drug withdrawal. Clozapine, but not haloperidol, reduced METH-induced cognitive impairment. Hyperphosphorylation of ERK1/2 was found in the prefrontal cortex of mice exposed to the novel objects, but was abolished in mice treated with METH. Inhibition of ERK1/2 by the microinjection of PD98059 into the prefrontal cortex resulted in cognitive impairment. CONCLUSIONS: These results suggest that repeated METH treatment induces cognitive impairment, which is associated with the dysfunction of the ERK1/2 pathway in the prefrontal cortex.

Animals↗
PubMed2005

Identification of thioredoxin h-reducible disulphides in proteomes by differential labelling of cysteines: insight into recognition and regulation of proteins in barley seeds by thioredoxin h.

Using thiol-specific fluorescence labelling, over 30 putative target proteins of thioredoxin h with diverse structures and functions have been identified in seeds of barley and other plants. To gain insight at the structural level into the specificity of target protein reduction by thioredoxin h, thioredoxin h-reducible disulphide bonds in individual target proteins are identified using a novel strategy based on differential alkylation of cysteine thiol groups by iodoacetamide and 4-vinylpyridine. This method enables the accessible cysteine side chains in the thiol form (carbamidomethylated) to be distinguished from those inaccessible or disulphide bound form (pyridylethylated) according to the mass difference in the peptide mass maps obtained by matrix-assistend laser desorption/ionisation-time of flight mass spectrometry. Using this approach, in vitro reduction of disulphides in recombinant barley alpha-amylase/subtilisin inhibitor (BASI) by barley thioredoxin h isoform 1 was analysed. Furthermore, the method was coupled with two-dimensional electrophoresis for convenient thioredoxin h-reducible disulphide identification in barley seed extracts without the need for protein purification or production of recombinant proteins. Mass shifts of 15 peptides, induced by treatment with thioredoxin h and differential alkylation, identified specific reduction of nine disulphides in BASI, four alpha-amylase/trypsin inhibitors and a protein of unknown function. Two specific disulphides, located structurally close to the alpha-amylase binding surfaces of BASI and alpha-amylase inhibitor BMAI-1 were demonstrated to be reduced to a particularly high extent. For the first time, specificity of thioredoxin h for particular disulphide bonds is demonstrated, providing a basis to study structural aspects of the recognition mechanism and regulation of target proteins.

Allergens↗
PubMed2005

Role of sevelamer hydrochloride in the coronary artery calcification score.

The coronary artery calcification score (CACS) is higher in hemodialysis (HD) patients than in non-HD patients for each age group from the fifth to the eighth decade of life. In order to clarify the relationship between the rate of change in the CACS and several factors related to calcium (Ca) and phosphate (P) metabolism in HD patients, we determined the CACS twice in 144 HD outpatients at an interval of approximately 12 months (2003 and 2004). The dosage of vitamin D formulations (alfacalcidol or maxacalcitol) was reduced or ceased if the serum Ca concentration exceeded 5.0 mEq/L, or the serum P concentration exceeded 6.0 mg/dL, and the dosage of combined sevelamer hydrochloride (SH) and calcium carbonate (CaCO3), as the phosphate binder, was adjusted to maintain the concentrations below these levels. The study parameters were: (1) the total dosage of alfacalcidol (microg), maxacalcitol (microg), SH (mg), and CaCO3 at the time of each CACS measurement; and (2) serum concentrations of Ca, P, alkaline phosphatase, high-sensitivity parathyroid hormone (HS-PTH), total protein, albumin, total cholesterol, triglycerides (TG). Regression analysis showed a significant correlation among the total SH dosage, TG, and alphaCACS. Future investigations will include the differences in alphaCACS between patients treated with SH who experience a rise in Ca and/or P and those with a decrease in Ca and/or P.

Calcinosis↗
PubMed2005

Potent anti-R5 human immunodeficiency virus type 1 effects of a CCR5 antagonist, AK602/ONO4128/GW873140, in a novel human peripheral blood mononuclear cell nonobese diabetic-SCID, interleukin-2 receptor gamma-chain-knocked-out AIDS mouse model.

We established human peripheral blood mononuclear cell (PBMC)-transplanted R5 human immunodeficiency virus type 1 isolate JR-FL (HIV-1(JR-FL))-infected, nonobese diabetic-SCID, interleukin 2 receptor gamma-chain-knocked-out (NOG) mice, in which massive and systemic HIV-1 infection occurred. The susceptibility of the implanted PBMC to the infectivity and cytopathic effect of R5 HIV-1 appeared to stem from hyperactivation of the PBMC, which rapidly proliferated and expressed high levels of CCR5. When a novel spirodiketopiperazine-containing CCR5 inhibitor, AK602/ONO4128/GW873140 (molecular weight, 614), was administered to the NOG mice 1 day after R5 HIV-1 inoculation, the replication and cytopathic effects of R5 HIV-1 were significantly suppressed. In saline-treated mice (n = 7), the mean human CD4(+)/CD8(+) cell ratio was 0.1 on day 16 after inoculation, while levels in mice (n = 8) administered AK602 had a mean value of 0.92, comparable to levels in uninfected mice (n = 7). The mean number of HIV-RNA copies in plasma in saline-treated mice were approximately 10(6)/ml on day 16, while levels in AK602-treated mice were 1.27 x 10(3)/ml (P = 0.001). AK602 also significantly suppressed the number of proviral DNA copies and serum p24 levels (P = 0.001). These data suggest that the present NOG mouse system should serve as a small-animal AIDS model and warrant that AK602 be further developed as a potential therapeutic for HIV-1 infection.

Animals↗