Search

Genipin was reacted with benzylamine and several amino acids to prepare gardenia blue (GB). The time-course of GB formation with benzylamine was monitored by high-performance liquid chromatography (HPLC), liquid chromatography time-of-flight mass spectrometry (LC-TOFMS), and

Objectives: Recently, the dart-throwing motion (DTM) has attracted attention as a functional direction of wrist joint motion. Consequently, we devised a new artificial muscle-type dynamic orthosis (Dynamic Traction Splint by Artificial Muscle, DTSaM) to reproduce DTM. This study analyzed the automatic motion of the wrist joint using a three-dimensional motion analysis system to assess how closely the DTSaM replicates DTM. Methods: The DTSaM orthosis incorporates two McKibben-type rubber artificial muscles, and measurements were performed using image analysis software and a three-dimensional motion analysis system. The wrist radial angle (WRA) was defined as the angle between the line connecting the head of the index finger metacarpal to the radial styloid process and the line connecting the radial styloid process to the lateral epicondyle of the humerus. WRAs were investigated from 60° of palmar flexion to 60° of dorsiflexion. Results: For dorsiflexion, comparisons of radial deviation and wrist ulnar angle (WUA) between the motion obtained using the DTSaM orthosis and active DTM showed a significant difference (P

Electromyography (EMG) and mechanomyography (MMG) have been used to directly evaluate muscle function through the electromechanical aspect of muscle contraction. The purpose of this study was to establish new absolute indices to describe muscle contraction performance during dynamic exercise by combining EMG and displacement MMG (dMMG) measured simultaneously using our previously developed MMG/EMG hybrid transducer system. Study participants were eight healthy male non-athletes (controls) and eight male athletes. EMG and dMMG of the vastus medialis were measured for 30 s during four cycles of recumbent bicycle pedaling (30, 60, 90, and 120 W) and on passive joint movement. Total powers were calculated based on the time domain waveforms of both signals. Muscle contraction performance was verified with the slope of regression line (SRL) and the residual sum of squares (RSS) obtained from EMG and dMMG correlation. EMG and dMMG has increased with the work rate. Force and EMG were similar between groups, but dMMG showed a significant difference with load increase. Athletes had significantly higher SRL and significantly lower RSS than controls. The average value divided by SRL and RSS was higher in athletes than in controls. The indices presented by the combined approach of EMG and dMMG showed a clear contrast between the investigated groups and may be parameters that reflect muscle contraction performance during dynamic exercise.

Aim: Non-alcoholic steatohepatitis (NASH) increases cardiovascular risk regardless of risk factors in metabolic syndrome. However, the intermediary factors between NASH and vascular disease are still unknown because a suitable animal model has never been established. The stroke-prone (SP) spontaneously hypertensive rat, SHRSP5/Dmcr, simultaneously develops hypertension, acute arterial lipid deposits in mesenteric arteries, and NASH when feed with a high-fat and high-cholesterol (HFC) diet. We investigated whether SHRSP5/Dmcr affected with NASH aggravates the cardiac or vascular dysfunction. Method: Wister Kyoto and SHRSP5/Dmcr rats were divided into 4 groups of 5 rats each, and fed with a SP or HFC diet. After 8 weeks of HFC or SP diet feeding, glucose and insulin resistance, echocardiography, blood biochemistry, histopathological staining, and endothelial function in aorta were evaluated. Results: We demonstrate that SHRSP5/Dmcr rats fed with a HFC diet presented with cardiac and vascular dysfunction caused by cardiac fibrosis, endothelial dysfunction, and left ventricular diastolic dysfunction, in association with NASH and hypertension. These cardiac and vascular dysfunctions were aggravated and not associated with the presence of hypertension, glucose metabolism disorder, and/or obesity. Conclusions: SHRSP5/Dmcr rats may be a suitable animal model for elucidating the organ interaction between NASH and cardiac or vascular dysfunction.

The summation of the muscle force caused by an increase in the firing rate is named a tetanic contraction (tetanus), and the minimum stimulation frequency necessary to evoke an unfused/fused tetanus is related to the contraction time (CT) and relaxation time (RT) of the twitch. In particular, the fusion index (FI) is a very useful indicator, and it is used to evaluate the change in the muscle fiber component ratio. However, the measurement of the FI is invasive, because most patients experience pain during the electrical stimulation for tetanus. We expect that the twitch parameters CT and RT can substitute for the FI in the future. We found that the minimum stimulation frequency necessary to evoke the unfused/fused tetanus can be estimated from the twitch parameters as a first step. The results showed that (1) the minimum stimulation frequencies calculated from twitch parameters during unfused/fused tetanus were very similar to those calculated from FI parameters, and (2) they were also strongly correlated with FI parameters regardless of fiber components. The basic characteristics of tetanic progression in different fiber types could be estimated from twitch parameters.

Collateral ligament shortening causes extension contractures of the metacarpophalangeal joint, and dynamic flexion splinting has been widely used to treat these contractures; however, there are various problems with these approaches. We developed a novel, pneumatic-type dynamic traction and flexion splint to solve these problems.A total of 25 fingers were treated with the dynamic traction and flexion splint for 8 weeks. Every 2 weeks, the average metacarpophalangeal joint flexion angle, total active motion, grasp strength, and pain scores were assessed.The finger flexion angle was significantly greater at the final evaluation, starting after 6 weeks of treatment (p 0.05), than prior to treatment. Similarly, the total active motion results improved significantly over 8 weeks.Our results show that use of the dynamic traction and flexion splint improves patient finger functioning and flexural angle.The dynamic traction and flexion (DTF) splint appears to be effective for treating patients.

The limited loadability of mineral oil filled transformers leads the users to select the transformer size necessary to meet the required peak demand; this causes the nominal rating to be higher than necessary for the typical demand resulting in transformers that have low annual average loading. The association of a transformer using high temperature insulation system, having both the solid (thermally upgraded Kraft paper) and liquid insulation (natural ester dielectric liquid) thermal classes higher than conventional, with the strategy of defining the nominal rating based on the conventional temperature rise limits lead to transformers holding a “reserve capacity”. This significant additional capacity without accelerated life consumption of the paper and no oil degradation enhances the loadability of the transformers and can be used to handle yearly peak demand by means of a smaller transformer. Brazilian utility CELESC adopted this concept for twelve natural ester filled transformers, which were installed and monitored in service for a period of one year. The reduction of the no-load losses of the smaller transformer resulted in 22.7% reduction of total dissipated energy in the period. Detailed results are presented in this study. Besides the advantage of improving system efficiency, the reduction of the nominal rating of the transformers also brings savings in transformer purchasing, and reduces environmental impact, mitigates the risk of fire, which are important issues for the utility.

In this paper, we introduce a new estimation method for total creatine phosphokinase release based on a physiological model of the serum creatine phosphokinase (CPK) activity change that can be used to estimate the total CPK release accurately, as early as possible, without frequent blood sampling. The physiological model and a new calculation method were applied to the serum CPK activity change of patients who suffered acute myocardial infarction (AMI). According to the results, the physiological model showed good agreement with the serum CPK activity change and the estimated value of the total CPK release also agreed well with that calculated using the conventional technique with clinically acceptable accuracy.

Background To the best of our knowledge, there have been no reports on the pharmacokinetics and pharmacodynamics during the conversion from continuous intravenous infusion (CII) to transdermal fentanyl administration. The primary objective of the present study was to clarify the pharmacokinetic characteristics during this conversion. A secondary objective was to identify an association between serum albumin and the absorption of fentanyl from the transdermal patch. Methods A prospective study was conducted from February 2010 to August 2011 that enrolled 19 patients with chronic cancer pain. Patients were classified into 2 study groups according to body mass index and albumin level. All patients received the conversion from CII to transdermal fentanyl using a 2-step taper of CII over 6 hours. Comparisons of efficacy, toxicity, and serum fentanyl concentrations between study groups were analyzed at baseline, 3, 6, 9, 12, 15, 18, and 24 hours after initiation of the conversion. Results The dose-adjusted serum fentanyl concentrations for all patients were significantly decreased at 15 to 24 hours after conversion compared with baseline, although pain intensity and the number of rescue events remained stable during the conversion. The dose-adjusted serum fentanyl concentrations at 9 to 24 hours were significantly reduced in the low albumin group compared with the normal albumin group (P Conclusions Our study demonstrated that the dose-adjusted serum fentanyl concentrations remained relatively stable, and pain intensity and the number of rescue events remained stable during conversion. Hypoalbuminemia was strongly associated with poor absorption of transdermally administered fentanyl.

Spacer cable system has been widely used in Brazil in low polluted areas such as rural and urban areas. However, Brazilian national standards do not recommend installing spacer cable systems in medium and high polluted areas due to the accelerated aging of the electrical equipment and accessories. In this paper is presented the evaluation of alternatives for the use of spacer cable system in these areas by using new materials on the interface between the covered conductor and the spacer. Other components evaluated were porcelain and polymeric insulators. Besides the standard configuration, different materials were applied on the interface between the cable and the spacer: semiconducting tubes on the cable, autofusion semiconducting tape on the cable and semiconducting tape on the spacer. These materials were submitted to multiple stress tests and its performance were evaluated by visual inspections and leakage current measurements.

Background Respiratory muscle strength has been used as a tool for evaluating respiratory rehabilitation in chronic obstructive pulmonary disease. However, mouth pressure measurement evaluated by maximum expiratory mouth pressure (PEmax) or inspiratory mouth pressure (PImax) offers an indirect method for measuring respiratory muscle strength. We demonstrated the evaluation of diaphragm contractility using a mechanomyogram (MMG), which is the mechanical signal generated by the motion of the diaphragm induced by the electric stimulation of the phrenic nerve. Methods Study participants were 21 young and 20 elderly subjects with no symptoms of respiratory disease. The elderly subjects were divided into non-smoker or smoker groups. The smoker group was defined as subjects having a Brinkman Index of greater than 300. We measured basic spirometric parameters, mouth pressure (PEmax, PImax), and diaphragmatic MMG. Results Diaphragmatic MMG showed more clear contrast between young subjects and elderly non-smoker or smoker subjects than the conventional method for respiratory muscle contraction (PEmax, PImax). In addition, the diaphragmatic MMG strongly correlated with inspiratory muscle strength. Conclusions Diaphragmatic MMG may reflect diaphragmatic contractility more directly and sensitively than the conventional method.

We have proposed a novel and first strategy of high-speed countercurrent chromatography (HSCCC) purification for the efficient and effective discovery of antioxidant from natural product based on on-line HPLC method with radical scavenging assay. To achieve a strategy for HSCCC purification, the antioxidants in materials are identified by on-line HPLC with DPPH radical scavenging assay. Then, the optimal condition of target peaks would be investigated for the two-phase solvent system, and purified by HSCCC. In this study, the specific antioxidants in red cabbage, perilla and elderberry pigments were evaluated by on-line HPLC with DPPH radical scavenging assay, and purified by HSCCC technique. Specific antioxidants could be rapidly pinpointed in complex mixtures by on-line HPLC with DPPH radical scavenging assay. Then, the optimal two-phase solvent systems were investigated using these HPLC peaks. Finally, the purification of these nine antioxidants form three mixtures were performed by HSCCC. Using mass spectrometric analysis, these antioxidants were confirmed to cyanidin-based anthocyanin from red cabbage and elderberry pigments, and luteolin-based flavones from perrilla pigment. Due to the advantages derived from on-line HPLC with DPPH radical scavenging assay and HSCCC technique, a rapid, efficient and effective strategy has been developed for the discovery of antioxidants from natural products.

We present a selective method for simultaneous determination of five polyether ionophores such as salinomycin (SAL), monensin (MON), narasin (NAR), semduramicin (SEM) and lasalocid (LAS) in aquatic samples using a liquid chromatography with one-step fluorescent derivatization of 2-(4-hydrazinocarbonyl-phenyl) 4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H-imidazol-2-yl) benzoyl chloride hydrochloride (DIB-Cl). Fluorescent one-step derivatization for SAL, MON, NAR and SEM using HCPI and for LAS using DIB-Cl was monitored by an LC/fluorescence detector (E(x), 340 nm; E(m), 465 nm). Chromatographic separation was performed on a TSK-GEL ODS-120T (4.6 × 150 mm, 3 µm) column using a mobile phase of 0.1% formic acid in acetonitrile and 0.5 mM ammonium formate in water (70/30, v/v). The limits of detections were 0.01 µg/mL (50 pg) for LAS, 0.05 µg/mL (250 pg) for SAL, NAR and SEM, and 0.1 µg/mL (500 pg) for MON, respectively. The recoveries for water samples were indicated to be the range of 79.6 ± 6.4 - 99.0 ± 4.4% with associated precision values (between-day for 3 days) for repeatability. Based on solid-phase extraction, the limit of quantitation values indicated 0.1 ng/mL for SAL, MON, NAR and SEM, and 0.01 ng/mL for LAS in water samples.

We present a sensitive and selective method for detecting imidocarb in bovine tissues and milk samples using a solid-phase extraction (SPE) with diatomaceous earth column and liquid chromatography with electrospray tandem mass spectrometry (LC-ESI-MS/MS) on positive mode. Chromatographic separation was performed on a TSK-GEL ODS 100 V column using 0.1% formic acid in water/methanol. Limit of detection (LOD) was 0.5 ng/mL for standard solution. Limit of quantitation (LOQ) was ranged from 1.0 to 10 µg/kg for bovine tissue and milk samples. The linearity of the calibration curve was excellent in matrix matched standards, and yielded the coefficients (r2 = 0.997–0.999, range from LOQ to 250, 750, or 5000 µg/kg) of imidocarb. Recoveries were in the range of 73.3–98.6% with associated precision values (within-day: 1.0–6.7%, n = 6, and between-day: 2.0–7.7% for 3 days) for repeatability and reproducibility. This developed method is well adapted for residue analysis of imidocarb in bovine tissues and milk based o...

Inhibition of angiotensin-converting enzyme (ACE) by various foods decreases the blood pressure. ACE inhibitors derived from natural components may be of therapeutic value in preventive medicine. In this study, we report a novel screening assay of ACE inhibitors from complex natural colourants and foods that employ solid phase extraction (SPE), high-throughput liquid chromatography (LC) separation, and stable isotope dilution electrospray tandem mass spectrometry (SID-ESI-MS/MS). When a target sample was subjected to N-Hippuryl-His-Leu (HHL) and ACE in phosphate buffer (pH 7.4), generated hippuric acid (HA) was extracted by SPE. LC/SID-ESI-MS/MS detection of HA allowed us to accurately identify the effects of complex substances such natural colourants and foods that inhibit the ACE of HHL. The major HA and HA-d5 fragment ions at m/z 180→105 and 185→110 in the multiple reaction monitoring (MRM) mode can quantify levels that are lower than other methods. The LC/SID-ESI-MS/MS method described here is a rapid, selective, sensitive, and highly reproducible method for the determination of HA in various samples. Based on the assay developed, all samples such as natural colourants, infant formula, soy paste, ketchup, mayonnaise, wheat flour, orange juice, supplement drink, tea, and coffee could be accurately measured for ACE inhibition in various matrices. High-throughput LC/SID-ESI-MS/MS assay has no limitations in the evaluation of inhibition activity in various natural samples such as colour, high-matrix, and processed foods.

We developed a useful and preparative method based on high-speed counter-current chromatography with mass spectrometry (HSCCC/MS) to purify gentamicin C1a, C2/2a and C1 from standard powder. The analytes were purified on the HSCCC model CCC-1000 (multi-layer coil planet centrifuge) with a volatile two-phase solvent system composed of n-butanol/10% aqueous ammonia solution (50:50, v/v) and detected on an LCMS-2020EV quadrupole mass spectrometer fitted with an electrospray ionization (ESI) source system in positive ionization following scan mode (m/z 100-500). The HSCCC/ESI-MS peaks indicated that gentamicin C1a (m/z 450: [M+H](+)), C2/2a (m/z 464: [M+H](+)) and C1 (m/z 478: [M+H](+)) have the peak resolution values of 1.3 and 1.7 from 30 mg of loaded gentamicin powder. The HSCCC yielded 3.9 mg of gentamicin C1a, 12.6 mg of gentamicin C2/2a and 12.0 mg of gentamicin C1. These purified substances were analyzed by LC/MS with scan positive-mode. Based on the LC/MS chromatograms and spectra of the fractions, analytes were estimated to be over 95% pure. These gentamicin isomers of C1a, C2/2a and C1 were evaluated for their antibacterial activities. The overall results indicate that this approach of HSCCC/MS is a powerful technique for the purification of gentamicin components.

We developed a sensitive, selective and accurate method based on liquid chromatography with tandem mass spectrometry (LC–MS/MS) to determine N-terminal thymosin-β peptides of Ac-SDKP and Ac-ADKP in human plasma samples. Quantification of Ac-SDKP and Ac-ADKP was performed using solid phase extraction (SPE) based on C 18 , reversed phase LC separation, and stable isotope dilution electrospray ionization-MS/MS in multiple reaction-monitoring (MRM) mode. The Ac-SDKP- 13 C 6 , 15 N 2 and Ac-ADKP-d 7 were synthesized for the internal standards. These MRM monitoring ions were m / z 488 → 129 (quantitative ion)/226 for Ac-SDKP, m / z 496 → 137 for Ac-SDKP- 13 C 6 , 15 N 2 , m / z 472 → 129 (quantitative ion)/226 for Ac-ADKP, and m / z 479 → 129 for Ac-ADKP-d 7 , respectively. Lower limit of quantitation (LLOQ) of Ac-SDKP and Ac-ADKP was 0.1 ng/mL in human plasma. Recovery values were ranged from 94.7% to 106.3% for inter- (RSD: 0.6–3.5%) and intra- (RSD: 0.4–4.9%) day assays. Plasma Ac-SDKP levels were significantly higher in hemodialyzed subjects treated with angiotensin-converting enzyme inhibitors of enalapril (27.3 ± 24.6 ng/mL, n = 10) and trandolapril (12.3 ± 16.9 ng/mL, n = 18) than healthy (0.4 ± 0.2 ng/mL, n = 7) and hemodialyzed subjects (0.6 ± 0.2 ng/mL, n = 34). This analytical method would be useful to measure N-terminal thymosin-β peptides in human plasma for the clinical study.

A method for the quantitation of nucleotides (adenosine 5'-monophosphate (AMP), guanosine 5'-monophosphate (GMP), uridine 5'-monophosphate (UMP), cytidine 5'-monophosphate (CMP), and inosine 5'-monophosphate (IMP)) in infant formula was developed by hydrophilic interaction chromatography with tandem mass spectrometry (HILIC-MS/MS). The internal standards used (AMP-13C10, 15N5; GMP-13C10, 15N5; UMP-13C9, 15N2; CMP-13C9, 15N3) were prepared with centrifugal ultrafiltration (CUF). Data acquisition was achieved by using multiple reaction monitoring (MRM) of product ions of protonated molecules of the five nucleotides generated by the positive-ion ESI. HILIC conditions were performed with 30 mmol/L ammonium formate in water (pH 2.5, adjusted with formic acid) and methanol. The LOD and LOQ were 5-10 μg/mL and 10-30 μg/mL for standard solution, respectively. Recovery for intra- and interday assays ranged from 98.1 to 108.9% (RSD: 0.7-5.4%) spiked with three concentration levels (5, 25, and 250 μg/g powder infant formula). This method could be applied for the determination of nucleotides in infant formula samples. The detected concentrations of five nucleotides ranged from not detected (n.d.) to 278 μg/g powder infant formula. The total nucleotide level ranged from n.d. to 600.2 μg/g powder infant formula.

In the present study, a novel assay for screening inhibitors of Cu(II) ion/adrenaline-mediated oxidative modification of N-terminal amyloid beta (Abeta) peptides was developed using liquid chromatography with mass spectrometry (LC/MS). The physiological condition of Cu(II) ion/adrenaline in buffer (pH 7.4) at 37 degrees C for 90 min revealed a specific modification of N-terminal Abeta peptides, such as Abeta1-6, Abeta1-40, and Abeta1-42, using trypsin digestion and LC/MS detection of the modified Abeta peptide. When this oxidative modification of the shorter N-terminal Abeta1-6 was subjected to LC/MS, single charged ions from native peptide ([M+H]+, m/z 774) were observed at m/z 729 and 685, corresponding to a decrease in mass of 45 and 89 Da, respectively, as compared with the original peptide. To determine the effect of specific antioxidants, a screening assay to find inhibitors of Cu(II) ion/adrenaline-mediated oxidation was developed based on the response ratio of m/z 685 to 774. LC/MS detection of the modified peptides allowed us to identify antioxidants that inhibit oxidative modification of Abeta1-6 model peptide. The oxidative modification of Abeta1-6 was inhibited by curcumin but not an isoflavone or catechin mixture or saponin or capsaicin, revealing a clear difference between antioxidants that inhibit oxidative modification and other antioxidants. This novel assay may allow for the identification of antioxidants that protect against oxidative modification of Abeta and other proteins related to oxidative stress by adrenaline and Cu(II) ions under normal physiologic conditions.

An LC/ESI (positive-mode)-MS/MS method was developed for simultaneous quantification of 8 macrocyclic lactones (abamectin B1a, abamectin 8,9-Z isomer B1a, emamectin benzoate B1a, emamectin benzoate 8,9-Z isomer B1a, ivermectin, eprinomectin B1a, doramectin and moxidectin) in animal tissues, egg, milk and honey. The separation was achieved on a TSK-GEL ODS 100 V column (2.0 x 50 mm, 3 microm) with a mobile phase consisting of 0.1% formic acid in acetonitrile, and 0.1 mM ammonium formate-0.1% formic acid in water, at a flow rate of 0.2 mL/min with gradient elution. Linear calibration plots were obtained with high correlation coefficients (r=0.998-0.999). The LOQ and LOD ranged from 0.02-1.5 ng/mL and 0.1-5 ng/mL, respectively. Average recoveries were in the range of 70.8-117.1% with associated RSD values

Analytical method for the simultaneous quantification of avermectins (AVMs), abamectin B1a, abamectin 8,9-Z isomer B1a, emamectine benzoate B1a, emamectine benzoate 8,9-Z isomer B1a, ivermectin, eprinomectin B1a, doramectin and moxidectin in bovine tissues (muscle, liver and fat) was developed by LC-MS/MS in electrospray positive ion mode. The separation was achieved on a short TSK-GEL ODS 100V column with the mobile phase consisting of acetonitrile and aquatic 0.1 mM ammonium formate containing 0.1% formic acid v/v at a flow rate of 0.2 mL/min with gradient elution. Liquid-liquid extraction with isooctane was used for the sample extraction/preparation of analytes in bovine samples. The linearity of the calibration curves was excellent in matrix-matched standards, and yielded the coefficients (r(2)=0.997-0.999, range from LOQ to 500, 1000 or 5000 ng/g) of determination of the target analytes. Recoveries were in the range of 87.9-99.8% with associated precision values (within-day: 1.5-7.4%, n=6, and between-day: 1.5-8.4% for 3 days) for repeatability and reproducibility. LC-MS/MS method has been proven to be highly efficient and suitable for the simultaneous determinations of eight AVMs in bovine tissue samples.

A fast and simple method for the quantitative determination of bicozamycin (BCM) in milk samples by hydrophilic interaction liquid chromatography with electrospray tandem mass spectrometry (HILIC-ESI-MS/MS) and centrifugal ultrafiltration (CUF) was presented. The milk sample was extracted with an acetonitrile/water (4/1, v/v) and CUF procedure. After preparation, the sample solution was directly injected onto the HILIC-MS/MS. Chromatographic separation of the components was performed on a TSK-GEL NH2 column using 50 mM ammonium acetate in water (pH 4.0 adjusted with acetic acid) and acetonitrile. The mass spectrometer was operated in the negative ESI-MS/MS mode (m/z 301 → 209). The LOD and LOQ were 2.5 ng/mL (25 pg) and 5 ng/mL, respectively. This method was validated according to the Japanese maximum residue limit (0.1 µg/g) of BCM. The matrix matched calibration of BCM was linear over the calibration range from 50 to 500 ng/g (r2 = 0.999). Recovery values were from 82.6 to 109.9% (RSD 7.5%, n =...

We present a rapid and simple method for detecting novobiocin in biologic samples using a methanol-based extraction of the tissue matrix and liquid chromatography with electrospray tandem mass spectrometry (LC-ESI-MS/MS) on positive mode. The sample, prepared using centrifugal ultrafiltration with 5.0% SDS, was directly injected into the LC-MS/MS. Chromatographic separation was performed on a TSK-GEL ODS 100 V column using 0.5% formic acid in water/methanol. The method was validated according to the Japanese Maximum Residue Limits recommendations. Detection was linear over a range of 5–100 ppb matrix solution (r > 0.998). Novobiocin recovery values from chicken (0.05 ppm) and fish tissues (0.05 ppm), milk (0.08 ppm), and human serum (0.05 and 0.01 ppm) samples ranged from 71 ± 1 to 95 ± 2%.

Production of microregional catalytic reactive oxygen species (ROS) by metal-binding amyloid-beta (Abeta) peptides mediates the neurotoxicity of Alzheimer's disease, and inhibitors of this activity may be of therapeutic value. No current analytical methods target specific ROS inhibitors produced by metal-binding peptides. We report a screening assay for metal-catalyzed oxidation (MCO) inhibitors based on liquid chromatography-mass spectrometry (LC-MS) with a model N-terminal Abeta peptide (Abeta(1-6)). When subjected to MCO by Cu(II)/ascorbic acid, singly and doubly charged Abeta(1-6) molecules were observed at m/z 729.2 and 364.8 and m/z 685.3 and 343.3, respectively, corresponding to a decrease in mass of 45 and 89 Da compared with the model peptide. In contrast, H(2)O(2) did not modify the Abeta(1-6) peptide. Modified peptides were characterized by a specific MCO of Abeta(1-6), which contains both His and N-terminal Asp residues. LC-MS detection of the modified peptides allowed us to identify antioxidants that inhibit MCO of Abeta(1-6). MCO of the model peptide was inhibited by curcumin, but not dibutylhydroxytoluene, carotene, tocopherol, estradiol or nicotine, revealing a clear difference between curcumin and other antioxidants. This novel assay may allow for the identification of antioxidants that protect against MCO of peptides and proteins related to degenerative diseases.

Dual counter-current chromatography (dual CCC)-tandem mass spectrometry (MS/MS) was successfully performed with a newly designed spiral column for dual CCC. The small column capacity required for directly coupling with electrospray MS/MS was accomplished by forming a rectangular spiral groove on a plastic disk and sealing it with a PTFE sheet. This novel dual CCC-MS/MS technique was successfully applied for the rapid determination of methomyl, fenobucarb and carbaryl pesticides in food. A two-phase solvent system of n-hexane-acetonitrile-0.1% formic acid (45:45:10) was suitable for both good dual CCC separation and sufficient ionization of pesticides. Recoveries of these three pesticides from mandarin orange and spinach samples fortified at 0.05 mg/kg were in the range of 93-107% with relative standard deviations of 2.4-3.8%.