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Biomedical subjects

Akira Namera

Publications and source records attributed to Akira Namera.

33 records · Page 2Linked to original sources
PubMed2003

Routine analysis of amphetamine and methamphetamine in biological materials by gas chromatography-mass spectrometry and on-column derivatization.

A simple determination method of amphetamine (AP) and methamphetamine (MA) in biological materials was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). AP and MA in biological materials were adsorbed on the surface of Extrelut and then extracted and derivatized simultaneously on the Extrelut column. AP and MA were derivatized to the N-propoxycarbonyl derivatives using propylchloroformate. Pentadeuterated MA was used as an internal standard. The recoveries of AP and MA from urine were 88.2 and 92.5%, and those from blood were 89.7 and 90.3%, respectively. The calibration curves showed linearity in the range of 12.5-2000 ng/ml (ng/g) for AP and MA in urine and blood, and 0.25-20 ng/mg in hair. When urine samples containing two different concentrations (200 and 1000 ng/ml) of AP and MA, blood samples containing two different concentrations (200 and 1000 ng/g) of AP and MA, hair samples containing two different concentrations (0.5 and 5.0 ng/mg) of AP and MA, the coefficients of variation of intra-day and inter-day were 0.68-3.60% in urine, 0.42-4.58% in blood, and 1.20-13.1% in hair. Furthermore, this proposed method was applied to a medico-legal case of MA intoxication.

Adult↗
PubMed2003

[A rapid determination kit for acetaminophen].

Acetaminophen (APAP: N-Acetyl-p-amino-phenol) is widely used as a nonprescription analgesic and antipyretic drug. Although APAP is usually well tolerated when used at the recommended dose, overdose has been associated with lethal hepatic necrosis. This toxicity has been correlated with elevated serum or plasma APAP levels and/or a halftime of elimination from these fluids exceeding four hours. Therefore a rapid method for determination of APAP is needed to treat a patient with an acute APAP overdose. We developed a simple and rapid method for determination of APAP and prepared a test kit. The test kit was based on the colorimetric method (indophenol method), but not including stinking reagents. The reaction mixture assumed pale blue to dark blue according to APAP concentrations and the determination range was 10-200 micrograms/mL with the naked eye. It took only 15 minutes for this test. In addition, the test kit could be adapted to APAP test in urine. We believe that the new APAP determination kit will be a useful tool for emergency diagnosis.

Acetaminophen↗
PubMed2002

Quantitative analysis of tropane alkaloids in biological materials by gas chromatography-mass spectrometry.

A simple and rapid method for quantitation of tropane alkaloids in biological materials has been developed using an Extrelut column with gas chromatography-mass spectrometry (GC-MS). Biological materials (serum and urine) were mixed with a borate buffer and then applied to an Extrelut column. The adsorbed tropane alkaloids were eluted with dichloromethane before a GC-MS analysis. Atropine-d(3) was used as an internal standard. The extracted tropane alkaloids were converted to trimethylsilyl derivatives prior to GC analysis, to improve the instability of tropane alkaloids from heating and the property of them for a GC column. The recoveries of the compounds, which had been spiked to biological materials, were more than 80%. The GC separation of the derivatives from endogenous impurities was generally satisfactory with the use of a semi-polar capillary column. Tropane alkaloids showed excellent linearity in the range of 10-5000 ng/ml and the limit of detection was 5.0 ng/ml for biological materials. The present method is simple and more rapid than those previously reported, and was applied to a poisoning case. It is useful for the routine analysis of tropane alkaloids in cases of suspected tropane alkaloids poisoning.

Aged↗
PubMed2002

Direct extract derivatization for determination of amino acids in human urine by gas chromatography and mass spectrometry.

The purpose of this study was to develop a simple and accurate analytical method to determine amino acids in urine samples. The developed method involves the employment of an extract derivatization technique together with gas chromatography-mass spectrometry (GC-MS). Urine samples (300 microl) and an internal standard (10 microl) were placed in a screw tube. Ethylchloroformate (50 microl), methanol-pyridine (500 microl, 4:1, v/v) and chloroform (1 ml) were added to the tube. The organic layer (1 microl) was injected to a GC-MS system. In this proposed method, the amino acids in urine were derivatized during an extraction, and the analytes were then injected to GC-MS without an evaporation of the organic solvent extracted. Sample preparation was only required for ca. 5 min. The 15 amino acids (alanine, aspartic acid, cysteine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine, tryptophan, valine) quantitatively determined in this proposed method. However, threonine, serine, asparagine, glutamine, arginine were not derivatized using any tested derivatizing reagent. The calibration curves showed linearity in the range of 1.0-300 microg/ml for each amino acid in urine. The correlation coefficients of the calibration curves of the tested amino acids were from 0.966 to 0.998. The limit of detection in urine was 0.5 microg/ml except for aspartic acid. This proposed method demonstrated substantial accuracy for detection of normal levels. This proposed method was limited for the determination of 15 amino acids in urine. However, the sample preparation was simple and rapid, and this method is suitable for a routine analysis of amino acids in urine.

Amino Acids↗
PubMed2002

Analysis of anatoxin-a in aqueous samples by solid-phase microextraction coupled to high-performance liquid chromatography with fluorescence detection and on-fiber derivatization.

A simple method for analysis of anatoxin-a in aqueous samples was developed using solid-phase microextraction (SPME) and high-performance liquid chromatography (HPLC) with fluorescence detection. Anatoxin-a was derivatized to a fluorogenic agent on the surface of the SPME fiber. In the method an SPME fiber was immersed for 30 min in the aqueous sample. The fluorogenic derivatizing reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, 1.0 mg/ml in methanol) was dropped or sprayed onto the fiber containing extracted analytes. The fiber was then heated for 10 min in an empty vial at 70 degrees C in a waterbath to promote derivatization. The derivatives formed on the fiber were desorbed in a SPME-HPLC interface. The interface was filled with methanol-1 mM hydrochloric acid (7:3, v/v) before inserting of the fiber into the interface. For desorption, the fiber was inserted in the interface for 5 min. For anatoxin-a in an aqueous sample, the calibration curve showed linearity in the range of 50-1500 ng/ml and the limit of detection of anatoxin-a was 20 ng/ml. No interferences were found, and the time for analysis was 55 min for one sample.

Bacterial Toxins↗
PubMed2002

On-column derivatization for determination of amphetamine and methamphetamine in human blood by gas chromatography-mass spectrometry.

A simple determination method of amphetamine (AP) and methamphetamine (MA) in human blood was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). AP and MA were adsorbed on the surface of Extrelut and then derivatized the N-propoxycarbonyl derivatives using propylchloroformate. Pentadeuterated MA was used as an internal standards. The recoveries of AP and MA from the spiked blood were 89.7 and 90.3%, respectively. The calibration curves showed linearity in the range of 12.5-2000 ng/g for AP and MA in blood. The coefficients of variation of intraday and interday were 0.42-4.58%. Furthermore, this proposed method was applied to some medico-legal cases of MA intoxication. MA and its metabolite AP were detected in the blood samples, and the correlation of the blood level of amphetamines and the behaviors of the victims was in good agreement with the criteria proposed by Nagata [Jpn. J. Legal Med. 37 (1983) 513].

Adult↗
PubMed2002

Automated headspace solid-phase microextraction and in-matrix derivatization for the determination of amphetamine-related drugs in human urine by gas chromatography-mass spectrometry.

An automated extraction and determination method for the gas chromatography (GC)-mass spectrometry (MS) analysis of amphetamine-related drugs in human urine is developed using headspace solid-phase microextraction (SPME) and in-matrix derivatization. A urine sample (0.5 mL, potassium carbonate (5 M, 1.0 mL), sodium chloride (0.5 g), and ethylchloroformate (20 microL) are put in a sample vial. Amphetamine-related drugs are converted to ethylformate derivatives (carbamates) in the vial because amphetamine-related drugs in urine are quickly reacted with ethylchloroformate. An SPME fiber is then exposed at 80 degrees C for 15 min in the headspace of the vial. The extracted derivatives to the fiber are desorbed by exposing the fiber in the injection port of a GC-MS. The calibration curves show linearity in the range of 1.0 to 1000 ng/mL for methamphetamine, fenfluramine, and methylenedioxymethamphetamine; 2.0 to 1000 ng/mL for amphetamine and phentermine; 5.0 to 1000 ng/mL for methylenedioxyamphetamine; 10 to 1000 ng/mL for phenethylamine; and 50 to 1000 ng/mL for 4-bromo-2,5-dimethoxyphenethylamine in urine. No interferences are found, and the time for analysis is 30 min for one sample. Furthermore, this proposed method is applied to some clinical and medico-legal cases by taking methamphetamine. Methamphetamine and its metabolite amphetamine are detected in the urine samples collected from the patients involved in the clinical cases. Methamphetamine, amphetamine, and phenethylamine are detected in the urine sample collected from the victim of a medico-legal case.

Amphetamine-Related Disorders↗
PubMed2002

Acute liver failure following intravenous methamphetamine.

A 41-y-o Pakistani man presented with psychosis, hyperthermia, rhabdomyolysis, and liver dysfunction approximately 6 h after i.v. injection of methamphetamine. Serum concentrations of methamphetamine and amphetamine on admission were 0.30 microg/mL and 0.04 microg/mL, respectively. Total serum bilirubin and alanine aminotransferase concentrations peaked on the 3rd hospital day at 8.6 mg/dL and 4155 IU/L, respectively, and gradually returned to normal with supportive care. The patient had no evidence of infectious hepatitis or intake of other drugs. Histologic examination of a liver biopsy specimen obtained on the 11th d showed confluent necrosis and ballooning degeneration in centrilobular zones. No inflammatory changes were seen in portal tracts. Liver damage can be a complication of illicit methamphetamine use, even in patients without viral infection or intake of other drugs.

Adult↗