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Takako Nakamura

Publications and source records attributed to Takako Nakamura.

17 recordsLinked to original sources
PubMed2006

Geometric properties of covalently bonded DNA on single-crystalline diamond.

Diamond is a promising candidate for bioapplications. Properties of hybridized DNA arrays on single-crystalline diamond are studied on a microscopic level by atomic force microscopy (AFM) in buffer solutions. Compact DNA layers in a thickness of 76 A are resolved by optimizing phase and height contrast in AFM. The height shows some long-range (30 nm) undulations of +/-5 A due to tip and DNA interactions. The axis of double helix DNA is oriented at about 36 degrees with respect to the diamond surface. DNA molecules can be removed by contact-mode AFM with forces >45 nN, indicating stronger DNA bonding than on gold substrates.

DNA↗
PubMed2006

Simultaneous determination of three local anesthetic drugs from the pipecoloxylidide group in human serum by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous analysis of the local anesthetic amide drugs, bupivacaine, mepivacaine and ropivacaine, belonging to the pipecoloxylidide group using a C(18) reversed-phase column (150 x 4.6 mm I.D.) filled with 5-microm particles and attached to a UV detector. The mobile phase was composed of acetonitrile-methanol-30 mM NaH(2)PO(4) (pH 5.6) (100:100:300, v/v/v) and the flow rate was 1ml/min. The absorbance of the eluate was monitored at 210 nm. The retention times of the three compounds were: 4.6 min (mepivacaine), 9.7min (ropivacaine) and 16.4 min (bupivacaine). With this sample preparation method, good and consistent recoveries of the three compounds were obtained: 88-91% for mepivacaine, 87-89% for ropivacaine and 88-91% for bupivacaine. The limit of quantification for three compounds in human serum was 2 ng/ml for mepivacaine, 5 ng/ml for bupivacaine and ropivacaine. This method may be useful in clinical and forensic applications for the determination or identification of the local anesthetic drugs: bupivacaine, mepivacaine or ropivacaine.

Amides↗
PubMed2006

Effect of propofol on ropivacaine metabolism in human liver microsomes.

A combination of the general anesthetic propofol and epidural anesthesia with a local anesthetic is widely used. The metabolism of ropivacaine and that of lidocaine are mediated by similar P450 isoforms. Previously, propofol was found to inhibit the metabolism of lidocaine in vitro. Here we investigated whether propofol inhibits the metabolism of ropivacaine using human liver microsomes in vitro. Ropivacaine (6.0 micromol.l(-1)) as the substrate and propofol (1-100 micromol.l(-1)) were reacted together using human microsomes. The concentrations of ropivacaine and its major metabolite 2',6'-pipecoloxylidide (PPX) were measured using high-performance liquid chromatography. The metabolic activity of ropivacaine was reflected in the production of PPX. The inhibitory effects of propofol on ropivacaine metabolism were observed to be dose-dependent. The IC50 of propofol was 34.9 micromol.l(-1). Propofol shows a competitive inhibitory effect on the metabolism of ropivacaine (i.e., PPX production mediated by CYP3A4) in human CYP systems in vitro.

Amides↗
PubMed2006

Effects of premedication medicines on the formation of the CYP3A4-dependent metabolite of ropivacaine, 2', 6'-Pipecoloxylidide, on human liver microsomes in vitro.

Ropivacaine is a relatively new amide-type local anaesthetic, mainly used for surgery and postoperative pain relief. In this study we have investigated the interaction between the CYP3A4 metabolite of ropivacaine, 2',6'-pipecoloxylidide (PPX), and premedication with, i.e., psychotropic and antianxiety agents (diazepam, midazolam), hypnotics (thiamylal), local anaesthetics (lidocaine), depolarizing muscular relaxants (vecuronium), antihypertensive (clonidine) and H(2)-receptor antagonist (cimetidine) using human liver microsomes in vitro. The effects of the interaction between PPX and premedications were examined using a human liver microsomal preparation in vitro. The concentrations of ropivacaine and PPX were determined by HPLC with UV detection. The apparent Michaelis-Menten constant (Km) and the maximal velocity of total metabolic formation (V(max)) of PPX, the main metabolite of ropivacaine in human liver microsomes, were 17.7 (microM, mean) and 711 (nmol/min./mg protein, mean), respectively. Five premedications (diazepam, lidocaine, cimetidine, vecuronium and clonidine) did not inhibit ropivacaine metabolism in human liver microsomes at concentrations within the therapeutic range. However, midazolam and thiamylal weakly inhibited ropivacaine metabolism in competitive manner (IC(50) 7.8 microM and 250 microM, respectively). The results show lack of interaction between ropivacaine and seven premedication medicines within the therapeutic range of ropivacaine using human liver microsomes in vitro.

Amides↗
PubMed2005

A study of the in vitro interaction between ethanol, and triazolam and its two metabolites using human liver microsomes.

AIM: Triazolam is widely used as an ultrashort-acting anxiolytic drug and hypnosedatives and its effect appears at very low doses. Ethanol is used as a social drug worldwide. Sometimes, toxic interactions occur following combined administration of these two drugs. In this study, we have investigated the interaction between alcohol and triazolam in vitro. METHODS: The interaction effects between alcohol and triazolam were examined by a mixed-function oxidation reaction using a human liver microsomal preparation. Triazolam and its two metabolites (alpha-hydroxytriazolam: alpha-OH triazolam, 4-hydroxytriazolam: 4-OH triazolam) were measured by HPLC/UV. RESULTS: The production of alpha-OH triazolam and 4-OH triazolam was shown to be weakly inhibited by 13-29% (p < 0.05) and 8-14%,respectively, by ethanol (20-80 mM). CONCLUSIONS: These results using a human liver microsomal preparation show that the formation of both metabolites of triazolam is weakly inhibited by ethanol. Toxic levels may be reached by simultaneous administration of ethanol and triazolam.

Anti-Anxiety Agents↗
PubMed2005

CYP2C19 genotype affects diazepam pharmacokinetics and emergence from general anesthesia.

OBJECTIVES: Diazepam is widely used to relieve preoperative anxiety in patients. The objective of this study was to investigate the effects of polymorphism in CYP2C19 and the effects of CYP3A4 messenger ribonucleic acid (mRNA) content in blood on recovery from general anesthesia and on diazepam pharmacokinetics. METHODS: Sixty-three Japanese patients were classified into the following 3 genotype (phenotype) groups on the basis of polymerase chain reaction-restriction fragment length polymorphism analysis of CYP2C19 polymorphism: no variants, *1/*1 (extensive metabolizer [EM]); 1 variant, *1/*2 or *1/*3 (intermediate metabolizer [IM]); and 2 variants, *2/*2, *2/*3, or *3/*3 (poor metabolizer [PM]). We assessed the effects of these polymorphisms and of CYP3A4 mRNA content in the lymphocytes on the patients' recovery from general anesthesia. RESULTS: CYP2C19 genotyping analysis in the 63 subjects showed that 32%, 46%, and 22% of subjects were classified into the EM, IM, and PM groups, respectively. The PM subjects showed a larger area under the curve representing the concentration of diazepam over a 24-hour period (AUC(0-24)) (2088 +/- 378 ng/mL.h(-1), P = .0259), lower clearance of diazepam (0.049 +/- 0.009 L.h(-1).kg(-1), P = .0287), and longer emergence time (median, 18 minutes; 25th-75th percentile range, 13-21 minutes; P < .001) in comparison with subjects in the EM group (AUC(0-24), 1412 +/- 312 ng/mL; clearance, 0.074 +/- 0.018 L.h(-1).kg(-1); and emergence time, 10 minutes, 8-12 minutes [median and 25th-75th percentile range]). The IM group also showed a longer emergence time (median, 13 minutes; 25th-75th percentile range, 9-20 minutes; P < .001) and a larger variation in this parameter in comparison with the EM group. The distributions of the CYP2C19 genotype were significantly different between the 2 groups (rapid emergence <20 minutes, slow emergence >20 minutes) (P = .0148). The mean value of the CYP3A4 mRNA level in the slow-emergence group (mean +/- SD, 4.80 +/- 3.99 x10(-10)) was significantly lower than that of the rapid-emergence group (mean +/- SD, 12.50 +/- 11.90 x10(-10)) (P = .0315). However, there was no significant correlation between emergence time and CYP3A4 mRNA levels (r = 0.239, P = .0601). CONCLUSION: We found that the CYP2C19 genotype affects diazepam pharmacokinetics and emergence from general anesthesia and that the slow-emergence group possesses lower levels of CYP3A4 mRNA than are found in the rapid-emergence group.

Actins↗
PubMed2005

[Asystole during electroconvulsive therapy].

BACKGROUND: Asystole during electroconvulsive therapy (ECT) has been reported as an uncommon but fatal complication. But cardiac movement during electrical stimulation has not been well known. METHODS: The cardiac movements during electrical stimulation of fifty psychiatric patients treated by ECT under general anesthesia were observed utilizing thoracic echocardiography. Observations of 117 times were performed. Rate pressure products (RPP) immediately before stimulation and during 10 minutes after stimulation were calculated. Asystole was defined as absence of heartbeat for over 2 seconds. RESULTS: Asystoles were observed 57 times (48.7%). The heartbeat recovered immediately after stimulation in all asystole cases. RPP increased just after stimulation in all cases. Asystole cases had significantly greater variation of RPP than cases without aystole. (P = 0.0082). CONCLUSIONS: Electrical stimulation by ECT activates parasympathetic nervous system and convulsion by the stimulation activates sympathetic nervous system. As asystole case had good reactive automatic nervous system, asystole might have been provoked by the stimulation with a greater increase in RPP after the stimulation.

Anesthesia, General↗
PubMed2004

Photochemical modification of diamond films: introduction of perfluorooctyl functional groups on their surface.

Photolysis of perfluoroazooctane with diamond films led the chemical modification of the surface to introduce perfluorooctyl functional groups, confirmed by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and time-of-flight secondary ion mass spectrometry measurements. Diamond films modified with fluorine moieties showed improved frictional property and reduction of surface energy, as evaluated by contact angle to water, compared with a pristine diamond film. The contact angle and friction coefficient of chemically modified diamond film are 118 degrees and 0.1, respectively. The results of the value of the contact angle depending on irradiation times are consistent with those of the F/C ratio of fluorinated diamond films by monitoring with XPS.

Journal Article↗
PubMed2003

[The effects of indomethacin spray on the pain of stomatitis in the patients for hematopoietic stem cell transplantation].

We studied the effects of 0.25% indomethacin (IM) spray as an in-hospital preparation on the pain of stomatitis after hematopoietic stem cell transplantation in 9 patients with various types of leukemia by measuring the change in pain and the decrease in morphine dose. Stomatitis above grade 2 (painful erythema, edema, or ulcers but can eat or swallow) appeared in all patients as white blood cell (WBC) counts declined after transplantation, and clockwise hysteresis was observed between WBC counts and the grade of stomatitis. When the patients used IM spray for the pain of stomatitis and were judged the grade of pain using a face scale of five grades (0-4) before and after the use of this spray, the mean grades of pain at the maximal pain during the appearance of stomatitis declined from 3.4 to 1.8 (n = 5). Furthermore, the concurrent intravenous dose of morphine markedly decreased during IM spray use. There was no complaint concerning the taste and convenience of IM spray by patients. The risk of systemic adverse effects was considered relatively low based on the small amounts of IM applied to the mouth mucosa. In conclusion, it is suggested that IM spray is effective for the relief of stomatitis pain in patients who have undergone hematopoietic stem cell transplantation and is a useful preparation for immediate self-medication upon the appearance of stomatitis pain. We considered that the application of IM spray will contribute to the improvement of patient quality of life.

Administration, Buccal↗
PubMed1999

Radical Cyclization in Heterocycle Synthesis. 6.(1) A New Entry to Cyclic Amino Alcohols via Stannyl Radical Cyclization of Oxime Ethers Connected with Aldehydes or Ketones.

Oxime ethers connected by a tether to aldehydes or ketones efficiently cyclize via stannyl radical addition-cyclization to provide a new entry to cyclic amino alcohols. Upon treatment with tributyltin hydride in the presence of AIBN, oxime ethers connected with either an aldehyde or a ketone via a nitrogen atom smoothly underwent stannyl radical addition-cyclization to give five- to seven-membered cis- and trans-heterocyclic amino alcohols of which the trans-isomers were major products. The newly found radical cyclization provides a novel method for preparing not only bifunctionalized heterocyclic compounds but also adjacently functionalized amino alcohols carrying two quaternary carbons.

Journal Article↗
PubMedDate not supplied

Influence of cyclosporin on steroid-induced cataracts after renal transplantation.

PURPOSE: To study the effect of cyclosporin (CsA) on steroid-induced cataracts in patients following renal transplantation. METHODS: The subjects comprise 140 patients who had undergone renal transplantation at Kanazawa Medical Hospital. These subjects had received ophthalmologic examinations prior to their surgery and subsequently over the span of 12 months following surgery. The charts of these patients were re-examined for this study. The subjects were divided into two groups: the conventional therapy group (Group C) that received azathioprine and methylprednisolone; and the triple therapy group (Group T) that received azathioprine, methylprednisolone, and CsA. There were 73 and 67 patients in Groups C and T, respectively. The cataracts were classified according to Crews' classification. Steroid-induced cataract was diagnosed when vacuoles were observed or opacity was evident in the posterior subcapsular region. Subjects who exhibited any lens opacity before renal transplantation were excluded from this study. RESULTS: The total amounts of systemic steroid administered during the first year and at the final observation period were significantly lower in Group T than in Group C. The prevalence of steroid-induced cataracts of grade 1 and above was 55% and 63% for the first year, 73% and 89% for the second year, 74% and 92% for the third year, and 83% and 96% for the fifth year in Groups C and T, respectively. By the third year, the percentage of subjects exhibiting corrected visual acuity <0.8 or receiving cataract surgery was significantly higher in Group T than in Group C. There was no significant difference in the total dose of steroids, in subjects with cataracts over grade 1 and those with grades 0 and 1, between these groups. In Group C, the total steroid pulse therapy dose was significantly higher in subjects with steroid-induced cataracts over grade 1 than in those with grades 0 and 1. CONCLUSIONS: The observed rate of steroid-induced cataracts increased with the use of cyclosporin, despite a decrease in the total dose of systemic steroids. From this finding we suggest that the additional use of CSA may contribute to the development of steroid-induced cataracts. Steroid pulse therapy is considered a risk factor for the development of steroid-induced cataracts.

Adolescent↗