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Biomedical subjects

Jun Haginaka

Publications and source records attributed to Jun Haginaka.

At least 19 recordsLinked to original sources
PubMed2006

Uniformly-sized, molecularly imprinted polymers for (-)-epigallocatechin gallate, -epicatechin gallate and -gallocatechin gallate by multi-step swelling and polymerization method.

Uniformly-sized, molecularly imprinted polymers (MIPs) for (-)-epigallocatechin gallate (EGCg), -epicatechin gallate (ECg) and -gallocatechin gallate (GCg) were prepared by a multi-step swelling and polymerization method using 2-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as a cross-linker and cyclohexanol as a porogen. Molecular recognition abilities of the obtained MIPs were evaluated in liquid chromatography using a mixture of ethanol and water, or ethanol as the eluent. Each MIP gave the highest molecular recognition ability for the respective template molecule. In addition, (-)-EGCg and -ECg had the same configuration (2R,3R) at positions 2 and 3, and therefore resulting in high cross reactivity each other. However, (-)-GCg, which has different configuration at position 2 with (-)-EGCg and -ECg, showed low cross reactivity with them. On the other hand, those MIPs showed no molecular recognition against (-)-epigallocatechin and -epicatechin, which have no gallate group at position 3. These results indicate that the MIPs prepared can recognize configuration at position 2 and a gallate group at position 3. Furthermore, the MIP for (-)-GCg could be successfully used for isolating (-)-EGCg and -ECg from green tea extract.

Catechin↗
PubMed2006

Molecularly imprinted polymers for triazine herbicides prepared by multi-step swelling and polymerization method. Their application to the determination of methylthiotriazine herbicides in river water.

Uniformly-sized, molecularly imprinted polymers (MIPs) for atrazine, ametryn and irgarol were prepared by a multi-step swelling and polymerization method using ethylene glycol dimethacrylate as a cross-linker and methacrylic acid (MAA), 2-(trifluoromethyl) acrylic acid (TFMAA) or 4-vinylpyridine either as a functional monomer or not. The MIP for atrazine prepared using MAA showed good molecular recognition abilities for chlorotriazine herbicides, while the MIPs for ametryn and irgarol prepared using TFMAA showed excellent molecular recognition abilities for methylthiotriazine herbicides. A restricted access media-molecularly imprinted polymer (RAM-MIP) for irgarol was prepared followed by in situ hydrophilic surface modification using glycerol dimethacrylate and glycerol monomethacrylate as hydrophilic monomers. The RAM-MIP was applied to selective pretreatment and enrichment of methylthiotriazine herbicides, simetryn, ametryn and prometryn, in river water, followed by their separation and UV detection via column-switching HPLC. The calibration graphs of these compounds showed good linearity in the range of 50-500 pg/mL (r > 0.999) with a 100 mL loading of a river water sample. The quantitation limits of simetryn, ametryn and prometryn were 50 pg/mL, and the detection limits were 25 pg/mL. The recoveries of simetryn, ametryn and prometryn at 50 pg/mL were 101%, 95.6% and 95.1%, respectively. This method was successfully applied for the simultaneous determination of simetryn, ametryn and prometryn in river water.

Herbicides↗
PubMed2006

Simultaneous determination of bisphenol A and its halogenated derivatives in river water by combination of isotope imprinting and liquid chromatography-mass spectrometry.

A restricted access media-molecularly imprinted polymer (RAM-MIP) for [2H16]bisphenol A (BPA-d16) was prepared by a multi-step swelling and polymerization method using 4-vinylpyridine as a functional monomer and ethylene glycol dimethacrylate as a cross-linker, followed by hydrophilic surface modification using glycerol dimethacrylate and glycerol monomethacrylate as hydrophilic monomers. The obtained RAM-MIP showed excellent molecular recognition abilities for BPA and BPA-d6 as well as BPA-d16 used as the template molecule, and good ones for tetrachlorobisphenol A (Cl4-BPA) and tetrabromobisphenol A (Br4-BPA). Next, the RAM-MIP was utilized for selective on-line pretreatment and enrichment of BPA, Cl4-BPA and Br4-BPA in a river water sample, followed by their separation and determination by LC-MS. The calibration graphs of BPA, Cl4-BPA and Br4-BPA, constructed using BPA-d6 as an internal standard, showed good linearity in the range of 12.5-200 pg/mL (r > 0.999) with a 2-mL injection of a river water sample. The inter-day precision data for the assay of BPA, Cl4-BPA and Br4-BPA at 25 pg/mL were 1.08, 3.67 and 1.58%, respectively. Furthermore, this method was successfully applied for the simultaneous determination of BPA and its halogenated derivatives in river water.

Benzhydryl Compounds↗
PubMed2006

Uniformly-sized, molecularly imprinted polymers for nicotine by precipitation polymerization.

Uniformly-sized, molecularly imprinted polymers (MIPs) for (S)-nicotine have been prepared by a precipitation polymerization method using methacrylic acid (MAA) or 2-(trifluoromethyl)acrylic acid (TFMAA) as a functional monomer and divinylbenzene (DVB) as a cross-linker in a mixture of toluene and acetonitrile. The (S)-nicotine-imprinted MAA-co-DVB polymers were monodispersed microspheres of about 4 microm in diameter, while the TFMAA-co-DVB ones were gel-like. Molecular recognition abilities of the former MIPs were evaluated for nicotine and its structurally related compounds in liquid chromatography using a mixture of sodium phosphate buffer and acetonitrile as the eluent. Enantioseparation of nicotine was attained using the (S)-nicotine-imprinted MAA-co-DVB polymers. Furthermore, they could selectively trap nicotine in cigarette smoke extracts.

Chemical Precipitation↗
PubMed2006

Corosolic acid prevents oxidative stress, inflammation and hypertension in SHR/NDmcr-cp rats, a model of metabolic syndrome.

Corosolic acid (CRA), a constituent of banaba leaves, has been reported to have anti-inflammatory and hypoglycemic activities. The aim of this study was to determine the effects of CRA on metabolic risk factors including obesity, hypertension, hyperinsulinemia, hyperglycemia, and hyperlipidemia together with oxidative stress and inflammation, all of which are characteristic of the SHR/NDmcr-cp (cp/cp) (SHR-cp) rat, an animal model of metabolic syndrome. Six-week-old male SHR-cp rats were fed a high fat diet containing 0.072% CRA for 14 weeks. Treatment with CRA lowered blood pressure, which was elevated in control animals, by 10% after 8 weeks, and serum free fatty acids by 21% after 2 weeks. CRA treatment resulted in decreases in the levels of the oxidative stress markers thiobarbituric acid-reactive substances and 8-hydroxydeoxyguanosine by 27% and 59%, respectively, after 2 weeks. CRA treatment also reduced the levels of myeloperoxidase markers, 3-nitrotyrosine and 3-chlorotyrosine by 38% and 39%, respectively, after 10 weeks, and tended to decrease the levels of high sensitivity C-reactive protein, a marker of inflammation, after 6 weeks. However, CRA had no effect on weight gain or hyperglycemia. These results demonstrate that CRA can ameliorate hypertension, abnormal lipid metabolism, and oxidative stress as well as the inflammatory state in SHR-cp rats. This implies that CRA can be beneficial for preventing atherosclerosis-related diseases that are an increasing health care problem worldwide.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Multiple ligand-binding properties of the lipocalin member chicken alpha1-acid glycoprotein studied by circular dichroism and electronic absorption spectroscopy: the essential role of the conserved tryptophan residue.

Multiple ligand-binding properties of the 30-kDa chicken alpha(1)-acid glycoprotein (cAGP), a member of the lipocalin protein family, were investigated for the first time by using circular dichroism (CD) and UV/Vis absorption spectroscopy methods. By measuring induced CD (ICD) spectra, high-affinity binding (K(a) approximately 10(5)-10(6) M(-1)) of several drugs, dyes and natural compounds to cAGP was demonstrated including antimalarial agents (quinacrine, primaquine), phenotiazines (chlorpromazine, methylene blue), propranolol, non-steroidal antiinflammatory drugs (ketoprofen, diclofenac), tamoxifen, diazepam, tacrine, dicoumarol, cationic dyes (auramine O, thioflavine T, ethidium bromide), benzo[a]pyrene, L-thyroxine, bile pigments (bilirubin, biliverdin), alkaloids (piperine, aristolochic acid), saturated and unsaturated fatty acids. Analysis of the extrinsic CD spectra with the study of the covalently modified protein and CD displacement experiments revealed that a single Trp26 residue of cAGP conserved in the whole lipocalin family is part of the binding site, and it is essentially involved in the ligand-binding process via pi-pi stacking interaction resulting in the appearance of strong induced CD bands due to the non-degenerate intermolecular exciton coupling between the pi-pi* transitions of the stacked indole ring-ligand chromophore. The finding that cAGP is able to accommodate a broad spectrum of ligands belonging to different chemical classes suggests that its core beta-barrel cavity is unusually wide containing overlapping sub-sites. Significance of these new data in understanding of the ligand-binding properties of other lipocalins, especially that of human AGP, and potential practical applications are briefly discussed. Overall, cAGP serves as a simple, ultimate model to extend our knowledge on ligand-binding properties of lipocalins and to study the role of tryptophan residues in molecular recognition processes.

Animals↗
PubMed2006

Elevated circulating levels of markers of oxidative-nitrative stress and inflammation in a genetic rat model of metabolic syndrome.

Metabolic syndrome is a cluster of metabolic diseases that in essence greatly promotes progression of atherosclerosis. We used a genetic model of the metabolic syndrome, the SHR/NDmcr-cp (SHR/cp) rat, from 6 to 40 weeks of age to investigate whether systemic oxidative stress, a major cause of atherosclerosis, increases in this syndrome. Nine-week-old male rats already showed manifestations of metabolic syndrome, including heavier body weight, higher blood pressure and higher levels of serum glucose, insulin and various lipids compared to the age-matched Wistar Kyoto (WKY) rats used as a genetic control. These metabolic parameters gradually progressed with age. Likewise, the serum levels of oxidative stress markers, including lipid peroxides, which oxidatively modify low-density lipoprotein (LDL) and 8-hydroxydeoxyguanosine (8-OHdG), gradually increased in SHR/cp rats. The serum levels of 3-nitrotyrosine and 3-chlorotyrosine also persistently increased, indicating the involvement of peroxynitrite or myeloperoxidase-catalyzed oxidation. In addition, high-sensitivity C-reactive protein (hsCRP), an early marker of inflammation, temporarily increased in SHR/cp rats compared to WKY rats. These findings suggest that oxidative stress, as well as nitrative stress and inflammation, increases in the metabolic syndrome, which may contribute to the development of atherosclerosis.

Animals↗
PubMed2006

Preparation and evaluation of a novel chiral stationary phase based on covalently bonded chitosan for ligand-exchange chromatography.

A novel chiral stationary phase based on chitosan covalently bonded onto silica gels has been prepared and used for the separation of various alpha-amino acid enantiomers as well as alpha-hydroxycarboxylic acid enantiomers by chiral ligand-exchange chromatography with copper(II) as a complexing ion. The methanol content and copper(II) ion concentration in the eluent affected retentivity and enantioselectivity. Furthermore, a plausible chiral recognition mechanism for resolution of alpha-amino acids was proposed.

5-Hydroxytryptophan↗
PubMed2006

HPLC retention behaviors of poly-aromatic-hydrocarbones on Cu(II)-octabromotetrakis(4-carboxyphenyl)porphine derivatives-immobilized aminopropyl silica gels in polar and non-polar eluents.

As one of approaches of developing novel HPLC stationary phases, we prepared Cu-octabromotetrakis(4-carboxyphenyl)porphine derivative-immobilized silica gels (Cu-OBTCPP(D)), and evaluated the availability of the resultant Cu-OBTCPP(D) as a stationary phase for separation of poly-aromatic-hydrocarbons (PAHs) and their related compounds. A Cu-OBTCPP(D) column was revealed to have an ability to separate simple PAHs and be useful as a stationary phase in both polar and non-polar eluents. The retention property of the Cu-OBTCPP(D) column was evaluated in various comparative experiments using commercially available columns. In comparison with 2-(1-pyrenyl)ethyl dimetylsilyl silica gel column (PYE column) regarding the retention behavior for PAHs etc., the Cu-OBTCPP(D) column showed stronger interactions involving pi electron in non-polar eluent than PYE column. In comparison with a pentabromobenzyloxy propylsilyl silica gel column (PBB column) regarding the influence of bromination, the Cu-OBTCPP(D) column was affected differently from the PBB column. In comparison with nitrophenylethyl silica gel column (NPE column) regarding the retention behavior for compounds having a dipole in a non-polar eluent, the Cu-OBTCPP(D) column showed electrostatic interactions such as dipole-dipole interaction equivalent to or larger than the NPE column.

Chemical Phenomena↗
PubMed2006

HPLC retention behaviors of pi-electron rich compounds on Ni2+- and Cu2+-phthalocyanine derivatives bound to silica gels in polar eluents.

The effect of the central metal of columns packed with silica gels binding Ni(2+)- and Cu(2+)-phthalocyanine derivatives (Ni-and Cu-PCS(D)s) on the retention behavior of poly-aromatic-hydrocarbons (PAHs) thereof in a polar eluent was examined. The retention factors of PAHs on the Ni- and Cu-PCS(D)s in 80% methanol showed a good linear correlation. The Cu-PCS(D) column exhibited the pi-pi interactions for PAHs, while the Ni-PCS(D) column exhibited the pi-d interactions for PAHs in addition to the pi-pi interaction for PAHs. Further, an investigation of the retention behavior of anthracene derivatives having different substituents revealed that the Ni- and Cu-PCS(D) columns could recognize the differences of substituents only in a polar eluent.

Chromatography, High Pressure Liquid↗
PubMed2005

Investigation of chiral recognition mechanism on chicken alpha(1)-acid glycoprotein using separation system.

Chicken alpha1-acid glycoprotein (alpha1-AGP) consists of 183 amino acid residues and has only one Trp residue at the 26 position. In this study, the Trp26 residue was modified with 2-nitrophenylsulfenyl chloride and chiral separation of neutral, acidic and basic compounds was examined on chicken alpha1-AGP and Trp-modified chicken alpha1-AGP columns. Chiral separation of propranolol, alprenolol and oxprenolol was lost on the Trp-modified chicken alpha1-AGP column, while chlorpheniramine, ketoprofen and benzoin were still enantioseparated on the Trp-modified chicken alpha1-AGP column despite of lower enantioselectivity than that on the chicken alpha1-AGP column. These results suggest that the Trp26 residue could be responsible for chiral recognition of these compounds. Competition studies using N,N-dimethyl-n-octylamine (DMOA) as a competitor indicated that propranolol, alprenolol and oxprenolol competed with DMOA on a single binding site near the Trp26 region and that further bindings of chlorpheniramine, ketoprofen and benzoin occurred at the secondary binding site in a non-competitive fashion with DMOA.

Animals↗
PubMed2005

Enantiomeric purity determination of acetyl-L-carnitine by NMR with chiral lanthanide shift reagents.

Enantiomer signal separation of acetyl-carnitine chloride was obtained on a 500 MHz Nuclear Magnetic Resonance (1H NMR) analysis by fast diastereomeric interaction with chiral shift reagents such as chiral lanthanide-camphorato or chiral samarium-pdta shift reagents. Effects of the kinds of chiral shift reagents and the molar ratio of chiral shift reagent to acetyl-carnitine chloride on enantiomer signal separation were investigated and evaluated. Optimization of the experimental conditions provided two significant split signals for the enantiomers, leading to the successful quantitative analysis. Distinguishment of 0.5% of the minor enantiomer (D-form) in acetyl-L-carnitine chloride was found to be possible by 1H NMR with tris[3-(heptafluoropropylhydroxymethylene)-D-camphorato] and praseodymium derivative, (Pr[hfc]3), as chiral shift reagents.

Acetylcarnitine↗
PubMed2005

Uniformly sized molecularly imprinted polymer for atropine and its application to the determination of atropine and scopolamine in pharmaceutical preparations containing Scopolia extract.

A uniformly sized molecularly imprinted polymer (MIP) for atropine has been prepared. The MIP was prepared using 2-(trifluoromethyl) acrylic acid and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively, by a multi-step swelling and thermal polymerization method. The selectivity factor, which is defined as the ratio of the retention factors (k) on the molecularly imprinted and non-imprinted polymers, k(imprinted)/k(non-imprinted), was 2.2 for atropine on the MIP. The obtained MIP was applied for the determination of tropane alkaloids (atropine and scopolamine) in a commercial gastrointestinal drug by a column-switching HPLC system, consisting of an MIP material as a pre-column, and a conventional cation-exchange analytical column. An interference peak was observed at the retention time of atropine derived from pre-column. However, since the peak area was less than 0.5% the peak area of atropine of a standard solution under the analytical conditions of this study (0.2 microg of atropine was loaded), this interference was negligible in the determination of atropine. On the other hand, no interference peak was observed at the retention time of scopolamine. Calibration curves of atropine and scopolamine showed good linearity in the range of 0.02-0.9 microg/ml (r=0.9999) and 0.003-0.09 microg/ml (r=0.9998), respectively. The mean recoveries of atropine and scopolamine from a placebo pharmaceutical preparation sample were 98.9 and 99.9%, respectively. The intra-day precision (measured by relative standard deviation, R.S.D. (%)) of both ingredients was less than 2.0%. The optimized column-switching system was applied successfully to the determination of atropine and scopolamine in a commercial gastrointestinal drug.

Acrylates↗
PubMed2005

Screening of bitterness-suppressing agents for quinine: the use of molecularly imprinted polymers.

The purpose of the present study was to examine the possibility of using molecularly imprinted polymers (MIPs) to screen for bitterness-suppressing agents. Quinine was selected as the bitter substance standard. L-arginine (L-Arg), L-ornithine (L-Orn), L-lysine (L-Lys), and L-citrulline (L-Ctr) were tested as bitterness suppressant candidates. In a high-performance liquid chromatography study using a uniformly sized MIP for cinchonidine, which has a very similar structure to quinine, the retention factor (k) of quinine was significantly shortened by the addition of L-Arg or L-Orn to the mobile phase, whereas slight or no decrease was observed when L-Ctr and L-Lys were added. The abilities of these amino acids to decrease the k of quinine were ranked in the following order: L-Arg = (L-Orn >(L-Ctr >>(L-Lys. A linear relationship between the reciprocal of k and the concentration of the amino acids indicated a single competitive model at a single site. The magnitude of the association constants obtained seemed to be directly related to the inhibitory effect of the test substances on the affinity of quinine for the receptor site. Nuclear magnetic resonance and molecular modeling studies suggested a one-to-two hydrogen-bonding-based complex formation of one quinine molecule with two methacrylic acid molecules (Q-2MAA) in chloroform. In the molecular modeling studies, the N--N distance of the quinine molecule in the assumed Q-2MAA complex was calculated to be 5.12 angstroms, similar to the N - N distances of the two amino acid complexes (L-Arg-2MAA, L-Orn-2MAA), which were 4.84 and 5.30 angstroms, respectively. This suggests that L-Arg and L-Orn may compete with the quinine molecule in the cinchonidine-imprinted space. Finally, the results of human gustatory sensation tests correlated well with the MIP data. The proposed method using MIPs seems to have a potential for screening bitterness-suppressing agents for quinine.

Arginine↗
PubMed2005

Retentivity and enantioselectivity of uniformly-sized molecularly imprinted polymers for (S)-nilvadipine in aqueous and non-aqueous mobile phases.

Uniformly-sized molecularly imprinted polymers (MIPs) for (S)-nilvadipine have been prepared by a multi-step swelling and polymerization method using methacrylic acid or 4-vinylpyridine (4-VPY) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, and toluene, chloroform, cyclohexanol or phenylacetonitrile as a porogen. The chiral recognition abilities of the MIPs for nilvadipine were evaluated using aqueous and non-aqueous mobile phases. Among the MIPs, the (S)-nilvadipine-imprinted 4-VPY-co-EDMA polymers prepared using toluene as a porogen showed the highest recognition ability for nilvadipine in both aqueous and non-aqueous mobile phases. In addition to molecular shape recognition, hydrogen-bonding interactions of the NH proton of nilvadipine with a pyridyl group of the (S)-nilvadipine-imprinted 4-VPY-co-EDMA polymers could play an important role in the retention and chiral recognition of nilvadipine in aqueous and non-aqueous mobile phases. Furthermore, the MIP for (S)-nilvadipine gave the highest molecular recognition ability when a porogenic solvent during polymerization was used as the mobile phase modifier.

Chromatography, High Pressure Liquid↗
PubMed2004

Identification of disulfide bonds and site-specific glycosylation in chicken alpha1-acid glycoprotein by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Recently, we reported the amino acid sequence of chicken alpha1-acid glycoprotein (chicken alpha1-AGP) [Biochem. Biophys. Res. Commun. 295 (2002) 587]. In this study, we located the disulfide bonds and site-specific glycosylation in chicken alpha1-AGP using tryptic digests of carbamidomethylated chicken alpha1-AGP, carbamidomethylated completely deglycosylated chicken alpha1-AGP (cd-alpha1-AGP), and nonreduced denatured cd-alpha1-AGP by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Based on the detection of peptides mlz 3037.4 (amino acid sequences 69-76 plus 161-183) and 3453.3 (amino acid sequences 69-80 plus 161-183), the two disulfide bonds of chicken alpha1-AGP were determined to be located at Cys 6-Cys 146 and Cys 73-Cys 163. The results also showed that Asn 16, 70, 77, and 87 were fully glycosylated and that Asn 62 was partially glycosylated.

Amino Acid Sequence↗
PubMed2004

Retentivity and enantioselectivity of uniformly sized molecularly imprinted polymers for d-chlorpheniramine and -brompheniramine in hydro-organic mobile phases.

Uniformly sized molecularly imprinted polymers (MIPs) for d-chlorpheniramine (CP) and -brompheniramine (BP) have been prepared by a multi-step swelling and polymerization method using methacrylic acid (MAA) or 2-(trifluoromethyl)acrylic acid (TFMAA) and ethylene glycol dimethacrylate (EDMA) as a functional monomer and cross-linker, respectively. The retentive and enantioselective properties of CP, BP and their structurally related compounds on the MIPs were evaluated using hydro-organic mobile phases. CP and BP enantiomers were retained the most as a monovalent cation on MAA-co-EDMA polymers and a divalent cation on TFMAA-co-EDMA polymers. Ion exchange and hydrophobic interactions could mainly work for the retention and enantioseparation of CP and BP on both MAA-co-EDMA and TFMAA-co-EDMA polymers in hydro-organic mobile phases. Though the respective MIPs gave the highest enantioselectivity for the template molecule, cross-reactivity for CP and BP was observed with them.

Brompheniramine↗